It could be called Schenectady, N.Y.’s version of the “Big Dig.” In July 2007, the New York state department of transportation (NYSDOT) initiated a massive undertaking to repair a 600-yd. (548.6 m) drainage culvert located underneath Interstate 890 near the Michigan Avenue exit.
Now, some eight months and 1,800 ft. (548 m) later, NYSDOT’s crew has pieced together a new steel liner for the rusted out drainage pipe. The tedious task involved twisting thousands of lug nuts by hand onto the bolts that connect one pipe section to another. Then, with the help of an electronic wrench, each bolt was secured into place.
When all was said and done, more than 77,000 bolts were fastened. There were 65 bolts and 5 sections for every 375-lb. (170 kg) ring.
During the entire process the objective was to construct a new liner inside the corroded pipe. For the NYSDOT engineers, it was the first-of-its-kind project in the area.
“We made it up as we went [along],” explained NYSDOT Engineer Bruce Samson, who was inside the culvert for the better part of the project.
In the Beginning…
The gigantic task actually began in November 2006 when the right westbound lane’s pavement started dipping slightly.
“The pipe underneath I-890 was failing badly,” said Dona Frederick, project manager of The Delaney Group, Mayfield, N.Y.
“The road by the westbound lane at the Michigan Avenue ramp was starting to show a depression because all the fines [sand, etc.] were falling through the pipe. The road was beginning to fall, which was why we needed to line this pipe.”
At first glance, the solution appeared to be a simple matter of bolstering the pavement and restoring drainage. Upon closer examination it became obvious there would be no quick fix as evidenced by the old culvert’s condition and the quantity of debris and silt that was present.
The possibility that the culvert was deteriorating became apparent when the pavement sank further.
Due to the seriousness of the situation, the project began immediately as an emergency contract with The Delaney Group.
Going Down Under
The original pipe culvert measured 9 ft. (2.7 m) in diameter and was installed in 1950, a decade before I-890 was constructed. It traversed along the base of the Pleasant Valley Hollow Gorge and channeled a stream that started out near the now defunct Maqua printing company on Duane Avenue. in Schenectady. The outlet was approximately one-third of a mile to the west and down a steep embankment from Norwood Avenue.
Prior to I-890 being built overhead in 1960, a curved section of the original pipe was abandoned. According to NYSDOT records, the section that currently runs beneath westbound I-890 was constructed to connect the two older sections.
The first step called for removing the layers of debris from the culvert’s interior and surrounding outlet. Next, a steep bank that had swallowed a large piece of excavation equipment near the outlet was stabilized.
Nearly 4,578 cu. yd. (3,500 cu m) of soil were removed from the slope and the new bank and streambed were “armored” with sizeable rocks. Once the “outside” work was completed, workers constructed an underground cofferdam to redirect the culvert’s main stream into a temporary pipe that ran parallel to the highway’s westbound shoulder. Pumps also were inserted so the culverts would remain as dry as possible and 100 halogen lights were suspended to illuminate the work area.
Parts of the project called for installing a new concrete floor and spot repairs to fill any holes with cement grout. In instances where the leaks were the worst, an inner pipe was bolted together to line the old pipe. The new, 18-in. (45.7 cm) wide rings consist of five curved steel pieces weighing 75 lbs. (34 kg) each and were secured together within the old culvert. Workers used cement grout to fill in the gap between the old culvert and the liner. Because ventilation on the inside was limited, pieces had to be carried in manually or on carts.
For Frederick and her crew, the pipe’s liner presented their greatest challenge.
“We used a new type of liner that basically is for tunnels,” she explained.
“It [the liner] is a heavy gauge steel provided by Contech. This is the first time we’ve used this particular [product]. In the past, pipes that were in poor condition were lined by inserting a plastic pipe into the old one. Never before have we been in the type of situation where we had to transport it piece by piece and assemble it inside the pipe,” Frederick continued.
What was the crew’s biggest obstacle?
“Water … lots and lots of water,” Frederick said. “From all the water in that area of Schenectady, all of the runoff from storm water. Within that 1,800 feet, a lot of pipes run into this [culvert], which made controlling the water difficult. Several pumps ran inside to keep the water level down within the culvert.”
It is uncertain what the project’s final price tag will be. To date, expenses have topped the $2 million mark and could exceed $3 million by the time it is completed this spring. CEG