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f A.� r7Thepercolatiori tests exhibited rapid rates among the three borings. Although the soil in the shallow boring was very wet from the recent, heavy rainfall, a relatively rapid pert rate was obtained. The medium depth pere test also exhibited rapid percolation. This boring was set on top of the encountered sand stratum. The deep pert test was set in this sand stratum, and therefore exhibited a rate that is too fast to be acce table. The following Table summarizes and illustrates the pere test results and the applicable information, including potential septic system structures based on depth of passing rates, proposed acreage, post soak period status and test results for the respective pere test depths: TABLE 2 SUMMARY OF PERCOLATION TEST RESULTS PROPOSED PARCEL PROPOSED PERC POST SOAK FERC TEST AND POTENTIAL ACREAGE TEST PERIOD RESULTS SEPTIC SYSTEM STRUCTURE DEPTHS STATUS Parcel 4 1.03 Acres Shallow-42 Inches No standing water 20.8 minlin Shallow Leachlines Hole very wet before pre-sat and Potentially Medium-9 Feet No Standing Water 6:6 minlin Shallow Sumps Deep-25 Feet No Standing Water 2.1 min/in /B. SURFACE WATER INFORMATION Surface water consists of all other water sources originating on the surface of the project, other than septic system effluent. These sources include rainfall, surface runoff, domestic irrigation and stormwater retention. The San Joaquin County of Public Works- Isohyetal Map indicate 17 inches of rainfall to be the Mean Annual Precipitation in the area of the project. After project development, a percentage of the land surface will be impermeably covered with structures, concrete and asphalt. This will have a minor attenuating effect on the downward migration of nitrate molecules currently"in-transit" and on nitrate yet to be formed. From the soil test results of each tested depth illustrated on Table 2, it is noted that nitrate-nitrogen concentrations exists primarily in the finer-grained soils. The impermeable surfaces will be traded for potential point sources of nitrate: on-site septic systems, lawns, landscaping and the retention basin. Domestic irrigation use from upscale residences on large lots can account for 1,000 to 3,000 gallons of water/day/residence during the spring and summer months (approx. 6 mos. out of the yr). As referenced excel ' d landscape watering can lead to nitr_ oxen lea_c-hin and runoff to o_pe I_a,eq5 an e at_tz l]y�0a the on-site stormwater retention basin. However, during the winter months, rainfall runoff into the proposed stormwater retention basin at the north end of the p12i2SLtMX contribute a dilution effect to err colatln�_effluent. P i Page -6- Chesney Consulting