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Ir NEIL O. AN:RSON & ASSOCIATES,.INC. f � GEOTECHNICAL•ENVIRONMENTAL•GROUNDWATER.•INSPECTIONS•TESTING•LABORATORY SERVICES D en CORPORATE OFFICE SACRAMENTO OFFICE Z �+ 22 Houston Lane 4229 Northgate Boulevard,Suite 3 O, CffiCO (530)891-6304 Lodi,California 95240Sacramento,California 95834 S G q S Q % STOCKTON (209)'472-7091 (209)367-3701 (956)924-9267 RANCHO CORDOVA (916)6314455 FAz:.(209)333-8303 FAX:(916)929-9269 C April 12, 2001 3ob'No.LG00=339 ; ^ Mr.George Rose Western Asset Recovery 900 Post Road , Oakdale, CA 95361 Re: Addendum, Soil Suitability/Nitrate Loading Study 12897 South Cometa Road, Oakdale California. LA-01,-04 . Dear Mr.Rose, Per your request, we have completed our evaluation of new proposed residential parcels located northwest of the intersection of Cometa and Edwards Roads in Valley'Horhe, California. We understand that you propose to create six(6)new parcels involving some property previously evaluated by our office. This work was performed as a new addendum to a Soil Suitability/Nitrate Loading Study dated October 12; 2000 and report addendum letter dated November 27,2000. General A letter from Mr. Rodney Estrada dated February 21,-2001, describes the San.Joaquin County Environmental Health Division's requirements for the lot line adjustments. Requirement A essentially requires'additional percolation testing and an addendum letter to the soil suitability study/nitrate loading study. As a clarification,Mr.Estrada was asked if it was necessary to'conduct a new percolation test on a new proposed lot if a percolation test had beer' performed there during a previous phase of testing. Mr. Estrada said that percolation testing should be performed on all the lots. He said if testing has previously occurred within an area bounded by the new lot line, further testing was not required. He said that the locations of all the old lots,the new lots,the location of old percolation tests,and new percolation tests should be clearly marked on a map. Essentially,each lot requires a percolation test with the exception of new Parcel 5 as described in Requirement A. The soil-suitability study/nitrate loading study was conducted at the site to determine whether the proposed parcels are suitable for the use with a septic system and to estimate the potential impact of Ieaching nitrogen to ground water. The study was performed according to the requirements of Section 9-1105.2(d) of the San Joaquin County Development. The conclusion of the investigation found that a lot size of 2.0 acres or above would not cause nitrate buildup above the maximum drinking water standard established by the Environmental Protection Agency. Each lot size of 2.0,acres and greater was found to be suitable for.use with a residential septic system. Test Borings On April 4,200 1,one test hole and percolation test was set on new Parcel 1,new Parcel 2,and new Parcel 3 (Plate 1). Since new Parcel,4 and new Parcel 6 have proposed lot line adjustments which enclose ' an area previously evaluated by soil boring and percolation test,theseareas did not require further testing.' New Parcel 5 is not a buildable lot and will not require a soil boring or percolation testing as previously discussed: Mr.George Rose a April 12,200 1- :Page 2 ; Generally;the three(3)borings composed of similar materials which consisted of sandy soils with a matrix of silt or clay. Between the depths of 14 feet to 17 feet;a clean sandy stratum was encountered , (Plates 2-5). The thickness of the sand was found to be greater than two(2)feet at each location. This sandy zone was the first sufficiently permeable soil layer encountered during drilling and va's selected for the ' percolation-test. .The soils encountered during the drilling of the three holes were vey typical of soil conditions encountered at other locations of the site. Percolation,Tests .For new Parcels 1,2, and.3; a percolation test was performed to demonstrate the capacity for soil percolation for use with an on-site septic system.The depth of the test was determined by setting the casing adjacent to the first sufficiently permeable material encountered(usually'sandy soil)-found to a maximum depth 6f25-feet. _ter_-.>_-`--`------ " '--'- -"-- -`-- r�.r, '- •.,_ - ,