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Mr. Dennis Abrahamson -2- 31 October 1991 <br /> Lawrence concludes that effluent disposal impacts on the deep aquifer are not <br /> discernible. However, this does not mean that Simpson is not discharging a <br /> "designated waste. " Lack of a current impact on ground water does not <br /> indicate that a discharge is not a "designated waste. " A "designated waste" <br /> is one which consists of or contains pollutants, which under ambient <br /> environmental conditions at the waste management unit, could be released at <br /> concentrations in excess of applicable water quality objectives, or which <br /> could cause degradation of waters of the state. The threat to the other <br /> ground waters of the site must be evaluated. <br /> Lawrence indicates that there is a regional increase in TDS in the lower <br /> aquifer. We question the result of the many slopes drawn to represent yearly <br /> increases in TDS. Were regression analyses done? For example, Lawrence <br /> concludes that TDS is increasing at a rate of 18.0 mg/1 at well TIS/R6E-26101 . <br /> even though the 1974 TDS was 764 and the 1989 TDS was 550. Similar erroneous <br /> analyses are shown on Figures 8, 10, 12, 13, 19. <br /> Questions about the validity of Lawrence's regional ground water study are <br /> moot since Chapter 15 requires the comparison of downgradient ground water <br /> with upgradient groundwater to determine the impact of a waste discharge. <br /> Therefore, we will not accept the results of the regional ground water study, <br /> even if they are corrected. <br /> Simpson must demonstrate that its waste water discharge, below some particular <br /> TDS level , will not be released into the semi-perched ground water at a level <br /> which would cause ground water concentrations to exceed applicable water <br /> quality objectives or which could cause degradation of waters of the State. <br /> Since the Simpson discharge is already above applicable water quality objectives, <br /> it is necessary for Simpson to demonstrate that the discharge will not cause <br /> degradation of ground water at the Ripon Mill site. This demonstration must <br /> involve diffusion of the Mill effluent into site ground waters as well as the <br /> rate of flow of ground water across the site and the quality of ground waters <br /> entering the site. A Technical Report addressing the above concerns must be <br /> submitted to our office by 1 February 1991. <br /> We have also reviewed the 7 August 1991 Ground water Monitoring Plan (Plan) . <br /> Based on this report we have drafted a proposed Monitoring and Reporting Program. <br /> A copy is attached. Please review the draft copy and send your comments, if any, <br /> to us by 1 December 1991. <br /> If you have any questions, please contact me at (916) 361-5737. <br /> 644�4�� <br /> ROBERT EVANS <br /> Project Engineer <br /> RAE:mdm <br /> Enclosure <br /> cc: Mr. Ron Valinoti , San Joaquin County Public Health Services, Stockton <br />