Inlet Lock #1 - Emergency Repairs - Flood 2010
The National Park Service, Chesapeake and Ohio Canal National Historical Park, will undertake emergency repairs to historic Inlet Lock #1, which was damaged during the flooding of the Potomac River March 12-17, 2010.
Inlet Lock #1 was built by the Chesapeake and Ohio Canal Company, in 1832, to supply water from the Potomac River at Mile 5 of the canal. Water from this inlet lock provided water downstream to Georgetown. The inlet lock was constructed in a similar style to the canal locks. The National Park Service uses inlet lock #1 today for water supply for the canal.
Inlet Lock #1 has wooden gates within a stone masonry channel. The lock gates have sluice gates that are opened and closed as needed to control inflowing water.
During the Flood of March 2010, Inlet Lock #1 sustained severe damage to the downstream set of gates. Due to the damage incurred, the gates may not withstand any future flooding without being replaced.
In order to address the urgent nature of this situation, the NPS will undertake emergency repairs to the inlet lock. The work will include;
-Reopening of an existing 150 foot construction access road. This road access the area located between the Inlet Lock and Lock #5 for equipment needed to remove/replace the lock gates. This roadway will be maintained for long term maintenance for the inlet lock and Lock #5.
-Dewater the lock to remove the damaged lock gates. This will include diversion of river water from entering the lock. It is anticipated that a temporary concrete structure will be used for this activity.
-Removal of the damaged wooden lock gates. Construction of new wooden gates based on the existing gate dimensions. Placement of new gates within the structure.
-Cutting of vegetation currently located on the historic inlet lock and the area between the inlet lock and Lock #5. Park policy recommends that woody vegetation within 20 feet of historic structures be removed to prevent damage. The existing vegetation at the inlet lock will initially trimmed down, but root systems will be retained until structural integrity evaluations can be undertaken. Approximately 15 mature trees will need to be removed to re-open this area. Trees between lock 5 and inlet will be removed for preservation and equipment placement during construction.
-Strengthening of existing masonry cold joints that are deemed to be weak points within the inlet lock. Method of repair will be an epoxy injection grout to fuse the masonry together and seal the cold joint from water infiltration and water pressure internally within the structure.
The above listed tasks will address the emergency repair of the inlet lock. Long term solutions for a more sustainable design will be undertaken in the future.
Previously, compliance was completed to address preservation work to all locks, waste weirs, and bypass flumes within Mile 0-23 of the park. The above listed repairs reflect the approved preservation tasks within PEPC project # 24738, However, due to the urgent nature of the inlet lock's gate project, this package was developed to document the need to address repairs as soon as possible. The existing gates, upon field inspection after flood water receded, yielded that some of the timbers in the existing gates were undersized. The smaller timbers were not in keeping to typical lock gate dimensions found throughout the park at other lock structures. It is uncertain why the undersized timbers were used, but it is felt that they were not as structurally adequate to resist the pressure from the recent flood event.
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. A memo to the file has been issued, based on previous project compliance.
For further information regarding this project, contact Chief of Preservation and Project Management, 1850 Dual Highway, Suite 100, Hagerstown, MD 21740.