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Estimate potential nitrate impact by conventional septic systems from the residential development of the subject property. Identify past and present sources of nitrate impacting-the underlying groundwater and discuss impact from upgradient septic systems and upgradient agricultural production. Discuss mitigation measures to alleviate nitrate loading from the septic systems proposed for this development. I II. SOIL SUITABILITY STUDY FINDINGS A. SUBJECT PROPERTY AND SURROUNDING STUDY AREA INFORMATION i The current surrounding land use to the north, south, east and west of the project site, as referenced above, has been the same for decades. This is evidenced by the United States Department of Agriculture (USDA) Soil Map of San Soaquin County for this area, produced in the 1970s. The subject property is completely fallow except for a small single family residence, located in the southeast corner of the property that fronts Alpine Road. The address for this residence the address for the entire subject property (767 North Alpine Road). According to Mr. Smith, who has �Z farmed in this area for 35 ears, the property has been fallow for this length of time. lived and y Applications on file with the County Environmental Health Department reveal that there have been 14 permits issued for repairs/additions to existing systems in the one-half mile study radius. One of the permits was for 50 feet of additional drain line and a 33" x 25' seepage pit for the subject 3)' property in November 1968. Seven additional permits were also found for the study area that illustrated seepage pits for new installations. All except two of the peririiffiridicate the installation 3 of seepage pits,_reinforcing the_•premise that.seepage.pits_should be-installedin this locale. These 3 ' ;1.4 permits--also-indicate thaf the Aurroutiditig shallow surface soils are marginally,conducive for the,long-term management of septic effluent;clue to the poor permeability characteristics of these soils. This was also evidenced by the percolation tests conducted for this project. In the eastern and northeastern areas of San Joaquin County, seepage pits are used to manage most of the septic r system effluent. B. - SOIL PHYSICAL.AND CHEMICAL CHARACTERISTICS The project site has level terrain; consequently, there will be no need to incorporate designs LJ considerations for slopes. The United States Department of Agriculture -Natural Resources Conservation Service (USDA-NRCS) shows the on-site soils to consist of Hollenbeck silty clay (#173) and is bordered by Galt clay (#160) to the south.. According to the USDA Handbook, the surface layer is a grayish brown silty clay with a claypan of brown clay below this surface soil. Extending from 27 inches to 60 inches is light yellowish brown weakly/strongly cemented hardpan of cemented silts and clays. The main limitations with these soils are the very slow permeability in the substratum. i 2 - CFcesney Corrsu�ting f . _