SITE INFORMATION AND CORRESPONDENCE

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Bert E. Van Voris - 3 - 28 April 2004 Supervising Engineer knowledge of hydrogeology, biochemistry and geochemistry, and must be made by persons registered to practice civil engineering or geology pursuant to California Business and Professions Code §§6735, 7835, and 7835.1. Definitive assessments of the relative contribution of waters with differing qualities to water of known quality cannot be based on constituents subject to biodegradation(phosphorus and nitrate), attenuation (potassium), and potentially produced by decomposition of organics (calcium and magnesium). Rather, reliable assessments for contributive effect must be based on either on controlled dye studies or conservative constituents such as chloride. According to self-monitoring data, the average chloride concentrations in impounded wastewater, seepage, and MW-3 are approximately 250, 550, and 950 mg/L, respectively. Use of these values in a simple mass balance equation' indicates that 57% of the seepage flow is composed of impounded wastewater and the remainder is groundwater similar in quality to MW-3. Groundwater in MW-14, near the head of the reservoir, and MW-15,north of the reservoir's midsection, contains lower concentrations of chloride than groundwater in MW-13. According to self- monitoring data, the average chloride concentrations in MW-14 and MW-15 are 778 and 452 mg/L, respectively. As the concentration of chloride in the seepage is less than groundwater passing through MW-14 and impounded wastewater, the groundwater contribution to the seepage must be from sources other than that passing through MW-14. Use of the average chloride concentration in MW-15 in the simple mass balance equation indicates that 44% of the seepage is composed of impounded wastewater and the remainder from groundwater similar in quality to MW-15. On 21 April 2004, I inspected the reservoir and discharge areas accompanied by Leikam, who reported that he determined the flow from the blanket drain outlet was about five gallons per minute (or 7,200 gallons per day). The steady increase of concentrations in groundwater passing through MW-16 (near the seepage) of decomposition byproducts (i.e., calcium,magnesium, and alkalinity) is sufficient evidence that impounded wastewater is impacting groundwater. Concentrations of these constituents have almost doubled since this well was installed in the fall of 2002. Based on my review of the submitted documents, I conclude that the reservoir liner was not constructed as proposed. This conclusion is consistent with remarks made by Hall in recent meetings that, in effect, Musco determined a constructed liner was unnecessary to prevent groundwater impacts from impounded wastewater due to the low permeability of native soils. Further, from my review of available data, the low permeability of native soils has not been"adequate to prevent the stored wastewater from impacting the groundwater." Task 16, therefore, has not been satisfied. As evidence in the form of chloride concentration data reveals that water emerging from the blanket drain is comprised of wastewater and groundwater, its discharge to the surface water drainage course below the dam constitutes a violation of Discharge Prohibition A.1 of Waste Discharge Requirements Order No. R5-2002-0148. [Cl] * [V] + [Cl] *[V]� = [Cl] v s *[V] v wasiewaler. wastewater MW-3 owtdwater see n e see a e