A new stormwater vault at Cardinal Elementary School has been holding up well despite this summer’s heavy rains, county staff say.
The vault under the elementary school’s ballfield in Highland Park-Overlee Knolls, which opened in fall 2023, reached its highest water level yet on June 13 but was never in danger of overflowing.
During that night’s downpour, 0.84 inches of rain fell in just 15 minutes, causing the water level inside the subterranean vault to rise by 45 inches. It was all in a day’s work for the vault with a maximum depth of 12 feet and a 540,000-cubic-foot capacity.
“It is possible that this storm may have caused some flooding in the area if the vault had not been constructed,” county spokesperson Peter Golkin told ARLnow.
It’s been a super-soaked summer, but that’s OK with the huge stormwater vault under Cardinal Elementary ballfields in Westover. Opened in fall 2023, the vault protects much of Arlington with a holding capacity of just over 4 million gallons. https://t.co/rgR2DpplXM pic.twitter.com/j7AxJoFuIm
— Arlington Department of Environmental Services (@ArlingtonDES) July 21, 2025
The vault system, which activated all of 25 times during 2024, has activated 19 times since January this year.
Since its construction, the vault has activated a total of 66 times.
The $18 million vault in the Torreyson Run watershed, which celebrated its ribbon cutting in September 2023, is part of a broader county-wide strategy to mitigate the impacts of flooding following major flash floods in July 2019.
“The stormwater improvements the County has made recently, such as the Cardinal vault, have been performing well and helping to reduce flood risk in Arlington,” Golkin said. “This summer, there was some reported flooding in June in the West Columbia Pike area and this month along the Langston Boulevard and Spout Run area.”
