Chittenden Solid Waste District, Vermont
The Chittenden Solid Waste District (CSWD) in Williston, Vermont, selected SCS Engineers to prepare a business analysis and provide design services for CSWD’s organics diversion facility (ODF), home of Green Mountain Compost. SCS’s design services include expanding and improving the current aerated static pile (ASP) composting system and facility using a hybrid approach to lower costs.
Business and Environmental Challenges
Since its grand opening in 2011, the Organics Diversion Facility has seen more than double the tons of incoming food scrap. The increase in materials, coupled with the layout and design of the ODF, led to inefficiencies. The facility operations required excessive material handling, extensive residency times for the compost, and low yields of the finished compost. In addition, CSWD was using a two-phase ASP process, followed by screening and curing. Early-stage screening resulted in a low fine yield.
When Vermont’s Universal Recycling law reached its highest level of diversion in July 2020, CSWD needed to be better prepared to manage 10,000 tons of food scraps and possibly more. As a result, CSWD’s Board of Commissioners directed staff to focus on efficient diversion and process quality.
For the business feasibility analysis, a cost-benefit analysis was added to project the sufficiency of existing revenues to fund personnel costs, operating expenses, capital program, and debt service while maintaining adequate debt service coverage and working capital reserve requirements over a multi-year project period.
Recommendations and Benefits
SCS recommended combining ASP and turned windrows to achieve process and cost efficiencies. Purchase and use of a windrow turner and dump truck, in conjunction with CSWD’s existing Phase 1 ASP system, is a versatile system that efficiently produces high-quality material.
SCS also recommended grading and surface improvements for both the windrow pad and the sales area to allow year-round use, processing, and materials sales.
A business plan and recommended adaptations enable 8,200 more tons of food waste, for a total capacity of 13,200 tons, and identified the level of District support (subsidy) needed.