ARCHIVED REPORTS XR0005786 - Laserfiche WebLink

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' SOS CLASSIFICATION: According to the publication issued by the University of Calif. , Berkley, in 1952, The surface soils consist of Stockton Adobe ' Clay and Honcut Clay over Capay & Stockton. These soils are derived from alluvial fans & floodplain deposits; they have good surface and intermediate subsoil drainage, with a Storie index of ' SB. PLATIR III is a portion of the soil, profile map from that publication- P O GROUNDW Data obtained from the three (3) monitoring wells recently placed on the property show that the water table is about 21 feet below ' ground level at this location; it has been reported to be as high as 15' bgl during the past 10 years. PLATT IV is a portion of the San Joaquin County Flood Control District map showing water ' table depths in the Spring of 1986. B IT s O OR NQRK, 1989 - Two (2) 1,000 gallon UST's, which had contained gasoline, mere .moved from the property. Contamination was oeaasured in soil samples taken from the site. ' April„ 1993 - three (2) 2" diameter groundwater monitoring wells were placed on the property, (see PLATE V. ) Minor soil contam- ination was encountered in MW-I & MW-3; none was found in NW-2. BTTX & TPH-G were measured in the water samples from MW-1 & W-3; the highest levels were in Tial--1 . Only benzene was detected in MW-2. The hydraulic gradient was indicated to be to the south- east. Judy. 1993 - Quarterly monitoring revealed BTTX & TPH-G in all three wells; highest levels still measured in MW-1. The gradient ' as measured was due east. A)ovetaber. 1992 - Quarterly monitoring revealed that MW-1 still ' measured the highest levels of BTTX & TPH--G; lesser amounts recorded in wells 02 &a 03. The hydraulic gradient had shifted to a northeast direction. The high levels of contamination consis- tently recorded in MW-1, which is in an up-gradient position from the site of the removed tanks, indicated that there may be an unknown source to the wast or north of the property. ' December, 1993 - An extensive title search of the area to the north and west of the property was trade in an attempt to locate possible offsite sources of contamination. Done were identified. 3