SR 123 emergency repairs
Engineer: Pete Gonzales, U.S. Federal Highway Administration
Owner: U.S. Federal Highway Administration
ABC member: Kibble & Prentice
Record rainfall in November 2006 caused extensive damage all over Western Washington, including multiple washouts along state Route 123, which runs through Mount Rainier National Park and connects traffic from Chinook Pass to White Pass. The most severe washout, at Milepost 11.01, measured approximately 80 feet across at the roadway centerline and nearly 350 feet down the slope.
With only four months in which to complete the repairs, Saybr Contractors was under pressure to restore milepost 10.0 to milepost 11.01, the first task on a multiple award task order contract. The remote location within the national park, 16 miles from the nearest town, was another challenge to this project.
After establishing the grade and clearing the roadway, Saybr built a series of terraces made out of dropped rocks to ease a 65,000-pound excavator to the bottom of the washout. The team trucked in special rock from a quarry 35 miles away in order to recreate the damaged slopes. The rocks were custom blasted from the quarry to meet the Federal Highway Administration's stringent rock mix specifications.
Once on site, the Highway Administration tested the rocks' specific gravity, absorption ratios, durability and sodium sulfate soundness loss. The agency also conducted accelerated weathering tests. In addition, after the National Park Service certified the rocks as weed-free, Saybr had to tarp all loads and pressure-wash each truck as it entered the park to maintain the material's integrity.
The Highway Administration's parameters for the topsoil brought onto the site were even more stringent. After mixing the topsoil with specified percentages of aggregate obtained from designated areas within the state, the soil was tested for specific nutrients.
Environmental measures adopted by the team included using vegetable oil in place of hydraulic oil in all construction equipment; minimizing construction noise by installing special mufflers and tailgate dampeners on all trucks and equipment; and implementing extensive erosion-control measures.
In order to meet the schedule, Saybr worked at several washouts simultaneously and also began rebuilding several culverts that pass under the roadway. A total of eight culverts were rebuilt, with the largest measuring 96 inches in diameter and 90 feet in length. While installing the culverts, Saybr maintained access to each washout site using steel plating.
To repair one mile of ditch that had been scoured by flooding, the team reused all removed material and soil for slope stabilization or stockpiled it on-site in order to maintain the park's soil and vegetation zones, which dictate that soil from a particular elevation has to remain at the elevation where it originated. Finally, the team restored the road surface through grading, placing base course, compacting, placing asphalt and striping the pavement.
Saybr completed the repairs a week ahead of schedule and significantly under budget by using far less material than had been anticipated for the fill. Despite the inherent hazards of this project, Saybr had no safety incidents during the 2,200 hours worked.