S.C. Code Regs. § § 61-56.502
Current through Register Vol. 48, No. 11, November 22, 2024
Section 61-56.502 - Onsite Wastewater Pump System Standard502.1. Pump Tank (General). (1) The submersible sewage effluent pump(s) must be housed in a properly vented, watertight tank that is readily accessible from the surface.(2) A watertight access opening with removable lid shall be provided and shall be designed and maintained to prevent surface water inflow. Risers and other pump tank sections, where present, shall be joined using mastic, butyl rubber, or other pliable sealant that is waterproof, corrosion-resistant, and approved for use in septic tanks.(3) When the pump tank must be located in an area characterized by a shallow zone of saturation, the Department may require the use of a pre-cast manhole, a fiberglass or polyethylene basin, or any other acceptable method for preventing groundwater intrusion.(4) When the pump tank must be located in an area that is environmentally sensitive or subject to flooding, applicable portions of R.61-67, Standards for Wastewater Facility Construction, shall apply.(5) The pump tank shall have sufficient capacity to accommodate all level control and alarm switches; to keep the pump(s) totally submersed in liquid at all times and to provide the required dosing volume and minimum pump run time. Pump tank capacity must be at least 500 gallons in order to provide emergency storage in the event of pump or power failure and to assist in maintaining the minimum pumping rate as listed in Section 502.2.(6) Pre-engineered, manufactured packaged pump stations can be utilized in lieu of the composite design described herein, provided the pump meets the minimum capacity requirements of the system and no alterations are made to the pump station other than those specifically authorized by the manufacturer.502.2. Minimum Pumping Rates (Peak Inflow) and Minimum Run Times.(1) For residential systems, the maximum daily flow entering the pump tank shall be based upon one hundred twenty (120) gpd per bedroom. For commercial and other facilities, this value shall be based upon Section 501, Peak Sewage Flow Rate Standard.(2) The minimum pumping rate (peak inflow) for discharges up to fifteen hundred (1500) gpd shall be determined as follows: Maximum Estimated Daily Flow (gpd)____ | Minimum Pumping Rate (peak inflow) (gpm) |
480 and less | 10 |
481 - 720 | 15 |
721 - 1500 | 20 |
(3) The minimum pumping rate (peak inflow) for discharges in excess of fifteen hundred (1500) gpd shall be determined by multiplying the average flow rate (gpm) times a peaking factor of not less than 2.5, where the average flow rate is based upon actual minutes per day of facility operation.(4) The minimum pump run time for all pump systems shall be determined as follows: Minimum Pumping Rate (peak inflow) (gpm)__ | Minimum Pump Run time (min) |
10 - 14 | 3 |
15 - 24 | 4 |
25 and above | 5 |
502.3. Minimum Dosing Volume, Scouring Velocity, and Pump Capacity.(1) The minimum dosing volume (gal) shall be determined by multiplying the minimum pumping rate (gpm) times the minimum pump run time (min).(2) The selected pump(s) must have the capacity to deliver the minimum pumping rate (gpm) at a scouring velocity of at least one (1) ft/sec (effluent) or two (2) ft/sec (raw) against the total dynamic head of the system. This minimum pump capacity (gpm at total feet of dynamic head) shall be specified on the permit to construct.(3) Duplex pumps shall be required when the maximum estimated daily flow is equal to or greater than fifteen hundred (1500) gallons, and each pump shall meet the minimum capacity as stated above.(4) In those cases where the minimum pump capacity or any other system requirements exceed what can be specified through the use of this Standard, the Department shall require the applicant to retain the services of a Registered Professional Engineer licensed in South Carolina.502.4. Force Main, Valves, and Fittings. (1) The force main shall be Schedule 40 PVC, and the diameter shall be sufficient to provide a velocity of at least one (1) ft/sec (effluent) or two (2) ft/sec (raw) using a C Factor of one hundred fifty (150) (effluent) or one hundred forty (140) (raw) at the minimum pumping rate (peak inflow). The force main shall be installed a minimum of eight (8) inches below the ground surface. Fittings and valves shall be of compatible corrosion resistant material.(2) A threaded union, flange, or similar disconnect device shall be provided in each pump discharge line. The pump(s) shall be easily removable at ground surface without requiring entrance into the tank. Valves shall also be readily accessible from the ground surface. Duplex pump systems shall be equipped with a separate pit or box for the placement and operation of valves.