The Glen Road (T.H. 61) project provided the citizens of Newport, Minnesota, with access to the reconstructed T.H. 61. Deep soil mixing was planned to improve all foundation soils. CNA Engineers, together with C.S. McCrossan and American Engineering and Testing (AET), developed a value engineering plan to limit the use of deep soil mixing to critical zones, and implement soil replacement elsewhere.
We developed a quality control/quality assurance program to ensure that deflections of the foundation soils would not exceed the project requirements. Our firm used GPS-based record keeping, providing a permanent electronic record of all the data. Modeling by CNA Engineers and AET of the subsoil reactions show that the fill material will exceed the performance requirements established by Mn/DOT.

Quality Control Testing included, 402 stiffness tests using the Humboldt GeoGauge, 21 sand cone density tests and 44 small-scale plate load tests. The Quality Assurance Testing included 63 dynamic cone penetrometer tests, 10 cone penetrometer soundings and 15 pressure meter tests.

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Reconstruction of the I-494-Highway 100 interchange located in the southwestern area of the Twin Cities required soil retention for temporary construction stages. The southeast quadrant of the interchange required construction of frontage roads, entrance ramps and mainline roadways through and immediately adjacent to wetland areas, including creeks. Some of the problems our engineers encountered on this project were: soil conditions were different than encountered during the preconstruction site investigation, subsurface obstructions that prevented the driving of sheeting to the design depth and very deep organic soils.
We managed the site investigation and design work, performed soil analysis for the design of retaining walls and soil removal, produced construction drawings, determined design standards and observed subsurface conditions.

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