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July 2, 2007 <br /> NOA Project Number: E06122A <br /> Page 4 <br /> density of 10 pounds per cubic foot for sawdust/woodchips and including a factor of 4 to account <br /> of uneven mixing and non-cellulose impurities of wood, approximately 12 yards of <br /> sawdust/woodehips will be required to be mixed into the sand for placement into the trenches. <br /> The ratio is approximately 17 percent wood product to coarse sand by volume. Please refer to the <br /> plans for dimensions of the disposal trench. <br /> Septic Tank Volume <br /> Due to the concerns of potential high use of the facility by the EHD,the septic tank volumes <br /> were increase to an overall retention ratio of 7 with a primary tanks having a retention ratio of 5. <br /> Generally a primary tank ratio of 3 to 5 is satisfactory. <br /> Please refer to the attached plans for additional septic tank details and layout. <br /> Pressure dosing System <br /> Pressure dosing is proposed within a drain-field chamber for uniform application. The chamber <br /> and carbon filter vents will promote an aerobic environment for nitrification of the dosed <br /> effluent. Within the sandy bottom of the trench, anaerobic processes, supplemented by cellulose, <br /> will enhance denitrification. The clayey soils will slow the percolation of the effluent allowing <br /> some moisture to accumulate on the bottom of the trench. <br /> A duplex pumping system is required by the EHD for conunercial septic systems. We <br /> recommend an Orenco P3005 (30 gpm)pump package with time dosing panel. Please refer to <br /> drawing for additional details and the pump curve attachment for the pump selection information. <br /> Monitoring <br /> The San Joaquin County EHD requires initial monitoring on all commercial engineered septic <br /> systems for nitrate reduction. This system will require twelve (12) monitoring visits which may <br /> occur over one year. Several monitoring parameters will be required: <br /> —Note the water meter reading. <br /> —Inspect the overall septic system condition. <br /> —Measure fluid level in five (5) 2-inch dia. monitoring port <br /> — Draw fluid in four monitoring ports for trenches 1 to 4 to make one (1) composite and <br /> test for nitrate. <br /> --Draw fluid in one monitoring port in trench five (5) and test for nitrate. <br /> —Extract effluent from two (2) lysimeter ports to make one composite sample from <br /> trenches 1 to 4 and test for nitrate and ammonia. <br />