 that's about the amount of effluent which would be pumped out of that hole when the pump is running. Discharge rate = 3.2 gal/min + 2 gal/min = 5.2 gal per min. The pump dealer will select a pump which is designed to deliver 5 gal per min at a total head of 10 ft with a reasonably high efficiency. Figure 4.8 illustrates a pump curve for a specific pump which would be suitable for this application. This pump is designed to deliver a 5 gal per min flow at a 10 ft head with near maximum efficiency. If the intersection of the required flow rate and head lines falls above the ONSITE WASTEWATER DISPOSAL Flow (gpm) Figure 4.8 Typical pump curve. pump performance curve, the pump would be too small for the job. If we wanted 1 gal per min at 15 ft, this pump would be too inefficient. Materials 1. dosing chamber (septic tank, large diameter pipe, cistern, etc.) 2. water proofing 3. risers for access 4. submersible pump or dosing siphon 5. switch for pump "off-on" 6. high water alarm switch and alarm (light or buzzer) Note: Items 5 and 6 are often sold as a single unit electrical conduit, inlet and outlet pipe and fitting, PVC glue, mor- tar or other material for sealer, nylon rope, 2 concrete blocks, water proofing WASTE PROCESS Construction The dosing chamber may be built directly onto the outlet end of the septic tank or may be a separate unit. In either case, the bottom of the dosing chamber should rest on a stable soil SO that shifting will not break the connection between the septic tank and the cham- ber. This connecting pipe should slope at no less than 0.25 inch per foot. Note that dosing siphons in particular must be installed on a level base in order to function as designed. Dosing chambers should be waterproofed in the same way as septic tanks. Where there is a possibility of freezing, the effluent pipe should have a 0.25-in. hole in the pipe just inside the chamber (as shown in Figure 4.6) to drain the effluent pipe after each dose. This hole should also be drilled if there is any chance of the effluent in the 