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Building Better Communities:

Building Better Communities:. A Municipal Responsibility. Building Better Communities: A Municipal Responsibility. Your Local Soil and Water Conservation District. Building Better Communities A Municipal Responsibility. STORMWATER MANAGEMENT

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Building Better Communities:

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  1. Building Better Communities: A Municipal Responsibility

  2. Building Better Communities:A Municipal Responsibility Your Local Soil and Water Conservation District

  3. Building Better CommunitiesA Municipal Responsibility STORMWATER MANAGEMENT The control and management of stormwater to minimize the negative effects to people, property, and natural resources

  4. Stormwater Management • To understand how we impact and are impacted by water, the concept of the water cycle is key. Source: Delaware Dept. of Natural Resources

  5. Stormwater ManagementWe Are All Connected! • All of us live in watersheds that have been impacted as a result of our activities on the land. Source: Natural Resources ConservationService

  6. Stormwater ManagementWe are All Connected! There are two basic elements of stormwater management. • Water Quantity Volume Rate of Release • Water Quality Source: NRCS Plainfield

  7. Stormwater Management Changes in Watershed Hydrology as a Result of Urbanization

  8. RUNOFF RATES AND VOLUMES PRE-DEVELOPMENT DEVELOPED W/O DETENTION DEVELOPEDW/ DETENTION ADDITIONAL VOLUME OF RUNOFF FLOW TIME

  9. Stormwater Management • Primary Objectives of Stormwater Management 1. Minimize water quality degradation 2. Minimize downstream channel erosion and habitat loss 3. Maintain natural base flows and groundwater recharge

  10. Stormwater Management Primary Objectives Continued: 4. Prevent increases in downstream flooding 5. Provide opportunities for multiple use of drainage and storage facilities 6. Provide for economical, safe, aesthetic, and socially acceptable drainage within new developments.

  11. Stormwater Management • Stormwater Management planning will preserve beneficial uses of downstream water bodies but also reduce drainage system construction costs. It eliminates the need for expensive capital improvements to existing drainage systems.

  12. Benefits of Stormwater Management • Prevent harmful impacts from periodic flooding including loss of life and property associated with threats and inconveniences to public health, safety and welfare. • Meet the requirements of federal, state, and local regulatory programs.

  13. Benefits of Stormwater Management • To assure that development does not increase flood and drainage hazards to others, or create unstable conditions susceptible to erosion • To protect, conserve, and promote the orderly development of land and water resources • Protect buildings and improvements to buildings from flood damage to the greatest extent possible

  14. Benefits of Stormwater Management • Conserve the hydrologic, hydraulic, water quality and other beneficial functions of flood-prone areas, regulatory floodplains and wetlands • Maintain eligibility for the National Flood Insurance Program by meeting requirements to ensure reduced rates

  15. Runoff Reduction Hierarchy • Preservation of natural resource features of the development site; • Preservation of existing natural streams, channels, and drainageways; • Minimize impervious surfaces; • Use open vegetated channels to convey stormwater runoff;

  16. Runoff Reduction Hierarchy • Preservation of natural infiltration and storage characteristics of the site; • Structural measures that provide water quality and quantity control; • Structural measures that provide only quantity control and conveyance.

  17. Stormwater Management Best Management Practices WATER QUANTITY

  18. Dry Detention Basin Rock Check Dam Grass Lined Channels Level Spreader Subsurface Drains Permeable Pavement Diversions Temporary Slope Drain Temporary Swale Stormwater ManagementWater Quantity BMPs

  19. Stormwater Management Water Quantity BMPs • A dry detention basin is a permanent stormwater management facility that temporarily stores incoming stormwater runoff and discharges it through an outlet structure to a downstream conveyance system. Source: Green Book Slide Set

  20. Stormwater ManagementWater Quantity BMPs • The purpose of a dry detention basin is to delay stormwater runoff peaks. It reduces potential flooding and erosion. They are not suitable for infiltration or groundwater recharge measures. Source: North Cook SWCD

  21. Stormwater Management Water Quantity BMPs • A rock check dam is a small rock dam constructed across a grassed swale or road ditch. Source: NRCS Plainfield

  22. Stormwater Management Water Quantity BMPs • The purpose of a rock check dam is to reduce the velocity of concentrated stormwater flows, reducing erosion of the swale or ditch, trap sediment generated from adjacent areas and to increase infiltration. Source: North Cook SWCD

  23. Stormwater Management Water Quantity BMPs • A grass-lined channel is a natural or constructed channel that is shaped or graded to required dimensions and established with suitable vegetation for stable conveyance of runoff. Source: Green Book Slide Set

  24. Stormwater Management Water Quantity BMPs • The purpose of a grass-lined channel is to convey and dispose of concentrated surface runoff without damage from erosion, deposition, or flooding. Source: Northeastern Illinois Planning Commission

  25. Stormwater Management Water Quantity BMPs • A level spreader is a device used to disperse concentrated runoff uniformly over the ground surface as sheet flow. Source: Conservation Design Forum

  26. Stormwater Management Water Quantity BMPs • The purpose of a level spreader is to convert concentrated, potentially erosive flow to sheet flow and release it uniformly over a stabilized area or filter strip. Source: Conservation Design Forum

