Bruce Samson’s silhouette faded as he stepped further into the dimly lit tunnel nearly 40 feet below the earth.
His feet splashed in the ankle-deep water as water trickled in from various areas of the subterranean chamber. Daylight gave way to dim illumination from a string of overhead halogen bulbs with each step he took into the dank underworld.
“What you see ahead of you is all six lanes of Interstate 890,” said Samson, the state Department of Transportation construction inspector-turned urban spelunker, during a recent tour of the passage.
For more than a year, Samson and dozens of workers from the Mayfield-based Delaney Construction have labored in a failing culvert that carries a 1,800-foot-long segment of what was once the Brandywine Creek. Originally installed more than six decades before the construction of I-890, the cavernous culvert had deteriorated in many areas, causing sinkholes under the highway overheard.
When two of the highway’s westbound lanes buckled in late January 2007, state officials initially thought they could solve the problem by cleaning out the stream bed and reinforcing the culvert with an ordinary pipe liner. But after more a year on the job, they’ve found there’s nothing simple or ordinary about the project, which is expected to continue through April and has required more than $3 million in funding.
“What started out as a simple pipe cleaning turned into a pretty major project,” Samson said.
The Brandywine was one of four significant streams that once flowed freely through Schenectady. Originally, the small waterway fed what was called the Brandywine Pond and then meandered west through a popular hollow called Pleasant Valley, one of several sites once considered for a main city park during the early 1900s.
The creek traveled through the wooded vale opposite the former Maqua Company printing plant — now the headquarters of SuperPower Inc. — off Duane Avenue and Altamont Avenue and toward Broadway several miles away. Part of the stream was channeled through a culvert by the plant so that small thoroughfare could extend from Michigan Avenue to Broadway.
I-890 is born
During the late 1950s, state officials unfolded plans for I-890, a spur connecting to the recently constructed Thruway to accommodate massive commuter traffic from General Electric and American Locomotive Company plants in Schenectady. The project sent a significant portion of the nine-mile highway through the middle of Pleasant Valley, including over the top of the original Brandywine Creek bed.
Portions of the old culvert were extended so that the stream could be carried under I-890 and underneath the eastbound exit to Norwood Avenue. After the new section of culvert was in place, it was buried beneath nearly 40 feet of fill.
“As cars and trucks whiz through that section, it’s hard for old-timers to recognize what used to be a wonderful place to go for childhood adventures,” lamented Larry Hart, Schenectady’s former historian, in a Daily Gazette column published in 1999.
Today, the Brandywine is a small, fetid waterway that catches storm sewer runoff from the city’s Mont Pleasant and Hamilton Hill neighborhoods and trickles it down toward the Mohawk. The creek is considered a Class C waterway and is occasionally monitored by the state Department of Environmental Conservation, but not regulated.
“It’s an urban waterway pretty much,” said DEC spokesman Rick Georgeson.
Problems with the I-890 culvert were first noticed in November 2006, when DOT inspectors noticed parts of the right westbound lane had dipped. State officials launched an emergency project several months later after the adjacent lane also began to tip, prompting concerns the ailing culvert could cause a collapsed of the highway.
DOT crews initially figured the sagging highway was a result of the culvert being choked with debris. Workers created a coffer dam beneath SuperPower’s parking lot to divert the Brandywine’s normal flow into a storm drain several hundred yards down I-890, so that the length of the culvert could be cleared.
But when state contractors began clearing debris from the mouth of the culvert along Norwood Avenue, the hillside gave way and buried an excavator beneath tons of soil. Though no one was injured, workers were forced to remove 3,500 cubic meters of soil and import more than 7,000 tons of rock to stabilize the hillside before work inside the culvert could commence in May 2007.
Meanwhile, the steady flow of the Brandywine was stopped with a coffer dam created beneath SuperPower’s parking lot. Creek water was diverted along a stretch of I-890 and into a storm drain so that workers could slowly begin hauling out the tons of debris that had accumulated in the ailing pipeline.
In all, Samson said roughly five dump truck loads of silt, rock and debris was removed from the passage — all by pail. Though workers found everything from bicycles to BB guns in the pipe, he said nothing that unusual turned up.
“No .38s, no body parts, nothing like you’d expect to find 40 feet in the ground in Schenectady,” joked Samson.
What they did find, however, was that the culvert’s convoluted path would prevent them from extending a solid 7-foot-wide liner to reinforce deteriorating areas. Instead, contractors had to assemble the liner piece by piece, 18 inches at a time throughout the culvert’s 1,800-foot length.
Further complicating matters was that the pieces would need to be hauled into the culvert and assembled by hand. With little ventilation inside and few outlets to the world above, operating gas-powered machinery would have created a lethal situation in the tunnel; the sharp, galvanized metal edges from each segment also made it impossible for workers to use wheelbarrows.
So from early summer to late December, three-man crews hauled each of the five pieces needed to create a 375-pound ring into the culvert. Once there, they used electric drills to tighten the 77,000 bolts that now hold the rings together.
Workers then filled the space between the old culvert and new liner with mortar, bracing the ground from collapsing into the tunnel. Samson said even that proved to be more complicated than anticipated, after the mortar began leaking into the tunnel through small cracks between the rings.
As with many challenges presented by the bizarre underground environment, crews brainstormed and came up with an unconventional solution. Each leaking area was coated with spray foam insulation, which plugged the small cracks long enough until the mortar could dry.
“We make it up as we go,” Samson said. “Every day we find some new trick that works better.”
Rain doesn’t help
The arduous work inside the culvert is compounded by the circumstance outside. Even with the Brandywine diverted, a moderate rain storm can cause the tunnel to become inundated with runoff and debris.
Samson said a half-inch of rain on the surface will nearly fill the culvert, sometimes making work impossible for days. After every significant rain event, he said crews also need to clear volumes of debris washed into the culvert from the surrounding neighborhoods; even the halogen lights hanging overhead are sometimes broken by storm runoff hammering through the tunnel.
“A rain event Wednesday, and we could lose the rest of the week,” he said.
Yet few I-890 motorists are aware of the herculean effort literally taking place beneath their wheels, said Pete Van Keuren, a regional spokesman for the DOT. Delaney’s small work trailer is unobtrusive off the Michigan Avenue exit and there are usually fewer than 10 workers on site at any given time.
Since the inception of the project, Van Keuren has fielded a steady stream of calls from irate drivers wondering why a construction zone remains on the highway, even though there appears to be no work being done. The calls have diminished somewhat since the DOT lifted their speed zone and reopened both lanes.
“But when motorists are going over I-890, they really don’t know what’s going on 40 feet down,” he said.
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Categories: Schenectady County