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Remediation Report - 152 East 1 lth Street, Tracy, California Page 9 4-cubic-yard bucket and a fleet of end-dump trucks were used for the work As it iprogressed, ramps, leading from the surface into the pit, were formed to permit the excavator, loader and trucks to advance into the excavation so that it could be extended to the requisite depth Removal of Clean Overburden During the first stages of work, the overburden of clean soil above the contaminated zone of the subsurface was carefully excavated Because there was no space available to stockpile this clean material on the property and its geotechnical properties made it unsuitable for use as an engineered backfill to restore the excavated pit, it was trucked off site and recycled in beneficial use as general fill No evidence of the presence of fuel hydrocarbons was found in the overburden soils This includes the area around the former pump island on the north side of the site (See Figure 2 for location) To ensure careful segregation of the clean overburden soils from the contaminated soil at depth, the excavator was used to open exploratory holes in un-excavated areas of the site which exposed the contaminated material before overburden was removed All soil within a minimum of two feet of any soil affected, or suspected to be affected, by components of hydrocarbon fuels was left in place to be excavated as contaminated soil Probina beneath the clean overburden revealed that the depth to the top of the zone of contaminated varied significantly over the area of the site In the southern, southwestern and southeastern areas of the property the top of the zone of contaminated soil, where present was some 8 5 ft to 9 ft beneath the ground surface, but it was found at significantly shallower depth in the northern portion of the site Around the mid point of the East 11th Street frontage, in the vicinity of monitoring well ULT 9, the depth to the first occurrence of contaminated soil was as little as 7 ft to 7 5 ft Note The depth to the groundwater table is approximately 8 5 ft to 9 ft , depending upon the season The topography of the top of the zone of contaminated soil was that of a mound with its pinnacle at some point off-the property to the north, under East i lth Street No mound of contaminated soil, or any other indication that it might have been the source of the contamination affecting the site, was found at the location (see Figure 2) on the 152 East 11 th Street property from which underground tanks were removed in April, 1984 under the permit and oversight of the City of Tracy Cut Off and Capping of Sewers Two sewer laterals serve the site Both are 3-in diameter, ceramic, clay pipes that connect to the municipal sewers under East 11th Street When these pipes were exposed in the remedial excavation at depths between two and four feet beneath the ground surface, they