SITE INFORMATION AND CORRESPONDENCE

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Mr. Robert Garcia • 11/19/01 Leprino Foods, Inc. 2 Comments: 1. There was a 0.4-foot rise in the water level at northern boundary monitoring well RW-2 between June and September 2001, which might be the result of a lack of hydraulic containment of the groundwater contaminant plume, and is not consistent with the seasonal decline in site water levels. Adjacent monitoring well RW-I, which is closer to extraction well RW-4A than RW-2, shows a decrease in the water level of 0.2 feet over the same period, which is consistent with hydraulic containment, but could also be the result of seasonal water level fluctuations. Please provide an explanation for the contradiction in water levels for these adjacent monitoring wells. 2. In our letter dated 25 May 2000, we requested that a capture zone analysis evaluate the groundwater extraction system, and suggested that extraction wells RW-1 and RW-2 could be reduced to monitoring wells. At our meeting on 13 October 2000, the presentation of the capture zone analysis showed groundwater plume containment with extraction wells RW-4A and RW-5A. It now appears that the plume might migrate offsite. Additional groundwater monitoring of wells RW-IA and RW-2A is necessary to determine whether the current extraction scenario, using RW-4A and RW-5A alone, is containing the plume. Please closely evaluate the monitoring data to determine whether the plume is captured. If the analytical results of monitoring two additional quarters show that the contamination levels are rebounding, evaluate whether restarting RW-1 and RW-2 as extraction wells will enhance the capture of the groundwater contaminant plume. If you have any questions, you may contact me at (916) 255-3050. �Jr- aures L. Barton, G. Federa]/Private Sites Cleanup Unit LD cc: Mr. Mich l Infuma, San Joaquin County Environmental Health Services, Stockton Mr. Brendan Shine, HSI GeoTrans, Westminster, CO