Gas pipeline cause of I-70 sinkhole west of Rifle
RULISON, Colorado ” A large sinkhole discovered Wednesday evening in the eastbound lanes of Interstate 70 just east of the Rulison exit was caused by a water-filled void around a Williams Production gas pipeline running under the highway, crews determined on Thursday.
Work to repair the sinkhole resulted in a detour of the eastbound lanes onto Highway 6 from Rulison to the West Rifle exit until late Thursday.
Both eastbound lanes were to open by 7 p.m. Thursday, but the left lane was to be closed again today to allow further work, according to Colorado Department of Transportation regional spokeswoman Nancy Shanks.
“This single-lane closure may be necessary during the daytime hours into next week,” Shanks said. Motorists should check CDOT’s traveler information website at http://www.cotrip.org for the latest closure information.
The depression was discovered by CDOT Region 3 maintenance crews about 7:20 p.m. Wednesday, just east of mile marker 81. Traffic was soon detoured onto Highway 6 between Exit 81 at Rulison and Exit 87 at west Rifle.
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“The hole was about 6 feet in diameter and 8 inches deep,” Shanks said. No accidents resulted from the sinkhole.
The hole was excavated overnight to approximately 35 feet in diameter and 8 feet deep, enabling crews to examine the subsurface and ensure there were no other voids.
On Thursday, crews from CDOT and Williams Production, a gas company operating in the area, drilled four bores into the westbound lanes above a 20-inch diameter gas pipeline that was laid 20 feet under the roadway in February, to determine if the line was the source of the voids.
“I can’t say enough about Williams’ responsiveness to this incident,” said Mike Verketis of CDOT’s Region 3 utilities branch. “Even before the source was confirmed and the road was closed, Williams crews were on scene with manpower and equipment, even for the paving operations; nothing was spared.”
Williams Production will use high-pressure grouting equipment to fill the voids surrounding the pipeline with a type of “light concrete,” according to Williams spokeswoman Donna Gray. The pipeline runs approximately 400 linear feet under the interstate.
“The bore was drilled in January before the pipeline was installed,” Gray said. “We’re still investigating what caused the void, so we really don’t know what the direct cause was yet.”
The pipeline was installed to collect gas from the Rulison area and take it to a processing plant on Parachute Creek.
“It has not been pressurized yet, so there was no gas running through it,” Gray said. “We were out there from the very beginning working on it.”
Shanks said Williams has agreed to bear the cost of the highway repairs.
“We still have some work to do on it,” she said. “They patched the roadway, and now the goal is to mitigate the area so it does not happen again.”
Shanks said it was fortunate the sinkhole happened where it did so that a detour could be easily established.
Contact John Stroud: 384-9160