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Kennedy/Jenks Consultants
© Kennedy/Jenks Consultants, Inc. SVCW Gravity Pipeline | Page 1
3 April 2017
Planning Level Technical Memorandum No. 4
To: Bruce Burnworth
From: Mark Minkowski, P.E., Kennedy/Jenks Team
Subject: Planning Level Technical Memorandum No. 4 – Shaft Construction
SVCW Gravity Pipeline
K/J Project Number: 1568063.02
Section 1: Introduction For the Introduction and background, refer to Section 1 of Planning Level TM No. 1.
1.1 Objectives The purpose of Planning Level TM No. 4 is to evaluate the shaft support methods for each of the 4
shaft locations, and to make a recommendation on a preferred method for each location. A
secondary objective of Planning Level TM No. 4 is to investigate and establish site conditions at the
staging areas and access requirements. This work includes reviewing the area needed at each
location for construction and for long term maintenance facility needs for accessing each shaft, with
conceptual site layouts showing temporary facilities.
1.2 Gravity Pipeline Description As shown in Figure 1-1, the Proposed Gravity Pipeline, shown in green in the figure, connects to
the recently constructed 48-inch force main project on Inner Bair Island and extends downstream
to connect at the proposed Receiving Lift Station (RLS) at the SVCW wastewater treatment plant
(WWTP). The currently proposed Gravity Pipeline consists of approximately 17,600 feet of 11-foot
diameter wastewater gravity pipeline inside a 13-foot inside diameter tunnel with four shafts. The
tunnel is to be constructed with its invert depth ranging between 35 and 65 feet in primarily firm to
stiff clay soils.
Ideas under consideration by SVCW may change the basic Gravity Pipeline description. SVCW
anticipates additional ideas coming out of the Progressive DB process. The ideas discussed to date
(including concepts suggested by PDBs already in contact with SVCW) include the following.
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Multiple-layers of defense against corrosion, including upstream dosing, enhanced air
circulation, laminar flow, bacteria disruption and high performance precast concrete tunnel
segments with sacrificial thickness. This concept would eliminate the pipe in the tunnel and
the related grout backfill of the annular space.
o Removal of the pipe in the tunnel, would allow SVCW to use the full inside diameter
of the tunnel for equalization of dry and wet weather flows. This approach would
result in deferral of a concrete storage surface structure at the WWTP.
Using Bair Island as the TBM launch location, resulting in elimination of the Airport Access
Shaft. Recent input from contractors interested in proposing in response to SVCW’s
Progressive Design Build planned RFQ/RFP indicates interest in launching the TBM at Bair
Island instead of the Airport Access Shaft. This would involve elimination of the Airport
Access Shaft, partial realignment of the tunnel near the eliminated shaft and a larger
construction footprint on Bair Island. If a selected PDB desires to pursue this alternative,
the alternative would need to be described and reviewed under CEQA and permitted. Both
appear to be challenging given the potential for public impacts and potential impacts on
endangered species.
Reconfiguration of the Receiving Lift Station that would modify the shape, size and
configuration of the shafts at the WWTP.
These ideas are not addressed directly in TM No. 3, but are provided here for reference during the
Progressive DB process.
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Planning Level Technical Memorandum No. 4
Shaft Construction
Figure 1-1: SVCW Proposed Project (Alternative 4BE)
1.3 Basic Approach The alignment and general shaft locations for the Gravity Pipeline were defined during the
conceptual development phase of design. The alignment and shaft location decisions were made
following a detailed alternatives evaluation process that concluded in July 2015 with a decision by
SVCW to study Proposed Project Alternative 4BE further as part of the CEQA EIR review process.
The alternatives evaluation process included consideration of up to 14 alternative alignments, with
varying trenchless construction methods, shaft options, and horizontal alignments between
upstream and downstream connection locations. Ultimately, the Proposed Gravity Pipeline was
identified for further study based on several success factors, including capital and life cycle cost,
minimal disruption to the public, and lower operations and maintenance impacts.
Section 2 provides a summary of the geologic conditions at each of the shafts. Section 3 discusses
design criteria. Section 4 is the discussion and analysis of alternative shaft construction approaches
for each of the shafts. Finally, Section 5 provides a summary and recommendations for further work
by the PDB.
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Planning Level Technical Memorandum No. 4
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Section 2: Geologic Conditions
2.1 Geologic Strata The information about general subsurface conditions along the proposed Gravity Pipeline
alignment is based on the Phase I subsurface exploration program performed by Geotechnical
Consultants Inc. (GTC), and its findings are presented in the "Preliminary Characterization of
Subsurface Conditions" Technical Memorandum dated December 9, 2015. The data from the Phase
II geotechnical investigation program was also utilized to confirm the information used from the
Phase I investigation program. The subsurface conditions consist of four soil layers: Artificial Fill,
Young Bay Mud, Upper Layered Sediments and Old Bay Deposits. Bedrock was not encountered
within the proposed depths of excavation for tunnel or shafts.
Artificial Fill covers the proposed alignment to depths of 2 to 15 feet below the ground surface. The
fill predominantly consists of silt and clay soil materials containing varying amounts of granular
materials (sand and gravel) and poorly graded sand and gravel. Cobbles and varying amounts of
organic materials are contained within the fill layer.
Young Bay Mud underlies the upper fill layer and extends from the bottom of the fill layer to depths
varying between 15 and 50 feet below the ground surface, with a layer thickness varying between 5
and 45 feet. The Young Bay Mud is predominantly light to dark gray, wet, very soft to soft Elastic Silt
or Fat Clay. Locally, the Young Bay Mud contains trace amounts of very fine grained sand in small
pockets, small shells, and organic material, including layers of peat. The organic material has weak
to strong H2S odors and gas (likely methane) is known to occur in Young Bay Mud along the San
Francisco Bay Margin. The layer is generally highly plastic and has a very low shear strength (very
soft to soft), except for the base of the Young Bay Mud directly above the Upper Layered Sediments.
This basal layer measuring up to about 5 feet thick is indistinguishable from the overlying soft
Young Bay Mud except for an increase in density and shear strength (soft to medium stiff).
Pocket penetrometer and torvane field readings indicate an apparent undrained shear strength
ranging from 70 pounds per square foot (psf) near the mudline to 1,050 psf near the bottom of the
thicker deposits. The unit dry density varies from 45 to 60 pounds per cubic foot (pcf) with water
content between 70% and 95%.
Upper Layered Sediments underlie the Young Bay Mud and extend from the bottom of the Young
Bay Mud layer to depths varying between 50 and 95 feet below the ground surface, with a layer
thickness between 25 and 55 feet. The Upper Layered Sediments consist of alternating layers of
silty sands, clayey sands, clean and poorly graded sands, sandy to clayey silts and lean to fat clays.
The thickness, sequencing and consistency of these individual layers are highly variable. The silt
and sand interbeds are generally only about 2 to 5 feet thick. A thick unit of granular materials
comprised primarily of sand and sandy gravel/gravelly sand measures up to about 36 feet thick
near the bottom of the proposed Receiving Lift Station (RLS). The granular materials (sands with
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varying amounts of gravel) are in a dense to very dense state with dry densities varying from 105 to
125 pcf. The fine grained materials (silts and clays) have a stiff to very stiff consistency with dry
densities varying from 80 to 110 pcf and water content varying from 21% to 42%. Laboratory
undrained shear strengths vary from 2,150 to 3,350 psf. Pocket penetrometer and torvane field
readings indicate an apparent undrained shear strength ranging from 1,000 to over 4,500 psf, with
occasional soft to medium stiff layers producing strength readings of 500 to 1,000 psf.
Old Bay Deposits underlie the Upper Layered Sediments and extend to at least the bottom of the
deepest investigations performed, a depth of 150 feet below the ground surface (see CPT C-117).
This layer of marine sediments consists of medium stiff to very stiff fat clay and lean to silty clay
with occasional scattered shell fragments. Pocket penetrometer readings indicate an apparent
undrained shear strength ranging from 1,000 to 4,000 psf. Previous investigations of this layer
indicate a dry density of 80 to 90 pcf, with a water content of varying from 30 to 40%.
Groundwater along the project alignment was encountered generally at depths less than 10 feet
below the ground surface, with the level fluctuating in accordance with tidal stages of the adjacent
water bodies. Below the ground surface at varying depths, water-bearing layers of granular soil
materials were encountered within the generally fine-grained layers of clay and silty clay. In most
of the cases, the static groundwater readings within these granular soil layers indicated that the
readings were consistent with the water level in the surface water bodies, indicative of a hydraulic
connection between the deeper granular layers and the ground surface. In some cases, the water-
bearing layers of granular soil are confined by the relatively impermeable fine-grained soils and
may be under artesian pressure conditions.
Specific subsurface conditions at the individual shaft locations are indicated below in the
appropriate sections.
Section 3: Design Criteria
3.1 Shaft Design Criteria
3.1.1 Initial Support Design Criteria The initial support of each shaft will be designed for lateral soil pressure, hydrostatic pressure and
surcharge loads. The lateral soil pressure will be evaluated for at-rest conditions. The hydrostatic
pressure will be determined based on the 100-year flood data. Surcharge loads can be attributed to
construction equipment and storage, traffic loads and adjacent buildings and structures. For
construction and traffic surcharge loads, the most unfavorable configuration will be considered in
design. The surcharge due to existing buildings and structures will be applied according to the
actual location.
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3.1.2 Seismic Design Criteria The project is located between two of the most active major faults in the San Francisco Bay area,
namely the San Andreas Fault to the west and the Hayward Fault to the east. The closest distance
from the alignment to the San Andreas Fault is 4.2 miles and to the Hayward Fault is 19.6 miles.
Both faults are defined as a type "A" by the California Geological Survey (CGS) with a 30-year
probability of an earthquake equal to or greater than magnitude 6.7. A summary of type "A" and
type "B" faults located near the project alignment are presented in the Geotechnical Data Report
prepared by GTC. Based on the United States Geological Survey (USGS) maps, in addition to the
above listed faults, there are other - inferred faults located between San Andreas and Hayward
faults. Based on the United States Geological Survey (USGS) maps, in addition to the above listed
faults, there are other inferred faults located between San Andreas and Hayward faults. There is no
visual evidence or surface features that indicate such faults actually exist; these faults are inferred
to possibly exist based on indirect geologic data such as differences in groundwater elevations.
The seismic analysis of the shafts initial support should be performed using analytical and
numerical approaches. Considering design ground motions, earthquake actions should be
determined from the free-field displacement. These actions should be evaluated numerically using
a one-dimensional free-field site response software (e.g., SHAKE 2000). A two dimensional (2D)
finite element continuum model should also be developed using PLAXIS, FLAC or other applicable
software to assess the longitudinal bending in the shaft lining.
For shaft/tunnel intersection, a simplified 2D analysis should be used. In addition, a three
dimensional (3D) finite element structural model where the ground support would be represented
by dynamic springs should be developed, if necessary (e.g.,using SAP 2000.)
Section 4: Shaft Construction
Different shaft construction methods have been utilized by contractors throughout the country on
similar projects. The most common shaft construction methods include:
Soldier piles and wood lagging (or steel plates)
Liner plates
Precast concrete segments
Conventional shaft sinking with lattice girders and shotcrete
Steel sheet piles
Secant piles
Drilled shafts
Cutter soil mixing (CSM)
Slurry walls
Ground freezing
Caissons
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Selection Criteria
Some of these methods are only suitable for stiff soils, some only suitable for above groundwater
conditions, and some have depth limitations. Initial screening has been performed to eliminate
unsuitable methods and identify a feasible and best suited method for the Gravity Pipeline for
further evaluation.
The initial selection of shaft construction methods for each shaft was mainly based on the following
criteria:
shaft use,
shaft size/shape/depth
soil conditions
groundwater levels
Additional criteria were considered in evaluation of the selected methods and final
recommendations. These criteria include:
shaft structural behavior under assumed loads
shaft construction cost and schedule (SVCW CIP Program criteria)
site restrictions such as:
o the site size
o presence of existing utilities
o airspace protection height limits.
The criteria noted above were used in lieu of the overall SVCW CIP Program criteria, including
maintenance and operations, due to the inapplicability of these criteria for shaft construction
method evaluations. SVCW CIP Program criteria that have been considered include cost, schedule,
and safety. Safety is inherently considered for all shaft construction methods.
The shafts for the SVCW Gravity Pipeline will be constructed in soft ground with a high
groundwater table. Therefore, it has been determined that only relatively impermeable shaft
support systems will be evaluated. As stated in GTC's "Preliminary Characterization of Subsurface
Conditions" Technical Memorandum, groundwater is affected by tidal influence; therefore, no
dewatering will be permitted. Impermeable shaft construction includes gasketed liner plates, sheet
piles, cutter soil mixing, secant piles, slurry walls, ground freezing and caissons. The groundwater
control at the bottom of the shaft is also considered and described in the following sections
individually for each shaft.
The relatively impermeable shaft support system will be a system that minimizes water leakage
into the shaft and prevents lowering of the ground water level outside of the excavation. Maximum
leakage criteria will be established for each shaft during the design stage of the project.
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Gasketed liner plates are applicable in stiff clays or in dense granular soils above the groundwater
level. On the SVCW Gravity Pipeline, water-bearing granular deposits were encountered in Upper
Layered Sediments stratum, in most cases hydraulically connected to adjacent water bodies. In
addition, all shafts will be constructed in Young Bay Mud, which is a very weak layer and needs to
be supported prior to excavation; liner plates do not offer that support. Therefore, liner plates are
not considered a viable option.
Ground freezing is accepted in the industry as the most expensive excavation support method
available. Ground freezing is utilized in extremely difficult conditions where no other excavation
support is feasible, and where cost is generally not a factor. Drilling cost, time for freezing, power to
keep the freeze and refrigeration equipment, all have led to determining ground freezing is an
unnecessary, uneconomical excavation support system based on our experience.
The impermeable options that remain are: steel sheet piles, CSM, secant piles, slurry walls and
caissons. The requirements for the shafts and the soil conditions at each shaft have been considered
and the suitable and cost-effective shaft construction methods selected for evaluation are presented
in Table 4-1.
Table 4-1: Shaft Construction Methods Matrix
Structure
Slurry
Walls
Secant
Piles CSM Sheet Piles Caisson
RLS/Flow
Splitter Shaft
Airport Access
Shaft
San Carlos Drop
Shaft
Bair Island Inlet
Structure
The following section presents general description of the selected shaft construction methods. The
specific evaluations of construction methods for each shaft are covered in subsequent subsections
of Section 4 for the individual shafts.
Slurry walls
Slurry walls consist of rectangular "primary" and "secondary" panels (refer to Figure 4-1) to form
the circular shape of the shaft. The panels extend below the bottom of the shaft and are excavated
with a specially designed clamshell bucket and/or hydromill. Primary panels are typically
subdivided into three segments; the left and the right segments are excavated first and the middle
segment is excavated last. This process requires utilizing bentonite slurry to support the soils as the
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panel excavation progresses. Once the bottom of the panel is reached, the reinforcement cage is
lowered into position inside the panel. Concrete is pumped into the bottom of the excavation
through vertical pipes called tremies thus replacing the slurry with concrete. Slurry is circulated at
regular intervals throughout the construction period through a slurry plant where the slurry is
cleaned and de-sanded. The secondary panels are constructed between primary wall panels with
milling joints in previous constructed primary panels. After all slurry walls are completed and the
concrete allowed to cure, excavation begins to remove the soil from the interior of the shaft.
Figure 4-1: Slurry Wall Circular Shaft
Secant piles
Secant pile walls are formed by constructing a series of overlapping “primary” and “secondary”
concrete-filled drilled holes to form a circular shape of the shaft (refer to Figure 4-2). The primary
piles are constructed first, followed by secondary piles, which are cut into the previously placed
primary pile concrete. The amount of overlap required between the adjacent piles is a function of
the structural design requirements and the achievable installation tolerance.
There are two (2) methods typically used to install secant piles: the dry hole and the wet hole
methods. The dry hole technique includes using a temporary heavy wall drill casing, advanced
concurrently with the drill tool. Once the bottom of the pile is reached, concrete is pumped and as
the concrete level rises, the casing is removed. The wet hole technique, similarly to the slurry walls
excavation method, utilizes slurry to ensure the stability of the drilled hole before the concrete is
pumped through vertical tremie pipes.
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The concrete chosen for primary piles will often have lower strength with a slower rate of setting in
order to ease the cutting of secondary piles into primary piles. The concrete of the secondary piles
will have higher design strength and may be reinforced with reinforcing cages or steel beams.
Figure 4-2: Secant Pile Circular Shaft
Cutter soil mixing (CSM)
This method involves mixing cement with the existing soil around the perimeter of the shaft to form
a continuous wall conforming to the configuration of the shaft. The CSM extends below the bottom
of the shaft. The CSM wall produces a relatively impermeable wall and permits only minor water
leakage.
The strength of the soil mix wall depends heavily on the existing soils being mixed and the cement
replacement ratio. The cement replacement ratio refers to the percentage of the soil being replaced
with cement. Higher replacement ratios typically result in greater strengths of the soil mass.
However, the achievable strengths of the cutter soil mix are considerably lower than in slurry or
secant pile walls. Consequently, the CSM wall support system for deeper shafts very often requires
additional structural support elements such as a layer of reinforced shotcrete placed against the
interior of the excavated wall in circular shafts, or steel shapes embedded in the walls with shaft
internal bracing in rectangular shafts (refer to Figure 4-3). This cement-soil mixture provides a
stabilized wall (around the perimeter of the shaft) of sufficient strength to allow the interior of the
shaft to be excavated in phases. A structural support system is constructed as excavation
progresses.
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Figure 4-3: CSM Circular Shaft
Sheet Piles
This method utilizes steel structural sections with a vertical interlocking system that can be used to
create shaft walls; the interlocking system ensures the steel sections remain connected. Steel
sheeting is effective in minimizing or nearly eliminating water from entering the shaft. The sheet
piles are typically driven, vibrated in place, or pressed in, depending on the type of soil and noise or
vibration restrictions in the construction area. Once the sheet piles are in place, excavation of the
soil from the inside the shaft can commence. As excavation proceeds utilizing standard soil
excavation techniques, additional structural members may be installed as required. In circular
shafts, steel or concrete ring beams may be installed to provide additional internal support. For
rectangular excavations, a system of steel wales and struts provide the required support for the
walls (refer to Figure 4-4).
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Figure 4-4: Sheet Piling Circular Shaft
Caisson
This method utilizes reinforced concrete sections for the construction of the shaft. The sections are
constructed at the surface to conform to the specified shaft configuration and lowered in place
using self-weight or hydraulic jacks (as required) that control the rate of movement. Typically, the
sections are lowered by slightly overcutting the soils below the cutting edge located at the bottom
of the first segment or by jacks pushing the sections into the ground by adding a vertical force to the
self-weight of the concrete. In very soft soils such as the layer of the Young Bay Muds, the jacks
would suspend the segments and lower them into the ground. Caissons are either installed in-the-
wet or in-the-dry. Shafts that are constructed in-the-wet are filled with water on the inside.
The construction of the caisson shaft commences with the excavation of the shaft area for a depth of
a few feet and the construction of the concrete collar. Concrete collars are constructed to guide the
placement of the concrete sections, to keep the sections vertical and to resist the forces from the
hydraulic jacks. The collars may require pile or other supports, depending on the soils at the shaft
location.
There are three (3) types of concrete sections: precast, segmental precast and cast-in-place
concrete. In each method, the first section is equipped with a steel cutting edge at its bottom to aid
the caisson sinking. The sections are lowered into the ground and the soil is removed from within
the caisson as the construction progresses.
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Precast concrete sections are cast monolithically to the shape of the shaft and have only horizontal
joints between each unit. They are constructed at a precasting plant or onsite in a casting facility
and transported to the shaft location. Typically, precast caissons are suitable for smaller diameter
shafts due to the limitation of the lifting weight and difficulty in transporting larger diameter
sections.
Segmental precast sections have horizontal joints between each section of the shaft lining as well as
vertical joints along the circumference of the shaft. They can be constructed in a precast facility on
or off site. Each full circumferential element is assembled at the shaft location, connected with bolts
at the vertical joints and with tie rods at the horizontal joints. When each section is completed, the
entire shaft is lowered in place and the next section is assembled on top of the previous section.
This process continues until the design depth of shaft is achieved.
The cast-in-place sections have only horizontal construction joints between vertical sections (refer
to Figure 4-5). They are reinforced and formed at the perimeter of the shaft configuration. The
cast-in-place sections are cast one section on top of the other around the perimeter of the shaft to
the shape specified. The first section of the cast-in-place caisson is set on top of the cutting edge and
then lowered in place after it achieves the prescribed strength. Subsequent sections are reinforced,
formed and lowered into the ground until the shaft is complete.
If a high groundwater table is present, gaskets for precast caisson sections or water stops for cast-
in-place caisson sections can be used to provide watertight joints between concrete segments. For
the SVCW Gravity Pipeline, due to the artesian water conditions, it is anticipated that gaskets will be
required.
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Figure 4-5: Construction of Cast-In-Place Caisson Shaft
4.1 Receiving Lift Station
4.1.1 Site Geology The information about general subsurface conditions at the Receiving Lift Station (RLS) is based on
the Phase I subsurface exploration program performed by Geotechnical Consultants Inc., and its
findings are presented in the "Preliminary Characterization of Subsurface Conditions" Technical
Memorandum dated December 9, 2015.
The existing subsurface conditions at the RLS were developed from four borings taken at the
proposed shaft location (B-101, B-109P, B-113P and B-114P), in addition to field and laboratory
test results performed on selected soil samples. The maximum boring depth obtained was 121.5
feet below the ground surface, approximately 55.5 feet below the bottom of the RLS. Piezometers
were installed at boring locations B-109P, B-113P and B-114P with screens located within the
Upper Layered Sediments.
The results from the boring program indicate that Artificial Fill covers the site to a depth of 3 to 6
feet below the ground surface and varies from clay to silt with varying amounts of sand/gravel.
Varying quantities of organic materials, cobbles and debris may be encountered within the fill.
Young Bay Mud underlies the fill with a layer thickness between 45 and 50 feet. The Young Bay
Mud consists of very soft to soft, highly compressible and plastic, near normally consolidated fat
clay. Zones of trace to abundant shell fragments, organic materials and occasional thin layers of
peat (less than a few feet in thickness) are contained within this layer. Standard Penetration Test
(SPT) results generally were "weight of rods" (WOR). Pocket penetrometer field readings indicate
an apparent undrained unconfined compressive strength ranging from 140 to 1,200 pounds per
square foot (psf). Laboratory shear test results varied from 181 to 390 psf. The unit dry densities
were in the 47 to 56 pcf range, with water content between 73% and 94%. The liquid limits and
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plastic limits laboratory test results for the clay varied from 65% to 90% and 28% to 36%,
respectively. Consolidation tests were performed on selected samples of Young Bay Mud.
Below the Young Bay Mud are the Upper Layered Sediments. These sediments contained a layer
thickness varying between 40 and 48 feet. The soil deposits consists of a complex alternating layers
of silty sands, clayey sands, clean and poorly graded sands, sandy to clayey silts and lean to fat
clays. The thickness, sequencing and consistency of these individual layers are highly variable. SPT
results ranged from 16 to 50 blows/foot. The granular materials (sands with varying amounts of
gravel) are in a dense to very dense state. The fine grained materials (silts and clays) have a stiff to
very stiff consistency. A liquid limit of 30% and plastic limit of 19% were obtained on one clay
sample tested in the laboratory. Pocket penetrometer field readings indicate an apparent undrained
unconfined compressive strength ranging from 2,000 to over 5,400 psf.
Old Bay Deposits underlie the Upper Layered Sediments and extend to at least the bottom of the
deepest boring performed at this shaft site, a depth of 121.5 feet below the ground surface. This
layer of marine sediments consists of medium stiff to very stiff fat clay and lean to silty clay with
occasional scattered shell fragments. SPT results ranged from 26 to 33 blows/foot. Pocket
penetrometer readings indicate an apparent undrained compressive strength ranging from 1,000 to
4,000 psf.
Groundwater was encountered within the first few feet below the ground surface at Boring B-101
and was observed to be influenced by tidal fluctuations. Static water levels within the installed
piezometers were at elevation 104.5 which correspond to 1.5 feet above the ground surface
reflecting artesian pressure conditions within this confined aquifer (deep granular layer within
Upper Layered Sediments).
4.1.2 Shaft Excavation 4.1.2.1 Excavation Size and Configuration The final interior of the Receiving Lift Station (RLS) will be comprised of three sections: inlet
channels consisting of two gates and two channels, an ogee ramp and a wet well. Two distinct shafts
are envisioned for the installation of the final shaft interior, including the Flow Splitter and the RLS.
The Flow Splitter Shaft, as a final structure, would serve to receive flows and house gate controls
prior to flows entering the RLS Shaft. The shaft would be also used for the retrieval of the Tunnel
Boring Machine (TBM) and would require a minimum 25-foot internal diameter to accommodate
the retrieval. The RLS Shaft would serve as the lift station where the wastewater from the tunnel
would be pumped up to the plant level for treatment. Both shafts would be constructed by the PDB,
but finished and equipped by others. The two distinct shafts will allow two separate PDBs (Gravity
Pipeline and the Front-of-Plant) to work simultaneously in each space for the duration of the TBM
removal (estimated to be about 6 weeks).
The size of the RLS has not been determined yet and will mainly depend on the final size of the shaft
interior and the selected shaft configuration. It is currently anticipated that the Flow Splitter Shaft
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will be approximately 68-feet deep with a diameter between 25 and 32-feet. The RLS Shaft will be
approximately 84-feet deep and its diameter will be between 28.5 and 52-feet.
The following four configurations were evaluated for the RLS:
1. Two separate shafts with a connection made near the bottom to connect the Flow Splitter
Shaft with the RLS Shaft.
2. One large circular shaft with a baffle wall separating the Flow Splitter Shaft and the RLS
Shaft.
3. Two shafts adjacent to each other forming a figure “8” with a baffle wall in-between.
4. Oval shaft with the baffle wall separating the Flow Splitter Shaft and the RLS Shaft.
One circular shaft configuration was eliminated from further consideration due to larger footprint
and anticipated higher cost as compared to the other options. The remaining configurations: two
separate shafts with a connection made near the bottom, figure "8"and oval shapes are represented
in Figure 4-6 to Figure 4-9, respectively.
Figure 4-7 below displays the first figure "8" configuration based on which a conceptual structural
evaluation was performed. The following Figure 4-8 represents the most recent figure "8"
configuration considered and revised based on the latest dimensions of the RLS Shaft interior.
However, the final size of the shaft interior has not been determined yet and the shaft configuration
depicted in the Figure 4-8 is presented for reference only and could be subject to further changes.
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Figure 4-6: Two Separate Shafts with Connection Tunnel Configuration
Figure 4-7: Figure Eight Shaft Configuration (As Evaluated In This Memorandum)
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Figure 4-8: Figure Eight Shaft Configuration (As Recently Considered)
Figure 4-9: Oval Shaft Configuration
4.1.2.2 Excavation Methods Conventional soil excavation techniques such as a crane and a clamshell bucket or an excavator can
be utilized to excavate the materials within the shafts. The shaft may be excavated in wet or dry
conditions. This will depend on the type of impervious system selected, as described in the
following sections. Under wet conditions, the shaft would be flooded and the excavation would be
performed underwater with a crane using clamshell bucket. Under dry conditions, it is envisioned
that an excavator and buckets hoisted to the surface by a crane would be used.
4.1.3 Initial Support 4.1.3.1 Support Methods and Evaluation Three configurations are envisioned to be suitable for the construction of the RLS: figure "8", oval
and two separate shafts with a connection tunnel in-between. A conceptual structural design was
performed for the RLS in the configuration of the figure "8" and oval to assess the structural
behavior of the shaft under assumed loads and approximate the required sizes of the structural
elements for the initial support. The two separate shafts with a connection tunnel in-between
configuration was added for the detailed evaluation at a late stage in development of this
memorandum. Therefore, no conceptual design was performed for this configuration at this time
and all information presented in this memorandum is based on engineering experience and
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judgment. Further evaluation of the two separate shafts configuration is recommended during the
preliminary design stage.
Due to soil conditions as defined by GTC in the "Preliminary Characterization of Subsurface
Conditions" Technical Memorandum, high groundwater levels and the shaft configuration, only
three initial support methods have been considered for the RLS construction, namely: slurry walls,
secant piles and caisson. The CSM was excluded because of its relatively low strength as opposed to
concrete for applications of this depth and size. The CSM wall is constructed by mixing cement with
the natural soil. The soil conditions at the RLS consisting of a thick layer of clay would produce a
wall with relatively low strength typically ranging from 400-900 pounds per square inch (psi).
Therefore, utilizing the CSM initial support method would require installation of additional
structural supporting elements, such as a reinforced concrete lining or internal bracing with steel
shapes embedded in the wall making this option more costly and difficult. The sheet piling option
was also found to be not suitable, because the shaft depth and the extremely heavy size of internal
bracing.
The following assumptions have been made in the conceptual design: 5 feet of the shaft would be
constructed in very soft Artificial Fill, 45 feet in very soft Young Bay Mud and 16 feet in dense to
very dense Upper Layered Sediments. The Upper Layered Sediments consist of varying quantities of
sands, gravels and clays, and the RLS shafts will terminate in a water-bearing sand layer. The shafts
would be subjected to 68 feet of hydrostatic head measured from 1.5 feet above the surface
elevation to the bottom of the shaft. The interior dividing wall in the final structure, in addition to
axial loads, will be capable of resisting bending moments from the potential difference in water
level in the Flow Splitting and RLS Shafts. These assumptions were based on the initial RLS
information available, and will be reviewed to reflect the most recent dimensions during the
preliminary design stage.
The results of the conceptual design indicate that the oval shaft configuration is not suitable for the
RLS. A bending moment would develop in the shaft lining along the longer sides of the shaft, which
would require continuous structural reinforcement in the horizontal direction. Continuous
reinforcement can only be provided in the cast-in-place caisson option since secant piles can only
be reinforced in the vertical direction and slurry walls and caisson precast concrete elements have
reinforcement discontinuity at vertical joints between panels. Consequently, construction of the
shaft utilizing slurry walls, secant piles or caisson precast concrete elements may not be feasible for
this Gravity Pipeline without internal bracing such as wales and struts. This would be costly and
would require a longer schedule. As for the cast-in-place caisson walls, they would have to be
heavily reinforced to resist the anticipated bending moments. Moreover, using the oval shape
would provide an additional cross sectional area inside of the shaft, which is not needed for the
final structure and would only increase the cost of the shaft excavation and backfilling for the
construction of channels.
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Therefore, for the RLS structure, the two separate shafts with a connection tunnel at the bottom and
figure "8" configuration are recommended and considered in further evaluation of the initial
support system. The following are summaries of the applicability of each of the remaining
excavation support systems for the RLS.
Slurry walls
Based on the conceptual design of the RLS in the figure "8" configuration, it is anticipated that, as a
minimum, 3-foot thick reinforced concrete slurry walls would be required for both the 32 foot
diameter Flow Splitter Shaft and 52-foot diameter for the RLS Shaft (refer to Figure 4-10). The
structure will consist of a baffle wall in-between the two RLS Shafts. Two methods are envisioned
for the baffle wall construction; slurry walls or cast-in-place. Selection will mainly depend on the
magnitude of the differential pressures in the two shafts. The wall could simply be constructed
from slurry wall panels before the excavation begins. This option would be desirable if no
differential pressures in the two shafts are anticipated. Otherwise, a supplementary wall will need
to be constructed to provide continuous horizontal reinforcement or another wall construction
methods utilized. The other method would include the installation of a cast-in-place wall. The shaft
could be excavated with or without the cast-in place wall. In the latter option, temporary struts at
the wall location would be required for stability during excavation before the wall is casted.
Alternatively, the wall can be constructed as cast-in-place reinforced concrete in vertical segments
as the excavation progresses. However, this method would reduce the progress of the shaft
excavation since the concrete in the baffle wall will have to achieve the required compression
strength before excavation resumes.
It is anticipated that, for the two separate shafts configuration, minimum of 2 feet 6 inches thick
reinforced concrete slurry walls will be required. A connection structure would be constructed in-
between the two RLS shafts (refer to Figure 4-11). Methods of construction of the connection
structure were not evaluated at this time. For the cost estimating purposes, a hand mined tunnel
with jet grouting soil improvement at the tunnel level was assumed. The hand tunneling is typically
performed by tunnel miners using compact equipment or hand tools to excavate the soils. The
improvement of the soils would enhance the soil stand up time providing stable working conditions
and minimizing water inflow during excavation. A more detailed evaluation of the construction
methods of the connection structure will be performed by the PDB.
For both configurations, an additional, cast-in-place reinforced concrete wall may be required at the
tunnel breakout to prevent infiltration and resist the anticipated breakout forces. The breakout wall
may be demolished after the tunnel is completed as required for the final shaft interior. Since the
TBM has to penetrate the slurry walls, fiberglass reinforcement will be used at the tunnel eye in lieu
of steel bars. A mud slab would be poured at the Flow Splitter Shaft invert to provide smooth and
firm working surface for the activities taking place in the shaft.
Also, for both configurations, due to the presence of water-bearing granular layers at the tunnel
level, soil improvement will be implemented for ground treatment at the tunnel breakout. This will
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minimize water infiltration into the Flow Splitter Shaft during TBM breaking in for retrieval. As an
additional protection measure, a seal around the tunnel breakout inside of the shaft will be installed
to aid in minimizing or eliminating groundwater inflow into the shaft.
The slurry wall would provide a relatively impermeable shaft lining and could serve as a permanent
lining for the RLS shafts capable of withstanding the long-term permanent loads. The installation of
a corrosion protection layer will be determined by others.
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Figure 4-10: Slurry Wall Alternative – Figure "8"Configuration
Figure 4-11: Slurry Wall Alternative – Two Separate Shafts Configuration
Secant piles
It has been determined that, for the RLS in figure "8" configuration, approximately 4 foot diameter
unreinforced concrete piles would be required to resist the circumferential compression generated
around the shaft and to accommodate any vertical pile deviations (refer to Figure 4-12). Similarly
to the slurry wall option, the baffle wall could be constructed utilizing secant piles at the same time
as the shaft walls or cast in place either after or simultaneously with the shaft excavation. The
selection of the construction method for the baffle wall will depend mainly on the magnitude of the
differential pressures. Some of the piles, especially those in the vicinity of the baffle wall connection
between the circular shafts, would have to be reinforced to resist the forces at the intersection and
facilitate the wall construction if the cast-in-place option is selected.
