ough the side of the tank or through the risers. Be sure that if the wires enter through the risers, a notch or separate hole is provided, SO that the lid will not rest on and damage the wires. Check dosing siphons for air leaks around pipe joints, fittings, and castings by plugging the siphon bell vent, filling the tank with water to the overflow pipe, and looking for air bubbles. Check its operation by unplugging the vent. Operation of the pumped dosing chamber can be checked by filling the chamber to above the high water alarm with the pump power off. The alarm should be activated as the pump is turned on and should stop as the water recedes. The pump should stop at the "pump off" level, but should still be submerged. Operation and Maintenance Little operation and maintenance is required with dosing cham- bers: (1) Follow the inspection and maintenance schedule specified by the pump manufacturer. (2) Have a septic tank pumper pump out the chamber when sludge accumulates on the bottom to the point where it might enter the dosing pump intake. (3) Check the high water alarm from time to time. If the pump or switches require servicing, turn off all power to the chamber before you begin work. If the switching doesn't work, check to make sure the problem isn't simply tangled level controls before turning a wrench or phoning for help. Dosing siphons should be checked periodically to make sure they deliver doses and not a steady trickle. The vent may need cleaning and the bell recharging with air from time to time. Conventional Waste Disposal Systems CONVENTIONAL DRAIN FIELDS Application Where a site evaluation has determined that there is no problem with shallow ground water or bedrock, very loose or very dense soil, slope, or other limiting factor, a drain field comprised of a series of conventional absorption trenches is probably the most cost- effective, simple, reliable, and easily installed method of effluent disposal from the sewage treatment unit. A properly designed, con- structed, and maintained trench dispo