Laserfiche WebLink
Bill Murtay-fhainagc Study <br />\UATER QUALITY DESIGN CRITERIA <br />For a commcrcial with Icss than 10,000 sf of pro�sed pavement, thc water quality BMP <br />must bc addressal as a combination opcn/closed system. This statement assumes that it is <br />not practical for masons of topobnaphy, soil conditions, ctc. to disposc of the design <br />��olumc of runoff by infiltration. For the instant project, wnditions am as follows: <br />a. The total volumc must cqual ihc 6 mo.-24 hour storm; <br />For the Bill 111urny proposal, the rcquired volume ia 332 CF. <br />b. The Santa Barbara calculation method is acceptable; <br />c. The "pertnanent" pool storage volumc shall be equal to thc volume of runoff in <br />the 6-month WQ storm. In thc instant case, the volume cquals 332 cf for the 6- <br />month storm runoff from the asphalt surfaces. Pervious areas will not be directed <br />to thc stumi drains. <br />i. The maximum volume of thc open water cell is 85% of the �mancnt <br />pool volume. Max. Volume = O.RS * 332 ci= 282.2 cf. <br />The minimum of the shallow trcatment cell is I 5% of the pemianent pool <br />volume. Min. Volume = 0.15 * 332 cf = 49.8 cL The Treatment cell <br />must be 50 cf or grealer. <br />d. The wet pond water quality volumc is divide:; between an "open water" cell and a <br />wetland trealment cell The minimum depth in the open water cell shall be 3 fcet <br />decp; ln the instant case with less than I Q000 sf of pavcd surface area tributary to <br />detention, wc have selectcd a 3' diametcr storage ccll anchored with two 54" <br />manholes. Thc Opcn Ccll �vith 3:1 side slopes will bc placcd just inside the <br />Property Linc <br />wisn:rch i-�citieeas, rvc. raaecrui-n i-n ry <br />b <br />