Underground stormwater system doubles as parking lot for Virginia equipment dealer
When Warrenton Equipment reopened a Fauquier County tractor dealership after a seven-year closure, the company needed a stormwater management system that wouldn't eat into its limited parking for tractors, mowers and other equiopment. Owner Richard Varona used buried arch-shaped stormwater collection chambers to construct an underground detention system instead of an open basin to retain stormwater.
"The county wanted a stormwater management system," Varona said, "and originally insisted on one that was open. They said they've heard of the underground systems before, but I'm not sure if they've actually installed them. But after a lot of going back and forth — it took two years to get approval from the county — we finally got them to accept the underground one. We didn't want to lose any land that we could use.
"The county wanted a stormwater management system," Varona said, "and originally insisted on one that was open. They said they've heard of the underground systems before, but I'm not sure if they've actually installed them. But after a lot of going back and forth, it took two years to get approval from the county, and we finally got them to accept the underground one. We didn't want to lose any land that we could use.
"We started our company in 2000, but the business has been here since the 1950s as a tractor dealership. It went out of business in 2013 and for about seven years it was closed. We opened it back up with the same types of tractors. It's a Massey Ferguson dealership, and it's one of the iconic properties in the county because it's been here so long."
"But since it closed, there was a requirement to put in a stormwater management system," Varona said. "For 60-plus years, they didn't have one, just an open pond. That didn't get grandfathered in, so we had to adopt the new environmental rules, which included putting in a stormwater management system with bioretention. We were restricted, however, by the low degree of slope angle for the water to flow to the nearby stream. It was almost flat. We had to find a system that would have a low profile and would work."
A prime agricultural area in northern Virginia with more than 1,000 farms, Fauquier County is also home to the Fauquier Education Farm, which trains future farmers and grows produce shared with local food banks.
According to the updated Fauquier County ordinance and the Virginia Erosion and Stormwater Management Act of 2024, an erosion and stormwater management system is required for most land of more than 10,000 square feet that will be converted from pervious to impervious surface.
"In our county, it's more of an agricultural area really, it's very hard to have any type of commercial properties," Varona said. "We have only two and a half acres here."
That limited space for large tractors, other equipment, offices and garages made every square foot of open area critically important to current operations and future growth of Warrenton Equipment.
Local civil engineering firm Carson Land Consultants LLC, Warrenton, Va., drew up the final plans for the stormwater management system, which were reviewed and approved by the county.
The underground system at Warrenton Equipment consists of 56 StormKeeper SK75 Chambers from Lane Enterprises Inc., Camp Hill, Pa., for a total capacity of 5,660 cubic feet of water. Integrated into the system are units that provide treatment of the first flush and control the outflow rate of stormwater to reduce erosion. The chambers stand 30 inches tall.
The arched chambers were selected because they accommodate a low-profile design with minimum top cover and are strong enough to handle the weight of heavy equipment. Rated to handle AASHTO structural design requirements, they are injection-molded using polypropylene for extra strength. The company manufactures three additional chamber sizes — 16, 45 and 45 inches high. A built-in water quality row, the Lane StormKeeper Sediment Strip, allows for sediment removal and maintenance access within the system. This treatment row was used to meet stormwater management requirements for total suspended solids.
Varona acted as his own general contractor with a crew of four to excavate the 65-foot-long by 40-foot-wide by 7-foot-deep area. A 1-foot layer of crushed stone served as the bed. Non-woven geotextile enveloped the chambers to prevent native soils from migrating into the stone voids. Backfill was 6 inches of crushed stone followed by 2 to 2½ feet of native soil from the excavation.
The downstream end of the system has an outlet structure with a weir plate that reduces the flow rate of water leaving the site. Dual-wall, corrugated high-density polyethylene pipe from Lane was used to convey water from the chamber system outlet to a nearby stream.
According to Varona, installation took about a week with a crew of four. "The county was surprised it was done that quick. They said, 'Oh, it's going to take you three months, four months.' I told them it doesn't seem like it's that difficult. We had it down to grade and we had to take out four feet, and then basically, it was filling it in with dirt and gravel, like the drawing showed.
"We purposely went to Lane because they are here in our area and helped with calculations and the site plan. They also stayed with us during the couple of years it took for the county to approve the project. Plus, their local engineer and salesman educated us on how to install the chambers and were on-site when we did it.
"We had some heavy rains and haven't had any stormwater problems at all. The system works well, helps us to protect the environment plus we gained a much-needed, large parking area," Varona said.