Stormwater Best Management Practices (BMP’s) John Reimer City of Madison Engineering Department

Federal Regulations  The Water Pollution Control Act was first enacted in 1948  The Act was amended by the Federal Water Pollution Control Act (FWPCA) Amendments of 1972  This Act is now commonly known as the Clean Water Act (CWA)  Instituted a shift:  From reliance on violations of water and quality standards as the primary enforcement tool, to  Establishment of specific technology-based effluent limitations that are enforceable as permit conditions

 To attain a level of water quality that “provides for the protection and propagation of fish, shellfish, and wildlife, and provides for recreation in and on the water”  To make navigable waters free of pollutant discharges CWA Goals

 The CWA requires the Environmental Protection Agency (EPA) to:  Establish effluent limitations for the amounts of specific pollutants that may be discharged  Set limits based on water quality in order to control pollution (in cases where technology-based limits are not strict enough to make waters safe) EPA’s Role

Regulation  Section 402(p) - Establishes Framework for Regulating Storm Water Discharges Under: National Pollutant Discharge Elimination System To “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters.” (Section 101) Purpose

Typical Regulated Point Source Discharges Treated wastewater from POTWs, industries, private utilities Utility Water Discharges Stormwater

NPDES Permits for Point Sources  National Pollutant Discharge Elimination System (NPDES) permits:  Must be applied for and obtained by anyone discharging pollutants into U.S. waters (from any point source)  Specify the discharge standards and monitoring and reporting requirements that a facility must achieve for each point source or outfall  Require more stringent controls when toxic pollutants are discharged  Regulations for toxics are based on best available and economically achievable technology (Section 307)

NPDES Permits for Point Sources  Permits issued by this program utilize industrial effluent standards and water quality standards to establish discharge limits for industries and treatment plants.

NPDES Permits for Non-Point Sources  NPDES permit program expanded in 1992 to include storm water and other non-point source discharges, including:  parking and storage lots  agricultural storm water discharges

NPDES Permit Program  Goal: reduce negative impacts to water quality and aquatic habitat  Requirement: develop storm water pollution prevention plans (SWPPPs) or storm water management programs with minimum control measures  Implementation: use best management practices (BMPs)

NPDES Permits and TMDL  Can be made more stringent if the specific water body requires lower discharges to meet water quality standards under Total Maximum Daily Load (TMDL) regulations

What are TMDLs?  Total Maximum Daily Loads (TMDLs) represent the assimilative or load capacity of the receiving water, taking into consideration:  point sources of pollutants (wasteload)  nonpoint sources of pollutants (load)  natural background  surface water withdrawals

How are TMDLs expressed? TMDL =  WLA +  LA + MOS Where: WLA is the wasteload allocation LA is the load allocation and MOS is the margin of safety Amount of pollutants that a waterbody can assimilate without violating surface water quality standards or other target

Margin of Safety (MOS)  A required component of the TMDL that accounts for any lack of knowledge concerning the relationship between effluent limitations and water quality (40 CFR (c))  The MOS shall be expressed either as an internal modeling factor and/or as an explicit, separate factor (N.J.A.C. 7: (a))

Components of a TMDL  Source assessment  characterization and quantification as necessary  identify point, nonpoint and background sources  Water quality analysis  link pollutant sources & water quality: model  consider seasonal variation / critical conditions  TMDL calculations  loading capacity  margin of safety  load and wasteload allocations  Follow-up monitoring  Implementation  Public participation

When Are TMDLs Done?  TMDLs are required, under Section 303(d) of the federal Clean Water Act, to be developed for waterbodies that cannot meet surface water quality standards after the implementation of technology-based effluent limitations

Target for TMDL: SWQS for Phosphorus (mg/L) Numerical Criteria  i.Lakes: TP not to exceed 0.05 in any lake, pond, reservoir, or in a tributary at the point where it enters such bodies of water, except where site-specific criteria are developed (N.J.A.C. 7:9B-1.5(g)3)  ii.Streams: TP not to exceed 0.1 in any stream, unless it can be demonstrated that TP is not a limiting nutrient and will not otherwise render the waters unsuitable for the designated uses.

