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A S S 0 G I A T E S I N C s. Soil analytical results are summarized in Table 1. Cross sections showing the subsurface stratigraphy encountered and the vertical extent of impacted soil during the previous investigations is shown on Figures 3, 4, and 5. Copies of boring logs are contained in Attachment 1. SCOPE OF WORK Planninjz and Permits Upon approval of this workplan and boring locations by EHD, ATC will prepare an application to advance the borings in the City of Stockton right-of-way property. After this is complete, ATC will submit proof of access along with the permit applications and associated fees for the soil borings to EHD for approval. ATC will also schedule field personnel and equipment, notify Underground Services Alert to locate underground utilities as required, and perform any other necessary field preparation and job start-up activities. Advancement of Soil Borings To further assess the extent of impacted soil and groundwater at the site, a total of six soil borings will be advanced at the site. The proposed boring locations are shown on Figure 2. A deep soil boring will be advanced using cone penetrometer testing (CPT) methods near former borings SB4 and SB7, the area of highest petroleum hydrocarbon concentrations, to evaluate the deeper subsurface conditions. A cone mounted with sensors at the tip will be advanced into the soil using direct push rods. The sensors will test the response of the soil to the force of the penetrating cone and this will allow the subsurface stratigraphy to be characterized. The boring will be advanced until a significant clay layer is encountered that appears to separate the shallow aquifer from the deeper water bearing zones. ATC estimates that the CPT boring will be advanced to approximately 100 feet bgs. If no significant clay layer is encountered to a depth of 100 feet bgs, the CPT boring will be advanced further if subsurface conditions allow it. Once a significant clay layer has been discovered and the boring is advanced into another sand layer, a Geoprobe boring will be advanced adjacent to the CPT boring and a discrete groundwater sample will be collected from the deeper aquifer. After the sample has been.collected; both borings will be grouted to the surface. PT- b OL5 �j i � �"�• In addition, five soil borings will be advanced using hollow stem augers, and at least two soil samples and one groundwater sample will be collected from each boring. If the boring shows obvious signs of impact by petroleum hydrocarbons, no groundwater sample will be collected and the boring will be completed as a monitoring well. These borings will be advanced to evaluate the lateral extent of petroleum hydrocarbon impacted groundwater. It is anticipated that several of the borings will be advanced at off-site locations. Proposed boring locations are shown on Figure 2. w:192054.0001Vvportslwkp1n_add_inv.duc 3