Stormwater Source Control Design Guidelines 2005 - Waterbucket

Stormwater Source Control Design Guidelines 2005Infiltration Swale13. Minimum freeboard to adjacent paving: 100mm or inaccordance with swale conveyance design.14. Treatment soil depth: 450mm is desirable, minimum150mm if design professional calculates adequatepollutant removal (Maryland Dept. EnvironmentalResource Programs, 2001), or 100 min. growing mediumover 100mm min washed sand (MUNLV-NRW, 2001).15. Drain rock reservoir bottom shall be level.16. Underground weirs (Figure 2A) of undisturbed nativematerial or constructed ditch blocks shall be provided tocreate underground pooling in the reservoir sufficient forinfiltration performance.17. A non-erodible outlet or spillway must be established todischarge overflow (Maryland Dept. EnvironmentalResource Programs, 2001).18. Avoid utility or other crossings of the swale. Where utilitytrenches must be constructed crossing below the swale,install trench dams to avoid infiltration water following theutility trench.Design OptionsDrain rock reservoir and underdrain may be deleted whereinfiltration tests by the design professional taken at the level ofthe base of the proposed construction show an infiltration ratethat exceeds the maximum inflow rate for the design storm.The attached Drawings 2B through 2D, and the InfiltrationSwale System Summary Poster illustrate the options.Photo Credit: Water Concept KronsbergPhoto Credit: Water Concept KronsbergSwale with check dams underconstruction.Swale with check dams in operation.Greater Vancouver Sewerage & Drainage District35