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i �p A water sample was obtained from a hose bibb at the front of the Tivald,s house after the well was allowed to cycle three time' to ensure a sample of aquifer formation water. The sample was placed in a cooled ice chest andjtransported under the attached Chain of Custody to A &L Labs in Modesto, California. I Water analysis reveals a low nitrate concentration of 10 ppm. The Maximum Contaminant Level (MCL) for NO3 in drinking water is 45 ppm. This 10 ppm concentration may be considered a background concentration that All accumulated over eons and can be attributed to the deep groundwater, high clay content intervening strata, very low septic system density and no intense (fertilized) agriculture surrounding the property, until recently. i ' i CONCLUSIONS The pert test results for Parcels!1, 2, 3 and 4 show acceptable percolation for the management of septic system effluent flows at the deeper depths. However, testing at the shallow depths which are representative of leachlines indi8ate virtually no percolation during the actual percolation testing. Approximately 66% of the pre-s�lak water did percolate over the 24-hr period. Consequently, deeper septic system structures,`sumps for Parcels 1 and 2 and seepage pits for Parcels 3 and 4 may manage most of the effluent volume flows from future residential structures. The perc tests for Parcel 1 were I conducted at depths typically representative of leachlines and P Yp Y sumps. Since favorable, passing!rates were obtained at the 8-foot depth, sumps may be installed on this Parcel. As noted for the shallow test, there will be some effluent percolation at this depth,but if the soil becomes saturated,percolation will cease and the sumps will manage effluent flows. Pere test results for Parcel 2 also indicate failing rates at the shallow depths, although there will be some effluent percolation. Favorable rates at the 12.8-foot depth were obtained where a sandy silt/silty sand was encountered. Parcel 3 perc tests again reveal no"existent percolation at the shallow depths and favorable percolation at the 10.5 foot depth,where a clayey, gravel stratum was encountered. Since there is no proposal to build a second unit dwelling on this Parol, seepage pits would only be installed if there was a failure with the Tivald's existing system. Parcel 4 shallow perc test indicates a nonexistent perc rate at the shallow depths. However, the perc test had started out with acceptable percolation. This may be due to the ability of the silty, clay soils to initially accept a large volume of water, but then swell to become impermeable. Found at 14.8 feet is a well-graded gravel stratum. Therefore, seepage pits are warranted for this Parcel. I i A new law that is to be implemented may outlaw seepage pits (Assembly Bill 885). Before this law A now law that is to be implemj is implemented, EHD may requir"e the installation of seepage pits on Parcels 1, 2 and 4 of this project for a number of reasons::, . I Page -4- J I Chesney Consulting li