er the mound must be plowed to a depth of 7 or 8 in. By plowing the surface, when the sand fill is applied, it will mix with the broken-up natural soil SO there is no sharp barrier to the absorp- tion of effluent. In sandy soils, rototilling or discing is usually suffi- cient. The furrows should follow natural contours and should be plowed SO that the soil is thrown upslope. Chisel teeth on a backhoe bucket could be used to break up the soil, but there must not be even a hint of smearing. This step should be planned SO that the fill can be added before it rains on the plowed soil. After plowing, no vehicles should be driven over the area. Now repair the supply pipe that you cut with the plow bottom. With a backhoe or front end loader (or shovel), place the first layer of sand over the plowed area. Work from the uphill edge where possible to minimize traffic on the downhill slope. A small crawler- type tractor is ideal for spreading sand and contouring the sides. A snow plow attachment on a garden tiller or tractor would work well If the native soil is dense and in clods, it would be wise to till this first layer of sand into the soil beneath. You may find it useful at this point to place a few slats in the ground under where the trenches or bed will be, SO that their tops are at the level of the desired fill. Also, tie the supply pipe to a stake SO it doesn't get buried. Continue to add fill until the final fill height and side slope are reached. Do not-compact the fill. Uneven compaction can promote lateral movement of the effluent and result in side-hill seepage. Normally, trenches are excavated into the fill, while beds will have sides placed around a level top. Trenches can be cut with the light CONVENTIONAL SYSTEM MODIFICATIONS Figure 6.11 Laterals located below manifold. tractor or dug by hand. In any case, hand leveling of the bottom will be necessary. Check your work at this point for correct dimensions and level absorption surface. Tamp the soil tightly around where the supply pipe protrudes from the fil