Oregon Department of Transportation Stormwater Management Initiative: Meeting New Challenges...

Oregon Department of Transportation Oregon Department of Transportation

Stormwater Management Initiative:Stormwater Management Initiative:Meeting New ChallengesMeeting New Challenges

Presented by:Presented by:Jennifer Sellers, ODOTJennifer Sellers, ODOT

andandRonan Igloria, HDRRonan Igloria, HDR

ACWA Stormwater Committee MeetingACWA Stormwater Committee MeetingNovember 27, 2007November 27, 2007

ODOT’s GoalsODOT’s Goals Develop a streamlined stormwater Develop a streamlined stormwater

treatment program to: treatment program to: Meet all regulatory needsMeet all regulatory needs

Provide ODOT with certainty Provide ODOT with certainty regarding scope, schedule, and regarding scope, schedule, and budget budget

Result in an overall environmental Result in an overall environmental benefit and promote species benefit and promote species recoveryrecovery

Components of the Stormwater Components of the Stormwater Initiative Work PlanInitiative Work Plan

Streamline DEQ Stormwater Streamline DEQ Stormwater Management Plan Approval Management Plan Approval ProcessProcess

Develop Process for ODOT Develop Process for ODOT Projects with T&E Species Projects with T&E Species and Stormwater Effectsand Stormwater Effects

Develop a watershed-based Develop a watershed-based mitigation program to offset mitigation program to offset stormwater effects that stormwater effects that cannot be treated “on-site” cannot be treated “on-site” with reasonable effortswith reasonable efforts

Develop Process for ODOT Projects with Develop Process for ODOT Projects with Stormwater EffectsStormwater Effects

Problem StatementProblem Statement

Stormwater has become a major impediment to Stormwater has become a major impediment to efficient ESA consultation process due to:efficient ESA consultation process due to:

Lack of congruence in water quality requirements Lack of congruence in water quality requirements between DEQ and NMFSbetween DEQ and NMFS

Changing thresholds for effects determinations in Changing thresholds for effects determinations in ESA Section 7 consultations ESA Section 7 consultations

Changing science regarding the action area for Changing science regarding the action area for dissolved metals (e.g. copper)dissolved metals (e.g. copper)

Lack of early coordination to identify emerging Lack of early coordination to identify emerging issues (i.e., new pollutants of concern)issues (i.e., new pollutants of concern)

Proposed Strategy/ProcessProposed Strategy/Process

Compile and synthesize literature Compile and synthesize literature on BMPs for stormwater treatmenton BMPs for stormwater treatment

Define water quality design stormDefine water quality design storm

Develop water quantity guidanceDevelop water quantity guidance

Develop Process for ODOT Projects with Develop Process for ODOT Projects with Stormwater EffectsStormwater Effects

Develop Strategy/Process for ODOT Develop Strategy/Process for ODOT Projects with Stormwater EffectsProjects with Stormwater Effects

Proposed Strategy/Process (cont.)Proposed Strategy/Process (cont.)

Incorporate minimization of stormwater impacts Incorporate minimization of stormwater impacts into project design (Low Impact Development into project design (Low Impact Development techniques)techniques)

Select most appropriate stormwater treatment Select most appropriate stormwater treatment BMPs for each project BMPs for each project

Develop a BMP Selection Tool and User’s GuideDevelop a BMP Selection Tool and User’s Guide

Proposed Strategy/Process (cont.)Proposed Strategy/Process (cont.)

Developing ESA Effects Determination GuidanceDeveloping ESA Effects Determination Guidance

Exploring expanding SLOPES IV and/or ESA Exploring expanding SLOPES IV and/or ESA programmatic consultation programmatic consultation

Will develop a performance measurement and Will develop a performance measurement and reporting methodreporting method



Anticipated Benefits for Anticipated Benefits for Regulatory AgenciesRegulatory Agencies

Meet regulatory requirementsMeet regulatory requirements

Well-defined terms and conditions that allow Well-defined terms and conditions that allow for flexibility in applicationfor flexibility in application

Protect ESA-listed fishProtect ESA-listed fish

Protect Oregon’s water quality and wetland Protect Oregon’s water quality and wetland resourcesresources


Anticipated Benefits for ODOTAnticipated Benefits for ODOT

Certainty in project development and constructionCertainty in project development and construction

Reduction in project delaysReduction in project delays

Support ODOT’s sustainability goalsSupport ODOT’s sustainability goals


Where are we now?Where are we now?

