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WAT�R QUALITY TREATMENT FACILITIES <br />Water quality treatment facilities will consist of a deep cell and a wedand treatment cell. <br />The deep cell will be situated underground in a wet vault which is sized to contain 85 <br />percent of the runoff volume for the 6-month, 24-hour design storm event for developed <br />conditions. The wedand treatment cell is situated above ground and has been sized to <br />hold 15 percent of the volume for the 6-month, 24-hoi�r design storm event for developed <br />conditions. The water quality facilities aze designed to trea! Phase 1 pavement runoff only <br />and to not collect and treat runoff from Phase I roof area. <br />Two pipe arch tanks are proposed to provide storage for the deep cell portion of the water <br />quality treatment system. Each cell is 100 feet long and provides a storage pool of less <br />than 6'. The deep cells will discharge into the wetla�d treatment cell which has a has a <br />permanent pool depth of 2.5 feeL The wetland treatment cell will dischazge into the <br />detention tank system. <br />The following parameters were used to design the water quality treatment facilities (see <br />appendix): <br />Phase 1 <br />Developed impervious area - pavement <br />Developed pervious area — landscape <br />Rainfall — G month <br />Developed Tc <br />Runof[ �: olume — 6 month <br />2.45 acres/CN 98 <br />034 acres/CN 86 <br />0.99" <br />63 min (default minimum) <br />7185 cf <br />�7��� P�s�- � <br />