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20.June 2001- AGE-NC Project No-. 98-0440 Page 4 of'6 - s collected during_UST removals. Results of the ground water and'soiI,sample'analyses aw re shon.oIn ' Tables 2.and 3. On 08,- 09 and 10 July 1998; six soil borings (B.1 through B6) and,four ground water monitoring wells (MW 1 through MW4) were installed at the site to assess the lateral and vertical extent of impacted soil and ground water. Results of the' July 1998 investigation were reported,in the Preliminary Investigation and Evaluation Report (PIER) dated 14 September 1.998 prepared by ' t AGE. Analytical results of soil.samples collected during the July,199$ investigation are summarized .in Table 3. B7 and two ound water monitoring wells (MW5 and MW6) On 19 May 2000, one soil boring (B7) ground were installedatthe site to assess the lateral and vertieal extent of impacted.soil and the lateral extent'. ' of impacted ground water.,Results of the May 2 000.investigation were reported in the Quarterly Report.- Second Quarter 2000 dated 09 August 2000 prepared by AGE. Cross sections depicting lithology and the extent of impacted soil beneath the site are also presented in the Quarterly Report ' Second Quarter 2000. Analytical results" of soil samples collected during the May 2000 investigation are summarized in Table 3. ' The vertical extent ofp'etroleum hydrocarbon impacted soil has been defined. The lateral extent of petroleum hydrocarbon impacted soil has not been fully defined to the east of the former USTs.,The lateral extent"of petroleum hydrocarbon impacted ground water has not been defined toward the ' northeast, but has been in other directions. The vertical extent of petroleum hydrocarbon impacted -ground water has not been defined.' 4.2.- STRATIGRAPHY 1 r Generally a very stiff clay dominates -the,lithology beneath'the site. Two sand intervals were encountered at, feet and 20 feet,bsg. Data from�previous investigations indicate a sand interval extends beneath the center of the site at 10 feet bsg (Sand Zone A) and beneath the eastern portion of the site at 20 feet bsg (Sand Zone B).'The',two'sand zones are illustrated on Figure 5. Cross sections depicting the general lithology beneath the site are presented"in Figures 6, 7.and 8.. 4.3.: HISTORICAL GROUND WATER DEPTH AND GRADIENT Based on data collected from October 1998.-to March 2001 the depth to groundwater has ranged from 8.95 feet to 13.95 feet below the well heads and the'ground;water flow direction has been consistently toward the north and northwest. However, based on information from,the Lines Of • Equal Elevation Of Water',In Wells - Unconfined Aquifer Fall 1990, published by the'California Advanced GeoEnvironmental,Inc.