SITE INFORMATION AND CORRESPONDENCE

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� 'QW GEOSYNTEC CONSULTANTS Mr. Robert S. Fagerness 14 August 2000 Page 3 during the first two months of the 2000 irrigation season. Within 1 day after monitoring began, the canal EC rose above the 700 µmhos/cm threshold. Except for the first day of monitoring, the EC in the irrigation canal fell below the 700 µmhos/cm limit for a period of only 17 nonconsecutive days from late April to mid May 2000. According to Mr. John Burke with the Bureau of Reclamation in Sacramento, California, the Vernalis Adaptive Management Program (VAMP) was most likely the cause of approximately 11 days of lower EC readings. The VAMP is an agreement between water rights holders and regulators to increase flow in the San Joaquin River through the release of fresh reservoir water from mid-Aril to mid-May. The remainder of the lower EC readings immediately followed a period of late-season rain. Future affects on EC in Lateral 4 North from the VAMP and late-season rain will be short-term and unpredictable in nature. We agree with your recommendation that the groundwater extraction and remediation system could be more effective if it could operate for greater periods of time than it does currently. More frequent and continuous groundwater extraction would increase the capture zone of the extraction pump and further limit the downgradient migration of site-related compounds. However, we are limited in our ability to increase the operation of the groundwater extraction and treatment system due to the EC discharge limitations of the Permit and other limitations such as no sewer system in the area, off-site access restrictions, and limitations for agricultural application,. GeoSyntec is open to discussion of amending the Permit to allow the groundwater treatment system to operate more frequently. Possible amendments include allowing discharge to the irrigation canal when EC in the effluent is less than EC in the irrigation canal and when water in the irrigation canal is utilized to the point that it does not reach the San Joaquin River. GeoSyntec would appreciate the opportunity to discuss these options with you either over the telephone, or in a meeting. If you have any questions or comments, J:\WFS\SHELL\VER\NPDESVuIy 2000 Inspection Rpt..doc r� `, %CICIED AND AECICLABLE .^;