It is anticipated that for the two separate shaft configuration, a minimum of 3.5 foot diameter
unreinforced concrete piles would be required to resist the circumferential compression generated
within the initial support and accommodate any vertical pile deviations (refer to Figure 4-13).
Similarly, to the slurry wall option this shaft configuration will require the construction of a
connection structure.
For both configurations, the secant pile wall may require an additional cast-in-place reinforced
concrete wall to resist forces at the tunnel breakout. The piles adjacent to the tunnel will be
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reinforced to aid in resisting the forces on the side of tunnel breakout. At the breakout location,
where the TBM will penetrate the secant piles, fiberglass reinforcement will be used at the tunnel
eye in lieu of steel bars. The breakout portion of the wall inside the shaft may be demolished after
the tunnel is completed as required for the final shaft interior.
A mud slab would be poured in the Flow Splitter Shaft (the TBM retrieval location) invert to
provide smooth and firm working surface for the activities taking place in the shaft. Similarly to the
slurry wall option, soil improvement and a seal at the tunnel breakout will be used to prevent
groundwater ingress into the shaft during breaking for the TBM retrieval.
The secant pile shaft support could be designed to serve as a permanent structure for the RLS and
the Flow Splitter Shafts since the secant piles are capable of withstanding the long-term permanent
loads the structure will be subject to. However, the large number of joints in the secant pile wall
would make the system more susceptible to water infiltration. A layer of fiber reinforced shotcrete
would enhance the impermeability of the system. The installation of a corrosion protection layer
will be determined by the PDB in collaboration with SVCW.
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Figure 4-12: Secant Piles Alternative – Figure "8" Configuration
Figure 4-13: Secant Piles Alternative – Two Separate Shafts Configuration
Caisson
For the Caisson option, it is envisioned that approximately 3-foot thick concrete walls would be
required (refer to Figure 4-14) for the RLS in figure "8" configuration and approximately 2-foot
thick walls for the two separate shafts configuration (refer to Figure 4-15). The shaft lining would
be constructed at the surface, in vertical sections, and then lowered into the ground while
excavation progresses.
For the figure "8" configuration, the caisson would be constructed from cast-in-place concrete. It is
anticipated that the precast type of caisson will not be applicable to the RLS in figure "8"
configuration due to the large size of the shaft and its shape. Therefore, this option was not
investigated further. However, for the two separate shafts configuration, both options are viable.
This caisson construction would start with an excavation and installation of a cast-in-place concrete
collar which would provide support for the surcharge loads at the surface, resist the forces from
hydraulic jacks, and act as a guide for shaft sinking. Due to soil conditions at the RLS, it is
envisioned the collar would have to be supported by series of vertical piles or other supports
extending down to the Upper Layered Sediments or even deeper to the Old Bay Deposits stratum.
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Hydraulic jacks (strand jacks with cables) would suspend each section of the structure in the Young
Bay Mud and lower it into the ground as excavation progresses. Once the Upper Layered Sediments
are reached, the caisson self-weight and overcutting of the soil slightly below the cutting edge is
anticipated to be utilized in order to sink the shaft. The usage of jacks for pushing of the caisson
segment is not envisioned. However, the final procedure will depend on the PDB's selected means
and methods of shaft construction.
The precast concrete segments, if utilized for the two shaft configuration, would be cast on or off
site and transported to the shaft location. There, they will be assembled around the circumference
of the shaft to form a complete circle. Each vertical joint would be connected with bolts. Tie rods
will be used to connect segments in horizontal joints. After the completion of a full section, it would
be lowered in place by the use of hydraulic jacks. The area within the caisson would be excavated
and the next caisson section would be assembled. This process would continue until the shaft is
completed.
The cast-in-place concrete sections would be constructed at the shaft final location. They would be
reinforced, formed and cast to follow the configuration of the shaft. The shaft would be constructed
in vertical lifts with water stops at each construction joint. The joints would be doweled to provide
continuous reinforcement in the lining of the shaft. Similarly to the precast segments, the cast-in-
place sections would be lowered evenly into the ground aided by hydraulic strand jacks, the area
within the circumference would be excavated as the shaft is lowered into the ground and the cycle
repeated.
It is anticipated that the dividing wall in figure "8" configuration will be constructed simultaneously
with the shaft walls. The construction type of the baffle wall would follow the construction type of
the main outside walls; cast-in-place.
Similarly, to the other options, soil improvement and a seal at the tunnel breakout will be used to
prevent groundwater ingress into the shaft during breaking for the retrieval of the TBM. For both
shaft configurations, an additional, cast-in-place reinforced concrete wall may be required at the
tunnel breakout to resist the anticipated breakout forces. The breakout wall may be demolished
after the tunnel is completed as required for the final shaft interior. At the breakout location, where
the TBM will penetrate the caisson wall, fiberglass reinforcement will be used at the tunnel eye in
lieu of steel bars. A mud slab would be poured at the Flow Splitter Shaft invert to provide smooth
and firm working surface for the activities taking place in the shaft.
The caisson would provide relatively impermeable walls, which could serve as a permanent lining
for the RLS Shafts capable of withstanding long-term permanent loads. The installation of a
corrosion protection layer will be determined by the PDB in collaboration with SVCW.
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Figure 4-14: Caisson Alternative – Figure "8" Configuration
Figure 4-15: Caisson Alternative – Two Separate Shafts Configuration
Groundwater control at RLS
Only an impermeable shaft support system will be utilized for the RLS construction. Since the shafts
will be terminated in water-bearing granular soils with artesian conditions, the construction of a
sealing element at the shaft invert would be required to minimize water inflow into the excavation
and facilitate construction. The sealing element at the shaft invert in conjunction with the
impermeable excavation support would provide a relatively impervious system minimizing the
groundwater inflow into the structure. The following six (6) options of impervious systems have
been investigated:
Option 1 - Extended initial support
This system would include the extension of the excavation support into the impermeable layer
(refer to Figure 4-16). The linings of the Flow Splitter and RLS Shafts would be extended
approximately 34 feet and 18 feet respectively down through the permeable layers of the Upper
Layered Sediments into the lower relatively impermeable clays of the Old Bay Deposits to provide a
water cut-off barrier.
This option would minimize the water inflow into the excavation during the construction of the RLS
structure and provide a short term relatively impermeable barrier, adequate during construction.
However, with time, the hydrostatic pressure would build up at the invert of the RLS structure and
the installation of permanent groundwater control system would be required. Two (2) options are
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envisioned for the permanent groundwater control at the RLS invert: a structural slab designed to
resist the hydrostatic pressure or drainage holes penetrating the final invert interior to relieve the
pressure.
Figure 4-16: Extended Excavation Support
The advantages and disadvantages of this system are listed in Table 4-2.
Table 4-2: Advantages and Disadvantages – Option 1
Advantages Disadvantages
Fast installation since only the support
will be extended
Permanent groundwater control system at
invert of RLS would be required
Reliable system Not suitable with caisson excavation
support method
Relatively low cost since equipment
will be onsite
Not recommended for secant pile method
as the system would reach its practical
depth
Allows for relatively dry excavation
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Option 2 - Excavation support and permeation grouting curtain
In lieu of extending the excavation support into the impermeable layer, a water cut-off barrier could
be constructed utilizing permeation grouting (refer to Figure 4-17). The permeation grouting
would be accomplished from the surface before the excavation of the shafts begins. Two grout
placement methods could be used. A series of grout holes could be drilled along the shaft perimeter
through grout pipes embedded in the excavation support. A low viscosity grout would be injected
into in-situ soil at relatively low pressures allowing the grout to permeate into the soils. The
permeation grouting was selected for this option as it suits the ground conditions well at the
bottom of the RLS (consisting of sands and gravels) and it is the simplest and least expensive
grouting method. Another type of soil improvement could be utilized in lieu of permeation grouting,
such as jet grouting or soil freezing. However, it is anticipated that the cost of these systems would
be much higher than permeation grouting or extended excavation support (Option1). Therefore,
they are not recommended at this time. The additional soil improvement methods (jet grouting and
soil freezing) may be revisited during preliminary design if determined that they are best suited for
the construction of the shaft.
The excavation support and permeation grouting curtain option would minimize the water inflow
into the shafts during construction; however, it would require substantially more labor and cost for
verification (testing) than Option 1. Similarly, this option would require the installation of a
permanent groundwater control system in the invert of the RLS. Therefore, the excavation support
and permeation grouting curtain option is not recommended and excluded from further
investigation.
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Figure 4-17: Permeation Grouting Curtain
The advantages and disadvantages of the system are listed in Table 4-3.
Table 4-3: Advantages and Disadvantages – Option 2
Advantages Disadvantages
Suitable with all three excavation
support methods
Permanent groundwater control system at invert
of RLS would be required
Good shaft foundation
Substantially more labor and verification
(testing) necessary to ensure system constructed
as designed
Mobilization of grouting equipment at the surface
is required
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Option 3 - Excavation support with gravity concrete plug
This system would include the installation of an impermeable excavation support and a sealing
element consisting of a concrete gravity plug (refer to Figure 4-18). It is estimated that a 48 and
60-foot thick gravity concrete plugs are required to resist the hydrostatic pressure at the invert of
the Flow Splitter and RLS Shafts respectively. Since the impermeable layer is only 28 and 12 feet
below the shaft inverts, the additional 20 and 48-feet of concrete plug will not be required through
this layer to achieve a relatively impermeable system for the construction of the RLS Shafts. The
system will require the initial support to extend below the bottom of the plug to ensure stability of
the excavation before pouring in the concrete plug. It would also require excavation of the soils
inside of the shaft for the plugs construction. The plugs would work as a groundwater cut–off
barrier and a final slab for the RLS.
The extension of the shaft initial support system and the excavation to accommodate the concrete
plug construction would make this option costly. Therefore, the impermeable excavation support
with gravity concrete plug option is not recommended and is excluded from further investigation.
Figure 4-18: Concrete Plug
The advantages and disadvantages of the system are listed in Table 4-4.
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Table 4-4: Advantages and Disadvantages – Option 3
Advantages Disadvantages
Suitable with all three excavation
support methods
Extension of the initial support system
required
Permanent groundwater control
system at RLS invert not required
Excavation of the inside of the shaft for
the plug construction required
Expensive option overall
Longer shaft construction duration
Option 4 - Excavation support with jet grouting gravity plug
This system would consist of the installation of an impermeable excavation support system and a
sealing element consisting of a jet grouting gravity plug (refer to Figure 4-19). The jet grouting will
be performed from the surface before the excavation of the shafts begins. The jet grouting
technique injects grout at a high pressure and velocity destroying the soil structure and mixes grout
and soil to form a homogeneous impervious mass.
The 28 and 12-feet thick jet grout plugs in conjunction with the impermeable excavation support
will function as a sufficient impervious system during construction of the RLS Shafts. As for the final
structure, the installation of permanent groundwater control system to accommodate potential
hydrostatic pressure that could develop in the future behind the invert of the structure might be
required. In lieu of the permanent groundwater control system, additional grouting of the plug
could be performed to make the jet grouting plug completely watertight and suitable for an
impermeable final invert. The plug would also provide an excellent foundation for the structure.
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Figure 4-19: Jet Grouting Plug
The advantages and disadvantages of the system are listed in Table 4-5.
Table 4-5: Advantages and Disadvantages – Option 4
Advantages Disadvantages
Suitable with all three excavation support
methods
Permanent groundwater control
system at structure invert might
be required
Provides excellent foundation for the RLS walls Expensive option overall
Could serve as a permanent groundwater
control system if additional grouting of the
plug is performed to make the jet grouted plug
completely watertight
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Option 5 - Excavation support with structural concrete invert slab
This system would include the installation of an impermeable excavation support system and a
sealing element consisting of a structural concrete invert slab (refer to Figure 4-20). The dividing
wall and the impermeable excavation support system would need to be installed simultaneously, so
there would be an adequate amount of weight to resist buoyancy after installation of the invert slab.
The structural concrete invert slab would be a minimum of 8-foot thick with steel reinforcement
and would be designed for artesian hydrostatic uplift pressures.
The installation process requires flooding of the shaft to counterbalance the hydrostatic uplift
pressures. The excavation to the bottom of the impermeable excavation support system would be
performed underwater. Once excavated, the invert slab reinforcement and connections to the
impermeable excavation support system would be installed by underwater divers. The concrete
would then be installed using the tremie concrete placement method. This impervious system
would be considered as part of the final structure and would not require installation of
supplementary groundwater control system.
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Figure 4-20: Structural Concrete Slab
The advantages and disadvantages of the system are listed in Table 4-6.
Table 4-6: Advantage and Disadvantage – Option 5
Advantages Disadvantages
Permanent groundwater control
system at structure bottom not
required
Installation of middle wall and approximately 8
feet thick slab required to resist buoyancy
Not recommended with secant pile wall system,
as it would be difficult to key the structural slab
into the secant piles, which makes the option
more costly
Option 6 – Caisson with jet grouting water cutoff curtain
In this option, a water cut-off curtain constructed utilizing jet grouting (refer to Figure 4-21) would
be extended through the permeable layers of Upper Layered Sediments into the lower relatively
impermeable clays of the Old Bay Deposits.
The jet grouting will be performed from the surface around the perimeter of the RLS structure prior
to the excavation. The jet grouting technique injects grout at a high pressure and velocity breaking
down the soil structure and mixes grout with the soil to form a homogeneous impervious mass. The
jet grouting curtain will provide water cut-off barrier and act as a support for the concrete collar
required for the caisson installation.
As for the final structure, the installation of permanent groundwater control system to
accommodate potential hydrostatic pressure that could develop in the future behind the shaft final
interior would be required.
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Figure 4-21: Caisson with Jet Grouting Water Cutoff Curtain
The advantages and disadvantages of this system are listed in Table 4-7.
Table 4-7: Advantages and Disadvantages – Option 6
Advantages Disadvantages
Allows for relatively dry excavation Permanent groundwater control system at
invert would be required
Provide excellent support for the
concrete collar around the shaft.
Impermeable systems comparison cost
Relative comparison costs for the RLS impermeable system options are shown in Table 4-8 and 4-
9. The costs were developed in 2015 prices. Mark-up of 25 percent for indirect cost and 15 percent
for overhead and profit are included in the costs. The costs do not include contingency and
escalation. Refer to Appendix A.
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Table 4-8: RLS Impermeable System Cost Comparison - Figure "8" Configuration
Initial
Support
Method
Option 1:
Initial Support +
Extended Initial
Support Cost
(Millions)
Option 4:
Initial Support +
Jet Grouting Plug
Cost
(Millions)
Option 5:
Initial Support +
Structural
Concrete Slab
Cost
(Millions)
Option 6:
Caisson with Jet
Grouting Curtain
Cost
(Millions)
Slurry walls $5.5 $6.5 $5.9 N/A
Secant piles $5.0 $5.8 $5.7 N/A
Caisson N/A $7.0 $6.4 $8.2
Table 4-9: RLS Impermeable System Cost Comparison - Two Separate Shafts Configuration
Initial
Support
Method
Option 1:
Initial Support +
Extended Initial
Support Cost
(Millions)
Option 4:
Initial Support +
Jet Grouting Plug
Cost
(Millions)
Option 5:
Initial Support +
Structural Concrete
Slab Cost
(Millions)
Option 6:
Caisson with Jet
Grouting Curtain
Cost
(Millions)
Slurry walls $5.8 $5.8 $5.5 N/A
Secant piles $5.3 $5.2 $5.3 N/A
Caisson N/A $6.8 $6.4 $7.8
4.1.4 Site Conditions The RLS Shaft and Flow Splitter Shaft site would be located east of the Redwood Shores Parkway
and Radio Way intersection, in Redwood City. The shaft site would be located on SVCW property,
adjacent to the existing WWTP. This site will serve as the location for the Receiving Lift Station
(RLS) Shaft and Flow Splitter Shaft. The Flow Splitter Shaft will ultimately be used for channelizing
flow upstream of the RLS which will be constructed within the RLS Shaft.
Areas adjacent to the site will be used for construction of various SVCW Conveyance System
Program Front of Plant (FOP) wastewater facilities including headworks, flow diversion structure,
and odor control facilities. FOP facilities including the RLS inside the RLS Shaft are being designed
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by others. Due to the various facilities to be designed and constructed by multiple entities, close
coordination of site staging for different phases of construction at this location is required.
4.1.4.1 Site Ingress/Egress Access to the site would be from Radio Road via Redwood Shores Parkway. The site location and
access to/from the site from Highway 101 and surrounding areas is shown in Figure 4-22.
Figure 4-22: RLS and Flow Splitter Shaft Site Ingress and Egress
Specific ingress/egress gate location and access requirements within the site for construction
vehicles is considered in the site staging requirements for the site and is discussed in further detail
in Section 4.1.4.3.
4.1.4.2 Existing Site Conditions The RLS and Flow Splitter Shafts site would be installed in an area that has historically been used for
an ornamental pond within the SVCW WWTP property. As a result of the historical use of the
property, there are currently no known surface utilities or other existing features within the shaft
site area. There is an elevated corridor adjacent to the site, along the northern site boundary, that
contains various subsurface utilities. Existing recycled water facilities are located within this
corridor. Other utilities including electrical, sewer, gas, communication and storm drain facilities
are located adjacent to the site along Radio Road.
Shaft Construction Site
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Planning Level Technical Memorandum No. 4
Shaft Construction
4.1.4.3 Staging Area Requirements The site area will need to be drained of water prior to construction and cleared of vegetation. As a
result of the historical use of the site and soft bay mud soil conditions, the site will require
stabilization consisting of lime treatment in some areas (permanent paving for FOP facilities) and
reinforcing fabric for subgrade stabilization in other areas (temporary construction staging areas).
The site elevation will be graded and will receive a layer of base rock to provide an all-weather
surface for construction.
There will be two phases of construction activities related to tunneling and shaft construction at
this location. The first phase will be construction of the shafts and the second phase will be
retrieval of the TBM at this location. The required staging area for each phase is as follows:
Flow Splitter Shaft and RLS Shaft Construction: Approximately 2.5 Acres (including
common access entrance area, fenced in site area approximately 2.3 Acres)
TBM Retrieval: Approximately 0.4 Acres
The following have been considered in developing the Flow Splitter Shaft and RLS Shaft
construction staging area requirements:
Shaft Location relative to overall staging area
Shaft excavation size, configuration and potential excavation method
Site access from public right-of way
Design Vehicle Type: WB-50 (semi-trailer combination)
Shaft Excavation Rate: Approximately 4 vertical linear feet (VLF) per day
Excavated Material Storage: 3-day (7,200 sf)
The staging plan for the Flow Splitter Shaft and RLS Shaft construction is shown in Figure 4-23.
RLS/FLOW SPLITTER SHAFT CONSTRUCTION STAGING AREA - PLAN
Slurry Wall Construction
Approx. 2.5 ac (including entrance area)
LEGEND
Slurry Separation Plant Generator
Compressor
Cage Fabrication/Storage
Area
Storage Boxes
Excavated Material Storage (3 Days)
Entry/Exit gate
Crane
Stabilized Construction Entrance
Vehicle Type: WB-50
Optional excavated material storage area for re-use
Front of Plant Stabilization and Staging Areas During
Shaft Construction (By Others)
Constructed in Parallel with RLS Shaft (By Others)
Temporary Construction Wall (By Others)
Radio R
d
Radio Rd
C PROPOSED 15' OD
DIA. TUNNEL
L
Trailer City
Area for
SITE
CIVIL
32' INSIDE DIA.
FLOW SPLITTER
SHAFT
52' INSIDE DIA.
RLS SHAFT
Kennedy/Jenks Consultants
SILICON VALLEY CLEAN WATER
TUNNEL PROJECT - TM No. 4
RLS/FLOW SPLITTER SHAFT
CONSTRUCTION - SITE STAGING PLAN
Radio
Road
2
1
3
4
5
6
7
8
10
9
11
12
13
14
12
11
13
9
7
10
6
5
4
1
8
23
STAGING AREA
LIMITS
14
1"=100'
0 100 200
K/J 1568063.02
JUNE 2016 FIGURE 4-23
Kennedy/Jenks Consultants
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Planning Level Technical Memorandum No. 4
Shaft Construction
This plan reflects slurry wall construction and a Figure “8” configuration. As noted previously, two
construction methods (slurry wall and caisson) and two configurations (Figure “8” and two
separate shafts) are recommended for further evaluation during preliminary design. It is
anticipated that the overall staging area shown in Figure 4-23 can accommodate both methods and
configurations. Major construction equipment and laydown areas are identified in the staging plan
including: a designated area for slurry separation plant, generator, compressor, and cage
fabrication/storage area. As shown in Figure 4-23, all vehicles can access the site from Radio Road
at the stabilized construction entrance and gate on the north side of the site. Adequate space would
be available for larger vehicles to make U-turns in the middle of the site and exit through the same
gate.
The main considerations for establishing the requirements for the TBM removal staging area from
the Flow Splitter Shaft include: FOP construction which will be occurring adjacent to the site and in
parallel with the TBM removal, sufficient working area for the crane retrieving the TBM
andsufficient area for loading the TBM pieces onto the transport vehicle. The staging plan during
TBM Retrieval from the Flow Splitter Shaft is shown in Figure 4-23A.
Kennedy/Jenks Consultants
SILICON VALLEY CLEAN WATER
TUNNEL PROJECT - TM No. 4
Radio R
d
Radio Rd
LEGEND
1 ENTRY/EXIT GATE
2 COMPRESSOR
3 GENERATOR
4 EXIT FROM THE SITE THROUGH FRONT OF PLANT
PAVED ACCESS ROAD
5 TEMPORARY CONSTRUCTION WALL (BY OTHERS)
6 VEHICLE TYPE: WB-50
6
AREA FOR
SHAFT
CONSTRUCTION
STAGING
AREA FOR
RLS
CONSTRUCTION
STAGING
Work
Area
FLOW SPLITTER SHAFT (TBM RETRIEVAL) STAGING AREA - PLAN
Approx. 0.4 ac
L PROPOSED
15' DIA. OD TUNNEL
C
1
AREA FOR
HEADWORKS
CONSTRUCTION
STAGING
32' INSIDE DIA.
FLOW SPLITTER
SHAFT
5
2
3
RADIO ROAD
K/J 1568063.02 JUNE 2016
FIGURE 4-23A
1
4
STAGING AREA
1"=100'
0 100 200
FLOW SPLITTER SHAFT (TBM RETRIEVAL) SITE STAGING PLAN
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Planning Level Technical Memorandum No. 4
Shaft Construction
The WB-50 design vehicle type selected for both site layouts at this location has similar wheel base
and overall dimensions to a standard lowboy tractor trailer combination vehicle anticipated for in
use in delivery of construction material and equipment to the site during shaft construction. It is
anticipated a standard lowboy tractor trailer combination transport vehicle would also be used for
transporting the TBM from the site.
4.1.4.4 Utility Requirements Utility requirements for this site will include temporary power during shaft construction and TBM
removal. Further coordination with SVCW is required to determine if the shaft construction power
will be supplied as part of the overall FOP improvements. Anticipated electrical requirements for
shaft construction and TBM removal include 480V, 3 phase, 4-wire electrical line power with
generator facilities for back-up power.
Additional utility requirements include potable water and sewer service facilities for the onsite
construction trailer facilities (likely constructed by others). Existing potable water and sewer
facilities are located along Radio Road adjacent to the project site. It is anticipated that service
connections into these facilities will be utilized for construction facilities associated with shaft
construction as well as FOP improvements. Site drainage facilities will also be provided as part of
FOP improvements.
4.1.4.5 Long Term Operations and Maintenance Facility Requirements Long term operation and maintenance (O&M) requirements of the flow diversion facilities which
would be installed in the Flow Splitter Shaft and the RLS Shafts are anticipated to be developed by
others.
4.1.5 Construction Considerations
4.1.5.1 Mobilization Two separate mobilization periods are anticipated to occur at this site. An initial mobilization
period would occur for shaft construction and a subsequent mobilization period would occur for
TBM removal from the Flow Splitter Shaft. Initial mobilization for shaft construction would occur
after the site is stabilized and construction screening wall is constructed (by others). Initial
mobilization at this location would include transportation of contractor's personnel, equipment,
and operating supplies to the site required for shaft construction. Mobilization for shaft
construction would also include installation of contractor’s field offices, site fencing, gates, utilities
and other necessary general facilities for the contractor's operations at the site. The initial
mobilization period will also consist of the contractor obtaining all the required insurance, bonds
and permits specific to working at this location such as addressing dirt hauling concerns working
with Redwood City. Mobilization for TBM removal from the Flow Splitter shaft would include
transportation of equipment and materials required to remove the TMB from the shaft. For more
details of the staging area, refer to the "Staging Area Requirements" section above.
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Planning Level Technical Memorandum No. 4
Shaft Construction
4.1.5.2 Excavated Material Handling Soil from shaft excavation would either be temporarily stock-piled onsite for off-site hauling and
disposal at a suitable disposal site in accordance with applicable federal, state and local regulations,
or dried and treated (if necessary) for use as fill for other FOP construction. An area for temporary
stockpiling of shaft excavation material to be re-used, adjacent to and outside of the RLS/Flow
Splitter Shaft staging area, has been identified in the FOP preliminary staging layouts. This area is
shown on Figure 4-23. The potential for re-use and associated re-use quantities will be
determined during design and coordinated with FOP activities.
For the purpose of this TM and for the purpose of establishing areas for temporary soil stockpiling
onsite, it has been assumed all of the excavated soil would be temporarily stockpiled onsite and
hauled away for offsite disposal. Excavated material that cannot be hauled away during the hauling
hours each day would be stored onsite for hauling on the following work day. Approximately three
(3) days of excavated material can be accommodated onsite based on the preliminary site staging
layout, utilizing a shaft excavation rate of 4 vertical linear foot per day (VLF/day) and average 5-
foot high stockpiles.
The excavated material would need to be sampled and analyzed to characterize the soil and
determine if there is any soil contamination. Soil characterization is necessary to confirm the
disposal classification for off haul, prior to offsite disposal or re-use. Acceptance of the soil at a
landfill will depend upon overall disposal quantity and soil characterization and or contamination.
Non-contaminated and contaminated material would be subjected to the profiling requirements of
the disposal facility. Ox Mountain Sanitary Landfill, located in Half Moon Bay, is the closest landfill
that accepts this type of construction excavated material. Habitat restoration fill is another off-site
disposal option. Ultimately, the Contractor will identify the excavated material disposal location(s)
unless SVCW either uses the material on-site or makes arrangements for use in habitat restoration.
Hauling of excavated material from this site will require dirt hauling on the City of Redwood City
streets. Hauling within Redwood City is generally not allowed on weekends or holidays. Hauling is
also generally not allowed before 7:30 am or after 4:00 pm. SVCW has intergovernmental
immunity for local agency permits, however SVCW cooperates with local agencies to minimize
impacts on residents. Due to the close proximity of location to residential areas along Redwood
Shores Parkway and Sand Piper Elementary, additional hauling hour restrictions maybe
appropriate. Hauling could potentially be limited to the hours of 8 am and 1 pm from this site due
to elementary location along the haul route and elementary school hours of 8 am to 2 pm.
A preliminary analysis of the anticipated excavated material handling for this site and anticipated
excavated material quantities for this site is provided below.
Excavated Soil: Approximately 11,120 cubic yard (CY)
Hauling Trucks: 3 average commercial 12.5 loose cubic yard (LCY) dump trucks
Hauling Duration: 27 weeks
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Planning Level Technical Memorandum No. 4
Shaft Construction
Potential ultimate disposal site: Ox Mountain Sanitary Landfill or wetland restoration area
Average round-trip haul distance: 28 miles
4.1.5.3 Water Handling, Treatment and Disposal Although an impervious system for the RLS/Flow Splitter Shaft construction will be utilized to
minimize water inflow into the excavation due to the artesian conditions at this site, it is anticipated
some level of water handling and disposal will be required. The anticipated water handling
quantities for this location during shaft construction will be established based on the selected
impervious system and groundwater information which will be included in geotechnical baseline
report for this Gravity Pipeline and utilized for sizing the water handling facilities.
Construction related water, including contaminated groundwater, would be collected and
temporarily stored in baker tank(s) and pumped to the WWTP Plant Storm Water System which is
diverted to the WWTP for treatment, as required by Regional Water Quality Control Board
(RWQCB) regulations. Since this shaft location falls within the boundaries of the drainage footprint
of the WWTP, storm water (which would be diverted away from the shaft excavation) would also
be collected from the shaft staging site during shaft construction and ultimately routed to the
WWTP Plant Storm Water System for treatment.
Water handling facilities at this site are anticipated to include sump pump(s) during shaft
excavation for pumping groundwater inflow from the excavation to the surface, baker tank(s) for
collection of contaminated groundwater and additional pumping equipment to pump/divert water
to the Plant Storm Water System. The Contractor will be responsible for meeting the requirements
of the “REGULATIONS of Silicon Valley Clean Water” (Amended 2005), specifically ARTICLE II,
PROHIBITIONS, in its entirety (Refer to Appendix B) and SVCW Standard Specification Section
01060. Both of the above referenced requirements summarize the specific wastes and discharges
prohibited from entering the sewerage facilities.
Further coordination with SVCW is required during preliminary design to establish potential
allowable discharge flow rates into the WWTP to avoid overloading of the sewerage facilities.
4.1.5.4 Shaft Site Restoration and Permanent Facilities The RLS/Flow Splitter Shaft finish-out including flow channelizing facilities which will be located
within the shaft utilized for TBM removal, lift station facilities and site restoration will be designed
by others as part of the FOP improvements. Preliminary layouts prepared by others indicated the
site restoration will include raising the site elevation and site grading, a permanent frontage wall,
landscaping and trees along the western perimeter of the site, along Radio Road. Other site civil
improvements include, but are not limited to, storm drainage improvements to prevent flooding,
driveway and roadway improvements to create a safe vehicle routing and asphalt concrete (AC)
pavement to provide a drivable, weather proof surface to access and serve the new facilities. The
area around the permanent RLS facilities will receive AC pavement.
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Planning Level Technical Memorandum No. 4
Shaft Construction
4.1.5.5 Geotechnical Instrumentation and Monitoring During the shaft excavation operation, it is essential to maintain soil materials and groundwater
conditions outside of the excavation as close to pre-excavation conditions as reasonably possible.
Changes (disturbances) to the in situ conditions surrounding the excavation (soil loss,
lateral/vertical soil movement, drop of groundwater, etc.) could result in detrimental settlement of
structures or utilities supported by the "disturbed" soils. As a result, the initial support system used
during shaft excavation are designed to maintain the in situ pre-excavation conditions by
supporting the soil and keeping the groundwater table at a normal level as possible.
Existing structures, pavements and underground utilities within the influence zone of the shaft
excavation would be monitored during the shaft excavation work. Typically, 150 to 200 feet radius
from the center of the shaft is considered for the influence zone. Further evaluation of the influence
zone will be performed taking into consideration the selected initial support method. In a manner
similar to monitoring performed during tunnel operations, the shaft monitoring will provide timely
warning before excavation related settlement can affect adjacent structures, pavements and
underground utilities. If the recorded movements reach action levels, the Contractor will stop his
operations and modify his shaft excavation methods and procedures to eliminate the unacceptable
ground movements.
Regular periodic recording of instrument readings and data review/evaluation will be specified to
assess ground behavior near shaft excavation.
The proposed location of the RLS Shaft will be in an open field adjacent to Radio Road; this areawill
be paved as part of the completion of construction in the Front-of-Plant area. There are existing
underground utilities, including an 18-inch force main in vicinity of the shaft. There are no existing
structures within the influence zone. Therefore, the monitoring program proposed for the RLS Shaft
excavation would include instruments to measure vertical and lateral ground movements,
settlement of utilities and pavement, and groundwater fluctuations outside of the shaft excavation.
Specifically, the type of instruments required for the Gravity Pipeline will include:
Settlement Indicator Points to measure pavement and utility settlements.
Subsurface Shallow Settlement Indicators to measure settlement of ground near surface.
Inclinometers installed adjacent to the initial shaft supports to measure lateral earth
movements as the shaft excavation progresses.
Control groundwater observation wells installed adjacent to the shaft excavation to
measure groundwater levels.
Prior to commencement of work, a pre-construction survey will be implemented to document the
existing conditions of all pavement structures located entirely or partially within the shaft
excavation influence zone. The pre-construction survey will document condition of pavement
structure to provide baseline data for evaluating construction claims.
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Planning Level Technical Memorandum No. 4
Shaft Construction
4.1.6 Recommendations The following criteria were considered in the evaluation of the RLS structure construction methods:
shaft use
size/shape/depth
constructability
soil condition
groundwater levels
shaft construction cost
schedule
A comparison table of the three (3) evaluated initial support methods is presented below.
Table 4-10: RLS Initial Support Methods Comparison
Slurry Wall Secant Piles Caisson
Method well known and utilized in the United States. Competitive bidding expected.
Method well known and utilized in the United States. Competitive bidding expected.
Not common method in the majority of the United States. Further evaluation is recommended.
Median shaft construction duration.
Shortest shaft construction duration. However, additional layer of shotcrete may be necessary to provide required smoothness of the shaft surface for corrosion protection installation, which would affect the duration.
Longest shaft construction duration.
Slurry Wall Secant Piles Caisson
The cost of these methods will depend on the water-sealing element at the shaft bottom. For the comparison cost of the initial support systems refer to Tables 4-8 and 4-9.
Reinforcement can be provided to carry unbalanced lateral pressures.
Sensitive to unbalanced lateral pressures. Additional layer of structural lining may be required.
Reinforcement can be provided to carry unbalanced lateral pressures. Reinforcement can be continuous in both directions.
Relatively smooth walls achievable.
Irregular surface. Provides uniform interior surface of structure.
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Planning Level Technical Memorandum No. 4
Shaft Construction
From all three (3) initial support methods evaluated, the slurry walls and caisson are the
recommended options for further evaluation. The secant piles are not recommended since the
system would be reaching its practical limits of installation and would produce the most amount of
infiltration from the three systems evaluated. During the preliminary design, an actual initial
support system will be recommended once the structure configuration is selected.
Two configurations for the RLS Shaft construction are envisioned at this time: figure "8" and two
separate shafts with a connection tunnel near the bottom. These two configurations will be further
evaluated by the PDB.
4.2 Airport Access Shaft
4.2.1 Site Geology The information about general subsurface conditions at the Airport Access Shaft is based on the
Phase I subsurface exploration program performed by Geotechnical Consultants Inc., and its
findings are presented in the "Preliminary Characterization of Subsurface Conditions" Technical
Memorandum dated December 9, 2015.
