A day of torrential rains washed out four lanes of Dale Boulevard in Northern Virginia May 12, sparking the Virginia Department of Transportation into awarding emergency contracts for its repair.
David Brown, VDOT’s maintenance program manager for Prince William County, said the heavy rains seeped into the earth below the roadway from a storm water management pipe, causing the bank to soften, which eventually led to the failure of the roadway.
“It washed out the road from the bottom, up,” he said.
The storm water, Brown explained, “took the path of least resistance” through the fill.
In the rain’s wake, a 20-ft. deep by 25-ft. wide breach in the roadway remained.
By design, many storm water management systems in the county use embankments as dams. Brown said that led to the Dale Boulevard washout. VDOT staffers now will reassess areas with this design to determine how it impacts the roadways and how downstream areas would be affected if storm water was allowed to flow past the dam.
“We have to strike a delicate balance between the management of water and the preservation of roadways,” Brown said.
VDOT crews responded with a pair of excavators to remove all of the mud and loose debris in the ditch and to enlarge the opening to nearly 100 ft. across at the top so crews could easily access the 120-in. concrete storm pipe. The excavators had to maneuver around a 10-in. gas main, a 15-in. storm drain, as well as numerous electrical and communications lines, Brown said. The work was completed under the supervision of Superintendent Steve Satterwhite.
Once the ditch was cleared, crews determined the storm pipe had only suffered minimal damage and did not need to be replaced. Brown said the pipe had settled at a couple of the joints. Crews from E. Ann Jackson Inc. put a sealer at each joint and cleaned out silt that had settled inside the pipe. Grouting the pipe will prevent any future leakage into the ground under the road and help prevent future undermining, Brown said.
As soon as it was determined the pipe didn’t need to be dug out and reset, backfilling operations began. Crews were able to use some of the excavated material they had saved at the job site and the remainder was filled with 21A. Approximately 5,300 tons of backfill was needed to fill in the washed out area. Brown said crews achieved 92 percent density.
To shore up the roadway even more, crews also placed rip rap on the upstream side of the embankment.
The trench was topped with 10 in. of base material and was capped with a 1.5-in. temporary surface mix to allow traffic to flow just 15 days after the washout.
Timing was important on this project, as Dale Boulevard is a heavily used commuter route, carrying 26,000 vehicles per day. The washout was only 4 mi. away from the road’s interchange with Interstate 95.
Brown expected a permanent surface would be completed by mid-June. Crews were to mill past the original construction joints when they prepared to overlay the area with the fresh course of surface material.
The excavation was completed by VDOT’s Prince William County state force construction crew, who rented trucks, a Gradall, two excavators and two rollers for the job. D&F Construction completed curb and gutter work and Branscome Paving completed the asphalt work. Penn Line installed several hundred feet of guard rail.
The crew from VDOT’s Lake Ridge maintenance headquarters assisted in the job by setting up and maintaining the detour around this site.
All four contractors called in for the emergency project were already under contract on nearby VDOT projects, Brown said. Emergency projects do not need to go through the public bidding process; contractors are selected based not only on cost, but also on how quickly they can complete the project.
In total, the job cost approximately $400,000.
“With a washout of this size, it took a lot of teamwork to pull this together, but the crews did an excellent job and we are happy to return the road to the motorists,” Brown said. CEG
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