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Nitrate Loading Study Page 4 Proposed Warehouse 26550 South Banta Road Tracy, California April 15.2014 CTE Job No 20-2463G The two sites up gradient include an open land disposal site at the All-Pure Chemical Company and verification monitoring (as described above) at Olin Chlor Alkali Products, both located are at 26700 Banta Road. The other open site is a clean-up located down gradient at the Tracy Defense Distribution (Area 3). More information regarding nearby sites is included in Appendix C. Olin Chlor Alkali Products manufactures sodium hypochlorite (liquid bleach) which is produced from chlorine. The site has been used to manufacture and package bleach since 1975, and previously had 6 ponds. Four were wastewater ponds for manufacturing process liquid. The site previously had a sulfuric acid repackaging line and a truck maintenance shop. The Small Wastewater Pond was 4 feet wide, 4 feet long, 3 feet deep, and lined. It was reportedly used to collect runoff from the wash rack where empty chlorine containers were cleaned. In 1994 sediment was collected from the pond and disposed off site, and the pond was closed by backfilling it with native soil. Pond I and Pond 2, constructed in 1977, were located along the northeastern boundary of the Olin Alkali site. They were approximately 60 feet wide, 100 feet long, 4 feet deep, and lined with a PVC liner. Ponds 1 and 2 were used to store process wastewater; occasionally they were used to store cleanup spills within the process area of the plant. In October 1998, pond sediment and the liners were removed and disposed off site. Approximately 570 tons of materials were removed. Beginning on August 9, 1999, soil beneath the former liners for Ponds 1 and 2 was excavated and remaining soil tested for soluble sodium and soluble chloride. Approximately 3,200 cubic yards of soil were excavated and disposed off site. The Regional Water Quality Control Board (RWQCB) approved the Closure Report in a letter dated February 24, 2000. Currently, groundwater quality, elevation, and, gradient is monitored by twelve monitoring wells placed at the site and in the vicinity. Selected pages (from Quarterly Monitoring Well Reports, Santec, 2014, et. al.) considered pertinent to nitrate loading are included in Appendix D. Between 1948 and 1957, the Olin Alkali site was used for alfalfa dehydration. Between 1957 and 1970,it was utilized for used tire sorting and storage. 3.3 Current Groundwater Use _ There are currently no wells on We subject site,, A new wel is proposed to be constructed as part of the warehouse project. The new well should be located up-gradient (southwest) of the proposed septic system and leach field. The Olin Alkali plant has two production wells used an average of 1,151,825 gallons of water per month during 2013. Based on the letter from SJCEHD, due to the groundwater contamination from the Olin Alkali Plant, all future wells in the vicinity will require a minimum 200 foot annular grout seal as directed by the Central Valley Regional Water Quality Control Board. 4.0 SOURCES AND CALCULATED IMPACT OF NITRATE TO GROUNDWATER Per SJEHD requirements, the following summarizes our nitrate loading calculations for the proposed leach field. The state drinking water standard for nitrate is 45 milligrams per liter(NO3) and 10 mg/J as Nitrogen (N) in groundwater. Presented below is our evaluation of nitrate loading