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. . i <br /> The nitrate-nitrogen concentration;is medius ;"WMIthin the top two ft, and declines significantly down <br /> to 11 ft {19 ppm No3=N down to 2 ppm NO3_N: an approximate tenfold decrease). This decrease in <br /> nitrate-nitrogen concentration suggests a high denitrification potential successively downward.. This <br /> may be attributable to the clay-soil fraction. <br /> Because septic effluent'is compo sed predominately of.ammomurri.(NH4) the pH, along with the <br /> CEC, are significant influences,:on,ammonium molecules. The.pil of the soil is slightly alkaline ' . <br /> which may have.tittle effect on ammonium forts" ation and stability..The".CEC.measures the ability of 1 <br /> the soil to theoretically trap and holdammonium molecules. Cation Exchange Capacities of the soil <br /> samples are comparatively-.high due to the high.clay content. This means there is a high potential for <br /> the retention-of ammonium-molecules for inicrobial uptake, and denitrification potential. This may <br /> be one ofthe reasons the soil profile nitrate=nitrogen_concentrations decrease with depth.. <br /> NLS§3.3,.SSS§5.3. Table 1 below'summarizes the surface and subsurface soil characteristics <br /> tested from the five soilsamples, illustrating the.particularly high clay content,percentages from each <br /> sample: <br /> TABLE 1 - <br /> SOIL PROFILE CHARACTERISTICS AND <br /> ANALI'TICAL`TEST RESULTS <br /> s <br /> SAMPLE LOCATION, = SAND,SiI 1 AND- . SOIL- SOILNITROGEN pH'AND <br /> 'SAMPLIEDEPTH AND CLAY;; CGASSIF.ICATION , -CONTENT--- CATJONEXCHANGE: <br /> (SAMPLE NUMBER) PERCE?\TAGLS .. CAPACITY <br /> FILTER SED <br /> DISPOSAL AREA <br /> 24%, 32%,.43% Clay 19 ppm NO3-N. 8.0 48.2 meq/I OOg <br /> 2.0 FEET.DEPTH - <br /> (2.O FT) <br /> FILTER BED <br /> DISPOSAL AREA 22%,30%,47% Clay 11 ppm NO3-N 8,2 699 meq/100 <br /> 3.5 FEET DEPTH g <br /> (3.5FT) <br /> FILTER BED <br /> DISPOSAL AREA 26%, 34%, 39% C1ay.Loam 6 ppm NO3-N <br /> 5.0 FEET DEPTH 8.6 32.7-.meq/1008 <br /> (5.OFT) = . <br /> I <br /> FILTER BED <br /> DISPOSAL AREA <br /> 7.0 FEET DEPTH 34%0,30%, 35% Clay Loam 9 ppm NO,-N 8.4 34.3 meq/100g <br /> (7.OFT) <br /> FILTER BED <br /> DISPOSAL AREA 50%, 24%,25% Sandy Cay Loam 2 ppm N03448.4 27.0 me /100 <br /> 11,0 FEET DEPTH q g <br /> (11 FT) <br /> Chesney Consulting <br />