LYONS, GA NORTH WWTP UPGRADE & EXPANSION Advertisement... · Lyons, GA North WWTP DDR H&A T.O.C. iv...

DESIGN DEVELOPMENT REPORT

FOR THE

LYONS, GA NORTH WWTP

UPGRADE & EXPANSION

FROM

0.670 MGD EXTENDED AERATION

TO

1.5 MGD BIOLOGICAL NUTRIENT REMOVAL

AUGUST, 2016

Lyons, GA North WWTP DDR H&A

T.O.C. i

Table of Contents

1 Introduction ...................................................................................................................................... 1- 1

1.1 Description of Project ............................................................................................................... 1- 1

1.2 Record of Alternative Selection ................................................................................................ 1- 1

2 Existing Sewer System ....................................................................................................................... 2- 1

2.1 Wastewater Treatment Capacity .............................................................................................. 2- 1

2.2 Sanitary Sewer Collection System ............................................................................................. 2- 1

2.3 North WWTP Existing Process Flow Scheme ............................................................................ 2- 2

2.4 Performance of North Wastewater Treatment Plant ............................................................... 2- 2

3 Design Criteria ................................................................................................................................... 3- 1

3.1 Design Influent Loadings ........................................................................................................... 3- 1

3.2 Wasteload Allocation ................................................................................................................ 3- 2

4 Process Flow Scheme and Components ........................................................................................... 4- 1

4.1 Liquid Train Processes ............................................................................................................... 4- 1

4.1.1 System Improvements ...................................................................................................... 4- 1

4.1.2 Influent Screen .................................................................................................................. 4- 3

4.1.3 Influent Lift Station ........................................................................................................... 4- 5

4.1.4 Influent Splitter Box ........................................................................................................ 4- 20

4.1.5 Biological Treatment System .......................................................................................... 4- 23

4.1.6 Secondary Clarifiers ........................................................................................................ 4- 29

4.1.7 Surface Filtration ............................................................................................................. 4- 35

4.1.8 UV Disinfection................................................................................................................ 4- 38

4.1.9 Flow Measurement Weir (Combination Structure) ........................................................ 4- 39

4.1.10 Effluent Cascade .............................................................................................................. 4- 40

4.1.11 Outfall Pipe ...................................................................................................................... 4- 46

4.2 Chemical Feed Processes ........................................................................................................ 4- 48

4.2.1 Coagulation (Alum) ......................................................................................................... 4- 48

4.2.2 pH Adjustment (Soda Ash) .............................................................................................. 4- 49

4.3 Solids Handling Processes ....................................................................................................... 4- 52


T.O.C. ii

4.3.1 Activated Sludge Pumps .................................................................................................. 4- 52

4.3.2 Digester Splitter Box ....................................................................................................... 4- 53

4.3.3 Aerobic Digestion ............................................................................................................ 4- 53

4.3.4 Sludge Transfer Lift Station ............................................................................................. 4- 62

4.3.5 Sludge Handling Facility .................................................................................................. 4- 63

4.3.6 Sludge Drying Beds .......................................................................................................... 4- 64

4.4 Side Stream Processes ............................................................................................................ 4- 65

4.4.1 Water Reuse System ....................................................................................................... 4- 65

4.4.2 Overflow Pond ................................................................................................................ 4- 67

4.4.3 Pond Withdrawal Station ................................................................................................ 4- 67

5 Buildings ............................................................................................................................................ 5- 1

5.1 Convert Existing Control Building into Operations Building ..................................................... 5- 1

5.2 New Control Building ................................................................................................................ 5- 1

6 Phased Construction ......................................................................................................................... 6- 1

7 Points of Compliance ........................................................................................................................ 7- 1

8 Standby Power .................................................................................................................................. 8- 1


T.O.C. iii

List of Appendices

Appendix No. Description

I East WWTP NPDES Permit No. GA0033405

II North WWTP NPDES Permit No. GA0033391

III Georgia EPD Wasteload Allocation – June 27, 2016

IV Influent Screen Concept

V EVOQUA Concept and Calculations (Train 1 & Train 2)

VI Treatment Design Calculations

VII UV System Concept

VIII Typical Belt Press Brochure

IX Chemical Oxygen Demand Fractions of Municipal Wastewater for

Modeling of Wastewater Treatment

Referenced Exhibits

Exhibit No. Description Referenced in

Section

1

"Engineering Report Evaluation for Sanitary Sewer System & System-Wide Wastewater Treatment Capacity Upgrades" by

Hofstadter and Associates, Inc. (Rev. June, 2013) 1.2

2 "Hydraulic Handbook" (1988) by Fairbanks Morse Pump

Corporation

4.1.4

4.1.9

4.1.10

3 "Wastewater Engineering - Treatment and Reuse" (Fourth Edition)

by Metcalf & Eddy

4.1.5

4.1.7

4.2.2

4 "Wastewater Engineering - Treatment, Disposal, and Reuse"

(Third Edition) by Metcalf & Eddy

4.1.5

4.1.8

4.2.2

4.3.3

5 "Recommended Standards for Wastewater Facilities" (2004

Edition), commonly known as: "Ten States Standards"

4.1.6

4.1.7

4.3.3

6 "Wastewter Treatment Plant, WPCF Manual of Practice No. 8"

(Second Printing, 1982) by Water Pollution Control Federation

4.1.10

4.2.1

7 "Environmental Engineering" by Peavy / Rowe / Tchobanoglous 4.1.10

8 "Phosphorus Removal from Wastewater" (1990) by Bowker and

Stensel 4.2.1

9 "Process Design Manual - Land Application of Sewage Sludge

and Domestic Sludge" (September, 1995) by EPA 4.3.3


T.O.C. iv

List of Tables

Table No. Description Page No.

2-01 Existing Sewage Lift Stations 2-2

2-02 Treatment Performance for North WWTP (June, 2011 - May, 2012) 2-3

3-01 WWTP Design Loadings 3-1

3-02 Georgia EPD Wasteload Allocation Limits 3-2

4-01 Feeder Gravity Main Calculations 4-2

4-02 Influent Force Main Selection Chart 4-10

4-03 Influent Splitter Box Weir Flow Split Chart 4-22

4-04 Typical Design Ranges for 5-Stage Bardenpho Process 4-24

4-05 Biological Nutrient Removal Treatment Design Summary 4-26

4-06 Secondary Clarifier Design Criteria 4-29

4-07 Secondary Clarifier Design Loadings 4-30

4-08 Secondary Clarifier Calculations 4-32

4-09 Secondary Clarifier Design Selection 4-33

4-10 Secondary Clarifier Performance Verification 4-34

4-11 Filter Design Loadings 4-35

4-12 Typical Cloth Media Disk Filter Design Parameters 4-36

4-13 Filter Design Calculations 4-36

4-14 UV System Performance Characteristics 4-38

4-15 Summary of UV Equipment 4-39

4-16 Outfall Pipe Calculations 4-47

4-17 Typical Alkalinity Strength 4-49

4-18 Summary of RAS Pumps 4-52

4-19 Typical Sludge Characteristics 4-55

4-20 Digester Tank Preliminary Design Summary 4-62

4-21 Belt Filter Press Design Calculations 4-63

4-22 Belt Filter Press Typical Performance Characteristics 4-64

4-23 Preliminary Estimate of Reuse Water Demand Flow 4-65

List of Figures

Figure No. Description Follows Page No.

4-01 Proposed WWTP Upgrades - Plan 4-1

4-02 Proposed WWTP Upgrades - Hydraulic Grade Line 4-1

4-03 Biological Nutrient Removal Process Schematic 4-24


Introduction 1- 1

1 Introduction The City of Lyons has requested the firm of Hofstadter and Associates, Inc. (H&A) to prepare a

Design Development Report (DDR) to upgrade the existing North wastewater treatment plant

(WWTP) by expanding capacity from 0.67 mgd to 1.5 mgd, and by converting the treatment process

from an extended aeration plant to a 5-stage biological nutrient removal plant.

The Lyons East WWTP will be repaired as a separate project after the North WWTP upgrade

project is complete.

1.1 Description of Project The existing North WWTP will remain in service during the upgrade construction project, so

construction phasing considerations will be important, as described in a later chapter of this DDR.

To upgrade both the capacity and the treatment capability of the facility, some existing unit

processes and components will remain in place (i.e., effluent cascade), some will be converted to

other uses (i.e., existing 0.67 mgd treatment tank becomes a 0.400 mgd 5-stage treatment tank),

and some will be abandoned (i.e., influent pump station).

In addition, certain new components will be constructed. Individual components are described

in greater detail in later chapters.

1.2 Record of Alternative Selection In the 1980s, the City of Lyons, Georgia contracted to simultaneously construct the East (0.67

mgd) WWTP and the North (0.67 mgd) WWTP. These facilities entered service in approximately

August, 1988, and they initially served the residents and other institutions well. The available

treatment capacity allowed Lyons and Toombs County to develop an industrial park in the mid-

2000s in order to recruit industry and jobs to the region. They successfully recruited different

industries, including Chicken-of-the-Sea (C-o-S), which is a tuna canning facility.

With the success of recruiting industry to the city came certain negative impacts to the North

WWTP, including higher-than-historical wastewater loadings, the introduction of FOG (fats-oils-

grease), and the variation of flow rates resulting from the C-o-S 4-day work week. Thus, the Lyons

City Council requested that Hofstadter & Associates, Inc. analyze various alternatives for upgrading

the system-wide wastewater treatment capacity. Many concepts were developed, and planning-

level costs were generated. These concepts are described in the July, 2012 H&A report titled

“Engineering Report Evaluation for Sanitary Sewer System & System-Wide Wastewater

Treatment Capacity Upgrades for the City of Lyons, Georgia” (current version dated June, 2013).

Examples of the concepts considered in the report included:


Introduction 1- 2

Do Nothing

Rehabilitate the existing WWTPs

Upgrade the existing WWTPs

o Expand capacity

o Convert treatment process from extended aeration to biological nutrient removal

Add new treatment components

Discharge treated effluent to a new land application system (LAS)

Discharge to the Altamaha River

Abandon existing WWTPs and consolidate into a new facility

o Combined Complete-Mix Aerated Pond WWTP

o Combined Biological Nutrient Removal WWTP

Repair existing WWTPs

Etc.

Between 2012 and 2016, the Lyons City Council and City Staff sought funding for the estimated

project costs. Different funding sources were considered, such as:

Contributing local funds

o City reserve account funds

o Toombs County backing of bonds

Private bonds

GEFA loans

Etc.

Meanwhile, concept costs continued to be developed, with the primary focus being on the

North WWTP since it was most overloaded, and because it serves the sanitary sewer basin which

includes the industrial park. The City Council judged that the East WWTP rehabilitation was not as

high of a priority at the present time. By Spring, 2016 H&A recommended that the North WWTP

capacity be expanded to 1.5 mgd. The two (2) main North WWTP upgrade alternatives consisted of

a DAVCO 5-Stage BNR WWTP vs. an EIMCO 3- to 5- Stage BNR WWTP.

In Spring, 2016 the Lyons City Council took a tour of the Eastman, Georgia 1.8 mgd EIMCO

“Carrousel” biological nutrient removal WWTP in order to contrast that type of concept with the

City’s existing extended aeration facility. Following the tour, City Staff, based upon a feel of the

council’s desires, indicated that the lowest capital cost concept currently under consideration

should be developed further. Thus, this Design Development Report is based on the DAVCO 5-

Stage BNR WWTP per the lower estimated construction cost. Based on a present worth cost

analysis, DAVCO’s higher operating and equipment replacement costs are not enough to change

the selection from the DAVCO process to the EIMCO process.


Existing Sewer System 2- 1

2 Existing Sewer System Municipal sewer systems have two major components: 1) treatment and discharge capacity,

and 2) collection system capacity. These components are described in greater detail in the

following sections.

2.1 Wastewater Treatment Capacity The City of Lyons operates two separate publically owned treatment works (POTW) facilities,

both of which are permitted to discharge 0.670 million gallons per day (mgd). The East WWTP is

authorized under NPDES Permit No. GA0033405 (see Appendix I) to discharge to an un-named

tributary to Pendleton Creek, which is tributary to the Ohoopee River, which is tributary to the

Altamaha River. The North WWTP is authorized under NPDES Permit No. GA0033391 (see

Appendix II) to discharge to Swift Creek, which is tributary to Pendleton Creek, which is tributary to

the Ohoopee River, which is tributary to the Altamaha River. Both facilities, which are Smith &

Loveless extended aeration package plants, were constructed in 1988. The city’s total permitted

treatment capacity is 1.34 mgd.

The remainder of this Design Development Report details the upgrade and expansion of the

North WWTP from 0.670 mgd to 1.500 mgd. Following completion of the upgrade and expansion,

total city treatment capacity will be 2.17 mgd.

2.2 Sanitary Sewer Collection System The City of Lyons serves 1,605 sewer customers. Sanitary sewer system gravity mains generally

follow the city’s topography. The Central of Georgia Railroad travels east-and-west through the

middle of town along a ridge line. Most gravity lines south of the railroad drain towards the Lyons

East WWTP, while most gravity lines north of the railroad drain towards the Lyons North WWTP.

There are 13 lift stations in the system, plus a station in the city of Santa Claus, that lift sewage

where necessary. Lift station data is presented in the table below.



Table 2-01

Existing Sewage Lift Stations

LS No. Location Date Installed Pump Data

1 N. State & W. Peterson Ave. unknown 2- 422 gpm

2 Stewart Lane unknown unknown

3 Hilton Dr. & Cascade Ave. unknown unknown

4 Pine Ridge Dr. unknown unknown

5 E. Clifton Ave. unknown unknown

6 Maple St. & US Hwy 280 unknown unknown

7 Belvue Ave. unknown unknown

8 N. Gwinnett St. unknown unknown

9 McLendon Trailer Park unknown unknown

10 North Treatment Plant 1989 2- 465 gpm

11 East Treatment Plant 1989 2- 465 gpm

12 Solomon unknown 2- 100 gpm

13 US Hwy 1 North 2001 2- 250 gpm

SC-1 City of Santa Claus 2012 2- 100 gpm

2.3 North WWTP Existing Process Flow Scheme The existing process flow scheme for the North WWTP is listed below.

Liquid Train Processes

1) Influent manual screening

2) Flow equalization pond

3) Feeder pump station

4) Extended aeration basins (dual compartments with parallel flow)

5) Secondary clarifier

6) Chlorine contact chamber

7) Flow measurement weir

8) Aeration cascade

9) Outfall pipe

Solids Handling Processes

1) Air lift sludge pump (for RAS and WAS)

2) Aerobic digester

3) Sludge drying beds

2.4 Performance of North Wastewater Treatment Plant Since this Design Development Report is prepared for the upgrade and expansion of the North

WWTP, the performance for this facility during a previous year is shown in the following table.



