EPA Stormwater Rules Stormwater Infiltration and Drinking Water Sources

EPA New EnglandDrinking Water Source ProtectionTed Lavery(617) 918-1683Lavery.ted@epa.gov

Ipswich, MA – Wellhead Protection Area

Stormwater Needs to be a Source of Recharge But Can also be a cause of water quality impairment to ground water• Urbanization results in new sources of ground water recharge:

- Domestic septic systems- Residential Irrigation- Additional Impervious Area -Road/Parking Lot Runoff- Industrial Waste Injection Wells

• These new urban sources contribute metals, petroleum hydrocarbons, pesticides, TSS and nutrients if left untreated.

• “Infiltration devices can safely deliver large fractions of the surface flows to groundwater, if carefully designed and located.”

• Improper locations of Infiltration Systems near hot-risk areas, such as service stations can lead to contamination (Source: Dr. Robert Pitt – U. of Alabama at Birmingham)

Urbanized areas in the U.S.

About 6,000 Phase II MS4s Urbanized areas cover 2% of total U.S. land area

Categories of Stormwater BMPs

Infiltration Practices• Infiltration Trenches and Basins

Filtering Practices• Proprietary Media Filters• Sand & Organic Filters• Bioretention Areas/Rain Gardens

Constructed Stormwater Wetlands• Gravel, Basin & Pocket Wetlands• Dry Detention Basins• Subsurface Structures

Pretreatment Devices• Deep Sump & Leaching Catch Basins• Oil & Grit Separators• Check Dam/Stone Weir• Proprietary Separators• Vegetated Filter Strips • Dry Wells

MA Design Requirements - Stormwater Infiltration BMPs BMP Wellhead

Protection Area (Zone II) Setback

Surface Water (Zone A & Within 200ft)

Surface Water B Setback:

All Infiltration BMPs

Infiltration Trenches:Recommended outside of Zone I

Restricted to small drainage areas (<5 acres).

Infiltration Basins: Designed to treat 15 acres of less

Source: MA Stormwater Manual

Min. of 80% TSS removal prior to discharge.

Highly recommendedwith pretreatment to prevent clogging

Must avoid creatingmounding near Chapter21E sites.

Oil & grit separator or sand filter required 2 ft separation fromgroundwater required

Minimum of 80% TSS removal prior to discharge.

Recommended outside of Zone A (Surface Water Protection Area) .

Minimum of 80% TSS removal prior to discharge.

Highly recommendedwith pretreatment to prevent clogging

Must avoid creatingmounding near Chapter21E sites.

Oil & grit separator orSand filter required 2 ft separation fromgroundwater required

NH State Requirements for Stormwater Infiltration Systems

Wellhead Protection Area Setback: Surface Water Intake Area Setback:

Minimum 75–400 ft set-back between any stormwater treatment practice and public drinking water well depending on well production.

Allowed in ground water protection area if stormwater from high-load area provided system has source control plan.

Infiltration prohibited in areas if stormwater comes from areas with USTs or have contaminants in GW above ambient GW standards or soil standards.

Infiltration must have 4 ft of vertical separation from Seasonal High Water Table.

No discharge from dry wells to public water area within 1,000 ft. of a public wellhead protectionAreaSource: NH Alteration of Terrain Manual

Discharge setback of 100 ftwithin water supply intake protections areas as specifiedunder EnvWq 1508(b).

Infiltration must have 4 ft of vertical separation from Seasonal High Water Table

Filtering practices must have 1 ft vertical separation.

Stormwater Restrictions Near Drinking Water Supplies in New EnglandConnecticut: CT’s Aquifer Protection Regulations • Prohibits most industrial activities from installing dry wells or other infiltration

devices.

Maine: Stormwater Rules• Prohibit infiltration galleries or dry well recharge from stormwater within the

delineated contributing area of a public supply well.

Rhode Island: 1. Infiltration facilities shall be located at least 400 feet horizontally from any

public drinking water supply well.

2. Residential dry wells and infiltration facilities for private driveways shall be located at least 25 feet horizontally from all private drinking water wells.

3. All other infiltration facilities shall be located at least 200 feet horizontallyfrom all surface water supplies and tributaries.

Vermont: Stormwater runoff from designated hot spot land uses or activities must not be directed to infiltration facilities or dry wells.

