Storm Sewer Systems. Where precluded from handling runoff with open channels by physical site constraints, or as directed in Section 12 of Book 2, Developer shall design enclosed storm sewer systems to collect and convey runoff to appropriate discharge points. Developer shall prepare a storm sewer drainage report for the entire storm sewer systems that shall contain, at a minimum, the following items: • Drainage area maps for each storm drain inlet with pertinent data, such as boundaries of the drainage area, topographic contours, runoff coefficients, time of concentration, and land use with design curve number and/or design runoff coefficients, discharges, velocities, ponding, and hydraulic grade line data. • Location and tabulation of all existing and proposed pipe and drainage structures. These include size, class or gauge, catch basin spacing, detailed structure designs, and any special designs. • Specifications for the pipe bedding material and structural pipe backfill on all proposed pipes and pipe alternates. • Complete pipe profiles, including pipe size, type and gradient; station offsets from the centerline of the roadway; length of pipe; class/gauge of pipe; and numbered drainage structures with coordinate location and elevations. This report shall be a component of the Drainage Design Report.
Storm Sewer Systems. Under GMA35 storm sewers are not rural facilities; and in general, it is not appropriate for them to be extended or expanded outside of UGAs except in those limited circumstances shown to be necessary to protect basic public health and safety and the environment and when such services are financially supportable at rural densities and do not permit urban development. Therefore this section presents storm sewer systems under two subsections: Within UGAs, and Countywide.
