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r y <br /> r <br /> r <br /> sformations. The significance of cation exchange becomes important when the chemistry of <br /> tic effluent is analyzed. Nitrogen in septic tank effluent consists of approximately 75%N in the <br /> monium ion(NH4') form and 25%N in the organic form. If the ammonium ion is bound and <br /> eventually immobilized, nitrification cannot occur. <br /> The results of the soil nitrate-nitrogen concentrations were interesting. The soil sample from the <br /> future leachfield at the 42 inches in depth tested at 10 ppm NO3-N. Considering that this soil has <br /> been farmed in apricots for many years, a higher indigenous NO3-N content would have been <br />�. expected. <br /> 2.,, SUBSURFACEVSOILOIHYDRAULIC CONDUCTIVITY <br /> In addition to the conventional perc tests described below, hydraulic conductivity data of the <br /> 4 shallow soils from zero to 18 inches in depth was obtained with the test results illustrated on the <br /> PERCOLATION TEST DATA. After four hours of testing, it was determined that the shallow soils <br /> absorb 3,850 cc/hr (2,000 + 1,850 = 3,850 cc) of water. This is equivalent to 0.01695 gal/min or <br /> 24.4 gallons/day. Since the internal area of an 18-inch deep x 4.5 inch dia. boring is 270 in' or 1.9 <br /> ft', the application rate for the surface soils is theoretically 12.8 gallons/ft'/day. <br /> C. PERCOLATION TEST RESULTS <br /> The percolation test was conducted on May 13, 2003 under U.S.E.P.A. and San Joaquin County <br /> Environmental Health guidelines. Since the soil type at typical leachline depth of 42 inches is a <br /> loam soil, the test period was four hours in duration. As indicated on the attached PERCOLATION <br /> TEST DATA, the perc rate for the test boring reveals a comparatively rapid perc rate considering <br /> the loam soil. This phenomenon is regularly observed in Tracy area soils and may be attributed to <br /> the clay lattice structure in this area giving the clay soil a higher porosity. The test results are <br /> . summarized below: <br /> l <br /> aft?;eeaee.�ti-: �Vr ✓ , „� 'tdesets°rs-t! �ts . .aazae € @➢s[ �i �t�.rL; a i'�?&�=s z",� �� <br /> Pte, <br /> PERCOLATION AND �3"YDR 'ULICV0L. NDCJCTIVIT ;TESmT REEL LTS <br />� {tK...z re:4 :.'r:;e 0 �ni�$. •"l'w�t:31 da"n...,,.,3 �i'�rt=C F4d'€ -^ A✓s.cz£.?l�l <br /> SHALLOW PERC TEST PERC RATE IN HYD.GOND.TEST GALLONS/SO FTIDAY <br /> MIN/INCH <br /> Leachfield Area(42 in. Deep) 11.9 minlin Leachfield Area (18 in. Deep) 12.8 gals/ftZ/day <br /> Page -3- <br /> Chesney Consulting <br />