BMP Summary Reports BMP Summary Reports CompletedCompleted

BMP Selection Tool in BMP Selection Tool in developmentdevelopment

BMP Selection Tool Users’ BMP Selection Tool Users’ Guide to be developedGuide to be developed


Where are we now (cont.)Where are we now (cont.) Draft Water Quality Design Storms near Draft Water Quality Design Storms near

completioncompletion Water Quantity Guidance near completionWater Quantity Guidance near completion ESA Effects Determination Guidance for Water ESA Effects Determination Guidance for Water

Quality near completionQuality near completion

Design Storm EvaluationDesign Storm Evaluation

Water QualityWater Quality (and Water Quantity) (and Water Quantity)

Science-basedScience-based

– Geography-specific (hydrologic zones)Geography-specific (hydrologic zones)

Economics (cost-benefit)Economics (cost-benefit)

– Effects on facility sizeEffects on facility size

Ultimately a “Policy” decisionUltimately a “Policy” decision

Water Quality Design StormWater Quality Design Storm

Based on analysis of rainfall data from >50 Based on analysis of rainfall data from >50 precipitation stations across the state’s nine precipitation stations across the state’s nine climate zonesclimate zones

– Cumulative percent of total rainfall vs. storm Cumulative percent of total rainfall vs. storm sizesize

– Percentile of storm size Percentile of storm size

– Percent rainfall treatedPercent rainfall treated

– ““Sensitivity Analysis” for sizing treatment Sensitivity Analysis” for sizing treatment facilitiesfacilities


Oregon Climate Zones


Cumulative Percent of Rainfall by Storm Size

Water Quality Design Storm Analysis

0%

20%

40%

60%

80%

100%

0 0.5 1 1.5 2 2.5 3 3.5 4

Storm Size (depth, in.)

Per

cen

t o

f T

ota

l Rai

nfa

ll

Astoria Portland Corvallis Medfiord Pendleton Bend (View in Color)

Pendleton

Bend Astoria

Corvallis

Portland

Medford


Portland - Station 356751Percent Rainfall Volume Treated for Different Design Storm

85%

90%

95%

100%

105%

0 0.5 1 1.5 2 2.5 3 3.5

Storm depth, in

Per

cen

t T

rea

ted

% Treated (70% storm) % Treated (75% storm) % Treated (80% storm)

% Treated (85% storm) % Treated (90% storm) % Treated (95% storm)

70% Storm

75% Storm

80% Storm

85% Storm

90% Storm

95% Storm


Facility Size Sensitivity to Design StormGrassy Swale

0.00%

50.00%

100.00%

150.00%

200.00%

250.00%

70% 75% 80% 85% 90% 95%

Design Storm

Cu

mu

lati

ve

Pe

rce

nt

Inc

rea

se

in

To

p W

idth

Ashland

Astoria

Bend

Corvallis

Detroit Dam

La Grande

Medford

Newport

Pendleton

Portland

Sheaville

Silver Lake


ANOVA Analysis was used to group similar climate ANOVA Analysis was used to group similar climate zoneszones

Design storm corresponding to 85% cumulative Design storm corresponding to 85% cumulative rainfall results in:rainfall results in:

– >95% of rainfall treated>95% of rainfall treated

– >97>97thth percentile storm size percentile storm size

Facility size is most “sensitive” to design storms Facility size is most “sensitive” to design storms when increasing from 90% to 95% cumulative when increasing from 90% to 95% cumulative rainfall design stormrainfall design storm


Use the mean storm size corresponding to 85% Use the mean storm size corresponding to 85% cumulative rainfall for each station in the climate cumulative rainfall for each station in the climate zones.zones.