  27. Stormwater ManagementWater Quantity BMPs • A subsurface drain is a conduit such as corrugated plastic tubing, tile, or pipe, installed beneath the ground surface to collect and/or convey drainage water. Source: NRCS Plainfield

  28. Stormwater Management Water Quantity BMPs • The purpose of a subsurface drain is to improve the soil environment for vegetative growth, reduce erosion, and improve water quality when used as part of other BMPs. Source: Green Book Slide Set

  29. Stormwater ManagementWater Quantity BMPs • Permeable pavement is pavement consisting of structural materials having regularly interspersed void areas. The voids are filled with pervious materials such as vegetated soil, gravel or sand. Source: Unilock Corporation

  30. Stormwater Management Water Quantity BMPs • The purpose of permeable pavement is to reduce runoff and pollutants from low-volume traffic areas by providing load bearing surface to accommodate vehicles and allow infiltration and filtration of pollutants. Source: Conservation Design Forum

  31. Stormwater ManagementWater Quantity BMPs • A diversion is a channel or supporting ridge constructed across the slope to collect and divert runoff. Source: Kane-DuPage SWCD

  32. Stormwater ManagementWater Quantity BMPs • The purpose of a diversion is to divert excess surface water from one area for use or safe disposal in other areas. Source: NRCS Plainfield

  33. Stormwater ManagementWater Quantity BMPs • A temporary slope drain is a flexible tubing or rigid conduit extending temporarily from the top of the bottom of a cut or fill slope. Source: North Carolina Erosion and Sediment Control Manual

  34. Stormwater ManagementWater Quantity BMPs • The purpose of a temporary slope drain is to convey concentrated runoff down the face of a cut or fill slope without causing erosion on or below the slope. Source: North Carolina Erosion and Sediment Control Manual

  35. Stormwater ManagementWater Quantity BMPs • A temporary swale is a excavated drainageway. Source: Green Book Slide Set

  36. Stormwater ManagementWater Quantity BMPs • The purpose of a temporary swale is to prevent runoff from entering disturbed areas by intercepting and diverting to a stabilized outlet it into a sediment-trapping device. Source: North Cook County SWCD

  37. Stormwater Management Best Management Practices Water Quality

  38. Stormwater Management Water Quality BMPs • In order to achieve water quality benefits: • Need to treat the “first flush” (e.g. first .5 inch of runoff) before releasing into wetlands or streams • Need to provide detention for 1 to 2 year frequency storm events in addition to the larger flood event (e.g. 100 year frequency storm).

  39. Inlet Protection Sediment Trap or Basin Culvert Inlet Protection Temporary Stream Crossing Site Dewatering Techniques Wet Detention Basin Stormwater Wetlands Filter Strip/Buffers Erosion Blankets Bioretention Extended Detention Stormwater Management Water Quality BMPs

  40. Stormwater ManagementWater Quality BMPs • Inlet Protection (catch basin insert) is a temporary sediment control barrier formed around a storm drain inlet. Source: Marathon Products

  41. Stormwater ManagementWater Quality BMPs • The purpose of inlet protection is to help prevent sediment from entering storm drains. Source: North Carolina Erosion and Sediment Control Manual

  42. Stormwater ManagementWater Quality BMPs • A sediment trap and/or basin is a small, temporary ponding basin formed by construction of an embankment or excavated basin. Source: Kane DuPage SWCD

  43. Stormwater ManagementWater Quality BMPs • The purpose of a sediment basin/trap is to detain sediment laden runoff from small-disturbed areas for a sufficient period of time to allow the majority of sediment and other water-based debris to settle out. Source: Kane DuPage SWCD

  44. Stormwater ManagementWater Quality BMPs • Culvert inlet protection is a temporary sediment filter located at the inlet to storm sewer culverts. Source: NRCS Plainfield

  45. Stormwater ManagementWater Quality BMPs • The purpose of culvert inlet protection is to prevent sediment from entering, accumulating, and being transferred by a culvert prior to permanent stabilization of a disturbed area. Source: NRCS Plainfield

  46. Stormwater Management Water Quality BMPs • A temporary stream crossing is a bridge, ford, or temporary structure installed across a waterbody for short-term use by construction vehicles or heavy equipment. Source: Kane DuPage SWCD

  47. Stormwater ManagementWater Quality BMPs • The purpose of a temporary stream crossing is to provide a means to cross waterbodies without moving sediment into streams, damaging the streambed or channel, or causing flooding. Source: North Carolina Erosion and Sediment Control Manual

  48. Stormwater ManagementWater Quality BMPs • Site dewatering techniques are practices designed to route sediment laden stormwater that has accumulated in active construction areas to a sediment filtering device prior to its leaving the site via a stormsewer, ditch, stream, etc. Source: Kane DuPage SWCD

  49. Stormwater ManagementWater Quality BMPs • The purpose of site dewatering is to remove groundwater or collected surface water from a site without causing negative effects offsite. Source: McHenry County SWCD

  50. Stormwater ManagementWater Quality BMPs • A wet detention basin is a permanent stormwater management facility that includes a permanent pool of water for water quality and additional capacity above the permanent pool for detaining stormwater runoff. Source: Green Book Slide Set

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