City of Grand Rapids CASE STUDY

The City of Grand Rapids needed a practical, scalable solution to divert residential food scraps from landfills and incineration while creating a local, accessible organics recycling program. Organic waste makes up approximately 35–40% of the City's municipal solid waste, representing an estimated 13,000 tons of material each year. The Renew Grand Rapids pilot represents a milestone for the Grand Rapids Public Works Department, creating Michigan’s first fully municipal-owned and operated compost program. Through the pilot, the City sought to establish a model for residential food scrap diversion that could be evaluated and expanded over time. A primary driver for the program was meeting Michigan’s (EGLE) target to reach a 45% waste diversion rate—moving the City up from its current 30% by capturing residential food waste.

The residential food scrap drop-off program was designed to increase access to composting and provide convenient options for disposing food scraps, while introducing composting as a practical resource for the broader community. The City plans to make the nutrient-rich compost available to parks, residents, and local community gardens, with a focus on supporting underserved neighborhoods with poor soil quality or limited access to fresh produce. Residents drop off food scraps at 7 smart, app-enabled collection sites across three city wards, equipped with fill-level sensors and animal-proof access control.

The City also wanted to maximize the value of its existing resources by incorporating wood chips produced by its forestry division into the composting process. The program needed to support efficient collection and reliable processing while creating a closed-loop system that would transform locally collected food scraps into a valuable resource for the Grand Rapids community.

Green Mountain Technologies provided the City of Grand Rapids with an Earth Flow IM-40 equipped with the WebMACS control system, located at the City's Butterworth compost site. Operating on a 21-day retention cycle (1.1 tons/day), the system provides a controlled, reliable composting system that can manage the cities food waste without creating odors, attracting pests or generating leachate even in the harsh winter months.

The Earth Flow supports Grand Rapids' goal of keeping organic resources within the community by enabling the City to process its own collected food scraps locally rather than relying on outside disposal or processing. Its controlled in-vessel environment helps the City maintain consistent composting conditions and produce a high-quality, nutrient-rich soil amendment that can be returned to the community.

With Public Works crews collecting food scraps weekly from secure drop-off bins, the Earth Flow provides the processing capacity needed to connect the City's collection program to its larger circular-economy goals.

100% In-House Municipal Operation: Allows Public Works crews to collect, process, and distribute compost entirely in-house without relying on outside contractors.

In-Vessel Odor & Vector Control: Negative aeration and biofilter system eliminate 95%+ of odors so putrescible food waste (including meats and dairy) can be processed safely within city limits.

Automated Process Tracking: WebMACS automated temperature probes log moisture and heat data to ensure compliance with PFRP pathogen reduction standards.

Scalable Infrastructure: Containerized design allows the City to easily scale capacity as participation expands from 500 households to local restaurants and breweries.