Define a water quality design storm for 5 zonesDefine a water quality design storm for 5 zones

ZoneZone Current Current DefinitionDefinition

85% Cumulative 85% Cumulative RainfallRainfall

11 1.61.6 2.32.3

2 and 32 and 3 1.01.0 1.41.4

44 1.51.5 2.32.3

55 0.60.6 1.31.3

6,7,8, and 96,7,8, and 9 0.50.5 0.70.7

BMP SelectionBMP Selection

Best Available TechnologyBest Available Technology– BMPs included in ODOT Hydraulics ManualBMPs included in ODOT Hydraulics Manual– Emerging and LID-type BMPs (e.g. bioslope, Emerging and LID-type BMPs (e.g. bioslope,

soil amendments)soil amendments) Key selection criteria (metrics)Key selection criteria (metrics)

– Treatment suitabilityTreatment suitability– Physical site suitabilityPhysical site suitability– MaintenanceMaintenance– CostCost– Resources, risk and public perceptionResources, risk and public perception


Conceptual Stormwater Treatment Design Conceptual Stormwater Treatment Design StrategyStrategy– SW Strategy SW Strategy Figure.pdfFigure.pdf

Schematic of BMP Selection ToolSchematic of BMP Selection Tool– Selection Tool Selection Tool Schematic.pdfSchematic.pdf


Treatment SuitabilityTreatment Suitability High variability with “effectiveness” dataHigh variability with “effectiveness” data Based on treatment mechanismsBased on treatment mechanisms

– Hydrologic attenuationHydrologic attenuation– Sedimentation/density separationSedimentation/density separation– SorptionSorption– FiltrationFiltration– Uptake/storageUptake/storage– Microbially-mediated transformationMicrobially-mediated transformation


Hydr

olog

ic At

tenu

atio

n (1

)

Dens

ity S

epar

atio

n

Sorp

tion

(che

mica

l act

ivity

)

Filtr

atio

n

Upta

ke/S

tora

ge(2

)

Micr

obia

l Tra

nsfo

rmat

ion(3

)

Sediment/Particulate (suspended solids) ■ ■ ■Nutrients(4) ■ ■ ■ ■Oil and Grease ■ ■ ■ ■ ■Polycyclic Aromatic Hydrocarbons (PAH) ■ ■ ■ ■Metals (particulate) ■ ■ ■Metals (dissolved) ■ □ □ ■ ■

□ = Depending on chemical activity of filter media(1) Refers to infiltration which is credited for overall pollutant mass load reduction of all

target pollutants primarily through volume reduction; pollutant removal is

also achived through filtering, sorption, and microbial transformation in the soil column.(2) Dependent on plant species(3) Dependent on types of microbes present (in soil or water column)(4) May not be considered a highway target pollutant, but included for completeness

Table 2. Treatment Mechanism - Target Pollutant Matrix

Targ

et P

ollu

tant

Mechanism


Oil C

ontro

l Fac

ilitie

s (p

retre

atm

ent)

Sedi

men

t Con

trol (

pret

reat

men

t)

Infilt

ratio

n tre

nch/

pond

Bior

eten

tion

Bios

lope

Poro

us P

avem

ent (

not s

tand

-alo

ne)

Gra

ss S

wale

(soi

l am

ende

d)

Filte

r Stri

p (s

oil a

men

ded)

Cons

truct

ed W

etla

nds

Exte

nded

Det

entio

n Dr

y Po

nd

Wet

Pon

ds

Wet

Vau

lts

Med

ia F

ilters

(non

-pro

prie

tary

)

Prop

rieta

ry S

epar

atio

n (p

retre

atm

ent)

Prop

rieta

ry F

iltrat

ion

Facil

ities

Hydrologic Attenuation ■ ■ ■ ■ □ □ □ ■ □Density Separation (Sedimentation/Flotation) ■ ■ □ ■ □ □ □ ■ ■ ■ ■ ■Sorption □ □ ■ ■ ■ ■ ■ □ □ □ □ □ ■Filtration □ □ ■ ■ ■ ■ ■ ■ □ □ □ ■ □ ■Uptake/Storage(1)

□ ■ □ □ □ ■ □ □Microbial Transformation(1)

