Imagery Videos Photos City of Duluth: Lower Michigan Street Gas Main. The gas main has been relocated because it was in the way of new bridge and wall foundation construction for the Twin Ports Interchange project. City of Duluth: Sanitary Lift Station. The lift station is being relocated because it is in the way of the new bridge. MnDOT has three billboards located in Minnesota and Wisconsin, reminding travelers of our upcoming Twin Ports Interchange project. The challenge is that we have very poor/weak soils in this area. Much of it is old filled in bay. To transfer the load of the fill we plan to place to a solid underlying material, we are placing "ground improvements,” which is basically a grid pattern of 16" grout columns inserted into the ground to a hard layer. This will support the eventual roadway fill. There are grout columns under the fill holding it up. The fill is reinforced, that is why it is so blocky. We needed to keep it narrow because we did not have much room to work now. The entire installation is instrumented for settlement and we are also looking to see if the ground improvements are moving any soil laterally. We don't want to be putting pressure on existing bridges and utilities. MnDOT is testing the process to validate our design and perhaps make it more efficient. We cannot afford to have settlement when we are done. Earlier this summer (2019), crews completed work at the corner of Railroad Street and Garfield Avenue in anticipation of the Twin Ports Interchange project. Crews made improvements to several local streets, including Garfield Avenue and Railroad Street, to carry extra traffic once the Twin Ports Interchange project begins.