Title: Addressing TSS Generation in the World's Longest Municipal Brine Line

摘要

The Santa Ana Watershed Project Authority (SAWPA) owns and operates a 72 mile brine linernserving groundwater desalination facilities and other industrial and domestic users in SanrnBernardino and Riverside Counties in California. Problems have been experienced recentlyrnwith the generation of large concentrations of suspended solids within the brine line,rnresulting in added maintenance to remove settled solids as well as significant billing issuesrnfor the authority. Dischargers to the brine line are charged based on a combination of flow,rnsuspended solids, and biochemical oxygen demand (BOD) at their point of discharge.rnSAWPA is in turn charged for these same parameters by a downstream sanitation district atrnthe transition from the SAWPA pipeline to the sanitation district's. Suspended solidsrnmeasured at the downstream monitoring point have been roughly double what they arerngoing into the pipeline, creating concerns about an equitable manner to allocate costs forrnroughly 4,000 tons per year of solids that cannot be measured at the discharge points.rnIt has been considered that these solids may come from some combination of chemical andrnbiological interactions between the brine flows and domestic wastewater, which currentlyrnmakes up 40 percent of the brine line water. SAWPA authorized an extensive water qualityrnstudy to determine and characterize the source or sources of this solids generation. It wasrndetermined during the first stage of testing that both chemical precipitation from hardnessrnand silica and biomass formation were significant contributors to the suspended solidsrngeneration. Based on these preliminary results, SAWPA instituted a hardness fee to allrndischargers in order to help cover the revenue imbalance created by the suspended solids.rnThe final stages of the water quality study are expected to be complete in October 2008 andrnwill include chemical precipitation and biogrowth models to project and verify contributionsrnof suspended solids from each of these sources. Results of this study will be used as the basisrnfor permanent changes to the rate structure for brine line dischargers and will be used torndevelop a recommended maintenance program to address the solids generation.