Stormwater Best Management Practices that Qualify as Class 5 Underground Injection Wells

Stormwater BMP Pretreatment Device -Qualifies as a stormwater drainage well?

Is this BMP a Class 5 UIC Well? (Registration & Licensing Required)

Dry Detention Basins Yes -If subsurface structure and meet the definition of a well (Deeper than Wide)

Deep Sump Catch Basins Yes -If subsurface structure and meet the definition of a well (Deeper than Wide)

Oil & & Grit Separators Yes – If Discharge Structure

Sand & Organic FiltersYes – If Discharge Structure

Proprietary Media FiltersYes – If Discharge Structure

Proprietary SeparatorsYes – If Discharge Structure

Stormwater BMPs that Qualify as Underground Injection Wells (Class 5)Stormwater BMP Pretreatment Device -

Qualifies as a stormwater drainage well?

Is this BMP a Class 5 UIC Well? (Registration & Licensing Required)

Leaching Catch BasinsYes

Subsurface Structures Yes

Dry Wells Yes

Infiltration Trenches and Basins

Yes - If subsurface structure installed and meets the definition of a well (Deeper than Wide)

Vegetated Filter StripsBioretention Cells

Yes, If subsurface structure installed and meets the definition of a well. (Deeper than Wide)

Constructed Stormwater Wetlands

Yes -If subsurface structure and meet the definition of a well (Deeper than Wide)

Stormwater Infiltration Performance Analysis - Massachusetts

Stormwater Infiltration

BMPs

Pathogen Removal

TSS Removal Metals Removal (Cu, Pb, Zn, Cd)

Nutrient Removal (N/P)

Site ConsiderationsNear Source

Waters Infiltration Trenches

Up to 90% 80% with pretreatment

85-90% 40-70% Nitrogen

60-70% Phosp.

Recommended outside of Zone I (Wellhead Protection Area or Zone A (Surface Water Protection Area.Restricted to small drainage areas (<5 acres).

Infiltration Basins Up to 90% 80% with pretreatment

85-90% 50-60% Nitrogen

60-70% Phosp.

Highly recommended with pretreatment to remove oil & grease.Recommended for contributing areas of 15 acres or less.

Proprietary Media Filters

Performance varies with specific unit selected, the targeted pollutants

Variable Variable Variable Pretreatment device only.

Media Filters must be sized to target land use loadings and storm event.

Sand & Organic Filters

Not rated 80% TSS removal with pretreatment

50-90% 20-40% Nitrogen Removal

10-50% Phosp. Removal

Restricted to small drainage areas (1-10 acres).

Bioretention Areas & Raingardens

Not rated 90% with adequate pretreatment (vegetated filter strip or equivalent)

40-90% 30%-50%Nitrogen Removal

30-90% Phosp. Removal

Pretreatment required for infiltration practices for runoff from land uses with high concentrations of oil and grease.

BMP Performance Analysis - MassachusettsStormwater Infiltration

BMPs

Pathogen Removal

TSS Removal Metals Removal (Cu, Pb, Zn, Cd)

Nutrient Removal (N/P)

Site ConsiderationsNear Source

Waters Dry Wells- Not rated 80% Not rated Not rated Allowed only to treat

roof runoff from non-metal roofs within wellhead protection areas. May not be used near parking lot areas.

Deep Sump Catch Basins

Not rated Not rated Not rated Not rated Pretreatment device only that provide additional TSS removal.

Leaching Catch Basins

Not rated 80% if combined with deep sump catch basin

Not rated Not rated Pretreatment device only that provide additional TSS removal.

Subsurface Structures

Not rated 80% TSS removal with pretreatment

Not rated Not rated Pretreatment device only. Required for areas with high potential for pollutant loadings

Constructed Stormwater Wetlands

Up to 75% 80% TSS removal with pretreatment

20-85% Total N – 20-55%Total P – 40-60%

Recommended for source water protection areas. Effective at nutrient removal.

