Best Practices for Inspecting, Maintaining, and Repairing DamsAssociation of Construction and Development
February 12, 2013 — 2,389 views
Regular dam inspection is important for several reasons other than to protect its integrity and avoid costly repairs. If not maintained and inspected, dam failure might lead to loss of life, property, water supply, and livelihood. Additionally, severe environmental consequences may follow if dam maintenance and dam repair are not conducted regularly.
General Problems Associated with Dams
There are different reasons as to why a dam may fail, including poor design, improper construction, and lack of proper inspection. While structural failure can result from uncontrolled seepage and uncontrolled flow of water over and around the dam, the structure may itself be weak because of poor construction.
Inspection is essential to carry out the task of dam maintenance and repair as and when required. If a problem is not addressed in a timely manner, it may prove disastrous later on. It is also important to maintain records of all inspections in various formats like notes and photographs. The routine inspections done in efficient manner help in assessing the need for repairs.
Maintaining the Dam
The following measures can be taken to maintain a dam:
- Embankment: While vegetation control is performed twice a year, rodent control, embankment and erosion repair, and erosion protection are undertaken as per the requirement. A healthy stand of grass is needed to prevent erosion and any woody vegetation within 25 feet of dam components has to be removed.
- Spillways: A more or less similar approach as above is followed here for vegetation control, erosion protection, and erosion repair. Additionally, concrete/masonry repair and beaver dam removal are also required. A professional engineer needs to check how much repair work is needed, and remove debris from spillways.
- Intake/outlet structures: Trash rack is a routine maintenance procedure after every storm. Mechanical maintenance is conducted once a year, and internal conduit is checked once a year. Concrete features are examined and maintained once a year. Dam safety personnel or a consultant engineer must be consulted before attempting the repairs.
- Stone and Rubble walls: The maintenance procedure includes inspection of vegetation. Vegetation control is conducted twice a year but missing stones are examined and replaced as required. Trees growing in masonry walls must be cut down and woody vegetation with 25 feet of the structure must be removed. Missing or misaligned capstones in spillways are to be replaced.
- Miscellaneous features: Vehicular and pedestrian access features are inspected and maintained once every year. Fences, locks, and signs of damage are checked annually.
There are basically two types of activities – routine maintenance activities and repair activities – that may or may not require a permit depending on the nature of task involved. The routine maintenance activities like grass mowing, cutting of bush/trees, removal of debris/sediments, restoration of minor eroded areas, minor patching, eradication of rodents, and maintenance of drain valves do not require a construction permit.
While vegetation control is undertaken once a year, other activities are undertaken as required. Most of the other activities including repair and reconstruction of earth embankments, concrete structures, outlet pipes, drainage systems, embankment slopes, control structures, and walls require a construction permit.