ners inside. The liner rests on 1 ft of gravel in the pit bottom and consists of a circular wall of brick or block laid dry (without mortar). The liner should have staggered joints, and should come within about 6 in. of the side of the pit. The 6-in. space is filled with 0.75- to 2.5-in. gravel. The inlet pipe may enter through the side or through the pit cover. Covers are normally of reinforced concrete about 5 to 6 in. thick and extend 6 to 12 in. beyond the edge of the pit. The covers do not rest on the liner but on the soil around the pit. In some areas, premanufactured wood, metal, or concrete liners are available, which may end up being less expensive than having a liner built in place. They are certainly easier and safer to install, and are a "must" for small diameter pits and for pits dug in loose soil. Weep holes must be cut in precast concrete rings if none are present. You want a seepage pit, not a swimming pool for gophers. Materials 1. Brick, block, or precast liner. For a liner 10 ft high and 6 ft in diameter, about 255 blocks 8" X 8" X 16" are required. 2. Gravel, 0.75 to 2.5 in. For a 6 ft diameter, 10 ft high seepage pit, about 4.25 yd3 are required. 3. Precast or other reinforced concrete slab lid with 9 in. inspection hole. For a 6-ft diameter pit, an 8-ft diameter lid is required. This lid would use about a yard of concrete and about 9 20-ft lengths of #4 steel reinforcing rod. Appropriate lengths of solid 4-in. PVC pipe with elbow for inlet, and overflow connections where multiple pits are used. 5. Bituminous waterproofing as for septic tank. Construction A round hole should be dug, since the circular shape is depended on for liner stability. Square holes won't work because even pres- sure from the gravel pushing on the outside of the liner is needed. ONSITE WASTEWATER DISPOSAL The hole should not be dug in wet weather, and if there are any signs of smearing of the soil on the pit walls or bottom, the smeared areas should be scraped and the scrapings removed. Smearing is the most common cause