Repairs on the section of Interstate 70 in Glenwood Canyon damaged by a massive rockslide in March were completed last week, ahead of the May 31 deadline set by the Colorado Dept. of Transportation.
Flatiron Construction Corp. of Longmont beat the project completion date, initially set for May 15, but extended to May 31 when CDOT added wire-mesh rockfall netting to the project scope.
Flatiron began the repairs on March 8. Because of the critical need to expedite repairs on the Interstate, the contract carried with it a $5,000-per-day incentive for early completion—with $5,000 deducted each day the work runs past the completion date. The maximum incentive was set at 5% of the contractor’s bid items, which totaled $620,830.
Flatiron Construction earned $31,000 in early-completion incentives by beating the May 31 project completion date by 12 calendar days, according to Stacey Stegman, CDOT spokeswoman.
“I can’t say enough about the efficient, high-quality work that Flatiron has performed,” said CDOT Region 3 East Program Engineer Joe Elsen. “Even with the addition of rockfall netting and some weather challenges, the contractor expedited this project, maintained a safe work zone and delivered a successful project.”
The repairs took place between mile markers 124 and 125, just west of Hanging Lake Tunnel. The work involved bridge deck and bridge wall/rail repairs, including 150 ft of new steel bridge rail; guardrail repairs, about 120 lin ft, to the hillside concrete barrier; median concrete barrier repair, including replacement of 400 lin ft; removal and replacement of 690 sq ft of concrete retaining walls; straightening of steel bridge girders using a flame-straightening process; some lighting and electrical repairs; and repairs to the bike trail below.
Flatiron Construction, with assistance from rockfall contractor Rock Solid Solutions, also installed 14,000 sq ft of wire mesh along a section of the canyon wall near the bottom of the two chutes that delivered the rocks on the March 8 rockfall.
“The wire mesh is designed to keep smaller rocks (less than three ft in diameter) that may release from the talus slope above from reaching the highway,” CDOT Geologist Ty Ortiz said. “The goal is to reduce the chances of these smaller rock incidents; the mesh is not intended to mitigate a large event like the one that occurred on March 8.”
The costs of the rockfall and the repair project totaled $2.2 million and included the rockfall, consisting of $300,000 in maintenance costs, traffic control, blasting/scaling and a helicopter; $1.8 million in construction costs, including the additional $300,000 for the rockfall mesh.
The Federal Highway Administration will reimburse the costs. CDOT is also requesting federal assistance to conduct a follow-up selection study on additional rockfall mitigation in the canyon.
“Rock Solid Solutions worked with us during the incident phase, with our initial scaling and blasting operations, and also with our follow-up work on placing the wire mesh,” said CDOT Glenwood Resident Engineer Roland Wagner. “Their expertise on this incident was invaluable—they deserve a great deal of credit for their incident management and timely response.”