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Napa River Dewatering Project
The City of Napa has faced a perennial flooding problem due to Development of the Napa River Watershed. The Army Corps of Engineers is leading a wide range of government agencies to reduce flooding by returning a portion of the flood plain to its natural condition. This massive project will be completed in stages over a period of years.
The first major construction work began in 2002. This phase required the removal of a large volume of sediments along a 1,000 foot section of the riverbank that had been contaminated from almost a century of industrial activity. The main pollutants were oils and fuels from oil terminal and railroad operations. A critical element of the plan was to remove the contaminated sediments from below the water table before the winter rains set in. In order to accomplish this task the engineers determined that a system capable of treating up to 1,000 gallons per minute without shutting down for maintenance would be required. The system would have to not only remove the high levels of oils and fuels, but also high levels of sand, silt, and colloidal clays. The treated water was had to meet the strict discharge limits for the Napa River. For practical purposes, this meant that the discharge had to be less than detection limits for oils and fuels and less than 5 NTU for turbidity. If the contractor could not meet these stringent treatment standards, the project would be shut down.
The General Contractor wanted a complete solution to for the water treatment requirements on this project. They needed someone who could do more than provide the equipment. They needed someone who could design a system that would work; assist with permitting for the system; set up the water treatment system; and monitor the system during operations. The contractor turned to Clear Creek Systems, Inc. (CCS) based upon our strong history of successful water treatment operations under very difficult and demanding circumstances. No single treatment technology was going to be able to solve this problem. CCS used a unique combination of technologies for this project. These technologies included natural polymers in the liquid and solid form, Baker frac tanks, sand filters, CCS’s CS filter cartridges, and granular activated carbon. Due to the critical nature of the operation, the whole system had to be designed to handle all types of contingencies without shutting down for the duration of the project. So not only was the treatment technologies used of vital importance, but so was the system design and operational plan of action.
CCS mobilized the complete 1,000 gpm system from the ground up and was ready for operation within 2 weeks of Notice To Proceed. The system continually met discharge requirements even when the influent turbidity exceeded 2,000 NTU, the discharge turbidity was less than 5 NTU. CCS not only kept the system continuously operational as required, but also handled some unforeseen circumstances beyond the design parameters. The project was completed on time and on budget.
