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Nitrate Loading Study Page 2 Proposed Warehouse 26550 South Banta Road Tracy, California April 15. 2014 CTE Job No 20-2463G 1.0 INTRODUCTION The purpose of this study was to determine the potential nitrate-nitrogen loading to the subject site and down gradient sites resulting from the use of a proposed septic system. The study was performed in general accordance with requirements of San Joaquin County Development Title Chapter 9-1105, Section 9-1105.2 and San Joaquin County Environmental Health "Nitrate Loading Study Requirements Checklist" (EHD 26-02, 7/14/03). The following report includes information regarding the chemical and physical properties of the soil, discussion of groundwater, sources and calculated impact of nitrate-nitrogen to groundwater, a discussion of nitrate-nitrogen loading results relative to the proposed method of wastewater disposal, and conclusions and recommendations based on the information contained in the report. 2.0 CHEMICAL AND PHYSICAL PROPERTIES OF SOIL According to the United State Department of Agriculture (USDA, Soil Survey of San Joaquin County, California, dated October 1992) the subject site is underlain by Capay series soil. Published USDA mapping documents describe the Capay series as consisting of"moderately well drained soils on interfan basins from mixed rock sources. These soils are described as very deep with slope ranges 0-2 percent. Soils of the Capay series are fine, montmorillonitic, thermic, Typic Chromoxererts. The Capay clay is indicated as having a rate of water intake in irrigated areas of 0.1 inch per hour(approximately 590 min/inch). Soils encountered during our study (see our "Percolation Testing and Soil Suitability Study" for the site) are described as stiff to medium stiff, medium to low plastic clays, silty clay, and clayey silts to the maximum explored depth of about 25-ft. Soil boring logs are included in Appendix A. The field study also included a percolation test, witnessed by ,staff from the San Joaquin Environmental Health Department (SJEHD). Due to the clayey nature of the soil, percolation testing was performed after a 24 hour pre-saturati period was completed. The results of the percolation testing indicated a percolation rate o 480 min/inch. The percolation test rate sheet signed by a representative from the SJEHD is attached as Appendix B. The results from the field study are considered consistent with the soils description in the referenced USDA Soil Survey. Based on information on the State Water Resources Control Board's "Geotracker" website, a clean-up program occurred in 1998 and 1998 on the Olin Chlor Alkali Products property (26700 Banta Road) adjacent to and southwest of the subject site. Olin Chlor Alkali Products produces sodium hypochlorite (liquid bleach) from chlorine. The source of the contamination has been linked to wastewater pond 1 and 2, constructed prior to 1980, located along the northeastern boundary of the site. In October 1998,pond sediment and the underlying liners were removed and disposed of at an off site location. Beginning on August 9, 1999, soils beneath the former liners for Ponds 1 and 2 were excavated and remaining soil tested for soluble sodium and soluble chloride. Currently the status of the site is"Open-Verification Monitoring"