The Grand Forks Regional Airport Authority Board of Commissioners agreed to increase the cost of the County Road 5 project in its meeting Thursday, Oct. 28.
The project, which is covered by ARPA grant funds, was approved for a cost increase of $155,815.80, which is also eligible for complete federal funding as part of the airport’s 2021 grant.
The cost increase comes due to calculations that provided for about 19% shrinkage of the road embankment for the project with a required compaction density of 95%, but a “shrinkage factor” was not taken into account for the ditches.
“When we talk about shrinkage of soil, that is a normal occurrence,” Ryan Riesinger, executive director of the Grand Forks Regional Airport, said. “Some of that was planned for, but in this particular case though, that factor was not presumed for the embankment for ditches being that no compaction efforts were required.”
During the course of the construction so far, it was determined that additional embankment material was needed at the cost of $1.35 per cubic yard for approximately 25,000 cubic yards of excavation. In addition, the topsoil volume for the site was more than in previous estimates, which made for less suitable road embankment.
ADVERTISEMENT
The board noted that determining how much earthwork is needed for projects such as this one is not an exact science due to multiple factors, including including clay or silt that can shrink up to 20% when compacted to 95% density while constructing the pavement subgrade, which is the material underneath a constructed road, which can undergo higher shrinkage than normal due to dry conditions.
Work has already begun to relocate a portion of County Road 5 west of the airport to allow for a in order to expand its east/west crosswind runway. Dirt work has already begun due to agreeable weather this fall, and the paving will occur next year with completion happening during the 2022 construction season.
