Presented by Sheri Lott Watershed Steward Student December
Presented by: Sheri Lott Watershed Steward Student December 1, 2015
Topics of Discussion �The history of ponds – BMP evolution �Why do we need stormwater ponds? �What is a stormwater pond and how does it work? �How effective are stormwater ponds? �How do you identify a failing pond? �What can you do about a failing pond? �Questions
What initiated the need for stormwater ponds? • INCREASED RUNOFF/INCREASED IMPERVIOUS SURFACE = • FLOODING OF PROPERTIES DOWNSTREAM • EROSION OF STREAM BANKS • SEDIMENT BUILDUP • INCREASED POLLUTANTS IN STREAM = • DECREASE IN WATER QUALITY; • DECREASE IN HABITAT AND WILDLIFE
What is a stormwater pond and how does it work? �Dry Pond � Detains Water � Slow Release typ over 24 hours by a Control Structure vs. �Wet Pond � Retains Water � Typically 2 Cells � Has Permanent Wet Pool � Water Quality – � Settlement � Phytoremediation
Dry Ponds
Older Wet Ponds • • Improved Water Quality vs. Dry Ponds Can be Erosion and Sediment Control – Sediment Basins
Example of Older Wet Pond
Two-Cell Wet Ponds • • Improved Water Quality vs. Dry Ponds and One Cell Wet Ponds Can be Erosion and Sediment Control – Sediment Basins
How a Pond Fits into Modern Design High Point Redevelopment Seattle Washington
Example of a Pond In Series High Point Redevelopment Seattle, Washington
How effective are stormwater ponds? �Quantity vs. Quality �Pollutant Removal Mechanisms: Settling, Filtering, and Biological Processes BMP Dry Detention Ponds TN TP TSS 5% 10% Wet Ponds 20% 45% 60% Infiltration Practices 50% 60% 90% Green Roofs 50% 60% 90% Rainwater Harvesting 50% 60% 90% Rain Gardens 50% 60% 90% From Table 4. MDE - Accounting for Stormwater Wasteload Allocations and Impervious Acres Treated
Identifying a failing pond �Downstream erosion, flooding, sediment buildup, eroded stream banks �Corroded Pipes/Outlet Structures �Blockages
What can you do about a failing pond? �Repair/replace failing structures �Reduce Impact/Stress -Introduce Upstream BMPs �Infiltration practices �Rainwater Harvesting �Behavioral Changes �Trash Control
Rainwater Harvesting
Less Lawn = Xeriscaping
Less Lawn = Rain Garden
Behavioral Changes
Trash Control - Downstream
Trash Control – Upstream/Behavioral Change
Questions ?
- Slides: 20