Rock River TMDL Total Phosphorus Load (lbs/yr)

Stormwater Management  Stormwater Quality – “how good”  Stormwater Quantity – “how much” Quantity is related to … Quality

Stormwater Management Standards  No new untreated storm water discharges allowed  Post-development peak flow discharge rates < pre- development peak rates  Remove 80% of average annual total suspended solids (TSS) load (post development)  Discharges from areas with higher potential pollutant loads require use of specific BMPs  Redevelopment sites must meet the Standards  Construction sites must utilize sediment and erosion controls

Stormwater Runoff “Non-Point Source” Pollution  Stormwater runoff picks up pollutants as it runs off impervious surfaces  Oils/Grease  Metal Particles  Pesticides  Pet Wastes/Pathogens  Nutrients  Excessive Sediment

Stormwater Quality Impacts  Increased wash-off of pollutants  Increased water temperature  Public Health and Recreation Impacts  Results in:  Decrease in aquatic life  Loss of vegetation  Loss of healthy streams for recreation  Declining quality of drinking water supplies

Water Quality – Stormwater Constituents  Sediment  Nutrients: nitrogen and phosphorous  Oil, grease, and organic chemicals  Bacteria and viruses  Salt  Metals

Common Misconception  Stormwater from roads and construction sites is directed to storm drains  Stormwater that enters a storm drain gets treated  Where does it really go?

Best Management Practices (BMPs) Structural Designs:  Stormwater Treatment Plant  Retention Basins (concentrated flow)  Detention Basins / Infiltration Basins  Diversion Ditches  Catch Basins / Check Dam  Porous Pavement  Constructed Wetlands  Oil / Water Separators  Rooftop Collection System  Infiltration ditches and grassy swales  Silt fence and hay bales (sheetflow only) Non Structural Designs  Land Use Planning  Wetland and Floodplain protection  Stormwater Protection Plan  Pre Construction / Post Construction Plans  Riparian Zone Buffers  Public Awareness  Increased regulation  Street Sweeping  Storm Drain Stenciling  Vegetated Rooftops Source: Mehler and Oskowski, 1999

Infiltration Basins  Removal Efficiency:  75-80%  Features:  Promotes groundwater recharge  Preserves natural water balance  Susceptible to clogging  Reduces downstream impacts  Generally used for small drainage areas  Maintenance: high  Cost: moderate to high

Bioretention (Rain Gardens)  Removal Efficiency:  75-80%  Features:  Divert initial flow and not used for flood control  Generally used for small drainage areas  Maintenance: high  Cost: moderate to high

Water Quality Swales  Removal Efficiency:  60-80%  Key Features:  Control peak discharge  Higher pollutant removal rates than drainage channels  Provide some infiltration  Maintenance: low to moderate  Cost: low to moderate

Inlets and Catch Basins  Removal Efficiency:  15-35%  Design Features:  Debris removal  Pretreatment  Maintenance: moderate to high  Cost: low to high

Sediment Traps/Forebays  Removal Efficiency:  25%  Design Features:  Pretreatment  Retrofit expansion  Larger space requirement than inlet.  Maintenance: moderate  Cost: low to moderate

Innovative BMPs - Hydrodynamic  Removal Efficiency:  50-80%  Design Features:  small area  Oil and Grease control  Maintenance: moderate  Cost: High

Innovative BMPs – Media Filtration  Removal Efficiency:  50-80% average  80% design  Design Features:  small area  Oil and Grease control  Maintenance: moderate  Cost: High

Innovative BMPs – Screen Treatment  Removal Efficiency:  15-35%  Design Features:  Debris removal  Pretreatment  Maintenance: moderate to high  Cost: low to high

Detention Basins  TSS Removal Efficiency:  60-80%  Key Features:  Large area  Peak flow control  Maintenance: low  Cost: low to moderate

Wet (Retention) Ponds  Removal Efficiency:  60-80%  Key Features:  Large area  Peak flow control  Maintenance: low to moderate  Cost: low to high

Constructed Wetlands  Removal Efficiency:  65-80%  Key Features:  Large area  Peak flow control  Biological treatment  Maintenance: low to moderate  Cost: higher than wet ponds

Other BMPS  Green roofs  Grassed/Porous Pavement

Non-Structural BMPs  Street sweeping  Storm water collection system cleaning and maintenance  Low impact development and land use planning  Snow and snowmelt management  Public Education

Construction Site Controls  Use of construction site controls protect water quality

Impacts of Sedimentation  Sediments can block culverts and displace flood waters  Bare soil easily washes into storm drains and into streams, clouding the water and suffocating aquatic life.

Erosion Control Practices Silt Fence Silt Sock Construction Entrance Check Dam Inlet Protection Erosion Matting

Questions