Stormwater in the FAHP. Stormwater Management Goals Treat the runoff generated from the Contributing Impervious Area by the Water Quality Design Storm

Stormwater in the Stormwater in the FAHPFAHP

Stormwater in the FAHP

Stormwater Management Stormwater Management GoalsGoals

Treat the runoff generated from the Treat the runoff generated from the Contributing Impervious Area by the Contributing Impervious Area by the Water Quality Design Storm using Water Quality Design Storm using “Preferred” BMPs“Preferred” BMPs

Maintain the frequency and duration of Maintain the frequency and duration of the most important channel forming flowsthe most important channel forming flows

Triggers for Stormwater Triggers for Stormwater ManagementManagement

What Triggers Stormwater What Triggers Stormwater TreatmentTreatment

Construct new pavement that Construct new pavement that increases capacity or widens the increases capacity or widens the

road prism:road prism:

Add a lane, a turn refuge, a wider Add a lane, a turn refuge, a wider paved shoulderpaved shoulder

Build a new alignmentBuild a new alignment


Increase the CIAIncrease the CIA

Adding new pavement, orAdding new pavement, or

Change the drainage to capture Change the drainage to capture stormwater from outside the pre-stormwater from outside the pre-

project CISproject CIS


Change the Stormwater Change the Stormwater Conveyance:Conveyance:

Relocate the drainage Relocate the drainage systemsystem

Change the type of Change the type of conveyance:conveyance:• Replace a ditch with a Replace a ditch with a

pipepipe• Add curbing, etc. Add curbing, etc.

Enlarge the capacity of Enlarge the capacity of the conveyancethe conveyance


Reconstruct pavement down to Reconstruct pavement down to subgradesubgrade

This applies to projects rehabilitating a This applies to projects rehabilitating a highway, not localized repairs.highway, not localized repairs.


Replace a Stream CrossingReplace a Stream Crossing


Major Structural Repairs of Major Structural Repairs of BridgesBridges

This is the stuff that is not normal This is the stuff that is not normal maintenancemaintenance

Exempted are Seismic Upgrades that Exempted are Seismic Upgrades that do not affect the deck or drainagedo not affect the deck or drainage

What Is Not a TriggerWhat Is Not a Trigger

Explicit:Explicit:

Minor repairsMinor repairs Repaving and resurfacing that does Repaving and resurfacing that does

not go down to the subgradenot go down to the subgrade

What Is Not a TriggerWhat Is Not a Trigger

ImplicitImplicit Minor, localized increases in Minor, localized increases in

impervious surface, such as:impervious surface, such as:• Guardrail flaresGuardrail flares• Police, bus, and mail-box pulloutsPolice, bus, and mail-box pullouts

Sidewalks and separated bike/ped Sidewalks and separated bike/ped paths that do not include installation paths that do not include installation of curbingof curbing

The Thing About SidewalksThe Thing About Sidewalks

It’s not the sidewalk, it is the curbIt’s not the sidewalk, it is the curb By putting in a curb the drainage is By putting in a curb the drainage is

changed, and highway runoff that changed, and highway runoff that may have gotten some incidental may have gotten some incidental treatment now gets none.treatment now gets none.

Flow Control TriggerFlow Control Trigger

Discharge into a receiving water with Discharge into a receiving water with an upstream drainage basin of less an upstream drainage basin of less than 100 mi2, and increase the peak than 100 mi2, and increase the peak 10 year/24 hour discharge by 0.5 cfs 10 year/24 hour discharge by 0.5 cfs or more*.or more*.

Water Quality Design StormWater Quality Design StormSite Specific Storm Size from ODOT Precipitation

Viewer

50%

67%75%

Percentage of the 2 year 24 hour storm:

Min: 0.7 inches

Max: 2.5 inches

Contributing Impervious Contributing Impervious Area:Area:

Pavement, new and old, within the Pavement, new and old, within the project limits, andproject limits, and

Highway related pavement that Highway related pavement that drains into the projectdrains into the project

CIA Boundaries

Project Limits

CIA if stormwater

treatment within project

limits CIA if stormwatertreatment at the bottom of the hill

Project Limits

The stormwater that gets treated The stormwater that gets treated comes from comes from • The projectThe project• Adjacent highway that drains onto Adjacent highway that drains onto

project pavementproject pavement• Highway that discharges into a Highway that discharges into a

drainage system that is modified by the drainage system that is modified by the project, or is in the conveyance when it project, or is in the conveyance when it discharges into the treatment facilitydischarges into the treatment facility

Always?Always?

If the CIA outside of the project limits is If the CIA outside of the project limits is very large compared to the project, very large compared to the project,

coordinate and negotiate with NMFS.coordinate and negotiate with NMFS.

EarlyEarly

The intention of the FAHP is not to The intention of the FAHP is not to derail projects by placing onerous derail projects by placing onerous

requirements on projects.requirements on projects.

Contributing Impervious Contributing Impervious Area:Area:

FAHP explicitly limits the CIA to the FAHP explicitly limits the CIA to the highway and highway associated highway and highway associated facilities. Run-on from adjacent facilities. Run-on from adjacent properties is not part of the CIA.properties is not part of the CIA.

BMPsBMPs

Infiltration:

•Infiltration Basins•UICs•Filter Strips with no adjacent conveyance or receiving water

Surface Treatment

•Bioswale•Bioretention (with underdrain)•Bioslope (Ecology Embankment)•Filter strip•Detention/Retention Pond•Constructed Wetland•Proprietary Filter System (on QPL)

BMPsBMPs

Use BMPs that are highly effective Use BMPs that are highly effective at treating the broad range of at treating the broad range of highway pollutants, i.e. those that highway pollutants, i.e. those that incorporate a high degree of incorporate a high degree of filtration through soil or media.filtration through soil or media.

