Keeping our Biosolids End-Use Options Open - City of Boulder WWTP Solids Dewatering Improvements

The City of Boulder has utilized various biosolids end-use options over the last 20 years as part of its Biosolids Management Program. These options included Class “B” land application both in Boulder County and Adams County, Colorado and transporting liquid biosolids to a privately-owned and operated Class “A” Biosolids composting facility. After evaluating numerous Class “A” and Class “B” biosolids management alternatives over the last two decades, the City have recently completed a solids processing improvement project at its WWTP. The new facilities allow the City to maintain a variety of biosolids end-use options. The current project includes a state-of-the-practice biosolids dewatering, cake pumping and cake storage and truck loading facility at the WWTP. The unique features of this project include: 1) enclosed biosolids dewatering, pumping and storage facilities to minimize housekeeping and odors, 2) operator-friendly building layout with isolation of the operator control room and centrifuge room, and 3) a diamond gate hopper unloading system that can load a semi-truck trailer in less than 60 seconds to significantly reduce the cost for contract hauling. The biosolids are being contract-hauled offsite to land application. If agricultural sites are not available due to poor weather or farming operations, the biosolids are transported to A-1 Organics, a private composting operation where the biosolids are used to produce Class “A” compost that is then marketed as a soil amendment.