Stormwater Management for Highway Projects Regulatory Environment And Tools.

Stormwater Management for

Highway Projects

Regulatory EnvironmentAnd

Tools

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

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

Effect determinations

• NMFS is basing Effect Determinations on the quality of the stormwater at the point of discharge

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



NLAA• All stormwater from the Water

Quality Design Storm is infiltrated

No Effect• Non-Pollutant generating surfaces

– Sidewalks– Guardrail flares– Separated bike paths

Action Area

Most 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

Action Area

ODOT has proposed determining the Action Area based on a “defining concentration” resulting from dilution of the highway runoff

FHWA is reviewing the proposal

DEQ 401 Certification

• Heightened scrutiny of projects for 401 certification

• Increased attention to the protection of “Beneficial Uses”


“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


Focus on providing stormwater treatment

“To the Maximum Extent Practicable”

No real definition available: DEQ is being sued over its interpretation

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

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

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

Water Quality Design Storm

Oregon Climate Zones

Water Quality Design Storm

Table 1. Definition of Water Quality Design Storm

Zone Factor (Percentage) x

2-yr, 24-hour rainfall depth at project location

1 50 %

2 50 %

3 50 %

4 67 %

5 75 %

6 50 %

7 50 %

8 50 %

9 67 %

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

Flow Control Design Storm

Lower 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

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

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

BMP Selection

• Key selection criteria (metrics)– Treatment capability– Physical site suitability– Maintenance – Resources, risk and public perception– Cost

Treatment Mechanism – Target Pollutant Matrix

Mechanism

Hyd

rolo

gic

Atte

nu

atio

n

Den

sity

Sep

ara

tion

Sorp

tion

Filtra

tion

Up

take/S

tora

ge

Mic

rob

ial

Tra

nsfo

rmatio

n

Target Pollutan

t

Sediment/Particulate ■ ■ ■

Nutrients ■ ■ ■ ■

Oil and Grease ■ ■ ■ ■ ■

PAHs ■ □ ■ □ ■ ■

Metals (particulate) ■ ■ ■

Metals (dissolved) ■ ■ □ □ □

Oil C

ontrol

Fac

ilitie

s (p

retrea

tmen

t)

Sed

imen

t Con

trol

(pre

trea

tmen

t)

Infiltra

tion

tren

ch/p

ond

Bio

rete

ntion

Bio

slop

e

Por

ous Pav

emen

t (not

sta

nd-a

lone)

Gra

ss S

wal

e (s

oil a

men

ded

)

Filter

Strip

(soi

l am

ended

)

Gra

ss S

wal

e (n

o so

il a

men

dm

ent)

Filter

Strip

(no

soil a

men

dm

ent)

Con

stru

cted

Wet

lands

Ext

ended

Det

ention

Dry

Pon

d

Wet

Pon

ds

Wet

Vau

lts

Med

ia F

ilte

rs (n

on-p

ropriet

ary)

Pro

priet

ary

Sep

arat

ion (p

retrea

tmen

t)

Pro

priet

ary

Filtra

tion

Fac

ilitie

s

Soi

l Am

endm

ents

Cat

ch 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 Practice

Pre

treatment Infiltration Filtration Pool-Ponds

Space-constrained

or Urban

Oil C

ontrol

Fac

ilitie

s (p

retrea

tmen

t)

Sed

imen

t Con

trol

(pre

trea

tmen

t)

Infiltra

tion

Fac

ilitie

s (tre

nch

/pon

d)

Bio

rete

ntion

Bio

slop

e

Por

ous Pav

emen

t (not

sta

nd-a

lone)

Gra

ss S

wal

e (s

oil a

men

ded

)

Filter

Strip

(soi

l am

ended

)

Gra

ss S

wal

e (n

o so

il a

men

dem

ent)

Filter

Strip

(no

soil a

men

dm

ent)

Wet

lands

Ext

ended

Det

ention

Dry

Pon

d

Wet

Pon

ds

Wet

Vau

lts

Med

ia F

ilte

rs (n

on-p

ropriet

ary)

Pro

priet

ary

Sep

arat

ion F

acilitie

s *

Pro

priet

ary

Filtra

tion

Fac

ilitie

s *

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+ H

Frequency of maintenance M M+ M+ M+ TBD TBD L L L L L M M+ H M H H

Reliability/durability (appurtenances)M L L L TBD TBD L L L L L L M+ H L H H

Need for "specialized" equipment M L H L TBD TBD L L L L L L M H L H+ H

O&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 Practice

Pre

treatment

Infiltration Filtration Pool-Ponds Space-constrained or

Urban Application

Maintenance

Factors

Non-Design

Factors(5)

Physical Site

Suitability(4)

Table 4. BMP PerformanceSummary Table*

BMP Selection

BMPs by Preference• Infiltration• Media filtration (ecology

embankement, compost filter etc)• Standard sedimentation BMPs with

amended soil

Infiltration

• Infiltration ranks on the top because it reduces both the volume of runoff and the pollutant load delivered to the receiving waters.

Infiltration and UICs

DEQ now considers UICs to be an important tool in the stormwater

management arsenal.

UICs

UICs must still be registered and permitted, but DEQ is encouraging system wide permits.

Stormwater must meet Drinking Water Standards before discharge from a UIC

Low Impact Development

1. 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

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

Regulatory Tools: ESA

For individual consultations under the ESA:

• Use BMP Selection Tool to identify the best and most appropriate treatment technique(s) for the project

Regulatory Tools: DEQ

• ODOT has a Streamlining Agreement for Stormwater Management Plan approvals– Communication Plan– Performance Standards– SWMP Checklist– Training of ODOT staff

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.



Training• 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

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

Stormwater Management for Highway Projects Regulatory Environment And Tools.

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