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Soil Suitability/ Nitrate Loading Study <br />Lease Property ■ Acampo, California <br />December 17, 2021 Terracon Project No. NA217090 <br />Ircerr on <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, whose maximum drinking water <br />contaminant level (MCL) is 10.0 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 NRCS Web Soil Survey and USDA Soil Survey of San Joaquin <br />County (1992) for information regarding San Joaquin — Urban land complex soils (Section 1.5). <br />Selected physical and chemical properties for the soil types are listed in the following table. <br />Table 7. <br />Physical and Chemical Properties* <br />Soil <br />Soil <br />Name / <br />Depth <br />USDA <br />Unified Soil <br />Clay <br />Permeability <br />Salinity <br />Septic tank <br />reaction <br />Ma <br />in <br />Texture <br />Classification <br />%(in/hour)(pH) <br />absorption fields <br />Symbol <br />San <br />0-16 <br />Loam <br />CL -ML, ML <br />15-25 <br />0.6-2.0 <br />5.6-6.5 <br /><2 <br />Joaquin <br />Clay loam, <br />County — <br />16-26 <br />clay <br />CL <br />35-50 <br /><0.06 <br />6.1-7.8 <br /><2 <br />Severe: cemented <br />Urban <br />pan, peres slowly <br />land <br />Complex <br />26-60 <br />Indurated <br />--- <br />--- <br />--- <br />--- <br />--- <br />(242) <br />*Selected USDA physical and chemical properties <br />Responsive ■ Resourceful ■ Reliable 13 <br />