Infiltration Trenches

Restrictions Provides high levels of pollutant removals (including pathogens and metals)

• Restrictions – Best suited for small contributing areas

• Not usually allowedin WHPAs but allowed in surface water areas outside intake zone or stream buffer zonesSebago Lake: Standish, Maine, Unfiltered Drinking Water Supply for Portland, ME

Infiltration Basin-Restrictions & Performance

• Provides high levels of pollutant removals:

Including pathogens ~90%), metals (Cu, Pb, Zn, Cd 85-90%) and nutrients (Total Nitrogen –50-60%, Total Phosphorous- 60-70%)

• Effective at treating stormwater from large contributing areas (up to 15 acres)

• Requires Pretreatment

Disadvantage: • Requires significant amount of

land

Wet Ponds or Wet Basins Restrictions & Performance

• Effectively treats total suspended solids, metals and nutrients but nutrients may be stored

• Sediment Forebay-Usually included• Depth 3-6 feet• Algae and vegetation remove

soluble pollutants• Long detention times allow for

settling of fine sediments.• Effective at treating stormwater

from large contributing areas(up to 15 acres)

• Treatment performance usually declines

• Cost: $13K/impervious acre

Maine DOT Detention basin near I-95 Wells, Maine- Includes spill control structure to river (surface water source for Kennebunk, Kennebunkport and Wells, Maine)

Subsurface Gravel WetlandWetlands

-Restrictions & PerformanceHighly recommended for source waters due to pollutant removal capabilities.

• Provides a high level of pollutant removal (70-95% TSS removal with pretreatment)

• Consists of 2 basins, each lined with up to 2 ft of gravel

• Filters 100% of volume received for small storms

• Can be used for retrofits such as dry ponds or large detention basins

• Lowers runoff temperatures

Disadvantages:• High cost per impervious area

treated (>$22K / acre impervious area)

U. Of New Hampshire Stormwater Center: www.unh.org/erg/cstev

Biofilters or Rain GardensRestrictions & Performance

High degree of TSS, metals and petroleum hydrocarbon removal

• Filter media mix must be free of phosphorous and clay. Check soil media mixes.

• Good for small sites - Small Footprint: Requires 5-7% of impervious area treated

• Can be used for parking lots and retrofit situations

• Cost: $18K / acre of impervious cover Site located in South Burlington,

Vermont: Intercepts stormwater runoff near Lake Champlain (Public Water Supply for Burlington, VT)

State BMP Rating/Performance Mass & NH

0102030405060708090

100

Infil T

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Infil T

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Infilt.

Bas

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A

Infilt.

Bas

ins-N

H

Media

Filters-

MA

Media

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NH

Sand &

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nic F

ilters-

MA

Sand &

Orga

nic F

ilters-

NH

Biorete

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as &

Rain

gard

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A

Biorete

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as &

Rain

gard

ens-N

H

Constr

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Stor

mwater W

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A

Constr

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Stor

mwater W

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TSS % RemovalNitrogen % RemovalPhosp. % Removal

Stormwater Infiltration Conclusions Pretreatment is essential for stormwater controls to reduce pollutants (viruses, nitrogen, pesticides, metals, salts, and organic compounds).

-Locating these structures outside of wellhead protection areas and drinking water surface intake zones is essential.

-Stormwater Control Structures within outer drinking water source protection areas must be designed to remove contaminants of concern and consider site constraints.

For example: bioretention cells may be used to treat parking lot runoff near wellhead protection areas.

The point – MS4s and Water Suppliers need guidance on selecting stormwater bmps that can treat exiswting and new stormwater pollutant loadings.

How Can MS4s Prioritize Stormwater BMPs that Protect Their Drinking Water Supplies?• Review priorities in MS4’s

Stormwater Management PlanPriorities should include:• Identifying stormwater

outfalls near drinking water sources and tributaries, especially receiving waters rated as Class 2B and Class 3 (Natural) Resource waters

• Sampling dry weather discharges in their MS4 to determine if illicit discharges exist

• Prioritize stormwater outfalls needing treatment

Burlington MA – Source Water Assessment

EPA Region I Stormwater BMP Performance Analysis document

Models stormwater BMPs used for retrofit situations. These models illustrate filtration components and predict decay of pollutants based on calibrations for different storm events and type of land use.

Model predicts decay of pollutants for zinc, total phosphorous, and TSS for different types of BMPs (gravel wetlands, bioretention cells, swales, porous pavement, and wet (and dry) retention ponds)

Models used to generate long-term cumulative performance estimates expressed as performance curves. For each BMP, performance curves were developed for five land uses and three water quality constituents. The land uses consist of commercial, industrial, high-density residential, medium-density residential, low-density residential.

