Laserfiche WebLink
_ 1: <br /> PUBL/C WORKS <br /> �r <br /> MEMORANDUM <br /> TO: Kirk Brooks <br /> FROM: Jane Zimmerman <br /> DATE: January 29, 1997 <br /> SUBJECT: Drainage Calculation Review, Wilder Construction Company, <br /> 1525 E Marine View Drive <br /> Detention• <br /> Per the MDNS, on-site detention is required per City standards unless there are no <br /> natural drainage systems between the site and the Snohomish River that would be <br /> impacted by the increased rate and volume of stormwater and the downstream drainage <br /> system has the capaciry to handle the additional runoff without causing erosion or <br /> flooding. The drainage analysis submitted considers only the pipe from this site and <br /> dcesn't analyze any drainage systems downstream of the pipe. <br /> If detention is required, release rates and detention volumes must be calculated using <br /> the site vegetative conditions which existed prior to the most recent ciearing and <br /> grading activities on the site. <br /> Wetpond: <br /> Wetpond calculations are required. <br /> 'The wetpond design volume is equal to the volume of runoff from the wetpond design <br /> storm (the 6 month, 24-hour storm). The following two methods are acceptable for <br /> determining the wetpond design volume: <br /> 1) multiply the area of impervious surface in the contributing basin by the <br /> precipitation associated with the design stornt, or <br />