The Minnesota Department of Natural Resources (DNR) is facilitating the multi-year, $18-million Kingsbury Bay – Grassy Point Habitat remediation and restoration, a site located in St. Louis County, Minne - sota. The goal of the project is to restore 240 acres of fish and wildlife habitat within a part of the St. Louis River Area of Concern (AOC). Critical to the project is to excavate and reuse excess sediment, remedi - ate and reuse legacy wood waste and remove non-native vegetation. Minnesota DNR contracted Barr Engineering Co. to manage the en - gineering and design, construction administration, and quality control oversight and Veit & Company, Inc. for the construction effort. Begun in 2019, the restoration effort includes: • The removal of invasive cattail from Kingsbury Bay to an offsite disposal location • The removal of legacy wood waste from Grassy Point and reuse of waste to construct small islands in the area • Sediment dredging from Kingsbury Bay and reuse of sediment to restore aquatic and upland habitat The Veit crews also installed in-water stream control structures at the inlets of Kingsbury and Keene Creek, with a little help from technology. Underwater Visualization Founded in 1928, Veit & Company, Inc. has long been a technology leader in the Upper Midwest’s site prep and civil works market seg - ment. Its technology-enabled fleet includes dozers, excavators, motor graders, and skid steers all equipped with 3D machine control systems, as well as rovers, base stations and total stations—all connected to the cloud, enabling the easy transfer of 3D project files to field crews. For the Kingsbury Bay – Grassy Point Habitat project, GPS-guided machine control on excavators was particularly valuable, especially when combined with a Trimble Marine Construction System to track underwater material removal in real time. One of the most challenging tasks in the marine construction environ - ment – whether for dredging, building, or demolition – is working in turbid water including suspended sediments and materials, making it impossible to accurately monitor progress. Conventional practice is for a contractor to estimate the approximate amount of material to be removed or placed on a given site based on experience and pre- construction hydrographic surveys. Once the operator has reached an estimated point of completion, they conduct a post-construction survey for verification and certification, and almost always, the operator must return to the site for rework. The Trimble Marine Construction System can be integrated with a Underwater Visualization Drives Timely, Successful Habitat Restoration Project
single beam echo sounder (SBES) to acquire pre-/post-dredge survey data from below the water and then quickly identify high and low spots, calculate progress volumes and send grid model updates to both the office and the dredge vessel. “We use the Trimble Marine Construction System to track the bucket location in real-time in 3D—a huge advantage in water,” said Britton Lawson, Director of Construction Technology at Veit. “Essentially, the 3D map created by Trimble is the only eyes for the excavator operators to know where they’ve been and where they need to go. Project manag - ers are also able to track progress and material quantities moved.” Dredged with Accuracy For the Grassy Point job, Veit used two Liebherr excavators with clam - shell buckets on barge spreads. Each was equipped with the Trimble Earthworks Grade Control Platform using the Minnesota Department of Transportations’ MnCORS VRS Virtual reference station network for instant access to RTK positioning services. “One machine would excavate to design and load the material. Two tugboats moving four hopper barges were used to transport the material
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June 2021
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