AL The flow in each of the two legs of the lateral is half of the total flow, or 13 gal per min. At that flow rate, the head loss is 2.42 ft per 100 ft of 1.25-in. PVC. The loss then is 99 ft X 2.42 ft of head = 2.4 ft of head 100 ft Again, we want 3 ft of hydraulic head pushing the effluent out the holes, SO the total head needed is 11.5 ft for elevation plus 1.2 ft for supply pipe friction, plus 2.4 ft for lateral friction, plus 3.0 ft for head at the holes or 18.1 ft of total head. We must select a pump which will deliver 26 gal per min at 18.1 ft of head. Because the mound will be higher than the dosing chamber and the supply pipe will be buried below frost line, there is no need for an antisiphon hole and the associated 2 gal per min capacity for the pump. The volume per dose would be a minimum of 10 times the volume of the lateral pipes: 10 X 0.0408 X (1 in.)2 X 99 ft = 40 gal This would be a dosing frequency of 300 gal 40 gal = 7.5 times per day More resting time between doses would be better in a silty loam soil, SO let's increase the volume per dose to 100 gal. Then the dosing frequency is reduced to three times per day. Now, if we can just build it right, it should work. Materials 1. Septic tank. 2. Dosing chamber with pump and controls. 3. PVC pipe (schedule 40 or thin wall) for supply line, manifold, and laterals, plus tees, elbows, and reducers as needed. Forty-five degree elbows for turn-ups. 4. PVC or bronze gate or ball valve for final pressure adjustment (optional). 5. Mound fill material: unwashed medium to coarse sand, sandy loam, or loamy sand. To calculate the volume needed, use the following formula: CONVENTIONAL SYSTEM MODIFICATIONS top + base X height X length = volume For example, a mound 3 ft high with a 10-ft wide top and a 30-ft base that is 75-ft wide would take 10 ft + 30 ft 3 ft X 75 ft = 4500 cubic ft of fill Dividing 4500 ft3 by 27 gives us 167 yd3 of fill needed for the mound. 6. Topsoil cover. The volume of topsoil cover needed is about one- third to one-fourth of the fill volum