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{ <br /> 1 <br /> '. ✓ Estimate potential nitrate impact by conventional septic systems from the residential <br /> development of the subject property. Identify past and present sources of nitrate <br /> impacting the underlying groundwater and discuss impact from upgradient septic systems <br /> and upgradient agricultural production. <br /> ✓ Discuss mitigation measures to alleviate nitrate loading from the septic systems proposed <br /> for this development. <br /> II. SOIL SUITABILITY STUDY FINDINGS <br /> A. SUBJECT PROPERTY AND SURROUNDING STUDY AREA INFORMATION <br /> t <br /> The current surrounding land use to the north, south, east and west of the project site, as referenced <br /> above, has been the same for decades. This is evidenced by the United States Department of <br /> ,.: Agriculture(USDA) Soil Map of San Joaquin County for this area, produced in the 1970s. The <br /> ^ subject property is completely fallow except for a small single family residence, located in the <br /> southeast corner of the property that fronts Alpine Road. The address for this residence is the <br /> address for the entire subject property(767 North Alpine Road). According to Mr. Smith, who has <br /> lived and farmed in this area for 35 years, the property has been fallow for this length of time. <br /> Ft' <br /> Applications on file with the County Environmental Health Department reveal that there have been <br /> 14 permits issued for repairs/additions to existing systems in the one-half mile study radius. One <br /> of the pen-nits was for 50 feet of additional drain line and a 33" x 25' seepage pit for the subject <br /> property in November 1968. Seven additional permits were also found for the study area that <br /> illustrated seepage pits for new installations. All except two of the.permits indicate the installation <br /> ' of seepage pits, reinforcing the premise that seepage pits should be installed in this locale. These <br /> 14 permits also indicate that the surrounding shallow surface soils are marginally conducive for the <br /> long-term management of septic effluent, due to the poor permeability characteristics of these soils. <br /> This was also evidenced b the percolation tests conducted for this project.Y P p � In the eastern and <br /> northeastern areas of San Joaquin County, seepage pits are used to manage most of the septic <br /> system effluent. <br /> B. SOIL PHYSICAL AND CHEMICAL CHARACTERISTICS <br /> The project site has level terrain; consequently, there will be no need to incorporate design <br /> considerations for slopes. The United States Department of Agriculture -Natural Resources <br /> F" <br /> Conservation Service (USDA-MRCS) shows the on-site soils to consist ofHollenbeck silty clay <br /> ri (#173) and is bordered by Galt clay(#160) to the'soutb. <br /> According to the USDA Handbook, the surface layer is a grayish brown silty clay with a claypan of <br /> brown clay below this surface soil. Extending from 27 inches to 60 inches is light yellowish brown <br /> weakly/strongly cemented hardpan of cemented silts and clays. The main limitations with these <br /> soils are the very slow permeability in the substratum. <br /> F <br /> 2 <br /> FChesney Con suft�ing <br />