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Roseville Public Works, Environment and Transportation Commission Agenda Item DATE: May 27, 2025 ITEM: 5.a. ITEM DESCRIPTION: Ramsey County Ditch 4 Construction Soils Study Update Background In 2021, Roseville converted an open ditch into a buried pipe that carried water north towards Oasis Pond. The project helped the City improve the area for development, created a pathway connection between County Rd C and Terrace Drive (and future connection to Oasis Park), improved water quality by reducing erosion, and also helped lower high water levels of upstream ponds. The area adjacent to the pathway was seeded with a native shortgrass prairie seed mix that will help improve habitat for pollinators, reduce soil erosion, and will require less inputs than turf grass. During the project, staff met with Alliant Engineering to discuss the possibility of doing a study to look at the soil after a construction project has been completed. The goal of the study was to see if soil health could be improved by topdressing compost over the site. Compost has the ability to retain moisture, be a slow - release fertilizer, improve soil structure and improve drainage, allowing plants to root deeper and help reduce erosion potential, and also sequester atmospheric carbon. By topdressing in the fall, the freeze/thaw cycle would slowly incorporate the compost into the sandy construction soils, and improve the overall health of the soils. The study started in 2022 in partnership with Alliant Engineering, Ramsey County Environmental Health, Ramsey/Washington Recycling & Energy and the City of Roseville. Alliant created a plan and schedule that included soil borings and infiltration tests over a control area and several blocks of area adjacent to the pathway. Alliant also scheduled volunteers to spread the compost and had invited young professionals to attend the event as a way to have some hands-on experience and talk to local scientists and engineers in their field of interest. Ramsey County's partnership included the delivery of 10 cubic yards of compost (from their food scraps collection program) at no cost and also provided $4,000 towards the cost of the study. The City of Roseville helped by providing the site, coordinating volunteers, providing tools and equipment, as needed, throughout the process. This study was presented at numerous conferences, and we received an Honor Award from the American Council of Engineering Companies, Minnesota Chapter, on February 23, 2024. Now, after a few years of data collection, staff can present an update to the Commission on the findings of the ongoing research. Recommendation Receive presentation from David Bauer, Alliant Engineering. Attachments None Page 17 of 88