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FEMuentt Line Under Roadway - Calculations nning from the septic tank to the D-Box must cross under an unpaved driveway. ill support light traffic (cars and pickup trucks) as well as heavy duty class 8 quently,pressures exerted by these large trucks on this tight line must be known. The Class 8 truck load on piping buried under flexible pavement or under an unpaved road is given in the equation below: P,=RF CP bD Where: P,=Truck load in pounds per square inch R=Reduction factor. This factor accounts for the fact that part of the pipe directly below the wheels receives full intensity,but is aided by adjacent portions of the pipe that also carries a load. Taken to be 1.0 F=Impact factor of 1.5 C=Surface load factor.Taken to be 0.1001 P=Wheel load. 16,000 lbs.for single H-20 truck wheel b= Effective pipe length of 36 inches D=Outside diameter of pipe in inches=4.50" Therefore, it is projected that truck wheel loading on the ABS pipe with 2 ft of soil cover to be: P,_(1.0 x 1.5)x 0.1001 x 16,000= 14.8 psi 36 x 4.50 ABS Schedule 80 (2112)must be installed both from the restroom to the tank, and from the tank to the D-Box, as depicted on the Plans. Primary and 100% Replacement Effluent Disposal Area The filter bed area is calculated in the procedure described in Section 8.7 of the San Joaquin County Sewage Standards and EHD Document 42-01-004: Calculation Requirements for Commercial Septic Systems: Base Tank Capacity(BTC)= 1,200 gals Lineal Feet of Leachline (LFLL) = 1,200 BTC + 32 ADF x 0.25 Clay SF = 308 LFLL. The primary leachfield is to consist of two 60 ft Infiltrator Chamber leachlines and two - 48" dia. seepage pits, for an equivalent LFLL of: 60 +60+90+ 90 =300 LFLL. The 100%reserve/replacement area is denoted on the full-size plans and is located directly to the north of the primary disposal area. As noted, the septic system replacement consists of a 30 ft Infiltrator Chamber leachline and three - 48" dia. seepage pits, or an equivalent LFLL of: 30+ 90 +90+90=300. Due to area constraints, only a 30 ft chambered leachline and three -48" dia. seepage pits can be installed. The seepage pits are oriented in a serial configuration whereby as the Infiltrator Chambers become filled with effluent, the liquid gravity flows to the first seepage pit. this pit becomes saturated and fills, effluent flows to the middle pit, and then ultimately to the thrd i or last pit. The scientific literature references serial configurations preferable to equal distribution or parallel effluent distribution. Page -4- Chesney Consulting