TABLE 2-02

TREATMENT PERFORMANCE FOR NORTH WWTP (June, 2011 – May, 2012)

Month Flow Influent BOD5

Effluent BOD5

Influent TSS

Effluent TSS

Effluent Ammonia,

as N

Effluent Fecal

Coliform * Effluent

TRC

Units: (mgd) (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (# / 100 ml) (mg/l)

Permit Limits (Jan.): 0.670 --- 10 --- 30 6.5 200 Report

Permit Limits (Feb. - Mar.): 0.670 --- 15 --- 30 8.7 200 Report

Permit Limits (April): 0.670 --- 10 --- 30 3.5 200 Report

Permit Limits (May): 0.670 --- 7.5 --- 30 2 200 Report

Permit Limits (June - Sept.): 0.670 --- 5 --- 30 1 200 Report

Permit Limits (Oct.): 0.670 --- 7.5 --- 30 1.5 200 Report

Permit Limits (Nov.): 0.670 --- 7.5 --- 30 2.5 200 Report

Permit Limits (Dec.): 0.670 --- 10 --- 30 5 200 Report

June, 2011 0.4402 191 19.9 198 32 1.08 133 0.89

July, 2011 0.3917 171 10.4 164 15 0.80 95 0.90

August, 2011 0.4000 500 12.3 1567 13.5 1.34 209 0.72

September, 2011 0.5133 183 10.4 112 11 0.56 8 0.70

October, 2011 0.4636 181 10.7 160 15 0.80 2 0.64

November, 2011 0.4983 124 5.3 87 6.3 0.71 2 0.56

December, 2011 0.3789 136 3.8 99 4.9 0.69 14 0.52

January, 2012 0.2455 84.8 86 96 9.8 0.96 9 0.48

February, 2012 0.2982 157 4.2 129 6.4 0.80 10 0.55

March, 2012 0.4619 181 3.8 134 4.4 0.88 2 0.70

April, 2012 0.3224 178 5.4 179 4.3 1.10 2 0.76

May, 2012 0.3631 169 5.9 148 4.4 0.75 2 0.75

Average of Monthly Avg. 0.3981 188.0 14.8 256.1 10.6 0.87 10 0.68

NOTE: August, 2011 includes a Chicken-of-Sea shock load of 14,250 mg/l TSS and 500 mg/l BOD5 on 8/17/11 NOTE: Bold italics represent permit violations.

* geometric mean


Design Criteria 3- 1

3 Design Criteria The proposed project consists of upgrading the existing North wastewater treatment facility

from an extended aeration plant to a biological nutrient removal plant. In addition the project will

expand the plant’s treatment capacity from 0.67 mgd to 1.5 mgd. Design influent and effluent

loadings are shown in the remainder of this chapter.

3.1 Design Influent Loadings The design influent loadings will be for typical full-strength domestic sewage for 5 reasons:

1) The design is conservative and can provide operator flexibility.

2) The City will be able to identify and correct inflow/infiltration flows into the existing sewer

system, which will increase loading concentrations by lowering dilution.

3) Future sewer system expansions will be constructed with newer materials which are less

susceptible to inflow/infiltration dilution.

4) Typical sewage concentration will increase over time as existing homes are remodeled with,

and new homes are constructed with, kitchen disposals and low-flow toilets, shower heads

and appliances.

5) While recruiting new industry, Lyons can offer sewer service to higher strength users.

See the following table for the design influent loadings.

Table 3-01

WWTP Design Loadings

Parameter Unit Value

Flow Avg. Flow mgd 1.50

Avg. Flow Rate gpm 1,042

Influent Peaking Factor --- 2.5

Influent Peak Flow Rate gpm 2,604

Influent Peak Flow mgd 3.75

Treatment Peaking Factor --- 2

Treatment Peak Flow Rate gpm 2,083

Treatment Peak Flow mgd 3.00

Influent Loadings

BOD5 mg/l 350

TSS mg/l 350

NH3-N mg/l 30

TKN mg/l 45

NO3-N mg/l ---

TP mg/l 10

Alkalinity (as CaCO3) mg/l 140


Design Criteria 3- 2

3.2 Wasteload Allocation The design effluent loadings are based upon the wasteload allocation limits as issued by Georgia

EPD. These limits will become the basis for the NPDES permit which will be issued prior to

construction. See Appendix III for the June 27, 2016 wasteload letter from Georgia EPD. See the

table below for a summary of the wasteload allocation limits.

Table 3-02

Georgia EPD Wasteload Allocation Limits

Constituent / Parameter (1)

Applies to Unit Limits

Effluent Flow Rate Year-round mgd 0.75 1.5

BOD5

January - April

mg/l

7.5 7.5

May - October 5.0 5.0

November - December 7.5 7.5

Total Suspended Solids Year-round mg/l 20 20

Ammonia, as N

January - April

mg/l

2.0 2.0

May - October 1.0 1.0

November - December 2.0 2.0

Total Phosphorus, as P Year-round mg/l 1.3 1.0

Dissolved Oxygen, minimum Year-round mg/l 6.0 6.0

Fecal Coliform Bacteria Year-round count / 100 ml

(geometric mean) 200 200

pH Year-round standard units 6.0 - 8.5 6.0 - 8.5

Total Residual Chlorine, maximum

(2) Year-round mg/l 0.02 0.02

Ortho-Phosphate Year-round mg/l Monitor Monitor

Nitrate-Nitrite, as N Year-round mg/l Monitor Monitor

Organic Nitrogen, as N Year-round mg/l Monitor Monitor

Total Kjeldahl Nitrogen Year-round mg/l Monitor Monitor

(1) Values are maximum monthly averages except as noted. (2) Applicable only if chlorine is used.


Process Flow Scheme & Components 4- 1

4 Process Flow Scheme and Components The proposed project will expand the capacity and upgrade the treatment capability of the

existing North WWTP from a permitted 0.67 mgd facility to a 1.5 mgd facility which discharges into

Swift Creek, which is tributary to Pendleton Creek, which is tributary to the Ohoopee River in the

Altamaha River Basin. The selected treatment process is the 5-stage biological nutrient removal

(BNR) package plant from DAVCO (Thomasville, Georgia) or similar manufacturer. The existing

treatment tank will be de-rated from 0.67 mgd to 0.400 mgd, while a 1.1 mgd sister tank will

operate in parallel.

Raw sewage influent and any overflow pond withdrawals enter the plant in a common pipe.

Between the treatment tanks and the secondary clarifiers (including RAS flows) the flow is

separated into either Train 1 (1.1 mgd train through a new structure) or Train 2 (0.400 mgd

through the converted existing structure). Following the secondary clarifiers, the flows come

together again into a common pipe until final discharge to the creek, except for a 50%/50% split

into parallel effluent cascades.

The following sections describe the proposed design. See Figure 4-01 for a plan view of the

upgrades, and see Figure 4-02 for a hydraulic profile.

4.1 Liquid Train Processes The liquid train processes consist of those components which treat the wastewater between the

influent screen and the outfall pipe. In addition, miscellaneous system improvements are shown

which transport and/or pre-treat the sewage. During these steps the raw sewage influent is

treated to clean effluent.

4.1.1 System Improvements

4.1.1.1 System Lift Station Upgrades

In the future, it will be necessary to upgrade various system lift stations in order to deliver the

increased flow to the expanded North WWTP. These lift station upgrades are not made part of the

wastewater treatment upgrade and expansion project at this time.

4.1.1.2 Dissolved Air Flotation

As budget funds become available in the future, it is recommended to construct a dissolved air

flotation system to remove fats / oils / grease (FOG), as well as grit. This component could be

constructed either upstream of the wastewater treatment plant site, or on-site between the influent

lift station and the influent splitter box. This component is not made part of the wastewater

treatment upgrade and expansion project at this time.

4.1.1.3 WWTP Feeder Gravity Main

City operators report that the existing gravity main which feeds the wastewater treatment plant

surcharges on occasion. Additional capacity is required to accommodate the expansion average

and peak flows. The replacement gravity sewer main hydraulic capacity will be designed based



upon field survey elevations. Design flow will be (1.5 mgd) x (2.5 peak factor), which is 3.75 mgd,

or 2,600 gpm.

Based on a hydraulic analysis of the existing 10-inch gravity feeder main, the pipe must be

replaced with a new 18-inch ductile iron pipe. See the calculations below for the analysis.

Pipe Capacity Formula Qcapacity = {1.49/n} * {A} * {R

^(2/3)} * {S

^(1/2)}

with,

Manning's Roughness Coefficient, (n) = varies, per pipe

material Radius, (r) = (Pipe Dia. / 2) Ft.

Area, (A) = π * r2 Ft.

2

Wetted Perimeter, (P) = 2 * π * r Ft. Hydraulic Radius, (R) = (A / P)

Hydraulic slope, S = assumed equal to

pipe gradient

Table 4-01

Feeder Gravity Main Calculations

Characteristic Unit Existing Pipe Proposed

Replacement Pipe

Average Flow

mgd 1.500 1.500

gpm 1,042 1,042

cfs 2.32 2.32

Peak Flow

mgd 3.750 3.750

gpm 2,604 2,604

cfs 5.80 5.80

Pipe gradient, sassumed % 0.50% 0.50%

Pipe status --- Existing Proposed

Pipe material --- DIP ? DIP

Manning's Roughness Coefficient, n --- 0.012 0.012

Pipe diameter in. 10 18

ft. 0.83 1.50

Pipe radius, r ft. 0.42 0.75

Area, A ft.2 0.545 1.767

Wetted perimeter, P ft. 2.62 4.71

Hydraulic radius, R ft. 0.208 0.375

Pipe capacity, Qcap cfs 1.68 8.07

gpm 755 3,621

mgd 1.088 5.214

Does pipe capacity exceed peak flow rate? --- Not Acceptable Acceptable



4.1.2 Influent Screen There will be two (2) bar screens which operate in parallel, but with each sized to handle the

average influent flow of 1.500 mgd (1,042 gpm), as well as the system’s 2.5 peak influent flow of

3.750 mgd (2,600 gpm). The primary screen will be a mechanical bar screen with an approximate

screen opening size of 3 mm. Captured screenings will be automatically removed from the screen

surface and transported to a disposal bin. The secondary screen will be a manually cleaned bar

screen with an approximate screen opening size of 0.25 inches. Captured screenings will be

removed with a rake.

The purpose of the screen is to remove grease, “rags”, trash, debris, and other large objects

from the sewage prior to entering the plant. Each screen channel will have isolation gates so that

flow can be directed to one channel, or to the other channel, or to both channels simultaneously. In

the event that a screen becomes clogged and the upstream water level rises, the overflow will

hydraulically spill into the opposite channel rather than spilling onto the ground. All captured

screenings will be collected and transported to a landfill.

Formulas Qcapacity = (1.49/n) * A * R

(2/3) * S

(1/2)

Q = V * A

R = A / P

Definitions Qcapacity = flow capacity of channel (cfs)

Q = flow (cfs)

V = velocity (fps)

R = hydraulic radius (ft.2 / ft.)

Variables P = wetted perimeter

P = B + (2 * h)

h = height of water flow (ft)

h = A / B

A =

cross-sectional area of water flow (ft.

2)

A = B * h

Design Selection Constants S = hydraulic slope (%)

S = 1.000%

B = bottom channel width (ft)

B = 2.5

n = Manning's roughness coefficient

n = 0.0145



Calculations - Flow Range

Flow Condition Total Q (mgd)

Total Q (gpm)

Total Q (cfs)

Flow Depth (ft.)

Area (ft.

2)

Velocity (fps)

Facility Flow @ 20% WWTP Design Flow 0.300 208 0.46 0.092 0.23 2.02




WWTP Design Avg. Flow 1.500 1042 2.32 0.254 0.64 3.66

WWTP Flow - Peak Factor 1.5 2.250 1563 3.48 0.331 0.83 4.21



CONCLUSION: Since the flow velocities are greater than 2.0 fps, the design is acceptable.

A proposed concept is found in Appendix IV.



4.1.3 Influent Lift Station

4.1.3.1 Station Capacity

A new influent submersible lift station will be constructed adjacent to the existing lift station,

which will be abandoned. A lift station should be sized to serve the WWTP’s peak flows plus any

on-site returns which flow into the wetwell. Normally, a peaking factor (relative to the average

daily flow rate) of 2.5 is used. However, the presence of the existing overflow pond adjacent to the

proposed lift station allows this design to be less conservative than normal. Therefore, a peaking

factor of 2.0 (i.e., 1042 gpm x 2.0 = 2083 gpm) will be selected for the influent lift station.

Similarly, normal design would account for all potential on-site returns contributing at the same

time. These typical flows, expressed as a percentage of the WWTP average daily flow, include:

Filter backwash (2% - 5%)

Belt press operations (+/- 125 gpm, or 12%)

Supernatant drawoff, miscellaneous compartment drain, pond return, etc. (5%)

Total = 22% of ADF, or 230 gpm

Once again, the presence of the existing overflow pond adjacent to the proposed lift station

allows this design to be less conservative than normal. Therefore, a total on-site return flow rate of

8% ADF, or 83 gpm, will be selected. The selected return flow rate represents filter backwash flows

(5%) plus a reserve of 3% for all other purposes.



************************************************************************

Flow Contribution(s)

WWTP Qavg. Peak

Factor WWTP Qpeak

On-Site Return Flows * -- assumed (backwash,

basin drain, etc.) PS Design Flow -- (Qpeak + Qreturn)

(mgd) (gpm) --- (mgd) (gpm) (% of avg.) (gpm) (gpm)

1.500 1,042 2 3.000 2,083 8% 83 2,167

* On-Site Return Flows (typical):

Filter Backwash = 2% - 5% of through-put

Belt Press Backwash = +/- 125 gpm (while in operation); i.e., 12% of avg. WWTP flow

Reserve = Supernatant return, compartment drain, pond return, etc. (to be coordinated with available PS capacity) -- say, 5%

Total = 22%

NOTE: Flow contributions in excess of pumping capacity will overflow to the pond, and can be returned at low-flow times.

Selection: Because of pond overflow storage, provide additional capacity for only 8% (based on engineering judgment: 5% filter backwash + 3% reserve), instead of 22%, on-site return flow contribution.

************************************************************************

The influent lift station design capacity selection is 2,250 gpm, as rounded up from the above

chart. Calculations are based on these conversion factors:

24 hours per day

60 minutes per hour

1,000,000 gallons per million gallons

In the event that actual WWTP influent plus on-site return flows exceed the station’s pumping

capacity, the excess flow will spill directly into the overflow pond via an emergency relief pipe. See

Section 4.4.2 for a description of the overflow pond.



4.1.3.2 Force Main Termination

The pumps will discharge through either a common force main, or through separate force

mains. The proximity of the force main termination presents an opportunity to economically install

multiple force mains so that each pump operates independently without influencing the other

pumps. This decision will be reviewed in Section 4.1.3.4. However, whichever force main selection

is made, the termination point will be the influent splitter box that is described in Section 4.1.4.

4.1.3.3 Size Pumps

The influent lift station pumps will be selected so that the station capacity can be achieved with

the largest pump out of service. A secondary goal is to select pumping rates that can best supply

steady flows to the downstream treatment basins rather than creating flow surges. For example, a

10,000 gpm pump that operates for a few seconds then rests for several minutes creates massive

surges and is less preferable to a lower-flow pump that can operate for longer durations with fewer

start-stop cycles.

Two (2) options will be considered:

Option 1 – 2 peak daily flow (PDF) pumps, each rated at 2,250 gpm

Option 2 – 3 average daily flow (ADF) pumps, each rated at 1,125 gpm

Total pump run time will be analyzed for each proposed option. Each analysis verifies that the

station’s design capacity can be met assuming the largest pump is out of service.