The existing subsurface conditions at the Airport Access Shaft were developed from two borings at
the proposed shaft location (B-106 and B-110) in addition to in situ field test results performed on
selected soil samples. The maximum boring depth obtained was 84.5 feet below the ground surface.
Following the corrosion protection layer installation, all three initial support methods will offer the same shaft finish.
Some leakage may occur through joints. Grouting of leaks may be required prior placing of the corrosion protection layer.
The most amount of leakage is anticipated due to large number of joints. Additional layer of shotcrete is recommended to enhance the long term impermeability of the system. Grouting of leaks may be also required prior to placing of the corrosion protection layer.
The least amount of leakage is anticipated due to the presence of gaskets or water stops at the joints. Grouting of leaks may be required prior placing of the corrosion protection layer.
Achievable depth of slurry wall can be up to 200 ft. RLS walls are well within the practical range of the system.
Achievable depth of secant piles is approximately 80 ft. Not recommended for extending the system to the Old Bay Deposits for water cut-off as the system would reach approximately 100 feet.
No depth limits.
This method is recommended for further evaluation.
This method is not recommended for further evaluation since the system would be reaching its practical limits of installation and would produce the most amount of infiltration.
This method is recommended for further evaluation.
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Planning Level Technical Memorandum No. 4
Shaft Construction
No piezometers were installed at these boring locations and no laboratory tests were performed on
soil samples obtained at this shaft location.
Artificial Fill covers the site to a depth of 5 to 8 feet below the ground surface and consists of clay
and silt with varying amounts of sand/gravel. Varying quantities of organic materials, cobbles and
debris were encountered within the fill. Young Bay Mud underlies the fill with a layer thickness
between 10 and 12 feet. The Young Bay Mud consists of very soft to soft, highly compressible and
plastic, near normally consolidated fat clay. Zones of trace to abundant shell fragments, organic
materials and occasional thin layers of peat (less than a few feet in thickness) are contained within
this layer. Standard Penetration Test (SPT) results ranged from WOR to 4 blows/foot. Pocket
penetrometer field readings indicate an apparent undrained compressive strength of 1,200 psf.
Below the Young Bay Mud, Upper Layered Sediments are encountered with a layer thickness
between 39 and 40 feet. These soil deposits consist of complex alternating layers of lean clay, silty
clay and sandy clay. The thickness, sequencing and consistency of these individual layers are highly
variable. SPT results ranged from 4 to 36 blows/foot. The fine grained materials (silts and clays)
have a generally stiff to very stiff consistency. Pocket penetrometer field readings indicate an
apparent undrained compressive strength ranging from 1,000 to over 5,200 psf.
Old Bay Deposits underlie the Upper Layered Sediments and extend to at least the bottom of the
deepest boring performed at this shaft site, a depth of 84.5 feet below the ground surface. This layer
of marine sediments consists of stiff to hard fat clay and lean to sandy clay with occasional
scattered shell fragments. SPT results ranged from 12 to 50 blows/foot. Pocket penetrometer
readings indicate an apparent undrained compressive strength ranging from 2,000 to 8,000 psf.
Groundwater was not encountered in either of the two borings since the materials penetrated
consist predominantly of fine grained soil materials (silts and clays).
4.2.2 Shaft Excavation 4.2.2.1 Excavation Size and Configuration The Airport Access Shaft would serve as a temporary structure intended to provide enough work
area for the proposed Gravity Pipeline construction. It will serve as the launch location for the TBM.
Selecting the necessary size of this shaft is directly related to the tunnel size, construction activities
within the shaft and the Gravity Pipeline schedule. Based on the latter criteria, it has been
determined that the Airport Access Shaft would be circular, approximately 52 feet deep and 35 feet
in diameter. The criteria for the shaft size selection are as follows:
The maximum excavated tunnel diameter is 15 feet.
Construction activities related to the excavation of the two proposed tunnels (one to WWTP
and another to Inner Bair Island) will be conducted in sequence.
The pipe installation will follow the tunnel completion.
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Planning Level Technical Memorandum No. 4
Shaft Construction
A circular shape was selected since it is the most efficient shape for shaft construction. Under
lateral pressures, the predominant force that develops is compression, well resisted by concrete.
Typically, circular shafts provide a stiff continuous support that does not require internal bracing or
toe embedment for shaft wall stability.
It is anticipated that after completion of the gravity sewer, an access structure to the sewer system
will be installed at the shaft location. The details of the structure are covered in Technical
Memorandum No. 5 (TM 5).
4.2.2.2 Excavation Methods Conventional soil excavation techniques such as a crane and a clamshell bucket or an excavator can
be utilized to excavate the materials within the shafts. The excavated muck would be hoisted to the
surface by a crane directly in the clamshell or lifting buckets.
4.2.3 Initial Support 4.2.3.1 Support Methods and Evaluation From five shaft initial support methods selected for the Gravity Pipeline in Section 4 of this
memorandum, four are considered for the Airport Access Shaft construction, namely: slurry walls,
secant piles, CSM and sheet piling. The caisson method was excluded as it is more suitable for
permanent type structures.
A conceptual design was performed for each of the selected support systems to determine the
structural behavior of the systems under estimated loads. The following geological conditions have
been considered in the evaluation of support of shaft excavation: the first 8 feet of the shaft would
be constructed in very soft Artificial Fill, followed by 12 feet of very soft to soft Young Bay Mud,
then 32 feet of stiff to very stiff Upper Layered Sediments.
Slurry walls
Based on the conceptual design, it is anticipated that a minimum 2.5 feet thick reinforced slurry
wall would be required for the Airport Access Shaft (refer to Figure 4-24). A circular shaft
constructed from reinforced concrete slurry wall panels would provide a very rigid initial support,
which would minimize soil movement and settlements during shaft excavation.
The slurry wall would extend to a level of few feet below the invert. The excavation could then
proceed down to the required target depth. A mud slab would be installed at the shaft invert to
provide smooth and firm working surface for tunneling activities taking place in the shaft. In lieu of
steel reinforcement, fiberglass bars will be used at the eye of the tunnel in the slurry wall panels to
allow for TBM penetration. An additional cast in place reinforced concrete wall may be required at
the tunnel eye to resist the breakout forces.
The excavation for the slurry walls can be performed with equipment requiring low overhead
constraint of 21 feet and less; however, the height of the reinforcing cages in one unit (where the
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Planning Level Technical Memorandum No. 4
Shaft Construction
reinforcing cages would be preassembled and dropped into the wall in one piece) would be about
55 feet and thus require equipment with an overhead clearance of approximately 80 feet. For the
low overhead clearance requirement, the reinforcing cages can be spliced and installed in several
lifts. This method would increase the cost and duration of installation of the slurry walls. The cost of
the slurry wall system is the most expensive compared to other systems.
Figure 4-24: Slurry Wall Alternative
Secant piles
It has been determined that approximately 3.5 feet diameter unreinforced piles would be required
for the Airport Access Shaft to efficiently resist the circumferential compression in concrete and
accommodate the vertical pile construction deviations (refer to Figure 4-25). The piles would be
unreinforced except for the piles at breakouts, which would have steel shapes or a reinforcing cage
within them. The reinforcing within the pile would not extend for the whole depth of the shaft, but
be localized around the breakout opening. Similarly, to slurry walls, the secant pile wall would
provide very rigid initial support minimizing soil movements and settlements during shaft
excavation.
A mud slab would be installed at the shaft invert to provide smooth and firm working surface for
the tunneling activities taking place in the shaft. Two cast-in-place reinforced concrete breakout
walls would be constructed and connected to the secant pile wall to resist the TBM breakout forces.
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Planning Level Technical Memorandum No. 4
Shaft Construction
The secant pile system is commonly used and can be installed with low overhead clearance
requirements of 21 feet and less. It is a relatively low cost option for the construction of the Airport
Access Shaft.
Figure 4-25: Secant Pile Alternative
Cutter soil mixing (CSM)
Two options are envisioned for the CSM system. The first would comprise of a thick wall of CSM
layer with no additional internal support within the wall. The second option would be a
combination of CSM and a layer of shotcrete reinforced with welded wire fabric. For both systems,
the CSM wall would be installed down a few feet below the tunnel invert to anchor the wall and
prevent invert instability.
For the CSM wall alone (Option 1), it is anticipated that a 5-foot thick unreinforced CSM wall would
be required for the Airport Access Shaft to efficiently resist the circumferential compression. The
construction would entail two rings with a combined total thickness of 5 feet (refer to Figure 4-
26).
The second system (Option 2) can be achieved by constructing a double wall system. First, an
approximately 3 foot thick CSM wall ring would be installed followed by an inner layer of reinforced
shotcrete sprayed on the wall of the shaft as the excavation progresses. The overall system results
in a thinner wall (refer to Figure 4-27).
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Planning Level Technical Memorandum No. 4
Shaft Construction
The CSM wall would provide a rigid initial support limiting soil movements and settlements. A mud
slab would be installed at the shaft invert to provide smooth and firm working surface for the
tunneling activities taking place in the shaft. Two cast-in-place reinforced concrete breakout walls
would be constructed to resist TBM breakout forces.
The CSM is a commonly used construction method and can be installed with low headroom
requirements of 21 feet and less. However, the equipment available and commonly used in the
United States is approximately 60 foot in height and above. The CSM low overhead equipment had
been used on several overseas projects. Procuring this equipment for this Gravity Pipeline is
optional, however, it could have a negative effect on the shaft construction schedule and cost. In
addition, the CSM shaft construction method it is best suited for granular soils where adequate
strength of the final system is achievable. In the case of the tAirport Access Shaft, where the soils
are mainly clays, the strength of the CSM is less predictable and reliable.
Figure 4-26: Double CSM Ring Alternative – Option 1
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Planning Level Technical Memorandum No. 4
Shaft Construction
Figure 4-27: CSM Ring with Reinforced Shotcrete Alternative – Option 2
Sheet piles
It is anticipated that a sheet pile wall with circular rings consisting of wide flange shape ribs or
reinforced concrete beams would be required for the Airport Access Shaft to efficiently resist the
anticipated loads at the shaft site (refer to Figure 4-28). This method of initial support would
require driving steel sheet piles approximately 12 to 15 feet below the shaft invert to provide
sufficient embedment for the system stability. The bracing of the sheet piles would be installed as
the excavation progresses. The sheet piles would be the most flexible shaft initial support method
from all proposed for the Airport Access Shaft construction and would have the larger shaft
excavation influence zone where monitoring would be required.
At the two breakout locations, steel reinforcing members would be installed around the opening to
allow for the sheet piling to be cut or pulled up. To provide stability at the launch eye when the
sheet piling is cut, jet grouting would need to be performed to create a stable soil mass in front of
each TBM breakout location. Two cast-in-place reinforced concrete breakout walls would be
constructed to install a breakout seal.
Over 60 feet of headroom would be required at the Airport Access Shaft to install the sheet piling in
one piece. For low headroom requirements, sheet piles can be spliced and installed in sections. This
would increase the cost and the duration of construction. Sheet pile driving produces a higher level
of noise and vibrations than the other options presented in this memorandum.
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Planning Level Technical Memorandum No. 4
Shaft Construction
Figure 4-28: Sheet Piling Alternative
Groundwater Control at Airport Access Shaft
Based on the results of the geotechnical sampling program, no special groundwater control
mitigation at the bottom of the shaft is anticipated at the Airport Access Shaft. The shaft would be
constructed entirely in fine-grained silts and clays generally characterized by low permeability.
However, an impermeable excavation support is recommended since the shaft would be located in
the vicinity of a nearby open water channel (Phelps Slough) and Steinberger Slough. Even with an
impermeable support system, a small amount of water can be expected at the bottom of the shaft
due to infiltration; the water would be pumped out as it accumulates.
Impermeable systems comparison cost
Relative comparison costs for the Airport Access Shaft impermeable system options are shown in
Table 4-11. The costs were developed in 2015 prices. Mark-ups of 25 percent for indirect costs and
15 percent for overhead and profit are included in the costs. The costs do not include contingency
and escalation. Refer to Appendix A.
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Shaft Construction
Table 4-11: Airport Access Shaft Initial Support Cost Comparison
Initial Support Method Initial Support Cost (Millions)
Slurry Walls $2.9
Secant Piles $2.6
CSM $2.7
Sheet Piling $2.4
4.2.4 Site Conditions The Airport Access Shaft site is located north of the Shoreway Road and Redwood Shores Parkway
(Holly Street) intersection, in Redwood City. This site will serve as the TBM launching location and
primary staging area for tunnel construction as well as staging area for the San Carlos Drop Shaft,
which has limited construction area.
4.2.4.1 Site Ingress and Egress Access to the Airport Access Shaft site would be provided from Shoreway Road. The site location
and ingress and egress to/from the site from Highway 101 and surrounding areas is shown in
Figure 4-29, below.
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Figure 4-29: Airport Access Shaft Site Ingress and Egress
Specific ingress/egress gate location and access requirements within the site for construction
vehicles is considered in the site staging requirements for the site and is discussed in further detail
in Section 4.2.4.3.
4.2.4.2 Existing Site Conditions The existing ground surface at the Airport Access Shaft staging area is mostly undeveloped dirt with
dense tree and bush coverage along the property boundary, particularly on the eastern side of the
site. There is a swale (approximately 1-2 ft deep) parallel to Shoreway Road near the eastern edge
of the site. There is a 14-inch drainage culvert across the proposed site entrance. The site is gently
undulating with a ridge along the site from north to south and generally slopes east and west from
the ridge along the Airport Access Shaft of the site. An open drainage channel borders the western
edge of the site.
WRA Environmental Consultants recently performed jurisdictional wetland delineation of the
proposed shaft site area and the northern, western and eastern areas surrounding the site. The
purpose of the delineation was to determine the presence and extent of wetlands and waters
potentially subject to jurisdiction by the U.S Army Corps of Engineers (ACE), Regional Water Quality
Shaft Construction Site
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Control Board (RWQCB) or California Department of Fish and Wildlife (CDFW). The study area
encompassed approximately 18.96 acres. The draft delineation map of the area (provided in
Appendix C) identifies wetland areas on the northern, western and eastern boundaries of the
proposed staging area. In addition, a small area (approximately 0.06 acres) of jurisdictional waters
was identified within the drainage easement bordering the northeast site boundary.
There are existing overhead power lines and power poles located across the extents of the site from
northwest to southeast. Based upon communication with Beecher Engineering staff (working on
PG&E permit for this location), the overhead power wires include primary conductors with nominal
voltage up to 12 kilovolts (kV).
A 66-inch reinforced concrete pipe (RCP) storm drain is located beyond the southeast side of the
site draining to a natural drainage channel along the east side. This storm drain is connected to a
culvert with a headwall located at the edge of the sidewalk. This culvert drains water collected from
the Phelps Slough located on the east side of Redwood Shores Parkway. Another 66-inch RCP
storm drain is located near the northern border of the site. This storm drain collects water from
the open drainage channel and storm drain facilities along Twin Dolphin Road. In addition to
power and drainage facilities, various communication facilities exists outside of the staging limits in
the sidewalk within public right-of way along Redwood Shores Parkway.
4.2.4.3 Staging Area Requirements The Airport Access Shaft site staging area is planned to accommodate staging for construction
activities associated with the 42-foot OD (35-foot ID) TBM Airport Access Shaft launch shaft, 15-
foot OD tunnel and carrier pipe and the 15 to 20-foot outside diameter shaft at San Carlos. The
TBM launch shaft will be constructed first, prior to tunnel construction. The San Carlos Drop Shaft
will is expected to be constructed concurrently with the tunnel. It is conservative to plan the
staging area assuming the Gravity Pipeline and the San Carlos Drop Shaft will be constructed at the
same time.
Prior to construction, the staging area would be cleared of trees, vegetation, and groundcover. The
staging area perimeter would be fenced with a 6-foot high security fence to prevent unauthorized
access and enhance the safety of the public. A surface layer of base rock or gravel would be installed
to provide a working surface for construction activities and a stabilized construction entrance
would be installed at the site entrance/exit to reduce the tracking of construction mud and dirt
onto public roads by construction vehicles.
The staging area would accommodate construction trailers, locker room(s), 2-week muck storage,
2-week ring segment/pipe storage, storage box, fuel storage area, grout material storage area,
topman house (tunnel staff enclosure/shelter), electric substation, air supplies, warehouse, first aid
station, polymer storage area for grout additives used in stabilizing soil ahead of tunnel excavation,
and parking area in front of the trailers. The required area for excavated material storage is
discussed in Section 4.2.5.2. The site staging area plan is shown in Figure 4-30.
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SILICON VALLEY CLEAN WATER
TUNNEL PROJECT - TM No. 4
K/J 1568063.02
February 2017
OPEN CHANNEL EASEMENT
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LEGEND
OWNER/CM TRAILER
CONTRACTOR TRAILERS
LOCKER ROOM
JOB PARKING
MIDDLE OUT/SAN CARLOS SHAFT -
2 WEEKS MUCK STORAGE (486'X112.5')
2 WEEKS SEGMENT/PIPE STORAGE (487'X69')
ENTRY/EXIT GATE
STORAGE BOXES
FUEL STORAGE
GROUT MATERIAL STORAGE
TOP MAN HOUSE
SAN CARLOS
STAGING AREA
AIRPORT ACCESS SHAFT STAGING AREA - PLAN
Approx. 6.3 ac
ANTICIPATED CRANE
LOCATION ZONE
AIRPORT ACCESS SHAFT - SITE STAGING PLAN
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1"=100'
0 100 200
FIGURE 4-30
POWER POLE SAFETY
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FAA AIRSPACE PROTECTION NOTES:
1. AIRSPACE PROTECTION SURFACE ELEVATIONS ON THIS EXHIBIT ARE EXPRESSED IN FEET
ABOVE MEAN SEA LEVEL (MSL). THE ELEVATION OF SAN CARLOS AIRPORT IS 5 FEET MSL.
2. LOCATIONS WHERE THE GROUND/TERRAIN PENETRATES THE FAR PART 77 AIRSPACE
SURFACES ARE APPROXIMATE AND WERE DEVELOPED USING ALUCP EXHIBIT 4-4 WHICH
UTILIZED GROUND ELEVATION CONTOURS PROVIDED BY THE SAN MATEO COUNTY
PLANNING AND BUILDING DEPARTMENT 2014.
3. SOURCE: SAN CARLOS AIRPORT ALUCP, EXHIBIT 4-4 (ESRI, 2014; SAN MATEO COUNTY
PLANNING AND BUILDING DEPARTMENT, 2014; ESA AIRPORTS, 2014).
35' INSIDE DIA. AIRPORT
ACCESS SHAFT
L
FAA AIRSPACE PROTECTION
SURFACES (SEE NOTES)
ELECTRIC SUBSTATION
AIR SUPPLIES/COMPRESSOR
WAREHOUSE
FIRST AID
SECURITY SHACK
POLYMERS STORAGE
WATER TREATMENT FACILITIES
RESTROOM FACILITIES
INGRESS/EGRESS ROUTE TO HWY 101
STABILIZED CONSTRUCTION ENTRANCE
VEHICLE TYPE: WB-50
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WETLANDS
WETLANDS
WETLANDS
SURVEYED PERMIT
AGREEMENT
BOUNDARY
TEMPORARY
POWER DROP
AND METER
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Approximately 6.4 acres of staging area within airport property (airport permitted area) is planned
for the Airport Access Shaft site location. An additional area of approximately 0.1 acres of
construction area is anticipated within public right-of-way due to the proximity of the Airport
Access Shaft to the adjacent right-of-way. Pedestrian protection along the sidewalk on Redwood
Shores Parkway, near the shaft, may be required.
The following have been considered in developing the staging area requirements:
Tunnel Excavation Rate: Approximately 100 feet per day
Design Vehicle Type: WB-50 (semi- trailer combination)
Shaft Location relative to overall staging area
Location of adjacent wetland boundaries
Additional storage area for San Carlos Drop Shaft construction
Site access from public right-of-way
The WB-50 design vehicle type selected for this site has similar wheel base dimensions to standard
lowboy tractor trailer combinations anticipated for in use in delivery pipe and other construction
material and equipment to the site.
It should be noted that additional survey and staging area refinement will be needed during design
to confirm that the area permitted by the San Carlos Airport will not include any wetland, drainage
easement or street right of way areas.
4.2.4.4 San Carlos Airport and Federal Aviation Administration Considerations The Airport Access Shaft staging area is located within the San Carlos Airport (SCA) Inner
Approach/Departure Zone. In addition, the staging area for this site also encroaches into the
Runway Protection Zone. Refer to TM No. 1, Appendix A (Exhibit 4-3) for SCA safety zones.
Airspace protection surfaces are imaginary surfaces in the airspace surrounding airports defined in
accordance with criteria set forth in 14 Code of Federal Regulations, Part 77, Subpart C. Except as
noted below in items 1-3, no structure or object, including a temporary object such as a
construction crane, shall have a height that would result in penetration of any of the airspace
protection surfaces. Any object that penetrates one of these surfaces is, by Federal Aviation
Administration (FAA) definition, an obstruction. A proposed structure or object having a height
that exceeds the airspace protection surfaces for San Carlos Airport is compatible with the airspace
protection goals if all of the following apply:
1. As the result of an aeronautical study, the FAA determines the object would not be a hazard
to air navigation; and
2. FAA or the airport operator concludes that, despite being an airspace obstruction (not
necessarily a hazard), the object would not cause any of the following:
An increase in the ceiling or visibility minimums at San Carlos Airport for an existing or
planned instrument procedure;
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A diminution of the established operational efficiency of the airport, such as by causing
the usable length of the runway to be reduced;
Conflict with the visual flight rules (VFR) airspace used for the airport traffic pattern or
en route navigation to and from San Carlos Airport.
3. Marking or lighting of the structure/object is installed as directed by the FAA aeronautical
study or the Division of Aeronautics and in a manner consistent with FAA standards in
effect at the time the construction is proposed.
FAA Airspace protection surfaces across the site staging area are shown Figure 4-30. The staging
area is primarily located within 55-foot to 105-foot airspace protection elevation contours. It
should be noted these contour elevations represent an elevation in feet above mean sea level.
Based upon the location of these contours across the staging area, the estimated protection surface
elevation above the existing site grade elevation near the shaft construction area is estimated to be
62–81 feet above grade. Refer to Table 4-12 for additional information. The crane used for
construction of the shaft and lowering the TBM into the shaft is anticipated to be up to
approximately 80 feet in height, encroaching in the protection surface elevation. However, a
smaller crane could be used for lowering the TBM if it is lowered into the shaft in smaller segments.
The lifting system such as a smaller crane or electric gantry over the shaft for use during tunneling
activities and pipe installation at this location is anticipated to be approximately 50-feet in height.
Table 4-12: Airport Access Shaft Site Airspace Protection Height Restrictions
Notes:
(a) Heights are based upon SCA Part 77 Airspace Protection Surfaces, SCA 2015 ALUCP Exhibit 4-4. Height represents
lowest height within the preliminary anticipated crane working zone.
(b) Based upon preliminary site elevations using Gravity Pipeline vertical datum of NGVD 29 + 100 feet. Grade elevation
relative to MSL was determined by subtracting 100 feet from the preliminary site elevations.
Proposed construction at this location is subject to review and approval by the Federal Aviation
Administration (FAA) (as administered by the SCA) and requires a Federal Aviation Administration
Form 7460-1 be submitted. Specific FAA requirements and conditions associated with the
proposed construction and anticipated crane height encroachment into the in the FAA jurisdictional
areas for the site would be included in the Notice of Determination by the FAA.
4.2.4.5 Utility Requirements The Contractor would be required to provide temporary facilities, including but not limited to,
power, lighting, water, sanitation services, heating and ventilation, communication facilities and
other utilities needed for the construction and the Contractor’s construction trailer at the site. The
nearest fire hydrants to the Airport Access Shaft site are located approximately 400 to 700 feet
Site Height Restriction
(Feet Above MSL)(a)
Grade Elevation (relative to
MSL)(b)
Estimated Height Limit Above Existing Grade
Elevation
Airport Access Shaft 66 – 85 4 62 -81
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north and northeast of the site along Twin Dolphin Drive. There is a waterline located along
Redwood Shores Parkway. Use of this waterline for temporary potable water service during
construction would require tapping into the waterline and constructing temporary facilities across
Redwood Shores Parkway. The nearest sanitary sewer is also located along Twin Dolphin Drive.
The electrical line power requirement for this site is expected to be 4160V electrical line power.
The estimated electrical line power requirement is based on the estimated electrical power
requirements during tunneling of approximately 3,000 kilowatts and ancillary power requirements
for water handling, construction trailers, site lighting. Based upon previous team discussions
regarding temporary power at the Airport Access Shaft location, PG&E has confirmed the required
temporary power for tunnel boring machine (TBM) operations can be provided at this location
from the existing power lines that cross the site.
The existing overhead power lines across the site have been confirmed to be 12kV. The California
Division of Occupational Safety and Health (Cal/OSHA) regulations require minimum safe working
and traveling distances be maintained from cranes to overhead electric lines which are often more
stringent than PG&E clearance requirements.
Tables 1-2 and 1-3 included in PG&E’s Green Book note the minimum Cal/OSHA safe working
distances from 0.6 kV to 50 kV nominal voltage conductors are as follows:
Boom-type lifting or hoisting equipment: 10 feet
Scaffolds, equipment, tools, structures, and people: 6 feet
Based upon review of Cal/OSHA clearance requirements for nominal voltage conductors less than
50kV, anticipated crane operating area, anticipated crane height, and surveyed location of the
onsite power poles and overhead power lines, relocation of the power poles and overhead power
lines is not required to meet clearance requirements.
Relocation of power poles and associated overhead power lines is not anticipated at this site. The
staging area provides sufficient area for the Contractor to work around. Should the Contractor
choose to relocate existing power poles and associated power lines, he/she will be required
responsible for relocation. A temporary service drop and meter would be provided near the
southwest corner of the site, adjacent to the existing power pole. Refer to Figure 4-30.
4.2.4.6 Long Term Operation and Maintenance Requirements The anticipated long-term operation and maintenance requirements at the Airport Access Shaft
location may include infrequent manhole inspections. Should inspection of the tunnel using
advanced technologies (such as sonar) be required after the gravity line is in service, the Airport
Access Shaft site would likely be used for access and inspection due to its central location along the
alignment. Both a bolted on lower flanged cover close to the tunnel and an upper cover at the
surface are recommended to avoid sewer gasses collecting in the access shaft. At a minimum, a
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large corrosion resistance double door hatch (Bilco type) or 48-inch manhole frame and cover
access for lowering equipment and people access are recommended for this shaft site.
4.2.5 Construction Considerations
4.2.5.1 Mobilization Mobilization will include all activities for transportation of contractor's personnel, equipment, and
operating supplies to the Airport Access Shaft staging site necessary for shaft construction. It will
also comprise of the installation of field offices, laboratories, fencing, gates, utilities and other
necessary general facilities for the contractor's operations at the site. For more details on the
Airport Access Shaft staging area, refer to the "Staging Area Requirements" section above. The
mobilization will also consist of obtaining by the contractor all required insurance, bonds and
permits.
4.2.5.2 Excavated Material Handling All excavated material (muck) from Airport Access Shaft construction and overall tunneling
activities for the Gravity Pipeline (approximately 17,600 lineal feet of 15’ OD diameter tunnel)
would be handled at the Airport Access Shaft site location. Excavation of the tunnel includes
removal of the excavated material from the tunnel by use of a conveyor system or muck cars pulled
by a locomotive on rails installed as the tunnel advances. Once the excavated material is brought to
the surface at the Airport Access Shaft location, it would be temporarily stockpiled onsite for
loading and off-site hauling and disposal at a suitable disposal site in accordance with applicable
federal, state and local regulations. In addition, excavated material from the San Carlos Drop Shaft
excavation may be hauled to this location for ultimate off-site hauling and disposal.
Excavated material that cannot be hauled away during the permitted hauling hours each day would
be stored onsite for hauling on the following work day. A staging area for onsite storage of
approximately two (2) weeks of excavated material associated with tunnel production at an
excavation rate of 100 LF is planned for this site based on the preliminary site staging layout and
average 5-foot high stockpiles. Onsite storage for excavated materials stockpiling at this location
would encompass an area of approximately 1.3 acres.
Similar to all excavated material for the Gravity Pipeline, the material would need to be sampled
and analyzed to characterize the soil and determine if there is any soil contamination. Soil
characterization is necessary to confirm the disposal classification for off haul, prior to offsite
disposal or re-use. Acceptance of the soil at a landfill will depend upon overall disposal quantity
and soil characterization and or contamination. Non-contaminated and contaminated material
would be subjected to the profiling requirements of the disposal facility. Ox Mountain Sanitary
Landfill, located in Half Moon Bay, is the closest landfill that accepts this type of construction
excavated material. Ultimately, the Contractor will identify the excavated material disposal
location(s) and/or potential areas for re-use (such as wetland restoration projects).
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Similar to the excavated material from the RLS/Flow Splitter Shaft site, excavated material from
this site will require dirt hauling on the City of Redwood City streets. Based upon the general
Redwood City hauling permit application, hauling within Redwood City is not allowed on weekends
or holidays and hauling is also not allowed before 7:30 am or after 4:00 pm. While SVCW has
intergovernmental immunity and is not required to obtain a permit for dirt hauling, SVCW will
review dirt hauling activities with Redwood City and include appropriate requirements for the
contractor to minimize impacts on the public.
A preliminary analysis of the anticipated excavated material handling for this site and anticipated
excavated material quantities to be handled at this site is provided in Table 4-13 below.
Table 4-13: Summary of Airport Access Shaft Site Excavated Material Handling
4.2.5.3 Water Handling, Treatment and Disposal
Based on the Phase I subsurface exploration program performed by Geotechnical Consultants Inc.,
and its findings presented in the "Preliminary Characterization of Subsurface Conditions" Technical
Memorandum dated December 9, 2015, large quantities of inflow into the shaft excavation during
shaft construction are not anticipated due to the site geology. However, it is anticipated that water
handling and disposal will be required at this site during construction. Additional groundwater
monitoring information for the Gravity Pipeline will continue to be collected as part of the
geotechnical efforts and will be included in geotechnical baseline report for this Gravity Pipeline.
The information will be considered in sizing the water handling facilities during preliminary and
final design.
Groundwater encountered during the construction of the Airport Access Shaft would be pumped
from the excavation to the surface utilizing sump pumps for treatment. Groundwater encountered
during tunneling would also be collected at the Airport Access Shaft location. The vertical tunnel
alignment from the Bair Island Inlet Structure Shaft location to the Airport Access Shaft location
slopes toward the Airport Access Shaft location. It is anticipated that water from within the tunnel
Component Airport Access
Shaft Construction
Tunneling Component
San Carlos Drop Shaft Construction
Estimated Excavated Material Quantity (LCY)
3,000 149,690 720
Hauling Trucks 3 8 1
Hauling Duration (weeks) 4 75 3
Average Round-Trip Haul Distance (miles)
24 24 24
Potential Disposal Site Ox Mountain Sanitary Landfill / Wetland Restoration Project Areas
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would flow at the tunnel invert to a sump location at the Airport Access Shaft and would be pumped
to the surface for temporary containment, treatment and disposal. The vertical alignment from the
Airport Access Shaft site to Flow Splitter Shaft slopes away from the Airport Access Shaft location to
the Flow Splitter Shaft. Water from the tunnel along this tunnel alignment would be captured
within the tunnel and pumped to the Airport Access Shaft location for temporary containment,
treatment and disposal.
Preliminary water infiltration estimates based on three (3) times the typical allowable leakage
criteria for final tunnel and shaft lining are provided below. This information will be refined by the
PDB.
Tunnel: 1.5-2 gallons per minute per 1,000 linear feet of tunnel (1.5-2 gpm/1,000 LF)
Shafts: 3 gpm
The groundwater infiltration from the tunnel and shafts would be cumulative over the length of the
tunnel. Based upon the preliminary estimates noted above, water flow to the Airport Access Shaft
would be approximately 40 gallons per minute (gpm) or approximately 55,000 gallons per day
(GPD).
Construction activities involving water management are regulated under the National Pollutant
Discharge Elimination System (NPDES) General Permit for Storm Water Discharges Associated with
Construction and Land Disturbances Activities (State Water Resources Control Board [SWRCB]
Order No. 2009-0009-DWQ, NPDES Permit No. CAS000002, and subsequent amendments generally
referred to as the General Permit [GP]). For this Project, the San Francisco RWQCB enforces the
General Permit. Coverage under a General Permit requires the submission to the SWRCB of the
Permit Registration Documents (PRDs) and receipt from the SWRCB of a Waste Discharge
Identification Number (WDID) for the Project.
Options for disposal of construction water include discharge to the storm drain, Redwood City’s
sanitary system or hauling offsite for deposal at a permitted facility. If construction water meets
the RWQCB water quality standards including effluent limitations and monitoring requirements it
may be discharged into the storm drain as allowed by the General Permit. Otherwise, the water
would be treated to concentration levels acceptable for discharge to the sanitary sewer. Non-
contaminated water that does not exceed the criteria set forth by Redwood City could potentially be
discharged into the sanitary sewer system. Prior to discharging into Redwood City’s sanitary sewer
collection system, the Contractor would be required to acquire a sewer discharge permit from
Redwood City. Coordination with Redwood City is required to determine the specific wastes and
discharges prohibited from entering the sewerage facilities.
Water handling facilities at this site are anticipated to include sump pump(s) for pumping
groundwater inflow from the Airport Access Shaft excavation to the surface, temporary
containment facilities and control measures such as sediment traps, sediment basin or Baker tank
to remove settleable solids prior to discharge to the storm drain system and/or sewer facility, and
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additional pumping equipment as necessary to pump/divert water adjacent storm drain system or
sewer facility. The need for additional treatment of the water prior to discharge would depend
upon water quality limitations at the proposed discharge location.
Contaminated water that cannot be treated onsite would require offsite transportation and offsite
disposal at a properly permitted treatment facility.
Requirements for discharge to the adjacent storm drain facilities at the Airport Access Shaft
location as well as Redwood City sanitary sewer facilities will be investigated further as the design
progresses.
4.2.5.4 Shaft Site Restoration and Permanent Facilities The shaft site construction staging area restoration would include site clean-up and re-grading of
the site to restore site slopes and drainage patterns and re-vegetation to grades near the original
grade unless otherwise approved by the landowner. Drainage would be restored towards the open
drainage facility located to the west and the wetlands located to the north and west of the site. The
constructions staging be would be re-vegetated or left as base as determined by the landowner.
Permanent facilities would include surface expression of the finished shaft manhole access
openings, including H-20 traffic rated access hatches or similar large equipment access opening and
H-20 traffic rated manhole frame and covers. These surface openings would be 3-6 inches above the
finished grade, and the area surrounding the manhole would be graded away from the openings.