□ ■ □ □ □ ■ □ □ □ □

Sediment/Particulate (suspended solids) ○ ● ● ● ● ● ● ● ● ● ● ● ● ● ●Nutrients ● ● ● ● ○ ○ ● ○ ○ -Oil and Grease ● ○ ● ● ● ● ● ● ● ○ ○ ○ ● ● ●Polycyclic Aromatic Hydrocarbons (PAH) ● ● ● ● - - ● ○ ○ -Metals (particulate) ○ ○ ● ● ● ● ● ● ● ● ● ● ● ● ●Metals (dissolved) ● ● ● ● ○ ○ ● ○ ○ ○ ○

■ = Key treatment mechanism for BMP

□ = Associated treatment mechanism for BMP; dependent on plant species/microbes present

● = High capability to remove target pollutant

○ = Moderate capability to remove target pollutant

- = Low capability to remove target pollutant(1) Dependent on types of plant species or microbes (in soil or water column) present

Targ

et P

ollu

tant

Table 3. Treatment Mechanism - BMP Matrix

Trea

tmen

t Mec

hani

smBest Management Practice

Pretreatment Infiltration Filtration Pool-Ponds

Space-constrained or Urban Application


Priority BMPs for Treating Dissolved MetalsPriority BMPs for Treating Dissolved Metals

Treatment MechanismsTreatment Mechanisms

– Hydrologic Attenuation (infiltration) – preferredHydrologic Attenuation (infiltration) – preferred

– Sorption, uptake, microbial transformationSorption, uptake, microbial transformation

““Preferred” BMPsPreferred” BMPs

– Infiltration trenchInfiltration trench

– BioretentionBioretention

– Bioslope (“Ecology Embankment”)Bioslope (“Ecology Embankment”)

– Amended Swale and Filter StripAmended Swale and Filter Strip


Next StepsNext Steps Finalize Metric RatingsFinalize Metric Ratings Apply to Pilot ProjectsApply to Pilot Projects Integrate into an “Electronic Tool”Integrate into an “Electronic Tool” Develop Users’ GuideDevelop Users’ Guide

Questions?Questions?

Water Quantity Design StormWater Quantity Design Storm

Match pre-project hydrology from a low-Match pre-project hydrology from a low-discharge, high frequency event to a high-discharge, high frequency event to a high-discharge, low-frequency eventdischarge, low-frequency event

Low discharge eventLow discharge event: when substantial bed-: when substantial bed-load begins to occurload begins to occur

High discharge eventHigh discharge event: bank over-topping : bank over-topping event; or when amount of impervious area has event; or when amount of impervious area has little effect on stream discharge (10-year/24-hour little effect on stream discharge (10-year/24-hour event)event)


Low discharge eventLow discharge event: when substantial bed-: when substantial bed-load begins to occur; Studies have shown:load begins to occur; Studies have shown:

– 2/3 of bankfull discharge 2/3 of bankfull discharge

– 50% of 2-year/24-hour event50% of 2-year/24-hour event

Average bankfull discharge event:Average bankfull discharge event:

– Eastern OR = 1.5-year/24 hour eventEastern OR = 1.5-year/24 hour event

– Western OR = 1.2-year/24 hour eventWestern OR = 1.2-year/24 hour event

64 streamflow gauges were analyzed from 8 flood 64 streamflow gauges were analyzed from 8 flood frequency regions defined by USGSfrequency regions defined by USGS


Low Discharge End PointLow Discharge End Point::

– West Region: 42% of 2-year,24 hour eventWest Region: 42% of 2-year,24 hour event

– SE, NE, NC Regions: 48% of 2-year, 24-hour SE, NE, NC Regions: 48% of 2-year, 24-hour eventevent

– E-Cascades: 56% of 2-year, 24 hour eventE-Cascades: 56% of 2-year, 24 hour event

High Discharge End Point:High Discharge End Point:

– 10-year, 24-hour event for incised streams; or10-year, 24-hour event for incised streams; or

– Event corresponding to bank overtopping Event corresponding to bank overtopping recurrence interval for minimally incised recurrence interval for minimally incised streamsstreams


Design CriteriaDesign Criteria::

– Minimum ¼ acre or 0.5 cfs increase in Minimum ¼ acre or 0.5 cfs increase in discharge from project sitedischarge from project site

– Considerations for Minimum orifice sizeConsiderations for Minimum orifice size

Oregon Department of Transportation Stormwater Management Initiative: Meeting New Challenges...

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