SITE INFORMATION AND CORRESPONDENCE

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Memo to Gregory Vaughn -3- 6 March 1989 Page 26 The cluster site of a shallow, intermediate and deep monitoring wells proposed in the northeast corner of the site must be moved as it is within 100 feet of a leachfield and may violate San Joaquin County well siting regulations. This cluster site should be moved to the east or southeast of the main factory building which would be greater than 100 feet from the leachfields and will provide ground water flow control to the east. The shallow and deep monitoring wells (KI-2 and KD-2) cluster site proposed off-site to the southeast should be moved on-site to the northwest and should be included in a cluster with TP-2A. Moving this cluster on-site would eliminate the need for shallow well monitoring well KS-2. This cluster site would provide flow control to the southeast and is an on-site location to detect any potential contamination from adjacent off-site sources. The shallow monitoring well location (KS-4) proposed south of the main factory building should be eliminated, especially if a cluster site is placed to the east or southeast of the main factory building. A shallow monitoring well is needed in the immediate area of Pond l as this is currently inadequately monitored. If elevated concentrations of heavy metals are detected in the ground water from this well , additional monitoring wells will be required to determine the horizontal and vertical extent of ground water contamination. The shallow monitoring well location (KS-3) proposed in the northwesterly portion of the site is a good location for ground water flow control , but may be moved to the immediate area of Pond 2N if the 40 CFR prescriptive standard for three downgradient monitoring wells is required. Page 27 The intermediate monitoring well location (KI-4) proposed to the east of Pond 2N should be moved to the west and should be included in a cluster site with SMW-5 if possible, as this is the area of the highest concentrations of VOCs detected in ground water. An intermediate well should be added to the cluster site of SMW-3 and UMW-1 and should be located on the northwest side of DMW-1, to enable triangulation for this water-bearing zone. Page 28 A deep monitoring well should be included as part of a cluster site in the area southeast of Pond 2N as this is the area of the highest VOCs detected in the ground water. Based on electric logs from DMW-1 and CWS-77, the thickness of this coarse-grained zone is approximately 40 feet. The Hargis pian states that screen lengths will depend on the thickness of this coarse-grained interval . The screened interval for deep monitoring well should not be across potential separate water- bearing zones, but should be representative of a single water-bearing zone. Page 29 The duration of the aquifer testinq, the number of observation wells per test or the proposed methods of analyses was not included in this section.