 of seepage pit failures and is the reason that seepage pits are not recommended for tight soils. Bucket augers, clamshells, orange peels, and backhoes (with extreme difficulty) can be used to dig the pit. Buckets with dull cutting teeth and buckets with a top diameter larger than the bottom diameter are major causes of smearing. Holes drilled at an angle are likely to have a smeared side. The best holes are dug with a bucket smaller than the final hole diameter. Trenches for the inlet and outlet (if any) should be dug at this time. Keep a 0.25 in. per ft (2%) slope as a minimum. Then place 1 ft of 0.75 to 1.5-in. gravel in the pit to protect the soil at the bottom of the pit and to serve as a base for the liner. Smooth the gravel. Note that a firm foundation is necessary to prevent the liner from collaps- ing or settling, resulting in the rearrangement of the inlet and outlet piping. Next, lower the precast liner into place, or begin liner construction. It is a good idea to coat the concrete block and concrete lid with a bituminous waterproofing material to protect against corrosive liq- uid and gases. Dipping the block into a bucket of this waterproofing material is worth the cost and effort if you want the pit to last more than 10 to 15 years. Bed the first course of block radially (Figure 5.15), about 6 in. into the gravel (2 in. for brick). Lay the second course of block length~ wise to the circumference, ends separated by the thickness of a credit card. The third and remaining courses are laid the same way, with staggered joints for each course. The Uniform Plumbing Code requires blocks longer than 12 in. to have matching beveled corners where the ends meet. These surfaces are supposed to be scored to permit seepage. This tedium should not be necessary with liners over about 5 to 6 ft in diameter. Smaller diameter liners should use smaller block or brick. If a bricking machine is not available, the brick or block liner must be placed by hand. But never climb into a hole which could cave in on you. Work only