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T <br /> Summary of San Joaquin County's Storm Drainage Design Standards <br /> s <br /> 3.3 Design Storm Runoff <br /> - TR-20 method is required to size detention basin. (3.31 E) <br /> Off-site flow must be determined. (3.33) <br /> Diversions must meet horizontal and vertical control off-site unless easement is <br /> approved. (3.34) <br /> 33.44 Hydraulic Criteria <br /> Detention Systems (3.45) <br /> Design for 100-year frequency. <br /> { - Gravity outlet controls will operate without any backwater effects under the design <br /> I storm. <br /> - Pump discharges are acceptable. A backup power generator is required. <br /> - Bottom of basin shall be 2 feet above the highest recorded ground water elevation. <br /> - The high water surface elevation of the basin shall be a minimum of 2 feet below <br /> all adjacent ground. <br /> 33.55 Dra� inage Structures <br /> Rock Lined Channels (3.56 C) <br /> Minimum 2:1 side slopes and conforming to the Standards and Specifications of <br /> the California Department of Transportation. <br /> Detention Systems (3.58) <br /> Maximum 4:1 side slopes. <br /> - Fenced if water depth is greater than or equal to 18 inches. <br /> - Minimum 10 foot wide access road. <br /> - Gravity outlet preferred. <br /> - Bottom slope shall be a minimum of one percent towards the outlet works. <br /> t <br /> ' Pump Stations <br /> Systems having pump stations shall be designed for gravity outflow during low flow <br /> periods unless gravity flow is impossible or impractical. <br /> 3 - For pump stations having gravity discharge,the pump capacity shall equal design <br /> inflow. Pump stations not having gravity discharge must be designed to fumish <br /> 100% of design discharge with the largest pump out of service. <br /> There are many specific requirements for the design of the pump station; refer to <br /> design standards. <br /> 3.6 Drainage Report <br /> Required for subdivision > 2 acres <br /> i <br /> 1 <br />