Is the Beltway to Blame?

Is the Beltway to Blame?

’82 study suggests Beltway restricted creek’s flow, county’s precautions.

In April, 1982, the engineering firm Camp, Dresser and McKee presented a report to the County of Fairfax Department of Public Works. An inter-office memorandum between two directors within the Department of Public Works describes the report (which is more than 100 pages long) as an analysis of the flooding problems of “167 dwelling units … located within the 100 year flood plain limits of Cameron Run.”

“The basic cause of the flooding problem in this community is attributed to the insufficient channel capacity in Cameron Run,” the memo reads.

But the most striking aspect of the memo is not its explanations, but its lone, prominent recommendation.

“The recommended engineering solution involves the construction of a six-foot high concrete floodwall around the lower portion of the Huntington Community at an initial estimated cost of $3,537,000 … Funds are not available to implement this project but could be considered in a future storm bond referendum.”

24 YEARS into the future, there is no referendum, and as residents of Arlington Terrace and Fenwick Drive are well aware, there is no floodwall.

Mount Vernon District Supervisor Gerry Hyland first learned about the study several weeks ago, after Public Works employees stumbled upon it while responding to the flood.

“I was shocked. I was outraged really,” Hyland said. “We recommended it years ago. Why didn’t we do it? Apparently it was money … it languished there for 24 years.”

But a thorough reading of the report raises questions about whether the floodwall would have protected residents. A bill of $3.5 million may have dissuaded county officials from acting on the recommendation, but the efficacy of the wall was undermined by a mandate that if a grotesquely swollen Cameron Run had to be forced south into the homes of Huntington or north onto the Beltway, it must be the people that received the water’s destructive force, not the road.

THE THIRD SENTENCE of the report describes the scope of the run-off that flows into Cameron Run. “The land area that drains into Cameron Run and its tributaries is the third largest watershed in the county, covering an area of about 42 square miles. It is also one of the most heavily populated.” The engineers calculate that a one hundred year flood would rise 14.34 feet. This would be high enough to flood 167 homes as well as sections of the Beltway.

The impermeable surfaces that accompany high population densities across a massive floodplain increased the amount of water that runs into the stream. Heavy silting also restricted the amount of water Cameron Run could contain. The report concludes that human intervention also constricted where the water could flow. It identifies a retaining wall adjacent to the Grosvenor Riverside Apartments as the “primary” source of constriction in the stream. It also fingers the George Washington Memorial Parkway Bridge, though “to a much lesser extent.”

Removing these constrictions was deemed possible but not “realistically practical.” However removing another source of constriction was even less realistic. “The Beltway has a pronounced detrimental effect on flooding within the study area,” the report says, because it blocks rising water from spreading across the stream’s northern bank. “It constricts the flow section and exacerbates the community flooding problem.”

The study reveals that the beltway not only aggravates flooding, it restricts the scope of protection for Huntington residents. “We have approached this study with the precondition that the beltway flooding should not be aggravated by any flood control measure which protects the community. This premise impacts the effectiveness of the measures we have selected.”

The study shows that a floodwall would have to be 7.8 feet high to achieve the 14.8 foot elevation “necessary to protect the community." The six foot floodwall that is ultimately recommended in the Department of Works memo would only block water that rose 13.5 feet. Anything higher, for instance than the 14.34 feet of a 100 year flood, would flow right over. But a higher wall would push water onto the beltway, an unacceptable result. The height of 13.5 feet was apparently chosen purely because it would not cause flooding on the beltway. “We place its top at 13.5 feet to allow freeboard for beltway flooding,” the report reads.

BECAUSE PROTECTING THE BELTWAY was prioritized over protecting the 167 homes in Huntington, the higher floodwall was eliminated as an option. In its place, the report proposed four combinations with the potential to protect Hungtington from a 100 year flood:

Building a levee and dredging silt from Cameron Run;

Building a levee and “channelization” (a combination of dredging and bank reinforcement);

Building a floodwall and dredging or channelization; or

Enlarging the Parkway Bridge and channelization (this was deemed impractical because of the historic value of the bridge).

All four solutions would be more expensive and significantly more difficult to implement than a higher floodwall. The cheapest of these, building a levee and dredging a 200-foot swath of Cameron Run, would cost $3,733,000. The annual maintenance costs, including dredging, would be $642,000. The higher 7.8 foot high floodwall that threatened the Beltway would cost slightly less than this, $3,537,000. Its annual maintenance would have been significantly less, $385,000.

One of the final paragraphs of the report recommends “further coordination with [Virginia Department of Transportation] concerning the beltway. [The higher floodwall] is one of the most cost-effective options and will protect the Arlington Terrace Community from a 100 year event.”

Of the shorter floodwall with no levee, which is the solution ultimately recommended by the Department of Works memo, the report reads, “we expect that overtopping would occur at about a 75 to 80 year flood. The question to be resolved then becomes one of whether an additional 20 to 25 year level of protection would be worth the annual difference in cost … it would be mandatory that channel sedimentation does not occur … a biannual maintenance dredging program would probably be in order.”

The Department of Public Works memorandum mentions no such dredging. It quotes the $3,537,000 cost of the 7.8 foot floodwall to build a 6 foot floodwall (which the report says would cost $3,109,00 without a levee). The sender of the memorandum, Joseph Sunday, Director of the Utilities Planning and Design Division, suggests it would require only $25,000 in yearly maintenance.

AFTER BEING TOLD of the report, Arlington Terrace resident Geoff Livingston expressed his appreciation for the county. “The county could have just as easily tried not to reference these reports. Its pretty clear that they are bent on doing the right thing ... it doesn’t have to be ugly.” Livingston said he has retained a lawyer in expectation of a class-action lawsuit. Finding a plaintiff will hinge upon the results of ongoing flood studies.

“In general I would say the neighborhood feels that this validates our feelings that this was not a natural event and we’re glad to see both the county and the state proceeding with their investigation and proceeding in a way that’s open,” he said. “We think they’re doing the right thing and we hope they continue to do the right thing, including compensation as responsibility dictates.”