Formulas

Total pump run time (min./day) = {(Actual facility flow, gpm) x (60 min/hr) x (24 hr/day)} /

{(Pump flow rate, gpm) x (# of pumps operating)}

Total pump run time (%/day) = (Total pump run time, min./day) / (1,440 min./day)



************************************************************************

Option 1 Flow Check (w/ largest pump out of service)

Pump1 Flow = 2,250 gpm

Pump2 Flow =

out of service gpm

Actual Facility Flow

(System Flow + On-Site Return Flow)

# of Pumps Required

Total Pump Run Time

Total Pump Run

Time

(gpm) (mgd) (each) (minutes) (% of day)

200 0.288 1 128 8.9%

300 0.432 1 192 13.3%

400 0.576 1 256 17.8%

500 0.720 1 320 22.2%

600 0.864 1 384 26.7%

700 1.008 1 448 31.1%

800 1.152 1 512 35.6%

900 1.296 1 576 40.0%

1000 1.440 1 640 44.4%

1100 1.584 1 704 48.9%

1200 1.728 1 768 53.3%

1300 1.872 1 832 57.8%

1400 2.016 1 896 62.2%

1500 2.160 1 960 66.7%

1600 2.304 1 1,024 71.1%

1700 2.448 1 1,088 75.6%

1800 2.592 1 1,152 80.0%

1900 2.736 1 1,216 84.4%

2000 2.880 1 1,280 88.9%

2100 3.024 1 1,344 93.3%

2200 3.168 1 1,408 97.8%

2250 3.240 1 1,440 100.0%

************************************************************************



************************************************************************

Option 2 Flow Check (w/ largest pump out of service)



Pump3 Flow =

out of service gpm

Actual Facility Flow

(System Flow + On-Site Return Flow)

# of Pumps Required

Total Pump Run Time

Total Pump Run

Time

(gpm) (mgd) (each) (minutes) (% of day)

200 0.288 1 256 17.8%

300 0.432 1 384 26.7%

400 0.576 1 512 35.6%

500 0.720 1 640 44.4%

600 0.864 1 768 53.3%

700 1.008 1 896 62.2%

800 1.152 1 1,024 71.1%

900 1.296 1 1,152 80.0%

1000 1.440 1 1,280 88.9%

1100 1.584 1 1,408 97.8%

1200 1.728 2 768 53.3%

1300 1.872 2 832 57.8%

1400 2.016 2 896 62.2%

1500 2.160 2 960 66.7%

1600 2.304 2 1,024 71.1%

1700 2.448 2 1,088 75.6%

1800 2.592 2 1,152 80.0%

1900 2.736 2 1,216 84.4%

2000 2.880 2 1,280 88.9%

2100 3.024 2 1,344 93.3%

2200 3.168 2 1,408 97.8%

2250 3.240 2 1,440 100.0%

************************************************************************

Because of the steadier flows under Option 2, the design pump arrangement selection will be

the triplex ADF pumps, as follows:

Pump 1 = 1,125 gpm

Pump 2 = 1,125 gpm

Pump 3 = 1,125 gpm



4.1.3.4 Force Main Selection

Three (3) separate force mains will be constructed so that each pump can operate

independently of the others during parallel pumping operations. Good engineering practice calls

for minimum velocities to be 2.0 feet per second to prevent solids deposition within the pipe, and

for maximum velocities to be 5.0 feet per second to reduce excessive horsepower required to

overcome friction losses.

Formulas

Q = V x A

- and –

V = Q /A

with,

Q = flow (cfs)

V = velocity (fps)

A = cross-sectional flow area (square feet)

Table 4-02

Influent Force Main Selecton Chart

Design Flow Rate (gpm) 1125

Force Main diameter (inches)

Velocity at Design Flow Rate (fps)

4 28.72

6 12.77

8 7.18

10 4.60

12 3.19

16 1.80

18 1.42

The design force main selection is three (3) 10-inch force mains.



4.1.3.5 Wetwell

Relationship to Overflow Pond

Since the wetwell will connect to the overflow pond via an emergency relief (i.e., static

overflow) pipe, the top of the proposed concrete wetwell will be set at the same elevation as the

overflow pond’s existing dam elevation in order to prevent accidental spillage. The normal

operating level of the wetwell will fluctuate between a “Pumps Off” elevation and a “High Level

Alarm” elevation. If the flow into the lift station exceeds the station’s pumping capacity, or if the

pumps fail to operate, or if some other scenario causes the liquid level to rise, water will flow

through the emergency relief pipe from the wetwell to the overflow pond. The emergency relief

pipe invert elevation will be set above the “High Level Alarm” elevation so that water will enter the

overflow pond above its full pool water level.

At the operator’s discretion, he can open a valve at the Pond Withdrawal Station in order to

draw water out of the overflow pond back into the influent lift station via a pond drain pipe.

Under certain circumstances the operator will need to bypass one treatment train or the other.

Although the influent splitter box will allow all flow to be diverted to the in-service treatment train,

the influent pumping rate cannot be reduced so it may overload the treatment basins and clarifier.

The operator may need to make provisions to maintain a safe total flow into the train. These

provisions could involve the following strategies:

Short-term storage of all flow in the overflow pond

operating the lift station in “hand” mode

adjusting pump control set points

placing backup pumps in “off” mode

etc.

Storage Volume

Wetwell storage is based on the following calculation.

Wetwell Volumerequired = (t x Q) / 2

with,

t = cycle time (time between successive pump starts)

Allowable pump starts per hour = 10

t = (60 minutes/hour) / (10 pump starts/hour)

= 6 minutes / pump start

Q = 1125 gpm



Substituting,

Wetwell Volumerequired = (6 x 1125) / 2

= 3,375 gallons

= 451.20 ft.3

The wetwell will be sized to provide the required volume, as shown in the calculations below.

Select Wetwell Dimensions

Wetwell Diameter 12 Feet

Wetwell Radius 6 Feet

Formulas

Volume = π * (R2) * Height

Height = (Volume) / [π * (R2)]

Wetwell Height required

Height (feet) = 3.99

Wetwell Design Height

Design Height (feet) = 4.00

Abandon Existing Wetwell

The existing lift station and wetwell will be abandoned from service. If it is in conflict with other

construction, it will be demolished and removed. Otherwise, all equipment will be removed and

disposed of, the structure will be cut off approximately 3 feet below ground, the bottom will be

cored to allow groundwater to equalize inside and outside the structure, the interior will be filled

with gravel, and the structure will be abandoned in place.

4.1.3.6 System Hydraulics

During final design the system hydraulic calculations will be performed based on actual force

main alignment, influent lift station elevations, and influent splitter box elevations. However,

preliminary system hydraulic calculations are presented below to aid in the horsepower selection

for potential pumps.



Headloss Formula

HL per 100' = { 0.2083 x [(100/C)^1.852

] x (Q^1.852

) } / [dia^4.87

]

= friction loss, ft. of H2O per 100 ft.

with, C = Hazen-Williams Friction Coefficient

C = 140 for new pipe; 120 for design pipe; 100 for old pipe

Q = Flow in pipe segment (gpm)

dia. = pipe diameter (inches)

Nominal Pump Capacities Triplex PS with each pump at same capacity

Pump 1 1125 gpm

Pump 2 1125 gpm

Pump 3 1125 gpm

Critical Point

The critical point is at the force main termination point (influent splitter box).

Equivalent Pipe Diameter

Selection FM Dia. (In.)

See influent force main selection chart 10

Calculate Force Main Equivalent Pipe Length Typical Headloss Values

Fitting

Pipe Diameter (Inches)

4 6 8 10

Equivalent Pipe Length (LF)

90-deg. Bend 11 16 21 26

45-deg. Bend 5 8 10 13

Plug Valve 3 4 5 6

Check Valve 27 40 53 67

Tee 22 33 43 56



Force Main Run

Equiv. Diameter (inches): 10

Qty. Description Equiv. Length

per item Total (ft.)

20 Riser Pipe 1 20

200 STA. 0+00 to STA. ??? 1 200

8" x 10" increaser (estimated) 13 0

2 90* bend (vertical) 26 52

1 90* bend (horizontal) 26 26

4 45* bend 13 52

1 Plug valve 6 6

1 Check valve 67 67

1 Tee/Cross 56 56

Total 479

Total Equivalent FM Pipe Length Summary

Equiv. Diameter (inches): 10

Category

Assumed Length (LF) Comment

Force Main Length (ft.) 220 estimated

Estimated Equivalent Length of Fittings (ft.) 259

See force main run calculations

Total Equivalent FM Length 479

Use Equivalent FM Length in Calculations 500

Calculate Static Head NOTE: Since the force main high point is at the end of the alignment, this is the critical point.

NOTE: Minimum static head is based on "Pump On" water elevation and Influent Splitter Box I.E. NOTE: Max. static head is based on "Pump Off" water elev. and max. water level at influent splitter box

Calculation Point

Minimum Head Conditions (Ft.)

Maximum Head Conditions (Ft.)

Elevation at critical point

188.00

189.00

Influent LS ("Pump On" or "Pump Off")

156.00

152.00

Static Head (Ft.)

32.00

37.00



Calculate System Curve

Common Factors for all Alternatives

Minimum Static Head (ft.): 32.00

Maximum Static Head (ft.): 37.00

Pipe Diameter (in.): 10

Equivalent Pipe Length (ft.): 500

Pump Station Head losses (ft.)::

Included in force main run

calculations



Alternative No. 1 (C = 140)

C 140

Q HL / 100' (ft. / 100

ft.) HL (ft.) TDHmin (ft.)

TDHmax (ft.)

0 0.00 0.00 32.00

37.00

200 0.03 0.14 32.14

37.14

400 0.10 0.50 32.50

37.50

600 0.21 1.05 33.05

38.05

800 0.36 1.79 33.79

38.79

1000 0.54 2.71 34.71

39.71

1100 0.65 3.23 35.23

40.23

1125 0.67 3.37 35.37

40.37

1150 0.70 3.51 35.51

40.51

1200 0.76 3.80 35.80

40.80

1400 1.01 5.05 37.05

42.05

1600 1.29 6.47 38.47

43.47

1800 1.61 8.05 40.05

45.05

2000 1.96 9.78 41.78

46.78

2200 2.33 11.67 43.67

48.67

Alternative No. 2, Design Condition (C = 120)

C 120

Q HL / 100' (ft. / 100


TDHmax (ft.)

0 0.00 0.00 32.00

37.00

200 0.04 0.18 32.18

37.18

400 0.13 0.66 32.66

37.66

600 0.28 1.40 33.40

38.40

800 0.48 2.39 34.39

39.39

1000 0.72 3.61 35.61

40.61

1100 0.86 4.30 36.30

41.30

1125 0.90 4.48 36.48

41.48

1150 0.93 4.67 36.67

41.67

1200 1.01 5.05 37.05

42.05

1400 1.34 6.72 38.72

43.72

1600 1.72 8.61 40.61

45.61

1800 2.14 10.71 42.71

47.71

2000 2.60 13.02 45.02

50.02

2200 3.11 15.53 47.53

52.53



Alternative No. 3 (C = 100)

C 100

Q HL / 100' (ft. / 100


TDHmax (ft.)

0 0.00 0.00 32.00

37.00

200 0.05 0.26 32.26

37.26

400 0.19 0.93 32.93

37.93

600 0.39 1.96 33.96

38.96

800 0.67 3.34 35.34

40.34

1000 1.01 5.05 37.05

42.05

1100 1.21 6.03 38.03

43.03

1125 1.26 6.29 38.29

43.29

1150 1.31 6.55 38.55

43.55

1200 1.42 7.08 39.08

44.08

1400 1.89 9.43 41.43

46.43

1600 2.41 12.07 44.07

49.07

1800 3.00 15.01 47.01

52.01

2000 3.65 18.25 50.25

55.25

2200 4.35 21.77 53.77

58.77

Specify Pump Conditions

Flow (GPM) Condition Design C

Factor TDHmin (ft.)

TDHmax (ft.)

1125 Pumps 1, 2, & 3 Design Condition 120 36.48

41.48

Calculate Brake Horsepower

BHP = {GPM x TDH} / {3960 x Pump Eff. x Motor Eff.}

Pump Efficiency = 35% (assumed)

Motor Efficiency = 92% (assumed)

Flow (GPM) Condition

BHPmin (Hp)

BHPmax (Hp)

1125 Pumps 1, 2, & 3 Design Condition

32.2

36.6

Control Panel Electrical Design Parameters

Pump Slot HP Rating

Pump No. 1 50

Pump No. 2 50

Pump No. 3 50



4.1.3.7 Pump Selection

During final design pumps will be selected based on the system hydraulics. A preliminary Pump

Curve vs. System Head Curve is shown on the following page:



4.1.4 Influent Splitter Box An influent splitter box will be designed to split the flow to the two (2) treatment trains. Once

split the flow, including internal RAS recycle flow, will remain split between the biological treatment

system and the secondary clarifiers before coming together again. The flow split ratio, as

calculated for design flow, will be 1.100 : 0.400, or 73.33% to Train 1 and 26.67% to Train 2. The

flow split ratio for other flow rates may be slightly different due to the non-linear nature of the weir

formulas. In particular, the flow split ratio will be analyzed for the following flow rates:

1,042 gpm (WWTP design capacity = 1.5 mgd)

1,125 gpm (one influent pump operating)

2,250 gpm (two influent pumps operating)

3,375 gpm (three influent pumps operating)

3,675 gpm (3 pumps x 1225 gpm, per Section 4.1.3.7 pump curve maximum throughput)

The influent splitter box will be a concrete structure. The influent force mains will terminate at

the upper deck, which has two (2) separate rectangular contracted weir openings to direct flow to

one train or the other, or to both. Furthermore, each opening can be temporarily shut off to isolate

a treatment tank by raising a weir gate high enough to prevent flow from passing through. (These

weir gates could be adjusted to allow the operator to create any theoretical flow split desired.)

Forward flow will pass through the weir openings and fall to the distribution deck, which is

connected via pipes to the respective anaerobic basins.

Calculations are based on the formulas and characteristics shown below.

Weir Formula Use Cipoletti Weir (Cipoletti Formula)

Q = 3.367 * B * h^(3/2)

(Reference page 211 of "Hydraulics Handbook")

with, Q = volume of flow (cfs)

h = head on crest (feet)

B = length of crest (feet), sometimes referenced as "L"

Flow Formula Q = V * A

with, V = velocity (fps)

A = area (square feet)



Weir Design Elements

Weir Opening Characteristics Design Selection Type of Weir Cipoletti Design Overflow Weir #1

Length, B (Ft.) 2.75 Design Overflow Weir #2

Length, B (Ft.) 1.00

Flow Split Ratio Calculations

Outlet

Target Flow Target Flow Split

Share

mgd %

to Train 1 1.100 73.33%

to Train 2 0.400 26.67%

Total 1.500 100.00%

Flows are calculated for various water depths, as shown on the next page. The proposed weir

splits the flow at the desired ratio of 73.33% / 26.67% across the expected facility flow rates. Finally,

various scenarios were analyzed that simulated one or the other weir being out of service to check

for the overall maximum potential water surface at the weir openings. Peak influent pumping rates

result in an 8.99-inch water depth when both weirs are in service, but they result in 21.7-inch water

depth when only the smaller weir is in service.



Table 4-03

Influent Splitter Box Weir Flow Split Chart

head (ft.)

head (in.)

