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e <br /> METHOD OF INVESTIGATION <br /> At this time, it is anticipated that all investigations will be by back-hoe. The extent of refuse and <br /> the extent of landfill closure cap will be assessed by pot-holing. The lack of refuse east of the <br /> access road will be confirmed by trenching. <br /> Pot-holing to determine the extent of closure cap and or refuse will be to maximum depth of six <br /> feet. This depth is based on the experience of Phase 1, in which refuse, if present was found <br /> within 2.5 feet of the surface. The location of the pot-holes will be selected to locate the edge of <br /> refuse or closure cap within 20 feet(Figure 2 and 4). <br /> The exposed sides of the pot-hole will be inspected for the prescriptive clay barrier layer <br /> (Figure 3-Section 1). <br /> If the closure cap layer is evident on the sides of a pot-hole,then the depth,thickness, and <br /> location will be documented, the barrier layer will be repaired with 2 inches of granular <br /> bentonite abutting the clay barrier, and the excavated soil will be replaced and compacted <br /> (Figure 3-Section 1). <br /> If the closure cap is not found, but refuse is found within six feet,then the depth to refuse <br /> and location of the pot-hole will be documented, 2 inches of granular bentonite will be <br /> placed over the refuse, and the excavated soil will be replaced and compacted <br /> (Figure 3-Section 2). <br /> If no closure cap layer or refuse is found to the maximum depth,then it will be concluded <br /> that that location is beyond the closure cap and beyond the extent of refuse. The location <br /> and depth of this pot-hole will be documented, and the excavated soil will be replaced and <br /> compacted. <br /> To confirm that refuse does not extend east of the access road, small trenches will be dug to a <br /> maximum depth of eight feet deep. This depth is based on the experience of Phase 1, in which <br /> refuse, if present was found within 2.5 feet from the surface. Previous excavations east of the <br /> access road extended to between 9 and 12 feet. <br /> If no refuse is found, it will be assumed that there is no refuse at that location. The <br /> location and depth of the trench will be documented, and the excavated soil will be <br /> replaced and compacted. <br /> If refuse is encountered, then the trench will be extended eastward until refuse is no longer <br /> found. The extent and depth to the top of the refuse will be documented, , and the <br /> excavated soil will be replaced and compacted with a 2-inch thick layer of bentonite <br /> included in the backfill. <br /> Removal of refuse will be avoided during all of the investigative excavations. <br /> Phase 2 Investigation Solid Waste/Public Works <br /> Corral Hollow Sanitary Landfill Page 2 of 5 San Joaquin County—January 12,2006 <br />