Laserfiche WebLink
� Flow Control and Watcr Trcatment Facilities: <br /> The proposed conveyance system drains into an existing 8" combined sanitary <br /> sewer/storm drain line. As such, water quality is not required for this site other than an <br /> oil-water separator to treat runoff from the vehicle wash d wn area. The water qualiry � <br /> design standards for the oil/water separator are in accordan � with the City of Everett I <br /> `Design and Conswction Standards and Specifications fo� �evelopment' (Drawing <br /> Index, Series 400) revised for October 2000. All drainage for the site is routed to wnnect <br /> to the existing 8" combined sewer line in the north alley running through the site as <br /> preliminary information indicates that the 8" combined sewcr line in the south alley is <br /> currendy near capacity. No flow control facilities arc proposed as th� additional <br /> impervious arca of the site ovcr existing conditions will be 1,300 square feet. <br /> Offsite Drainage Description: <br /> The analysis performed for this report does not have any offsite drainage directly <br /> contributing ro the sitc. I <br /> I <br /> ( Convcyancc System: ( <br /> The conveyance system is designed in accordance with the standards oudined in the <br /> wrrent Everett Stormwater Management Manual. As required, the 25-year design stortn <br /> event with an annual precipitation of 2.60 inches in 24 hours is used to determine the size <br /> of the stortnwater pipes. Altached is a table indicating catch basin collection areas and <br /> their respective pervious and impervious areas with the basins associated runoff <br /> coefficient value. From each of the catch basin's respective area, weighted "C" values <br /> are obtained and used in the conveyance calculations. The attached convcyance table <br /> shows that the proposed siorm drain system has adequate capacity to convey the <br /> developed ilo�vs on the site. Also note the new storm lines on Rainier Avenue and <br /> McDougal Avenue are added to accommodate the runoff resulting from the addition of <br /> parking stalls in the right-of-way. These two new storm lines are also able to convey the <br /> 25-year storm event. <br /> r:�, <br /> C <br /> , �� <br />