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lrerracon Soil Suitability / Nitrate Loading Study <br />Buddhist Temple Proposed Dormitory a Stockton, California <br />July 11, 2019 • Terracon Project No. NA177056 <br />convenient and simplified method to estimate long-term groundwater nitrate impacts on an area- <br />wide basis. <br />Hantzsche and Finnemore found that over a long period of time, water quality in the upper <br />saturated groundwater zone closely approximates the quality of percolating recharge waters. <br />They believe that their method is a good planning tool and provides useful information to planners <br />and local officials but with some real limitations. In their article published in Ground Water, <br />Hantzsche and Finnemore mention that "...the equation ignores dispersion, lateral flow, and <br />mixing with groundwater flow from up-gradient areas. These processes would generally <br />contribute to additional reduction of nitrate-nitrogen concentrations in groundwater to the extent <br />that the nitrate-nitrogen concentration of groundwater flow from up-gradient areas is lower." <br />The Hantzsche and Finnemore approach is "...a conservative (worst case) first approximation of <br />groundwater nitrate-nitrogen concentration resulting from the combined effect of on-site sewage <br />disposal systems and precipitation. This (the equation and approach) is for estimation of long- <br />term effect (i.e., over years) on groundwater quality, and is not intended for prediction of seasonal <br />changes" (Hantzsche and Finnemore, 1992). <br />The method takes into account the development area, soil denitrification factor, rainfall volume, <br />rainfall nitrate concentration, waste effluent quantity, and waste effluent nitrate concentration. The <br />formula, assumptions and calculations used for the analysis are shown in Appendix F. The units <br />of nitrate used in the mass balance equation are nitrate-N, of which the maximum drinking water <br />contaminant level (MCL) is 10 mg/L. <br />2.1 Chemical and Physical Properties of Soil <br />2.1.1 Chemical and Physical Soil Properties <br />Terracon reviewed the USDA Soil Survey of San Joaquin County (1992) for information regarding <br />soil properties. Based on information obtained from the USDA sources, site soils consist of <br />Devries sandy loam. Refer to Sections 1.1 and 2.12 for further discussion of the soils. Selected <br />physical and chemical properties are listed in the following table. <br />Table 7. <br />Physical and Chemical Properties* <br />Soil <br />Name / <br />Map <br />Symbol <br />Depth <br />(in) <br />USDA <br />Texture <br />Unified Soil <br />Classification <br />Clay <br />(%) <br />Permeability <br />(in/hour) <br />Soil <br />reaction <br />(pH) <br />Salinity <br />(mmhos/ <br />cm) <br />Septic tank absorption <br />fields <br />Devries <br />sandy <br />loam / <br />149 <br />0-13 Sandy loam <br />Sandy <br />loam, fine <br />sandy loam <br />indurated <br />SM 7-18 2.0-6.0 6.6-8.4 <2 <br />Severe; <br />cemented <br />pan <br />13-28 SM 7-18 <br />2.0-6.0 <br />6.6-8.4 <br />----- <br /><2 <br />- 28-80 ---- -- -- -- <br />Selected USDA physical and chemical properties <br />Responsive • Resourceful • Reliable 14