SITE INFORMATION AND CORRESPONDENCE_CASE 2

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STATE OF CALIFORNIA _ GEORGE DEUKMEJIAN,Governor CALIFORNIA REGIONAL WATL-r QUALITY CONTROL BOARD— ^ ,, CENTRAL VALLEY REGION 3443 ROUTER ROAD s,S SACRAMENTO.CA 95827-3098 15 July 1988 ✓✓✓JUL 18 1988 V Mr. John Baker ENVIROMENTAL HEALTH Utilities Director PERMIT/SERVICES City of Tracy P.O. Box 1029 Tracy, CA 95376 REPORT OF RECENT INSPECTION, CITY OF TRACY, SAN JOAQUIN COUNTY Enclosed is a copy of a memorandum covering an inspection of your treatment plant on 28 April 1988. Although the results from the samples taken on 16 May 1988 indicate that the plant is meeting its waste discharge requirements, we are concerned with the consistent biotoxicity of your effluent, in violation with your waste discharge requirements, and with the high Total Dissolved Solids (TDS) concentration in your effluent. We request you submit by 1 August 1988, a Technical Report on the biotoxicity including a description of how you run the biotoxicity tests, the water quality data and flow rates (volume/day) of the tests run during the last 4 months (see EPA' s Acute Toxicity Manual 600/4-85/013 pg. 41 , Table 7 ) and any readily available information on the dilution capacity of Old River. We propose to meet with you on-site to further discuss how the City can proceed with determining the cause of the biotoxicity and eliminating such toxicity. To determine the instream toxicity, if any, resulting from Tracy' s discharge, the dilution capacity in Old River is critical . We are further requesting that you submit a Technical Report by 1 September 1988, confirming the effluent TDS concentration, evaluating the TDS sources, and potential measures for reduction. The report should evaluate TDS levels in the treatment 'plant ' s influent and effluent, the water supply system, and the receiving water. You may have sufficient existing data available already to do this evaluation. Since there maybe substantial seasonal changes in TDS levels, you should review TDS data over at least a one year period. Also, the dilution capacity of the receiving water will be an important factor to consider in establishing TDS limits at your treatment plant discharge point. The dilution information may be ascertained by at least three methods: conducting dye studies, constructing a flowmeter in the Old River near the treatment plant discharge point, or modifying existing Sacramento-San Joaquin Delta Estuary computer flow models (such as the Fisher model ) to predict the dilution and fate of Tracy' s effluent. The latter option would require some instream TDS testing to validate the model . You should check with the Department of Water Resources on data available from it' s Old River Tracy Road Bridge Station. In case you do not have sufficient existing data available on TDS or on the dilution capacity, the Technical Report should include a specific proposal as to how you will obtain the necessary data, includinq a time schedule.