Brownell Elevation - 3204 Brownell Ave.
A proposal to construct three new homes atop a historic World War II bunker on Sullivan’s Island has been sent back for revisions following its initial review by the town’s Design Review Board.
The properties, located on Brownell Avenue between Stations 30 and 31, encompass Battery 520, a reinforced concrete coastal gun battery constructed between 1942 and 1944 as part of the Harbor Defenses of Charleston under the Fort Moultrie Military Reservation. Built to defend Charleston Harbor during World War II, the installation was deactivated after the war.
Today, the 38-foot-tall mound that conceals the former munitions bunker spans the center of four long, narrow lots that front Brownell Avenue to the south and I’On Avenue to the north. The former gun mount ends of the bunker have already been converted into subterranean dwelling units. Developer Pat Marr of Cobalt Property Group is now seeking to develop three additional homes across the central portion of the bunker site.
Historic Bunker entrance on I’On Ave left unchanged
The proposal, presented to the Design Review Board on Feb. 18, 2026, would require multiple variances from the town of Sullivan’s Island zoning ordinance, including:
- Increasing the maximum building height from 40 feet to 50 feet, 4 inches.
- Expanding the permitted third-floor square footage from 400 square feet to 1,050 square feet.
- Using substantial portions of the bunker as accessory structure space, exceeding the 750-square-foot limit and requiring recognition of the bunker area as principal building square footage.
- Eliminating the required 5-foot step-back for the second floor, resulting in a second floor that is 28 feet wider than the first.
Project architect Ross Ritchie of Loyal Architects argued that the site presents unique challenges not contemplated by traditional zoning standards.
“There’s nothing in the ordinance about subgrade or partially embedded floors,” Ritchie told the board. “A typical second floor is 20-30 feet in the air. We can’t look at something that’s sitting on grade as something 30 feet in the air.”
Ritchie described what is labeled as a “third floor” under the ordinance as effectively functioning as a second floor, given the sloped topography. He said the design steps back as it rises from the street and attempts to work with, rather than against, the mound.
Southwest Side Exterior Elevation - 3204 Brownell Ave.
“It’s an amazing, incredible site,” he said. “We think it’d be a completely missed opportunity just to plop a house in front of it.”
Conceptual drawings indicate the top level of the proposed homes would offer ocean views despite being located three rows back from the beach.
Former council member Scott Millimet voiced opposition in written comments, stating the homes would dominate the surrounding neighborhood.
“[The houses] will tower over the neighborhood,” he said. “The developer specifically noted the plan is to provide ocean views and enhance the sales price. That should not come at the expense of the aesthetics of the surrounding neighborhood.”
Millimet also raised concerns about stormwater management and potential erosion of the mound if existing ground cover is removed. Marr responded that planned drainage improvements associated with the Station 31 basin project include inlets on Brownell Avenue, and that the development team intends to design an on-site system to capture and disperse stormwater rather than allowing runoff to flow directly into the street.
Ritchie added that while portions of the site are currently classified as pervious, the bunker’s concrete structure beneath the surface limits true soil absorption. He contended that the project remains below the allowable pervious surface coverage and that much of the building footprint would rest atop the existing bunker structure.
The development team stated that the historic wooden facade along I’On Avenue would remain largely unchanged, with only minimal cleanup. The new homes would be sited on the Brownell Avenue side, with the stated goal of preserving the bunker’s concealed appearance as originally intended during its military use.
After discussion, the Design Review Board sent the proposal back for further refinement. Board members encouraged the applicant to more fully acknowledge the historic significance of Battery 520 and to explore design alternatives that do not place new construction directly atop the mound. Board members noted the opportunity to incorporate the bunker’s central opening and interpret its history more directly into the overall concept.
The project could return to the Design Review Board as early as April 15, 2026.