Army Corps of Engineers begins dredging San Jacinto River

One of the first flood mitigation projects to break ground post-Hurricane Harvey, the Army Corps of Engineers began a nearly $70 million project to dredge a portion of the West Fork of the San Jacinto River in September.

Section:
Waterways
Region:

However, according to city and county officials, the project only scratches the surface of the additional efforts needed to reduce flooding risks in the
Lake Houston area.


The Corps’ initial dredging project will merely return a 2-mile stretch of the river near West Lake Houston Parkway to pre-Hurricane Harvey conditions. Dredging is the removal of sediment and debris from the bottom of a body of water, according to the National Oceanic and Atmospheric Administration.
The amount of sediment deposited during Harvey was significant, but the accumulation of sand and sediment in the San Jacinto River and Lake Houston has been an ongoing problem, according to a 2011 report from the Texas Water Development Board. This collection of sediment reduces the amount of water the river and lake can hold, which increases the risk of flooding.


Stephen Costello, city of Houston chief resilience officer, said along with the Corps’ dredging project, the city and Harris County are looking into additional dredging and other solutions that will reduce the amount of sediment being deposited in the river.


“It’s not going to be fixed with one dredging opportunity,” Costello said. “We have to figure out where the material is coming from and how we can control it at the source rather than dredging every couple of years.”


Emergency project
During Harvey, record rainfall and water from Lake Conroe, Spring and Cypress creeks and other tributaries of the of the San Jacinto River caused widespread flooding throughout the area.


The Corps’ project is limited to returning the river to pre-Harvey conditions because it is an emergency project the Federal Emergency Management Agency tasked the Corps with completing as a result of the storm.


Corps officials said FEMA authorized the emergency dredging project because the damage caused by Harvey worsened flood conditions along the river.
In an email, Corps officials said the dredging will not eliminate future flood risks, but it will diminish some of the risks caused by sandbars that were created during Harvey.


“As sediment comes in and [creates sandbars]it slows down the water … and as the rain comes in, it causes the water levels to increase,” Corps Hydraulic Engineer Michael Garske said.


The Corps awarded the $69.81 million project to Great Lakes Dredge and Dock in July. The contractor began dredging the river in September and is slated to complete the project by the end of May.


Alton Meyer, an engineer and project administrative contracting officer with the Corps, said the contractor is using two 27-ton machines known as dredges to remove the sediment by breaking it up with a rotating blade and then pulling it up and out of the river through pumps and pipelines.
Read full article.