To Train 1 To Train 2 Total Flow

B (ft.) Q (cfs) Q (gpm) Q

(mgd)

Flow Share

(%) B (ft.) Q (cfs) Q (gpm) Q (mgd)

Flow Share

(%) Q (gpm) Q (mgd)

All weir gates open 0.0000 0.00 2.75 0.000 0.0 0.000 --- 1.00 0.000 0.0 0.000 --- 0.0 0.000

0.1000 1.20 2.75 0.293 131.4 0.189 73.33% 1.00 0.106 47.8 0.069 26.67% 179.2 0.258

0.2000 2.40 2.75 0.828 371.7 0.535 73.33% 1.00 0.301 135.2 0.195 26.67% 506.8 0.730

0.3000 3.60 2.75 1.521 682.8 0.983 73.33% 1.00 0.553 248.3 0.358 26.67% 931.1 1.341

0.3233 3.88 2.75 1.702 763.9 1.100 73.33% 1.00 0.619 277.8 0.400 26.67% 1041.7 1.500

0.3403 4.08 2.75 1.838 824.9 1.188 73.33% 1.00 0.668 300.0 0.432 26.67% 1124.9 1.620

0.4000 4.80 2.75 2.342 1051.3 1.514 73.33% 1.00 0.852 382.3 0.550 26.67% 1433.6 2.064

0.5000 6.00 2.75 3.274 1469.2 2.116 73.33% 1.00 1.190 534.3 0.769 26.67% 2003.5 2.885

0.5402 6.48 2.75 3.676 1649.9 2.376 73.33% 1.00 1.337 600.0 0.864 26.67% 2249.9 3.240

0.6000 7.20 2.75 4.303 1931.3 2.781 73.33% 1.00 1.565 702.3 1.011 26.67% 2633.6 3.792

0.7000 8.40 2.75 5.423 2433.7 3.505 73.33% 1.00 1.972 885.0 1.274 26.67% 3318.7 4.779

0.7079 8.49 2.75 5.515 2475.1 3.564 73.33% 1.00 2.005 900.0 1.296 26.67% 3375.1 4.860

0.7493 8.99 2.75 6.006 2695.3 3.881 73.33% 1.00 2.184 980.1 1.411 26.67% 3675.5 5.293

Train 1 weir gate open; Train 2 weir gate closed 0.3976 4.77 2.75 2.321 1041.8 1.500 100.00% --- --- --- --- --- 1041.8 1.500

0.4185 5.02 2.75 2.507 1125.1 1.620 100.00% --- --- --- --- --- 1125.1 1.620

0.6644 7.97 2.75 5.014 2250.5 3.241 100.00% --- --- --- --- --- 2250.5 3.241

0.8705 10.45 2.75 7.520 3375.1 4.860 100.00% --- --- --- --- --- 3375.1 4.860

0.9213 11.06 2.75 8.188 3674.8 5.292 100.00% --- --- --- --- --- 3674.8 5.292

Train 1 weir gate closed; Train 2 weir gate open 0.7805 9.37 --- --- --- --- --- 1.00 2.322 1042.0 1.500 100.00% 1042.0 1.500

0.8215 9.86 --- --- --- --- --- 1.00 2.507 1125.1 1.620 100.00% 1125.1 1.620

1.2943 15.53 --- --- --- --- --- 1.00 4.958 2225.1 3.204 100.00% 2225.1 3.204

1.7086 20.50 --- --- --- --- --- 1.00 7.520 3374.9 4.860 100.00% 3374.9 4.860

1.8085 21.70 --- --- --- --- --- 1.00 8.189 3675.1 5.292 100.00% 3675.1 5.292



4.1.5 Biological Treatment System The selected process for the combined biological nutrient removal of nitrogen and phosphorous

is the 5-Stage Bardenpho Process (Anaerobic + Pre-Anoxic + Aerobic + Post-Anoxic + Re-Aeration)

described in “Wastewater Engineering – Treatment, Disposal, and Reuse” (Fourth Edition) by

Metcalf and Eddy, Inc., which is referenced as Exhibit No. 3. In particular, see the following

chapters for detailed descriptions:

Chapter 8-5 – “Processes for Biological Nitrogen Removal”

Chapter 8-6 – “Processes for Biological Phosphorus Removal”

The 5-Stage Bardenpho Process and subsequent secondary clarification typically achieve

treatment limits as shown below:

Total nitrogen concentration of 3.0 mg/l

Total phosphorus concentration of 2.0 mg/l

The facility flow is split between the two treatment trains, but not 50%/50%. Train 1 treats 1.1

mgd through a new tank, and Train 2 treats 0.4 mgd through the re-configured existing tank. The

following sub-sections provide greater detail on the design processes.

A proposed concept is found in Appendix V.

4.1.5.1 Potential Process Equipment Manufacturers

Different manufacturers can accommodate a 5-Stage Bardenpho Process. Some manufacturers

utilize surface aerators and sub-surface mixers within the different basins, while circulating water

around an oxidation ditch in the aeration basin which takes advantage of the water’s momentum for

internal recycles via gate openings. Other manufacturers utilize diffused air for oxygen transfer and

mixing within a simpler overall structure, while using recycle pumps to move water between certain

basins.

The selected design will use the “package” plant concept consisting of air diffusers installed on

the basin floor. Each compartment will be located within a larger circular tank with internal divider

walls. Two (2) potential “package” plant manufacturers include EVOQUA (formerly known as

DAVCO -- Thomasville, Georgia) and Smith & Loveless (Lenexa, Kansas).

4.1.5.2 Process Description

Table 4-04 shows the typical design ranges for various parameters. This information is primarily

taken from Tables 8-22 & 8-26 of Exhibit No. 3. Actual ranges for the DAVCO or S&L process may

vary slightly, as shown in the calculations found in later sections.



Table 4-04

Typical Design Ranges for 5-Stage Bardenpho Process

Design Parameter Unit

5-Stage Bardenpho

Process Reference

Food-to-microorganism Ratio (F/M)

lb. BOD / lb. MLVSS per day 0.1 - 0.2 See Note 1

Solids Retention Time, Ɵc days 10 - 20 See Note 2

MLSS mg/l 3,000 - 4,000 See Note 2

Hydraulic Retention Time, Ɵ

hour

8 - 22 Sum of Ranges

Anaerobic Zone 0.5 - 1.5 See Note 2

Pre-Anoxic Zone 1 - 3 See Note 2

Aerobic Zone 4 - 12 See Note 2

Post-Anoxic Zone 2 - 4 See Note 2

Re-Aeration Zone 0.5 - 1 See Note 2

Return Activated Sludge % of Influent 50 - 100 See Note 2

Internal Recycle % of Influent 200 - 400 See Note 2

NOTE 1: Parameters are summarized from Table 11-27 of "Wastewater Engineering Treatment and Reuse" (Third Edition) by Metcalf & Eddy

NOTE 2: Parameters are summarized from Tables 8-22 & 8-26 of "Wastewater Engineering Treatment and Reuse" (Fourth Edition) by Metcalf & Eddy

There are 6 basic biological steps to the 5-Stage Bardenpho Process, which includes the

clarification stage that is described further in a later chapter. Each step is described below. Please

see Figure 4-03 for a process schematic.

1. Anaerobic contacting - WWTP influent and RAS are contacted in the anaerobic selector in the absence of molecular or chemically available oxygen. Microorganisms feed on soluble BOD which produces volatile fatty acids (VFAs). The biomass absorbs the VFAs and converts them to a polyphosphate, which is an internally–stored energy source. This process releases dissolved phosphorous into the mixed liquor.

2. Pre-Anoxic denitrification – The dissolved oxygen levels are at zero in the anoxic zone. However, chemically bound oxygen in the nitrates stream into the anoxic zone with the flow of recycled, nitrified mixed liquor from the aerobic (oxidation) zone. The biomass utilizes cellular oxygen from the nitrates to oxidize BOD. Denitrification occurs as the nitrates are reduced to nitrogen gas, which is released to the atmosphere.

3. Aerobic oxidation and nitrification – BOD and ammonia are biologically oxidized to CO2, nitrate, and water in the oxygen–rich aerobic (oxidation) zone. The microorganisms, which utilize the internally-stored polyphosphates as an energy source, seek the dissolved phosphorous. This process reduces dissolved phosphorous levels to near zero.



4. Post-Anoxic Zone – Nitrate is reduced in the absence of oxygen to nitrogen gas through endogenous respiration to produce a low effluent nitrate concentration. There will be negligible amounts of oxygen and BOD available in this reactor.

5. Re-Aeration Zone – The activated sludge receives oxygen in the final step to prevent anaerobic conditions and the secondary release of phosphorous. When maintained in an aerobic environment, the Bardenpho system mixed liquor contains 5% to 6% phosphorous. If the sludge is permitted to become septic, phosphorous could be released in the final clarifier. The introduction of air ensures that the mixed liquor remains aerobic and retains the phosphorous.

6. Clarification, sludge wasting, and phosphorous removal – The phosphorous-heavy microorganisms settle in the secondary clarifiers. As the biomass is wasted and removed from the WWTP, the cellular load of phosphorous is removed from the flow stream.

4.1.5.3 Calculations

Design calculations have been developed based on the process theory found in “Wastewater

Engineering – Treatment, Disposal, and Reuse” (Fourth Edition) by Metcalf and Eddy, Inc. These

calculations are found in Appendix VI. These design calculations are in general agreement with the

manufacturer calculations found in Appendix V.

The design is summarized in the following table.



Table 4-05

Biological Nutrient Removal Treatment Design Summary

Lyons WWTP (1.1 mgd Train)


Category Characteristic Symbol Unit Value Value Row (A)

Design Capacity Flow Rate Q gpm 1.100 0.400 1

Wastewater Influent Characteristics

Total 5-day biological oxygen

demand BOD5 mg / l 350 350 4

Total Suspended Solids TSS mg / l 350 350 5

Ammonia - Nitrogen NH3-N mg / l 30 30 6

Total Kjeldahl Nitrogen (Organic N + Ammonia N) TKN mg / l 45 45 7

Total Phosphorus TP mg / l 10 10 9

Alkalinity (as CaCO3) Alk as CaCO3 mg / l 140 140 10

Design Factors

Solids Retention Time SRTselection days 11.6 11.6 61

Mixed Liquor Suspended Solids MLSS mg / l 3500 3500 127

RAS recycle ratio (RAS flowrate /

influent flowrate) R % Q 50.0% 50.0% 164

Internal recycle ratio (internal

recycle flowrate / influent flowrate) IR --- 3.3 3.3 165

Design Selections -- Anaerobic Basin(s)

Volume Selection Vanaerobic

(selection) Gal 143,964 52,302 286

Number of Anaerobic Basins #anaerobic basins each 3 3 289

Volume per Anaerobic Basin

Vper anaerobic

basin Gal 47,988 17,434 293

Hydraulic Retention Time τ hours 3.14 3.14 287






Design Selections -- Anoxic Basin(s)

Volume Selection Vnox (selection) Gal 182,266 66,038 177

Number of Anoxic Basins #anoxic basins each 2 2 180

Volume per Anoxic Basin Vper anoxic basin Gal 91,133 33,019 184


Anoxic Power (selection)

Poweranoxic

(selection) kW 7 2.5 257

Design Selections -- Aeration Basin(s)

Volume Selection Vselection Gal 1,046,049 379,853 132

Number of Aeration Basins #aeration basins each 1 1 133

Volume per Aeration Basin Vper aeration basin Gal 1,046,049 379,853 137


Design Selections -- Post Anoxic Basin(s)

Volume Selection V2nd nox (selection) Gal 319,098 115,963 300

Number of Anoxic Basins #2nd anoxic basins each 1 1 303

Volume per Anoxic Basin

Vper 2nd anoxic

basin Gal 319,098 115,963 307


Design Selections -- Re-Aeration Basin(s)

Volume Selection VRe-Aeration

(selection) Gal 35,925 13,208 314

Number of Re-Aeration Basins #Re-Aeration basins each 1 1 317

Volume per Re-Aeration Basin

Vper Re-Aeration

basin Gal 35,925 13,208 321







Effluent Requirements

(B)


demand BOD5 mg / l 5 5 34


Ammonia - Nitrogen NH3-N mg / l 1 1 36

Total Nitrogen TN mg / l 3 3 37

Total Phosphorus TP mg / l 1 1 38

Estimated BNR Treatment Tanks

Effluent Concentrations

(C)


demand BOD5 mg / l 9.0 9.0 325


Ammonia - Nitrogen NH3-N mg / l 1.0 1.0 99

Total Nitrogen TN mg / l 3.0 3.0 326

Total Phosphorus TP mg / l 0.3 0.3 280

Alkalinity Added

Alkalinity to be added (to maintain

neutral pH) Alkadded (as

CaCO3) mg / l 64.05 64.05 251

Mass of alkalinity to be added (to maintain neutral

pH) Alkmass # / d 588 214 253

NOTE A: Row number refers to row number found in Treatment Design Calculations

NOTE B: Effluent requirements are based upon project Wasteload Allocation limits, or upon project NPDES Permit limits. NOTE C: Effluent concentration is estimated at the outlet pipe of the BNR treatment system. Other downstream components

will treat the effluent further.



4.1.5.4 Treatment Train Summary

The treatment flow will be segregated through Train 1 (1.1 mgd) and Train 2 (0.4 mgd).

However, it will be advantageous to make provisions for interconnections.

Bypass piping with isolation valves will be installed to connect Train 1’s Re-Aeration Zone to

Train 2’s Secondary Clarifier, and vice-versa. Normally, these bypass valves will be closed to fully

segregate flow within each train. However, if one or the other secondary clarifiers has to be taken

off-line for maintenance, then the opposite one could temporarily handle all flow.

Similarly, provisions can be made to return the RAS to the opposite Anaerobic Basin. In fact, the

WAS line described in Section 4.3.1.2 can be valved to return activated sludge to the opposite

Anaerobic Basin instead of to the digester splitter box.

4.1.6 Secondary Clarifiers It is proposed to construct two (2) secondary clarifiers, one dedicated to each treatment train.

Each clarifier will sized for 100% of the respective treatment train’s flow. In the event that one unit

is out of service, the remaining unit would be overloaded under peak flow conditions. Alternatively,

the operator can divert influent into the overflow pond when a clarifier is out of service.

Maintenance of the clarifiers will include periodic inspections and weekly washdown of the

clarifier weirs and trough. It may be necessary to change out the drive system in the future. In

advance of this procedure, the operator will need to order a spare system. Changing the drive

system would then take 1 to 2 days to complete.

4.1.6.1 Secondary Clarifier Design Criteria

Design standards for the secondary clarifiers are taken from the Chapter 70 of the 2004 edition

of the “Recommended Standards for Wastewater Facilities”, commonly referred to as the “Ten

States Standards” which is referenced as Exhibit No. 5. See Table 4-06 for a summary of the design

criteria. Paragraph 72.43 requires the weir loading rtes to be based on the pump delivery rates (as

supplied by the influent lift station), not merely the hypothetical facility peak rate, in order to

prevent short-circuiting.

Table 4-06

Secondary Clarifier Design Criteria

Design Parameter Units Criteria

Minimum Side Water Depth feet 12

Peak Surface Overflow Rate for Nitrification GPD / ft.2 1,000

Peak Surface Overflow Rate for Phosphorous with Chemical Addition GPD / ft.

