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Ponds and Stormwater in Prince William County: A Homeowners Perspective

Ponds and Stormwater in Prince William County: A Homeowners Perspective. Frank Reilly. Why Me?. Army Engineers Waterways Experiment Station 10 Years of Wetlands Workshops www.WetlandsWorkGroup.org 10 Years as a Prince William Virginia Cooperative Extension Master Gardener

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Ponds and Stormwater in Prince William County: A Homeowners Perspective

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  1. Ponds and Stormwater in Prince William County:A Homeowners Perspective Frank Reilly

  2. Why Me? • Army Engineers Waterways Experiment Station • 10 Years of Wetlands Workshops • www.WetlandsWorkGroup.org • 10 Years as a Prince William Virginia Cooperative Extension Master Gardener • www.advancedmastergardener.org

  3. Precipitation Runoff Infiltration Evaporation Review

  4. What happens to the Rain? • Depends on many factors: • Rate of rainfall • Soil conditions (Dry, Damp, Soggy) • Density of vegetation • Amount of urbanization • Topography

  5. Natural Conditions

  6. Developed Conditions

  7. More impervious surface = more runoff

  8. So What? • Degraded habitat • bacteria, sediments, nutrients, and petroleum products • Impaired watersheds • Loss of habitat • Silting in wetlands • Destruction of SAV • Oyster reef • Increased regulation • TMDLs • Rain tax

  9. So what for me? • Flooding

  10. So what for me? • Flooding • Stormwater maintenance

  11. So what for me? • Flooding • Stormwater Tax • Personal damages

  12. Hydrograph Developed Condition, Conventional CN (Higher Peak, More Volume, and Earlier Peak Time) Q Existing Condition T

  13. 1 inch of rain falling on 1 acre = 27,154 gallons of water

  14. How can we make residential developmentsfunction hydrologically like natural systems?

  15. During A One Inch Rainstorm: • 25,800 gallons of water runs off a one-acre parking lot. • 1,361 gallons of water runs off a one-acre wooded area.

  16. Stormwater Management Facilities (SWM) Bioretention (rain garden) Dry Detention Facilities Trench Underground Facilities Wet Detention Facilities

  17. Storm water Facilities • Prince William County has record of: • 450 Commercial SWM/BMP facilities • Wet ponds • Dry ponds • Sand filters • Underground filters (Stormceptor, etc.) • Other

  18. Storm Drainage and Stormwater Management • Storm Drainage Systems • Pipes • Inlets • Stormwater Management Facilities (SWM)

  19. Dry Pond/ Wet Ponds Dry Pond Facilities • Used in smaller drainage areas • Smaller land area • Less effective pollutant removal • Extended Detention (BMP) 48 – 72 hrs Detention • Fencing/signage required • Easier maintenance

  20. Dry Pond/ Wet Ponds Wet Pond Facility • Larger drainage area • Permanent pool of water • Aesthetically pleasing • Water level rises with storm • Better sediment/ pollutant removal • Signage required • No fencing required

  21. Property Owners Maintenance Responsibilities Long Term: • Dredging • Structure repairs • Embankment (compaction, seeps, etc.) • Major vegetation removal • Spillway Pipe/ Outfall Channel • Erosion

  22. Safety • Safety - Water rises rapidly • Fencing – Minimum 4 foot high chain link fence • Gate - 15 foot wide gate with lock where the access road enters the facility • Signage – Warning signs • Access Road - VDOT standards • Access < 10% slope- 6” gravel • Access >10% slope -asphalt

  23. Problem Prevention • Sediment/ Nutrient reduction • Filter strips • Fertilizer reduction • Aeration • Trash removal (debris rack) • Woody vegetation removal (periodic) • Adjacent property impact

  24. Algae Problems • Excess nutrients cause algae growth • Prevention • Grass/vegetation filter strips can filter nutrients • Nutrient Management (IPM) • Removal • Chemical • Mechanical

  25. Challenges of traditional stormwater management include: • Engineering, design and infrastructure can be more costly than mimicking natural systems • Maintenance can be more expensive • Significant space required for detention ponds • Flow and volume of stormwater may not be adequately controlled, leading to: • Erosion • Flooding • Slope destabilization

  26. So what is the problem?As stormwater flows it picks up and transports: • Sediment • Pet waste • Salt • Pesticides • Fertilizer • Oil and grease • Litter • Leaves • Heat

  27. Sediments • Soil particles carried by rainwater into streams, lakes, rivers and bays • By volume it is the greatest pollutant.

  28. Nitrogen and Phosphorus • Sources • Fertilizer • Natural vegetation • Animal waste • Promote algae blooms • Decaying algae depletes oxygen levels in water.

  29. Litter & Debris • Clogs BMP control • Can cause back-up of water & dam deterioration • Degrades aesthetic qualities • Decomposes slowly • Physical danger to vegetation and wildlife

  30. Litter and other potentially toxic & lethal substances • Battery acid and antifreeze • Cleaning agents • Non-biodegradable packaging-Styrofoam, plastic bags • Cigarette butts

  31. Leaves • Decomposing leaves deplete the oxygen in streams. • If leaves build up in underground catch basins, a poisonous gas (hydrogen sulfide) can occur. • Please do not blow or rake leaves or grass clippings into the street!

  32. So what do we do? • Remove debris from storm drains regularly

  33. So what do we do? • Clean parking lots and paved areas of leaves, trash and sediment. • Sweep pavements- • And pick up the dirt-don’t sweep dirt into the gutter.

  34. So what do we do? • Reduce the amount of salt used in parking lots and walkways • Alternatives • use ice melt, sand, kitty litter, cinders or ashes

  35. So what do we do? • Clear snow from drains • Clear snow to the lower end of paved areas.

  36. So what do we do? • Collect and recycle hazardous waste oils, solvents etc. • Start a recycling program!

  37. Grass swale Green roof Rain Barrel Porous pavement Bioretention (rain garden) Low Impact Development (LID) • Goal is to absorb stormwater naturally

  38. In The Landscape--- • Fertilize cool season grasses in the fall not the spring. • Use the right amount of fertilizer • Leave the clippings

  39. In The Landscape--- • Do not apply fertilizers or pesticides near bodies of water, or before a rain. • Sweep up any residue from hard surfaces and dispose of properly.

  40. Just a few reminders -

  41. Partners For Water QualityProgram • Call Cooperative Extension • Carol A McElroy • 703-792-4037 • CMcElroy@pwcgov.org • 10% rebate on current years stormwater management fee

  42. Participating in • Adopt a stream or • Adopt a spot

  43. Questions?Prince William County Watershed Management Branch at (703) 792-7070

  44. Environmental Issues Wetlands Resource Protection Areas (RPA) Water Quality Stream Restoration

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