—by Kathryn Tempas
I’ve often wondered what happens to the leaves and shrub trimmings that I take to the yard waste collection site off Pierce Butler. Sometimes the piles are very small, other times mountainous. Do they become the composted soil that you can get in the spring at the sites? What about that big brush mound in the back? What is its fate? I decided to get to the bottom of the pile, and found my way to John Springman, Ramsey County Environmental Health Supervisor, who gave me a wealth of information that I gathered, composted, and will return to you.
Composting of yard wastes is a popular service provided by Ramsey County. The seven yard waste sites register 430,000–450,000 visits per year. They are open five days a week (MWFSS), April to November, with limited days and hours December to March. They accept leaves, grass clippings, non-woody plants and trees and shrubs, but no stumps.
Leaves, grass clippings, and soft plants
Ninety percent of the soft plant material is hauled to private composters, such as Gertens and Creekside Soils. One site in Ramsey County processes the leaf/grass material on site because they have the space available. Other sites just don’t have room to hold 11,000 to 12,000 cubic yards of material as it “cooks down.” The one site in White Bear Township that can handle the material uses windrow composting to help the leaves, grass, and soft plants degrade. This involves long rows of material (7 feet high x 18 feet wide x several hundred feet long ) that are turned once a month to facilitate aeration and faster breakdown. In the process, 12,000 cubic yards are reduced to 4,000 cubic yards. The finished product from this site is divided among the other sites and is your compost available every spring.
According to Springman, Ramsey County is currently in the planning stages of adding collection containers for organics at the yard waste sites next spring. The containers would be available to residents to drop off food scraps and other organics such as non- recyclable paper. Stay tuned.
Trees, shrubs, and branches
Tree and shrub trimmings that you take to the yard waste site follow a different journey. When the pile gets to a certain size, the materials are put through a tub grinder and hauled to the St. Paul Wood Recycling Yard. From the wood yard, the wood mulch is trucked to District Energy, a power plant located in downtown St. Paul (www.districtenergy.com/inside-district-energy/history) This power plant once burned coal, but was retrofitted to burn wood mulch, a more renewable source.
Keeping the wood in St. Paul helps prevent spread of the emerald ash borer, as we cannot ship wood products out of Ramsey and Hennepin counties, which are under quarantine. Up to 50 semi loads of wood mulch a day fuel District Energy. Excess energy production is sold to Xcel Energy. Burning the wood mulch generates heat, which heats water needed downtown, and the steam generated provides electricity.
Remember that compost sites are not open every day. The reason is that on those other days, materials are moved along on their journey. Private composters may be moving materials using their large trucks, or the tub grinder might be reducing that pile of shrubs and branches so it can be moved to District Energy. For safety reasons, it’s best to not have the public around when these heavy machines are in use. We can be thankful that Ramsey County is providing this useful service to our community.
[Kathryn works part-time at the co-op and is a regular newsletter contributor.]