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Grinder pumps shall be used when riser pipes in wet well are less than 3-inches. <br /> Minimum valve (all types) size is 4-inches. <br /> H. Wet wells shall be a minimum of 6-feet in diameter (ID). All wet wells shall be <br /> sized to provide a minimum pump cycle of 15 minutes. Pumps shall be designed <br /> to provide a minimum pump run time equal to half the cycle time. Additionally, <br /> wet wells shall provide sufficient space for installed equipment and required <br /> suction pipe submergence and spacing. The wet well floor shall have a minimum <br /> slope of one-to-one to the hopper bottom. <br /> I. A separate valve vault shall be provided to house the gate valves, check valves <br /> and the emergency pump connection. The vault shall be of sufficient size to <br /> allow for installation, removal and maintenance of the valves. The top of the <br /> valve vault shall be a minimum of 12-inches above the high water level of the <br /> associated development. The wet well top elevation and the valve vault top <br /> elevation shall be a minimum of 12-inches above the associated elevations <br /> shown on the FIRM (Flood Insurance Rate Map) or 12 inches above the 25-year <br /> —24-hour storm event elevation, whichever is greater. <br /> J. In IRCDUS maintained lift station, pumps shall be per the Approved <br /> Manufacturer's Product List. If a grinder pump is proposed, see Approved <br /> Manufacturer's Product List. Only grinder pumps under 5.0 hp are permitted <br /> unless approved by IRCDUS. <br /> K. Lift Station Calculation Checklist (all assumptions shall be listed in calculations <br /> and in an orderly fashion): <br /> 1. Design flow <br /> 2. Downstream force main size & down stream head pressure (in psi or feet <br /> of water) <br /> 3. TDH of pumps shall exceed system head curve <br /> 4. Pump selection make, model, HP, impeller <br /> 5. a. Wet well dimensions <br /> b. Operating cycle and draw down time <br /> 6. Buoyant computations Documentation: <br /> a. Buoyant force <br /> b. Downward force <br /> c. Safety factor <br /> d. Depth to water table <br /> 7. Designer name, date, design firm, Indian River County project number, <br /> project name, designer name of revisions <br /> L. Only one influent gravity main is allowed into the lift station. The first upstream <br /> manhole from the lift station must be located within 20 feet +/- 1-foot of the lift <br /> station and as approved by IRCDUS. <br /> M. The owner of a private lift station must have a maintenance agreement with a <br /> qualified firm (individual) to maintain the lift station. A label must be posted on <br /> the lift station stating the name and 24-hour phone number of the responsible <br /> firm before lift station may be placed into operation. A copy of a maintenance <br /> contract is to be submitted prior to issuance of the Utility Construction Permit. <br /> 14 - 3 <br />