Monroe County Airport (Indiana) engineering services

Project Summary

Hanson provided services to address safety issues brought on by sinkholes at Monroe County Airport in Bloomington, Ind.

Three sinkholes were discovered in 2011 in the runway safety area and along the pavement of the airport’s main runway. It was apparent a long-term and environmentally responsible solution was needed.

Hanson conducted geotechnical and geophysical testing. The data was evaluated, and Hanson presented seven alternatives for repair, which included a recommendation of the method preferred by Hanson’s geotechnical engineers. Hanson then conducted an environmental assessment and topographical survey work.

Hanson designed — on a fast track — the sinkhole mitigation and a rehabilitation of the main runway and taxiways. More than 300,000 cubic yards of earth were removed to the bedrock, identifying any cracks that could potentially become sinkholes in an area that was 1,600 feet long.

Karst “pipes” or holes in the bedrock were covered with a geogrid, a synthetic material that reinforced the soil. Then, sinkholes and potential sinkholes were bridged with 4 feet of a large, shot-rock aggregate, which was covered with a 1-foot-deep layer of crushed aggregate and a geotextile — a permeable, synthetic fabric — prior to replacing the earth. More than 172,700 tons of various gradations of stone were placed.

The airport pursued funding from the Federal Aviation Administration and received a $9.8 million grant for the project. Monroe County and the Indiana Department of Transportation provided funding to cover the rest of the project’s $11 million cost.

Because of the significant economic impact to the airport and its users, the contractor had 68 days to complete the work, requiring a 24-hour, seven-day-a-week construction operation. Nine weeks after the mitigation began, the main runway was in use again.

Hanson also has provided design and construction services for additional projects at the airport:

  • airport roadway and bridge replacement,
  • survey and construction services,
  • hangar development,
  • parallel taxiway construction,
  • perimeter service road design and construction services,
  • runway safety area grading and drainage improvements,
  • taxiway rehabilitation and construction and
  • perimeter fencing.

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