The elevation will need to be confirmed with the landowner by SVCW.
4.2.5.5 Geotechnical Instrumentation and Monitoring The proposed location of the Airport Access Shaft will be in an open field adjacent to Holly Street
and Shoreway Road, which are both paved. It is expected that Holly Street may contain subsurface
utilities. There are also existing utility poles within the influence zone of the shaft. Considering the
fact, that there are no buildings in the close proximity of the shaft, the influence zone would extend
about 150 feet in order to monitor two roadways, Redwood Shores Parkway and the Airport Way
and their intersection. Further evaluation of the influence zone will be performed, taking into
consideration the selected initial support method.
The monitoring program proposed for the Airport Access Shaft excavation would include
instruments to measure vertical and lateral ground movements, settlement of utilities and tilting of
utility poles. Specifically, the type of instruments required for the project will include:
Settlement Indicator Points to measure pavement and utility settlements.
Subsurface Shallow Settlement Indicators to measure settlement of ground near surface.
Tiltmeters to measure rotational movement of utility poles.
Inclinometers installed adjacent to the initial shaft supports to measure lateral earth
movements as the shaft excavation progress.
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Prior to commencement of work, a pre-construction survey will be implemented to document the
existing conditions of all pavement structures and utility poles located entirely or partially within
the shaft excavation influence zone. The pre-construction survey will document condition of
pavement structures to provide a baseline data for evaluating construction claims.
4.2.6 Recommendations The following criteria were considered in evaluation of the Airport Access Shaft construction
methods:
shaft use
soil condition
groundwater levels
shaft construction cost
schedule
site restrictions such as airspace protection height limits
A comparison table of the four (4) initial support methods evaluated is presented below.
Table 4-14: Airport Access Shaft Initial Support Methods Comparison
Slurry Wall Secant Piles CSM Sheet Piling
Can be installed with
equipment meeting the FAA
height restriction of 62 feet.
However, the installation of
reinforcing cages in one unit
would require an
approximately 80-foot high
crane. The reinforcing cages
can be spliced vertically as
they are installed, but that
would be time consuming and
more costly.
Can be installed
with equipment
meeting the FAA
height restriction
of 62 feet.
Can be installed with
equipment meeting the
FAA height restriction of
62 feet. However, the
equipment has not been
used in United States yet
and procuring it may
impact the schedule and
cost of the shaft
construction.
Over 60 feet of
headroom would be
required to drive the
sheet piling in one
piece. The sheet
piling could be
installed in sections;
however, that would
increase the cost
and construction
duration.
Longest construction duration. Median
construction
duration.
Construction duration similar
to slurry walls.
Shortest construction
duration.
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For the Airport Access Shaft, it is recommended to use secant piles as the best suited construction
method. It will provide a relatively rigid support which will limit soil movements and settlements.
Although, the Airport Access Shaft is a temporary structure, the initial support method needs to be
sufficiently durable for the time span of construction. The shaft will be the center of all tunneling
activities. The utilization of secant piles fulfills this requirement. Upon completion, the shaft would
be backfilled, therefore, the most robust structure is not warranted. In addition, the shaft can be
constructed utilizing equipment not encroaching the FAA height restrictions, and not producing
significant construction noise and vibration.
$3.3 million construction
cost.
$3.0 million
construction cost.
$3.1 million construction
cost.
$2.8 million
construction cost.
Slurry Wall Secant Piles CSM Sheet Piling
Low construction site noise
and vibration level.
Low
construction site
noise and
vibration level.
Low construction site noise
and vibration level.
Significantly higher
level of noise and
vibrations than the
other options.
Robust initial support. Rigid structure. The soils at the Airport
Access Shaft are mainly
clay. Mixing clay with
cement will produce walls
with significantly lower
strength than slurry wall or
secant piles. Also, the
strength of the CSM is less
predictable and reliable.
Very thick walls (min. 5
feet) or additional
shotcrete layer would be
required.
Most flexible initial
support from all
proposed. This is
the only option
which would
require installation
of internal bracing.
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Shaft Construction
4.3 San Carlos Drop Shaft
4.3.1 Site Geology The information about general subsurface conditions at the San Carlos Drop Shaft is based on the
Phase I subsurface exploration program performed by Geotechnical Consultants Inc., and its
findings are presented in the "Preliminary Characterization of Subsurface Conditions" Technical
Memorandum dated December 9, 2015.
The existing subsurface conditions at the San Carlos Drop Shaft were developed from three borings
made at the proposed shaft location (B-107, B-111Pd and B-111Ps) in addition to in situ field and
laboratory test results performed on selected soil samples. The maximum boring depth obtained
was 71.5 feet below the ground surface. Piezometers were installed at boring locations B-111Pd
and B-111Ps.
Artificial Fill covers the site to a depth of 5 feet below the ground surface and consists of clay and
silt with varying amounts of sand/gravel. Varying quantities of organic materials, cobbles and
debris may be encountered within the fill. Young Bay Mud underlies the fill with a layer thickness of
12 to 18 feet. The Young Bay Mud consists of very soft to soft, highly compressible and plastic, near
normally consolidated fat clay. Zones of trace to abundant shell fragments, organic materials and
occasional thin layers of peat (less than a few feet in thickness) are contained within this layer.
Standard Penetration Test (SPT) results ranged from WOR to 10 blows/foot. Pocket penetrometer
field readings indicate an apparent undrained compressive strength of 900 to 2,100 psf.
Below the Young Bay Mud, Upper Layered Sediments are encountered with a layer thickness
between 48 and 51 feet. These soil deposits consist of complex alternating layers of lean clay, fat
clay, silty clay and silty sand, and sandy silt. The thickness, sequencing and consistency of these
individual layers are highly variable. SPT results ranged from 8 to 49 blows/foot. The fine grained
materials (silts and clays) have a generally stiff to hard consistency. Pocket penetrometer field
readings indicate an apparent undrained compressive strength ranging from 2,000 to over 9,400
psf.
Old Bay Deposits underlie the Upper Layered Sediments and extend to at least the bottom of the
deepest boring performed at this shaft site, a depth of 71.5 feet below the ground surface. This layer
of marine sediments consists of stiff to very stiff fat clay and lean clay with occasional scattered
shell fragments. SPT results ranged from 3 to 21 blows/foot. Pocket penetrometer readings indicate
an apparent undrained compressive strength of 2,800 psf.
Groundwater was encountered in boring B-111Ps at a depth of 13 feet below the ground surface
during boring operations. In addition, two water-bearing layers were encountered at depths of 16
feet and at 64 to 68 feet below the ground surface. Groundwater level readings in the installed
piezometers indicated that both of these layers have low permeability and are of limited extent.
Also, the water level readings (6.6 feet below ground surface) indicate that the upper layer may be
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unconfined and hydraulically connected to the Young Bay Mud deposit. The lower layer readings
(5.2 feet below ground surface) appear to be confined by the overlying thick layer of clay deposits.
4.3.2 Shaft Excavation
4.3.2.1 Excavation Size and Configuration The San Carlos Drop Shaft would be approximately 52-feet deep and 15 to 20-feet in diameter. The
centerline of the shaft will be offset approximately 20-feet from the centerline of the tunnel. A short
tunnel called an “adit” will be constructed to provide a connection between the shaft and the main
tunnel. The shaft will serve as a work area for the adit construction and provide sufficient space to
install a drop structure within the shaft. The size of the shaft will be selected based on the required
size of the drop structure and construction activities related to the adit construction. Details of the
drop structure are covered in TM No. 5 – Shaft Connections.
The optimal configuration for the San Carlos Drop Shaft would be circular in shape as it is the most
efficient in resisting the anticipated lateral loads. Circular shafts provide a rigid continuous support
and do not require internal bracing or toe embedment for stability. The adit could be constructed at
60 to 90 degrees angle to facilitate flow into the tunnel. The recommended angle is discussed in TM
No. 5.
4.3.2.2 Excavation Methods Conventional soil excavation techniques such as a crane and a clamshell bucket or an excavator can
be utilized to excavate the materials within the shafts. The excavated muck would be hoisted to the
surface by a crane directly in the clamshell or lifting buckets.
4.3.3 Initial Support
4.3.3.1 Support Methods and Evaluation Based on the soil conditions, site restrictions such as the FAA height limitation of 21 feet, the close
proximity of the existing 48-inch diameter force main and very limited staging area, only two initial
support methods were considered for the construction of the San Carlos Drop Shaft; the CSM and
caisson. Slurry walls, secant piles and sheet piling were excluded from the evaluation due to several
reasons. The slurry wall would require a utilization of a slurry separation plant and the compact
size of the site would not provide sufficient room for the plant. In addition, slurry walls would
require the installation of reinforcing cages which would require approximately 80 feet of
headroom clearance. Even though splicing of the reinforcement could be utilized, it would be
unpractical, costly and time consuming. The secant piles option would require slurry separation
plant on the site, similarly to the slurry walls or the placement of a temporary casing in the pile hole
to ensure the stability of the drilled hole before the tremie concrete is placed. The height limitation
and available space restriction make the slurry walls and secant piles options unfavorable and not
suitable for the San Carlos Drop Shaft construction. As for the sheet piling, driving of piles in close
proximity to existing utilities and buildings would be prohibited due to noise and vibrations
produced during installation.
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In the area where the adit will be constructed and connected to the tunnel, a soil improvement zone
would be required to stabilize the ground and allow for the adit excavation (refer to Figure 4-31
and 4-32). Two options are considered for the ground improvement: the CSM and jet grouting. The
ground improvement using either method would minimize water inflow during excavation and
enhance the stand-up time providing stable working conditions during adit excavation.
Hand tunneling will be utilized for the construction of the adit and its connection to the tunnel. This
method is typically performed by tunnel miners using compact equipment or hand tools to excavate
the soils. It is envisioned that the adit would be a modified horseshoe shape. A sequential
excavation method could be utilized for the construction of the adit and the adit to tunnel
connection. This approach would involve dividing the adit cross section into two areas: heading and
bench. The heading would be excavated first. Reinforced shotcrete would then be installed to
provide excavation support. After the heading is completed, the bench would be constructed. This
method would minimize the stresses in the ground around the opening. The need for implementing
this method will depend on the size of the adit and will be evaluated further during the design stage
of the project.
A mud slab will be installed at the shaft invert to provide a smooth and firm working surface for
adit construction activities taking place in the shaft. A breakout for the adit in the shaft wall will be
designed and the walls will be strengthened with additional reinforcement to efficiently resist the
breakout forces developed in the shaft.
CSM
The CSM method would consist of mixing cement with native soil to create a relatively impermeable
and stable zone as shown in Figure 4-31. A layer of reinforced shotcrete, approximately 9 to 12
inches thick, will be installed as the shaft excavation progresses to provide structural stability of the
system.
The CSM could be also used for the ground improvement around the adit and adit to tunnel
connection. The soil improvement would be constructed prior to excavation of the tunnel and shaft.
The strength of the zone would be designed to allow for the soft ground TBM to mine through this
zone and allow for the construction of the adit and adit to tunnel connection.
The CSM method is the more suitable and cost efficient initial support system for the San Carlos
Drop Shaft. The same equipment could be utilized to construct both the shaft and the soil
improvement, saving cost and time on mobilization of a new system. However, the equipment
available and commonly used in the United States for CSM wall at the depth of this shaft is
approximately 70 feet high. This exceeds the FAA height restriction of 21 feet (refer to section
4.3.5.4 for the FAA height restrictions). Low overhead CSM equipment had been used on several
overseas project. Procuring this equipment for this project is possible, however it could have a
negative impact on the shaft construction schedule and cost.
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Shaft Construction
Figure 4-31: CSM Alternative
Caisson
It is envisioned that approximately 1'-6" reinforced concrete wall would be required to effectively
resist the forces on the caisson shaft. The shaft lining could be precast or cast in place, constructed
at the surface at the location of the proposed shaft wall, in vertical sections, and then lowered into
the ground as excavation progresses. The caisson can be installed using a gantry or small crane,
both with low height under 21 feet. The caisson construction would start with an excavation of the
shaft area to a depth of few feet and the installation of a cast-in-place concrete collar. The collar
would provide support for the surcharge load at the surface, resist the forces from hydraulic jacks,
and act as a guide for shaft sinking.
In the area where the adit will be constructed to connect the shaft and the tunnel, a soil
improvement zone is required to stabilize the ground and to allow for the construction of the adit
(Refer to Figure 4-32). It is anticipated that with the Caisson shaft construction method, jet
grouting soil improvement would be utilized. Jet grouting can be performed from the surface or
from the shaft after the shaft is constructed. If performed from the surface, the equipment for jet
grouting is available in heights within the 21-foot restriction, but adding stems (splicing the
sections) would be required. For jet grouting from the shaft, the equipment can be placed within
the excavation, therefore not encroaching on the height mandated by the FAA.
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Planning Level Technical Memorandum No. 4
Shaft Construction
Figure 4-32: Caisson Alternative
Comparison Cost
Relative comparison costs for the San Carlos Drop Shaft impermeable system options are shown in
Table 4-15. The costs were developed in 2015 prices. Mark-ups of 25 percent for indirect costs and
15 percent for overhead and profit are included in the costs. The costs do not include contingency
and escalation. Refer to Appendix A.
Table 4-15: San Carlos Drop Shaft Initial Support Cost Comparison
Initial Support Method
Initial Support Cost + Soil
Improvement
(Millions)
CSM $2.2
Caisson $2.6
4.3.4 Groundwater Control at San Carlos Drop Shaft No special groundwater mitigation at the bottom of the shaft is expected at the San Carlos Drop
Shaft location. The CSM soil improvement implemented at the shaft site would allow for relatively
dry excavation.
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4.3.5 Site Conditions The San Carlos Drop Shaft site is located at the northwest end of Monte Vista Drive adjacent to the
San Carlos Airport in the City of San Carlos on the San Carlos Pump Station (SCPS) property, owned
by the City of San Carlos. This site will serve as the construction area for the San Carlos Drop Shaft.
This shaft will be used to construct an adit to the tunnel and ultimately to connect and divert
Belmont and San Carlos wastewater flow to the proposed gravity pipeline which will be installed
within the tunnel.
4.3.5.1 Site Ingress/Egress Access to the San Carlos Drop Shaft site would be provided from Skyway Road and Monte Vista
Drive. The site location and ingress and egress to/from the site from Highway 101 and surrounding
areas is shown in Figure 4-33.
Figure 4-33: San Carlos Drop Shaft Site Ingress and Egress
Specific ingress/egress gate location and access requirements within the site for construction
vehicles is considered in the site staging requirements for the site and is discussed in further detail
in Section 4.3.5.3.
Shaft Construction Site
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4.3.5.2 Existing Site Conditions The SCPS located at this site is active and currently pumps wastewater from the City of San Carlos
and unincorporated areas of San Mateo County into the SVCW force main system. The pump station
building is located to the west to the staging area and is enclosed with chain link fence. There are
two access gates to the pump stations one located at the northeast end of the site and another
located at the southwest end of the site. At the southeast side of the building, there is structure
with above grade access to a valve vault. This valve vault contains diversion gates utilized to route
flow from the existing 48-inch force main which is located directly under the vault into the San
Carlos PS during wet weather flows. The exiting 48-inch force main is aligned along the north east
boundary of the site and will be crossed by the Gravity Pipeline alignment (below) at the valve vault
location. Overhead power lines are located on the east side of the site, over the southern access
driveway to the SCPS. Based upon work on the 48-inch Force Main Reliability Improvement Project
Unit 3 along Monte Vista Drive (not constructed), the overhead power wires most likely include
primary conductors with nominal voltage of 12 kV.
There is a transformer and electrical facilities located near the middle of the site in front of the
pumps station in a landscaped area. The power pole adjacent to the transformer has a guy wire and
below-grade anchorage for the guy wire. The site is mainly paved with a small landscaped area
with irrigation facilitates located on the east side, adjacent to Monte Vista Drive. The site slopes
approximately 5-7 percent from west to east towards a paved access road, which has catch basins
on either side. There is an existing SCA access gate (Gate W-1) and automatic gate keypad and
associated conducted located at the end of Monte Vista Drive. Various underground utilities are
located at the site including potential high voltage electrical facilities (to be confirmed), 36-inch
gravity sewer, 48-inch sanitary sewer force main, valve vault structure, 12-inch RCP storm drain,
12-inch potable water main and associated lateral, communication and gas utilities.
Electrical facilities and unknown metal reading utility markings have been identified at the
proposed shaft location and will require further investigation to address potential conflicts with
these utilities as the design progresses.
4.3.5.3 Staging Area Requirements Due to the existing paved condition of the site, clearing and grubbing of this site prior to staging
would not be required. The space available for staging and construction of the San Carlos Drop
Shaft at this location is limited. The following site constraints have been considered in developing
shaft staging area requirements:
Continued access to the existing SCPS during shaft construction.
Location of existing above grade facilities including overhead electrical wires and
other facilities which require protection during construction including the pump
station building, existing power poles, transformer and above grade piping located
adjacent to pump station building.
Continued access to SCA access gate (Gate W-1) during construction.
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Planning Level Technical Memorandum No. 4
Shaft Construction
Access to the existing Hiller Aviation waste bin structure located at the end on Monte
Vista Drive.
The following additional items have been considered in developing the construction staging area
requirements:
Shaft Location relative to overall staging area
Shaft excavation size, configuration and equipment required for the recommended
caisson shaft construction method
Site access to the SCPS from public right-of way
Design Vehicle Type: WB-40 (semi-trailer with 40-foot wheel base)
Shaft Excavation Rate: Approximately 4 vertical linear feet (VLF) per day
Due to the limited space available, the shaft excavation materials will not be stored onsite prior to
hauling to the ultimate disposal location. Excavated material from shaft from this site will be stored
at the Airport Access Shaft site, approximately 1 mile away from the San Carlos Drop Shaft site.
Although the overall SCPS site is approximately 0.6 acres, the majority of the staging area will be
located in front of the pump station in an area encompassing approximately 0.2 acres if storage is
necessary. The staging plan for the San Carlos Drop Shaft site is shown in Figure 4-34.
SAN CARLOS AIRPORT
M
onte V
ista D
r
S
k
y
w
a
y
R
d
IZZY'S STEAKS & CHOPS
F
A
IR
F
IE
LD
IN
N
&
S
U
IT
E
S
S
A
N
F
R
A
N
C
IS
C
O
S
A
N
C
A
R
LO
S
STAGING AREA
1
L PROPOSED 15'Ø OD TUNNEL
P
U
M
P
S
T
A
T
IO
N
2
C
1
SAN CARLOS DROP SHAFT STAGING AREA - PLAN
APPROX 0.6 AC
3
4
3
5
SEE NOTE 1 & 2
(E) PARKING
(E) WASTE BIN STRUCTURE
LEGEND
1. ENTRY/EXIT GATE
2. GENERATOR
3. STORAGE BOXES
4. COMPRESSOR
5. EMERGENCY GATE
6. K-RAIL
7. EXCAVATED MATERIAL LOADING AREA
8. VEHICLE: WB-40
9. WATER TREATMENT FACILITIES
T
H
E
M
IC
H
A
E
L K
IN
G
S
M
IT
H
R
E
S
E
A
R
C
H
LIB
R
A
R
Y
NOTES:
1. FOR ADDITIONAL STAGING AREA REFER TO AIRPORT ACCESS SHAFT STAGING AREA FIGURE 4-30.
2. PUMP STATION ACCESS MAINTAINED
THROUGHOUT CONSTRUCTION.
B
U
R
G
E
R
K
I
N
G
7
Kennedy/Jenks Consultants
SILICON VALLEY CLEAN WATER
TUNNEL PROJECT - TM No. 4
SAN CARLOS DROP SHAFT
SITE STAGING PLAN
0
1"=60'
60 10030
(E) POWER POLE
(E) GUY WIRE
CAISSON INSTALLATION
EQUIPMENT / CRANE WORKING ZONE
(E) AIRPORT ACCESS GATE
W-1 MAINTAIN ACCESS
20' OUTSIDE DIA.
SAN CARLOS DROP SHAFT
6
FAA AIRSPACE PROTECTION SURFACES (SEE NOTES)
9
K/J 1568063.02 JUNE 2016
FIGURE 4-34
FAA AIRSPACE PROTECTION NOTES:
1. AIRSPACE PROTECTION SURFACE ELEVATIONS ON THIS EXHIBIT ARE EXPRESSED IN FEET
ABOVE MEAN SEA LEVEL (MSL). THE ELEVATION OF SAN CARLOS AIRPORT IS 5 FEET MSL.
2. LOCATIONS WHERE THE GROUND/TERRAIN PENETRATES THE FAR PART 77 AIRSPACE
SURFACES ARE APPROXIMATE AND WERE DEVELOPED USING ALUCP EXHIBIT 4-4 WHICH
UTILIZED GROUND ELEVATION CONTOURS PROVIDED BY THE SAN MATEO COUNTY
PLANNING AND BUILDING DEPARTMENT 2014.
3. SOURCE: SAN CARLOS AIRPORT ALUCP, EXHIBIT 4-4 (ESRI, 2014; SAN MATEO COUNTY
PLANNING AND BUILDING DEPARTMENT, 2014; ESA AIRPORTS, 2014).
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The staging area will include limited space for caisson construction equipment a generator, two
storage boxes and compressor. An area for excavated material loading is designated on the plan. It
is anticipated a 40 cubic yards container would temporarily hold the excavated material during the
day’s excavation activities and would be hauled off to the Airport Access Shaft site 1 to 2 times a day
during shaft excavation.
Based upon the proposed layout, vehicles exiting the SCA Gate W-1 would access Monte Vista Drive
through the adjacent parking area. Similarly, access to and from the existing waste bin structure
would be through the existing adjacent parking lot. Coordination with Michael King Smith Research
Library and Hiller Aviation Museum will be required.
Sufficient space is not available for construction vehicles to make a U-turn at the site; however
construction vehicles can access the site and back into the gate, as shown on Figure 4-34, for turn
around. The largest vehicle that can be accommodated at this site is a WB-40 vehicle. Additional
staging for construction crew parking, lockers and material storage needed for shaft constriction
will be provided at the Airport Access Shaft site.
4.3.5.4 San Carlos Airport and Federal Aviation Administration Considerations The San Carlos Drop Shaft staging area is located within the San Carlos Airport (SCA) Inner
Approach/Departure Zone. In addition, the staging area for this site also encroaches into the
Runway Protection Zone. Refer to TM No. 1, Appendix A (Exhibit 4-3) for SCA safety zones.
FAA Airspace protection surfaces across the San Carlos site staging area are shown Figure 4-34.
The staging area is primarily located within 25-foot to 47-foot airspace protection elevation
contours. It should be noted these contour elevations represent an elevation in feet above mean
sea level. Based upon the location of these contours across the staging area, the estimated
protection surface elevation above the existing site grade elevation is estimated to be 21-33 feet
above grade near the equipment/crane working area. Refer to Table 4-16 for additional
information. Caisson installation equipment can be procured with an overall height below the FAA
height restrictions for this location, avoiding encroachment in the protection surface elevation. The
overall height of a conventional crane and equipment for installation of the drop structure and shaft
finish-out is anticipated to be approximately 40-feet in height. Potential encroachment into FAA
airspace during shaft finish-out work would require night work and would be limited to 2-3 non-
consecutive days.
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Table 4-16: San Carlos Drop Shaft Airspace Protection Height Restrictions
Notes:
(a) Heights are based upon SCA Part 77 Airspace Protection Surfaces, SCA 2015 ALUCP Exhibit 4-4. Height represents
lowest height within the preliminary anticipated equipment/ crane working zone.
(b) Based upon preliminary site elevations using project vertical datum of NGVD 29 + 100 feet. Grade elevation relative
to MSL was determined by subtracting 100 feet from the preliminary site elevations.
Proposed construction at this location is subject to review and approval by the Federal Aviation
Administration (FAA) (as administered by the SCA) and requires an FAA Form 7460-1 be
submitted. Specific FAA requirements and conditions associated with the proposed construction
and anticipated crane height encroachment into the in the FAA jurisdictional areas for the site
would be included in the Notice of Determination by the FAA.
4.3.5.5 Utility Requirements Utility requirements during construction include protection of existing facilities identified in
Section 4.3.5.2. Temporary k-rail would be installed around the existing transformer, power pole
and associated guy wire to protect these utilities in-place during construction. Potholing of existing
electrical conduit(s) and unknown utility located in the proposed shaft location is recommended to
confirm locations and establish a relocation plan for the utilities prior to shaft construction.
Additional investigation and coordination with PG&E is required to determine the specific
requirements for temporary power during construction, confirm nominal voltage of existing power
lines, and confirm required clearances from the existing facilities. Although the overhead power
lines do not cross over the proposed shaft excavation area, the overhead power wires likely include
primary conductors with nominal voltage of 12kV. The California Division of Occupational Safety
and Health (Cal/OSHA) regulations require minimum safe working and traveling distances be
maintained from cranes to overhead electric lines which are often more stringent than PG&E
clearance requirements.
Tables 1-2 and 1-3 included in PG&E’s Green Book note the minimum Cal/OSHA safe working distances from 0.6 to 50 kV nominal voltage conductors are as follows:
Boom-type lifting or hoisting equipment: 10 feet
Scaffolds, equipment, tools, structures, and people: 6 feet
Although the space at this location is limited, it is not likely that the operation of the crane and
caisson construction equipment will encroach within the 10-foot clearance requirement for crane
type equipment. A 10-foot horizontal buffer from the existing conductor would be located outside
Site Height Restriction
(Feet Above MSL)(a)
Grade Elevation (relative to MSL)(b)
Estimated Height Limit Above Existing
Grade Elevation
San Carlos Drop Shaft 25 - 37 4 21 - 33
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of the caisson construction equipment and crane operation area. It is understood OSHA’s clearance
requirement is from the primary conductor and not necessarily on the horizontal plane. The
horizontal buffer provides a reference point considering the height of the primary conductors
relative to the crane is unknown at this time. Confirmation of the nominal voltage of existing
overhead power lines and coordination with PG&E is required to confirm these clearance
requirements and confirm temporary relocation during construction is not required.
Additional utility requirements and considerations for this site are provided below:
Temporary power requirements: 480V, 3 phase, 4-wire Potable water: Access to potable water is available onsite. The Contactor would be
responsible for installing backflow prevention and metering devices. Temporary portable restroom(s) would be provided during construction. Protection of existing 48-inch sanitary sewer force main.
4.3.5.6 Long Term Operation and Maintenance Facility Requirements Infrequent operation and maintenance (O&M) activities are anticipated for the San Carlos Drop
Shaft. A vortex drop structure will be installed within the San Carlos Drop Shaft. Although vortex
structures are typically designed to convey wastewater flow at self-cleaning velocities,
accumulation of debris and material over time should be anticipated due to the spiral configuration
of vortex units and debris that is often carried in raw wastewater. However, wastewater from
Belmont Pump Station will pass through a coarse bar screen and demuter and San Carlos flow will
pass through coarse bar screens upstream of the drop structure which will help to minimize the
accumulation of debris. The frequency for cleaning of the vortex structure will depend upon actual
flow conditions and wastewater characteristics. Based upon on the reported required frequency of
cleaning for utilities with installed vortex structures, cleaning of the vortex structure can be
anticipated to occur once every 5 to 10 years. Cleaning is usually performed by a third-party
contractor. Cleaning crews typically utilize a tripod with a safety harness to lower maintenance
staff off a winch into the manhole.
The following features are recommended for optimum cleaning:
Access for an 8-wheel, dual axle vacuum truck approximately 42 feet long with a 30-foot wheel base.
All weather access approach capable of handling the load of a vacuum truck filled with 3,000 to 4,000 gallons of water.
Open vortex top to allow for removal of debris accumulation at the top of the vortex structure.
Access opening over the top of the vortex structure. Maintenance platform/bench above the flow. Minimum of two large manhole ring and cover openings, one over the vortex structure and
another over the work bench or a corrosion resistant double-door hatch (Bilco type hatch, 6’ x 6’ or 4’ x 8’) over the platform and vortex structure.
Multiple openings (one over the vortex structure) can eliminate confined space entry. Harness Tie-offs (anchor bolts of 316SS).
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4.3.6 Construction Considerations
4.3.6.1 Mobilization Mobilization will include all activities for transportation of contractor's personnel, equipment, and
operating supplies to the San Carlos Drop Shaft staging site necessary for shaft construction. Due to
the limited space available at the San Carlos Drop Shaft staging area, the Airport Access Shaft site
will also be used by the San Carlos Drop Shaft Contractor, as an additional staging area for field
office and any necessary general facilities. The mobilization of the San Carlos Drop Shaft site will
include installation of temporary equipment, fencing, gates and utilities necessary for the
Contractor's operations at the site. For more details on the SCPS shaft staging area, refer to the
"Staging Area Requirements" section above. Mobilization will also consist of the Contractor
obtaining all required insurance, bonds and permits.
4.3.6.2 Excavated Material Handling The SCPS site has limited space for construction activities. For this reason, excavated material
produced from the shaft excavation activities will likely be hauled to the Airport Access Shaft site
for characterization and hauling and disposal. The total estimated quantities for excavated material
from the San Carlos Drop Shaft site are included in Table 4-13. It is anticipated the excavated
material would be temporarily placed in on onsite 40-yard dumpster or placed directly onto a
dump truck for daily hauling to the Airport Access Shaft site. Based on the anticipated shaft
excavation rates it is anticipated the dumpster would be retrieved and emptied at the Airport
Access Shaft site twice, daily during shaft excavation.
4.3.6.3 Water Treatment and Disposal Groundwater was encountered during geotechnical investigations at the SCPS site. Geotechnical
investigations indicate the water bearing layers have low permeability. The soil improvement
implemented at the shaft site described herein would allow for relatively dry excavation. Should
water handling facilities be needed at this site they would include sump pump(s) for pumping
incidental groundwater inflow from the shaft excavation to the surface, and temporary containment
facilities to remove settleable solids prior to discharge. The options for discharge of groundwater
are similar to those discussed for the Airport Access Shaft site. However, in this case the storm
drain and sanitary sewer facilities are owned by the City of San Carlos. Sanitary sewer facilities and
storm drain facilities are both located adjacent to the shaft site.
Further coordination is required during predesign to establish potential allowable discharge flow
rates into the SCPS wetwell to avoid potentially overloading of the sewerage facilities, although
large quantities of water are not anticipated at this site.
4.3.6.4 Shaft Site Restoration and Permanent Facilities After the new gravity sewer conveyance system is in service, the existing San Carlos Pump Station
(SCPS) would no longer be required. The SCPS would be decommissioned and repurposed by
others. Final site restoration is anticipated to be performed by others following the repurposing of
the SCPS. The repurposing of the SCPS would include construction of improvements required to
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connect the flow from the Cities of San Carlos and Belmont to the new gravity pipeline are
complete.
Permanent facilities at the shaft would include the drop structure within the shaft, and access
openings discussed in section 4.3.5.6. An air handling pipe is anticipated to be constructed from
within the drop shaft to air handling facilities anticipated to be constructed (by Others) at the
existing San Carlos Pump Station location. Permanent access approach to the shaft would be asphalt
concrete paved. In the interim, it is anticipated temporary hot mix asphalt would be placed in the
area surround the permanent shaft facilities.
4.3.6.5 Geotechnical Instrumentation and Monitoring The proposed location of the San Carlos Drop Shaft will be in a paved area adjacent to the SCPS, the
San Carlos Airport taxiway, the Monte Vista Drive and the existing 48" force main. The area
contains various subsurface utilities. There are also existing building structures in vicinity of the
shaft. Therefore, the monitoring program proposed for the SCPS Shaft excavations would include
instruments to measure vertical and lateral ground movements, vertical and lateral structure
movements, settlement of utilities, and groundwater fluctuations outside of the shaft excavation.
Specifically, the type of instruments required for the project will include:
Surface Settlement Markers installed on building walls and foundations to measure vertical
displacement.
Tiltmeters to measure rotational movement of utility poles.
Crackmeters to determine if existing cracks in structures are progressively widening.
Settlement Indicator Points to measure pavement and utility settlements.
Subsurface Shallow Settlement Indicators installed adjacent to foundations to measure
settlement.
Inclinometers installed adjacent to the initial shaft supports to measure lateral earth
movements as the shaft excavation progresses.
Control groundwater observation wells installed adjacent to the shaft excavation to
measure groundwater levels.
Prior to commencement of work, a pre-construction survey will be implemented to document the
existing conditions of all structures and pavement located entirely or partially within the shaft
excavation influence zone. The zone of influence would be determined based on a site specific
evaluation to determine which structures need to be monitored. The instrumentation would be
installed at all structures, roadways and other objects of concern located within approximately 200
feet from the shaft. Further evaluation of the influence zone will be performed, taking into
consideration the selected initial support method. The pre-construction survey will document
interior and exterior condition of all structures and pavements to provide a baseline data for
evaluating construction claims.
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4.3.7 Recommendations The San Carlos Drop Shaft site is the smallest and most congested shaft location on the project. With
the surface utilities, the existing pump station, and very close proximity of the San Carlos Airport,
the smallest equipment footprint possible is best suited for this site. Two shaft initial support
methods are considered for the San Carlos Drop Shaft: CSM and Caisson. It is envisioned that CSM
could be also utilized for the soil improvement at the adit where CSM shaft construction methods is
used, otherwise jet grouting would be suggested. A comparison table of the two initial support
methods evaluated is presented Table 4-17 below.
Table 4-17: San Carlos Drop Shaft Initial Support Comparison
CSM Caisson with Jet Grouting for Soil Improvement
Can be installed with equipment
meeting the FAA height restriction of
21 feet. However, the equipment has
not been used in United States yet and
procuring it may impact the schedule
and cost of the shaft construction
Can be installed with equipment meeting the FAA
height restriction of 21 feet.
$2.4 million construction cost $0.5 million construction cost.
Shorter construction duration. The
construction time is relatively rapid if
no obstructions are encountered.
Longer construction duration. The construction
time is longer due to the need of collar installation
and jet grouting for ground improvement.
The same equipment would be utilized
to construct the shaft and the soil
improvement saving time on mobilizing
new equipment.
Separate equipment would be used for the soil
improvement and for shaft construction.
Procuring low headroom equipment
could negatively affect the construction
schedule and cost.
Jet grouting can be utilized for ground
improvement, but splicing is required which
increases the cost and time of construction.
Low construction site noise and
vibration level.
Low construction site noise and vibration level.
The final lining would be cast in place
shotcrete which would provide
relatively smooth walls.
The caisson final lining will provide uniform
interior surface.
