Photo taken before crews removed part of the cofferdam (middle) to help rainwater flow downstream
Water from the recent rain continues to recede at the Bois d’Arc Lake dam site with water levels, as of March 24, lower than what remains of the cofferdam.
Approximately 8” of rain fell at the dam site. WFAA reported that DFW Airport saw 11 consecutive days of measurable rain, which is a record for continuous rainfall. It was an extraordinary event which produced extraordinary flooding.
Last week after several days of heavy rains, NTMWD contractors cut a notch in the cofferdam to provide an additional outlet for water to pass beyond the dam. This was done to protect the dam embankment from rising water. Our team notified regulatory agencies of this additional flow. Contractors are evaluating the dam site and will rebuild the cofferdam when appropriate.
A cofferdam is an enclosure built within or across a body of water in order to allow water in the enclosed area to be removed. It is separate from and different than the dam being built for the lake, which is still in place. Contractors completed building the cofferdam earlier this month. It stretches across Bois d’Arc Creek on the south side (or upstream side) of the dam. Following its completion, water from Bois d’Arc Creek was rerouted into the Raw Water Intake Structure, then through the two pipes under the dam, and back into the creek on the north side of the dam. For the past several weeks and prior to cutting the notch in the cofferdam, this was the only way water was getting from one side of the dam to the other.
The cofferdam and rerouting of Bois d’Arc Creek will allow construction crews to build up the embankment in the old creek channel located between the east and west embankments and create one continuous dam embankment.
Flooding along Bois d’Arc Creek occurred for years prior to the construction of the Bois d’Arc Lake dam. In fact, the amount of rainfall that this area receives is one reason why our studies show that this is a great location for a reservoir.
If you have any questions on Bois d’Arc Lake, please email BoisdArcLake@ntmwd.com.