Stormwater Management for Highway Projects Regulatory Environment And Tools
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Transcript of Stormwater Management for Highway Projects Regulatory Environment And Tools
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Stormwater Management for
Highway Projects
Regulatory EnvironmentAnd
Tools
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Overview of Water Quality Issues
• Regulation of stormwater is a national issue
• Runoff from impervious surfaces recognized as a major contributor to degradation of stream quality
• Copper has been shown to harm salmonids at very low concentrations
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ESA Issues
Stormwater has become a major impediment to efficient ESA consultation process due to:
• Changing criteria for effect determinations in ESA Section 7 consultations
• Potential extension of the “action area” from the point of discharge to the sea
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Effect determinations• NMFS is basing Effect
Determinations on the quality of the stormwater at the point of discharge
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NMFS has provided written guidance for effect determinations
LAA: – New “pollutant generating
impervious surface” that discharges to surface waters:•Travel lanes•Shoulder widening•Turn lanes
Effect determinations
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Effect determinations
NLAA• All stormwater from the Water
Quality Design Storm is infiltrated
No Effect• Non-Pollutant generating surfaces
– Sidewalks– Guardrail flares– Separated bike paths
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Action AreaMost Recent NMFS Definition (or lack
thereof)– Potentially from point of discharge to
the ocean or major confluence (default)– Determined on a project-by-project basis
Just because there are no listed fish in the immediate project area does not mean that
a BA is not needed
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Action AreaODOT has proposed determining the
Action Area based on a “defining concentration” resulting from dilution of the highway runoff
FHWA is reviewing the proposal
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DEQ 401 Certification
• Heightened scrutiny of projects for 401 certification
• Increased attention to the protection of “Beneficial Uses”
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DEQ 401 Certification
“Beneficial Uses” is interpreted to give DEQ the responsibility to evaluate a projects impacts to more than simple water quality:– Riparian impacts– Channel modification– In-water work windows– Wetland impacts– Hydrologic impacts
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DEQ 401 Certification
Focus on providing stormwater treatment
“To the Maximum Extent Practicable”
No real definition available: DEQ is being sued over its interpretation
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ODOT/DEQ Streamlining Performance Standard: Goals
• Meet State WQ Standards • Don’t increase the pollutant load
when practicable• Decrease the pollutant load when
feasible• Manage the hydrology to prevent
harm to the receiving water and its channel
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ODOT/DEQ Streamlining Performance Standard: Objectives
• Infiltrate project stormwater• Treat at a minimum 140% of the new
impervious surface area• Treat the WQ design storm• Don’t put treatment into sensitive
resource areas• Prevent erosion by stormwater• Maintain pre-project hydrology• Provide for adequate maintenance of
facilities
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ODOT and the Resource and Regulatory agencies have collaboratively developed a pragmatic approach to improve stormwater management and facilitate permitting:
Focus on effective treatment, not numerical standards
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Water Quality Design Storm
Oregon Climate Zones
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Water Quality Design Storm
Table 1. Definition of Water Quality Design StormZone Factor (Percentage) x
2-yr, 24-hour rainfall depth at project location1 50 %2 50 %3 50 %4 67 %5 75 %6 50 %7 50 %8 50 %9 67 %
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Flow Control Design Storms
• These are the smallest and largest storms that are subject to hydrologic modification
