SU0002185 SSNL - Laserfiche WebLink

Home Browse Search

E September 24, 1.999 Job Number.'S99244 Page 6 identified between 7 LU44-kt-depth. After evaluation, the exploratory boring was backfilled to the surface. A percolation test was located about 5 feet south of the exploratory boring and drilled to a depth of 10.5 feet in a fine to medium sand. A 2 inch PVC pipe with slots on the bottom was P _ r he ercolation test. Several inches of ea gravel was placed in the ed in the boring for t P install g percolation bottom of the hole,the casing was installed, and several feet of pea gravel was backfilled in the as conducted on September 14 cro rdance:with the annular space. The percolation test w p , 1949 in a requirements of San Joaquin County Environmental Health Division and was observed by Mr. t office. The result of the percolation test indicates a satisfactory peculation Johnny Yoakum of that P - Ir rate of for the sandy soils located at about 10.5 feet in depth(Plate 6:and Plate 7). VII. NITRATE LOADING STUDY A buildup of nitrates in the upper ground-water zones can cause a temporary blood disorder in infants called methemoglobinemia(blue baby)_ Serious and occasionally fatal poisonings in infants have occurred following the ingestion of water containing nitrate concentrations greater than 10 mg/l nitrate as N or 45 mg/l nitrate as N0.. The nitrate loading analysis estimates the concentration of nitrate-N of the septic effluent water after denitrification before mixing combined with rano g with ground water. The method is based on a simple mass balance formula which takes into account soil denitrification,rain fall, and the proposed waste effluent quantity and nitrate level. Assumptions and calculations for the analysis are contained on Worksheets No. 1 and 2 (Plate 9 and Plate 10). The units of nitrate in used in the mass balance equation is nitrate-N with a maximum drinking water contaminate level of 10 mg/l. Denitrification is the biological process in the soil whereby certain bacteria utilize.the oxygen in the nitrate(NO3) and release nitrogen gas(N) to the atmosphere. Denitrification is expressed as a percentage, and the normally accepted range is 10%to 25% _ Soils with higher. clay content, moist soil conditions,and organic material denitrify about 25% or more but soils with higher sand content and fast peculation rates are estimated to denitrify about 10%. Due to the presence of dark gray clay material located in the first three(3) feet, we estimate the denitrification factor be about 25 %. In our approach to estimate the nitrate concentration,we used the following information for our calculation. Ol�dOy � r O � T t+t o c f