SITE INFORMATION AND CORRESPONDENCE

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ORDER NO.R5-2002-0148 13 INFORMATION SHEET MUSCO FAMILY OLIVE COMPANY AND THE STUDLEY COMPANY WASTEWATER TREATMENT AND LAND DISPOSAL FACILITY SAN JOAQUIN COUNTY Limited geological mapping of the railroad cuts and other exposed structural features. Staff believe this could yield useful information but it should build upon the work published in professional papers. Kleinfelder recommends preparation of Stiff diagrams to further characterize groundwater quality. Staff agree this action could provide useful information. However, additional wells are needed to better characterize the groundwater quality and hydrogeology of the area. Additional characterization is required to determine if a water table zone exists in the northern area of the site and to allow monitoring of groundwater upgradient and downgradient of the 84-Mgal storage pond. Effluent Limitations Based on the above analysis, staff have proposed an interim background concentrations for TDS (2,047 mg/1), sodium (597 mg/1), chloride (601 mg/1), and nitrate-N(6 mg/1). The Discharger is required to install and monitor additional groundwater monitoring wells onsite, and within two years to propose final background concentrations. To protect groundwater quality, the WDRs contain effluent limitations that match the background water quality. Musco is currently discharging waste at a higher concentration that the TDS and sodium effluent limitations. Therefore, the Board is asked to consider a companion Cleanup and Abatement Order. The C&A provides a time schedule for Musco to reduce the TDS and sodium in its effluent. Musco must meet the effluent limitations within two years. Staff expect that the final background water quality values, and hence the final effluent limitations, will be less than the interim values. Therefore, once the final background water quality study is completed, it is expected that Musco will need to farther reduce the salt in its effluent beyond what is currently required by the C&A. These WDRs require continued groundwater monitoring to fully evaluate the impacts of the Discharger's past and future disposal practices. However, it is not appropriate to follow the Discharger's recommendation to conduct a year of monitoring to determine if there are groundwater impacts, and then design effluent limits based on the groundwater data. In the last year, the Discharger has substantially increased its wastewater flow and strength, and has begun applying wastewater to a larger area. These recent changes may not yet be reflected in the groundwater quality. In addition, the RWD clearly shows that the Discharger intends to apply significantly more salt than will be taken up by the crops; therefore, these WDRs contain limits to prevent impacts to the underlying groundwater. Shallow soil samples were collected in the land application areas in November 1999 and April 2001 as part of the 6 April 2001 Soil Salinity Assessment required by C&A Order No. 5-00-717. The samples were collected to evaluate the wastewater application impact to soil quality. Analysis indicted that 22-percent of samples collected in the Field 55 East and Field 55 West (55 acres total) maybe impacted by the wastewater application and 28-percent of the samples collected in Field 95 (95 acres)may be impacted. The report stated that the high concentration of sodium in the wastewater has the potential to reduce the already low permeability of the soil permeability. Pan lysimeters are required to allow measurement of percolate quality. If percolate quality is worse than background groundwater quality, additional source control or better cropping will be required.