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The following describes the operational design: The OWTS design starts with a 1,600 gallon standard precast septic tank that is set with the inlet invert elevation 18.75 inches below existing grade. This invert elevation is based on the septic tank installed 100 ft from the proposed domestic well location, and 70 ft from the modular home. The 1,600 gallon tank will allow sufficient hydraulic residence time (HRT) and decrease raw wastewater nitrogen concentrations by 20%or more. (See Oakley). Effluent will then gravity flow from the tank to a Polylok® 10 Hole, 24" Rhino Baffled Distribution Box,with a 24" riser and a 24" riser cover, set to finished grade. Each of the 9 D-box outlets are to be fitted with 4" Tuf-Tite® Speed Levelers to ensure equal distribution of effluent flowing from the nine outlets. Effluent will then gravity flow into Infiltrator(t EZFIow® engineered geosynthetic aggregate, illustrated in Appendix C. Supplemental drainage pipe has been incorporated into the design of the EZFIow modules. The design plans illustrate nine rows of 1 ft dia. EZFIow tubes, each row composed of three - 10 ft sections and one 5 ft section for a total length of 35 ft. The ends shall be capped to force approximate equal distribution of effluent. EZFIow tubes are to be placed 2.0 ft from the filter bed edge, and spaced 1.5 ft apart in the 25-ft N-S x 35 ft E-W= 875 sf filter bed. Backfill with excavated soil to allow grass-lawn root structures to grow around and under the length of each tube to uptake nitrogen, as illustrated on the design plans. The two primary design factors for the mitigation of nitrate loading from this project are: 1.) How much domestic irrigation water in combination with effluent disposal water must be supplied to maintain lawn vigor, correlated with evapotranspiration, and 2.) How much nitrogen can be assimilated by the Fescue lawn grass, which must be planted over the filter bed. The following volumes are calculated: WATER DEMAND FOR FESCUE LAWN GRASS P=Precipitation for the Ripon Area(gals/yr) I=Domestic Lawn Irrigation(gals/yr) E=Effluent Disposal Volume(gals/yr) ETo=Reference Evapotranspiration(gals/yr) Values and Assumptions: P=Precipitation in this locale is 12.32 in/yr, determined by CIMIS Data presented in the Petralogix Report= 12.32 in/yr x 27,152 gals/ac-in x 875 sf filter bed(0.0201 ac)=6,723 gals/yr. I=The fine sandy loam soil structure under the proposed filter bed can hold approximately 1.5 inches of available water per foot of soil at field capacity(See Brady and Oster). Rooting depth of Fescue lawn grass,which must be planted,can easily reach four-ft. Consequently, 6.0 inches of water(1.5"/ft x 4 ft= 6")within this soil profile depth must be available from a combination of effluent and domestic irrigation. The lawn growing season when irrigation is needed is primarily February through October. At an average water-use rate of 0.25 inches of water applied daily for this 214 day period, 53.5 inches of water will have been applied,which corresponds with the daily,monthly and yearly ETo: Page -2- Chesney Consulting