|The masonry sluice from the modern|
culvert under Clara Barton Parkway.
(Rod Mackler photo)
Historic Culvert No. 2
By Rod Mackler & Ned Preston
Walking upriver from Lock 6, towpath users soon reach a path leading down to the mouth of the former feeder canal that’s now used as a kayak course. This popular spot is just below the modern Little Falls Intake and Pumping Station. Surprisingly, there’s no marker to indicate that this area was the site of the groundbreaking ceremony on July 4, 1828, when President John Quincy Adams inaugurated construction of the C&O Canal.
A little farther upstream is another interesting feature that’s easy to miss: Culvert No. 2. One of several culverts built under a contract awarded in 1828, the structure was designed to carry a stream under the canal and into the Potomac River. Today, a mass of sediment almost blocking the canal at mile 5.74 is a clue to the location of the culvert. Sadly, this obstruction also shows that the structure has long been unable to handle the silt-bearing runoff generated by heavy rains.
By scrambling through trees and brush to the river’s edge, a visitor can see the culvert’s outfall, where a modest flow still exits through a stone arch that is now submerged beneath the water line. To view the culvert’s entrance on the berm side of the canal is more difficult, requiring the assent of the U.S. Army Corps of Engineers, the Pumping Station’s operator. With this permission in hand, environmental committee chair Rod Mackler visited the site on January 16, accompanied by Ned Preston and civil engineer Matt McCarty. They found that the arch on this side of the canal is buried, and that only a small quantity of water enters the culvert through an inadequate and partially blocked concrete drain.
Matt, a member of the American Society of Civil Engineers, kindly volunteered to document the situation with photos and measurements, and later asked a colleague for a list of steps needed to correct the problem. Besides coordination with multiple government agencies, these actions would include technical investigations such as a survey of the area and a preliminary probe with a length of rebar. Drawings would define the project as part of documentation needed for the necessary permits. On the river side, the outfall run would be cleared. The culvert’s interior channel would be freed from debris using high-pressure water jetting or other techniques, and damming would possibly be needed to prevent water from entering during this process. After inspection to determine the extent of structural damage, repairs would proceed, debris and sediment would be removed, and the areas at both ends of the culvert would be stabilized. A very preliminary estimate places the cost of the project in the neighborhood of $1 million.
A key aspect of the project is the source of the runoff. Water reaches Culvert No. 2 along a masonry sluice from a modern culvert under Clara Barton Parkway. That culvert in turn is fed by one that passes under MacArthur Boulevard, drawing water from a ravine on the eastern side of Wapakoneta Road. On high ground above the ravine is a large federal office complex, accessed from Sangamore Road, which earlier housed the Defense Mapping Agency and National Geospatial-Intelligence Agency. Local residents have reported an increase in runoff since the establishment of that facility, which included extensive paving. The complex is currently being repurposed and greatly expanded to become the Intelligence Community Campus–Bethesda (ICC-B), which will include important elements of the Defense Intelligence Agency and the office of the Director of National Intelligence.
The ICC-B developers have indicated that their plans to make it a “green” installation include remediation of earlier environmental harms. On behalf of C&OCA, president Barbara Sheridan in early February sent a letter to the director of the zoning office of Montgomery County, Maryland, pointing out that the damage to the C&O Canal from runoff is an obvious case of such harm. Noting that the cost of renovating Culvert No. 2 is beyond the National Park Service’s resources, she requested that the repairs be included in the ICC-B project budget of at least $300 million. Copies of the letter were sent to the chair of the Montgomery County Planning Board, Maryland’s two U.S. senators, the congressman in whose district the site is located, and the Director of National Intelligence. Also receiving copies were the superintendents of the C&O Canal National Historical Park and of the Clara Barton Parkway, which has been designated as the lead NPS unit for coordination with the ICC-B project. We hope that this appeal will result in restoration of the ability of historic Culvert No. 2 to fulfill its important role in maintaining the canal.
|Matt McCarty inspects the Culvert No. 2 towpath arch. (Rod Mackler photo)|
|The partial blockage of the canal prism above Culvert No. 2. (Matt McCarty photo)|