• Hydrologic modification has two goals:– Protection and
maintenance of channel processes
– Flood control
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Flow Control Design StormLower Discharge Endpoint• Western OR - 42 percent of the 2-year, 24
hour event• Southeast, Northeast, North Central
Regions: 48 percent of the 2-year, 24 hour event
• Eastern Cascades Region: 56 percent of the 2-year, 24 hour event
Upper Discharge Endpoint• Minimally incised streams - Channel bank
overtopping event • Incised Streams -10-year/24-hour storm
event
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Flow Control Design Storm
Proposed threshold of concern :• Flow control does not need to be
addressed if the project increases the 10 year 24 hour storm discharge by less than 0.5 cfs
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BMP Selection Tool• The selection of treatment techniques and
strategies is supported by the BMP Selection Tool
• The Selection Tool is to help designers find the most effective treatment that is suitable for an individual project
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BMP Selection
• Key selection criteria (metrics)– Treatment capability– Physical site suitability– Maintenance – Resources, risk and public perception– Cost
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Treatment Mechanism – Target Pollutant Matrix
Mechanism
Hydrologic Attenuation
Density Separation
Sorption
Filtration
Uptake/Storage
Microbial
Transformation
Target Pollutan
t
Sediment/Particulate ■ ■ ■
Nutrients ■ ■ ■ ■
Oil and Grease ■ ■ ■ ■ ■
PAHs ■ □ ■ □ ■ ■
Metals (particulate) ■ ■ ■
Metals (dissolved) ■ ■ □ □ □
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Oil
Cont
rol F
acili
ties (
pret
reat
men
t)
Sedi
men
t Con
trol (
pret
reat
men
t)In
filtra
tion
trenc
h/po
ndBi
oret
entio
nBi
oslo
pePo
rous
Pav
emen
t (no
t sta
nd-a
lone
)G
rass
Sw
ale (
soil
amen
ded)
Filte
r Stri
p (so
il am
ende
d)G
rass
Sw
ale (
no so
il am
endm
ent)
Filte
r Stri
p (n
o soi
l am
endm
ent)
Cons
tructe
d W
etla
nds
Exte
nded
Det
entio
n D
ry P
ond
Wet
Pon
dsW
et V
aults
Med
ia Fi
lters
(non
-pro
prie
tary
)Pr
oprie
tary
Sep
arat
ion
(pre
treat
men
t)Pr
oprie
tary
Filtr
atio
n Fa
ciliti
es
Soil
Amen
dmen
tsCa
tch B
asin
Inse
rts
Hydrologic Attenuation ■ ■ ■ ■ □ □ □ □ □ ■ □ ■
Density Separation ■ ■ □ □ □ □ □ □ □ ■ ■ ■ ■ ■ □Sorption □ □ ■ ■ ■ ■ □ □ ■ □ □ □ □ ■ ■ □Filtration □ □ ■ ■ ■ ■ ■ ■ ■ □ □ □ ■ □ ■ ■ ■Uptake/Storage(1) □ ■ □ □ □ □ □ ■ □ □Microbial Transformation(1) □ ■ □ □ □ □ □ ■ □ □ □ □ □
Sediment/Particulate ○ ● ● ● ● ○ ● ● ● ● ● ● ● ○ ● ● ● ● ●Nutrients ● ● ● ○ ○ ○ ○ ○ ● ○ ○ - ○Oil and Grease ● ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ● ○ ○ ●Polycyclic Aromatic Hydrocarbons (PAH) ● ● ● ○ ○ ○ ○ ○ ● ○ ○ ○ ○Metals (particulate) ○ ○ ● ● ● ○ ● ● ● ● ● ● ● ○ ● ● ● ● ●Metals (dissolved) ● ● ● - ● ● ○ ○ ● ○ ○ ○ ● ●
Trea
tmen
t Mec
hani
smTa
rget
Pol
luta
nt
Treatment Mechanism - BMP Matrix
Best Management PracticePre
treatment Infiltration Filtration Pool-PondsSpace-constrained
or Urban
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Oil
Cont
rol F
acili
ties (
pret
reat
men
t)
Sedi
men
t Con
trol (
pret
reat
men
t)
Infil
tratio
n Fa
ciliti
es (t
renc
h/po
nd)
Bior
eten
tion
Bios
lope
Poro
us P
avem
ent (
not s
tand
-alo
ne)
Gra
ss S
wal
e (so
il am
ende
d)
Filte
r Stri
p (so
il am
ende
d)
Gra
ss S
wal
e (no
soil
amen
dem
ent)
Filte
r Stri
p (n
o soi
l am
endm
ent)
Wet
land
s
Exte
nded
Det
entio
n D
ry P
ond
Wet
Pon
ds
Wet
Vau
lts
Med
ia Fi
lters
(non
-pro
prie
tary
)
Prop
rieta
ry S
epar
atio
n Fa
ciliti
es *
Prop
rieta
ry Fi
ltrat
ion
Facil
ities
*
Surface Area (↑ is greater area) ↓ ↓ ↔ ↓ ↔ ↓ ↔ ↔ ↔ ↔ ↑ ↑ ↑ ↓ ↔ ↓ ↓Drainage Area (↑ is greater area) ↓ ↓ ↑ ↓ ↔ ↓ ↔ ↔ ↔ ↔ ↑ ↑ ↑ ↓ ↓ ↓ ↓Soil Infiltration Rate (↑ is higher rate) ↑ ↑ ↑ ↑ ↔ ↔ ↔ ↔ ↓ ↓ ↓Slope (gradient) (↑ is steeper) ↓ ↔ ↓ ↓ ↔ ↔ ↔ ↔ ↓ ↔ ↓ ↓Groundwater depth (↑ is deeper) ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↔ ↑ ↑ ↑ ↑Confined space/safety (↑ is greater required)↑ ↔ ↓ ↓ TBD TBD ↓ ↓ ↓ ↓ ↓ ↔ ↔ ↑ ↓ ↑ ↑Dependency on Soil Characteristics ↓ ↑ ↑ ↔ ↑ ↔ ↔ ↔ ↔ ↑ ↑ ↑
Maintenance level of effort M M+ M+ M TBD TBD L L L L L M M+ H M H+ HFrequency of maintenance M M+ M+ M+ TBD TBD L L L L L M M+ H M H HReliability/durability (appurtenances)M L L L TBD TBD L L L L L L M+ H L H HNeed for "specialized" equipment M L H L TBD TBD L L L L L L M H L H+ HO&M Cost (including waste disposal)H M+ H M TBD TBD L L L L H M+ H H M H+ H
