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� <br />� <br />� <br />Hoglunds Top Shop <br />Drainage Smdy <br />June 23, 2008 <br />WATER QUALITY <br />Existing &. New Building = 7,365 SF <br />� Conc. SW = 5�:0 SF <br />Asphalt Parking = 12 734 SF (0.29 Acresl <br />� Proposed Impervious Area = 20,689 SF 0.47 Acres <br />Tributazy Pervious = 876 SF (0.020 Acres) <br />� Asphalt Parking = 12,734 SF (0.29 Acres) <br />Treatment Area Tributary to Filters= 0.31 Acres <br />' <br />� <br />�_ <br />�� <br />l. <br />�. <br />Areas directed to Water Quality = Pavements & Landscaping = 0.31 acres <br />Proposed Polluting Surface Addition = 12,734 SF pavements. Historically this site lacked <br />any hydraulic connection to the public drainage system even though the City's 24" Storm <br />Drain was constructed with easement on the east edge of the property. Since these <br />surfaces were not previously connected to the downstream storm system the City has <br />required that the entire 12,734 SF of new pavement be treated prior to discharge to the <br />public conveyance. The 6-month storm from the new pavements was historically <br />i�ltrated or evaporated. This event will now be treated with commercial Storm Filters <br />mazketed by Contec and designed for this purpose. The existing & proposed rooftops will <br />be diverted directly to the downstream system via a sepazate roof drain system to avoid <br />the filters. <br />Water Quality Design Q's <br />6-month Strom Event Tributary to Filters = 0.05 CFS (22.44 GPM) <br />2-yeaz Q = 0.087 CFS <br />100-Yeaz Q = 0.199 CFS <br />Filters aze the lazge 27" size with a minimum Head of 3.0 feet on the outlet. <br />Produ�t treatment capacity is 11.25 gaUfr^2 <br />Twin cartridges will treat 22.5 gaUft^2 <br />See associated C�NTEC design information in the Appendices. <br />