Antietam Aqueduct Structural Investigation
The National Park Service will undertake structural investigations on the Antietam Aqueduct, located at Mile 69.36 of the Chesapeake and Ohio Canal National Historical Park. The aqueduct was built to convey the canal across Antietam Creek in Washington County, Maryland. The stone masonry aqueduct, circa 1834, is 140 feet long and has three elliptical arches. The prism retaining walls were partially destroyed during the Civil War. The damage was repaired in-kind by the Chesapeake and Ohio Canal Company. This aqueduct is one of eleven such structures built by the canal company which was in operation until through 1924.
During the years following the cessation of canal operations, the aqueduct was minimally maintained, and deterioration from aging and natural events, such as flooding, began to take its toll. In the mid 1960's the prism walls were stabilized in an effort to preserve and maintain this structure. Since the 1960's, the National Park Service has undertaken preservation campaigns to keep the structure in a stable condition. However, in spite of the preservation work, the south prism wall has been continually moving over the last several years. Most recently the walls were selectively repointed to mitigate water infiltration until a full scale stabilization project could be implemented.
The aqueduct is an integral part of the park and visitors use it on a daily basis. Additionally, the dry canal prism of the structure allows emergency, law enforcement, and maintenance vehicles to access the park as needed.
A structural investigation is required to determine causes of the continual movement and to determine if aqueduct is capable of carrying vehicular loads.
The scope of work will include the temporary removal of wall stones to examine inner wall conditions, the installation of crack monitors, photographic documentation, underwater investigations of the piers and abutments, and structural measurements.
The park's Interdisciplinary Team reviewed the project for impacts to natural and cultural resources. The project does not pose any serious or long-term effects to the environmental, historical, cultural, archeological, or visual resources. It meets categorical exclusion #C.4 – Routine maintenance and repairs to cultural resources sites, structures, utilities, and grounds if the action falls under an approved Historic Structures Preservation Guide or Cyclic Maintenance Guide, or if the action would not adversely affect the cultural resource.
The project also meets the National Historic Preservation Act/Section 106 Programmatic Agreement, Exclusion #IV.B 9 – Rehabilitation work limited to actions for retaining and preserving, protecting and maintaining, and repairing and replacing in kind materials and features, consistent with the Secretary of Interior's Standards for Rehabilitation and the accompanying guidelines.
For further information about this project, please contact Exhibit Specialist, at 1850 Dual Highway, Suite 100, Hagerstown, MD 21740.