1NE Watershed Planning & Preliminary Design, BMPs, Reconstruction, and Storm Sewer Improvements

The Mississippi Watershed Management Organization (MWMO), in partnership with the City of Minneapolis and Minneapolis Park and Recreation Board, retained SRF to study the 2,000-acre 1NE Watershed to solve flooding, improve water quality and improve ecological habitat. We evaluated different watershed improvements, including adding new infrastructure, installing stormwater BMPs or green infrastructure, and modifying stormwater management techniques on City, MPRB and railroad-owned properties, along with enhancing habitat along key corridors within the watershed.

SRF and the project partners developed and evaluated a list of project options to quantify potential benefits. SRF developed 30% construction plans and cost estimates for the preferred scenario that is a combination of improved storm sewer infrastructure improvements, flood storage and water quality BMPs within Columbia Park and Golf Course, distributed green infrastructure, and ecological restoration plans. SRF’s collaborative approach to stakeholder engagement provided the backdrop for the consensus-building and framework developed for the partners to work together to identify projects that met the varying goals and that quickly moved into final design and implementation.

This project successfully led to receiving an $800,000 Clean Water Fund Projects and Practices Grant from BWSR and an $100,000 Natural Resources Opportunity Grant from Hennepin County. The planning project resulted in three construction projects: Hoyer Heights Neighborhood Street Reconstruction, 35^th Avenue NE and Tyler Street NE Stormwater Improvements, and Northern Columbia Golf Course BMPs.

Hoyer Heights Neighborhood Tree Trenches. The Hoyer Heights neighborhood is within the 1NE Watershed and experiences flooding during large storm events. The City of Minneapolis retained SRF to complete a feasibility study on implementing storm sewer improvements and tree trenches in conjunction with the planned neighborhood street reconstruction project. This led to the final design of storm sewer improvements and implementation of tree trenches on three streets as a pilot project. SRF also assisted the City in obtaining MWMO grant funding to install the tree trenches as a water quality improvement.

35th Avenue NE Stormwater Improvements. One of the 1NE Watershed preliminary design projects was reconstruction of existing trunk storm sewer on 35th Avenue NE and Tyler Street NE to relieve flooding in several neighborhoods. The City of Minneapolis retained SRF to complete final design of the trunk storm sewer improvements and associated street restoration. SRF completed survey, XP-SWMM modeling, and design of storm sewer, street, and ADA improvements. The new, larger storm sewer connects to the storm sewer and BMPs within Columbia Park and Golf Course. The project also included design of a 12-foot diameter hydrodynamic separator to provide removal of total suspended solids prior to discharge of stormwater runoff to BMPs in Columbia Park and Golf Course.

Northern Columbia Golf Course BMPs. The 1NE Watershed Planning and Preliminary Design project included preliminary design of several BMPs and improved storm sewer connections in Columbia Park and Golf Course to provide improved water quality treatment, reduce flooding in neighborhoods and the golf course, and enhance habitat and ecological function. The MWMO retained SRF to complete final design and construction administration of the Northern Columbia Golf Course BMPs project.

The project reconstructed an existing wet pond in the northeast part of the golf course, constructed a new dry basin at the multi-use athletic field in Columbia Park and a new infiltration basin in the northwest corner of the golf course, installed a new trunk storm sewer to convey stormwater from Central Avenue across the golf course and park, and included native plantings to restore 19 acres of habitat throughout the golf course and park. The SRF team developed final design, XP-SWMM and P8 modeling, flood inundation and water quality mapping, contractor-style estimating, and construction plans for the project.