Army Corps Finishes Sedimentation Survey Field Work on First Leg of West Fork
Below is the official press release from the U.S. Army Corps of Engineers about the field work for the sedimentation survey they completed on April 9.
“HOUSTON (April 10, 2018)
“The U.S. Army Corps of Engineers, Galveston District began surveying levels of sediment deposits last weekend within the West Fork of the San Jacinto River in response to a State of Texas and FEMA request.”
“To determine the level of shoaling and silt accumulation within the West Fork of the San Jacinto River, a New Orleans District Corps survey crew and vessel began collecting GPS and sonar data near Humble and Atascocita from Apr. 6-9 along a five-mile area between Hwy 69/59 and West Lake Houston Parkway
“Corps Surveyors operated a 20 foot Xpress Boat with survey grade GPS and a sonar transducer to determine sediment deposition,” said Alicia Rea, an emergency management response official with the Galveston District.
“FEMA responded to a request from the State of Texas and under Stafford Disaster Relief and Emergency Act of 1988, FEMA directed the Corps to begin the initial assessment of the conditions. Army Corps Hydrologists will utilize the survey data and use hydrologic modeling to determine the best course of action.
“County and City officials conducted a site visit to the locations on April 10, 2018” said Rea.
“We believe this is the most prudent action to take to better define the scope of work,” said Rea. “The USACE and FEMA are working diligently to expedite the process.” (END OF PRESS RELEASE)
Results of Survey Available Soon
Sources tell me (Bob Rehak) that the results of the Army Corps survey may be available as early as next week. This is good news with hurricane season just six weeks away.
However, there is still a lot of work to do before dredging begins. Everyone must agree on specs for the job. Bidders must be identified. A location to store or dispose of the dredged material must be found. Bidders must have time to prepare their bids. An environmental survey must be conducted. They must allow time for a comment period. The bid must be awarded. Crews must be mobilized.
Some steps can happen in parallel but others must happen sequentially. Sources, who spoke on condition of anonymity, said it could take a month or two before dredging begins – more likely two than one.
We hope that while that work is underway, preliminary work can begin on subsequent legs of the river to further expedite completion of the entire job.
At Least Four Major Blockages on West Fork
Here are four photos from the West Fork that I took shortly after Harvey. They show some of the major blockages between 59 and the lake that we hope the Army Corps addresses. The first two were taken upstream of the West Lake Houston Parkway Bridge. The second two were taken downstream. Approximately 70% of the Kingwood homes that flooded were downstream from the bridge.
The new sandbar deposited by Hurricane Harvey now forces water coming out of the drainage ditch in the background on the left to make a 90 degree left hand turn before it can reach the river. This slows the velocity of runoff and backs up water into subdivisions, like the Barrington in the background. While the sandbar looks gentle from the air it is up to 15 feet high near the ditch.
South of the Kingwood Country Club’s Island Course, Hurricane Harvey deposited several feet of sand that is filling in the back channels and expanding the islands of the West Fork of the San Jacinto River, thus reducing its carrying capacity.
Looking north toward Kingwood’s Kings Harbor subdivision, a popular entertainment district that was destroyed by Hurricane Harvey. The West Lake Houston Parkway bridge is on the left. In the foreground, sand now reaches the tree tops and is virtually as high as the bridge itself. Water used to flow under the bridge and through the area in the foreground during floods. Now it is forced north.
A giant sand dune has formed near where the east and west forks of the San Jacinto join, inhibiting the flow of the river. Engineers say that sediment is not being carried out into Lake Houston (background) as expected. Areas beyond these dunes experienced far less flood damage from Harvey than the areas behind them. That’s the FM1960 Bridge in the background.
By Bob Rehak
Posted April 11, 2018, 225 days since Hurricane Harvey.