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The suggested method of shaft construction is the caisson option. The caisson installation
equipment can be procured with an overall height below the 21 foot limit. All other methods
exceed the FAA height restriction.
For the required ground modification at the adit connection between the shaft and the tunnel, the
use of jet grouting is deemed optimal. The grouting can be performed from the surface or within the
shaft after excavation and the required equipment can be obtained to be below the FAA height
restriction limit. With jet grouting, the difficulties with height of equipment and any potential
interference with the existing 48-inch force main are eliminated.
4.4 Bair Island Inlet Structure Shaft
4.4.1 Site Geology The information about general subsurface conditions at the Bair Island Inlet Structure Shaft is
based on the Phase I subsurface exploration program performed by Geotechnical Consultants Inc.,
and its findings are presented in the "Preliminary Characterization of Subsurface Conditions"
Technical Memorandum dated December 9, 2015. The available data from currently ongoing Phase
II geotechnical investigation program was also utilized to confirm the information used from the
Phase I investigation program.
The existing subsurface conditions at the Bair Island Inlet Structure Shaft were developed from
three borings made at the proposed shaft location (B-108, B-112Pd and B-112Ps) in addition to in
situ field test results performed on selected soil samples. The maximum boring depth obtained was
74.5 feet below the ground surface. Piezometers were installed at boring locations B-112Pd and B-
112Ps. No laboratory tests were performed on soil samples obtained at this shaft location.
Artificial fill covers the site to a depth of 13 to 17 feet below the ground surface and consists of clay
and silt with varying amounts of sand/gravel. Varying quantities of organic materials, cobbles and
debris may be encountered within the fill. Young Bay Mud underlies the fill with a layer thickness of
up to 4 feet. The Young Bay Mud consists of very soft to soft, highly compressible and plastic, near
normally consolidated fat clay. Standard Penetration Test (SPT) results generally varied from
weight of rods (WOR) to 3 blows/foot.
Below the Young Bay Mud, Upper Layered Sediments are encountered with a layer thickness of at
least 46 feet and in some cases extend to at least the bottom of the deepest boring performed at this
shaft site, a depth of 74.5 feet below the ground surface. These soil deposits consist of a complex of
alternating layers of lean clay, silty clay, silty sand, sandy clay, and clayey gravel. The thickness,
sequencing and consistency of these individual layers are highly variable. SPT results ranged from 9
to 34 blows/foot. The fine grained materials (silts and clays) have a generally stiff to hard
consistency and the granular materials (sands and gravels) are in a medium dense to dense state.
Pocket penetrometer field readings indicate an apparent undrained compressive strength ranging
from 3,500 to over 6,500 psf. Old Bay Deposits underlie the Upper Layered Sediments and extend to
at least the bottom of the deepest boring performed at this shaft site, a depth of 74.5 feet below the
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ground surface. This layer of marine sediments consists of stiff to hard silt with varying amounts of
sand/clay and lean clay with occasional scattered shell fragments. Standard Penetration Test (SPT)
results ranged from 32 to 40 blows/foot. Pocket penetrometer readings indicate an apparent
undrained compressive strength of 7,000 to 7,400 psf.
Groundwater bearing layers were encountered at depths of 22 to 32 feet and 46 to 49 feet below
the ground surface. Piezometers installed at borings B-112Pd and B-112Ps indicated static water
levels at a depth of 7.5 feet below the ground surface at both locations. This level is consistent with
the water level at an adjacent water body and indicates that the water-bearing layers are
hydraulically connected to the surface water bodies.
4.4.2 Shaft Excavation
4.4.2.1 Excavation Size and Configuration At this shaft location, a connection will be constructed between the new gravity sewer to the
recently completed existing high density polyethylene (HDPE) 48-inch force main sewer. The shaft
will serve as a temporary structure required for the construction of the connection and as a
receiving shaft for the TBM. Based on the construction activities and requirements for the
connection to the existing sewer, it was determined that the Bair Island Inlet Structure Shaft will be
a rectangular pit, 25 x 42 feet in plan dimension and approximately 27 feet deep. After retrieving
the TBM and constructing the sewer connection, an access structure and ogee pipe connection to
the existing 48-inch force main will be installed within the shaft. The annular space between the
access structure and the shaft will be backfilled. Details of the sewer connection and the access
structure are rendered in Planning Level TM No. 5.
4.4.2.2 Excavation Methods Conventional soil excavation techniques such as a crane and a clamshell bucket or an excavator can
be utilized to excavate the materials within the shafts. The excavated muck would be hoisted to the
surface by a crane directly in the clamshell or lifting buckets.
4.4.3 Initial Support
4.4.3.1 Support Methods and Evaluation From the five initial support methods selected for the project, only three have been considered for
the Bair Island Inlet Structure Shaft construction, namely: secant piles, CSM and sheet piling. The
caisson and slurry wall initial support methods were excluded due to anticipated higher cost and
their complexities of construction comparing to the selected systems. A conceptual design was
performed for each of the remaining systems to estimate its size and applicability for this location
under the anticipated lateral loads.
The following geological conditions have been considered in the design of support of shaft
excavation: the first 13 feet of the shaft would be constructed in very soft Artificial Fill, followed by
up to 4-feet of very soft to soft Young Bay Mud, then 10 feet of loose to very stiff Upper Layered
Sediments.
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Secant piles
It is anticipated that approximately 2.5 feet diameter reinforced piles would be required to
adequately resist the lateral pressures and accommodate the vertical construction tolerances (refer
to Figure 4-35). Every second pile would be reinforced with a wide flange steel shape or steel
reinforcement cages. An installation of internal bracing consisting of wales and struts would be
required. The bracing will be placed as the excavation progresses. A mud slab would be poured at
the shaft invert to provide smooth and firm working surface for the activities taking place in the
shaft. The secant piles would provide a relatively rigid initial support limiting soil movements and
settlements. The secant pile system is commonly used and can be installed with low overhead
clearance requirements of 21 feet and less.
Due to the presence of water bearing granular layers at the tunnel level, soil improvement would be
implemented for ground at the tunnel breakout to prevent water ingress into the shaft during
breaking in for the TBM retrieval. In addition, a seal around the tunnel breakout inside of the shaft
would be installed to aid in minimizing the groundwater inflow into the shaft.
Figure 4-35: Secant Pile Alternative
Cutter Soil Mixing (CSM)
It is anticipated that approximately 2-foot thick CSM walls would be required for shaft construction
(refer to Figure 4-36). The walls would need to be reinforced with steel wide flange shapes
embedded in the walls and supported with shaft internal bracing. Typically, wales and struts are
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used for wall bracing. The bracing would be installed as the excavation progresses. A mud slab
would be poured at the shaft invert to provide a smooth and firm working surface for the activities
taking place in the shaft. The CSM would provide a relatively rigid initial support, limiting soil
movements and settlements. The CSM system can be installed with a low overhead clearance
requirement of 21 feet and less. However, the equipment available and commonly used in the
United States is approximately 60 feet in height and above. This exceeds the FAA restriction of 49
feet (refer to section 4.4.4.4 for FAA height restrictions). The CSM low overhead equipment has
been used on several overseas projects. However, it is not readily available in the United States.
However, it is not readily available in the United States. Procuring this equipment for this project
may have a negative effect on the shaft construction schedule and cost.
Similarly to the secant pile option, soil improvement and a seal at the tunnel breakout would be
used to prevent groundwater ingress into the shaft during breakout for TBM retrieval.
Figure 4-36: Cutter Soil Mixing Alternative
Sheet Piles
To support the excavation, steel sheet piling would be driven to follow the rectangular
configuration of the shaft (refer to Figure 4-37). The sheet pile wall would be constructed in
conjunction with the shaft's internal bracing consisting of wales and struts. The bracing would be
installed as the excavation progresses. A mud slab would be poured at the shaft invert to provide a
smooth and firm working surface for the activities taking place in the shaft. The sheet piles would
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be the most flexible shaft initial support method from all proposed for the SVCW project. Similarly
to the other options, soil improvement and a seal at the tunnel breakout would be used to prevent
groundwater ingress into the shaft during breakout for TBM retrieval.
In addition, approximately 40 to 60 feet of headroom would be required to install sheet piling at the
Bair Island Inlet Structure. The exact height clearance required will depend on the depth of the
sheet piling to be driven. Splicing and welding of sheet piling could be utilized to adhere to the FAA
height limit of 49 feet (refer to section 4.4.4.4 for FAA height restrictions). However, this would
increase the cost and duration of the shaft construction.
Figure 4-37: Sheet Piling Alternative
Groundwater Control at Bair Island Inlet Structure Shaft
Only an impermeable shaft support system will be utilized for the Bair Island Inlet Structure Shaft
construction. Since the shaft would be terminated in or near the water-bearing granular soil layer,
the construction of a sealing element at the shaft invert will be required to minimize water inflow
into the excavation and to facilitate construction. The sealing element at the shaft invert, in
conjunction with the impermeable excavation support, would provide a relatively impervious
system minimizing the groundwater inflow into the shaft. The following five options of impervious
systems have been investigated:
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Option 1 - Extended initial support
This system would include the extension of the excavation support system into the impermeable
layer (refer to Figure 4-38). The shaft lining would be extended approximately 25-feet down
through the permeable layers of Upper Layered Sediments into the lower relatively impermeable
silts and clays of the Old Bay Deposits to provide a groundwater cut-off barrier. This option would
minimize the water inflow into the excavation during the construction of the shaft and the sewer
connection.
Figure 4-38: Extended Excavation Support
The advantages and disadvantages of this system are listed in Table 4-18 below.
Table 4-18: Advantage and Disadvantage – Option 1
Advantages Disadvantages
Fast installation since only the
support will be extended
The height of the CSM and sheet piling
equipment required for the installation of the
extended support may encroach on the FAA
height restriction of 49 feet.
Relatively low cost since
equipment will be onsite
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Option 2 - Excavation support and permeation grouting curtain
In lieu of extending the excavation support into the impermeable layer, a water cut-off barrier could
be constructed. The barrier would be formed by utilizing permeation grouting (refer to Figure 4-
39). Another type of soil improvement could be used in lieu of permeation grouting, such as jet
grouting or soil freezing. However, it is anticipated that the cost of these systems would be much
higher than permeation grouting or extended excavation support (Option1). Therefore, they are not
recommended at this time. The additional soil improvement methods (jet grouting and soil
freezing) may be revisited during preliminary design if determined that they are best suited for the
construction of the shaft.
The permeation grouting would be accomplished from the surface before the shaft excavation
begins. Two grout placement methods could be used. A series of holes could be drilled along the
shaft perimeter or through grout pipes embedded in the excavation support. A low viscosity grout
would be injected into in-situ soil at relatively low pressures allowing the grout to permeate into
the soils. The installation of a grouting curtain would minimize the water inflow into the shaft
during construction; however, it would require substantially more labor and cost for verification
(testing) than Option 1. Therefore, the impermeable excavation support and permeation grouting
option is not recommended and excluded from further investigation.
Figure 4-39: Permeation Grouting Curtain
The advantages and disadvantages of this system are listed in Table 4-19 below:
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Table 4-19: Advantage and Disadvantage – Option 2
Advantages Disadvantages
Suitable with all three excavation
support methods.
Mobilization of grouting equipment at the surface is
required.
Good shaft foundation. Requires verification testing which increases cost and time
of construction.
All three initial support methods
could be installed with
equipment height below the FAA
height restriction of 49 feet.
Commonly used United States CSM equipment for a 34 foot
deep excavation would be approximately 60 feet high.
Procuring low headroom equipment from overseas may be
required.
Option 3 - Excavation support with gravity concrete plug
This system would include the installation of an impermeable excavation support and a sealing
element consisting of concrete gravity plug (refer to Figure 4-40). It is estimated that a 15-foot
thick concrete plug would be required to resist the hydrostatic pressure at the shaft invert. The
system would also require the initial support to extend below the bottom of the plug to ensure the
stability of the excavation before pouring in the concrete plug. It would also require excavation of
the inside of the shaft for the plug installation, which would make this option costly. Therefore, the
impermeable excavation support with gravity concrete plug option is not recommended and is
excluded from further investigation.
Figure 4-40: Gravity Concrete Plug
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The advantages and disadvantages of this system are listed in Table 4-20 below:
Table 4-20: Advantage and Disadvantage – Option 3
Advantages Disadvantages
Suitable with all three excavation
support methods.
Extension of the excavation support system
required.
Excavation of the inside of the shaft for the
plug construction required.
Expensive option overall.
Longer shaft construction duration.
The height of the CSM and sheet piling
equipment required for the installation of
the extended support may encroach on the
FAA height restriction of 49 feet.
Option 4 - Excavation support with jet grouting gravity plug
This system would consist of the installation of an impermeable excavation support system and a
sealing element consisting of a jet grout gravity plug (refer to Figure 4-41). The jet grouting would
be performed from the surface before the shaft excavation begins. The jet grouting technique
injects grout at a high pressure and velocity destroying the soil structure and mixes grout and soil
to form a homogeneous impervious mass.
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Figure 4-41: Gravity Jet Grouting Plug
The advantages and disadvantages of this system are listed in Table 4-21 below.
Table 4-21: Advantages and Disadvantages – Option 4
Advantages Disadvantages
Suitable with all three excavation
support methods.
Mobilization of grouting equipment
at the surface is required.
Provides excellent foundation for
the shaft walls.
Expensive option overall.
All three initial support methods
could be installed with
equipment height below the FAA
height restriction of 49 feet.
Commonly used CSM equipment in
the United States for a 34 foot deep
excavation would be approximately
60 feet high. Procuring low
headroom equipment from overseas
may be required.
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Option 5 - Excavation support with structural concrete invert slab
This system would include the installation of an impermeable excavation support system and a
sealing element consisting of a structural concrete invert slab (refer to Figure 4-42). The structural
concrete invert slab would be reinforced concrete with a minimum thickness of 3 feet.
The installation process requires flooding of the shaft to counterbalance the hydrostatic uplift
pressures. The excavation to the bottom of the impermeable excavation support system would be
performed underwater. Once excavated, the invert slab reinforcement and connections to the
excavation support system would be installed by underwater divers. The concrete would then be
installed using the tremie concrete placement method.
This system is not suitable in combination with sheet piling. The shaft walls would not weigh
enough to counterbalance the uplift forces transferred trough the structural slab.
Figure 4-42: Structural Concrete Slab
The advantages and disadvantages of this system are listed in Table 4-22 below.
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Table 4-22: Advantages and Disadvantages – Option 5
Advantages Disadvantages
Will serve as a mud slab for
construction activities
The system with sheet piling initial support method
would not be sufficient to resist buoyancy.
All three initial support methods
could be installed with equipment
height below the FAA height
restriction of 49 feet.
Difficult to install with all three support methods.
Commonly used CSM equipment in the United States
for a 34 foot deep excavation would be approximately
60 feet high. Procuring low headroom equipment from
overseas may be required.
Impermeable systems comparison cost
Relative comparison costs for the Bair Island Inlet Structure Shaft impermeable system options are
shown in Table 4-23. The costs were developed in 2015 prices. Mark-ups of 25 percent for indirect
costs and 15 percent for overhead and profit are included in the costs. The costs do not include
contingency and escalation. Refer to Appendix A.
Table 4-23: Bair Island Inlet Structure Shaft Initial Support Cost Comparison
Initial Support
Method
Initial Support +
Extended Initial
Support Cost
(Millions)
Initial Support +
Jet Grouting
Plug Cost
(Millions)
Initial Support +
Structural Concrete
Slab Cost
(Millions)
Secant piles $2.8 $2.9 $2.9
CSM $2.5 $2.8 $2.8
Sheet Piling $2.1 $2.3 N/A
4.4.4 Site Conditions The Bair Island Inlet Structure Shaft staging area would be located along the levee road of Inner
Bair Island, north of Whipple Avenue in the City of Redwood City. This site would serve as the
location for TBM retrieval following tunneling from Airport Access Shaft to Bair Island Inlet
Structure Shaft and as the staging area for Bair Island Inlet Structure Shaft construction.
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4.4.4.1 Site Ingress/Egress Access to Inner Bair Island for Bair Island Inlet Structure Shaft construction and TBM retrieval will
be provided from the east end of Whipple Avenue, across Inner Bair Island via an existing unpaved
access road located along the perimeter of Inner Bair Island. The site location and ingress and
egress to/from the site from Highway 101 and surrounding areas are shown in Figure 4-43, below.
Figure 4-43: Bair Island Inlet Structure Shaft Site Ingress and Egress
Specific ingress/egress gate location and access requirements within the site for construction
vehicles is considered in the site staging requirements for the site and is discussed in further detail
below.
4.4.4.2 Existing Site Conditions Inner Bair Island is part of the USFWS Don Edwards San Francisco Bay National Wildlife Refuge
(NWR). The project site is located on San Carlos Airport property and subject to airspace
limitations. The staging area at the Inner Bair Island site is located on a relatively flat peninsula
produced from manmade fill. A levee was recently constructed by the USFWS as part of the Bair
Island Restoration Project (BIRP). This staging area is covered with grass and shrub. The levee is
considered upland habitat. Existing utilities onsite include a 48-inch sanitary sewer force main
(SSFM) located along the western island boundary, within a portion of the BIRP levee. Fiber optic
conduit is located parallel to the existing 48-inch SSFM.
Shaft Construction Site
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4.4.4.3 Staging Area Requirements Due to the flat, gently sloping, and clear topography of the site major, clearing and grading of the
site would not be required prior to construction. The construction area would be stabilized with
filter fabric and a layer of gravel or base rock to provide an all-weather surface for construction.
The staging area perimeter would be fenced with a 6 to 8-foot high security fence to prevent
unauthorized access. A stabilized construction entrance from the public right-of way would be
constructed at the east Whipple Avenue entrance to the unpaved road which provides access to the
northern portion of Inner Bair Island where the construction site would be located. It is anticipated
that biological protection fencing would be required for salt marsh harvest mouse habitat
protection. The onsite mitigation measures required for environmental protection are anticipated
to be included in the CEQA documents for this project and incorporated into the design.
The following items have been considered in developing the construction staging area
requirements for this site:
Shaft Location relative to overall staging area
Location of the existing 48-inch SSFM
Shaft excavation size, configuration and equipment required for the recommended
excavation method
Shaft Excavation Rate: Approximately 4 vertical linear feet (VLF) per day
Excavated Material Storage: 3 Days
Design Vehicle Type: WB-50 (intermediate semi-trailer with 62-foot wheel base)
The staging area can accommodate turnaround of a WH-50 design vehicle. This design vehicle has
similar wheel base and overall dimensions to a standard lowboy tractor trailer combination vehicle
anticipated for in use in delivery of construction material and equipment to the site during shaft
construction. It is anticipated a standard lowboy tractor trailer combination transport vehicle
would also be used for transporting the TBM from the site.
The staging area for this site is shown in Figure 4-44 Approximately 1.5 acres is needed for this
staging area.
4.4.4.4 San Carlos Airport and Federal Aviation Administration Considerations The Inner Bair Island area is located within the San Carlos Airport (SCA) Inner Approach/
Departure Zone. In addition, the staging area for this site also encroaches into the Runway
Protection Zone. Refer to TM No. 1, Appendix A (Exhibit 4-3) for SCA safety zones.
FAA Airspace protection surfaces across the Bair Island Inlet Structure Shaft site staging area are
shown in Figure 4-44.
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C PROPOSED 15'Ø
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25' X 42' BAIR ISLAND RECEIVING PIT (CLEAR)
STAGING AREA
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APPROXIMATE EXTENSION OF FAA PRIMARY SURFACE LINE
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EQUIPMENT/CRANE
WORKING ZONE
NEW 48" DIA
FORCE MAIN
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BAIR ISLAND INLET STRUCTURE SHAFT STAGING AREA - PLAN
APPROX. 1.5 AC
SOIL TREATMENT AREA
EXISTING 48" DIA
FORCE MAIN
Kennedy/Jenks Consultants
SILICON VALLEY CLEAN WATER
TUNNEL PROJECT - TM No. 4
BAIR ISLAND INLET STRUCTURE SHAFT SITE STAGING PLAN
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SITE INGRESS/EGRESS SEE FIGURE 4-43 FOR SITE ACCESS FROM HWY 101
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FAA AIRSPACE PROTECTION SURFACES (SEE NOTES)
K/J 1568063.02 JUNE 2016 FIGURE 4-44
FAA AIRSPACE PROTECTION NOTES:
1. AIRSPACE PROTECTION SURFACE ELEVATIONS ON THIS EXHIBIT ARE EXPRESSED IN
FEET ABOVE MEAN SEA LEVEL (MSL). THE ELEVATION OF SAN CARLOS AIRPORT IS 5
FEET MSL.
2. LOCATIONS WHERE THE GROUND/TERRAIN PENETRATES THE FAR PART 77
AIRSPACE SURFACES ARE APPROXIMATE AND WERE DEVELOPED USING ALUCP
EXHIBIT 4-4 WHICH UTILIZED GROUND ELEVATION CONTOURS PROVIDED BY THE
SAN MATEO COUNTY PLANNING AND BUILDING DEPARTMENT 2014.
3. SOURCE: SAN CARLOS AIRPORT ALUCP, EXHIBIT 4-4 (ESRI, 2014; SAN MATEO
COUNTY PLANNING AND BUILDING DEPARTMENT, 2014; ESA AIRPORTS, 2014).
0
1"=60'
60 10030
20' WIDE SANITARY
SEWER EASEMENT
6557 OR. 480
NOTES:
1. EXISTING 48" FORCEMAIN TO BE ABANDONED AFTER NEW 48" FM IS INSTALLED.
2. EXISTING 48" FORCEMAIN TO REMAIN IN SERVICE AFTER NEW 48" FM IS INSTALLED
AND PROTECTED IN PLACE.
LEGEND
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CONTRACTOR TRAILER
JOB PARKING
CM TRAILER
ENTRY/EXIT GATE
COMPRESSOR
GENERATORS: DUTY AND STANDBY LOCKER ROOM
MATERIAL STORAGE
STORAGE BOXES
EXCAVATED STORAGE (3 DAYS) 40'X125'
WATER TREATMENT FACILITIES
RESTROOM FACILITIES
SHAFT CONSTRUCTION SITE INGRESS/EGRESS. SEE
FIGURE 4-37 FOR SITE INGRESS/EGRESS FROM HWY 101
VEHICLE PATH: WB-50
SEE
NOTE 1
SEE
NOTE 2
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Planning Level Technical Memorandum No. 4
Shaft Construction
The staging area, including soil stabilization area, is primarily located within 54-foot to 88-foot
airspace protection elevation contours. It should be noted these contour elevations represent an
elevation in feet above mean sea level. Based upon the location of these contours across the staging
area, the estimated protection surface elevation above the existing site grade elevation is estimated
to be 49-64 feet above grade near the equipment/crane working area. Refer to Table 4-24 for
additional information. As noted in Section 4.4.3.1, both secant pile and sheet pile shaft
construction methods can meet the FAA height limitations with equipment available in the United
States. Should the sheet pile method be selected, the overall height of the pile driving equipment
would depend upon the overall length of spliced sections (5 feet plus the height of the spliced
sheet). The spliced sheet piling alternative would allow for construction utilizing the sheet piling
method, without encroaching in the protection surface elevation. The longest vertical sheet pile
section which could be accommodated without encroaching in the protection surface elevation
would be approximately 42 feet. The typical equipment utilized for the secant pile method would
be well within the height restrictions for this site.
Table 4-24: Bair Island Inlet Structure Shaft Airspace Protection Height Restrictions
Notes:
(a) Heights are based upon SCA Part 77 Airspace Protection Surfaces, SCA 2015 ALUCP Exhibit 4-4. Height represents
lowest height within the preliminary anticipated crane working zone.
(b) Based upon preliminary site elevations using project vertical datum of NGVD 29 + 100 feet. Grade elevation relative
to MSL was determined by subtracting 100 feet from the preliminary site elevations.
Proposed construction at this location subject to review and approval by the FAA (as administered
by the SCA) and requires an FAA Form 7460-1 be submitted. Specific FAA requirements and
conditions associated with the proposed construction and anticipated crane height encroachment
into the in the FAA jurisdictional areas for the site would be included in the Notice of Determination
by the FAA.
4.4.4.5 Utility Requirements Stabilization and protection of the existing 48-inch sewer force main utilizing surface injection soil
stabilization techniques or another stabilization method, prior to shaft construction and tunneling
approaching the facility at Inner Bair Island will be required. The method for utility stabilization
will be investigated further as the design progresses. Approximate limits for soil stabilization for
protection of the 48-inch force main are shown on Figure 4-44.
The contractor would be required to provide the temporary facilities necessary to provide lighting,
power, water, sanitation services, heating and ventilation need for construction and the
Site
Height Restriction
(Feet Above MSL)(a)
Grade Elevation (Relative to
MSL)(b)
Estimated Height Limit Above Existing Grade
Elevation
Bair Island Inlet Structure Shaft
55 – 72 8 47 - 64
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Planning Level Technical Memorandum No. 4
Shaft Construction
Contractor’s construction trailer at the site. Due to the remote location of the shaft site and
inaccessibility to existing utilities it is anticipated generators would be used for power and portable
sanitation facilities would be utilized.
4.4.4.6 Long Term Operation and Maintenance Requirements Long-term O&M activities are not anticipated to occur at a frequent interval at this location.
Manhole access for infrequent inspection activities would be provided via a 32 to 48-inch manhole
frame and cover and/ or double leaf hatch. Provisions for grit removal/cleanout and air handling
devices such as air limiting device/air valve within a vault are anticipated at this location.
Ultimately, O&M activities and access requirements to final structure(s) will depend upon the
selected connection method.
4.4.5 Construction Considerations 4.4.5.1 Mobilization Mobilization will include all activities for transportation of contractor's personnel, equipment, and
operating supplies to the Bair Island Inlet Structure Shaft staging site necessary for shaft
construction. It will also comprise of installation of field offices, laboratories, fencing, gates, utilities
and other necessary general facilities for the contractor's operations at the site. For more details on
the Bair Island Inlet Structure Shaft staging area, refer to the "Staging Area Requirements" section
above. Mobilization activities will also consist of the contractor obtaining all required insurance,
bonds and permits.
4.4.5.2 Excavated Material Handling Operations All excavated material from the 25-ft x 42-ft Bair Island Inlet Structure Shaft would be handled at
the location. Excavated material that cannot be hauled away during the permitted hauling hours
each day would be stored onsite for hauling on the following work day. A staging area for onsite
storage of approximately three (3) days of excavated material based a shaft excavation rate of 4
VLF/day and average 5-foot high stockpiles would be provided. Onsite storage for excavated
materials stockpiling at this location would encompass an area of approximately 5,000 sf (refer to
Figure 4-44).
Similar to all excavated material for the project, the material would need to be sampled and
analyzed to characterize the soil and determine if there is any soil contamination. Soil
characterization is necessary to confirm the disposal classification for off haul, prior to offsite
disposal or re-use. Acceptance of the soil at a landfill will depend upon overall disposal quantity
and soil characterization and or contamination. Non-contaminated and contaminated material
would be subjected to the profiling requirements of the disposal facility. Ox Mountain Sanitary
Landfill, located in Half Moon Bay, is the closest landfill that accepts this type of construction
excavated material. Ultimately, the Contractor will identify the excavated material disposal
location(s) and/or potential areas for re-use. The hauling requirements noted above for dirt hauling
in the City of Redwood City would apply to this location as well.
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Planning Level Technical Memorandum No. 4
Shaft Construction
A preliminary analysis of the anticipated excavated material handling for this site and anticipated
excavated material quantities for this site is provided below.
Excavated Soil: Approximately 1,470 LCY
Hauling Trucks: 2 average commercial 12.5 loose cubic yard (LCY) dump trucks
Hauling Duration: 3 weeks
Potential ultimate disposal site: Ox Mountain Sanitary Landfill
Average round-trip haul distance: 34 miles
4.4.5.3 Water Treatment and Disposal Although the proposed sealing element at the shaft invert, in conjunction with the impermeable
excavation support, would provide an impervious system to limit the groundwater inflow into the
shaft, it is anticipated that some level of water handling and disposal will be required. The
anticipated water handling quantities for this location during shaft construction will be established
based on the selected impervious system and groundwater information, which will be included in
geotechnical baseline report to be prepared by the PDB.
Similar to the other shaft sites, water handling facilities at this site are anticipated to include sump
pump(s) for pumping groundwater inflow from the shaft excavation to the surface, temporary
containment facilities and control measures such as sediment traps, sediment basin or Baker tank
to remove settleable solids prior to discharge. The need for additional treatment of the water prior
to discharge would depend upon water quality limitations for at the proposed discharge location.
Water could potentially be discharged to one or more of the existing water channels on Inner Bair
Island, similar to the approach utilized during construction of the 48-inch FM receiving shaft
construction on Inner Bair Island. This option will be investigated further by the PDB.
Contaminated water that cannot be treated onsite would require offsite transportation and offsite
disposal of at a properly permitted treatment facility.
4.4.5.4 Shaft Site Restoration and Permanent Facilities The shaft site construction staging area restoration would include site clean-up and re-grading of
the site to restore the original site slopes and drainage patterns. The constructions staging area
would be re-vegetated. An access way would be installed upon completion of this shaft for
entrance into the shaft in the event access would be needed in the future for manhole inspection
and/or access to the tunnel. The access opening would likely include an H-20 traffic rated,
watertight manhole frame and cover and/or double leaf hatch. In addition, provisions for grit
removal (cleanout with surface expression) and air handling provisions (air valve vault with
potential air limiting devise) are anticipated at this location.
This site is located within Federal Emergency Management Agency (FEMA) Flood Zone AE.
According to FEMA definitions, designation as Zone AE indicates the area is subject to inundation
by the 1-percent-annual-chance flood event (100-year floodplain) to an elevation of 10 (NAVD 88)
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Planning Level Technical Memorandum No. 4
Shaft Construction
based on Flood Insurance Rate Map (FIRM) 06081C0188E. FIRM map elevation will need to be
converted to the project datum (NAVD+100) during preliminary design. The manhole opening for
this site would be located 6-12 inches above the flood plain elevation at this location and be
watertight to prevent inflow in the gravity sewer in the event of flooding.
4.4.5.5 Geotechnical Instrumentation and Monitoring The proposed location of the Bair Island Inlet Structure Shaft will be in an open area adjacent to an
unpaved road. There are no structures or pavements within the influence zone around the
perimeter of the shaft. There are underground utilities, including a 48-inch force main in the
vicinity of the shaft excavation. Therefore, the monitoring program proposed for the Bair Island
Inlet Structure Shaft excavation would include instruments to measure lateral ground movements,
settlement of utilities and groundwater fluctuations outside of the shaft excavation. Specifically, the
type of instruments required for the project will include:
Settlement Indicator Points to measure utility settlements.
Subsurface Shallow Settlement Indicators installed adjacent to underground utilities to
measure settlement.
Inclinometers installed adjacent to the initial shaft supports to measure lateral earth
movements as the shaft is excavated.
Control groundwater observation wells installed adjacent to the shaft excavation to
measure groundwater levels.
Prior to commencement of work, a pre-construction survey will be implemented to document the
existing conditions of all underground utilities located entirely or partially within the shaft
excavation influence zone. A 100 to 150-foot limit outside of the shaft perimeter may be considered
as the influence zone. Further evaluation of the influence zone will be performed during design,
taking into consideration the selected initial support method. The pre-construction survey will
document condition of existing utilities to provide a baseline data for evaluating construction
claims.
4.4.6 Recommendations The following criteria were considered in evaluation of the Bair Island Inlet Structure Shaft:
shaft use soil conditions ground water levels shaft construction cost schedule site restrictions such as airspace protection height limits
A comparison table of the three (3) initial support methods evaluated is presented in Table 4-25
below.
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Planning Level Technical Memorandum No. 4
Shaft Construction
Table 4-25: Bair Island Inlet Structure Shaft Initial Support Methods Comparison
From the three initial construction methods evaluated, the secant piles and sheet piling are
considered to be best suited for the Bair Island Inlet Structure Shaft construction. Both methods can
be constructed with equipment below FAA height restrictions. Even though, the secant pile method
is the most expensive option, it could be easily extended below the Upper Layered Sediments to
provide a cut-off for water-bearing sands encountered in this layer. It would allow the construction
the shaft with low construction vibrations considering the fact of close proximity of the shaft to the
existing utilities. It would also permit to construct the shaft with relatively low noise and avoid any
potential problem with noise effecting people across the Pulgas Creek.
The sheet piling would be the least expensive option. It would require installation of jet grouting
plug at the shaft bottom to provide groundwater cut-off. However, this option could pose a noise
problem for the buildings across the Pulgas Creek and the vibrations may have negative effect on
the existing utilities. Noise attenuation measures may have to be employed. One option would be to
install fencing with noise absorbing blankets. These two support methods will be further evaluated
in preliminary design phase of the project.
Secant Piles CSM Sheet Piling
Requires excavation of secant piles, concrete placement, installation of vertical beams and internal bracing. Longest duration.
Requires mixing of soil with cement, installation of vertical beams and internal bracing. Duration relatively similar to secant piles.
Requires only installation of sheet piling and internal bracing. Shortest duration.
Relatively impermeable system.
Relatively impermeable system.
The steel sheet piling will permit minor flows into the shaft. Flows are anticipated to be handled with pumping within the shaft.
Most expensive option. Relatively similar cost to the secant pile option.
Least expensive option.
Can be installed with equipment meeting the FAA height restriction of 49 feet.
Can be installed with equipment meeting the FAA height restriction of 49 feet. However, the equipment has not been used in the United States yet and procuring it may impact the cost and schedule of the shaft construction.
Can be installed with equipment meeting the FAA height restriction of 49 feet except for Option 1 (extended excavation support). Approximately 60 feet of headroom is required to drive the sheet piling in one piece. The sheet piling could be installed in sections; however, that would increase the cost and construction duration.
Low construction site noise and vibration level.
Low construction site noise and vibration level.
Significantly higher level of noise and vibrations than the other options. Noise during installation may pose a problem for the buildings across Pulgas Creek. Vibrations may negatively affect the existing force main.
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Planning Level Technical Memorandum No. 4
Shaft Construction
4.5 Construction Schedule The SVCW Conveyance System Planning Group is maintaining an overall schedule (Version 12 at
the time of preparation of this TM) for design and construction of the conveyance system
improvements. Anticipated dates for construction are not included herein as these dates are subject
to significant change as the project develops and policy decisions are made that affect the schedule.
Within the overall schedule, the Airport Access Shaft and RLS/Flow Splitter Shafts are anticipated
to be constructed concurrently so that the Flow Splitter Shaft will be available for TBM retrieval
once the tunneling activity from Airport Access Shaft to the RLS/Flow Splitter Shaft is completed.
