On any given day, ships carrying cargo from Mexico to China pull into one of the 28 ports along the Texas coast to deliver imported goods ranging from coffee to cars – a maritime industry that generates $135 billion in economic value to the state and creates nearly one million jobs.
With Texas ports ranking first in the nation in waterborne commerce and handling nearly 17 percent of all of the nation’s port tonnage, it’s imperative the waterways stay open for navigation. No easy task for the U.S. Army Corps of Engineers Galveston District, the federal agency entrusted with maintaining 1,000 miles of channels along the Gulf of Mexico.
“Dredging is essentially the underwater excavation of a channel,” said Chris Frabotta, chief of the USACE Galveston District’s Navigation Branch. “Throughout the year, sediments within the water column will settle and accumulate within the channel, a process that is known as shoaling. If the shoaled material is not removed then the shipping channel will eventually become restricted or even unusable.”
The USACE Galveston District monitors and maintains the federally-authorized navigation channels along the coast of Texas, removing approximately 30-40 million cubic yards of shoaled sediment at a cost of approximately $100 million per year. Currently, the Galveston District is executing 13 maintenance dredging contracts between Port Arthur and Corpus Christi, including work in the Galveston area.
“The Galveston Entrance Channel is typically dredged every 18 months,” said Project Engineer Brandon Smolinsky, USACE Galveston District. “The Galveston Harbor is unique because there is quite a bit of current ripping through from the bayside. As result, the harbor shoals up quickly. Additionally, the number of storms that hit the area can increase the amount of material deposited into the harbor.”
Another determining factor regarding how often USACE Galveston dredges a channel concerns how deep it was previously dredged. In the case of the Galveston Harbor, the Corps favors maintaining the 45-foot authorized channel at a depth of 48 feet, to include three feet of advanced maintenance.
“We prefer to maintain the channel to the advanced depth so we don’t have to dredge as often,” said Smolinsky. “If we maintain the channel at just 45 feet, it could potentially have to be dredged every six months.”
Failure to conduct advanced maintenance often results in reduced efficiency, light loading of vessels and more frequent dredging at a higher overall cost for re-dredging.
While the Houston/Galveston Entrance Channel is authorized to a depth of 45-feet, the Galveston District dredges this channel to a depth of 49-feet in order to provide a 45-foot channel between dredging projects.
According Frabotta, each foot of depth lost by not dredging to an authorized depth has an annual economic impact of between $48 million to $180 million per foot, dependent upon cargo value and size of the ship.
With so much at stake, the USACE Galveston District does not take its role as the “Custodians of the Coast” lightly.
“The Galveston District is responsible for maintaining federal navigation channels for four of the top 10 ranked ports in the United States [with respect to tonnage]” said Frabotta. “We understand the national, regional and local significance that waterborne commerce has on the nation and the State of Texas and we work diligently to ensure safe and reliable channel availability.
Established in 1880 as the first engineer district in Texas to oversee river and harbor improvements, the USACE Galveston District continues its mission of building strong along the Texas coast.
Dredging Today Staff, February 19, 2012; Images: usace