SITE INFORMATION AND CORRESPONDENCE

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ALL PURE WORKPLAN REVIEW -2- 30 October 1989 Based on the data collected and the above results, the report concluded that two separate contamination plumes exist at the site: 1) a fuel hydrocarbon plume is located along the eastern fence line of APC's property adjacent to an abandoned pipeline, a railroad, and an active pipeline; 2) a separate non-fuel hydrocarbon contamination plume is located in the immediate vicinity of Pond #2 and contains chloroform and other volatile organics. Comments on the Assessment are listed below: 1 . We concur with All Pure that the fuel hydrocarbon plume is apparently from an offsite source and should be treated separately from the volatile organic plume. 2. The data presented in the Assessment indicates that the ground water is polluted with chloroform and other volatile organics at the northeast side of Pond #2. The extent of contamination needs to be further defined. A phased approach to define the extent of contamination is acceptable. 3. The report stated that the shallow subsurface water at the All Pure site appears to be an aquiclude. The subsurface geology consists of clay with little or no fine grained sediment. Therefore, the report concluded that the ground water sampled from boreholes was from a local perched aquifer. Although a perched aquifer may exist at the site, not enough data was presented to support this conclusion or the above statements. Also, clays are fine grain sediments; therefore, the statement about the subsurface geology is contradictory. Finally, several investigations in the Tracy area have found clay layers; however, the existence of an aquiclude in the shallow zone is highly unlikely. Usually there is interconnection of the water bearing zones in the clay layers. WORKPLAN The purpose of the Workplan is to satisfy Subchapter 15 requirements by determining water quality beneath the wastewater ponds. The main objectives of this Workplan plan should be 1) to determine the water bearing zones; 2) to determine the flow of ground water in these zones; 3) to determine the water quality in these zones. The Workplan proposes to meet these objectives by installing three four-inch monitoring wells with continuous screens from five to fifteen feet adjacent to the wastewater ponds. Soil samples will be collected at five foot intervals during drilling for analysis. The monitoring wells will be installed under the supervision of a California Registered Geologist. Samples will be analyzed at a certified laboratory and the monitoring wells will be measured and sampled on a quarterly basis. Below are comments regarding issues concerning the Workplan: 1 . The main objective of well placement is to the determine direction of the ground water flow in the shallow water bearing zone. It appears that the monitoring wells, especially the well close to borehole TB8, are too close to the ponds and will likely be influenced by the mound under the pond. In general , well location with respect to the ponds is adequate; however, the wells should be placed at a sufficient distance from the ponds so that water