WSPC00006 - Laserfiche WebLink

Home Browse Search

p'" :. ~ l ~l t.' l.~ ". u :It . salinity levels of the component flows would be monitored daily and adjustments made accordingly. Most of the excess Wellton-Mohawk drainage would need to be bypassed along with the salt brine to the Santa Clara Slough. The Wellton-Mohawk return. flow is currently returning about 125,000 acre-feet of irrigation drainage. This quantity of drainage is well above the 108,000 acre-feet per year projected and used for sizing the plant at 73 Mgaljd. If the Desalting Plant were fully operational, about 97,300 acre-feet of this drainage could be treated and some of the remaining 27,700 acre- feet of drainage could be blended with the product water to meet Minute 242. However, most of the untreated drainage water would be bypassed along with the reject salt brine. DESALTING PLANT PROBLEMS AND NEEDS Desalting Plant problems and needs focus on reduqing the operation and maintenance costs and on developing a replacement water source to make up for the reject stream, operational bypass and other unavoidable bypass. Because power costs are a significant part of the operating costs, and because power rates have been escalating in recent years, Reclamation has been analyzing modifications to the Desalting Plant to reduce energy costs. The annual Operations Maintenance and Repair (OM&R) costs, including energy to run the desalting plant, are projected to be in excess of $31 million during years of operation. During years of surplus Colorado River flows the Desalting Plant would not be operational, however, the down time would allow needed maintenance activities on the Reverse osmosis units. During these non-operating years the OM&R costs are expected to be about $8.5 million. I - In operating the Desalting Plant the united States will also incur an obligation to replace the water lost through both the salt brine that is rejected during the desalting process, and any remaining Wellton-Mohawk return flow that cannot be discharged to the Colorado River. While the options to be discussed in this report will address the need to defray the annual O&M costs, the options will not address the Reclamation's need for replacement water. Following initial analysis, it was determined that a unique opportunity could be realized for making multiple use of the Desalting Plant by treating water for the city of Yuma. While the options do require that the city replace the operational bypass, the treatment options do not develop new water for Reclamation. other on-going studies, such as Vegetative Management, are addressing the need for replacement water. 8