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Nitrate Loading Study Irerracon Valencia Property ■ Ripon, California September 6, 2018 ■ Terracon Project No. NA187044 The Hantzsche and Finnemore approach is "...a conservative (worst case) first approximation of groundwater nitrate-nitrogen concentration resulting from the combined effect of on-site sewage disposal systems and precipitation. This (the equation and approach) is for estimation of long- term effect(i.e., over years)on groundwater quality, and is not intended for prediction of seasonal changes" (Hantzsche and Finnemore, 1992). The method takes into account the development area, soil denitrification factor, rainfall volume, rainfall nitrate concentration,waste effluent quantity, and waste effluent nitrate concentration. The formula, assumptions and calculations used for the analysis are shown in Appendix B. The units of nitrate used in the mass balance equation are nitrate as N. The United States Environmental Protection Agency (EPA) maximum contaminant level (MCL) for nitrate as N in drinking water is 10 milligrams per liter(mg/Q. 1.0 CHEMICAL AND PHYSICAL SOIL PROPERTIES 1.1 Chemical and Physical Soil Properties Terracon reviewed the United States Department of Agriculture (USDA) Natural Resources Conversation Service (NRCS) Web Soil Survey and USDA Soil Survey of San Joaquin County (1992) for information regarding soil properties. Based on information obtained from the USDA sources, site soils consist of three soil types including Delhi loamy sand, Timor loamy sand, and Chuloak coarse sandy loam. Selected physical and chemical properties for the three soil types are listed in the following table. Table 1. Physical and Chemical Properties* Soil Septic Soil Salinity Name I Depth USDA Unified Soil Clay Permeability tank Map (in) Texture Classification (%) (in/hour) reaction (mmho absorption Symbol (pH) s/cm) fields 0-16 loamy sand SM 0-5 6.0-20 6.1-7.8 <2 Delhi/ _....._...._._.........__..............__.._......_._._._...._.._......_.._._._..._._._............._...........---........_............_._._........_._._..........._._..........._._.........--......___........_._....._._......_._._...._.._._._..... Severe; 16-26 loamy sand SM 0-5 6.0-20 6.1-7.8 <2 142 - ._.... ....._..._._._........_._._.._......__._..........._._..._......_._.._._._.....................d_-_ -...._...._._._........_._._..........._.__........_._..........................................._._...._._.__.._.....__........ poor filter 26-60 sand SP-SM 0-5 6.0-20 6.1-7.8 <2 0-14 loamy sand SM 2-10 6.0-20 6.6-7.8 <2 Timor/ -_._._.__......_._._.....__. ...._.__._..........._._._.._-----...__._._._.._....__._.._...---..._.._._.__.__-----.__..._.._----.._.___.._._._......---.....__7.4-8.4________<2 ._._........__._._.._...-----------.....__.__.... Severe; 14-56 loamy sand SM 2-10 6.0-20 7.4-8.4 <2 254 _._..._.._.__...._- __._.._.._..___._....__._.___..._._.__.._...__._....._-__..____._........__.___._.__.._--....._...___._.._.___......_._.._...._._......_.__........__.___....__._._.._..._._-..... poor filter 56-60 cemented --- --- --- --- --- 0-19 coarse SM 0 2.0-6.0 5.6-6.5 <2 sandy20 _.._._._..._. .--._.._. .......................................................-........_............_.__.................._............._._.....------ - -----.. 19-44 sandy clay SC-SN 18 0.2-0.06 6.1-7.3 <2 Severe; Chuloak loam 25 __.._...---._.........__..__....-- ----._._._...................._..._._._........_._._.....__.._... ---..._...._.._._._..._.._._._...._.__._........_._......-----._....-- - --...-- - peres / 127 44-55 sandy loam SM 5-15 2.0-6.0 6.6-7.3 <2 slowly _.---- loa _ --. _ loamy 55-64 coarse SM 5-10 6.0-20 6.6-7.3 <2 sand *Selected USDA physical and chemical properties Responsive ■ Resourceful ■Reliable 3