 X 3.67 = 14.6 ft = 14 ft 8 in. The effective length of the mound is 50 ft (the length of the trench) and the width is 5 ft (the trench width) plus 14.7 ft (the downhill mound side) or 19.7 ft. The total absorption area available under the mound is 19.7 ft X 50 ft = 985 ft2 The natural soil infiltration rate is 5 90 = 0.53 gpd/ft2 therefore, the minimum absorption area required is CONVENTIONAL SYSTEM MODIFICATIONS 300 gpd 0.53 gpd/ft2 = ft2 There will be sufficient area available under the mound to accept the design flow. The distribution system is the last factor to be considered in mound design. The distribution system consists of a dosing chamber, a supply line, a manifold (if needed), and the distribution laterals. Design of the dosing chamber, except for pump sizing, is dis- cussed in Chapter 4. Generally, a pump capable of delivering at least 25 to 50 gal per min at the distribution pipe is sufficient for mound distribution systems. For systems serving houses with four or more bedrooms, a flow of 30 to 90 or more gal per min is usually required, depending on the distribution system design. The supply line is generally a 2-in. PVC pipe connecting the dosing pump to the distribution system manifold. The manifold is generally a 2-in. PVC pipe which feeds two or more laterals (there is no manifold with only one lateral line). The laterals are generally 1- to 2- in. PVC pipe where there is more than one lateral. They should be connected to the manifold in an "H" configuration SO that the dis- tance from the supply line to the ends of the laterals is the minimum possible. In beds, an "O" or looped configuration can be used (Fig- ure 5.5). Where the beds are very wide, more laterals can be inserted through the interior of the "O." Lateral length is simply trench length minus 1 ft. The laterals should end 6 in. short of either end of the trench SO that effluent will not bypass the gravel and seep out the mound sides. Laterals should be no longer than 50 ft from manifold to end. Where there is more than one lateral 