2 900

Peak Loading Rate (for WWTPs greater than 1 mgd) GPD / lin. ft. 30,000

Peak Solids Loading Rate # / day / ft.2 35



Since the flows to each treatment train are split at the influent splitter box, the design loadings

and flow rates for each secondary clarifier will be in proportion to the flow split, as follows:

Table 4-07

Secondary Clarifier Design Loadings

Parameter Units Total WWTP

Flow Clarifier 1 Flow Clarifier 2 Flow

Share of Facility Flow % 100.00% 73.33% 26.67%

Average WWTP Flow, Q mgd 1.500 1.100 0.400

Average WWTP Flow Rate, Q gpm 1042 764 278

Peak (2.0 peak factor) WWTP Flow Rate, QWWTP Peak gpm 2083 1528 556

Peak (2 - 1,125 gpm influent pumps) WWTP Flow Rate, QNormal Pump Peak gpm 2250 1650 600

Peak (3 - 1,125 gpm influent pumps) WWTP Flow Rate, QMax Pump Peak gpm 3375 2475 900

Return Activated Sludge Flow Rate, maximum, QRAS % of Influent 100% 100% 100%

Return Activated Sludge Flow Rate, maximum, QRAS gpm 1042 764 278

Max. Hydraulic Throughput (QMax Pump

Peak + QRAS) gpm 4417 3239 1178

Total Suspended Solids mg/l 350 350 350

MLSS mg/l 4000 4000 4000


See the clarifier sizing calculations below. The manufacturer’s supporting process calculations

dated March 24, 2016 are included in Appendix V.

Formulas -- Diameter Calculated by Peak Surface Overflow Rate

Areamin = (Peak Flow) / (Peak Surface Overflow Ratemin)

with, Peak Flow (mgd) = (Peak Flow Rate, gpm) x (60 min./hr.) x (24 hr./day) x (1 mgal / 1,000,000 gal)

Peak Flow (gpd) = (Peak Flow, mgd) x (1,000,000 gal / 1 mgal)

Peak Flow Rate (gpm) = from Section 4.1.6.1

Peak Surface Overflow Rate = from Section 4.1.6.1

Area = π * (R2)

Radiusmin = (Areamin / π)1/2

Diametermin = 2 x Radiusmin



Formulas -- Diameter Calculated by Peak Loading Rate

Overflow Weir Length (ft.) = (Peak Flow) / (Peak Loading Rate)

with, Peak Flow (mgd) = same as above

Peak Flow (gpd) = same as above


Peak Loading Rate = from Section 4.1.6.1

Overflow Weir Lengthmin (ft.) = 2 x π x Rmin

Radiusmin = (Overflow Weir Lengthmin) / (2 x π)

Diametermin = same as above

Formulas -- Diameter Calculated by Peak Solids Loading Rate

Total Surface Area (ft.2) = (Peak Solids Loading) / (Peak Solids Loading Rate)

with, Peak Flow (mgd) = same as above

Peak Flow (gpd) = same as above

Peak Solids Loading (ppd) = {(Peak flow rate, gpm) x (TSS concentration, mg/l) x 0.012}

+ {(Max. RAS rate, gpm) x (MLSS concentration, mg/l) x 0.012}

Peak Solids Loading Rate = from Section 4.1.6.1


TSS = from Section 4.1.6.1

Max. RAS rate = from Section 4.1.6.1

Conversion Factor, 0.012 = convert from gpm & mg/l to ppd

= (1 kg / 1,000,000 mg)

x (2.205 # / 1 kg)

x (3.7854 L / gal)

x (60 min. / hr.)

x (24 hr. / day)

Area = π * (R2)

Radiusmin = (Areamin / π)1/2

Diametermin = 2 x Radiusmin



Table 4-08

Secondary Clarifier Calculations

Parameter Units Clarifier 1 Clarifier 2

Diameter (calculated by Peak Surface Overflow Rate)

Peak (2.0 peak factor) WWTP Flow Rate, QWWTP Peak gpm 1528 556

Peak Flow mgd 2.200 0.800

Peak Flow gpd 2,200,000 800,000

Peak Surface Overflow Rate for Phosphorous with Chemical Addition GPD / ft.

2 900 900

Areamin ft.2 2,444 889

Radiusmin ft. 27.9 16.8

Diametermin ft. 55.8 33.6

Diameter (calculated by Peak Loading Rate)

Peak (3 - 1,125 gpm influent pumps) WWTP Flow Rate, QMax Pump Peak gpm 2475 900


Peak Flow gpd 3,564,000 1,296,000

Peak Loading Rate GPD / lin. ft. 30,000 30,000

Overflow Weir Length ft. 118.8 43.2



Diameter (calculated by Peak Solids Loading Rate)



Peak Flow gpd 2,200,000 800,000

Conversion Factor gpm & mg/l to

ppd 0.012 0.012

Total Suspended Solids mg/l 350 350

Peak Solids Loading, contribution from influent ppd 6,427 2,337

Return Activated Sludge Flow Rate, maximum, QRAS gpm 764 278

MLSS mg/l 4000 4000

Peak Solids Loading, contribution from RAS ppd 36,726 13,355

Peak Solids Loading ppd 43,153 15,692

Peak Solids Loading Rate # / day / ft.2 35 35

Total Surface Area ft.2 1,233 448





4.1.6.3 Design Selection

Secondary clarifier 2 will be re-constructed in the center of the original treatment tank. The

existing diameter of 45 feet will be selected, while the depth is limited to the existing tank wall

heights.

Secondary clarifier 1 will be new construction located in the center of treatment tank no. 1. A

diameter of 62 feet, which exceeds the minimum requirements determined in the previous section,

is selected. The new walls can be constructed deeper than the existing adjacent tank no. 2;

however, the overflow weirs of the two clarifiers will be set at the elevations.

Table 4-09

Secondary Clarifier Design Selection


Design Selection Diameter ft. 62 45

Clarifier Surface Area ft.2 3,019 1,590

Overflow Weir Length ft. 194.8 141.4

Clarifier Depth (see EVOQUA 3/17/16 calcs.) ft. 16 13

Clarifier Volume (see EVOQUA 3/17/16 calcs.) gallons 362,170 362,170



4.1.6.4 Performance Verification

The same secondary clarifier design criteria from the earlier section will be analyzed for the

proposed design configuration.

Table 4-10

Secondary Clarifier Performance Verification


Design Criteria Checks (at WWTP 2.0 Peak Flow Rate)



Peak Flow gpd 2,200,000 800,000

Peak Surface Overflow Rate GPD / ft.2 729 503


Peak Solids Loading Rate # / day / ft.2 14.3 9.9

Design Criteria Checks (at Duplex Influent LS Peak Flow Rate)

Peak (2 - 1,125 gpm influent pumps) WWTP Flow Rate, QNormal Pump Peak gpm 1650 600


Peak Flow gpd 2,376,000 864,000

Peak Surface Overflow Rate GPD / ft.2 787 543



Design Criteria Checks (at Triplex Influent LS Peak Flow Rate)

Peak (3 - 1,125 gpm influent pumps) WWTP Flow Rate, QMax Pump Peak gpm 2475 900


Peak Flow gpd 3,564,000 1,296,000

Peak Surface Overflow Rate GPD / ft.2 1,180 815



The influent lift station is designed to meet capacity with two pumps operating, and the third

pump is present as a backup instead of for normal operations. Therefore, the normal facility peak

flows are generated by two pumps. This scenario meets all clarifier design criteria. Based on

paragraph 72.232 of the “Ten States Standards” the operating performance of the secondary

clarifiers will produce an effluent with the following characteristics:

TSS = 20 mg/l

Phosphorous = 1.0 mg/l



4.1.7 Surface Filtration

4.1.7.1 Description

Surface filtration process theory is described in Chapter 11-5 of “Wastewater Engineering –

Treatment, Disposal, and Reuse” (Fourth Edition) by Metcalf and Eddy, Inc. Secondary clarifier

effluent from the two separate treatment trains will blend together at the filter structure inlet

channel. As flow passes through the filter, a portion of the residual suspended solids will be

removed. A cloth media filter fabric has openings (i.e., 10 microns) to allow effluent to pass through

while solids are captured. As the filter collects solids, the fabric is backwashed and the solids can

return to the waste stream at the head of the plant. The solids are vacuumed off the filter surface

during the backwash sequence. Over time, some solids cannot be removed via the normal

backwash sequence, so a high-pressure backwash is necessary to restore the filtration capacity.

Clean filter effluent is used in the high pressure backwash procedure.

Cloth media has a finite life and must be replaced approximately every 3 – 7 years, depending

upon plant loads.

4.1.7.2 Design Loadings

Design influent and effluent loadings at the filter are shown in the table below. To be

conservative, influent loadings used in the filter calculations may be higher than the predicted

secondary clarifier effluent.

Table 4-11

Filter Design Loadings

Characteristic Unit Influent Loading from Secondary Clarifier

(1) Effluent Loading

Average TSS mg / l 20 5

Maximum TSS mg / l 30 ---

Phosphorus mg / l 1 to 2 ≤ 1

NOTE 1: Design influent loadings may be higher than effluent from upstream components (to be conservative).

4.1.7.3 Potential Equipment Manufacturers

The wastewater market offers two types of micro-screens. One type (i.e., Kruger) typically

consists of a membrane filter and flows from inside –to- outside. The other type (i.e., Aqua)

typically consists of a cloth media and flows from outside –to- inside. The second type will be

selected because of the designer’s preference to keep “dirty” water (such as heavy solids, grass

clippings, site debris, algae, etc.) on the outside of the filter rather than on the inside.

Two potential manufacturers are Aqua-Aerobics and Alfa-Laval.



4.1.7.4 Typical Parameters

Typical cloth media filter equipment information is presented below.

Table 4-12

Typical Cloth Media Disk Filter Design Parameters (1)

Item Unit Typical Value

Nominal pore size μm 10

Hydraulic loading rate m

3 / m

2 * min 0.1 - 0.27

gpm / ft2 24.5 - 66.25

Headloss through screen mm 50 - 300

inches 2 - 12

Disk submergence % height 100

% area 100

Disk diameter m 0.90 - 1.80

ft 3 - 6

Disk speed rpm 1) stationary during operation;

2) 1 rpm during backwash

Backwash and sludge wasting requirements % throughput

4.5 (at min. hydraulic loading) - 7.2 (at max. hydraulic

loading)

General NOTE: M&E refers to "Wastewater Engineering Treatment and Reuse" (Fourth Edition) by Metcalf & Eddy

NOTE 1: Information is from M&E Table 11-15 (values are converted from metric to English)


Table 4-13

Filter Design Calculations

Item Unit Value Row # Calculation

Design Conditions

Average Design Flow gpm 1,042 a ---

mgd 1.5 b ---

Peak Design Flow (1)

gpm 2,083 c ---

mgd 3.0 d ---

Hydraulic Maximum Flow (1) (2)

gpm 3,675 e ---

mgd 5.292 f ---

Average TSS mg / l 20 g ---

Maximum TSS mg / l 30 h ---

Equipment Design Criteria

Average Hydraulic Loading gpm / ft

2 (at avg.

flow) 3.25 i ---

Maximum Hydraulic Loading gpm / ft

2 (at max.

flow) 6.5 j ---

Allowable Solids Loading # TSS / (ft2 * day) 3.25 k ---



Item Unit Value Row # Calculation

Conversion Factors Gallons per million gallons --- 1,000,000 l ---

Liters per gallon --- 3.7854 m ---

kilograms per milligram --- 0.000001 n ---

pounds per kilogram --- 2.205 o ---

Calculations

Daily TSS loading at max. concentration # / day 375.6 p b * h * l * m * n *

o

Filter area w/ avg. hydraulic loading ft2 320.6 q a / i

Filter area w/ max. hydraulic loading ft2 320.5 r c / j

Filter area w/ solids loading rate ft2 115.6 s p / k

Controlling Factor Minimum filter area required ft

2 320.6 t Max. (q, r, s)

Typical Equipment Configuration Disk Diameter ft 6 u ---

Disk submergence (area available for filtration) % 100% v ---

Number of sides per disk ea 2 w ---

Filter area available per disk ft2 per disk 56.55 x π * [(u/2)

2] * v * w

System Design Criteria Redundancy design parameter

(3) % 100% y ---

Total number of filter chambers ea 2 z ---

Minimum # of disks per chamber ea 5.67 aa t / x

Selected # of disks per chamber ea 6 bb ---

Total filter area per chamber ft2 339.29 cc x * bb

Total filter area (system) ft2 678.58 dd z * cc

NOTE 1: See Influent Lift Station calculations for peak flow & maximum pump flow through treatment components

NOTE 2: Hydraulic maximum flow represents an operator "error" condition where all 3 influent pumps are allowed to operate

NOTE 3: Engineer selects dual 100% reliability (i.e., establish two units, each capable of accommodating flow)

4.1.7.6 Redundancy

As required by paragraph 112.32 of the “Ten States Standards” the total filter area will be

provided in each of two units (i.e., dual 100% reliability) so that the required area is available with

one unit out of service.



4.1.8 UV Disinfection

4.1.8.1 Selection Preference

Due to extremely high capital costs, an ozone disinfection system is not selected. Due to

regulatory compliance difficulties, chlorine gas disinfection is not selected. Therefore, ultraviolet

(UV) disinfection is the recommended technology for a disinfection system.

4.1.8.2 Description

The UV disinfection will consist of a concrete channel with two (2) banks of ultra-violet (UV)

lamps. Ultraviolet radiation is an effective bactericide and virucide that avoids the use of chlorine as

a disinfectant. Information about UV technology is taken from page 351 of the Metcalf and Eddy

“Wastewater Engineering” third edition handbook (Exhibit No. 4). Mercury lamps are used because

the light output is at a wavelength of 253.7 nm, which is within the optimum range for germicidal

effects. For best results, the lamps are submerged in a flow channel.

4.1.8.3 System Performance Requirements

The required UV system performance characteristics are listed below:

Table 4-14

UV System Performance Characteristics

Feature Value or Quantity

Design Conditions

Average Flow 1.5 mgd

Peak Flow 3.0 mgd

Total Suspended Solids 30 mg/l

EPD Permit Limit for Fecal Coliform 200 (# per 100 ml)

Fecal Coliform at Inlet 126,000 (# per 100 ml)

Lamp Specifications

UV Wavelength 254 nm

Minimum UV Transmittance 65%


Several manufacturers make equipment of a quality required to provide acceptable service for

WWTPs such as Lyons North. These include Calgon, Wedeco, and Trojan. The system design is

based on the Calgon UV System. See the following table for the system description. A proposed

concept is found in Appendix VII.



Table 4-15

Summary of UV Equipment

Feature Value or Quantity

System Configuration

Number of Channels 1

Number of Banks per Channel 2

Number of Racks per Bank 2

Number of Lamps per Rack 4

Total Number of Lamps 16

Number of UV Sensors 2

Number of Power Distribution Centers 1

Number of Weirs 1

Hydraulic Considerations

Peak Velocity in Channel 27.85 inches / second

Headloss per UV Bank 2.06 inches

Headloss across Level Control Device 6 inches

Total Headloss across UV System 10.11 inches

Retention Time 3.79 seconds

Approximate Channel Dimensions

Length 377 inches

Width 12 inches

Width at Level Control Weir 30 inches

Depth 48 inches

Depth at Level Control Weir 46 inches

Effluent Depth in Channel 24 inches, nominal

4.1.9 Flow Measurement Weir (Combination Structure) A common structure will both store treated effluent for the Water Reuse System (see Section

4.4.1.2), and will also measure the facility’s effluent flow rate. The flow measurement function is

described in further detail in the section below.

