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Total Suspended Solids (TSS) is the material retained on a standard glass-fiber filter disk. Suspended solids can be categorized as volatile or fixed suspended solids. TSS can create and enhance the biomat formation between the soil and effluent interface, thus restricting infiltration. The biomat, also referred to as a"clogging mat," is a biological, slimy substance which forms on the soil-effluent interface over time. This mat is composed mostly of aerobic and anaerobic bacteria and bacterial products consisting of polyuronides and polysaccharides. Total Nitrogen is the summation ofammonia-nitrogen (NH4) and organic nitrogen (proteins, amino acids, enzymes). Since the septic tank is predominately anaerobic, virtually no nitrate exists in the effluent. If nitrate existed in septic tank effluent, this would also be added to arrive at Total Nitrogen. To quantify the anticipated nitrate loading from the built-out project, an effluent sample was obtained from the on-site septic tank at the west end of the property. The sample was taken to A & L labs in Modesto, California. The test results were unusual in that nitrate was found in the effluent at 4 ppm. A second sample was retrieved from the tank for a second analysis. Due to the critical nature of this analysis, a split identical sample was also taken to FGL Labs in Stockton, California. The FGL analysis indicated a lower ammonia-nitrogen concentration. However, .the FGL test results are also suspect since they claim that the Kjeldahl Nitrogen was 90 mg/L, the Ammonia Nitrogen was 81,but the Organic Nitrogen was Non-Detect (ND). Kjeldahl Nitrogen is the total of the organic and ammonia nitrogen. Therefore, the Organic Nitrogen should have been 19 mg/L. (19 mg/L+ 81 mg/L=90 mg/L Kjeldahl Nitrogen). The test results are illustrated in the Table below. In addition, concentrations of weak, medium and strong strength wastewaters have also been presented for comparison purposes from Wastewater EEn ineerimz, 3"Ed., in the three columns on the right. First Analysis by Second Analysis by FG.L Analysis Wastewater Engineering ANALYTE A&L Labs ZA&L Labs Metcalf&Eddy 3'Ed (Concentrations in mg/L) Weak Medium Strong Ammonia Nitrogen(NHa N) 130.0 mg/L 130.0 mg/L 81 mg/L 12 25 50 Organic Nitrogen 5.5 mg/L 5.5 mg/L 19 mg/L(???) 8 15 35 Nitrate 4 mg/L BDL ND 20 40 85 Total Nitrogen 139.5 mg/L 135.5 mg/L 90 mg/L Total Suspended Solids 72 mg/L 72 mg/L --- 100 220 350 (TSS) Biochemical Oxygen 38 mg/L 3 mg/L ---- 110 220 400 Demand(BOD,) pH 7.7 7.7 ---- nla n/a n/a Total Alkalinity 1020 mg/L 1020 mg/L 910 mg/L 50 100 200 Consequently, since a"true" or"accurate" analysis for Total Nitrogen is unknown for the effluent testing, the Total Nitrogen concentrations have been averaged to obtain a concentration for use in the Nitrate Loading calculations. This figure is 135.5 + 90= 225.5 - 2 = 113 mg/L Total Nitrogen. 10 Chesney Consulting