IDOT, PTB 195-016: IL 173 and IL 176 Box Culvert Rehabilitation, McHenry County: INTERRA was tasked by the design consultant Bowman Consulting to perform subsurface soil investigations and prepare Structure Geotechnical Reports for box culvert rehabilitations on IL 173 and IL 176 in McHenry County, Illinois. These culverts were originally constructed in the 1930s and 1940s and have severe degradation of the end sections and concrete wing walls. Complete removal and construction of new structures was cost prohibitive. Hence it was decided to remove and replace the headwalls, wing walls and a portion of the barrel. The objective also included extending the barrel by adding an additional section and performing side slope improvements and guardrail improvements. Scope consisted of field inspections, locating and drilling soil borings, laboratory testing and preparation of SGRs. Several meetings and discussions with client were conducted to consider various alternatives and arrive at the optimal solution for each of the structures. INTERRA prepared separate SGRs for each structure Recommendations for wing walls, and barrel extension and construction considerations were included in the reports.

IDOT, PTB 195-015: IL 31 from IL 120 to IL 176, McHenry County: Work for this IDOT project includes the construction of a three-span bridge, 10 retaining walls, 16 box culverts, the addition of one lane in each direction, and the replacement of traffic signals for nearly a seven-mile stretch of IL 31 between IL 120 and IL 176. INTERRA performed geotechnical work involving nearly 250 soil borings totaling 5,000 feet of drilling. Field services include collecting split spoon, Shelby tube samples, bulk sampling for further laboratory testing and classification of soils. INTERRA installed piezometers for groundwater levels. Laboratory work includes moisture content, grainsize analysis, Atterberg limits, organic content, and Proctor testing. Structure Geotechnical Reports (SGR) were prepared for bridges, retaining walls, and culverts. Roadway Geotechnical Reports (RGR) were prepared for additional lanes and traffic signals.

IDOT, PTB 181-005: US 20 Various Improvements, McHenry County: This IDOT project included pavement widening, pavement reconstruction, the construction of a turnabout, curbs, gutters, sidewalk, drainage, two retaining walls, and box culverts. INTERRA scope consisted of Geotechnical subsurface soil exploration which included roadway soil borings, structure soil borings, and pavement cores, laboratory testing, reviewing field data, SGRs and RGR. INTERRA performed Geotechnical analyses and prepared both Roadway Geotechnical Reports (RGR) and Structure Geotechnical Reports (SGR) for the retaining walls and box culverts in accordance with IDOT guidelines.

Other notable McHenry County projects include the following:

  • Local Agency-Allendale Road Bridge SGR, McHenry County, IL
  • Local Agency-Stearns School Road at US 41 RGR, McHenry County, IL