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Lewiston-Auburn Biosolids Composting Facility

Wright-Pierce was the design firm on the selected design-build team that
included Callahan Bros., Inc., as general contractor and Longwood Manufacturing Corp. (LMC) as the composting system supplier.

A primary factor in the selection of this design-build team was its proposal to provide a high quality system at moderate cost, and to tailor the project to the Authority’s needs.

This state-of-the-art horizontal agitated bin composting facility uses a rear traversing compost turner and 10-foot-wide compost bins. Effective odor control is provided in a large biofilter with in-duct humidification. The facility has the capacity to treat 34 wet tons of biosolids per day. This capacity, in combination with the Authority’s well-established program for direct land application, provides a flexible program for reuse of biosolids.

After meeting federal requirements the compost is stacked in the curing area for 21 or more days. There the compost piles are aerated to provide further stabilization. The mixing and composting areas are fully enclosed and connected to a central odor control system. The heating and ventilating systems also aid in moisture removal from the building, an important factor in minimizing corrosion.The biofilter has demonstrated the capability to cleanse the exhaust air to levels well below applicable standards.

Throughout the facility, the materials of construction were selected for their high degree of corrosion resistance. The LAWPCA Composting Facility represents a significant addition to the infrastructure in Lewiston and Auburn. In addition to supplementing the LAWPCA land-spreading program, the facility allows recycling of material that would otherwise be landfilled.

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Project Highlights
  • The Lewiston-Auburn Water Pollution Control Authority (LAWPCA) provides wastewater treatment services to 65,000 people and treats septage from 18 area communities. 
  • In 1991, the Authority completed an evaluation of its long-term biosolids management needs and selected an enclosed, agitated bin composting facility to be constructed on an 118-acre farm in Auburn.
  • The Lewiston-Auburn Biosolids Composting Facility is the first to feature LMC’s unique rear (finish end) bin-to-bin transfer system.
  • The finished compost is a highly stabilized product, suitable for use as a soil conditioner. It is currently being sold to the public and to area landscaping contractors.
  • Odor control is accomplished in an open bed-type biofilter where compost-based media is used to absorb odorous gases, and where bacteria break down these compounds.
  • By creating a valuable soil amendment, the facility will reduce the need for mining of native loam, helping preserve the area’s agricultural base.