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REVISED CLEANUP AND ABATEMENT ORDER NO. 5-01-703 -7- CITY 7_CITY OF RIVERBANK WASTEWATER TREATMENT PLANT STANISLAUS COUNTY 26. The geotechnical engineer's report for the northern berm identified three potentially serious problems with the berm. First, portions of the northern berm do not exhibit a reasonable factor of safety under static conditions. Second, portions of the berm do not exhibit a reasonable factor of safety under pseudo-static (seismic) conditions. Finally,the northern berm was determined to be vulnerable to piping if the northern ponds are kept full for long periods. The report recommended that the berm be retrofitted with a rock buttress underlain by a geotextile filter fabric to improve stability and prevent piping. 27. Based on the Water Balance and Capacity Study Report submitted by the Discharger, disposal capacity has been restored by the Discharger's actions, and no additional storage or disposal capacity is needed to accommodate the facility's current flows (4.5 mgd on average during the tomato processing season and 1.8 mgd on average during the rest of the year). However,there is insufficient capacity to accommodate the flow limits set forth in the WDRs or planned growth within the Discharger's service area. 28. Under the original C&A Order, there were four tasks that remained to be completed by 30 October 2003: a. Complete permanent repair of the northern berm of the Winter Aeration Cell and Summer 1 Pond in accordance with the recommendations of the geotechnical engineer, and submit a technical report describing the actions taken to comply with this requirement by 30 August 2002. b. Submit a Report of Waste Discharge to apply for revised Waste Discharge Requirements for the proposed permanent facility expansion as indicated by the water balance by 30 August 2002. c. Certify that the plant expansion has been completed and that all capacity-related problems have been fully resolved by 30 October 2003. 29. The Discharger plans to construct additional percolation ponds and other improvements to accommodate planned growth within the next 18 months. In order to save money, the Discharger would like to consolidate that project with retrofitting the northern pond berm. Therefore,the Discharger requested that the C&A Order be revised to reflect a later deadline for completing the berm repairs. The Discharger recognizes that, in the interim, influent flows must be limited to the demonstrated storage and disposal capacity described in Finding No. 27. 30. The Discharger recognizes the risk of berm failure associated with delaying the berm retrofit and has instituted a program of frequent inspections to identify problems as they arise. There has been no observable seepage since an abandoned underdrain was sealed in 2001, and the Discharger reports no evidence of piping. 31. As a result of the events and activities described in this Order,the Board finds that the Discharger has caused or permitted waste to be discharged in such a manner that it has created, and continues to threaten to create, a condition of pollution or nuisance. 32. The Board's Water Quality Control Plan (Fourth Edition) for the Sacramento River and San Joaquin River Basins (Basin Plan) establishes the beneficial uses of the waters of the state and water quality objectives to protect those uses. The beneficial uses of the Stanislaus River are