The construction sequencing of the Bair Island Inlet Structure Shaft will be such that it is complete
and available for TBM retrieval in advance of the tunneling activity from the Airport Access Shaft
reaching Inner Bair Island. The San Carlos Drop Shaft is offset from the tunnel, such that an adit
connection to the tunnel is required. Soil stabilization will be necessary at the San Carlos Drop
Shaft location and must be completed prior to tunnel activity reaching this site.
Anticipated shaft construction durations, as shown in the Program Schedule (Version 12) are
summarized in Table 4-26, below.
Table 4-26: Shaft Construction Durations
Shaft Construction Duration (Working Days)
RLS /Flow Splitter 140
Airport Access 207
San Carlos Drop 250
Bair Island Inlet Structure 107
The PDB will produce and maintain the overall schedule for the Gravity Pipeline, recording
refinements to the durations and sequence of activities as more details are developed.
Section 5: Summary and Recommendations
This section summarizes the findings and recommendations of TM No. 4. Further details can be
found in the respective sections of the TM. Table 5-1 presents the recommended shaft
configuration and dimensions. Based on a review of the geology at the shaft sites, conventional soil
excavation techniques such as a crane and a clamshell bucket or an excavator can be utilized to
excavate the materials within the shafts.
Table 5-1: Shaft Structure Configuration and Dimensions
Shaft Structure Configuration Dimensions
RLS Shaft(a) Figure “8” (combined with Flow 28.5 to 52 feet in diameter x 84-ft
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Planning Level Technical Memorandum No. 4
Shaft Construction
Splitter Shaft) or separate shaft deep
Flow Splitter
Shaft(a)
Figure “8” (combined with RLS
Shaft) or separate shaft
25 to 32 feet in diameter x 68-ft
deep
Airport Access
Shaft Circular 35-ft in diameter x 52-ft deep
San Carlos Drop
Shaft Circular
15 to 20 feet in diameter x 52-feet
deep
Bair Island Inlet
Structure Shaft Rectangular
25-ft x 42-ft plan dimension x 27-
feet deep
Notes:
(a) Final configuration for RLS and Flow Splitter Shafts will be determined by the PDB.
Table 5-2 summarizes the recommended shaft support method for each of the four (4) sites and
the primary benefits of the recommended method(s).
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Planning Level Technical Memorandum No. 4
Shaft Construction
Table 5-2: Shaft Support Method Recommendations
Shaft Recommended Method Comments
RLS Slurry Walls or Caisson(a)
Greater achievable construction depths as
compared to secant piles which would be
reaching the practical limit of installation at the
proposed shaft depths.
Less infiltration anticipated with the
recommended methods as compared to secant
piles.
Provide more robust support system for the
Receiving Lift Station structure than secant piles.
Refer to Tables 4-8, 4-9 and 4-10 for cost and
methods comparison.
Airport
Access Shaft Secant Piles
Can be constructed with low headroom
restrictions.
Commonly used system.
Low vibration and noise during installation.
Rigid system as compared to sheet piling
Economical.
San Carlos
Drop Shaft Caisson
Can be constructed with low headroom
restrictions of 21 feet.
Low noise and vibrations during installation.
Best suits the site constraints.
Bair Island
Inlet
Structure
Shaft
Secant Piles or Sheet
Piling(b)
Can be constructed with low headroom
restrictions of 49 feet with equipment available
in the United States.
Refer to Tables 4-23 and Table 4-25 for cost
and methods comparison.
Notes:
(a) Recommendation for initial support system will be made by the PDB once the structure configuration for RLS and
Flow Splitter Shafts is selected and further evaluation is performed.
(b) Recommendation for the initial support system will be made by the PDB following further evaluation of the two
options.
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Planning Level Technical Memorandum No. 4
Shaft Construction
Additional evaluation of secant piles and sheet piling shaft support methods for the Bair Island Inlet
Structure Shaft is recommended during primary design. In addition, further evaluation of the
following two shaft configurations and initial support methods for the RLS and Flow Splitter Shaft
during preliminary design is also recommended. Final selection of the initial support system for RLS
is dependent upon on the final shaft configuration and type of corrosion protection layer selected.
Figure “8” configuration or two shaft configuration
Slurry Walls or Caisson
Table 5-3 summarizes the recommended staging area sizes at each shaft site.
Table 5-3: Shaft Staging Area Sizes
Shaft Site Proposed Area
(Acres)
RLS
RLS and Flow Splitter Shafts 2.5
Flow Splitter Shaft (for TBM
retrieval purposes) 0.4
Airport Access 6.5
San Carlos Drop 0.6
Bair Island Inlet Structure 1.5
THIS PAGE INTENTIONALLY BLANK
AppendixA
General Info:
Option 1 Option 4 Option 5
Shaft diameter - ID FT 32.0 - 52.0 32.0 - 52.0 32.0 - 52.0
Shaft depth FT 67.5 - 83.5 67.5 - 83.5 67.5 - 83.5
Wall embedment FT 33.5 - 17.5 5.0 5.0
Depth of panels FT 101.0 72.5 - 88.5 80.5 - 96.5
Wall thickness FT 3.0 3.0 3.0
Thickness of bottom slab FT 1.0(1) 1.0(1) 8.0(2)
Shaft penetration by tunnels Ea 1 1 1
Option 1: Extended Initial Support
Option 4: Jet Grouting Plug
Option 5: 8'-0" Structural Concrete Slab
Option 1 Option 4 Option 5
0. Jet Grouting Plug - 32'-6" Thick (Flow Splitter Shaft), 16'-6" Thick (RLS Shaft) -$ 950,000$ -$
1. Set Guides 350,000$ 350,000$ 350,000$
2. Excavate Panels 870,000$ 710,000$ 780,000$
3. Slurry Cleaning and Desanding 150,000$ 120,000$ 140,000$
4. Set up and Install Rebar Cages 880,000$ 880,000$ 970,000$
5. Slurry Walls - Place Tremie Concrete 710,000$ 620,000$ 660,000$
6. Excavate Inside Shaft 570,000$ 570,000$ 600,000$
7. Bottom Slab 80,000$ 80,000$ 380,000$
8. Tunnel Breakout 250,000$ 250,000$ 250,000$
TOTAL DIRECT COST 3,860,000$ 4,530,000$ 4,130,000$
Indirect Cost 25% 965,000$ 1,132,500$ 1,032,500$
4,825,000$ 5,662,500$ 5,162,500$
Overhead and Profit 15% 723,750$ 849,375$ 774,375$
5,548,750$ 6,511,875$ 5,936,875$
TOTAL BID PRICE 5,548,750$ 6,511,875$ 5,936,875$
TOTAL COST 5,500,000$ 6,500,000$ 5,900,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 8'-0" thick Structural Concrete Slab.(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.(4) Sales tax of 9% is applied to the cost of materials in the estimate.
(5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
RLS - Figure "8" Configuration
Slurry Walls
Shaft Initial Support Cost Summary
RLS COST - Figure Eight Configuration(3)
(Flow Splitter Shaft - RLS Shaft)
June 9th, 2016
General Info:
Option 1 Option 4 Option 5
Shaft diameter - ID FT 32.0 - 52.0 32.0 - 52.0 32.0 - 52.0
Shaft depth FT 67.5 - 83.5 67.5 - 83.5 67.5 - 83.5
Wall embedment FT 33.5 - 17.5 5.0 5.0
Pile depth FT 101.0 72.5 - 88.5 80.5 - 96.5
Pile diameter FT 4.0 4.0 4.0
Thickness of bottom slab FT 1.0(1) 1.0(1) 8.0(2)
Shaft penetration by tunnels Ea 1 1 1
Option 1: Extended Initial Support
Option 4: Jet Grouting Plug
Option 5: 8'-0" Structural Concrete Slab
Option 1 Option 4 Option 5
0. Jet Grouting Plug - 32'-6" Thick (Flow Splitter Shaft), 16'-6" Thick (RLS Shaft) -$ 950,000$ -$
1. Set Guides 310,000$ 310,000$ 310,000$
2. Excavate and Install Secant Piles 2,280,000$ 1,870,000$ 2,070,000$
3. Excavate Inside Shaft 570,000$ 570,000$ 600,000$
4. Bottom Slab 80,000$ 80,000$ 730,000$
5. Tunnel Breakout 250,000$ 250,000$ 250,000$
TOTAL DIRECT COST 3,490,000$ 4,030,000$ 3,960,000$
Indirect Cost 25% 872,500$ 1,007,500$ 990,000$
4,362,500$ 5,037,500$ 4,950,000$
Overhead and Profit 15% 654,375$ 755,625$ 742,500$
5,016,875$ 5,793,125$ 5,692,500$
TOTAL BID PRICE 5,016,875$ 5,793,125$ 5,692,500$
TOTAL COST 5,000,000$ 5,800,000$ 5,700,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 8'-0" thick Structural Concrete Slab.(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.(4) Sales tax of 9% is applied to the cost of materials in the estimate. (5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
RLS - Figure "8" Configuration
Secant Piles
Shaft Initial Support Cost Summary
RLS COST - Figure Eight Configuration(3)
(Flow Splitter Shaft - RLS Shaft)
June 9th, 2016
General Info:
Option 4 Option 5 Option 6
Shaft diameter - ID FT 32.0 - 52.0 32.0 - 52.0 32.0 - 52.0
Shaft depth FT 67.5 - 83.5 67.5 - 83.5 67.5 - 83.5
Wall embedment FT 5.0 5.0 5.0
Wall depth FT 73.5 - 89.5 80.5 - 96.5 77.0 - 93.0
Wall thickness FT 3.0 3.0 3.0
Thickness of bottom slab FT 1.0(1) 8.0(2) 4.5(3)
Shaft penetration by tunnels Ea 1 1 1
Option 4: Jet Grouting Plug
Option 5: 8'-0" Structural Concrete Slab
Option 6: Jet Grouting Water Cut-off Curtain
Option 4 Option 5 Option 6
0. Jet Grouting Plug - 32'-6" Thick (Flow Splitter Shaft), 16'-6" Thick (RLS Shaft) 950,000$ -$ -$
1. Concrete Collar 200,000$ 200,000$ 370,000$
2. Excavate Piles 190,000$ 190,000$ 210,000$
3. Install Piles - Place Tremie Concrete 170,000$ 170,000$ 170,000$
4. Excavate Inside Shaft 570,000$ 600,000$ 580,000$
5. Bottom Slab 140,000$ 380,000$ 260,000$
6. Tunnel Breakout 250,000$ 250,000$ 250,000$
7. Caisson Walls 2,420,000$ 2,640,000$ 2,540,000$
8. Jet Grouting Water Cut-off Curtain -$ -$ 1,290,000$
TOTAL DIRECT COST 4,890,000$ 4,430,000$ 5,670,000$
Indirect Cost 25% 1,222,500$ 1,107,500$ 1,417,500$
6,112,500$ 5,537,500$ 7,087,500$
Overhead and Profit 15% 916,875$ 830,625$ 1,063,125$
7,029,375$ 6,368,125$ 8,150,625$
TOTAL BID PRICE 7,029,375$ 6,368,125$ 8,150,625$
TOTAL COST 7,000,000$ 6,400,000$ 8,200,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 8'-0" thick Structural Slab.(3) 4'-6" thick Structural Slab.(4) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.(5) Sales tax of 9% is applied to the cost of materials in the estimate. (6) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that thisis not a final estimate.
RLS - Figure "8" Configuration
Caisson
Shaft Initial Support Cost Summary
RLS COST - Figure Eight Configuration(4)
(Flow Splitter Shaft - RLS Shaft)
June 9th, 2016
General Info:
Option 1 Option 4 Option 5
Shaft diameter - ID FT 25.0 - 28.5 25.0 - 28.5 25.0 - 28.5
Shaft depth FT 67.5 - 83.5 67.5 - 83.5 67.5 - 83.5
Wall embedment FT 33.5 - 17.5 5.0 5.0
Depth of panels FT 101.0 72.5 - 88.5 77.0 - 93.0
Wall thickness FT 3.0 3.0 3.0
Thickness of bottom slab FT 1.0(1) 1.0(1) 4.5(2)
Option 1: Extended Initial Support
Option 4: Jet Grouting Plug
Option 5: 4'-6" Structural Slab
Option 1 Option 4 Option 5
0. Jet Grouting Plug - 32'-6" Thick (Flow Splitter Shaft), 16'-6" Thick (RLS Shaft) -$ 420,000$ -$
1. Set Guides 290,000$ 290,000$ 290,000$
2. Excavate Panels 610,000$ 510,000$ 540,000$
3. Slurry Cleaning and Desanding 110,000$ 80,000$ 100,000$
4. Set up and Install Rebar Cages 580,000$ 580,000$ 610,000$
5. Slurry Walls - Place Tremie Concrete 470,000$ 400,000$ 410,000$
6. Excavate Inside Shaft 220,000$ 220,000$ 230,000$
7. Bottom Slab 70,000$ 70,000$ 160,000$
8. Tunnel Breakout 250,000$ 250,000$ 250,000$
9. Soil Improvement: Jet Grouting at Connection Tunnel 800,000$ 590,000$ 640,000$
10. Connection Tunnel 620,000$ 620,000$ 620,000$
TOTAL DIRECT COST 4,020,000$ 4,030,000$ 3,850,000$
Indirect Cost 25% 1,005,000$ 1,007,500$ 962,500$
5,025,000$ 5,037,500$ 4,812,500$
Overhead and Profit 15% 753,750$ 755,625$ 721,875$
5,778,750$ 5,793,125$ 5,534,375$
TOTAL BID PRICE 5,778,750$ 5,793,125$ 5,534,375$
TOTAL COST 5,800,000$ 5,800,000$ 5,500,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 4'-6" thick Structural Slab.(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.(4) Sales tax of 9% is applied to the cost of materials in the estimate.
(5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
RLS - Two Separate Shaft with Connection Tunnel
Slurry Walls
Shaft Initial Support Cost Summary
RLS COST - Two Separate Shaft with Connection Tunnel(3)
(Flow Splitter Shaft - RLS Shaft)
June 9th, 2016
General Info:
Option 1 Option 4 Option 5
Shaft diameter - ID FT 25.0 - 28.5 25.0 - 28.5 25.0 - 28.5
Shaft depth FT 67.5 - 83.5 67.5 - 83.5 67.5 - 83.5
Wall embedment FT 33.5 - 17.5 5.0 5.0
Pile depth FT 101.0 72.5 - 88.5 77.0 - 93.0
Pile diameter FT 3.5 3.5 3.5
Thickness of bottom slab FT 1.0(1) 1.0(1) 4.5(2)
Option 1: Extended Initial Support
Option 4: Jet Grouting Plug
Option 5: 4'-6" Structural Slab
Option 1 Option 4 Option 5
0. Jet Grouting Plug - 32'-6" Thick (Flow Splitter Shaft), 16'-6" Thick (RLS Shaft) -$ 420,000$ -$
1. Set Guides 250,000$ 250,000$ 250,000$
2. Excavate and Install Secant Piles 1,470,000$ 1,210,000$ 1,220,000$
3. Excavate Inside Shaft 220,000$ 220,000$ 230,000$
4. Bottom Slab 70,000$ 70,000$ 510,000$
5. Tunnel Breakout 250,000$ 250,000$ 250,000$
6. Soil Improvement: Jet Grouting at Connection Tunnel 800,000$ 590,000$ 640,000$
7. Connection Tunnel 620,000$ 620,000$ 620,000$
TOTAL DIRECT COST 3,680,000$ 3,630,000$ 3,720,000$
Indirect Cost 25% 920,000$ 907,500$ 930,000$
4,600,000$ 4,537,500$ 4,650,000$
Overhead and Profit 15% 690,000$ 680,625$ 697,500$
5,290,000$ 5,218,125$ 5,347,500$
TOTAL BID PRICE 5,290,000$ 5,218,125$ 5,347,500$
TOTAL COST 5,300,000$ 5,200,000$ 5,300,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 4'-6" thick Structural Slab.(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.(4) Sales tax of 9% is applied to the cost of materials in the estimate. (5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
RLS - Two Separate Shaft with Connection Tunnel
Secant Piles
Shaft Initial Support Cost Summary
RLS COST - Two Separate Shaft with Connection Tunnel(3)
(Flow Splitter Shaft - RLS Shaft)
June 9th, 2016
General Info:
Option 4 Option 5 Option 6
Shaft diameter - ID FT 25.0 - 28.5 25.0 - 28.5 25.0 - 28.5
Shaft depth FT 67.5 - 83.5 67.5 - 83.5 67.5 - 83.5
Wall embedment FT 5.0 5.0 5.0
Wall depth FT 72.5 - 88.5 77.0 - 93.0 77.0 - 93.0
Wall thickness FT 3.0 3.0 3.0
Thickness of bottom slab FT 1.0(1) 4.5(2) 4.5(2)
Option 4: Jet Grouting Plug
Option 5: 8'-0" Structural Concrete Slab
Option 6: Jet Grouting Water Cut-off Curtain
Option 4 Option 5 Option 6
0. Jet Grouting Plug - 32'-6" Thick (Flow Splitter Shaft), 16'-6" Thick (RLS Shaft) 420,000$ -$ -$
1. Concrete Collar 310,000$ 310,000$ 490,000$
2. Excavate Piles 240,000$ 240,000$ 260,000$
3. Install Piles - Place Tremie Concrete 200,000$ 200,000$ 200,000$
4. Excavate Inside Shaft 220,000$ 230,000$ 230,000$
5. Bottom Slab 130,000$ 160,000$ 160,000$
6. Caisson Wall 1,760,000$ 1,830,000$ 1,830,000$
7. Tunnel Breakout 250,000$ 250,000$ 250,000$
8. Soil Improvement: Jet Grouting at Connection Tunnel 590,000$ 640,000$ 640,000$
9. Connection Tunnel 620,000$ 620,000$ 620,000$
10. Jet Grouting Water Cut-off Curtain -$ -$ 740,000$
TOTAL DIRECT COST 4,740,000$ 4,480,000$ 5,420,000$
Indirect Cost 25% 1,185,000$ 1,120,000$ 1,355,000$
5,925,000$ 5,600,000$ 6,775,000$
Overhead and Profit 15% 888,750$ 840,000$ 1,016,250$
6,813,750$ 6,440,000$ 7,791,250$
TOTAL BID PRICE 6,813,750$ 6,440,000$ 7,791,250$
TOTAL COST 6,800,000$ 6,400,000$ 7,800,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 4'-6" thick Structural Slab.(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.(4) Sales tax of 9% is applied to the cost of materials in the estimate. (5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that thisis not a final estimate.
RLS - Two Separate Shaft with Connection Tunnel
Caisson
Shaft Initial Support Cost Summary
RLS COST - Two Separate Shaft with Connection Tunnel(3)
(Flow Splitter Shaft - RLS Shaft)
June 9th, 2016
General Info:
Slurry Walls Secant Piles CSM(1) Sheet Piles
Shaft diameter - ID FT 35 35 35 35
Shaft depth FT 52 52 52 52
Wall embedment FT 5 5 5 5
Depth of panels/piles FT 57 57 57 57
Wall thickness FT 2.50 3.75 5.00 0.031
Thickness of bottom slab FT 1.0 1.0 1.0 1.0
Slurry Walls Secant Piles CSM Sheet Piles
1. Set Guide Wall 140,000$ 140,000$ 100,000$ -$
2. Excavate and Install Temporary Support 740,000$ 560,000$ 630,000$ 550,000$
3. Excavate Inside Shaft 130,000$ 130,000$ 130,000$ 130,000$
4. Bottom Slab - 1'-0" Thick Mud Slab 60,000$ 60,000$ 60,000$ 60,000$
5. Tunnel Breakout (2) 200,000$ 200,000$ 200,000$ 200,000$
6. Shaft Interior 730,000$ 730,000$ 730,000$ 730,000$
TOTAL DIRECT COST 2,000,000$ 1,820,000$ 1,850,000$ 1,670,000$
Indirect Cost 25% 500,000$ 455,000$ 462,500$ 417,500$
2,500,000$ 2,275,000$ 2,312,500$ 2,087,500$
Overhead and Profit 15% 375,000$ 341,250$ 346,875$ 313,125$
2,875,000$ 2,616,250$ 2,659,375$ 2,400,625$
TOTAL BID PRICE 2,875,000$ 2,616,250$ 2,659,375$ 2,400,625$
TOTAL COST 2,900,000$ 2,600,000$ 2,700,000$ 2,400,000$
Notes
(3) Sales tax of 9% is applied to the cost of materials in the estimate. (4) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
AIRPORT ACCESS SHAFT
Slurry Walls - Secant Piles - Cutter Soil Mixing (CSM) - Sheet Piles
Shaft Initial Support Cost Summary
AIRPORT ACCESS SHAFT COST(2)
(2) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.
(1) Double CSM Ring Configuration.
June 9th, 2016
General Info:
CSM Caisson
Shaft diameter - ID FT 20 20
Shaft depth FT 52 52
Wall embedment FT 2 2
Wall depth FT 54 54
Wall thickness FT 1.0(1) 1.5(2)
Thickness of bottom slab FT 1.0 1.0
CSM Caisson
1. Concrete Collar -$ 160,000$
2. Soil Improvement: Cutter Soil Mixing (CSM) - Jet Grouting (Caisson) - 35'-0" Thick 550,000$ 310,000$
3. Excavate Inside Shaft 60,000$ 60,000$
4. Bottom Slab - 1'-0" Thick Mud Slab 20,000$ 20,000$
5. Tunnel Breakout 250,000$ 250,000$
6. Shotcrete Lining 160,000$ -$
7. Caisson Walls -$ 480,000$
8. Shaft Interior 220,000$ 220,000$
9. Adit 290,000$ 290,000$
TOTAL DIRECT COST 1,550,000$ 1,790,000$
Indirect Cost 25% 387,500$ 447,500$
1,937,500$ 2,237,500$
Overhead and Profit 15% 290,625$ 335,625$
2,228,125$ 2,573,125$
TOTAL BID PRICE 2,228,125$ 2,573,125$
TOTAL COST 2,200,000$ 2,600,000$
Notes
(4) Sales tax of 9% is applied to the cost of materials in the estimate. (5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that thisis not a final estimate.
(1) 1'-0" thick Shotcrete Lining.(2) 1'-6" thick Caisson Wall.
SAN CARLOS DROP SHAFT
Cutter Soil Mixing (CSM) - Caisson
Shaft Initial Support Cost Summary
SAN CARLOS DROP SHAFT COST(5)
(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.
June 9th, 2016
General Info:
Option 1 Option 2 Option 3
Inside shaft length FT 42 42 42
Inside shaft width FT 25 25 25
Shaft depth FT 27 27 27
Wall embedment FT 25 7 7
Depth of piles FT 52 34 37
Pile diameter FT 2.5 2.5 2.5
Thickness of bottom slab FT 1.0(1) 1.0(1) 3.0(2)
Shaft penetration by tunnels Ea 1 1 1
Option 1: Extended Initial Support
Option 2: Jet Grouting Plug
Option 3: 3'-0" Structural Concrete Slab
Option 1 Option 2 Option 3
0. Jet Grouting Plug - 15'-0" Thick -$ 240,000$ -$
1. Set Guide Wall 170,000$ 170,000$ 170,000$
2. Excavate and Install Secant Piles 750,000$ 600,000$ 610,000$
3. Install Bracing System 150,000$ 150,000$ 150,000$
4. Excavate Inside Shaft 80,000$ 80,000$ 90,000$
5. Bottom Slab 40,000$ 40,000$ 240,000$
6. Tunnel Breakout 250,000$ 250,000$ 250,000$
7. Shaft Interior 500,000$ 500,000$ 500,000$
TOTAL DIRECT COST 1,940,000$ 2,030,000$ 2,010,000$
Indirect Cost 25% 485,000$ 507,500$ 502,500$
2,425,000$ 2,537,500$ 2,512,500$
Overhead and Profit 15% 363,750$ 380,625$ 376,875$
2,788,750$ 2,918,125$ 2,889,375$
TOTAL BID PRICE 2,788,750$ 2,918,125$ 2,889,375$
TOTAL COST 2,800,000$ 2,900,000$ 2,900,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 3'-0" thick Structural Concrete Slab.
(4) Sales tax of 9% is applied to the cost of materials in the estimate. (5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
BAIR ISLAND INLET STRUCTURE SHAFT
Secant Piles
Shaft Initial Support Cost Summary
BAIR ISLAND INLET STRUCTURE SHAFT COST(3)
(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.
June 9th, 2016
General Info:
Option 1 Option 2 Option 3
Inside shaft length FT 42 42 42
Inside shaft width FT 25 25 25
Shaft depth FT 27 27 27
Wall embedment FT 25 7 7
Depth of panels FT 52 34 37
Wall thickness FT 2.0 2.0 2.0
Thickness of bottom slab FT 1.0(1) 1.0(1) 3.0(2)
Shaft penetration by tunnels Ea 1 1 1
Option 1: Extended Initial Support
Option 2: Jet Grouting Plug
Option 3: 3'-0" Structural Concrete Slab
Option 1 Option 2 Option 3
0. Jet Grouting Plug - 15'-0" Thick -$ 240,000$ -$
1. Guide Trench 150,000$ 150,000$ 150,000$
2. CSM Wall Panels: Cutting and Mixing 600,000$ 570,000$ 570,000$
3. Install Bracing System 150,000$ 150,000$ 150,000$
4. Excavate Inside Shaft 80,000$ 80,000$ 90,000$
5. Bottom Slab 40,000$ 40,000$ 240,000$
6. Tunnel Breakout 250,000$ 250,000$ 250,000$
7. Shaft Interior 500,000$ 500,000$ 500,000$
TOTAL DIRECT COST 1,770,000$ 1,980,000$ 1,950,000$
Indirect Cost 25% 442,500$ 495,000$ 487,500$
2,212,500$ 2,475,000$ 2,437,500$
Overhead and Profit 15% 331,875$ 371,250$ 365,625$
2,544,375$ 2,846,250$ 2,803,125$
TOTAL BID PRICE 2,544,375$ 2,846,250$ 2,803,125$
TOTAL COST 2,500,000$ 2,800,000$ 2,800,000$
Notes
(1) 1'-0" thick Mud Slab.(2) 3'-0" thick Structural Concrete Slab.
(4) Sales tax of 9% is applied to the cost of materials in the estimate.
(5) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
BAIR ISLAND INLET STRUCTURE SHAFT
Cutter Soil Mixing
Shaft Initial Support Cost Summary
BAIR ISLAND INLET STRUCTURE SHAFT COST(3)
(3) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.
June 9th, 2016
General Info:
Option 1 Option 2
Inside shaft length FT 42 42
Inside shaft width FT 25 25
Shaft depth FT 27 27
Wall embedment FT 25 7
Depth of piles FT 52 34
Thickness of bottom slab FT 1.0 1.0
Shaft penetration by tunnels Ea 1 1
Option 1: Extended Initial Support
Option 2: Jet Grouting Plug
Option 1 Option 2
0. Jet Grouting Plug - 15'-0" Thick -$ 240,000$
1. Steel Sheet Piles Installation 410,000$ 300,000$
2. Install Bracing System 150,000$ 150,000$
3. Excavate Inside Shaft 80,000$ 80,000$
4. Bottom Slab - 1'-0" Thick Mud Slab 40,000$ 40,000$
5. Tunnel Breakout 250,000$ 250,000$
6. Shaft Interior 500,000$ 500,000$
TOTAL DIRECT COST 1,430,000$ 1,560,000$
Indirect Cost 25% 357,500$ 390,000$
1,787,500$ 1,950,000$
Overhead and Profit 15% 268,125$ 292,500$
2,055,625$ 2,242,500$
TOTAL BID PRICE 2,055,625$ 2,242,500$
TOTAL COST 2,100,000$ 2,300,000$
Notes(1) The estimate DOES NOT INCLUDE bond and insurance, builders risk insurance, comprehensive general liability insurance, contingency and soft costs.(2) Sales tax of 9% is applied to the cost of materials in the estimate. (3) We have utilized our tunneling experience, local labor rates and benefits and current prices for each listed items. No design has been conducted at this point. Therefore, it should be noted that this isnot a final estimate.
BAIR ISLAND INLET STRUCTURE SHAFT
Sheet Piles
Shaft Initial Support Cost Summary
BAIR ISLAND INLET STRUCTURE SHAFT COST(1)
June 9th, 2016
AppendixB
REGULATIONS
of
Silicon Valley Clean Water
1990 Regulations 1991 Amendments 2000 Amendments 2005 Amendments
TABLE OF CONTENTS
ARTICLE I. GENERAL .............................................................................................................................. 1
SPECIFIC DEFINITIONS ........................................................................................................................ 1
ARTICLE II. PROHIBITIONS ................................................................................................................... 8
GENERAL PROHIBITIONS .................................................................................................................... 8
SPECIFIC SOURCES PROHIBITED .................................................................................................... 10
WASTEWATER STRENGTH LIMITATIONS .................................................................................... 10
SPECIFIC WASTES PROHIBITED ...................................................................................................... 11
SPECIFIC USER LIMITATIONS .......................................................................................................... 12
ARTICLE III. WASTEWATER VOLUME DETERMINATION ............................................................ 12
METERING ............................................................................................................................................ 13
EXCEPTIONS - ESTIMATED VOLUME............................................................................................. 13
ARTICLE IV. REPORTS, PERMITS AND ADMINISTRATION .......................................................... 14
REPORTS ............................................................................................................................................... 14
MANDATORY WASTEWATER DISCHARGE PERMITS ................................................................ 16
DISCRETIONARY WASTEWATER DISCHARGE PERMITS .......................................................... 16
APPLICATIONS FOR MANDATORY WASTEWATER DISCHARGE PERMITS .......................... 17
APPLICATIONS FOR DISCRETIONARY WASTEWATER DISCHARGE PERMITS .................... 18
PERMIT CONDITIONS ......................................................................................................................... 19
DURATION OF PERMITS .................................................................................................................... 20
NON-ASSIGNABILITY......................................................................................................................... 21
MONITORING FACILITIES ................................................................................................................. 21
INSPECTION AND SAMPLING ........................................................................................................... 22
PRETREATMENT ................................................................................................................................. 23
ACCIDENTAL DISCHARGES ............................................................................................................. 24
PUBLIC INFORMATION ...................................................................................................................... 25
SPECIAL AGREEMENTS ..................................................................................................................... 25
ARTICLE V. CHARGES AND FEES ...................................................................................................... 25
USER CLASSIFICATIONS, ADMINISTRATION ............................................................................... 25
SPECIFIC CHARGES AND FEES ........................................................................................................ 26
COMBINED FEES AND CHARGES .................................................................................................... 26
ARTICLE VI. ENFORCEMENT .............................................................................................................. 27
RESPONSIBILITY ................................................................................................................................. 27
UNAUTHORIZED DISCHARGES ....................................................................................................... 27
CEASE AND DESIST ORDERS ........................................................................................................... 28
TIME SCHEDULES ............................................................................................................................... 28
EMERGENCY CORRECTIONS ........................................................................................................... 29
DAMAGES TO SEWERAGE FACILITIES .......................................................................................... 29
EMERGENCY TERMINATION OF SERVICE .................................................................................... 29
PERMIT REVOCATION ....................................................................................................................... 30
NOTICE OF VIOLATION ..................................................................................................................... 31
ENFORCEMENT HEARING ................................................................................................................ 31
APPEALS ................................................................................................................................................ 33
PUBLIC NUISANCE.............................................................................................................................. 34
CIVIL ASSESSMENTS.......................................................................................................................... 34
AGENCY'S REGULATIONS ................................................................................................................ 35
AUTHORITY'S DISCRETION .............................................................................................................. 35
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page 1
REGULATIONS OF THE SILICON VALLEY CLEAN WATER
ESTABLISHING UNIFORM STANDARDS, CONDITIONS AND
REQUIREMENTS FOR THE USE OF THE SANITARY SEWERAGE
FACILITIES OF SAID AUTHORITY AND ITS MEMBER AGENCIES
ARTICLE I. GENERAL.
SECTION 1.1. The purpose of these regulations is to establish standards, conditions and
requirements relating to the use of the sanitary sewerage facilities of the Silicon Valley Clean Water and
its member agencies. In adopting these regulations the Commission of Silicon Valley Clean Water
intends that, pursuant to the Joint Exercise of Powers Agreement hereinafter defined, the member
agencies of the Authority shall likewise adopt these regulations as uniform wastewater ordinances
enforceable throughout their respective jurisdictions. It is further the purpose of these regulations to
enable this Authority and the member agencies thereof to comply with and meet applicable laws,
regulations, standards and conditions established by federal and state law, or by agencies thereof in the
implementation of such law. The Commission of Silicon Valley Clean Water hereby finds and declares
that the health, safety and welfare of the people within its service area, and within the respective service
areas of the member agencies of this Authority, require the enactment and uniform implementation of
these regulations throughout said service areas. SECTION 1.2. TECHNICAL TERMINOLOGY.
Words, phrases, or terms not specifically defined herein, and having a technical or specialized meaning
shall be defined as set forth in the latest edition of "Standard Methods for the Examination of Water and
Wastewater", published by the American Public Health Association, the American Water Works
Association, and the Water Pollution Control Federation.
Waste constituents and characteristics, and measurements thereof, as used herein shall have the
meanings and descriptions ascribed thereto in the aforesaid publication, or as established by federal or
state regulatory agencies.
SECTION 1.3.0. SPECIFIC DEFINITIONS. The following words or phrases wherever used in
these regulations shall have the meanings respectively ascribed thereto.
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SECTION 1.3.1. ACT or the ACT. The Federal Water Pollution Control Act as amended by the
Federal Water Pollution Control Act Amendments of 1972 (Public Law 92-500), and as amended from
time to time thereafter (33 U.S.C. §1251 et seq.), commonly referred to as the Clean Water Act.
SECTION 1.3.2. AGENCY or AGENCIES. The member agencies of the Silicon Valley Clean
Water, to wit: the Cities of Belmont, Redwood City, and San Carlos, municipal corporations of the State
of California, and the West Bay Sanitary District, a political subdivision of the State of California,
together with public agencies which, pursuant to contract with the Authority or its member agencies, use
the sanitary sewerage facilities of said member agencies and the Authority.
SECTION 1.3.3. AGENCY’S DIRECTOR or AGENCIES’ DIRECTORS.
The officer or employee of each Agency vested with the power by said Agency to administer its uniform
wastewater regulations, or his or her designees, including, but not limited to, duly authorized personnel
of Authority. The plural form shall refer to the Directors of all Agencies.
