3535 RIVERFRONT BLVD 2023-02-21 - Laserfiche WebLink

Table 11-4.2.1 Runoff Conveyance and Treatment BMPs by SWPPP Element (continued) Ele- Element Ele- Element Ele- ment #4 Ele- ment #8 Stab- Element ment Element BMP or Ele- #3 Install ment #7 Pro- ilize #10 #13 Protect Con- Sect- #6 Pro- Chan- 9 Con- Control Low Impact ment Name iment tect tect nels 1trol Pol- trol De- Devel- Flow Con- Slopes Drain and Out- lutants Water- opment Rates trols Inlets lets ing for High pH Water (p.412) BMP C200: Interceptor Dike and Swale Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the top or base of a disturbed slope or along the perimeter of a disturbed construction area to convey storm- water. Use the dike and/or swale to intercept the runoff from unprotected areas and direct it to areas where erosion can be controlled. This can prevent storm runoff from entering the work area or sediment-laden runoff from leaving the construction site. Conditions of Use Where the runoff from an exposed site or disturbed slope rnust be conveyed to an erosion control facility which can safely convey the stormwater. . Locate upslope of a construction site to prevent runoff from entering disturbed area. . When placed horizontally across a disturbed slope, it reduces the amount and velo- city of runoff flowing down the slope. . Locate downslope to collect runoff from a disturbed area and direct water to a sed- iment basin. Design and Installation Specifications . Dike and/or swale and channel must be stabilized with temporary or permanent vegetation or other channel protection during construction. . Channel requires a positive grade for drainage; steeper grades require channel protection and check darns. . Review construction for areas where overtopping may occur. . Can be used at top of new fill before vegetation is established. 2014 Stormwater Management Manual for Western Washington Volume ll- Chapter 4 -Page 3.31