ODOT’s Hydraulic Manual includes ODOT’s Hydraulic Manual includes the BMP Selection Tool to help the BMP Selection Tool to help identify and choose the preferred identify and choose the preferred BMPsBMPs

Stormwater Management Stormwater Management StragetyStragety

1.1. Unmodified roadside ROWUnmodified roadside ROW

2.2. Modified (enhanced) roadside ROWModified (enhanced) roadside ROW

3.3. Small, dispersed BMPsSmall, dispersed BMPs

4.4. Large, consolidated BMPsLarge, consolidated BMPs

5.5. Do the best possible,Do the best possible,

6.6. And if all else fails, Off-site And if all else fails, Off-site mitigationmitigation

Off-site Mitigation: Off-site Mitigation: JustificationJustification

Unfavorable topographyUnfavorable topography Site hazards (geologic, haz-mat, Site hazards (geologic, haz-mat,

safety etc.)safety etc.) Conflicting resources (Wetlands, T&E, Conflicting resources (Wetlands, T&E,

Historic, Archeologic, Env. Justice Historic, Archeologic, Env. Justice etc.)etc.)

Excessive cost to benefit (ROW, Excessive cost to benefit (ROW, Maintenance/Life Cycle, Maintenance/Life Cycle, Construction)Construction)

Off-Site MitigationOff-Site Mitigation

MUST coordinate with MUST coordinate with NMFS!!!NMFS!!!

Aim for a site with Aim for a site with The same general ADT, The same general ADT, The same impervious surface area, The same impervious surface area,

and and The same watershed.The same watershed.

Flow Control Range of Flows:Flow Control Range of Flows:Lower endLower end

Eastern Cascade = 56% of the 2-year Eastern Cascade = 56% of the 2-year SE, NE, N Central Oregon = 48% of the 2-SE, NE, N Central Oregon = 48% of the 2-

yearyear Western Oregon: 42% of the 2 year Western Oregon: 42% of the 2 year

Upper EndUpper End Bank overtopping if ER is = or > 2.2Bank overtopping if ER is = or > 2.2 10 year 24 hr storm if ER is < 2.210 year 24 hr storm if ER is < 2.2

Approval of SWMPsApproval of SWMPs

Required for Flow Control for projects Required for Flow Control for projects discharging to watersheds smaller than discharging to watersheds smaller than

100 mi100 mi22, or, or

Projects that do not meet the SW design Projects that do not meet the SW design standards on-site.standards on-site.

NotificationNotification


Impervious surface, both project and Impervious surface, both project and total CIA, with net changetotal CIA, with net change

Acres treated on and off site, by Acres treated on and off site, by infiltration and surface BMPsinfiltration and surface BMPs


Traffic Volumes for the project area Traffic Volumes for the project area and any off-site mitigation locationand any off-site mitigation location

General Categories:General Categories:Very High: >100,000 ADTVery High: >100,000 ADTHigh: 30,000-100,000High: 30,000-100,000Medium: 10,000-30,000Medium: 10,000-30,000Low: 2,000-10,000Low: 2,000-10,000Very Low: <2,000Very Low: <2,000


Water Quality and Flow Control Water Quality and Flow Control Design Storm depthsDesign Storm depths

Reason for exemption from flow Reason for exemption from flow control (if applicable)control (if applicable)

Stormwater Manual used for designStormwater Manual used for design


List of BMPs usedList of BMPs used• Drainage Area (AKA Sub-basin)Drainage Area (AKA Sub-basin)• Treatment Method (category): on or off Treatment Method (category): on or off

site, surface discharge or infiltrationsite, surface discharge or infiltration• BMP typeBMP type• Impervious surface area treatedImpervious surface area treated• Receiving WaterReceiving Water


Site plan with Site plan with CIA, sub-basins, CIA, sub-basins, flow path, BMP flow path, BMP locations and locations and receiving watersreceiving waters

Tracking/MonitoringTracking/Monitoring

BMPs Installed, Inspected and BMPs Installed, Inspected and MaintainedMaintained

Any Stormwater Recommendation or Any Stormwater Recommendation or Design reports developed and Design reports developed and stamped by an engineerstamped by an engineer

O&M ManualO&M Manual

Tracking/MonitoringTracking/Monitoring

Photo of the outfalls from a projectPhoto of the outfalls from a project Map of the project with outfalls and Map of the project with outfalls and

receiving watersreceiving waters

Other StuffOther Stuff

If the highway runoff discharges to a If the highway runoff discharges to a CSO:CSO:

Documentation that the facility will Documentation that the facility will accept the runoff and has adequate accept the runoff and has adequate capacitycapacity

Description of how the runoff will be Description of how the runoff will be treated to a level comparable to the treated to a level comparable to the BMPs listed in the FAHP.BMPs listed in the FAHP.

Advance MitigationAdvance Mitigation No formal process yet.No formal process yet. NMFS does not have a mechanism NMFS does not have a mechanism

outside of a BO to designate outside of a BO to designate treatment at one location as treatment at one location as mitigation for a future project, and mitigation for a future project, and even that is uncertain.even that is uncertain.

““Excess Treatment”Excess Treatment”

No formal definition…No formal definition… Deliberately taking stormwater from Deliberately taking stormwater from

outside of a project’s CIA in order to outside of a project’s CIA in order to treat it in a project’s BMPtreat it in a project’s BMP

Specify a project or an area that may Specify a project or an area that may need the off-site mitigationneed the off-site mitigation

Discuss this with NMFS in Discuss this with NMFS in advance!advance!

Documents

Stormwater in the FAHP. Stormwater Management Goals Treat the runoff generated from the Contributing Impervious Area by the Water Quality Design Storm