4.1.9.1 Flow Measurement Weir Characteristics

An ultrasonic sensor will measure the depth of water and convert it to a flow rate for continuous

recording at a proposed flow measurement weir. Flow will be measured across a 120-degree V-

notch weir. The flow/head relationship is determined as:

Weir Formula

Q = 2.54 * h^

(5/2) * tan(Ɵ/2)

(Reference page 211 of "Hydraulics Handbook")

with,

Q = volume of flow (cfs)


Ɵ = degree of v-notch (degrees)



Flow Formula

Q = V * A

with,

V = velocity (fps)

A = area (ft.

2)

The formula is solved for various flow scenarios, as presented in the chart below. Resulting

heads range between 0.00 inches and 15.36 inches.

Flows across 120-degree v-notch Weir

Flow Description

Total Qeffluent (gpm)

Total Qeffluent (mgd)

Total Qeffluent (cfs)

head (ft)

head (in.)

Static -- No Flow 0 0.000 0.00

0.00 0.00

Facility Flow @ 20% WWTP Design Flow 208 0.300 0.46

0.40 4.80


0.47 5.64


0.53 6.36


0.58 6.96


0.63 7.56


0.67 8.04


0.70 8.40

WWTP Design Avg. Flow 1042 1.500 2.32

0.77 9.24

Flow w/ 1 influent pump operating non-stop 1125 1.620 2.51

0.79 9.48

WWTP Peak Flow 2083 3.000 4.64

1.02 12.24

Flow w/ 2 influent pumps operating non-stop 2250 3.240 5.01

1.05 12.60


1.23 14.76

Potential Flow w/ 3 influent pumps operating non-stop, based upon pump curve 3675 5.292 8.19

1.28 15.36

4.1.10 Effluent Cascade Effluent must have a minimum dissolved oxygen (D.O.) concentration of 6.0 mg/l to satisfy the

wasteload allocation requirements. The existing effluent cascade was originally designed with a 9.0’

height to reintroduce oxygen that increases D.O. levels from 0.0 mg/l to 6.0 mg/l (at 20° C), so it will

be retained. However, a hydraulic analysis will be performed to determine if a second cascade is

needed since the facility’s design flow rate will more than double. The existing cascade height is

presented below.

Top Step Elevation = 174.00’

Bottom Elevation = 165.00’

Height Available = 9.00’



4.1.10.1 Oxygenation Check

Formula from "MOP No. 8" on page 114-115

with,

r = deficit ratio

a = 0.8

b = 1.3

Cs = from Table C-3 (page 694) of "Environmental Engineering"

C0 = D.O. concentration of influent

C = D.O. concentration of effluent

T = Temperature, Celsius

r = (Cs - C0) / (Cs - C)

h = (r - 1) / {0.11 x a x b x [1 + (0.046 x T)]}

substituting,

r = {[0.11 x a x b x (1 + <0.046 x T>)] * h} + 1

C = Cs - {(Cs - C0) / r}

The formula is solved for various temperatures, as presented in the chart below. Resulting DO

concentrations vary between 6.09 mg/l and 6.80 mg/l for the normal temperature range of 10° to

20° C.



Temperature (Celsius) Cs (mg/l) h (ft.) r

C0 = Cin (mg/l)

C = Cout

(mg/l)

0 14.62 9.0 2.030 0.0 7.42

1 14.23 9.0 2.077 0.0 7.38

2 13.84 9.0 2.124 0.0 7.32

3 13.48 9.0 2.172 0.0 7.27

4 13.13 9.0 2.219 0.0 7.21

5 12.80 9.0 2.266 0.0 7.15

6 12.48 9.0 2.314 0.0 7.09

7 12.17 9.0 2.361 0.0 7.02

8 11.87 9.0 2.408 0.0 6.94

9 11.59 9.0 2.456 0.0 6.87

10 11.33 9.0 2.503 0.0 6.80

11 11.08 9.0 2.551 0.0 6.74

12 10.83 9.0 2.598 0.0 6.66

13 10.60 9.0 2.645 0.0 6.59

14 10.37 9.0 2.693 0.0 6.52

15 10.15 9.0 2.740 0.0 6.45

16 9.95 9.0 2.787 0.0 6.38

17 9.74 9.0 2.835 0.0 6.30

18 9.54 9.0 2.882 0.0 6.23

19 9.35 9.0 2.929 0.0 6.16

20 9.17 9.0 2.977 0.0 6.09

21 8.99 9.0 3.024 0.0 6.02

22 8.83 9.0 3.072 0.0 5.96

23 8.68 9.0 3.119 0.0 5.90

24 8.53 9.0 3.166 0.0 5.84

25 8.38 9.0 3.214 0.0 5.77

26 8.22 9.0 3.261 0.0 5.70

27 8.07 9.0 3.308 0.0 5.63

28 7.92 9.0 3.356 0.0 5.56

29 7.77 9.0 3.403 0.0 5.49

30 7.63 9.0 3.450 0.0 5.42

At 30° C, the 9.0’ high cascade would require an inlet D.O. concentration of 2.0 mg/l to achieve

an effluent D.O. concentration of 6.0 mg/l.



4.1.10.2 Hydraulic Check

Next, the hydraulic capacity of the effluent cascade will be checked for the design flow rates.

The designer’s goal is to limit the maximum water level on each step to 9 inches at peak flow (less

than step height). The Francis Formula for a rectangular contracted weir will be used to check the

hydraulic flows at the cascade. This formula is taken from page 211 of the “Hydraulic Handbook”

which is referenced as Exhibit No. 2.

Weir Formula -- (Francis formula for rectangular contracted weir)

Q = 3.33 * h^

(3/2) * [B - (0.2 * h)]

with,

Q = volume of flow (cfs)


B = length of weir crest (feet)

Flow Formula

Q = V * A

with,

V = velocity (fps)

A = area (square feet)

Constants B 2.5 (feet) -- to match existing step width



Flows across rectangular contracted weir

Flow Condition

Total Flow

Flow per Cascade

Water Depth & Velocity

Total Q (gpm)

Total Q (mgd)

Total Q (cfs)

# of Cascades

Cascade Q (cfs)

Cascade head (feet)

Cascade head

(inches)

Cascade velocity

(fps)

Option 1 - Single Effluent Cascade Static -- No Flow 0 0.000 0.00

1 0.00

0.000 0.00 ---


1 0.46

0.147 1.76 1.26


1 0.70

0.193 2.32 1.44


1 0.93

0.234 2.81 1.59


1 1.16

0.272 3.26 1.71


1 1.39

0.308 3.70 1.81


1 1.62

0.342 4.10 1.90


1 1.86

0.375 4.50 1.98


1 2.32

0.437 5.24 2.12


1 2.51

0.460 5.52 2.18


1 4.64

0.704 8.45 2.64


1 5.01

0.742 8.90 2.70


1 7.52

0.987 11.84 3.05


1 8.19

1.048 12.58 3.13



Flow Condition

Total Flow

Flow per Cascade

Water Depth & Velocity

Total Q (gpm)

Total Q (mgd)

Total Q (cfs)

# of Cascades

Cascade Q (cfs)

Cascade head (feet)

Cascade head

(inches)

Cascade velocity

(fps)

Option 2 - Dual Effluent Cascades Static -- No Flow 0 0.000 0.00

2 0.00

0.000 0.00 ---


2 0.23

0.092 1.10 1.01


2 0.35

0.121 1.45 1.15


2 0.46

0.147 1.76 1.26


2 0.58

0.170 2.04 1.37


2 0.70

0.193 2.32 1.44


2 0.81

0.214 2.57 1.52


2 0.93

0.234 2.81 1.59


2 1.16

0.272 3.26 1.71


2 1.25

0.287 3.44 1.75


2 2.32

0.437 5.24 2.12


2 2.51

0.460 5.52 2.18


2 3.76

0.608 7.30 2.47


2 4.09

0.645 7.74 2.54



CONCLUSION: Because the higher flows through a single cascade approach the 9-inch water

depth on each cascade step, select dual effluent cascades to limit the water depth to between 3.26

and 7.74 inches for average to potential peak 3-pump flows.

4.1.11 Outfall Pipe Based on a hydraulic analysis of the existing 12-inch outfall pipe, the pipe must be replaced with

a new 18-inch ductile iron pipe. See the calculations below for the analysis.

On the other hand, during final design it may be preferred or necessary to have dual outfall

pipes rather than a single new pipe. A new, second outfall pipe would be installed parallel to the

existing outfall pipe, which would remain in place.

Pipe Capacity Formula Qcapacity = {1.49/n} * {A} * {R

^(2/3)} * {S

^(1/2)}

with,

Manning's Roughness Coefficient, (n) = varies, per pipe material Radius, (r) = (Pipe Dia. / 2) Ft.

Area, (A) = π * r2 Ft.

2

Wetted Perimeter, (P) = 2 * π * r Ft.

Hydraulic Radius, (R) = (A / P) Hydraulic slope, S = assumed equal to pipe gradient



Table 4-16

Outfall Pipe Calculations

Characteristic Unit Existing Pipe Proposed

Replacement Pipe

Average Flow

mgd 1.500 1.500

gpm 1,042 1,042

cfs 2.32 2.32

Peak Flow

mgd 3.000 3.000

gpm 2,083 2,083

cfs 4.64 4.64

Maximum Flow Rate

mgd 5.292 5.292

gpm 3,675 3,675

cfs 8.19 8.19

Upstream pipe invert elevation MSL 165.00 165.00

Downstream pipe invert elevation MSL 156.10 156.10

Fall in pipe ft. 8.90 8.90

Pipe length ft. 612 612

Pipe gradient, sassumed % 1.45% 1.45%

Pipe status --- Existing Proposed

Pipe material --- CMP DIP

Manning's Roughness Coefficient, n --- 0.024 0.012

Pipe diameter in. 12 18

ft. 1.00 1.50

Pipe radius, r ft. 0.50 0.75

Area, A ft.2 0.785 1.767

Wetted perimeter, P ft. 3.14 4.71

Hydraulic radius, R ft. 0.250 0.375

Pipe capacity, Qcap cfs 2.33 13.76

gpm 1,047 6,175

mgd 1.508 8.893

Does pipe capacity exceed maximum flow rate? --- Not Acceptable Acceptable



4.2 Chemical Feed Processes The chemical feed processes introduce various chemicals from outside sources into the waste

stream for the purpose of improving the treatment performance.

4.2.1 Coagulation (Alum) To achieve even more stringent treatment levels of phosphorus than provided by the biological

treatment system (Section 4.1.5) and the secondary clarifiers (Section 4.1.6), provisions will be made

for phosphorus removal by precipitation. A chemical coagulant will be added to the wastewater to

promote flocculation which leads to either precipitation in the secondary clarifier or solids capture

at the filter. Three (3) separate feed locations will be established to give the operator flexibility, as

follows:

Ahead of the secondary clarifiers at each clarifier feed pipe

Ahead of the filter

Digester (to aid phosphorous-laden solids settling during decant operations)

According to page 160 of the “MOP No. 8” (Exhibit No. 6), the completion of the coagulation

reaction is almost instantaneous after the chemicals are fully dissolved. Thus, the chemical injection

points will be located immediately upstream of the target component (i.e., secondary clarifiers,

filter, or digester).

The remainder of Chapter 11 of “MOP No. 8” as well as Chapter 4 of “Phosphorous Removal

from Wastewater” (referenced as Exhibit No. 8) are used to design the chemical treatment system

for phosphorus removal.

Design texts describe four typical coagulants used for phosphorus removal: lime, alum, sodium

aluminate, and ferric chloride. At this point, the designer selects to use alum. Phosphorus removal

efficiencies in secondary treatment range from 80 to 95 percent. As described elsewhere in this

report, influent and effluent concentrations of phosphorus, without chemical precipitation, are as

follows:

Influent Phosphorus = 10 mg/l (See Table 3-01)

Effluent Phosphorus < 1 (such as 0.3) mg/l (See table 3-02)

Since the effluent limit is 1.0 mg/l (See Table 3-02), chemical precipitation is a backup method to

achieve phosphorus removal. The operator will be allowed to field-adjust chemical dosage

requirements based on jar test results. Typical dosage rates, according to page 62 of “Phosphorous

Removal from Wastewater” (Exhibit No. 8), are 1.5 parts of aluminum coagulant per part of total

phosphorus. The alum solution will be stored in a storage tank or tote, and it will be pumped to the

injection point through a diaphragm-type chemical feed pump.



4.2.2 pH Adjustment (Soda Ash)

4.2.2.1 Process Description

Alkalinity is consumed during nitrification and by alum. Alkalinity is partially recovered during

dentrification. If enough alkalinity is present in the wastewater to provide for the net consumption,

then no outside alkalinity is needed. Otherwise, alkalinity will need to be added to the system.

Approximately 70 to 80 mg/l of residual alkalinity must remain in the effluent to keep pH in the 7.0

range, as described on page 684 of “Wastewater Engineering – Treatment, Disposal, and Reuse”

(Fourth Edition) by Metcalf and Eddy, Inc.

4.2.2.2 Chemical Selection

The most commonly used chemicals used to control pH are listed in Table 6-15 of “Wastewater

Engineering – Treatment, Disposal, and Reuse” (Fourth Edition) by Metcalf and Eddy, Inc. The

designer selects to use sodium carbonate (Na2CO3), which is commonly known as soda ash.

