Failure of the new Fort Ann Dam in upstate New York is under investigation by the U.S. Army Corps of Engineers, the New York State Department of Conservation (NYSDEC), the new dam’s contractor and by its design engineer, according to a source familiar with the situation.
Failure of the new dam, which was completed in May, resulted in flooding that destroyed parts of State Route 149 between State Route 91 and U.S. Route 4. Route 149 is a major link between the Lake George region in upstate New York and Rutland, VT.
Shortly after the flooding on July 2, 2005, the New York State Department of Transportation (NYSDOT) called in Delaney Construction of Mayfield, NY, which holds the emergency contract for road repair work in NYSDOT Region 1.
According to Bob Weisgerber, a project superintendent of Delaney Construction, the earth below the new dam gave way between 6 p.m. and 6:30 p.m. on Saturday, July 2. The new dam, upon which work began in September 2004, is located at the south end of mile-long Hadlock Pond.
When the earth gave way, flooding forced the closing of State Route 149, Weisgerber noted.
“We were notified at approximately 10 p.m. on July 2, and had to be at a 7 a.m. site meeting on July 3,” he recalled.
Weisgerber said that while the earth part of the dam, a mixture of clay and gravel, gave way, the sluice way and concrete spillway are still intact.
He explained that the dam holds back the Half Way Brook River, which “crosses State Route 149 four times by zigzagging under the road in four locations, over a four-mile stretch.
“The first area that was affected is located below the dam. The flooding washed out an area of the road 100 feet long, 50 feet wide and 15 feet deep,” he added.
To repair this washed-out portion of the road, Delaney Construction will have to pump grout under the box culvert to re-establish a grout base to hold the bearing load of the box culvert. This box culvert is 60 ft. (18.3 m) long, 25 ft. (7.6 m) wide and 8 ft. (2.4 m) tall.
To perform the required repair work, Delaney Construction will use a Hitachi 330 trackhoe, a Cat wheel loader, and a Cat D5 dozer. Grout-Tech, of Glens Falls, NY, will do the grouting, Weisgerber said. Grout-Tech will use sand and Portland cement. The 35 cu. yds. (26.7 cu m) of grout will be placed using Grout-Tech’s own specialty pressure grouter mounted on a tractor-trailer, he added.
The next affected area, Weisgerber said, is three-quarters of a mile away.
“It consists of a 65-foot to 70-foot long culvert located below the road. Water built up and flowed over the road. As it did, it destroyed the north side of the road, creating a 250 foot long, 35 foot wide and 40 foot deep cavern,” he explained.
The work for this area requires extracting more than 50 oak and pine trees. Donavin Tree Service will use two five-man crews and two cranes to extract the trees. They will use a wood chipper. Trees that are too large for the wood chipper will be loaded on to tractor-trailers and hauled away to be recycled, Weisgerber added.
Once these trees are removed from the cavern, Delaney Construction will build a temporary dirt construction road to the bottom of the cavern. This temporary road will be 250 ft. (76.2 m) long and 15 ft. (4.6 m) wide to allow 20 tri-axle Mack dump trucks filled with gravel to back down into the cavern to begin the process of repairing the road in this area.
Weisgerber said each gravel-filled dump truck will empty the gravel at the bottom of the cavern. It will then be bulldozed into 1-ft. lifts. Then it will be compacted. This work will require the use of three Hitachi trackhoes, two Cat D5 dozers and two Hamm vibratory rollers.
This work will take approximately 10 days, working from 6 a.m. to dark, to complete, Weisgerber said, adding that approximately 9,000 cu. yds. (6,881 cu m) of gravel will be needed to re-establish the road.
The next affected area, he added, is a shoulder that collapsed a half mile from the cavern. The shoulder is 50 ft. (15.2 m) long, 6 ft. (1.8 m) wide and 8 ft. (2.4 m) deep.
“We will dig away the blacktop, haul in gravel, and place it in eight one-foot lifts using a 330 Hitachi trackhoe, a Cat IT 28 wheel loader, a Cat D5 dozer and a Hamm vibratory roller. This work should take about a day to complete,” Weisgerber said.
The fourth affected area is located three quarters of a mile from the shoulder, Weisgerber said. It is a box culvert that was washed away and required immediate attention, he noted.
Here, the east and west sides of the road, 100 ft. (30.5 m) long, 50 ft. (15.2 m) wide and 9 ft. (2.7 m) deep, was washed away, he pointed out.
“We had to excavate mud and debris to suitable soil about nine feet down. Then, we hauled in 3,000 cu. yds. of gravel to re-establish the road. We started this work at approximately noon on Sunday, July 3, and continued the work until 10 p.m. The end result was the re-establishment of the road for one lane of traffic. Then, we came back beginning at 6 a.m. on July 4, and worked until 6 p.m., successfully re-establishing a two-lane gravel road.”
All four areas will get asphalt by July 26, 2005. An asphalt subcontractor had not yet been chosen by press time.
The entire $2-million to $4-million road repair project will have up to 30 people working on the site at any given time, Weisgerber said, emphasizing that Delaney Construction is only repairing the road and is not doing any of the dam repair work.
While at least four separate investigations as to the cause of the new dam’s failure are expected, published reports indicated that the state’s engineers and the new dam’s designer have already been questioned. Published reports also pointed out that the new dam was constructed because the old dam failed to meet new standards established by the New York State Dam Safety Commission.
At press time, no timetable was available as to when the investigations would be concluded and the results made available to the public. CEG