The surge facility tested in this EPA Demonstration Project provided peak flow equalization and some degree of treatment to all storm flows and rate control of all wet and dry weather wastewater flows. The Rohnert facility was designed to test a method whereby solids could be prevented from accumulating on the bottom of an inexpensive earthen, lined basin without the use of conventional mechanical sludge collection equipment. The principal features of the surge facility were a 2,841 cubic meter (0.75 million gallon) Sedimentation-Equalization Basin, variable underflow pumps, a surface aerator and Pool Sweeps. The Pool Sweeps were used to continuously 'sweep' the bottom and sides of the earthen, lined basin to move and temporarily resuspend the settled sewage solids and, thereby, maintain the flow of solids in the absence of mechanical collection mechanism, steep bottom slopes, or a completely mixed basin. Under the storm flow conditions, the surge facility removed approximately 45% of the influent Suspended Solids and 90% of influent Settleable Solids prior to overflow to a storage pond.

Prepared for City of Rohnert Park, California and the National Environmental Research Center, Office of Research and Development, U.S. Environmental Protection Agency under demonstration project S800769, program element 1BB034.