4.2.2.3 Typical Alkalinity Loadings

Soda ash for alkalinity requirements will be provided based on typical influent alkalinity loadings

in the sewage available for process consumption. Typical loadings are shown below:

Table 4-17

Typical Alkalinity Strength

Characteristic Symbol Unit Value Description Reference

Alkalinity (as CaCO3)

Alk as CaCO3 mg / l

50 Typical input: weak

concentration

M&E (3rd) Table 3-15 100

Typical input: medium concentration

200 Typical input: strong

concentration

140 Engineer input DDR chapter 3.1 (1) (2)

General NOTE: M&E refers to "Wastewater Engineering Treatment and Reuse" (Fourth Edition) by Metcalf & Eddy General NOTE: M&E (3rd) refers to "Wastewater Engineering Treatment, Disposal, and Reuse" (Third Edition) by Metcalf & Eddy

General NOTE: The following shading cells are used in the spreadsheet:

1 Project design input or design selection

NOTE 1: Term Alk as CaCO3 is defined in Equation 2-36 (M&E)

NOTE 2: Alkalinity as CaCO3 loadings are assumed to be in the upper range due to groundwater withdrawals from limestone aquifers


The Biological Treatment System section (Section 4.1.5) summarized the design calculations,

which are shown in Appendix VI. These calculations included alkalinity requirements, and they are

re-produced on the following page for convenience:



(1.1 mgd Train)

(0.4 mgd Train)

Category Characteristic Symbol Unit Value Value (Input) or (Calculation) Reference Row

Alkalinity Addition

Flow Rate Q m3 / day 4,164 1,514 Project Input

See "Design Inputs" 242

Influent Alakalinity Alkinf (as CaCO3) mg / l 140 140

Use Alk as CaCO3 from Design Inputs

See "Design Inputs" 243

Concentration of influent NH4-N that

is nitrified NOX mg / l 28.7 28.7 Use NOX from Nitrogen Balance calculations

(10)

See "Nitrogen Balance"

calculations 244

Effluent NO3-N concentration Ne mg / l 6.0 6.0

Use NO3-N from Internal Recycle Ratio calculations

See "Internal Recycle Ratio" 245

Alakalinity consumed per

ammonia nitrogen converted to nitrate

Alk ratioconsumed

g Alkalinity (as CaCO3) /

g NH4-N converted 7.14 7.14 Alk ratioconsumed = 7.14

M&E Eqn. 7-89 & Ex. 8-5 (step

9) 246

Alakalinity produced

(recovered) per nitrate reduced

(denitrified) Alk

ratiorecovered

g Alkalinity (as CaCO3) /

g NO3-N reduced 3.57 3.57 Alk ratiorecovered = 3.57

M&E Eqn. 7-97 & Ex. 8-5 (step

9) 247

Residual Alkalinity required to remain neutral pH (+/- 7)

Alkresidual as (CaCO3) mg / l 80 80

Range is 70 - 80 mg / l (as CaCO3) M&E (pg. 684) 248

Alkalinity used during nitrification

Alkused (as CaCO3) mg / l 205.27 205.27

Alkused = Alk ratioconsumed * NOX

M&E Eqn. 8-5 (step 9) 249

Alkalinity produced during

denitrification Alkproduced (as

CaCO3) mg / l 81.21 81.21 Alkproduced = Alk ratiorecovered *

[NOX - Ne] M&E Eqn. 8-5

(step 9) 250

Alkalinity to be added (to maintain

neutral pH) Alkadded (as

CaCO3) mg / l 64.05 64.05 Alkadded = Alkresidual - Alkinf +

Alkused - Alkproduced M&E Eqn. 8-5

(step 9) 251

Mass of alkalinity to be added (to

maintain neutral pH)

Alkmass kg / d 267 97

Alkmass = Alkadded * Q * (1 kg / 1000 g)

M&E Eqn. 8-5 (step 9) 252

# / d 588 214 Conversion Factor = (2.205

lbs / 1 kg) calculation 253



4.2.2.5 Injection Locations

Soda ash injections will be established at the following locations:

Influent Lift Station

Digester

4.2.2.6 Conclusion

The alkalinity deficit (64 mg/l) is not within the buffering capacity of the system (80 mg/l).

Therefore, a soda ash injection system is proposed. However, the system does not have to be

operated during periods when the actual alkalinity buffering capacity exceeds the alkalinity

requirements.



4.3 Solids Handling Processes The solids handling processes include the sludge return required for treatment of the

wastewater, the solids reduction by digestion, and the solids removal from the facility by filter

pressing.

4.3.1 Activated Sludge Pumps The treatment process requires activated sludge to be drawn off the bottom of each train’s

secondary clarifier. Return Activated Sludge (RAS) is returned to the initial treatment

compartment, the Anaerobic Zone. Waste Activated Sludge (WAS) is wasted to the digester via the

digester splitter box. Both RAS and WAS will be lifted by air lift pumps that are internal to the

package plant and which use air from the facility’s blowers.

4.3.1.1 Return Activated Sludge (RAS) Pumps

Characteristics of the RAS pumps are presented below.

Table 4-18

Summary of RAS Pumps

Feature Description

Type Air lift pump (internal to package plant)

RAS Rate for 5-Stage Bardenpho Process 50% to 100% of influent flow rate (see Table 4-04)

QWWTP Average 1042 gpm

Train 1 (1.1 mgd)

QTrain 1 Average 1.100 mgd

QTrain 1 Average 770 gpm

RAS Flow Rate, minimum (50% of QTrain 1 Average) 385 gpm

RAS Flow Rate, maximum (100% of QTrain 1 Average) 770 gpm

Train 1 RAS Flow Rate Range 385 - 770 gpm

Discharge Location into Train 1 Anaerobic Basin

Train 2 (0.4 mgd)

QTrain 2 Average 0.400 mgd

QTrain 2 Average 280 gpm

RAS Flow Rate, minimum (50% of QTrain 2 Average) 140 gpm

RAS Flow Rate, maximum (100% of QTrain 2 Average) 280 gpm

Train 2 RAS Flow Rate Range 140 - 280 gpm

Discharge Location into Train 2 Anaerobic Basin

4.3.1.2 Waste Activated Sludge (WAS) Pumps

The same air lift RAS pumps will be used as waste sludge pumps to remove sludge from the

treatment system. A valve on the air lift discharge line will change the discharge to the Digester

Splitter Box.



4.3.2 Digester Splitter Box

4.3.2.1 Flow Description

The Digester Splitter Box receives sludge flows from multiple sources, and then distributes flows

out to different locations. Flows are received from:

Treatment Train 1 WAS

Treatment Train 2 WAS

Sludge Transfer Lift Station

The Digester Splitter Box distributes flows to the following components:

Digester Tank 1

Digester Tank 2

Existing Sludge Drying Beds (if they can be retained – see Section 4.3.6)

Overflow Pond

4.3.2.2 Box Description

Flow enters the Digester Splitter Box at the upper deck where it is blended together. Four (4)

separate control gates can be raised independently to direct flow out of the upper deck to

individual distribution chambers. Each chamber is dedicated to one of the outlet locations

identified in the section above. Because the control gates are not 100% water tight, and because

rain water may fall directly into the distribution chambers, the distribution outlet pipes (except for

the overflow pond pipe) will have a plug valve that allows the operator to fully prevent flow to the

downstream component.

An emergency overflow pipe will be installed above the normal high water level of the upper

blending deck. The overflow pipe will prevent spills by directing flow to the overflow pond.

4.3.3 Aerobic Digestion

4.3.3.1 Digester Description

It is proposed to construct two (2) separate circular aerobic digester tanks to provide for

digestion, supernatant separation, sludge concentration, and any necessary sludge storage in

accordance with the requirements of Paragraph 85 of the ”Ten States Standards” (Exhibit No. 5).

In addition, provisions will be made for scum/grease removal and emergency high-level overflow.

The two (2) separate tanks will function as a 2-stage digester. The 2-stages allow for additional

sludge thickening since periodic decanting will increase the solids concentration in one tank. Also,

two separate stages allow the operator to keep air in one tank while the other tank is decanted,

and vice versa, thereby reducing the potential for odor or for phosphorous release. Finally, the 2-



stages satisfy the “Ten States Standards” recommendation for multiple digestion units capable of

independent operation for plants exceeding 100,000 gpd.

Supernatant Separation (Decanting Operations)

Air will be turned off in one tank or the other to create quiescent conditions within the digester.

After solids have settled a telescoping valve will draw off supernatant from the water surface and

discharge it for recirculation to the head of the plant. The telescoping collection line valve to the

influent lift station will be opened. Provisions will be made for an alternate supernatant discharge

to the overflow pond.

Scum and Grease Removal

The same telescoping valve used for decanting operations will periodically draw off floating

scum and grease. The telescoping collection line valve to the belt press will be opened for

discharge to the belt press and removal from the plant. The scum and grease can be blended with

the sludge during this operation.

High Level Emergency Overflow

A static emergency overflow pipe will be installed at each digester tank in order to prevent

accidental spills. Each pipe will discharge to the overflow pond.

4.3.3.2 Expected Sludge Properties

Much of the sludge discussion is originally presented on pages 765-777 of “Wastewater

Engineering – Treatment, Disposal, and Reuse” (Third Edition) -- Exhibit No. 4. Two (2) types of

sludge which will be generated at the WWTP are described below:

1. Activated Sludge

Activated sludge generally has a brownish, flocculant appearance. If the color is dark, the sludge may be approaching a septic condition. If the color is lighter than usual, there may have been underaeration with a tendency for the solids to settle slowly. Sludge in good condition has an inoffensive “earthy” odor. The sludge tends to become septic rapidly and then has a disagreeable odor of putrefaction. Activated sludge will digest readily alone or when mixed with primary sludge.

2. Sludge from Chemical Precipitation

Sludge from chemical precipitation with metal salts is usually dark in color though its surface may be red if it contains much iron. Lime sludge is grayish brown. The odor of chemical sludge may be objectionable, but is not as bad as primary sludge. While chemical sludge is somewhat slimy, the hydrate of iron or aluminum in it makes it gelatinous. If the sludge is left in the tank, it undergoes decomposition similar to primary sludge, but at a slower rate. Substantial quantities of gas may be given off and the sludge density increased by long residence times in storage.



Typical sludge characteristics and quantities are described in Exhibit No. 4 and are summarized

in the following table.

Table 4-19

Typical Sludge Characteristics

Sludge Characteristic Unit

Treatment Process

Activated Sludge (waste sludge)

Extended Aeration (waste sludge)

Specific gravity of sludge solids --- 1.25 1.30

Specific gravity of sludge --- 1.005 1.015

Dry solids range lbs. / 1,000

gallons 0.6 to 0.8 0.7 to 1.0

Typical dry solids lbs. / 1,000

gallons 0.7 0.8

Range of sludge solids concentration % dry solids 0.8% to 2.5% 0.8% to 2.5%

Internal Recycle % dry solids 1.3% 1.3%

Sludge is then wasted to the digester for continued stabilization and thickening.

4.3.3.3 Sludge Quantity Calculations

According to page 176 of “MOP No. 8” (Exhibit No. 6), chemical addition of metallic salts

typically increase sludge production by 50% over that produced in biological treatment. The

calculations below estimate the quantity of sludge generated.

Quantity of Biological Activated Sludge

Volume of Biological Sludge = (Ws ) / (ρw x Ssl x Ps )

= See Equation 12-2 in Exhibit No. 4

where,

Ws = weight of dry solids, lb.

= Q x (SSi x SSe ) x 8.34

Q = 1.5 mgd

SSi = Suspended Solids, influent

= 350 mg/l (See Table 3-01)

SSe = Suspended Solids, effluent

= 5 mg/l (use 5, not 20 from Table 3-02)



Conversion Factor, 8.34 = [1,000,000 gallons / million gallons]

x [3.7854 liters / gallons]

x [1 kg / 1,000,000 mg]

x [2.205 # / 1 kg]

= 8.34

Ws = 1.5 x (350-5) x 8.34

= 4,314 #/day

ρw = density of water, lb./ft.3

= 62.4 lb./ft.3

Ssl = specific gravity of the sludge

= 1.03 (Typical digestion value)

Ps = percent solids expressed as a decimal

= 0.02 (2.0% typical following digestion)

Substituting for the sludge volume formula, and using the conversion factor of 7.48 gallons per

cubic foot,

Volume of Biological Sludge = (4,314)/(62.4 x 1.03 x 0.02)

= 3,356 ft.3 / day (at 2.0% solids)

= 25,100 gallons/day

Quantity of Chemical Precipitation Sludge

Volume of Chemical Sludge = 50% x Volume of Biological Sludge

= 0.5 x 3,356 ft.3

= 1,678 ft.3 / day


Total Quantity of Sludge

Total Sludge Volume = (Biological Sludge) + (Chemical Sludge)

= (25,100 gpd) + (12,550 gpd)




4.3.3.4 Storage Requirements for Digester

For potential land application of the sludge in the future in lieu of the landfill option, the U.S.

EPA 503 Regulations would have to be met. The regulations require the Class B sludge to meet

Pathogen reduction criteria and to meet Vector Attraction reduction criteria. According to pages 18

through 21 of the “EPA Process Design Manual for Land Application of Sewage Sludge and

Domestic Septage” (Exhibit No. 9) which was published September, 1995, both the pathogen

reduction and the vector attraction reduction requirements can be met with the use of an aerobic

digester. Table 3-12 allows a digester size of 40 days at 680 F, and it allows a digester size of 60 days

at 590 F. Section 3.4.2.3 provides an option to meet vector attraction reduction requirements by

having an additional 30 days of digestion for sewage sludge that has been digested for 20 days.

Therefore, a 50-day digester will be provided at a minimum.

4.3.3.5 Digester Volume Calculations

Two (2) separate volume calculation methods will be evaluated in the following sub-sections,

and the different results will be reconciled.

4.3.3.5.1 Method 1 Volume Calculations

Method 1 will multiply the total sludge volume produced daily by the number of storage days

desired.

Digester Volume = (Total Sludge Volume) x (Storage Days)

= (37,650 gpd) x (50 days)

= 1,882,500 gallons

4.3.3.5.2 Method 2 Volume Calculations

Method 2 will calculate the digester storage volume based on the “Ten States Standards”

requirements. The total volume will be the sum of the aerobic digestion tank plus the sludge

storage requirements.

Aerobic Digestion Tank Capacity

Paragraph 85.31 of the ”Ten States Standards” provides a guide for sizing the digestion tank

volume based on the following assumptions:

2% feed solids concentration

Digester temperature of 59 ºF (15 ºC)

Solids retention time of 27 days

If supernatant separation is performed in the digester tank, 25% additional volume is

required.

Additional volume may be needed for land application disposal

Digestion volume is equal to 3.0 ft.3 per population equivalent (P.E.) for extended aeration

activated sludge



Digestion Baseline Volume = (WWTP Population Equivalent) x (3.0 ft.3 / P.E.)

with,

WWTP Population Equivalent = (WWTP Design Flow) / (Per Capita Use)

WWTP Design Flow = 1,500,000 gallons per day

Per Capita Use = 150 gallons per day per capita (assumed)

WWTP Population Equivalent = (1,500,000 gpd) / (150 gpd / capita)

= 10,000 capita

Digestion Baseline Volume = (10,000 capita) x (3.0 ft.3 / P.E.)

= 30,000 ft.3

= 224,400 gallons

Increase digester volume by 25% to account for supernatant separation within digestion tank.

Digestion Volume = (Digestion Baseline Volume) x 125%

= (224,400 gallons) x 125%

= 280,500 gallons

Sludge Storage

Section 85.91 of the ”Ten States Standards” requires storage to accommodate daily sludge

production volumes and as an operational buffer for unit outage and adverse weather conditions.

Further reference is made to Paragraphs 85.8 and 89.12. Sludge storage requirements are

calculated below.

Sludge Storage Volume, dry = (Sludge production) x (Storage days required)

with,

Sludge production = (Sludge production value) x (P.E.)

Sludge production value (dry weight basis) = See Section 85.8

= 0.16 lb. / P.E. / day



P.E. = Population Equivalent

= 10,000 capita (see calculations above)

Sludge production = (0.16 lb. / P.E. / day) x (10,000 P.E.)

= 1,600 lb. / day

Storage days required = 120 to 180 days (see Section 89.12)

= Use 120 days

Sludge Storage Volume, dry = (1,600 lb. / day) x (120 days)

= 192,000 lbs. (dry)

The sludge storage volume values are based on a maximum solids concentration of 2 percent.

Therefore, if the sludge is stored in a liquid tank, the solid sludge represents a wet volume as

calculated below.

Sludge Volume, wet = (Sludge storage weight, wet) / (liquid weight per gallon)

with,

Sludge Storage Weight (wet) = (Dry Storage Volume) / (Solids Concentration)

= (192,000 lbs., dry) / (2%)

= 9,600,000 lbs., wet

Liquid weight per gallon = 8.34 lbs. / gallon

So,

Sludge Volume, wet = (9,600,000 lbs.) / (8.34 lbs. / gallon)

= 1,151,080 gallons

Liquid Storage

Section 85.92 of the ”Ten States Standards” requires liquid sludge storage volumes as

calculated below.

