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Soil Suitability Nitrate Loading Study 1(erracon Recreation Vehicle Service Facility■ Lockeford, CA April 12, 2017■ Terracon Project No. NA177006 The following table presents a log of the shallow and deep soil borings. Soil samples for the deep boring were collected at five foot depth intervals. Table 4. Summary of Soil Lithology. Unified Soil Boring Depth Interval (ft) Soil Type Classification P1 (shallow) 3.5 Silty clay, orange CL-ML brown hh,, �J 5.0 Silty sand, orange SM brown P2 (deep) 10.0 to 15.0 Silty sandy clay, brown CL 15.0 to 20.0 Silty sandy clay, brown CL 20.0 to 25.0 Silty sand, brown SM 1.5.4 Discussion of Soil Lithology A visual inspection of the shallow soils from the boring indicates unfavorable conditions for septic disposal areas due to the silty clay soils. The area is know to have clay strata with depth as well as "hardpan' or cemented soils which have low porosity. For this reason, seepage pits are used C5 cf) with leach lines in this area of the county. Silty sand was encountered between depths of 20 and 25 feet bgs. Seepage pits should be installed to the full depth of 25 feet, maximum allowed by County. 1.6 Percolation Test Information 1 .6.1 Percolation Test Locations (G.� Refer to Section 1.5.1 and Appendix A, Plate 2. 1.6.2 Number of Percolation Tests One shallow and one deep percolation test were conducted. 1.6.3 Boring Preparation and Presaturation A 2.0-inch diameter PVC pipe with perforations towards the bottom was installed on top of the gravel and the annular space was backfilled with "pea gravel'. Approximately two inches of"pea , t gravel'was placed in the bottom of the open borings. Presaturation of the percolation test holes occurred approximately 24 hours prior to the day of testing. Responsive ■ Resourceful ■ Reliable 9