SECTION 1.3.4. AUTHORITY. The Joint Exercise of Powers Authority for the Silicon Valley
Clean Water, a public entity established by agreement between the Cities of San Carlos, Belmont, and
Redwood City, California, and the Menlo Park Sanitary District (now named the West Bay Sanitary
District) dated November 13, 1975, and any successor entity thereto.
SECTION 1.3.5. AUTHORITY’S COMMISSION. The governing body of Authority.
SECTION 1.3.6. AUTHORITY’S MANAGER. The Manager of the Authority, or his or her
designee.
SECTION 1.3.7. BUILDING SEWER. A sewer conveying wastewater from the premises of a
user to the sewerage facilities.
SECTION 1.3.8. BENEFICIAL USES. Uses of the waters of an Agency or the State which
may, or do require protection against quality degradation thereof, including, but not necessarily limited
to, waters used for domestic, municipal, agricultural, industrial, power generation, recreation, aesthetic
enjoyment, or navigation purposes, or for the preservation and enhancement of fish, wildlife or other
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page 3
aquatic resources or reserves, and such other uses, both tangible or intangible, as are or may be
specified by federal or state law as beneficial uses.
SECTION 1.3.9. CATEGORICAL STANDARDS. National pretreatment standards
specifying quantities or concentrations of pollutants or pollutant properties which may be discharged
into the sewerage facilities by existing or new industrial users classified in specific industrial
subcategories established as separate regulations under the appropriate subpart of 40 Code of Federal
Regulations, Chapter I, Subchapter N. Unless specifically provided otherwise, said standards shall be
adhered to in addition to the general prohibitions established in Article II of these regulations.
SECTION 1.3.10. CHARGE. A rental or other charge established pursuant to these regulations
or an Agency’s uniform wastewater ordinance for services and facilities furnished by the Authority or an
Agency to any premises in connection with
the operation of the sewerage facilities.
SECTION 1.3.11. COMPATIBLE POLLUTANT. Biochemical oxygen demand, suspended
solids, pH and fecal coliform bacteria, additional pollutants identified in the Authority’s NPDES permit,
and such other pollutants as may be designated by Authority’s Manager upon a finding by him or her
that such pollutants are substantially treated and removed by the sewerage facilities.
SECTION 1.3.12. CONTAMINATION. An impairment of the quality of the waters of an
Agency or the State by waste to a degree which creates a hazard to the public health. Contamination
shall include any equivalent effect resulting from the disposal of wastewater whether or not waters of an
Agency or State are affected thereby.
SECTION 1.3.13. DETRIMENTAL DISCHARGE. A discharge which, alone or in conjunction
with a discharge or discharges from other sources, does, or may, endanger the health, safety or welfare
of persons, or the environment, or threatens to, or reasonably may be deemed to threaten, the operation
of the sewerage facilities, or causes or may reasonably be deemed to cause a violation of the Authority’s
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NPDES permit, or any applicable federal, state, or local regulation relating to the operation of the
sewerage facilities.
SECTION 1.3.14. HAZARDOUS WASTE. Any liquid, semisolid, solid, or gaseous waste which
conforms to the definition of "Hazardous Waste" in Section 25117 of the California Health & Safety
Code, as said section may from time to time be amended, revised or recodified.
SECTION 1.3.15. HOLDING TANK WASTE. Any waste from sewage or waste disposal
holding tanks as, e.g., those which are associated with vessels, chemical toilets, campers, trailers, septic
tanks, and vacuum pump tank trucks.
SECTION 1.3.16. INCOMPATIBLE POLLUTANT. Any pollutant which is not a compatible
pollutant.
SECTION 1.3.17. INTERFERING DISCHARGE. A discharge into the sewerage facilities
which, alone or in conjunction with a discharge or discharges from another source or sources, inhibits or
disrupts the sewerage facilities, the treatment processes or operations thereof, the sludge processes
thereof, or the use or disposal of said sludge, or the disposal of sewage, and which causes or
significantly contributes to either a violation of the Authority’s NPDES permit or to the inability of the
Authority to use or dispose of sewage sludge in compliance with the federal or state regulations or
permits promulgated or issued thereunder.
SECTION 1.3.18. MASS EMISSION RATE. The weight of material discharged into the
sewerage facilities during a specified time interval. Unless otherwise specified, the mass emission rate
shall mean pounds per day of a particular waste constituent or combination of constituents.
SECTION 1.3.19. NEW SOURCE. Any building, structure, facility, or installation from which
there is or may be a discharge of Pollutants, the construction of which commenced after the publication
of proposed Pretreatment Standards under Section 307(c) of the Act which will be applicable to such
source if such Standards are thereafter promulgated in accordance with that section.
SECTION 1.3.20. NPDES PERMIT, OR AUTHORITY’S NPDES PERMIT.
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The National Pollutant Discharge Elimination System Permit issued to Authority pursuant to the
provisions of the Act, as said permit may from time to time be amended, revised or superseded.
SECTION 1.3.21. PASS THROUGH. The discharge of pollutants through the sewerage
facilities into surface waters in quantities or concentrations which cause or significantly contribute to
violation of the Authority’s NPDES permit.
SECTION 1.3.22. PERSON. Any individual, firm, company, partnership, association, private
corporation, public corporation, or governmental entity, authority, or agency, and the officers, agents, or
employees of such organizations.
SECTION 1.3.23. POLLUTANT. The human-made or human-induced waste which alters the
chemical, physical, biological, or radiological integrity of waters of an Agency or of the State
manifesting pollution.
SECTION 1.3.24. POLLUTION. An alteration of the chemical, physical, biological, or
radiological integrity of waters of an Agency or of the State by waste made or induced by humans which
unreasonably affects such waters for any beneficial use or so affects facilities serving such beneficial
use. The term pollution may also include contamination.
SECTION 1.3.25. PREMISES. A parcel of land, or portion thereof, including any
improvements thereon, which is directly or indirectly connected to the sewerage facilities for purposes
of receiving, using, and paying for service, or other purposes relating to the sewerage facilities, by an
individual user. Each dwelling unit of a duplex, apartment, or any other multi-family residence shall be
deemed separate premises. Subject to the foregoing, the Agencies’ Directors shall determine what
constitutes a premises.
SECTION 1.3.26. PRETREATMENT. The reduction of the amount of pollutants, the
elimination of pollutants, or the alteration of the nature of pollutant properties in wastewater to a less
harmful state prior to, or in lieu of, discharging or otherwise introducing such pollutants into the
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sewerage facilities. Such reduction or alteration may be obtained by physical, chemical or biological
processes, or process changes or other means, except as prohibited by requirements of law.
SECTION 1.3.27. RECLAIMED WATER. Water which, as a result of treatment of waste, is
suitable for direct beneficial use, or a restricted beneficial use, which would not otherwise occur but for
such treatment.
SECTION 1.3.28. REQUIREMENT OF LAW or OTHER REQUIREMENTS OF LAW. Any
pertinent provision of the Act, or of any statute, ordinance, rule, regulation, order, or directive
implementative of the Act, or of Authority’s NPDES permit, or of any amendments, revisions, or other
superseding provisions or requirements of the foregoing authorities.
SECTION 1.3.29. SEWERAGE FACILITIES. Any or all devices, facilities, equipment,
improvements or systems owned or used by the Agencies or the Authority in the collection, storage,
treatment, recycling, reclamation, or disposal of wastes or wastewater, including interceptor sewers,
outfall sewers, or lines, sewage collection systems, pumps, power plants, treatment plants, recycling or
reclamation plants, and other equipment and appurtenances thereto; extensions, improvements,
remodeling, modifications, additions or alterations thereof; chemicals, materials, or supplies used in
connection therewith; or any other facilities, including land and improvements thereon, which are an
integral part of the sewage collection, transporting or treatment process of the Agencies or the Authority,
or which are used for ultimate disposal of residues, effluent, or discharges resulting from such treatment,
or any other method or system for preventing, abating, reducing, storing, treating, separating or
disposing of wastes or wastewater, including storm water runoff, industrial wastes, domestic wastes, or
any combination thereof.
SECTION 1.3.30. SIGNIFICANT INDUSTRIAL USER.
(a) Any user within an industry subject to Categorical Pretreatment Standards under 40 CFR
chapter I, subchapter N; or
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(b) Any user that discharges an average of 25,000 gallons per day or more of process wastewater
to the POTW (excluding sanitary, non-contact cooling and boiler blowdown wastewater); or
(c) Any user that contributes a process wastestream which makes up 5 percent or more of the
average dry weather hydraulic or organic capacity of the POTW treatment plant; or
(d) Any user within a user classification listed in Division D (Manufacturing) of the Standard
Industrial Classification Manual, 1972 edition, issued by the Executive Office of the President, Office
of Management and Budget, as said manual may from time to time be amended, revised, or superseded,
who or which discharges 1,000 gallons or more per day of process wastewater into the sewerage
facilities; or
(e) Any user who or which discharges, or causes or permits a discharge of wastewater which
would or does have a reasonable potential for adversely affecting the sewerage facilities or for violating
any pretreatment standard or requirement (as determined by an Agency’s Director or Authority’s
Manager), either individually or in combination with other contributing industries, on the sewerage
facilities, or on the quality, of effluent from the sewerage facilities.
(f) Upon a finding that a user, meeting the criteria above in subsections (b) through (d), has no
reasonable potential for adversely affecting the sewerage facilities or for violating any pretreatment
standard or requirement, the Authority may at any time, on its own initiative or in response to a petition
received from a user or agency, and in accordance with 40 CFR 403.8(f)(6), determine that such user is
not a significant industrial user.
SECTION 1.3.31. UNPOLLUTED WATER. Water to which no constituent has been added,
either intentionally or accidentally, which would render such water unacceptable to an Agency or the
Authority for disposal to storm or natural drainages, or directly to surface waters.
SECTION 1.3.32. USER. Any person who or which discharges, causes or permits the discharge
of wastewater into the sewerage facilities.
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SECTION 1.3.33. USER CLASSIFICATION. A classification of users based upon
classifications set forth in the Standard Industrial Classification Manual, 1972 edition, issued by the
Executive Office of the President, Office of Management and Budget, as said manual may from time to
time be amended, revised, or superseded.
SECTION 1.3.34. WASTE. Sewage and any and all waste substances, whether liquid, solid,
gaseous, or radioactive, associated with human habitation, or of human or animal origin, or from any
producing, manufacturing or processing operation of whatever nature, including such waste placed
within containers of any nature prior to, and for purposes of, disposal.
SECTION 1.3.35. WASTEWATER. Waste and water, whether treated or untreated, discharged
into, or permitted to enter into the sewerage facilities.
SECTION 1.3.36. WASTEWATER CONSTITUENTS AND CHARACTERISTICS.
The individual chemical, physical, bacteriological and radiological parameters, including volume
and flow rate, and such other parameters that serve to define, classify or measure the contents, quality,
quantity, or strength of wastewater.
SECTION 1.3.37. WATERS OF THE AGENCIES OR STATE. Any water, whether surface,
underground, and whether saline or non-saline, within the boundaries of the agencies, or within the
boundaries of an Agency flowing into, touching, or otherwise combined with waters outside the limits of
said Agency but within the boundaries of the State.
ARTICLE II. PROHIBITIONS.
SECTION 2.1 GENERAL PROHIBITIONS.
(a) No person shall discharge waste into the sewerage facilities which cause, threaten to cause, or
are capable of causing, either alone or by interaction with other substances:
(1) A fire or explosion;
(2) Obstruction of flow in, or injury to, the sewerage facilities, or any portion thereof;
(3) Danger to life or safety of persons;
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(4) Conditions inhibiting or preventing the effective maintenance or operation of the
sewerage facilities;
(5) Strong or offensive odors, air pollution, or any noxious, toxic, or malodorous gas or
substance, or gas producing substances;
(6) Interference with the wastewater treatment process, or overloading of the sewerage
facilities, or excessive collection or treatment costs, or use of a disproportionate share of
the capacity of the sewerage facilities;
(7) Interference with any wastewater reclamation process, which does or may operate in
conjunction with the sewerage facilities, or overloading, or a breakdown of such
reclamation process, or excessive reclamation costs, or any product of the treatment
process which renders such reclamation process impracticable or not feasible under
normal operating conditions;
(8) A detrimental environmental impact, or a nuisance wherever located, or a condition
unacceptable to any public agency having regulatory jurisdiction over operation of the
sewerage facilities;
(9) Discoloration, or any other adverse condition in the quality of the effluent from the
sewerage facilities such that receiving water quality requirements established by any
statute, rule, regulation, ordinance, or permit condition cannot be met by an Agency or
the Authority;
(10) Conditions at or near the sewerage facilities, or any portion thereof, which cause, or may
cause, an Agency or Authority to be in violation of the requirements of law.
(11) Pollutants introduced into the sewerage facilities which pass through or interfere with the
operation or performance of the sewerage facilities.
(b) No person shall discharge hazardous waste into the sewerage facilities except pursuant to
a permit issued by Authority’s Manager upon a determination that such hazardous waste will not
constitute or create a detrimental discharge.
(c) Except pursuant to an express applicable Pretreatment Standard, no user shall ever
increase the use of process water or, in any other way, attempt to dilute a discharge of waste or
wastewater as a partial or complete substitute for adequate treatment to achieve compliance with a
Pretreatment Standard. The Authority may impose limitations upon mass emission rates on users which
are using dilution to meet applicable Pretreatment Standards or in other cases where the imposition of
mass limitations is appropriate.
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SECTION 2.2. SPECIFIC SOURCES PROHIBITED. No person shall discharge, cause to be
discharged, or permit to be discharged, either directly or indirectly into the sewerage facilities, waste or
wastewater from any of the following sources unless a permit therefor is issued by an Agencyts Director
subject to the concurrence of Authority’s Manager:
(a) Any stormwater, groundwater, rainwater, street drainage, sub-surface drainage, or yard
drainage;
(b) Any unpolluted water, including, but not limited to, cooling water, process water, or
blow-down water from cooling towers or evaporative coolers;
(c) Waste from garbage grinders, provided, that wastes generated in preparation of food
normally consumed on the premises may be so discharged, provided, further, that such
grinders shall be of such design and capacity to shred waste used therein such that all
waste particles shall be carried freely under normal flow conditions into and through the
sewerage facilities;
(d) Any wastes or wastewater, or any object, material, or other substance directly into a
manhole or other opening into the sewerage facilities other than wastes or wastewater
through an approved building sewer;
(e) Any holding tank waste, provided, that such waste may be placed into facilities designed
to receive such wastes and approved by an Agency’s Director;
(f) Any radioactive waste, provided, that persons authorized to use radioactive materials by
the State Department of Health or other governmental agency with regulatory jurisdiction
over the use of radioactive materials may discharge, cause to be discharged, or permit to
be discharged such wastes, provided that such wastes are discharged in strict
conformance with current California Radiation Control regulations (California Code of
Regs. Title XVII, Ch. 5, Sub.Ch. 4, Group 3, Art. 5), and federal regulations and
recommendations for safe disposal of such wastes, and, provided further, that the person
so acting does so in compliance with all applicable rules and regulations of all other
regulatory agencies having jurisdiction over the matter.
SECTION 2.3. WASTEWATER STRENGTH LIMITATIONS. Except pursuant to a permit
issued under Section 2.5, no Person shall discharge, cause to be discharged, or permit to be discharged
any Wastewater into the Sewerage Facilities containing any of the following Wastewater constituents in
excess of the maximum allowable amounts respectively hereinafter established therefor:
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Amount in Milligrams
Wastewater Constituent per Liter (mg/L) (a) Arsenic 0.1
(b) Cadmium 0.04
(c) Chromium 0.2
(d) Copper 0.2
(e) Lead 0.2
(f) Mercury 0.002
(g) Nickel 0.06
(h) Silver 0.1
(i) Zinc 1.0
(j) Pheno1ic Compounds 2.6
(k) Cyanide 0.06
(1) Polycyclic Aromatic Hydrocarbons 0.2
(m) Methylene Chloride 0.07
(n) Chloroform 0.03
(o) Perchloroethylene 0.03
(p) Benzene 0.002
(q) Carbon Tetrachloride 0.001
(r) Carbon Disulfide 0.008
SECTION 2.4. SPECIFIC WASTES PROHIBITED. No Person shall discharge, cause to be
discharged, or permit to be discharged any Wastewater into the Sewerage Facilities:
(a) The temperature of which is higher that 150° Fahrenheit (65° centigrade); (b) Containing more than 300 mg/l of oil or grease of animal or vegetable origin; (c) Containing more than 100 mg/l of oil or grease of mineral or petroleum origin; (d) Having a pH lower than 6.0 or having a corrosive property capable of causing damage or
hazard to structures or equipment of the Sewerage Facilities, or any portion thereof; (e) Any sand, grit, straw, metal, glass, rags, feathers, paper, tar, plastic, wood, leaves, garden
clippings, manure, dead animals, offal, or any other solid or viscous substance capable of causing obstruction to the flow in the Sewerage Facilities, or which in any way interferes with the proper operation of the Sewerage Facilities;
(f) Any Pollutant not otherwise specifically prohibited in these regulations, in sufficient
quantities to constitute a hazard to humans or animals, or to create a hazard to the Sewerage Facilities, or to injure or interfere with the operation thereof;
(g) Any Waste containing suspended solids not otherwise specifically prohibited under the
provisions of these regulations, the characteristics or quantity of which require or requires unusual attention, treatment, or expense in handling or treating in the Sewerage Facilities, or any portion thereof;
(h) Any Waste streams with a closed cup flashpoint of less than l40 Fahrenheit
(i) Any trucked or hauled Wastes except at points designated by the Authority or Agency.
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SECTION 2.5. SPECIFIC USER LIMITATIONS. Notwithstanding the limitations upon the
characteristics or quantity of Wastewater discharged, caused to be discharged, or permitted to be
discharged into the Sewerage Facilities pursuant to this Article, Authority’s Manager may, in connection
with the issuance of permits pursuant to the provisions of Article IV, establish additional or different
specific limitations on Wastewater strength, or deny an application for any such permit, upon a finding
by him or her that:
(a) The limitations set forth in this Article may not be sufficient to protect the operation of
the Sewerage Facilities, or any portion thereof, or the Waste or Wastewater proposed to
be discharged constitutes a hazard to, or an unreasonable burden upon, such operation, or
otherwise causes or may cause, or significantly contributes, or may contribute, to a
violation of Authority’s NPDES Permit; or
(b) The limitations set forth in Section 2.3 may be unreasonably restrictive when applied to a
specific User or User Category and the proposed discharge, if allowed, when added to the
total amount authorized by existing permits issued pursuant to these regulations will not
cause the amount of any of the following Wastewater constituents to exceed the
aggregate maximum allowable amount respectively hereinafter established therefore:
Aggregate Maximum Permitted Amounts Wastewater Constituent in Pounds per day (lbs/day) (i) Arsenic 11.4 (ii) Cadmium 6.11 (iii) Chromium 31.3 (iv) Copper 19.9 (v) Lead 22.7 (vi) Mercury 0.915 (vii) Nickel 6.82 (viii) Silver 12.5 (ix) Zinc 113.0 (x) Phenolic Compounds 385.0 (xi) Cyanide 5.25 (xii) Polycyclic Aromatic Hydrocarbons 15.2
(c) Notwithstanding the provisions of (a) and (b) above, in no event shall any permit be
issued which allows an Interfering Discharge, or a Pass Through, or allows a violation of
a Categorical Standard.
ARTICLE III. WASTEWATER VOLUME DETERMINATION.
SECTION 3.1. GENERAL. For the purposes of these regulations unless otherwise provided
pursuant to the provisions of this Article, wastewater volumes shall be determined upon the basis of
volumes of freshwater, including all sources of non-wastewater, used by, or furnished to, a user.
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SECTION 3.2. METERING. Upon application of a user, and upon a finding by Authority’s
Manager, subject to the concurrence of the Agency’s Director of the Agency within the boundaries of
which the premises to be served by the sewerage facilities is located, that a significant portion of
freshwater or non-wastewater, received by the user from any metered source does not flow into the
sewerage facilities because of the principal activity of the user, or by reason of removal of wastewater
by other means, Authority’s Manager, with the concurrence of said Agency’s Director, may authorize
determination of the volume of wastewater discharge to be made by an appropriate metering device.
Upon such determination, a metering device, of a type approved by Authority’s Manager, and at a
location approved by Authority’s Manager, shall be installed at the user’s expense. Such metering
device shall measure either the amount of wastewater discharged into the sewerage facilities, or the
amount of freshwater or non-wastewater diverted from the sewerage facilities. Upon installation, such
meters shall be maintained and tested periodically for accuracy in accordance with requirements
established by Authority’s Manager, all of which maintenance and testing shall be at the expense of the
user.
SECTION 3.3. EXCEPTIONS - ESTIMATED VOLUME. In lieu of use of a metering device
as specified in section 3.2, and upon a determination by Authority’s Manager, subject to the concurrence
of the Agency’s Director of the Agency within the boundaries of which the premises to be served by the
sewerage facilities is located, that it would be unnecessary or impracticable to install, maintain, or
operate such metering device, wastewater volume discharged by a user into the sewerage facilities may
be based upon an estimate thereof determined by Authority’s Manager, with the concurrence of said
Agency’s Director. The determination of such estimated wastewater volume shall be based upon such
factors as the number of fixtures through which wastewater flows into the sewerage facilities from the
user’s premises, seating capacity of buildings or improvements upon the premises, the population
equivalent associated with the premises, annual production of goods and services related to the premises,
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or other factors reasonably relating to water use, wastewater volume calculations, and/or diversions of
wastewater flow from the sewerage facilities.
SECTION 3.4. BASIS FOR DETERMINATION, AGENCY’S CONCURRENCE. The
determination by Authority’s Manager to require measurement of wastewater volumes by metering
devices or calculation of estimated flows pursuant to Section 3.2 or 3.3, respectively, shall be based
upon such data, statistics, description of premises to be served by the sewerage facilities and operations
conducted thereon together with corresponding reasons submitted by the user in support of use of such
metering devices or calculations, as the case may be, and such other information deemed necessary or
appropriate by Authority’s Manager to enable him or her to make a reasoned determination.
ARTICLE IV. REPORTS, PERMITS AND ADMINISTRATION.
SECTION 4.1. REPORTS.
SECTION 4.1.1. GENERAL. Reports required to be submitted pursuant to permits issued under
these regulations or otherwise required by the Act, or regulations implementative thereof, including, but
not limited to, compliance schedule progress reports, reports on compliance with categorical deadlines,
periodic compliance reports, notice of changed discharge reports, and reports from noncategorical
industrial users, shall conform to pertinent provisions of such permits, these regulations, or other
requirements of law, and shall be submitted in accordance with applicable filing requirements,
including, but not limited to, deadlines.
SECTION 4.1.2. PERIODIC DISCHARGE REPORTS. In addition to all other reports which
may be required to be submitted by a user, upon a determination by Authority’s Manager, or the
Agency’s Director of the Agency within the boundaries of which the premises to be served by the
sewerage facilities is located, that such information is necessary or appropriate for them reasonably to
carry out their respective duties and to exercise their respective authority under these regulations, each
or either of them may require that any person discharging, causing to be discharged, permitting to be
discharged, or proposing to discharge wastewater into the sewerage facilities shall file a periodic
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discharge report, the cost of which shall be borne by such person. Such report may include, but shall not
necessarily be limited to, information relating to the nature of manufacturing, fabricating, or other
processes, fresh or non-wastewater volumes, wastewater volumes, rates of flow, mass emission rates,
production quantities, hours of operation, number and classification of employees, or other information
relating to the generation of waste, including wastewater constituents and characteristics of the pertinent
wastewater discharge. Authority’s Manager or said Agency’s Director may also require that such reports
include chemical constituents and quantity of liquid or gaseous materials stored on the premises relating
to such discharge, even though such materials are not normally discharged into, or become a part of the
wastewater in, the sewerage facilities.
Such reports shall be in addition to self-monitoring reports, information furnished in connection
with wastewater discharge permits, or other permits authorized under these regulations. The reports
authorized and required under this section shall be filed with Authority’s Manager or said Agency’s
Director periodically and/or at such other times as either of them may reasonably require.
SECTION 4.1.3. SIGNATORY REQUIREMENTS. Baseline and Monitoring Reports, 90 Day
Compliance Reports, and Periodic Reports on Continued Compliance (as said reports are defined and
described in Subdivisions (b), (d) and (e) of Section 403.12 of Title 40, Code of Federal Regulations,
and such other reports as may be specified by Authority’s Manager, shall be signed by an authorized
representative of the industrial user, or other user or other person required to submit such report. An
authorized representative may be:
(1) A principal executive officer of at least the level of vice president, if the industrial user,
other user or other person submitting such report is a corporation;
(2) A general partner or proprietor if the industrial user, other user, or other person
submitting such report is a partnership or sole proprietorship, respectively; or
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(3) A duly authorized representative of the individual designated in (1) or (2) above, if such
representative is responsible for the overall operation of the facility with respect to which such report
pertains.
SECTION 4.1.4. CERTIFICATION. Reports required to be submitted pursuant to permits
issued under these regulations, or otherwise required that by these regulations, by the Act, or by
regulations implementative thereof, shall, unless otherwise specified by Authority’s Manager, include
the following certification of the signatory thereto:
"I certify under penalty of law that this document and all attachments were prepared
under my direction or supervision in accordance with a system designed to assure that qualified
personnel properly gathered and evaluated the information submitted. Based on my inquiry of
the person or persons directly responsible for gathering the information, or the person or persons
who has or have knowledge of the substance of the information, the information submitted is, to
the best of my knowledge and belief, true, accurate and complete. I am aware that there are
significant penalties for submitting false information, including the possibility of a fine and
imprisonment for knowing violations."
SECTION 4.2. MANDATORY WASTEWATER DISCHARGE PERMITS. No significant
industrial user shall connect to, or discharge waste or wastewater into, the sewerage facilities without
first obtaining a wastewater discharge permit therefor. No significant industrial user, or other user
discharging, or proposing to discharge wastewater having characteristics or quantities equivalent to that
of a significant industrial user whose premises are connected to the sewerage facilities upon the effective
date of these regulations shall discharge wastewater into the sewerage facilities on or after 90 days after
such effective date without a wastewater discharge permit therefor.
SECTION 4.3. DISCRETIONARY WASTEWATER DISCHARGE PERMITS. A wastewater
discharge permit may be issued to any user, upon application therefor, who (1) requests that charges and
fees established pursuant to these regulations be based upon an estimated volume of wastewater
discharged, or to be discharged, into the sewerage system, or (2) establishes to the satisfaction of
Authority’s Manager that wastewater proposed to be discharged from such user’s premises into the
sewerage system has, or will have, wastewater strength characteristics less than the normal range for the
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user classification to which such user is assigned, by reason of pretreatment, process changes, or other
factors affecting such wastewater characteristics, or (3) requests or requires a permit pursuant to the
provisions of Sections 2.1(b), 2.2., or 2.5.
SECTION 4.4. WASTEWATER DISCHARGE PERMITS.
SECTION 4.4.1. APPLICATIONS FOR MANDATORY WASTEWATER DISCHARGE
PERMITS. Applications for mandatory permits required under Section 4.2 shall be made to Authority’s
Manager in writing in such form as Authority’s Manager shall require, and shall set forth the following:
(a) The name and address of the applicant/user and the business name or other designation by which the premises or facility located thereon to which the application pertains is known, the address of said premises or facility (if different than the name and address of the applicant), and the name or names of the manager or other person in charge of said facility or premises;
(b) A list of any environmental control permits held by the applicant for the facility or
premises;
(c) A brief description of the nature, average rate of production and standard industrial classification of the operation(s) carried out by the applicant;
(d) Flow measurement showing average daily and maximum daily flow from each process
stream to which the application pertains;
(e) Wastewater constituents and characteristics of the wastewater proposed to be discharged into the sewerage facilities, including, but not limited to, those categories thereof described in Sections 2.2, 2.3, and 2.4, the presence and amount of which shall be determined by a laboratory competent to test and describe such constituents and characteristics, and approved by Authority’s Manager;
(f) The time and duration of the proposed wastewater discharge; (g) The average and thirty minute peak wastewater flow rates proposed to be discharged,
including daily, monthly, and seasonal variations, if any; (h) Site plans, floor plans, mechanical and plumbing plans, in detail necessary or appropriate
to show and to describe all building sewers and appurtenances by size, location and elevation;
(i) A description of the activities, facilities, and plant processes conducted, or proposed to be
conducted on the premises, including, but not necessarily limited to, all materials manufactured, fabricated, or processed, and the types of materials which are or could be discharged into the sewerage facilities;
(j) Identification of pretreatment standards applicable to each process;
(k) A statement, reviewed by an authorized representative of the applicant and certified by a
qualified professional, stating whether categorical standards are being or will be met on a consistent basis and, if not, whether additional operation and maintenance and/or
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additional pretreatment is required for the applicant to meet such standards and requirements;
(1) Requirements, if any, for additional pretreatment and/or operation and maintenance in
order to meet categorical standards and the shortest schedule by which the applicant will provide such additional pretreatment and/or operation and maintenance (the completion date in said schedule shall not be later than the compliance date established for any applicable categorical standard);
(m) Such other information deemed necessary by Authority’s Manager to determine the effect
upon the sewerage facilities of the proposed discharge or activities related thereto, or otherwise reasonably necessary to enable Authority’s Manager or the Agency’s Director of the Agency within the boundaries of which the premises to be served by the sewerage facilities is located, to carry out the provisions of these regulations, or any other requirements of law.
SECTION 4.4.2. APPLICATIONS FOR DISCRETIONARY WASTEWATER DISCHARGE
PERMITS. Applications for wastewater discharge permits which may be issued pursuant to Section
2.1(b), Section 2.2, Section 2.5 and Section 4.3, shall be made to Authority’s Manager in writing in such
form as Authority’s Manager shall require and shall set forth the following:
(a) The name and address of the applicant/user and the business name (if applicable) or other designation by which the premises or facility located thereon to which the application pertains is known, the address of said premises or facility (if different then the name and address of the applicant), and the name or names of the manager or other person in charge of said facility or premises;
(b) The time and duration of the proposed wastewater discharge; (c) A description of the activities, facilities, or other operations pertaining to the proposed
discharge including, but not necessarily limited to, types of materials which are or could be discharged into the sewerage facilities;
(d) Such other information deemed necessary by Authority’s Manager to determine the effect
upon the sewerage facilities of the proposed discharge or activities related thereto, or otherwise reasonably necessary to enable Authority’s Manager or the Agency’s Director of the Agency within the boundaries of which the premises from or with respect to which the proposed discharge is located, to carry out the provisions of these regulations, or any other requirements of law.
SECTION 4.4.3. SIGNATORY REQUIREMENTS. Applications for permits shall be signed by
the persons designated in Section 4.1.3 (pertaining to signatories for certain reports) and shall contain
the certification specified in Section 4.1.4 (pertaining to certification for certain reports).
SECTION 4.4.4. ISSUANCE. Upon evaluation of and approval of all pertinent data and
information, Authority’s Manager shall issue a wastewater discharge permit, subject to the consent of
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the Agency’s Director of the Agency within the boundaries of which the premises to be served by the
sewerage facilities is located, and further subject to terms and conditions required or authorized under
the provisions of these regulations, the said Agency’s regulations pertaining to use of its sewerage
facilities not inconsistent with these regulations, and deemed necessary or appropriate by Authority’s
Manager or said Agency’s Director, as the case may be, to carry out the purposes and intent of these
regulations or said Agency’s regulations.
SECTION 4.5. PERMIT CONDITIONS.
SECTION 4.5.1. GENERAL. Wastewater discharge permits authorized under these regulations
shall be subject to all applicable provisions and requirements of these regulations, the regulations of the
Agency within the boundaries of which the premises to be served by the sewerage facilities is located
and which are implementative hereof and not inconsistent with the provisions of these regulations, and
to all other applicable requirements of law.
SECTION 4.5.2. EXPRESS CONDITIONS. Permits authorized under these regulations may
include any or all of the following:
(a) The unit charge or schedule of charges and fees for the service and use of the sewerage
facilities to be paid by the permittee, and the terms and conditions of such payment;
(b) The allowable average and maximum wastewater constituents and characteristics thereof
permitted to be discharged into the sewerage facilities;
(c) Limitations upon time and rate of wastewater discharge, or requirements for flow
regulations and equalization thereof;
(d) Requirements for the installation of inspection, sampling or testing facilities;
(e) Pretreatment requirements;
(f) Specifications for monitoring programs which may include, but shall not necessarily be
limited to, sampling locations, frequency and method of sampling, number, types and
standards for tests, and reporting schedule;
(g) Requirements for submission of technical reports or wastewater discharge reports;
(h) Requirements for maintaining, for not less than 3 years, plant records relating to the
wastewater discharge as specified by Authority’s Manager and providing for access
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thereto of Authority’s Manager or the Agency’s Director of the Agency within the
boundaries of which the premises to be served by the sewerage facilities is located,
including provisions pursuant to which such records shall be made available for copying
and inspection by Authority’s Manager or said Agency’s Director;
(i) The mean and maximum mass emission rates, or other appropriate limits when
incompatible pollutants are proposed to be discharged into, or are present in, the
permittee’s wastewater discharge;
(j) Requirements for submission, prior to closure or abandonment of the permittee’s
facilities, of a closure plan detailing the means by which the permittee’s sanitary
facilities, including pretreatment facilities, shall be secured upon such closure or
abandonment; and
(k) Such other conditions, requirements, or provisions deemed appropriate by Authority’s
Manager or the aforesaid Agency’s Director to ensure compliance with the provisions of
these regulations, or said Agency’s regulations, or other requirements of law.
SECTION 4.6. DURATION OF PERMITS. Wastewater discharge permits authorized under
these regulations shall be effective for the period described therein, but in any event, for no longer than
five years from the date of issuance. The period specified in a permit may be less than a year, may be
expressed in years, or may specify a date of expiration.
Upon expiration of the express term of wastewater discharge permit, the term thereof shall be
deemed renewed automatically for successive 1-year periods, the first of which shall commence upon
the day next following the last day of the express term; provided, however, that in the event Authority’s
Manager gives written notice to the permittee of the termination or expiration of the permit not less than
30 days prior to the expiration of the express term thereof, or prior to the expiration of any successive 1-
year term thereof, then a new permit shall be required subject to the provisions of these regulations.
Every permit shall be subject to modification, amendment, or other revision during the term
thereof by Authority’s Manager with the concurrence of the Agency’s Director of the Agency within the
boundaries of which the premises to which the permit pertains is located, as determined necessary by
Authority’s Manager and said Agency’s Director in order to obtain compliance by the user with the
requirements of these regulations, or other requirements of law. To the extent practicable, Authority’s
Manager shall give written notice to a permittee of any proposed modification, amendment or revision
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not less than 30 days prior to the effective date of such modification, amendment or revision. To the
extent reasonably necessary or appropriate, Authority’s Manager may specify a reasonable time
schedule for compliance with any new conditions, provisions, or requirements established by
modification, amendment or revision to a permit.