Community Acceptance / / / + + / / / / / + / / / / / /Construction Cost / / - / / - + + + + - - - - / / /Wildlife Habitat / + / / / / / + / +
Best Management PracticePre
treatmentInfiltration Filtration Pool-Ponds Space-constrained or
Urban Application
Maintenance Factors
Non-Design Factors(5)
Physical Site Suitability(4)
Table 4. BMP PerformanceSummary Table*
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BMP SelectionBMPs by Preference
• Infiltration• Media filtration (ecology
embankement, compost filter etc)• Standard sedimentation BMPs with
amended soil
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Infiltration• Infiltration ranks on the top because
it reduces both the volume of runoff and the pollutant load delivered to the receiving waters.
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Infiltration and UICsDEQ now considers UICs to be an
important tool in the stormwater management arsenal.
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UICsUICs must still be registered and
permitted, but DEQ is encouraging system wide permits.
Stormwater must meet Drinking Water Standards before discharge from a UIC
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Low Impact Development1. Anything that can be done to reduce the
volume of stormwater and pollutant load in stormwater
2. Minimization of impervious surface area and direct discharge of stormwater to surface waters
3. Water quality features in the linear right- of-way that emphasis infiltration and filtration through vegetation
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Regulatory Tools: ESA• Programmatic Permits: SLOPES IV
– Treat the Water Quality Design Storm from all the project impervious surface using “highly effective” BMPs
– Maintain pre-project flow and duration for events in the range of the Flow Control Design Storms
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Regulatory Tools: ESAFor individual consultations under the
ESA:• Use BMP Selection Tool to identify
the best and most appropriate treatment technique(s) for the project
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Regulatory Tools: DEQ• ODOT has a Streamlining Agreement
for Stormwater Management Plan approvals– Communication Plan– Performance Standards– SWMP Checklist– Training of ODOT staff
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Stormwater Management Plan Checklist
Stormwater Management Plan Quality Control Checklist Project Description
Project Location o Highway name and number o Milepoint o Township and range
Project elements ADT, current and projected Impervious surface area (total existing and proposed)
Setting
Receiving waters Name(s) and type(s) General description (size, form and character) 5th field HUC Hydrology
Watershed size, Average discharge Alterations to natural hydrology (regulation, irrigation, increased
flashiness) Water resources issues including Pollutants of Concern
TMDL 303(d) Observed Channel condition
ESA/ EFH status Groundwater Management Areas (for infiltration facilities)
o Climate Annual Rainfall Water quality design storm Quantity design storms Other relevant information (snow pack etc.)
o Soils Texture Hydrologic Class
Water Quality Impacts
Existing Pollutant load Proposed Pollutant Load (with treatment) Existing Pollutant concentration Proposed Pollutant concentration (with treatment) Impacts to riparian vegetation
Stormwater Management Existing drainage system
Developed for ODOT projects to assist designers and permit specialists to develop and review Stormwater Management Plans for Section 401 Clean Water Certification.
Regulatory Tools: DEQ
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Regulatory Tools: DEQTraining
• Focused on the development and review of SWMPs
• Is being offered to ODOT staff over the next several months
• Anticipate opening up the training to Consultants and Local Agencies
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Summary• Regulatory scrutiny of stormwater
management and treatment has tightened up considerably
• Use of “Highly Effective” BMPs will ease ESA and DEQ permitting
• So far we have avoided numerical standards
• Guidance on BMPs is available, and the Selection Tool is in development