SITE INFORMATION AND CORRESPONDENCE_CASE 2

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WASTE DISCHARGE REQUIREMEtw-.6 ORDER NO. R5-2007-_ VA./ 7 CITY OF TRACY AND LEPRINO FOODS COMPANY LAND DISCHARGE UNITS OF THE TRACY WASTEWATER TREATMENT PLANT SAN JOAQUIN COUNTY compliance with narrative water quality objectives may be evaluated considering numerical criteria and guidelines developed and/or published by other agencies and organizations. Groundwater Degradation 21. The shallow groundwater in the vicinity of the Facility is high in salinity and exceeds water quality objectives. In situations where the background water quality exceeds water quality objectives, the Basin Plan at page IV-15.00 states that, "Controllable water quality factors are not allowed to cause further degradation of water quality in instances where other factors have already resulted in water quality objectives being exceeded." 22. The record indicates that Regional Water Board staff have been concerned about possible groundwater degradation caused by the Discharger's use of its unlined industrial ponds dating back to 1989. A discussion of several groundwater studies performed by the Discharger since that time is provided in the Information Sheet. Monitoring data provided by the Discharger indicates that the unlined industrial ponds may be adversely affecting groundwater. See Figure F-1 of Attachment F, which is attached hereto and made part of this Order by reference. The Discharger has argued that the groundwater quality in the vicinity of the Facility is variable and naturally high in salinity, therefore, it is difficult to determine whether degradation has occurred, and if so, whether the ponds are the cause of the degradation. 23. The Discharger has utilized the ponds for many years, so any assimilative capacity in the shallow groundwater basin has likely been exhausted. In addition, as discussed in Finding 12, the depth to groundwater only ranges from 14 to 18 feet bgs near the industrial ponds. Therefore, the attenuation of wastes in the soil column is likely minimal. 24. In a 1995 report regarding groundwater conditions, the City concludes that the unlined industrial ponds percolate wastewater to the shallow groundwater. However, the City states that there is not adequate evidence that the ponds have degraded groundwater due to the variability of groundwater quality in the vicinity of the Facility. 25. Based on 28 samples collected by the Discharger from 30 November 1994 to 25 May 2004 at upgradient well MW-5, the groundwater upgradient of the industrial holding ponds contained an average TDS concentration of 1,740 mg/L. Groundwater underlying the ponds (as measured at MW-2, MW-3, and MW-4) contained an average TDS of 2273 mg/I. This data indicates that the unlined industrial holding ponds may be adversely affecting groundwater quality. 26. In 1997, Heinz Food, Inc. ceased discharging up to 2.0 mgd of tomato processing wastewater to the industrial ponds during the summer months. Since that time, Leprino has been the primary discharger to the City's industrial holding ponds. Because less wastewater is discharged to the ponds, there is a longer detention time resulting in a greater evapo-concentration of salts. Pond monitoring data collected from October 2000 to March 2005 show an increase in EC from May to October each year and the EC measured in the downgradient wells follows the trend of the pond data (see Attachment F, Figure F-2).