Liquid Storage Volume = (Daily Volume) x (Storage days required)



with,

Daily Volume = (Daily Volume Production) x (P.E.)

Daily Volume Production = See Section 85.92 for WAS

= 0.13 ft.3 / P.E. / day

P.E. = Population Equivalent

= 10,000 capita (see calculations above)

Storage days required = 120 (see selection above)

Daily Volume = (0.13 ft.3 / P.E. / day) x (10,000 P.E.)

= 1,300 ft.3 / day

= 9,724 gallons per day

Liquid Storage Volume = (9,724 gpd) x (120 days)

= 1,166,880 gallons

Reconcile Liquid Storage

Sludge Volume, wet = 1,151,080 gallons (from above)

Liquid Storage Volume = 1,166,880 gallons (from above)

Use the average,

Liquid Storage Volume = 1,158,980 gallons

Digester Volume Calculations (Method 2)

Digester Volume = (Digestion Tank Vol.) + (Liquid Storage Volume)

= (280,500 gallons) + (1,158,980 gallons)

= 1,439,480 gallons



4.3.3.5.3 Reconciled Volume Calculations

The two (2) methods for estimating the digester volume must be reconciled. Since the two

methods are in general agreement, the average volume requirements will be selected.

Digester Volume per Method 1 Estimate = 1,882,500 gallons

Digester Volume per Method 2 Estimate = 1,439,480 gallons

Average Digester Volume (avg. of 2 methods) = 1,660,990 gallons

Select Digester Volume for Design = 1,500,000 gallons

4.3.3.6 Air Calculations

Based on the “Ten States Standards”, paragraph 85.5, an air supply of 30 CFM per 1,000 ft.3 of

tank volume shall be provided with the largest blower out of service. See section 4.3.3.7 for a

preliminary tank volume size.

Aerobic Digestion Air Requirement = (30 CFM / 1,000 ft.3 )

x (1,508,000 gallons)

x (1 ft.3 / 7.48 gallons)

= 6,048 CFM

Blowers

Provide three (3) blowers each with an air supply capacity of 3,000 CFM. Two (2) blowers will be

able to supply the peak air flow requirements in the event that the 3rd blower is out of service.

Because of fluctuations in discharge pressure associated with different digester water levels (tank 1

vs. tank 2; and either tank on one day vs. another day), the blowers will be positive-displacement (P-

D) type. Each blower will have turn-down output capability in order to be energy efficient.

Air Diffusers

Coarse bubble diffusers will distribute the air within the digester. The air piping will be valved so

that either tank can be isolated from the other for decanting operations.



4.3.3.7 Preliminary Digester Summary

A potential digester layout and equipment summary are presented below.

Table 4-20

Digester Tank Preliminary Design Summary

Feature Description

Number of Tanks 2

Minimum Freeboard 1' - 9"

Proposed Side Water Depth 15' - 0"

Tank Diameter 92' - 6"

Tank 1 Volume 754,000 gallons

Tank 2 Volume 754,000 gallons

Total Digester Volume 1,508,000 gallons

Decanting Method by telescoping valve

Air System P-D blowers

Diffuser Type coarse bubble

Inlet Connection from Digester Splitter Box

Transfer from one tank to other via Sludge Transfer LIft Station

Drain to Sludge Handling Facility (belt press)

Overflow to Overflow Pond

4.3.4 Sludge Transfer Lift Station Based on the designer’s preference, it is desirable for the operator to be able to transfer the

contents from a full digester tank over a 24 to 36 hour period. Other factors, such as force main size

and pump horsepower, will be considered to make the final station capacity selection.

Calculations

Transfer Flow Rate = (Digester Tank Volume) / (Target Transfer Time)

with,

Digester Tank Volume = 754,000 gallons (see previous section)

Target Transfer Time, minimum = (24 hours) x (60 minutes/hour)

= 1,440 minutes

Target Transfer Time, maximum = (36 hours) x (60 minutes/hour)

= 2,160 minutes



Target Transfer Flow Rate (min.) = (754,000 gallons) / (2,160 minutes)

= 349 gpm

Target Transfer Flow Rate (max.) = (754,000 gallons) / (1,440 minutes)

= 524 gpm

Station Capacity Design Selection

The design sludge transfer lift station capacity is 425 gpm.

Discharge Location

The sludge transfer lift station will pump sludge to the Digester Splitter Box.

Type of Pump Station

The sludge transfer pumps could be either submersible (NOTE: top of wetwell must be set at

digester top elevation to prevent overtopping), or self-priming centrifugal (i.e., Gorman-Rupp).

4.3.5 Sludge Handling Facility


A belt filter press will de-water the sludge. Capacity requirements for the belt press are shown

below.

Table 4-21

Belt Filter Press Design Calculations

Feature Unit Value Reference

Total daily sludge volume gpd 37,650 DDR Section 4.3.3.3

Weekly sludge volume gal / week 263,550 (Total daily sludge volume) x (Weekly

sludge volume)

Proposed press operations, maximum

days / week 5 Engineer selection

hours / day 6

hours / week 30 (Press operations, days/week) x

(Press operations, hours/day)

minutes / week 1800 (Press operations, hours/week) x (60

minutes/hour)

Proposed press operations, minimum

days / week 2.5 Engineer selection (2 to 3 days per week average, say, 2.5) hours / day 6

hours / week 15 (Press operations, days/week) x

(Press operations, hours/day)

minutes / week 900 (Press operations, hours/week) x (60

minutes/hour)

Required press rate, minimum gpm 146 (Weekly sludge volume) / (Press

operations, max.)

Required press rate, maximum gpm 293

(Weekly sludge volume) / (Press operations, min.)



4.3.5.2 System Performance Requirements

The required belt filter press performance characteristics are listed below. See Appendix VIII for

a typical equipment brochure.

Table 4-22

Belt Filter Press Typical Performance Characteristics

Feature Unit Parameters

Type Skid-mounted belt filter press

Width meter 2.0

Solids capacity dry lbs. / hour approx. 1,500

Hydraulic capacity gpm 300

Feed solids concentration weight, % approx. 2% to 8%


Several manufacturers make equipment of a quality required to provide acceptable service.

These include BDP, among others.

4.3.6 Sludge Drying Beds The existing wastewater treatment facility has sludge drying beds located south of the Overflow

Pond. Total drying bed area is 3,600 ft.2. The final grading design of the upgrade and expansion

project will determine whether or not the beds can be salvaged. If they are salvaged, they will be

used as a backup to the new belt press.



4.4 Side Stream Processes Miscellaneous side stream processes are proposed. These include an on-site water reuse

system, an overflow pond, and a pond withdrawal station.

4.4.1 Water Reuse System An on-site water reuse system will supply wash water for several unit processes. The source

water for the reuse system will be treated effluent. Advantages of utilizing a reuse system include:

not introducing potable water into the WWTP, which would take away the flow allocated

for wastewater treatment

not having to produce potable water from the drinking water system

The sub-sections below describe the various features of the water reuse system.

4.4.1.1 Reuse Water Flow Demand

A preliminary water demand analysis is presented below.

Table 4-23

Preliminary Estimate of Reuse Water Demand Flow

Component Estimated Flow

Rate (gpm)

Estimated Pressure

Requirements (psi) Source of Estimate

Belt Press 125 60 Typical Equipment

Data

General washdown water (yard hydrants) 50 60 Engineer's goal

Total 175

NOTE: Flows and pressures will be confirmed during final design.

4.4.1.2 On-Site Reuse Water Reservoir (Combination Structure)

A common structure will both measure the facility’s effluent flow rate (see Section 4.1.9), and

will also store treated effluent for the water reuse system. The water storage function is described

below.

Location

The reservoir structure will be located following the UV system. If no reuse water is being

pumped, effluent will pass through the reservoir and over the flow measurement weir. If the reuse

pumps are operating, water will be drawn out of the reservoir (and less water will travel over the

flow measurement weir). When the forward plant flow between the UV system and the reservoir

exceeds the reuse pumping rate, some effluent will continue across the flow measurement weir.

When the forward plant flow between the UV system and the reservoir is less than the reuse



pumping rate, the effluent flow rate across the flow measurement weir will eventually stop as the

water level drops below the weir elevation.

Storage Volume

The reservoir storage volume will be sized to reduce the likelihood of “running dry” during low-

or no-flow periods. It is proposed to have a minimum of 10 minutes storage available for all uses,

and to have an additional 60 minutes of storage for the belt press since it runs continuously. After

60 minutes of operation, the belt press wash down water should be circulating back through the

plant and replenishing the reservoir storage, even if no additional effluent is flowing (i.e., during the

proverbial middle of the night). If some event, such as the influent lift station being off-line, reduces

forward flow through the plant, then the operator needs to reduce his on-site reuse demand.

An imbedded reservoir storage volume safety factor is available since the wastewater treatment

facility will typically have effluent entering the reservoir during those periods when the reuse pumps

are operating. On days when the local, high-water using industry (Chicken-of-the-Sea) is closed, the

expected minimum WWTP flow will be approximately 300,000 gpd, or 208 gpm. Because of the

large treatment tank storage volumes, peak flows are dampened out, and the effluent flow rate

approaches a steady rate, so the flow rate is not likely to stop altogether. Therefore, whatever the

effluent flow rate is becomes a margin of safety against “running dry.”

The proposed reservoir storage volume is estimated below.

Reservoir Volume Required = (Storage for all uses) + (Additional storage for belt press)

= (10 min. x 175 gpm) + (60 min. x 125 gpm)

= 9,250 gallons

4.4.1.3 Booster Pumps & Tank

Booster pumps will pressurize the non-potable reuse water system. There will be one service

pump and one standby pump. A pump will automatically be called to run when the reuse system

pressure drops to a pre-set amount, such as 45 psi. These pumps will discharge into a bladder (i.e.,

hydro-pneumatic) tank that maintains system pressure via an air compressor. The pumps will shut

off when pressure reaches a pre-set amount, such as 60 psi. The tank will be sized to prevent short

on/off/on/off/... pump cycles.

4.4.1.4 Reuse Water Main

The reuse water system pipes will be purple to reduce the potential of cross-connection with

the potable water mains.



4.4.2 Overflow Pond The existing pond will be retained for use as an overflow pond. This pond allows the influent lift

station peak sizing to be reduced, which in turn allows for steadier flows through the remainder of

the treatment plant. Other potential uses include temporary storage to bypass some or all

treatment basins, or to temporarily store solids, etc. Flow out of the pond can be returned to the

head of the plant for treatment via the pond withdrawal station.

The approximate overflow pond storage volume is estimated at 10 million gallons, based upon

the following characteristics:

5.40 foot depth (162.20’ water surface - 156.80’ bottom elevation)

247,500 ft.2 surface area (approximate)

1,336,500 ft.3 volume (approximate)

7.48 conversion factor (gallons per cubic foot)

4.4.3 Pond Withdrawal Station A pond withdrawal station will be located between the overflow pond and the influent lift

station. The pond withdrawal station is actually a valve station where individual valves are operated

via handwheels situated above ground for operator convenience. The valves can be opened to

allow pond water to drain back into the influent lift station, or can remain closed to isolate the

overflow pond from the influent lift station. Multiple drain pipes can be installed, such as at low-,

mid-, and high- water level. The different pipes draw water from different water strata within the

overflow pond.

If one or more valves are opened for a long enough period of time, the influent lift station water

level may equalize with the overflow pond. Alternately, the operator may choose to partially open a

valve at strategic times in order to “bleed” the pond contents through the influent lift station and

into the WWTP.


Buildings 5- 1

5 Buildings

5.1 Convert Existing Control Building into Operations Building The existing control / blower building will be gutted and converted into a full-size mechanical,

electrical, and chemical operations building. The existing blowers will be removed and replaced

with an array of new blowers that discharge into air piping. A space will be created for an electrical

and/or motor control center room. Storage space will be created to house chemicals. The building’s

roof will be rehabilitated, and new HVAC systems will be installed.

5.2 New Control Building A new control building will be constructed on-site. The new building will house the following

spaces:

Operator office

Process control / computer room

Laboratory

Personnel restroom and changing room

Indoor storage room.


Phased Construction 6- 1

6 Phased Construction The existing wastewater treatment plant will continue to operate during the upgrade and

expansion project. Therefore, it will be possible to construct the new 1.1 mgd treatment train while

the existing treatment plant remains in service. Once the 1.100 mgd treatment train is

commissioned, the existing plant can be taken off-line to be gutted and re-constructed into a 0.400

mgd treatment train.

The identified key construction phasing items are the demolition of the existing blowers and

replacement with new blowers, and maintaining the existing motor control center while blower

room demolition occurs. The contractor will have to first construct a new electrical room, then

convert half of the blower room at a time.

Alternately, the contractor may be able to temporarily install a new blower for the 1.1 mgd train

while the entire building is retrofitted at once. The temporary location can even be outside for 2-3

months during construction.

Meanwhile, other components (such as new digesters, filters, UV systems, control building, etc.)

can be constructed in any sequence without disrupting on-going treatment operations.

Because of the sequential nature of the construction, and because of the amount of

construction activities required, the project schedule needs to be a minimum of 12 months, and

potentially up to 18 months. Prior to advertising for bids, the Design Engineer will share the

construction plans with others in the construction community to assign an optimum construction

contract time length.


Points of Compliance 7- 1

7 Points of Compliance Influent constituent samples will be collected upstream of the influent screen. However,

influent flow measuring cannot be measured independently for the following reasons:

Head (i.e., water levels) upstream of the influent screen is under the influence of screen

operations. Therefore, a representative flow vs. head relationship cannot be developed.

Some facility influent will pass through the influent lift station and into the overflow pond.

Therefore, some volume of influent on a given day may not enter the wastewater treatment

plant treatment train.

Some volume of stored overflow pond water will enter the influent lift station on a given

day. Therefore, the total flow entering the treatment train is not representative of that

day’s influent flow.

Influent lift station pump output is not representative of the daily inflow since on-site

returns (as well as overflow pond returns, as mentioned above) cycle back through the

influent lift station.

The operator may measure separate data for his use, although this information does not have to

be reported to EPD. Examples of this data include:

Pump run times

MLSS concentrations

Overflow pond water level

Chemical feed

Etc.

Total facility flow will be measured at the flow measurement weir ahead of final discharge.

Effluent constituent samples will be collected at the bottom of the cascades.


Standby Power 8- 1

8 Standby Power A generator will be provided on-site to operate critical equipment in the event of power outage.

Loads from less critical components will be shed depending upon final generator sizing. Critical

equipment sizing is listed below:

Influent screen

Influent lift station (one pump, minimum)

Treatment basin blowers

Filter backwash system

UV Disinfection system

APPENDIX I

East WWTP NPDES Permit No. GA0033405

APPENDIX II

North WWTP NPDES Permit No. GA0033391

APPENDIX III

Georgia EPD Wasteload Allocation – June 27, 2016

APPENDIX IV

Influent Screen Concept

APPENDIX V

EVOQUA Concept and Calculations

(Train 1)

(Train 2)

APPENDIX VI

Treatment Design Calculations

APPENDIX VII

UV System Concept

APPENDIX VIII

Typical Belt Press Brochure

APPENDIX IX

Chemical Oxygen Demand Fractions of Municipal Wastewater for Modeling of

Wastewater Treatment

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