• EPA Stormwater BMP Performance Analysis document at www.epa.gov/region1/npdes/stormwater/assets/pdfs/BMP-Performance-Analysis-Report.pdf

Contact Information

EPA New EnglandDrinking Water Source ProtectionTed Lavery(617) 918-1683Lavery.ted@epa.gov

Sources of In formation for Evaluating BMP Performance • Technology Acceptance Reciprocity Partnership (TARP)

Protocol for Stormwater Best Management Practice Demonstrations:www.dep.state.pa.us/dep/deputate/pollprev/techservices/tarp/pdffiles/Tier2protocol.pdf

• Massachusetts STEP: http://www.mastep.net/library.cfm

• UNH BMP Specifications and Performance Information:http://www.unh.edu/erg/cstev/fact_sheets/index.htm

• EPA Urban BMP Performance Tool:http://cfpub.epa.gov/npdes/stormwater/urbanbmp/bmpeffectiveness.cfm

EPA Office of Water Updates- Draft Rulemaking for New Construction

Activities• Published Federal Register notice describing rulemaking considerations and

announcing listening sessions (Dec. 28, 2009)• Conducted five listening sessions and national webcast (2,000 participants)

Jan. – March 2010• Established docket for people to submit comments and information (access

through the website)• Schedule:

– Proposal in September 2011– Final Action in November 2012

• Met with numerous groups to discuss effort and gather input• Monthly meetings with States

www.epa.gov/npdes/stormwater/rulemaking

Considerations for Post-Construction Stormwater Rulemaking• Should EPA expand area of coverage to include

rapidly developing areas?

• Should EPA set a more specific standards on post-construction?

• Should EPA combine Phase I and Phase II MS4requirements to be consistent?

• Should EPA set retrofits requirements for urban areas?

Information Collection RequestEstimated Total Number Survey Sample

NPDES permitting authorities

Authorized states (46), Non-authorized states, EPA is authority (DC, ID, MA, NH, NM)

All

Regulated Phase I and II MS4s

Phase I - 750Phase II - 5891

Phase I - 266Phase II - 342

Regulated Transportation MS4s- State or County DOTs

149 84

Unregulated cities, towns, townships, villages, counties

16,335 932

Owners, operators of developed sites (long/short version)

739,547 2,985

Stormwater Infiltration Systems New England SetbacksState Wellhead Protection Area Surface Water Drinking Supply

Connecticut Prohibited within 100 ft of a public well Prohibited within 200 ft of surface watersupplies and their tributaries 100 ft

Maine Prohibited in contributing area of a publicsupply well

Allowed with treatment requirements

Massachusetts Prohibited in Zone I (Immediate WellheadProtection Areas)

Allowed in Zone II or Interim WellheadProtection Areas with additionalPretreatment

Prohibited in Zone A Surface Water SupplyProtection Area (400 ft around Class A sourceand 200 ft around tributaries to source)

Allowed in Zone B Surface Water SupplyProtection Areas with additional pretreatment.(Within ½ mile of Class A surface water source)

New Hampshire Prohibited within given setbacks from awater supply wells ranging from 75 – 400ft.

Prohibited in groundwater protection areaswhere the stormwater comes from a high-load areas

No infiltration to ground water suppliesfrom high-load areas

Prohibited within water supply intake protectionarea (area 250 ft of normal high water mark) orto ground water within 100 ft of surface water

Allowed within a water supply intake protection area if, the seasonal high water table andbedrock are at least 4 feet below the bottom ofthe practice

Rhode Island Prohibited within 400 ft of a public watersupply well

Prohibited within 200 ft of surface watersupplies and their tributaries

Vermont Prohibited within 500 ft of a publiccommunity water supply well

Prohibited within 500 ft of a public communitywater supply

Stormwater - Information Collection Request (Fall 2010) Survey Questions for Municipalities

Does your MS4 contain any stormwater discharges to a state-defined source water protection area?

Does your MS4 exclude areas from stormwater infiltration due to concerns about ground water contamination or mobilization of contaminated sediments?

Does your MS4 have ordinances in place that prevent stormwater retention practices, such as restrictions to sole source aquifers, water rights issues which prevent infiltration or restrictions related to ground water contamination prevention.

40 CFR Part 450 Effluent Limitations Guidelines and Standards for the Construction and Development Point Source Category; Final Rule

• http://water.epa.gov/scitech/wastetech/guide/construction/index.cfm

For More information on the New Construction Stormwater Rulemaking

see: