HISTORIC SIGNIFICANCE
The Georgetown Castle, situated at the Georgetown Reservoir, was originally constructed by the U.S. Army Corps of Engineers (USACE) in 1901 as part of the Washington Aqueduct. Operational since 1859, the Aqueduct is a drinking water utility that draws and treats water from the Potomac River for its customers in Washington, D.C. and parts of Northern Virginia.
The Georgetown Castle was individually listed on the National Register of Historic Places (NRHP) in 1975. It symbolizes the beginning of water treatment and USACE’s mission to provide water to the National Capital Region. This unique building was designed to resemble the USACE insignia which was officially adopted by the Corps in 1902. The insignia design was based on the 1839 U.S. Military Academy West Point cadet uniform.
The Castle is associated with the first major expansion of the Washington Aqueduct. In 1882, Congress authorized and directed the extension of the Washington Aqueduct to increase the water supply of the city of Washington. In 1903, USACE initiated construction of the McMillan Filtration Plant, the District of Columbia’s first water treatment facility. The new plant integrated slow sand filtration treatment technology, which significantly improved drinking water quality by filtering out disease-causing contaminants.
ARCHITECTURE AND ALTERATIONS
The 125-year-old Castle is a symmetrical, square single-story brick masonry building with two-story octagonal turrets anchoring each building corner. The turrets and primary building walls support a system of roof trusses. The façade is composed of a three-layer stucco system adhered to the outermost wythe of brick which is scored to resemble stonework. Historic bricks are soft and porous compared to modern masonry. The stucco and historic brick materials work together as a permeable, flexible system which allows moisture to migrate outward and allows the masonry structure to expand and contract due to thermal movements.
In the spring of 2016, 115 years after its original construction, USACE began work to rehabilitate the Georgetown Castle as part of the Georgetown Reservoir Building Improvements Project. The goal of this ongoing, complex undertaking is to complete interior and exterior repairs of multiple buildings at the Georgetown Reservoir site to sustain their long-term preservation and continued operational use as part of the Washington Aqueduct system.
“As part of the restoration and reconstruction, the team consulted and worked in close partnership with the DC State Historic Preservation Office, National Park Service, Advisory Council on Historic Preservation and others in order to identify appropriate mitigation and successfully comply with the National Historic Preservation Act,” said Baltimore District Planning Division Chief, Amy Guise. “This partnership will ensure the Georgetown Castle retains its structural and historical integrity.”
The preservation effort initially focused on the building facade – the layers of stucco that cover the underlying masonry structure. To confirm the structural integrity of the building, USACE performed a condition assessment of the Castle after the stucco was removed. This assessment identified structural and safety concerns due to severely damaged masonry caused by excessive water infiltration over time.
The structural integrity of the Castle relies on the condition of the masonry walls and turrets, and the interlocking continuity of the masonry throughout the structure.
To address the structural concerns, all four turrets were reconstructed to reinforce the Castle’s overall structural stability and to match their exact original appearance, including the scored stucco exterior. The brick masonry was reinstalled so that toothed edges interlock at the structure’s joints, a feature that is designed to prevent the structure from moving, ultimately making it more resilient. During this work, all original bricks that retained structural integrity were salvaged and integrated into reconstruction to retain as much of the historic fabric as possible. Non-viable bricks were removed and replaced in-kind with bricks matching the characteristics and color of the original materials. This reconstruction, combined with regular maintenance, will prolong the life of the symbolic Georgetown Castle for decades to come.