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NEW THREE PIPES BRIDGE IN PLACE

By Warren Cobb
Community Editor

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three pipes bridge west ashley greenwayWorkers make the final placement adjustments to put the prefabricated steel bridge in place. When the work is finished, planned for later this month, the span will re-complete the nearly 10-mile stretch of the West Ashley Greenway. The project also enabled the City to complete an erosion control project in the marsh

A lengthy section of the West Ashley Greenway from Croghan's Landing to Main Road has been closed for the past several months after the erosion around the so-called Three Pipes Bridge became so bad, the wooden bridge nearly washed away. Last week, contractors with the City of Charleston put in place the new Three Pipes Bridge. The 100-foot steel deck span is a shining new amenity to the Greenway, and one that the City of Charleston hopes will provide recreation and transportation opportunities for decades to come.

The West Ashley Greenway is a linear park that runs along an old railroad track from Albemarle Road to Main Road, approximately 10 miles. The original Three Pipes Bridge was a wooden structure built over three large drainage pipes about three-quarters of a mile from Croghan Landing Drive. The ebb and flow of the surrounding marsh has caused the dry land around the area of the bridge to erode on a massive scale. The City of Charleston had been looking to undertake erosion control measures in the area for some time. A few years ago, City officials noted the bridge was beginning to be unsafe, due to the amount of the erosion on both banks of its footing.

The City lucked up when it was able to obtain about $150,000 from the Federal government through a Recreational Trails Grant. Another $125,000 was obtained through a grant from the National Oceanic and Atmospheric Administration (NOAA) for erosion control.

"The erosion was significant," says City of Charleston Parks Department deputy director Matt Compton. "We needed to stop that so marsh wasn't further deteriorated. Once erosion starts and you don't stop it right away, it will take your trail. Over the years, we've done some stopgap measures. But the NOAA grant allowed us to do it and do it well."

The new bridge was manufactured in Alabama and shipped to Charleston. The steel structure weighs several tons, and had to be brought in on a barge. At high tide in the middle of the night on March 2, two cranes-one on either side of the Greenway-heaved the bridge into place on top of the pre-poured footings.

The span of the Three Pipes Bridge has been extended from about 42 feet to 120 feet. This not only allows for a more impressive structure and piece of architecture along the Greenway, it also allows more water flow underneath the bridge, thus easing the pressure of the water on the bank and slowing erosion. The banks of the two sides of the bridge will be covered with "ArmorFlex." ArmorFlex is flexible, interlocking, compressed, concrete blocks of uniform size, shape, and weight used for erosion control. The blocks have openings, which will allow for vegetation to grow within it, which will also enhance erosion control.

Compton discussed the project in terms of how it enhances the City of Charleston. "It's a pretty intensive project over there," he says. "We view it (the Greenway) as a critical facility. Ultimately it will be viewed as a transportation element. Once all of the links are done, we're looking at 30 miles of bikeways and trails throughout the City."

This section of the West Ashley Greenway remains closed to the public as the final touches are put on the bridge and its approaches, expected to be completed by April.