Item A-MWMC Facilities Plan - Laserfiche WebLink

Home Browse Search

6, DEVELOPMENT AND EVALUATION OF ALTERNATIVES · Proceed with Alternative 3 - develop the BF for effluent reuse through the construction of a dedicated effluent irrigation pipeline and installation of irrigation pumps. · If all reuse projects identified in Alternatives 1 through 4 are successful (publicly and operationally), go forward with measures to implement Alternative 5 - full scale Level IV reuse of 2.5- to 5.0-mgd of additional Level IV reuse. 6.5 Biosolids Management Solids management is accomplished through processes located at the WPCF, BMF, and Biocycle Farm. Processes located at the WPCF include two gravity belt thickeners (GBTs) and three mesophilic anaerobic digesters. Processes located at the BMF include four FSLs, three belt filter presses, and thirteen air-drying beds. The Biocycle Farm is a 595-acre dedicated biosolids land application site planted in poplars and grass. Approximately 7,500 acres of local cooperative farms are also available for land-applying dewatered biosolids. Primary clarifiers thicken settleable solids and skim fats, oils and greases. These solids are pumped to anaerobic digesters. Waste activated sludge produced in the secondary treatment process at the WPCF is thickened through the GBTs and is then pumped to the anaerobic digesters. Anaerobically digested sludge overflows to sludge holding tanks. Sludge holding tank solids are then pumped from the sludge holding tanks at the WPCF through a 5.5-mile pipeline (biosolids force main) to the FSLs at the BMF. Biosolids are discharged into the FSLs where it remains for approximately 3 years. Each year from March through September the biosolids in the FSLs are removed. A dredge is used to pump biosolids (stabilized sludge), out of the FSLs, where it is then dewatered through three belt filter presses. Dewatered biosolids are then stored in static piles in the air-drying beds where they are periodically turned and windrowed. A small portion of the annual biosolids production (less than 5 percent) is composted through aerated static piles. Beginning in July the dewatered biosolids are trucked to local cooperative farms where they are land-applied as a Class B biosolids product. Beginning in the summer of 2004 the first of three phases of development at the Biocycle Farm will become operational and will be able to receive liquid biosolids from the FSLs, as well as dewatered biosolids from the belt filter presses. MWMC also owns the 290-acre Seasonal Industrial Waste Facility (SIWF), which is located approximately 1 mile northeast of the BMF. The site includes a 14-acre lagoon and approximately 215 acres of farmable land. The site was originally constructed to treat industrial liquid waste. The farmable land is currently being leased to a farmer. Currently, the SIWF provides MWMC with a buffer against future regulatory, environmental, and process changes. 6.5.1 Biosolids Stabilization Processes MWMC achieves biosolids stabilization through anaerobic digestion FSLs, and dewatering (primarily mechanical). Anaerobic digestion and the FSLs are interrelated in functioning to stabilize solids through the reduction of pathogens and volatile suspended solids (VSS). Further pathogen destruction occurs following the dewatering process when the dewatered cake is windrowed to a dry solids content of 40 to 50 percent. The capacities of these processes are sufficient to treat the current flows and loads seen at the WPCF. However, MWMC_6.O_REV11.DOC 6-31