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7th Avenue SE Infrastructure Improvements, City of Grand Rapids, Minnesota

2006 Honorable Mention, City Engineers Association of Minnesota

7th Avenue is a heavily used collector roadway located in the City of Grand Rapids’ southeast (SE) quadrant that had been experiencing significant growth for several years. Concerns with traffic on 7th Avenue led the City to complete a traffic study in 2003 that recommended closing several intersections with 7th Avenue and rerouting the most heavily used roadways to a common main controlled intersection. The study recommended the use of a roundabout in the intersection for increased safety and low maintenance costs. An off-roadway multi-use trail to accommodate bicycle, pedestrian, and snowmobile traffic was also recommended.

The growth in the SE quadrant was also impacting the aging sanitary, sewer, water, and stormwater infrastructure. The City’s comprehensive plan called for upsizing the water mains under 7th Avenue to handle the increase in demand and flows.

The City elected to address these comprehensive infrastructure issues by launching the 7th Avenue SE Infrastructure Improvement Project. The project would implement the recommendations made in the 2003 traffic study and bring the area’s infrastructure into line with the comprehensive plan.

The 7th Avenue roundabout constructed at the common intersection of 10th and 8th Streets was the first roundabout constructed and opened for use in the City. The 7th Avenue street and trail lighting system was also innovative. It was designed to save electricity by using approximately half of the lights available (non-intersection) late at night when traffic is low.

A portion of the project was situated immediately adjacent to Lily Lake, where groundwater is approximately 4’ below the surface of the roadway. The proposed utilities (sewer and water) were to be 8 to 10 feet deep. The use of several hundred feet of dewatering pipeline and hundreds of dewatering wells enabled the City to complete the extensive dewatering required to overcome the challenges presented by the project site.