1. low impact development strategies and techniques jennifer j. bitting, pe the low impact development center, inc. june 2008

2. outline hydrologic analysis low impact development (lid) site planning strategies lid best management practice selection

3. hydrologic analysis lid hydrologic considerations lid hydrologic evaluation steps

4. hydrologic considerations runoff volume control peak runoff rate control flow frequency/duration control water quality control Q T Runoff Hydrograph Pre- development Post development

5. hydrologic analysis lid hydrologic considerations lid hydrologic evaluation steps

6. hydrologic evaluation steps 1.delineate the watershed and microwatershed areas 2.determine design storm 3.define modeling technique to be used 4.evaluate predevelopment conditions (baseline) 5.evaluate site planning benefits 6.evaluate lid practice benefits 7.evaluate supplemental needs

7. outline hydrologic analysis low impact development (lid) site planning strategies lid best management practice selection

8. lid site planning strategies define development envelope and protected areas reduce limits of clearing and grading use site fingerprinting use drainage as a design element minimize impervious areas disconnect impervious areas increase flow path length

9. define development envelope and protected areas

10. reduce limits of clearing and grading

11. use site fingerprinting place buildings in areas of poor draining soils save soils that drain well for groundwater recharge

12. use drainage as a design element Source: “Art for Rain’s Sake,” Landscape Architecture Magazine, September 2006

13. minimize impervious areas alternative roadway layout narrow road sections reduce sidewalks to one side of the road reduce on-street parking reduce rooftop area design driveways to be: shared narrow short permeable 53.32 acres of public street 82.35 acres of public street 35% difference

14. minimize impervious areas alternative roadway layout narrow road sections reduce sidewalks to one side of the road reduce on-street parking reduce rooftop area design driveways to be: shared narrow short permeable Source: Seattle Public Utilities http://www.seattle.gov/util/About_SPU/Drainage_&_ Sewer_System/Natural_Drainage_Systems/Street_ Edge_Alternatives/SPU_001805.asp

15. minimize impervious areas alternative roadway layout narrow road sections reduce sidewalks to one side of the road reduce on-street parking reduce rooftop area design driveways to be: shared narrow short permeable Source: Seattle Public Utilities http://www.seattle.gov/util/About_SPU/Drain age_&_Sewer_System/Natural_Drainage_Sy stems/Street_Edge_Alternatives/SPU_00180 5.asp

16. minimize impervious areas alternative roadway layout narrow road sections reduce sidewalks to one side of the road reduce on-street parking reduce rooftop area design driveways to be: shared narrow short permeable Source: Seattle Public Utilities http://www.seattle.gov/util/About_SPU/Drain age_&_Sewer_System/Natural_Drainage_Sy stems/Street_Edge_Alternatives/SPU_00180 5.asp

17. minimize impervious areas alternative roadway layout narrow road sections reduce sidewalks to one side of the road reduce on-street parking reduce rooftop area design driveways to be: shared narrow short permeable

18. disconnect impervious areas disconnecting roof drains and directing flows to vegetated areas directing flows from paved areas to stabilized vegetated areas breaking up flow direction from large paved surfaces encouraging sheet flow through vegetated areas

19. disconnecting roof drains and directing flows to vegetated areas directing flows from paved areas to stabilized vegetated areas breaking up flow direction from large paved surfaces encouraging sheet flow through vegetated areas disconnect impervious areas

20. increase flow path length maximize overland sheet flow lengthen flow paths increase vegetation minimize slopes increase surface roughness

21. increase flow path length maximize overland sheet flow lengthen flow paths increase vegetation minimize slopes increase surface roughness

22. increase flow path length maximize overland sheet flow lengthen flow paths increase vegetation minimize slopes increase surface roughness

23. increase flow path length maximize overland sheet flow lengthen flow paths increase vegetation minimize slopes increase surface roughness

24. outline hydrologic analysis low impact development (lid) site planning strategies lid best management practice selection

25. lid bmps bioretention filter strips vegetated buffers bioswale/grassed swale rain barrels cisterns green roofs porous pavement

26. bioretention source: http://www.cuyahogaswcd.org/grantfunded-raingardens.htm source: http://www.artfulrainwaterdesign.net/projects/

27. green roofs source: http://www.wsud.org/Pic_Pages/Green_roofs.htm source: http://www.thisoldhouse.com/toh/photos/0,,1599531,00.html extensive intensive

28. vegetated buffers source: http://www.sf.adfg.state.ak.us/SARR/restoration/techniques/intro.cfm

29. cistern source: http://www.tfssolar.com/134/sonora-co-housing-residence/

30. rain barrel source: http://www.iaswcd.org/district_tools/PWQ/temp/PWQ/PathwayBarrel.htm source: http://johnwesleymillercompanies.com/tucson-water.html

31. bioswale / grassed swale source: http://www.fceo.co.franklin.oh.us/images/Bioswale.jpg source: http://www.wbdg.org/resources/lidtech.php

32. porous pavement source: http://www.metrokc.gov/kcdot/roads/en g/lid/militaryS272/porousconcrete.cfm source: http://www.paving.org.uk/permeable.php source:http://www.hort.cornell.edu/UHI/outreach/ index.html

33. vegetated filter strip source:http://www.wsdot.wa.gov/Environment/WaterQuality/Research/Reports.htm

34. lid best management practices selection 1.define hydrologic control required. 2.evaluate site constraints. 3.screen for candidate practices. 4.evaluate candidate bmps in various configurations. 5.select preferred configuration and design. 6.supplement with conventional controls, if necessary.

35. define hydrologic control required runoff volume peak discharge frequency and duration of discharge groundwater recharge requirements water quality goals

36. evaluate site opportunities and constraints space required soil type slopes depth to groundwater proximity to foundations

37. select practices technical feasibility economic considerations construction maintenance waste disposal social aspects shade noise reduction environmental impacts air pollution

38. evaluate bmps in various configurations check the combination of bmps for compliance with hydrologic goals adjust the number and size of the bmps until the hydrologic goals are met

39. lid best management practice selection 1.define hydrologic control required. 2.evaluate site constraints. 3.screen for candidate practices. 4.evaluate candidate bmps in various configurations. 5.select preferred configuration and design. 6.supplement with conventional controls, if necessary.

40. three aspects of lid hydrologic analysis lid site planning strategies lid best management practices establishes the goal uses site features to achieve the goal adds additional measures to meet the goal