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Values and Assumptions: I=450 gals ADF x 365 d/yr= 164,250 gals=total WW/yr=21,959 cu ft =4.42 in/yr �I 1.37 Ac x 43,560 sq ft/Ac x (1 ft/12 in) Nw= (15 grams N/person-dav)(1000 mg/gram)(20%N reduction in 1600 gal septic tank)=42 mg/L Total N (75 gal/person-day)(3.78 Ugal) d = Assume 33% from the fine-grained loam fraction of the soil,as evidenced by soil test results: 3 ppm reduced to 2 ppm=33%decrease. R = 2.21 in/yr. from Table 3 above. Nb= Assumed to be 0.1 ppm NO3-N .—v 4.42 in/yr(42 mg N/L)(1 -0.33)+(2.21 in/yr x 0.1 mg/L) Nr = (4.42 in/yr+2.21 in/yr) Nr = 18.8 ppm as nitrate-nitrogen (NO3-N) or 83.6 ppm as nitrate(NO3) IV. O.W.T.S. DESIGN - OPERATIONAL COMPONENTS AND PARAMETERS To mitigate the excessive nitrate loading (as calculated) from the proposed OWTS, the following design parameters are presented. Although it is debatable as to whether any on-site system within San Joaquin County falls under Tier 3 - Impaired Areas, Section 10.9 from Tier 3 of the State Water Board OWTS Policy is referenced. The EHD follows the directive from this Section"to meet a 50% reduction in total nitrogen when comparing the 30-day average influent to the 30-day average effluent." My design also incorporates Section 10.9.2 regarding disposal components "used to enhance vegetative nitrogen uptake, [with] the dispersal system having at least six (6) inches soil cover." The design also incorporates a monitoring program, as proposed in the next Section. The following describes the operational design: The OWTS design starts with a 1,600 gallon standard precast septic tank. Although a 1,200 gallon tank is specified under the EHD OWTS standard requirements for a 3-bedroom house, the tank size is being upgraded to a 1,600 gallon tank size to increase hydraulic residence time (HRT) and to decrease raw wastewater nitrogen concentrations by 20% (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® EZFIow®engineered geosynthetic aggregate, illustrated in Appendix J. The design plans illustrate nine rows of EZflow tubes, each row composed of three - 10 ft sections for a total length of 30 ft. The ends shall be capped to force approximate equal distribution of effluent. EZFIow tubes are to be placed 2.0 ft from filter bed edge, and spaced 1.5 ft apart. 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. t Page -8- Chesney Consulting