by Richard C. Wakeman, P.E., Vice President Civil Engineering

     Kathryn C. Serra, P.E., Assistant Project Engineer

Dams in New York State are regulated by the New York State Department of Environmental Conservation’s Bureau of Flood Protection and Dam Safety.  There are over 5,000 regulated dams in New York State, which are given hazard classifications based upon the potential for damage occurring downstream if the dam were to fail.  High hazard dams are dams that will cause a loss of life in the event of failure, while failure of intermediate hazard dams will likely not cause a loss of life, but will cause substantial damage and economic loss.  There are 383 high hazard dams in NYS, of which over 50% of the dams are owned by local governments.  Of the 756 intermediate hazard dams in NYS, 25% are owned by a local government.  The remainder of the dams in NYS are low hazard, which means little to no downstream damage will occur in the event of failure.

Does your Town own a dam? The majority of dams owned by a local government are for public water supply, recreation or flood control.  Even if your Town is not a dam owner, there may be a high or intermediate hazard dam in your Town or upstream of your Town. 

The threat of sudden flood events associated with dam failures is growing in NYS, as a majority of dams in the state were built over 60 years ago and are in need of major repairs and upgrades.  The integrity of many dams has been declining due to lack of maintenance and upkeep; and additionally external factors such as development within the watershed and climate change place more stress on dams.  An increased population has placed more infrastructure, homes and businesses downstream of dams, which will be severely impacted in the event of a dam failure.  Most of those people do not even know there is a dam located upstream of them!  Failure of even a small dam could be a catastrophic event to a community.  For example Hadlock Pond Dam in the Town of Fort Ann, Washington County, failed after reconstruction on July 2, 2005 and caused severe downstream flooding; destroying roads, homes and property.  Luckily, no one was killed by this incident.  There have been many other dam failures in the past 5 years across the country, including dam failures in Wisconsin, Mississippi, Missouri, California and Hawaii.  The Koloko Reservoir Dam failure in Hawaii (2006) killed 7 people.  So far in 2009 a dam at a coal-ash plant failed in Tennessee causing environmental destruction, and a dam in Indonesia failed and killed hundreds. 

In 2009, the NYSDEC will likely pass amended Dam Safety legislation that will require all owners of intermediate and high hazard dams to produce Emergency Action Plans for their dams.  Current regulations only mandate these plans for high hazard dams.  The proposed regulations will require that EAP’s be developed within 12 months of the passing of the regulations.  The draft regulations can be viewed at: http://www.dec.ny.gov/regulations/41934.html

An Emergency Action Plan in the Event of Dam Failure includes two distinct, but related components:

1.  Dam Break Analysis and Inundation Mapping.  These analyses are performed by engineers and include advanced hydrologic and hydraulic modeling.  The inundation maps provide information for the areas impacted under dam failure scenarios, and provide emergency responders information on flood wave travel time, the depth of water and the location of access routes to the affected area.  It is recommended that inundation maps be prepared in a Geographic Information System (GIS) format.  The use of GIS technology allows for easy identification of properties within the inundation zone via use of a tax map database.   A list of affected property owners can be easily prepared and updated.  In Counties with a Reverse 911 system, the system can be linked to the GIS file and notification quickly sent out to those within the inundation zone during an emergency scenario. 

2.  Emergency Response Information.  Information is provided for emergency responders in the EAP, including notification flow charts and emergency response protocol.  It is important for the EAP developer to include emergency responders during the development of the EAP, since these responders will be those using the plan in an emergency.  Many emergency responders already have other plans for a response to an emergency within their jurisdiction and have ideas or established protocol that can be included in your EAP.  In addition to providing information geared towards emergency responders, the EAP should include basic information about the dam, and how a lay person can identify potential situations at the dam.  Remember, it is not always the dam’s owner or engineer that notifies local emergency responders if there is a situation at the dam.  What if a jogger who runs by the dam every morning notices muddy water coming from the embankment and calls Town Hall? What if the jogger calls 911?  The plan should be basic enough such that this potential emergency can be quickly conveyed to the appropriate authorities.

The EAP should not be a document that just sits on a shelf.  Once the plan has been created, it is recommended that it be tested regularly through use of table-top exercises or other drills.  The EAP should be reviewed on an annual basis, since people move in an out of the inundation area, and emergency responders change.  Good planning can go a long way into possibly preventing a disaster or properly responding in the unfortunate event that one does occur.

Kathryn Serra, P.E. is an Assistant Project Engineer at C.T. Male Associates, P.C. located in Latham, NY.  Recently, she attended the New York State Association of Towns Annual Meeting in New York City where she gave a presentation on Emergency Action Plans and what it means to your Municipality.  If you would like more information on Emergency Action Plans Kathryn can be reached at (518) 786-7400.