SECTION 4.7. NON-ASSIGNABILITY. Wastewater discharge permits shall be personal to
each permittee, and shall relate only to the use or operation described therein. No person shall assign,
reassign, sell, lease, sublet, or otherwise transfer a wastewater discharge permit, or any interest therein,
to any person other than the permittee, or use, cause to be used, or permit to be used, such permit in
connection with a different premises, or a different operation than that specified in the permit, or with a
new, expanded, or modified operation.
SECTION 4.8. MONITORING FACILITIES. Authority’s Manager may require a user to
construct, operate, and maintain, at the user’s own expense, monitoring, sampling, or metering facilities
or other equipment to allow inspection, sampling, and flow measurement of the user’s building sewer, or
internal drainage systems, or waste or wastewater discharges. Such monitoring, sampling, or metering
facilities or equipment shall be located on the user’s premises; provided, however, that Authority’s
Manager may allow such equipment or facility to be constructed upon public property adjacent to the
user’s premises upon a determination by Authority’s Manager, with the concurrence of the Agency’s
Director of the Agency within the boundaries of which the premises to which the permit pertains is
located, that location of such equipment or facilities upon the user’s premises would be impracticable or
cause unnecessary or undue hardship. In the event that Authority’s Manager makes the foregoing
determination with the concurrence of said Agency’s Director, and the public property upon which such
facilities or equipment are proposed to be constructed or installed is outside said Agency’s boundaries,
the user shall obtain permission for such installation or construction, and for the maintenance and
operation of such facilities or equipment, from the governmental Agency which owns or exercises
managerial control over such property.
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Monitoring, sampling, or metering facilities or equipment to be provided, installed, maintained
and operated pursuant to the provisions of this section shall be so situated, constructed and installed as to
permit safe and immediate access thereto by Authority’s Manager; provided, however, that Authority’s
Manager may, at the option of the user, secure such equipment or facilities with a lock furnished by
Authority’s Manager, at the expense of the user. The user shall provide sufficient space, as determined
by Authority’s Manager, at or near such equipment or facilities so as to allow ready and accurate
monitoring, sampling, and compositing of samples for analysis. Such equipment and facilities, and the
sampling and measuring equipment to be maintained and operated in connection therewith, shall be so
maintained and operated at all times in a safe and proper condition, by and at the expense of the user.
Monitoring, sampling or metering equipment or facilities to be furnished pursuant to the
provisions of this section shall be provided in accordance with all reasonable requirements of
Authority’s Manager relating thereto, and all applicable construction standards and specifications of the
Agency, or other governmental authority regulating such matters wherein such equipment or facilities
are located. Installation and construction of such facilities or equipment shall be completed within 90
days following written notification requiring such installation or construction from Authority’s
Manager; provided, however, that Authority’s Manager may, at his or her discretion, extend the time of
performance of such installation or construction.
SECTION 4.9. INSPECTION AND SAMPLING. Authority’s Manager is hereby authorized to
inspect the premises, and inspect and copy the records, of any user at all reasonable times to ascertain
whether such user is in compliance with the provisions of these regulations, or the provisions of any
permit issued pursuant to these regulations. Owners or occupants of premises where wastewater is
created, held or discharged shall allow Authority’s Manager ready access at all such reasonable times to
all parts of the premises for the purposes of inspecting the facilities and appurtenances thereon,
inspecting and copying records, sampling, monitoring, or performing any or all of the duties reasonably
necessary or appropriate in carrying out or enforcing the provisions of these regulations, or any permit
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issued pursuant to these regulations. Authority’s Manager shall further have the right to install and use
on the user’s premises such devices as are reasonably necessary or appropriate to conduct sampling,
metering, or monitoring operations or other of the aforesaid duties. In the event a user has established
security measures requiring identification and clearance prior to entry onto such user’s premises, the
user shall furnish and provide such identification or clearance to Authority’s Manager so as to permit
ready access of Authority’s Manager to the premises for the purposes described in this section.
SECTION 4.10. PRETREATMENT. Pretreatment of wastes or wastewater shall be furnished
by every user on the user’s premises when such waste or wastewater, prior to pretreatment, does not
comply with the minimum acceptable requirements and criteria therefor for discharge into the sewerage
facilities as set forth in Article II. Such pretreatment facilities shall be provided and maintained at the
user’s expense, and shall be of sufficient design and capacity to pretreat waste or wastewater discharged
from the premises into the sewerage facilities to a level meeting such minimum requirements, and such
other requirements established by Authority’s Manager reasonably necessary or appropriate for the
sewerage facilities to treat adequately such waste or wastewater under normal operating and treatment
conditions.
Prior to the installation of pretreatment facilities, plans and specifications therefor shall be
submitted to Authority’s Manager, together with such data and descriptive material relating to the waste
or wastewater prior to, and after such proposed pretreatment as Authority’s Manager may require, in
order that Authority’s Manager may ascertain the wastewater constituents and characteristics and
volume of the wastewater discharge after pretreatment. The user shall make such modifications,
amendments or revisions to said plans and specifications as Authority’s Manager may reasonably
require in order that the provisions of these regulations, or any permit issued, or to be issued pursuant to
these regulations, shall be complied with. Upon approval of such plans and specifications by Authority’s
Manager, the user may proceed with the construction of the pretreatment facilities in conformance
therewith; provided, however, that such approval shall not be deemed to waive or modify any other
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requirement of these regulations, or of any permit issued pursuant to these regulations, or of any other
requirements of law.
Approval of plans and specifications of pretreatment facilities pursuant to this section shall not
relieve the user from the responsibility of modifying such pretreatment facilities as necessary to produce
effluent therefrom complying with all pertinent provisions of these regulations, or any permit issued
pursuant to these regulations, or any other requirements of law. Any proposed cessation of use, or
alteration, modification, or other change to approved pretreatment facilities or any portion thereof, or
any change in method of operation thereof, shall be reported to Authority’s Manager prior to
commencement thereof, and shall be subject to the approval of Authority’s Manager. Such approval may
be withheld, granted, or granted subject to such terms, conditions, or requirements as Authority’s
Manager may reasonably require in order to ensure compliance with the provisions of these regulations,
or any permit issued pursuant to the provisions of these regulations.
SECTION 4.11. ACCIDENTAL DISCHARGES. Every user shall provide protective measures
against accidental or unauthorized discharges of prohibited wastes, wastewater constituents or
characteristics, or volumes into the sewerage facilities as set forth in Article II, or as may be otherwise
set forth in any permit issued pursuant to these regulations. Such measures shall consist of operational or
other procedures and/or facilities as determined reasonably necessary or appropriate by Authority’s
Manager. All costs of such measures shall be borne by the user.
Authority’s Manager may specify standard procedures and/or facilities for each classification of
user, and, to the extent so specified, he or she is hereby authorized and directed to require the institution
and use of such procedures, and the installation and construction of such facilities for each such
classification. Alternatively, Authority’s Manager may require any user to propose such procedures
and/or facilities, which proposals shall be submitted to Authority’s Manager for review, with such
supporting plans, specifications, data, explanations, or other matters as may reasonably be required by
Authority’s Manager in order to ascertain the effectiveness of the procedures and/or facilities proposed.
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Authority’s Manager may require such revisions, amendments, modifications, or other changes to such
proposals, or approve, or reject the same, as Authority’s Manager deems reasonably necessary or
appropriate in order that such proposals ensure protection against accidental or unauthorized discharge.
SECTION 4.12. PUBLIC INFORMATION. All information and data furnished by, or
regarding the operations of, a user obtained from reports, questionnaires, permit applications, permits,
monitoring programs, inspections, or from other sources provided or required under the provisions of
these regulations shall be available to the public or other governmental agencies without restriction
unless the user requests in writing that such information be maintained confidential, and establishes to
the satisfaction of Authority’s Manager that the disclosure of the information to other persons would
result in unfair competitive disadvantage to the user; provided, however, that in no event shall
wastewater constituents, characteristics, or volumes be deemed confidential information.
Notwithstanding the foregoing, information approved by Authority’s Manager as confidential shall be
available for use by an Agency, the Authority, the State, the federal government, or any official or
agency of said entities, in connection with enforcement proceedings, or any judicial proceedings to
which the user is a party.
SECTION 4.13. SPECIAL AGREEMENTS. The provisions of these regulations shall not be
deemed a limitation upon the Authority or an Agency to enter into agreements, and to recover costs
relating thereto, with any user relating to treatment, pretreatment, or other matters in furtherance of the
provisions of these regulations and the purposes thereof, and not inconsistent therewith, when unique,
unusual or extraordinary circumstances require such special agreements; provided, however, that no
such agreement shall authorize an extension of the final dates for compliance with required federal
standards nor waive such standards.
ARTICLE V. CHARGES AND FEES.
SECTION 5.1. USER CLASSIFICATIONS, ADMINISTRATION. For the purpose of
imposing the charges and fees in this Article V authorized, Authority’s Commission shall, by resolution,
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establish user classifications based upon standard limitations upon wastewater characteristics,
constituents, and volumes uniformly applicable to users within each such classification, and shall
establish terms and conditions for payment and collection of such charges and fees.
SECTION 5.2. GENERAL. Authority’s Commission shall, by resolution, establish a schedule
of charges and fees to be imposed by Authority and collected from all owners of premises served by the
sewerage facilities, or from users of the sewerage facilities, based upon user classifications, for the use
of the sewerage facilities and services furnished to said premises or users, in such amounts as will
provide for each user to pay his or her proportionate share of the costs of operation and maintenance
(including replacement) of the sewerage facilities; provided, that such charges shall also provide for
payment by industrial users of the sewerage facilities of that portion, if any, of Authority’s treatment
works which is allocable to the treatment of such industrial user’s waste. The schedule of fees and
charges authorized hereunder shall also compensate Authority for services ancillary to the foregoing.
SECTION 5.3. SPECIFIC CHARGES AND FEES. Authority’s Commission may adopt
charges and fees which may include, but shall not necessarily be limited to:
(a) Fees for reimbursement of costs of establishing and operating Authority’s pretreatment program;
(b) Fees for monitoring, inspections and surveillance procedures; (c) Fees for reviewing accidental discharge procedures and construction; (d) Fees for processing permit applications and issuing permits; (e) Fees for processing and hearing appeals; (f) Fees for consistent removal by Authority of pollutants otherwise subject to Authority’s
pretreatment requirements;
(g) Such other fees and charges as Authority may deem necessary or appropriate to carry out the provisions of these regulations or otherwise to reimburse Authority for the transmission, treatment and disposal services provided by Authority.
SECTION 5.4. COMBINED FEES AND CHARGES. To the extent convenient or appropriate,
certain of the fees and charges authorized under this Article V may, with the consent of the governing
bodies of each of the Agencies, be combined with fees and charges imposed and collected by the
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Agencies, respectively. Nothing herein contained shall be deemed a limitation upon the obligation of the
Agencies to impose and collect uniform charges pursuant to the Joint Exercise of Powers Agreement
establishing Authority and described in Section 1.3.4.
SECTION 5.5. AGENCIES’ CHARGES EXCLUDED. Nothing contained in this Article V
shall be deemed a limitation upon each of the Agencies to impose and collect such fees and charges as
they, respectively, may establish with respect to that portion of the sewerage facilities furnished by said
Agencies, or with respect to ancillary services or facilities likewise so furnished.
ARTICLE VI. ENFORCEMENT.
SECTION 6.1. RESPONSIBILITY. The primary responsibility for enforcement of the
provisions of these regulations shall be vested in Authority’s Manager; provided, however, that said
Manager shall be, and he or she hereby is, authorized and empowered to delegate his or her authority
hereunder to such officers, employees or agents of Authority as he or she shall designate; and, provided
further, that field inspectors or other employees of Authority, upon written certification thereof from
Authority’s Manager to the respective Agencies’ Directors, are hereby authorized to act as enforcement
agents of each of their respective agencies with respect to regulations consistent herewith adopted said
by Agencies in accordance with the provisions of Section 6.14 hereinafter.
SECTION 6.2. UNAUTHORIZED DISCHARGES.
SECTION 6.2.1. NOTIFICATION. Every user shall notify Authority’s Manager immediately
upon discharging wastes or wastewater in violation of the provisions of these regulations, or any permit
issued pursuant to these regulations. A user who discharges, causes to be discharged, or permits to be
discharged such wastes or wastewater shall, within 15 days of the occurrence thereof, submit a written
report to Authority’s Manager describing the cause or causes of such unauthorized discharge, and
measures taken, or proposed to be taken, to prevent future similar occurrences. Such report shall not
relieve any user of liability for any expense, loss, or damage suffered or incurred by an Agency or the
Authority, directly or indirectly, by reason of such unauthorized discharge. Such report shall not relieve
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or absolve any person from civil liabilities, or imposition of civil or criminal penalties in any manner
whatsoever.
SECTION 6.2.2. NOTICES TO EMPLOYEES. Every non-domestic user, every user issued a
mandatory wastewater discharge permit pursuant to Section 4.2, and every user issued a discretionary
wastewater discharge permit pursuant to Section 4.3 shall prominently post a notice on the premises to
which the permit pertains advising of the requirement to notify Authority’s Manager of any
unauthorized discharge, including the telephone number of Authority’s Manager to be called in the
event of such discharge. Authority’s Manager may require any user to inform and advise his or her
officers, agents, and employees of any particular provisions of these regulations, any permit issued
pursuant to these regulations, or other requirements of law, or of any other information which may be of
assistance in ensuring compliance with these regulations, such permit, or other requirements of law.
SECTION 6.3. CEASE AND DESIST ORDERS. Upon a determination by Authority’s
Manager that a discharge of waste or wastewater has occurred, or is occurring, or is about to occur in
violation of any provision of these regulations, or of any provision of any permit issued pursuant to these
regulations, Authority’s Manager may issue an order to cease and desist such discharge, or practice, or
operation likely to cause such discharge, and further order such person to:
(a) Comply forthwith with the provisions of these regulations, or the provisions of any
permit issued pursuant to these regulations;
(b) Comply in accordance with a time schedule established by Authority’s Manager; and/or
(c) Take appropriate remedial or preventive action.
SECTION 6.4. TIME SCHEDULES. Upon a determination by Authority’s Manager that a
discharge of waste or wastewater has occurred, or is occurring, or is about to occur in violation of the
provisions of these regulations, or in violation of any provision of a permit issued pursuant to these
regulations, Authority’s Manager may require the person or user having so discharged, or discharging,
or about to discharge, to submit for approval, subject to such modifications, terms and conditions as
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Authority’s Manager reasonably deems necessary or appropriate, a detailed time schedule of specific
actions which the person or user shall take in order to eliminate or prevent such violation or violations.
SECTION 6.5. EMERGENCY CORRECTIONS. In the event repairs, construction, or other
public work is performed on any premises pursuant to any provision of law relating to the emergency
performance of public work and the expenditure of public funds therefor, or pursuant to any other
provision of law authorizing public work on private property in order to correct, eliminate or abate a
condition upon such premises which threatens to cause, causes, or caused damage to the sewerage
facilities or which otherwise threatens to cause, causes, or caused a violation of any provision of these
regulations, or of any permit issued pursuant these regulations, or of any other requirement of law, the
user responsible for the occurrence or condition giving rise to such work, the occupant and the owner of
the premises shall be liable for such public expenditures, jointly and severally to the Authority and any
Agency or Agencies having made such expenditures.
SECTION 6.6. DAMAGES TO SEWERAGE FACILITIES. In the event damages are caused
to the sewerage facilities, or any portion thereof, by reason of a waste or wastewater discharge from any
premises in violation of the provisions of these regulations, or any permit issued pursuant to these
regulations, or of any other requirement of law, the user responsible for the occurrence or condition
giving rise to such damages, the occupant and the owner of the premises shall be liable, for the full
amount thereof, jointly and severally, to the Authority and/or any Agency or Agencies having incurred
such damages.
SECTION 6.7. EMERGENCY TERMINATION OF SERVICE. Authority’s Manager or an
Agency’s Director, as applicable, are hereby authorized and empowered immediately to terminate
sanitary sewerage service to any premises for the purpose of halting or preventing any discharge into the
sewerage facilities which the Manager or Agency’s Director, as applicable, reasonably determines to
constitute a detrimental discharge, or otherwise significantly imperils the public health, safety or
welfare. In such case, the Manager or said Agency’s Director, as applicable, shall make a reasonable
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effort to notify the user and/or the owner of the premises prior to halting or preventing such discharge;
provided, however, that the failure of the user or owner to receive such notice shall not affect any action
taken hereunder, so long as the determination of detrimental discharge or imperilment of the public
health, safety or welfare made by Authority’s Manager or said Agency’s Director, as applicable, was
reasonable and made in good faith.
In the event that the Manager or an Agency’s Director, as the case may be, terminates sanitary
sewerage service to any premises pursuant to the provisions of this section, the Manager or said
Agency’s Director, shall notify the user and the owner and occupant of the premises (if such persons are
not the same as the user) that sanitary sewerage service has been terminated, and shall provide said user,
owner or occupant an opportunity to be heard on the matter of termination not more than ten (10) days
following such termination. Notice of such hearing shall be given in the manner provided for giving
notices of violation pursuant to Section 6.9 and such hearing shall be conducted in the manner provided
for enforcement hearings pursuant to Section 6.10. Appeals from the determination of Authority’s
Manager may be taken in the manner provided for appeals pursuant to Section 6.11.
SECTION 6.8. PERMIT REVOCATION. Authority’s Manager may revoke, after a hearing on
the question of revocation, any permit issued pursuant to the provisions of these regulations upon a
determination by him or her that:
(a) The permittee has failed to report factually the wastewater constituents, characteristics, or volume of the permitted wastewater discharge;
(b) The permittee has failed to report significant or substantial changes in the operations
conducted upon the premises to which the permit pertains, or significant or substantial changes in wastewater constituents, characteristics, or volumes pertaining to said premises;
(c) The permittee has refused, or failed to permit, reasonable access to the premises to which
the permit pertains; or
(d) The permittee has violated, caused to be violated, or permitted to be violated, any term, condition, or provision of the permit.
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In the event that Authority’s Manager preliminarily determines that a permit should be revoked
for any of the foregoing reasons, he or she shall notify the permittee and the owner and occupant of the
premises (if such persons are not the same as the user) to which the permit pertains of a hearing on the
question of revocation. Notice of such hearing shall be given in the manner provided for giving notices
of violation pursuant to Section 6.9 and such hearing shall be conducted in the manner provided for
enforcement hearings pursuant to Section 6.10. Appeals from the determination of Authority’s Manager
may be taken in the manner provided for appeals pursuant to Section 6.11.
SECTION 6.9. NOTICE OF VIOLATION. Whenever Authority’s Manager or an Agency's
Director of the Agency within the boundaries of which a user’s premises is located finds that any such
user has violated or is threatening to violate any provision or requirement of these regulations, or any
provision or requirement of any permit issued pursuant to these regulations, or any prohibition,
limitation, or requirement of law, Authority’s Manager, or said Agency’s Director, as the case may be,
shall serve upon such user written notice stating the nature of the violation, ordering cessation thereof
and directing submittal of a written explanation of the cause of the violation. Service of such notice shall
be made personally or by certified or registered mail (return receipt requested), addressed to the
premises which is the source or location of such violation, the address of the user or permittee
theretofore specified by said user or permittee to Authority’s Manager or said Agency’s Director (if
different than the address of the premises) and also to the owner of said premises as shown on the last
equalized assessment roll prepared by the County Assessor, County of San Mateo. Within 30 days of the
date of said notice, the user, permittee, and/or owner of the premises shall submit to Authority’s
Manager (with a copy to said Agency’s Director) a written explanation of the cause of such violation.
SECTION 6.10 ENFORCEMENT HEARING.
SECTION 6.10.1. HEARING. Authority’s Manager may order any user who causes or allows
an unauthorized discharge to enter the sewerage facilities or who has otherwise violated, or is
threatening to violate, any provision or requirement of these regulations, or any provision or
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requirement of any permit issued pursuant to these regulations, or any prohibition, limitation or
requirement of law, to show cause before him or her why a proposed enforcement action should not be
taken. Notice of a hearing thereon shall be served on the user and/or permittee (if such violation
pertains to a permit issued pursuant to these regulations) specifying the time, place and date of the
hearing, the nature of the violation of these regulations or of any permit issued pursuant to these
regulations or of any other requirement of law giving rise to the enforcement proceedings, a proposed
enforcement action or actions and directing the user to show cause before Authority’s Manager why the
proposed enforcement action should not be taken. Said notice may be combined with a notice of
violation issued pursuant to Section 6.9.
Notice of the hearing shall be served personally or by certified mail (return receipt requested)
addressed, in the case of a user or permittee, to the premises where the alleged violation has taken, or is
taking place, to the address theretofore specified by said user or permittee to Authority’s Manager or
said Agency’s Director (if different than the address of the premises) and also to the owner of said
premises as shown on the last equalized assessment roll prepared by the County Assessor, County of
San Mateo. Said hearing shall be held within 60 days following the date of service of the notice.
SECTION 6.10.2. PROCEDURE. At the hearing the user and/or permittee, the owner of the
premises above—mentioned, and the Agency’s Director of the Agency within the boundaries of which
the premises is located shall be given the opportunity to be heard. Formal rules of evidence shall not be
applicable, provided however, that oral and documentary evidence shall be received by Authority’s
Manager relevant to the issue being heard.
A verbatim transcript of the record need not be prepared; provided, however, that if the user,
permittee, or owner of the premises requests a transcript, the Authority shall cause a transcript to be
prepared; provided, further, that the cost of preparing such transcript shall be borne by the party
requesting it. A request for the preparation of a transcript shall be made not less than five (5) business
days prior to the hearing. The requesting party shall deposit with Authority’s Manager the estimated
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cost of providing a transcript prior to commencement of the hearing. Failure to deposit the estimated
cost shall be deemed a waiver of the request, and in such instance the Authority shall not be required to
provide a transcript. The notice of hearing shall contain notification of the requirements hereof relating
to the preparation of a transcript.
SECTION 6.10.3. DECISION. Upon completion of the hearing, and upon a finding by
Authority’s Manager that a violation of these regulations or of any permit issued pursuant to these
regulations or any other requirement of law has occurred, Authority’s Manager may issue an order to
the user, permittee, or owner of the premises to which the violation pertains, who or which Authority’s
Manager finds responsible for said violation, directing that, following a specified time period, sewerage
service shall be discontinued, and/or the permit with respect to which the violation occurred shall be
revoked unless (i) adequate treatment facilities, devices or other related appurtenances shall have been
installed or used in conjunction with existing treatment facilities, devices or other related
appurtenances, or (ii) existing treatment facilities, devices or related appurtenances are properly
operated, maintained or repaired, or (iii) other appropriate remedial action specified by Authority’s
Manager shall have been taken. Authority’s Manager may issue such other orders and directives as are
necessary or appropriate to obtain compliance with the provisions of these regulations, any permit
issued pursuant to these regulations or any other requirement of law.
SECTION 6.11. APPEALS.
SECTION 6.11.1. RIGHT TO APPEAL. Any user, permittee, applicant, or owner of premises
aggrieved by the determination of Authority’s Manager may appeal such determination to Authority’s
Commission by filing a written notice of appeal with Authority’s Manager within 30 days of the date of
said Manager’s determination. The notice of appeal shall set forth the facts and reasons supporting the
appeal. Hearing on the appeal shall be held by Authority’s Commission within 60 days from the date of
filing the notice of appeal. Notice of the date, time and place of the hearing on the appeal shall be given
in the manner specified for hearings under Section 6.10.1 and shall include notice of the appellant’s
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right to preparation of a transcript of the appeal hearing upon request therefor and depositing the
estimated cost thereof in the manner provided under Section 6.10.2.
SECTION 6.11.2. PROCEDURE. Hearing on the appeal by Authority’s Commission, shall be
conducted in the manner provided for enforcement hearings specified in Section 6.10.2, including,
without limitation, the provisions relating to preparation of a transcript of the hearing.
SECTION 6.11.3. DECISION. Upon conclusion of the hearing, Authority’s Commission may
affirm, reverse or modify the determination of Authority’s Manager as the Commission deems just and
equitable, and in furtherance of the provisions, purposes and intent of these regulations. During the
pendancy of any such appeal, the determination of Authority’s Manager shall remain in full force and
effect. The determination of Authority’s Commission on the appeal shall be final.
SECTION 6.12. PUBLIC NUISANCE. Any discharge, or threatened discharge, or any
condition which is in any manner in violation of the provisions of these regulations, or of any permit, or
any order or directive of Authority’s Manager issued or made pursuant to these regulations, shall be, and
the same is hereby declared to be a public nuisance. Such nuisance may be abated, removed, or
enjoined, and damages assessed therefor, in any manner provided by law.
SECTION 6.13. CIVIL ASSESSMENTS. Any user, permittee, or owner of premises or other
person who or which violates any requirement of these regulations, or of any permit, directive, or order
issued or made pursuant to these regulations requiring pretreatment of any industrial waste which would
otherwise be detrimental to the sewerage facilities or their proper and efficient operation and
maintenance, the health and safety of the employees of the Authority or the environment or which
requires the prevention of the entry of such waste into the sewerage facilities, may be civilly liable
pursuant to the provisions of California Government Code Sections 54740 or 54740.5. The Authority’s
Manager is hereby authorized to issue administrative complaints pursuant to Government Code Section
54740.5. (Amended, Res. SVCW No. 05-39, 06/14/05)
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SECTION 6.14. AGENCY’S REGULATIONS. Pursuant to the provisions of the Joint
Exercise of Powers Agreement referenced in Section 1.3.4, each Agency shall enact an ordinance,
uniform in content with these regulations; provided, however, that in addition to the enforcement
provisions herein contained, each such ordinance shall include provisions to the effect that any person
violating or causing the violation of any provision of such ordinance or of any permit issued pursuant to
these regulations or otherwise issued by Authority’s Manager, shall be guilty of a misdemeanor, and
upon conviction thereof, shall be punishable by a fine of not more than One Thousand Dollars
($1,000.00), or by imprisonment in the County jail for a term not exceeding six months, or by both such
fine and imprisonment, and that every day such violation shall continue shall constitute a separate
offense. Nothing in this section, or these regulations, contained shall be deemed a limitation upon any
Agency to enact regulations pertaining to said Agency’s portion of the sewerage facilities, or otherwise
pertaining to the sewerage facilities, not inconsistent with the provisions of these regulations. Said
Agency regulations shall also vest Authority’s Manager and Authority’s Commission with the powers,
functions and authority granted to them, respectively, pursuant to these regulations.
SECTION 6.15. AUTHORITY’S DISCRETION. Authority, or Authority’s Manager, as the
enforcing agent or officer so designated by each of the Agencies’ regulations adopted pursuant to
Section 6.14 hereof, and as empowered and vested with the authority and functions correspondingly
herein provided, shall have, and are hereby granted, the discretion to proceed with enforcement actions
pursuant to either said Agencies’ regulations or these regulations in any particular instance.
SECTION 6.16. REMEDIES CUMULATIVE. The remedies provided for in these regulations
shall be cumulative and not exclusive, and shall be in addition to any and all other remedies available to
Authority in the exercise of its powers.
SECTION 6.17. SEVERABILITY. If any provision of these regulations or the application
thereof to any person is held invalid, such invalidity shall not affect any other provision or application of
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these regulations which can be given effect without the invalid provision or application, and to this end
the provisions of these regulations are severable.
S:\Discharges_ Non-routine & Low Volume\Non Routine Discharges\Non Routine Discharge Applications\Non-Routine Discharge Application SVCW email version.docx..ver. 6/27/05 Page 1 of 3
IMPORTANT NOTICE TO DISCHARGERS You have contacted Silicon Valley Clean Water (SVCW) regarding the discharge of liquid waste into the sanitary sewers. Be advised that it is illegal to discharge hazardous waste into the sanitary sewers. It is the responsibility of your company to determine whether the liquid waste is classified as a hazardous waste; SVCW does not make this determination. To help with this evaluation you should contact your facility’s Environmental Health and Safety staff, a private consultant, or San Mateo County Environmental Health at (650) 363-4305. Once the waste is determined to be non-hazardous, SVCW will evaluate the waste for acceptance into the sanitary sewers. Complete the attached form and fax to SVCW. The review process typically takes 1-3 days and the results will be returned to you by fax. You should be aware that many non-hazardous wastes may impact the SVCW treatment processes. Our treatment facility was designed to treat a limited range of pollutants found in residential wastewater. We encourage you to pursue any available reuse or recycle options before considering discharge to the sanitary sewers.
SVCW NON-ROUTINE DISCHARGE APPLICATION File # 70-60.01
Person Requesting: Phone No.
Company: Fax No.:
Affected Business: Assessors Parcel No.:
Address: City: Zip:
Waste Description:
Constituents in Wastewater: Concentration: Units:
Volume to Discharge (gal):
Date of Discharge: Preferred Time of Discharge:
Preferred Discharge Method:
Exact location, description and address of sanitary sewer discharge point:
Comments:
Waste Certification: I certify that the information above is true and complete to the best of my knowledge. I certify that the proposed discharge is not a hazardous waste. I understand that it is illegal to discharge hazardous waste to the sanitary sewers. Signed: __________________________ Title: ____________________ Date: __________ Submit Application to: Silicon Valley Clean Water Environmental Services Division Phone: (650) 591-7121 1400 Radio Road E-Mail [email protected] Redwood City, CA 94065
PAGE 1 OF 2 (Page 1 to be completed by Discharger; page 2 to be completed by SVCW)
Received at SVCW: Date: ______________ Time: _____________ By: ________________
SVCW NON-ROUTINE DISCHARGE APPLICATION File # 70-60.01
PAGE 2 OF 2 (Page 2 to be completed by SVCW)
Expected Impact of Discharge:
Collection System:
SVCW Pump Station:
SVCW Plant Processes:
SVCW Effluent Quality:
SVCW Sludge Quality:
Air Quality & Odors:
Work Health & Safety:
Additional Discussion:
SVCW Authorization: Discharge Approved Not Approved
Signature _________________________________ Date: _____________________
Allowable Flow Rate: gallons/day gallons/minute
Total Discharge Allowed: gallons
Time of Discharge: Time/Date Start: Time/Date Stop: ____
Other Conditions:
This authorization applies only to the material described on Page 1. The discharge of hazardous waste is not allowed. The discharge must be in compliance with the SVCW Regulations and any applicable provisions of Federal, State, or local regulations.
Sanitary Sewer District/City Authorization:
Date Application Received: DISTRICT USE:
Local Authorization Required? Yes No PERMIT #:
Discharge Approved: PERMIT FEE: $
Discharge NOT Approved: SAMPLING & MONITORING: $
By: Date: TOTAL FEES: $
Title: INVOICE #:
District/City: DATE FEES PAID: * * * FEES MUST BE PAID PRIOR TO DISCHARGE * * *
Additional Discussion/Conditions:
IMPORTANT NOTICE TO DISCHARGERS
You have contacted Silicon Valley Clean Water (SVCW) regarding the discharge of liquid waste
into the sanitary sewers. Be advised that it is illegal to discharge hazardous waste into the
sanitary sewers. It is the responsibility of your company to determine whether the liquid
waste is classified as a hazardous waste; SVCW does not make this determination. To help
with this evaluation you should contact your facility’s Environmental Health and Safety staff, a
private consultant, or San Mateo County Environmental Health at (650) 363-4305.
Once the waste is determined to be non-hazardous, SVCW will evaluate the waste for acceptance
into the sanitary sewers. Complete the attached form and fax to SVCW. The review process
typically takes 1-3 days and the results will be returned to you by fax.
You should be aware that many non-hazardous wastes may impact the SVCW treatment
processes. Our treatment facility was designed to treat a limited range of pollutants found in
residential wastewater. We encourage you to pursue any available reuse or recycle options
before considering discharge to the sanitary sewers.
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SVCW LOW VOLUME DISCHARGE AUTHORIZATION FORM File # 70-60.02
INFORMATION TO BE COMPLETED BY DISCHARGER
Name of Discharger:
Address of Discharger:
City: Zip:
Person to Contact for More Information:
Phone: Fax:
Description, Source of Wastewater and Pollutants:
Discharge volume expected per day: Maximum _____ gallons; Average _____ gallons
Discharge Frequency/Period: __________
Is this waste a hazardous waste under federal or state law? YES NO
Is the volume of process wastewater from all manufacturing at this site less than 1000 gallons per
day? YES NO
Waste Certification: I certify that the information above is true and complete to the best of my knowledge. I certify that the proposed discharge is not a hazardous waste. I understand that it is illegal to discharge hazardous waste to the sanitary sewers. Signed _________________________Title _________________________ Date ____________
_________________________ (print name if different than person to contact above)
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SVCW LOW VOLUME DISCHARGE AUTHORIZATION FORM File # 70-60.02
REVIEW AND AUTHORIZATION TO BE COMPLETED BY SVCW
Expected Impact of Discharge
Collection System:
Pump Station:
SVCW Plant Processes:
Effluent Quality:
Sludge Quality:
Air Quality / Odors:
Worker Health & Safety:
Additional Discussion:
Discharge Authorization The discharge described above is allowed is not allowed
Maximum allowable flowrate: _____ gallons/day; _____ gallons/minute
Signed _________________________Title _________________________ Date ____________
Other conditions:
This authorization applies only to the discharge described above. This authorization will remain in effect for 5 years; the discharger must reapply in order to renew this authorization. The discharger must contact SVCW if there is an increase in discharge volume or pollutant concentration. The discharge of hazardous waste is not allowed. The discharge must be in compliance with the SVCW Regulations and any applicable provisions of Federal, State or local regulations.
Silicon Valley Clean Water – Environmental Services Division Phone (650) 591-7121 1400 Radio Road E-Mail [email protected] Redwood City, CA 94065 form version 4/26/05
AppendixC
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SP9
SP8SP7
SP5
SP4
SP3
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SP10
Path: L:\Acad 2000 Files\20000\20171-15\GIS\ArcMap\FigX_Delin_20150528.mxd
Study Area - 17.96 acres
Waters - 0.06 acre
Wetland - 3.99 acres
Sample Point
Map Prepared Date: 5/28/2015Map Prepared By: dchanBase Source: ESRI World Imagery (2010)Data Source(s): WRA
Figure X. DRAFT Delineation Map
SVCW Airport Staging AreaSan Mateo County, California
.0 100 20050
Feet