What Does It All Mean? CWA? Sara Esposito, P.E. DNREC Division of Watershed Stewardship sara.esposito@state.de.us
Why are we here? Just like pavement has helped move cars faster; it has also helped water move faster<
How did we get here?
The causes: Changes in land use: From Grass & Forest to Paved & Managed
The causes: Changes in land use: From Grass & Forest to Paved & Managed Development in floodplains: The water has to go somewhere else
The causes: Changes in land use: From Grass & Forest to Paved & Managed Development in floodplains: The water has to go somewhere else Alteration of natural stormwater systems: Stream to Pipe & Ditches
The causes: Changes in land use: From Grass & Forest to Paved & Managed Development in floodplains: The water has to go somewhere else Alteration of natural stormwater systems: Stream to Concrete Pipe Compaction of soil, imperviousness Resulting in: Decreased Infiltration Decreased Plant/Tree Life Increased Speed of Runoff Increased Volume of Runoff Increased Pollutants
What are the solutions? First there was Drainage and then there was more Drainage Objective: Get the water away as fast as possible Solution: Ditch and pipe water away from farm fields and developments Problems: Created a Tax Ditch system in Delaware which created long, straight ditches with little ecological benefit; estimated that 30-50% of Delaware s original freshwater wetlands have been drained or filled for agricultural purposes. For developments, provided little to no stormwater treatment, just conveyance.
Then there was Stormwater Treatment In 1972, President Nixon signed the Federal Clean Water Act (CWA), which was amended in 1977 and 1987. Gave the U.S. Environmental Protection Agency (EPA) the authority to implement pollution control programs. Section 402 of the CWA created the National Pollution Discharge Elimination System (NPDES), which permitted point source discharges. The first point sources targeted were wastewater; stormwater was not overly addressed until the 1987 amendment. In 1991, Delaware passed the Sediment and Stormwater Regulations requiring controls for disturbance greater than 5,000 sf. Required erosion & sediment controls Required pre to post development runoff rate control Required 80% Total Suspended Solids (TSS) removal Created the stormwater pond as the golden child
Stormwater Pond Era Objective: Detain the water to the same discharge rate as existing. Solution: Create large holding tanks to store water and slowly release Problems: More volume of water could be discharged leading to flooding Point discharges cause erosion in streams Increased water temperatures, geese, algae blooms, etc
Then Disaster Strikes<
The current stormwater regulations do not adequately address volume management of stormwater. This program deficiency has been recently addressed by surrounding states with new program requirements. Increased emphasis on recharge and infiltration of stormwater where technically and environmentally feasible, has to be endorsed by changes to the existing body of law. - Gov. Task Force on Surface Water Management (2005) The Task Force for Surface Water Management identified legitimate public health, safety and welfare concerns associated with drainage and stormwater management. The proposed revisions to the Delaware Sediment and Stormwater Regulations represent the Department s efforts to address those concerns and recommendations through the State s regulatory authority.
At the same time Delaware realizes something s up, so do the Feds< In May 2009, President Obama signed Executive Order 13508 to protect and clean up the Chesapeake Bay. The 6 states that drain to the Bay (NY, PA, MD, DE, VA and WV) have to develop Watershed Implementation Plans (WIPs) that prescribe how they will bring their steams pollutants levels back to the Total Maximum Daily Load (TMDL) established for that area< ie, Pollutant Diet for the Bay.
Not just stormwater this time< The culprits: Sediment (TSS, or Total Suspended Solids): Clouds water, blocks light needed for bottom life. Once settled to bottom, suffocates bottom feeders. Sources: Bare soil that erodes away (construction sites, steep slopes, poorly vegetated areas); Stream bank erosion from increased flow. Phosphorus (TP): Excess amounts cause algae blooms (eutrophication), which blocks sunlight from entering the waterway. As the algae decays and falls to the bottom, oxygen is depleted during the decomposition, causing low dissolved oxygen levels, resulting in fish kills. Sources: Fertilizers, Manure/Wastewater Nitrogen (TN): Same effects as Phosphorus. Also restricts the transportation of oxygen in the bloodstream of mammals infants are most affected. Sources: Fertilizers, Septic Systems, Manure/Wastewater, Atmospheric Deposition Chesapeake Land Use in Delaware
How does it get there< Point sources Comes from a specific source, such as a pipe. Wastewater treatment plants, Stormwater pipes, etc. Nonpoint sources (NPS) Harder to pinpoint and address. Agricultural and residential fertilizer runoff, stormwater runoff
What are we doing to help< New Sediment and Stormwater Regulations: Will require the same volume of runoff as the pre-condition. Wooded, sandy soils don t produce a lot of runoff; to mimic that condition will need to infiltrate or reuse a lot of runoff. New stormwater BMP (Best Management Practice) specifications to promote infiltration and vegetation, ie, practices that mimic nature. Chesapeake WIP: Agricultural incentives for cover crops; converting wastewater treatment plants to spray irrigation; taking septic systems offline; increased CAFO (Confined Animal Feeding Operation) regulations, holding towns accountable for increased loads, etc.
What can you do to help< N P K Have your soil tested (through UD Ag Cooperative Extension, $10). Will indicate how much Nitrogen and Phosphorus is needed. Typically phosphorus is only needed for new lawns (most regular fertilzers don t contain phosphorus any more, ie, 10-0-10). Fertilize in the fall, less runoff and nutrients are available as soon the ground thaws. Reduce the amount of runoff from your lawn< Pavers instead of concrete. Raingarden instead of raised flower bed. Less turf, more native plants and trees. Rainbarrels or cisterns to reuse water. Get septic system inspected and pumped out if needed. Consider Backyard habitat programs, adopt-a-wetland, etc. Pick up Poop! Not just for your neighbors sake, but also for the environments.
Websites & Resources DNREC Sediment and Stormwater Website: http://www.dnrec.delaware.gov/swc/pages/sedimentstormwater.aspx DNREC Chesapeake WIP Website: http://www.dnrec.delaware.gov/swc/wa/pages/chesapeake_wip.aspx DNREC TMDLs Website: http://www.dnrec.delaware.gov/swc/wa/pages/watershedassessmenttmdls. aspx DNREC Watersheds Website: http://deldot.gov/stormwater/watershed.shtml Low Impact Design Guidance: http://www.epa.gov/owow/nps/lidnatl.pdf
Reduce Impervious Surfaces Maintain and Provide Buffers Construct Biofiltration Practices Create Natural Areas Leave Areas Undisturbed Cluster Development Conservation Design
Benefits of Conservation Design Increased Infiltration Rates over Traditional Development Habitat Preservation Open Space Preservation Enhanced Property Values
Biofiltration Swales Filter Strips Bioretention Infiltration Green Technology BMPs
Shallow depth of flow Flat bottom Vegetation height typically 6-8 Biofiltration Swales
Filter Strips Spread runoff uniformly over vegetation Best for treating small areas of impervious cover
Bioretention Landscaped depression Porous soil media Runoff infiltrates or discharges through underdrain Construction From the side After drainage area is stabilized
Permeable Pavement Store and recharge water quality volume Dry within 48 hours Rigorous soil testing
Other Green BMPs Rain Barrels / Cisterns Green Roofs Rain Gardens