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STATE OF CALIFORNIA-Environmental Protecf.►-gency ..ice./ PETE WILSON Govemor CALIFORNiA REGIONAL WATER QUALITY CONTROL BOARD CENTRAL VALLEY REGION " 3443 Routier Road,Suite A -- Sacramento,CA 95827-3098 PHONE:(916)255-3000 FAX:(916)255-3015 Dorn+ RFr4-F='VED NOV 0 6 1996 4 November 1996 Mr. Nathan Esformes I--NVIRONMENTAL HEALTH Triple E Produce PERMIT / SERVICES P.O. Box 239 Tracy, CA 95378 GROUND WATER MONITORING PLAN, TRIPLE E PRODUCE TACILITY, TRACY, SAN JOA QUIN COUNTY I have reviewed the 11 September 1996 letter from your consultant Condor Earth Technologies Inc. (Condor) regarding the Ground Water Monitoring Plan for the Triple E facility in Tracy. The letter responds to four issues of concern in my 23 August 1996 letter. My comments below are in reference to the noted sections of the 11 September letter. Sampling Program The proposed methods for analyses of total trihalomethanes and standard minerals are acceptable. The detection limits for trihalomethanes must not exceed those detection limits previously obtained for the Triple E site. Well Purging Purge water from MW-1, MW-2, MW-5, MW-6, and MW-7 is proposed to be discharged to the aeration pond if chloroform concentrations are greater than 4.5 µg/l and purge water from MW-3 and MW-413 is proposed to be discharged to the soil surface unless chlorform is detected in consecutive sampling events. Purge water from any of the monitoring wells may not be discharged to the ground surface if any detectable chloroform was present in the monitoring well during the preceding four quarters of sampling, unless a current sample of the water to be discharged does not have detectable chloroform. Monitoring for Ground Water Limitations The waste constituents referred to in Section C.1.a. of Waste Discharge Requirements (WDRs) Order No. 96-118 are those which Triple E is required to analyze for under the ground water monitoring portion of the monitoring and reporting program. These include total trihalomethanes, specific conductivity, total dissolved solids (TDS), and standard minerals. We are not requiring and did not require Triple E to conduct a full Article 5 statistical analysis of each constituent in ground water. Triple E should propose a procedure to evaluate those constituents which may appear to be increasing above background concentrations. Reporting The need for isoconcentration and ground water contour maps is justified considering the changes expected in ground water levels and ground water quality due to operation of the ground water extraction system. To minimize the cost of these maps, it would be acceptable to simply plot ground water elevations and chloroform concentrations on a base map which shows all extraction and monitoring wells, the aeration pond, and the apricot orchard spray field.