WESTMINSTER, Colo. — CDOT said it is not sure how much it has spent so far of the estimated $20 million cost to complete the US 36 rebuild project following the highway's collapse in July.
The eastbound lanes of US 36 between Wadsworth Boulevard and 104th Avenue/Church Ranch Boulevard had been closed since July 12 after a crack on the highway quickly turned into a sinkhole. CDOT reconfigured traffic to allow two lanes of eastbound traffic on the westbound side in that area while crews worked on a more permanent solution.
On Friday, all lanes of US 36 were reopened.
The cost of the US 36 restoration, as well as the impact on traffic and discussions to assess other highways' structures were among several questions 9NEWS asked during a project site tour Friday morning.
Kurt Kionka, a resident engineer at Colorado Department of Transportation (CDOT) and the US 36 project manager, said the use of geofoam to rebuild the wall helped take the weight off the wall. The old backfield weighed 130 pounds per cubic foot, whereas the geofoam weighs 2 pounds per cubic foot.
WATCH: What's with the foam on U.S. 36?
In July, CDOT estimated the rebuild project would cost $20.4 million. Kionka said it is unknown how much the project has cost so far.
"We're still actively out here in construction, and we don't have a total cost yet," Kionka said.
CDOT said Colorado highway has walls similar to those along US 36. Kionka said there has been discussion about checking all the other areas up and down the corridor.
"This whole [US 36] wall was designed considering the worst-case soil conditions under this wall," Kionka said.
One worst-case soil condition Kionka mentioned?
"Fat clay that is absorbed moisture," Kionka added.
An ongoing forensic investigation to answer what exactly caused the collapse will be revealed after its completion.
"We're doing a forensic investigation that is still ongoing. I think when that is completed and the report is produced, then I think those questions will hopefully be answered more to the cause and the ultimate responsibility you know if that is something that the report shows," Kionka said.
CDOT will continue working on remaining aspects of the wall in the upcoming months.
RELATED: Who's in charge of inspecting US 36?
Kionka said a precast panel facade will be added to the front of the wall so it is at full height and the bike path will be restored to its original condition.
The median barrier will be replaced after it was removed to put the eastbound lanes over on the westbound side over the last couple of months, Kionka added.
CDOT will complete additional work on the wall, bike path, and a fence, with an estimated completion date of December.
SUGGESTED VIDEOS | Local stories from 9NEWS