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' 09 March 1999 • AGE-NC Project No. 98-0432 Page 3 of 7. 2.4. REGIONAL GROUND WATER DEPTH AND FLOW DIRECTION The estimated depth to ground water at the property is approximately 20 feet below surface grade (bsg),based on the map titled Lines of Equal Depth to.Groundwater Spring 1996 published by the ' San Joaquin County Flood Control District and Water Conservation District (FCD&WCD). It is inferred from the map titled Lines of Equal Elevation of Groundwater Spring 1996, also published by the FCD&WCD,that ground water flows toward the northwest in the general area of the.site,but. this may be modified by changing recharge and discharge patterns. Ground water is considered to be of beneficial use and is used for domestic, industrial and commercial purposes. Information obtained from the excavation of soil and soil borings from the site indicates that the depth to groundwater depth at the site is between 1$ and 20 feet bsg. 3.0. PROCEDURES All field work was performed in.accordance with SanJoaquin County Public Health Services'- Environmental Health Division (PHS-EHD) and Central Valley Regional Water Quality Control Board(CVRWQCB)guidelines for the subsurface investigations of underground storage tank(UST) sites. 3.1. PROBE BORING AND SAMPLING B 1 throw h B6 were advanced at the site, under On 03 December 1998, six soil probe borings ( g ) . observation by the PHS-EHD. Probe borings were advanced in the area of the former USTs and in ' the area of the western most dispenser island. Probe boring B 1 was advanced northwest of the former diesel UST, boring B2 was advanced in the . ' former diesel UST location,boring B3 was advanced southwest of the former UST excavation, soil .. boring B5 was advanced northeast of the former UST excavation and boring B6 was advanced southeast of the former diesel UST excavation and east of the former gasoline UST excavation. Soil ' boring B4 was established at the western edge of the westernmost dispenser area and tank set (dispenser 3). Probe boring locations are shown on Figure 2. Borings B 1, B4 and B6 were advanced to a depth of 20 feet bsg. Soil samples,were collected at 5- g . foot intervals,'beginhing at a depth of 10 feet bsg. Borings B2, B3 and B5 were advanced to a_. vertical depth of 30 feet bsg. Soil samples were collected at 5-foot intervals to the total depth of ' B2 and BS beginning at a depth of 20'in boring B2 and beginning at a depth of 10 in boring boring � g g P g .. -B5. Soil samples were collected continuously from 8 to 20 feet bsg and then at 5-fo6t intervals to.. Advanced GeoEnvironmental,Inc.