CONNstruction - Winter 2015 - (Page 7)
The Big Dam Challenge
By Don Shubert
Once every four years, the American Society of Civil
Engineers releases an assessment of the condition of
the nation's infrastructure in a report card. Categories
within this report include several water-related areas,
such as ports, wastewater, levees, drinking water, inland
waterways, and dams. Two areas that could use more
attention are dams and levees. Since 1998, the grades
have been near failing, due to delayed maintenance and
The condition of Connecticut
dams mirrors the national trend.
Out of the 4,646 dams in inventory,
about 277 are classified as
significant-hazard dams and 267
are high-hazard dams.
Dams earned a grade of D. The average age of the
84,000 dams in the country is 52 years old. The nation's
dams are aging and the number of high-hazard dams is
on the rise. The hazard classification of a dam is determined by considering: the height of the dam; the size
of the pond; the location of structures below the dam;
and the expected mode of failure for the dam. Based on
these factors, the likelihood that human life or property
damage would occur during the hypothetical breach of
a dam determines the classification.
The challenge with dams is two-fold. The first challenge is facing years of age and deterioration. The second
challenge is presented by commercial and residential
development below the dams. Many dams were built
as low-hazard dams protecting undeveloped agricultural land. However, growing populations and greater
development below dams have been increasing the
potential risks associated with a failure. This aspect of
the challenge has pushed the overall number of highhazard dams to nearly 14,000 in 2012.
Nationally, the number of deficient dams is currently more than 4,000, which includes 2,000 highhazard dams. The Association of State Dam Safety
Officials estimates that it will require an investment of
$21 billion to repair the aging, high-hazard dams. The
condition of Connecticut dams mirrors the national
trend. Out of the 4,646 dams in inventory, about 277
are classified as significant-hazard dams and 267 are
Levees fared worse than the dams, earning a grade of
D-. The nation's estimated 100,000 miles of levees can
be found in all 50 states and the District of Columbia.
Many of these levees were originally used to protect
farmland, but their uses have been expanded and are
now increasingly protecting developed communities. The
reliability of these levees is unknown in many cases, and
the country has yet to establish a National Levee Safety
Program. The cost to repair or rehabilitate these levees
is roughly estimated to be $100 billion by the National
Committee on Levee Safety.
Connecticut currently has 14 sites on the national priorities list, and approximately 29 miles of levees according to the current FEMA Midterm Levee Inventory. An
example that stands out for levees in need of attention
in Connecticut is the flood protection system along the
banks of the Connecticut River in East Hartford and
Hartford. This system is the largest of its kind in New
England and represents one of the largest flood control
systems on the East Coast.
As with many levees around the country, substantial
development has occurred behind this levee over the
years, increasing the risk associated with a substantive
failure. In Hartford, for example, approximately 20 percent
of its land area is in the levee protected zone, most of
which is comprised of prime commercial, institutional,
and residential properties. Other infrastructure that would
be impacted includes the Interstate Route 84/91 interchange, the Metropolitan District regional sewage treatment facility, Brainard Regional Airport, and an aviation
fuel supply line serving Bradley Airport and Westover
Air Force Base.
While it is clear that we have a significant backlog
of overdue maintenance across all infrastructure systems, the dam and levee challenges should not be
overlooked. The risks of failures continue to compound
connstruction / WINTER 2015 / 7
Table of Contents for the Digital Edition of CONNstruction - Winter 2015
The Big Dam Challenge
MDC’s Office of Diversity: Promoting
Call Before You Dig – System Enhancement!
Cleaning Water, Creating Jobs
Connecticut’s New Port Authority Key to Economic Growth
40-Year Old Treatment Plant Gets Royal Flush Upgrade
What You Need to Know About WOTUS
AGC of Connecticut Industry Recognition Awards
Connecticut Environmental & Utilities Contractors Association Annual Fall Meeting
Diggers Mixers Fixers – 2015 Golf Outing!
CCPC – 2015 Summer Outing!
2015 Young Contractors Forum bus trip to the new Yankee Stadium
2015 YCF Fall Membership Meeting
Index to Advertisers/Advertiser.com Published
CONNstruction - Winter 2015