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Nitrate Loading Study Irerracon Roque Property ■ Victor, California July 6, 2018 ■Terracon Project No. NA187032 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-N, whose maximum drinking water contaminant level (MCL) is 10 mg/L. 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 (https://websoilsurvey.sc.egov.usda.gov), for information regarding soil properties. Based on information obtained from the website, onsite soils consist of Tokay fine sandy loam which consist of well drained soils with 0 to 2 percent slopes. Parent materials consist of alluvium derived from granitic rock. Typical soil profiles consist of 0 to 45 inches of fine sandy loam and 45 to 60 inches of sandy loam. 1.2 Mass Transport Soil Properties Based on a review of the USDA Soil Survey of San Joaquin County California (Issued 1992), Tokay fine sandy loam soils have moderate permeability and slow runoff. Water in-take in irrigated areas is anticipated at 1.5 inches per hour. A tillage pan may form if soil is tilled when wet; however, the pan may be broken up by chiseling or ripping. Tokay fine sandy loam soils have few limitations affecting homesite development. The longer the effluent remains near the surface, the more treatment is enhanced due to natural processes within the soil. Based on the sandy loam soils anticipated near the surface,the potential for effluent to remain near the surface is moderate. 2.0 GROUNDWATER ANALYSIS 2.1 Regional Groundwater Based on a review of the Groundwater Information Center Interactive Map, (https://gis.water.ca.gov) Fall 2017 groundwater depth and elevation maps, groundwater depth lies between approximately 110 and 120 feet bgs. Additional groundwater was not available on the groundwater information center website. Based on a review of the San Joaquin County Flood Control and Water Conservation District Groundwater Report, in 2015 to 2016 Spring&Fall depth to groundwater near the site ranged between approximately 80 feet and 100 feet bgs. The groundwater flow direction and the depth to shallow, unconfined groundwater, if present, would likely vary depending upon seasonal variations in rainfall and other hydrogeological features. Without the benefit of on-site groundwater monitoring wells surveyed to a datum, groundwater depth and flow direction beneath the site cannot be directly ascertained. Responsive ■ Resourceful ■ Reliable 3