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Marley Cooling Tower Company -2- 28 November 1990 14 November 1990 Meeting Minutes pattern, then the concern with incomplete plume capture during worst case conditions (July 1990) would diminish. The model lacks data in the area, of the Solari property to the south of the site. Because MCTC has been unsuccessful in obtaining access to this property, the southern edge of the chromium plume cannot be modeled. MCTC indicated that two to six more monitor wells may be needed to define the plume edge. Sampling of all of the domestic wells in the area of the Solari property has not found chromium contamination above the Primary Drinking Water Standard (50 micrograms per liter) . The Regional Board indicated that we would approach the Solari and Columbini property owners to try to persuade them to provide access for the installation of monitor wells. It was agreed that data from the 1990 to 1991 wet season should be collected and analyzed prior to installing monitor wells along Walker Lane because ground water will only flow in that direction under continued drought conditions. MCTC is confident that the treatment system design is flexible and although it was designed for the southward movement of the plume, it can be modified for any potential eastward movement of the plume. Therefore, MCTC is eager to build the system and to begin final ground water treatment system. SCHEDULING The current expansion of the treatment system is the first of two planned expansions. This first expansion will increase treatment up to 0.59 million gallons per day (mgd) (410 gpm) . The second expansion will increase treatment up to 0.72 mgd (500 gpm) and is targeted for September 1991 . This expansion will be included in the five year renewal of the NPDES permit which is scheduled for June 1992. MCTC has been evaluating the use of injection wells as an alternative disposal method. The preliminary studies have indicated that injection may interfere with the plume capture in the area of the North Yard. The report on the evaluation of alternative disposal methods is due in December 1991, 18 months after the submittal of the Remedial Action Plan (RAP) . The Regional Board requested that the alternative disposal report be submitted prior the implementation of the second expansion so that this information can be incorporated in the NPDES permit revisions for the second treatment system expansion. MCTC agreed to expedite the technical and economic evaluation of reinjection with a target of March 1991 . Once this evaluation is completed and reviewed, a decision will be made as to whether a pilot study is justified. NPDES PERMIT MODIFICATION The current modification of the NPDES permit will need compliance with the California Environmental Quality Act (CEQA) process. The exemption process was used in the last revision of the NPDES permit. The toxicity studies performed by MCTC have indicated that the effluent does not appear to be toxic using fathead minnows. However, the initial chronic toxicity studies using Ceriodaphnia have indicated that the effluent may cause instream toxicity. Additional chronic toxicity studies using Ceriodaphnia are needed to confirm these initial findings.