(3) A shutoff valve (e.g., gate valve) and a check valve shall be located on the discharge line from each pump. The check valve shall be placed between the pump and the shutoff valve.(4) A three-sixteenths (3/16) inch anti-siphon hole(s) shall be placed between the pump(s) and the check valve(s) when the discharge elevation of the distribution system is below the inlet to the pump tank.(5) In cases where the force main must be installed over undulating terrain, automatic air relief valves shall be placed at high points in the line to prevent air locking.(6) Exposed force mains crossing ditches and bodies of water (e.g., creeks and wetlands) and force mains under driveways and parking areas must be protected by encasing them within a larger diameter pipe that can withstand potential damage (e.g., galvanized pipe, steel pipe, ductile iron). Force mains under driveways and parking areas may also be protected by encasing them within a larger diameter schedule 80 PVC pipe. The protective piping should extend beyond the area of needed protection for at least ten (10) linear feet.(7) The force main effluent shall discharge into a separate discharge box or distribution manifold before entering either a septic tank or a soil wastewater infiltration trench. The flow shall be directed to the bottom of the box through a PVC elbow or into a distribution manifold at an angle of ninety (90) degrees to the septic tank or first wastewater infiltration trench.502.5. Pumps, Control Devices, and Electrical Connections.(1) Pumps shall be listed by Underwriter's Laboratory or an equivalent third-party testing and listing agency and shall be specifically manufactured for use with domestic wastewater.(2) Sealed mercury control floats or similar devices designed for detecting liquid levels in septic tank effluent shall be provided to control pump cycles. A separate level sensing device shall be provided to activate an audible and visible high water alarm. Pump-off levels shall be set to keep the pump submerged at all times.(3) Pump and control circuits shall be provided with manual circuit disconnects within a watertight, corrosion resistant, outside enclosure (NEMA 4X or equivalent) adjacent to the pump tank, securely mounted at least twelve (12) inches above finished grade, unless installed within a weather-tight building. Alarm circuits shall be supplied ahead of any pump overload or short circuit protective devices. The pump(s) shall be manually operable without requiring special tools or entrance into the tank for testing purposes. Conductors shall be conveyed to the disconnect enclosure through water proof, gas proof, and corrosion resistant conduit(s) with no splices or junction boxes provided inside the tank. Wire grips, duct seal, or other suitable material shall be used to seal around wire and wire conduit openings inside the pump tank and disconnect enclosure.(4) For systems requiring duplex pumps, each pump shall operate in a lead-lag sequence and be on an alternating cycle. A control panel shall be provided which shall include short circuit protection for each pump and for the control system, independent disconnects, automatic pump sequencer, hands-off-automatic (H-O-A) switches, run lights, and elapsed time counters for each pump.502.6. Final Inspection and Approval. (1) Before or during final inspection, the property owner or agent shall provide literature, including a pump curve, describing the specific pump installed. The inspector shall evaluate the system in accordance with this Standard, and shall confirm that all items, including the minimum pump capacity specified on the permit to construct, have been satisfied.(2) Prior to final approval, the installer or electrician shall provide the Department with written documentation verifying that pump system electrical connections were made in accordance with all applicable codes. The Department may require testing of the pump system, demonstration of watertight integrity, or any other procedure deemed necessary to confirm the acceptability of the installation.502.7. Raw Sewage Pump Stations.(1) In those cases where it is necessary to pump raw sewage from a residence or facility to an onsite wastewater system, the pump station shall meet all applicable portions of this Standard and R.61-67, Standards for Wastewater Facility Construction.(2) Adherence to the pump manufacturer's recommendations shall also be a major consideration with such systems.S.C. Code Regs. § 61-56.502
Added by State Register Volume 45, Issue No. 05, eff. 5/28/2021.