Oct. 9, 2008 — After a rockslide in August on the new, cut slope adjacent to the roadbed of the future Christiansted Bypass, Federal Highway Administration officials are meeting this week to determine what to do now. For the sake of safety, work has been stopped in the immediate vicinity of the rock fall but continues elsewhere on the road while geological specialists with the Highway Administration determine how to proceed.
At 2:30 p.m. Aug. 13 a section of rock slid down the bypass embankment into a pile on the roadbed. Contractors working on the job contacted the Highway Administration and local Public Works "probably within minutes of the slide," Doug Hecox, spokesman for the Federal Highway Administration said recently by phone from his desk in Washington D.C.
"Our people are working with the contractors right now and they have done most of the work clearing the area and setting up a buffer zone," he said. "We are meeting tomorrow to work out the method for moving forward. … We are confident the rockslide cleanup and slope stabilization will be cleaned up by the end of this year, probably by December."
While private contractors are doing the actual road construction, federal officials are taking care of the rockslide and slope stabilization at no cost to the territory, under a program called ER or Emergency Relief, Hecox said.
"When there is an emergency or natural calamity, these are funds to help pay for cleanup and work to repair or replace physical infrastructure," he said. "It is 100 percent Federal Highway Administration cost. We pay so states don't have to."
This is the same sort of funding used to replace a highway bridge in Minnesota when it collapsed a few years ago, and to rebuild the Gulf Coast after Hurricane Katrina, he said.
The slide happened where two layers of rock met. The underlying rock is a brittle conglomeration and in this case, "some older and newer rock of the same type slid apart," he said.
The slide occurred right before several weeks of heavy rain and rain played no role.
"There was no rain that day," he said. "Rocks are rainproof. They don't care and are not affected by it. It was purely a geological thing."
The crumbly character of the rock was well known during the planning stages and several standard soil stabilization techniques are already being employed. Drivers near the construction zone can see a row of enormous concrete squares on both embankments. These eight foot squares are bolted 33 feet into the hillside with bolts an inch and a half in diameter. A heavy wire mesh covers the top twenty feet or so of the embankments as well.
Plans call for 130 bolts, each 20 feet long, to be driven into the hillside at strategic spots and for the wire mesh to be extended to eight feet above the ditch adjacent to the roadbed, Hecox said.
While the rock was known to be crumbly, the specific situation leading to the rockslide stems from an unusual interaction between two layers of rock, rather than the general features of the rock and soil.
"The types of circumstances that led to this are pretty uncommon," Hecox said.
If the federal engineers on-island now determine the slope remains unsound, some highly specialized geological experts with the administration will be flown in from Hawaii and Washington state to examine the situation in person, but that may not be necessary, he said.
Will it delay the bypass?
"This puts the schedule a little behind, but not so far that it will be a huge issue," Hecox said. "I'd be really surprised if it turns into a big headache."
A contractor at the worksite who asked not to be identified said the project is actually slightly ahead of schedule so far. Several calls over several days to officials at Public Works asking for comment were not returned. Construction began on the road last May. (See: "Three Decades Down the Road, Work Begins on Christiansted Bypass.")
The project, which has been in the planning stages since 1975, is aimed at relieving traffic congestion, improving safety and restricting large vehicles currently through the downtown Christiansted area. The 1.2 mile road will begin at the existing Contentment Road and follow east to end at the intersection of Hospital Street and East End Road and Mt. Welcome Road. Plans call for construction of two 12-foot lanes, paved shoulders, a climbing lane on the east end, sidewalks and curbs along the north side, streetlights and traffic signals. It is fully funded by the Federal Highway Administration. The project is to be done in three separate sections, with three separate, consecutive contracts. Phase one, scheduled to be concluded sometime late in 2009, includes excavation, drainage structures, erosion control, soil stabilization such as described earlier as well as planting vegetation. V.I. Paving is the principal contractor for phase one, having bid $6 million for the job late in 2006.
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