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y *AW STATE OF CALIFORNIA GEORGE DEUKMEJIAN,Governor CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— CENTRAL VALLEY REGION ..�; 3443 ROUTIER ROAD SACRAMENTO,CA 95827-3098 12 July 1989 Ms. Virginia Cahill V t McDonough, Holland, and Allen 555 Capitol Mall , Suite 950 Sacramento, CA 95814 Proposed Monitoring Wells, Teichert Land Company, Stockton, San Joaquin County We have reviewed your 21 June 1989 letter regarding the above subject. We appreciate Teichert's initiative to investigate possible pollution at London Produce and we agree that monitoring wells are appropriate. However, we have a number of questions and/or comments regarding the proposed work plan submitted by LBME Corporation, dated 17 August 1988, and enclosed with your 21 June letter. Our comments are as follows: 1. Dual completion monitoring wells are proposed; the two screened intervals being separated by five feet. It is unclear why dual completion wells are proposed. Besides being difficult to construct and effectively sample, the proposed minimal separation of the screened intervals without regard to lithology will probably not result in monitoring of separate, discreet zones. Monitoring of the deeper portions of the aquifer should be accomplished with separate monitoring wells screened across the appropriate permeable zones. 2. The work plan proposes to use sampling data from existing monitoring wells 4 and 5 as "reference" (background) values. Have water level data been collected which establish that these wells are upgradient (or sufficiently cross-gradient) to be used as background indicators? For that matter, is the placement of proposed monitoring wells 7 and 8 based on water level data to ensure they will be downgradient of the London Produce facility? In Practice, water laurels from all monitoring wellc should be collected during each sampling event and at regular time intervals, then individually plotted on contour maps. The work plan should include this work. 3. The work plan states that monitoring well development and purge water will be discharged to the storm sewer "unless there is some indication of the presence of hydrocarbons or other hazardous material". It is not clear, how, such a determination will be made without sampling. Additionally, if London Produce has polluted the groundwater, this water may not be appropriate for discharge to the storm sewer even though it is not "hazardous" . It would probably be best to contain all waters until properly tested, then dispose of them accordingly.