Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/894232
EquipmentWorld.com | November 2017 65 Eventually, on September 6, TxDOT and HCTRA crews could start pumping. After 22 hours, the water was gone from the roadways, and the damage could be assessed. Fortunately, the sinkhole was not directly under the frontage road, which is elevated above the tollway. The hole had opened about 20 feet deep and 50 or more feet long in a grassy area by the road's retaining wall. Below the frontage road, though, the tollway's south- bound lanes had buckled and were raised about 4 feet. The lanes are in a depressed area that had been fi lled with an estimated 70 million gallons of water. What engineers didn't know until the pumping ended was that water had also been rising underneath the toll road. "The water had so much pressure, it was actually shooting up through the longitudinal joints in our pave- ment in the depressed section," says John Tyler, HCTRA deputy director of engineering. "It was just an incredible amount of pressure coming in that hole." That left a fi ve-lane section about 650 feet long in the southbound tollway lanes needing excavation and replacement of both the base and pavement. At fi rst, HCTRA engineers thought the drainage sys- tem under the road might have failed. So they desilted the drains and ran cameras down the lines. No damage was found. The next concern was making the area safe for work- ers. The retaining wall on the above frontage road at the sinkhole had to be shored up. "We're working up above; they're working down below," says Karen Othon, public information offi cer for TxDOT's Houston District. "We had to place bracing on the retaining wall from down below on the toll road fa- cility so that any of the work that we were doing would not cause any safety hazard to the people that were working down below." 'We worked day and night' Less than three hours after the 6:30 a.m. call, Harper ar- rived on the site with equipment and crews ready to go to work. He found a crowded scene with TxDOT and HCTRA staff, a TxDOT contractor and another HCTRA contrac- tor. The transportation agencies had called on contractors working on other projects for them and issued change or purchase orders to speed up the road-repair process. Harper soon learned the job had changed. Harper Brothers would not be fi lling the sinkhole. That would be the responsibility of the TxDOT contractor, Williams Brothers. By virtue of having its subcontractors on site fi rst, Harper Brothers' job would be to secure the tollway's side of the retaining wall and tear out the damaged pave- ment and road base on the tollway. His crews would prepare the section for the other HCTRA contractor, ISI, to replace the concrete and complete the roadwork. Up above at the frontage road site, Williams Broth- ers had cut into the pavement and determined that no damage had occurred beneath that road. Its next task was to fi ll in the sinkhole, but it had to do so in stages. This 20-foot- deep sinkhole formed beside the Beltway 8 frontage road just above the Sam Houston Tollway. Source: TxDOT Source: TxDOT Tropical Storm Harvey fl ooded a section of the Sam Houston Tollway West and a Beltway 8 frontage road at Boheme Drive for nearly two weeks. A sinkhole had also formed beside the frontage road. (The sinkhole can't be seen in this photo, but it is located just behind the white truck in the left background.)