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Four stone lions stand guard on Lions Bridge at the Mariners’ Museum and Park. Underneath is a dam in need of some improvements.
Lions Bridge Dam, which separates Mariners’ Lake from the James River, was built in the 1930s — a time before Virginia had dam safety regulations. It’s supposed to prevent flooding, but it’s been overtopped twice since 2012, which has caused minor damage to the area.
“The dam was constructed before there was as robust of a regulatory environment as there is today,” said Howard Hoege III, Mariners’ Museum president. “The truth is ever since that dam construction occurred, up until about two years ago, this dam has lived entirely outside of the regulatory framework.”
If the work isn’t done, the state’s Department of Conservation and Recreation could come and shut the area down. The department granted a conditional certificate to operate the dam nearly two years ago with the stipulation that the city had to make progress toward bringing the dam into compliance.
The strategy, Hoege says, is to allow the lake to overtop the dam in the event of major flooding and ensure the dam is protected “if and when it’s overtopped.”
The museum owns the dam and lake, but they’re part of the city’s stormwater system, so, the city is footing the estimated $11 million bill with money collected from its stormwater fees.
The project will require removing many of the trees on top of the dam because safety regulations do not allow for woody vegetation. The regulation is in place because if the tree or any other plant with deep roots were to die, it would rot from underneath and could cause erosion that could lead to the failure of the dam.
It’s possible that grasses could be planted in the area where the trees have to be removed, but that part of the project will not be discussed until later.
There’s one tree that might be saved. The dam’s planning team, which includes the museum, the city and engineering firm Arcadis, has requested an exemption to the no-trees rule for an old live oak tree on the northwest side of the dam.
The museum’s park department, which includes a certified arborist, has proposed a monitoring and maintenance program for the tree so that “if and when it becomes a safety problem for the integrity of the dam” it can be addressed, Hoege said.
The request was submitted with the design at the end of March, and it may take another month or two to hear whether it’s accepted and the tree is allowed to stay.
“There are really two main benefits to doing this project,” Hoege said. “The first is that we’ll have a stable dam ... Number two is, this actually opens up a viewshed.”
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There’s a lot of foot traffic along the water, Hoege said, but there’s not supposed to be. The people who walk down along the water are contributing to erosion. The hope is that with the trees removed, it will take away some of the temptation because of a better view of the water.
Other elements of the project include plans to line the toe of the dam with riprap — a rocky material to prevent erosion and to replace the existing asphalt at both ends of Lions Bridge with concrete.
The asphalt is weak against rushing water, which could lead to damage to the dam, Hoege said. The plan is to then cover the concrete with asphalt.
The planning team does not anticipate any long-term road closures on Museum Drive during construction. Individuals will be used to direct traffic as needed.
The park’s goal is to keep the Noland Trail open throughout the process, but parking will not be available at the bridge.
Plans for improvements to the dam began back in 2013. Construction is expected to begin in February or March and will take about a year.
Jessica Nolte, 757-912-1675, jnolte@dailypress.com