Photo By James Finn | The Dredge Goetz performing channel maintenance within Pool 20 of the Mississippi...... read more read more
Almost 1.4 million cubic yards, or 70,000 semitrailer loads – that’s the amount of material the Dredge Goetz has removed from the navigation channel in the Rock Island District over the last five years. This figure represents only a fraction of the total amount that has been dredged by the Goetz throughout the St. Paul, Rock Island and St. Louis Districts combined since 2013.
The Goetz, based out of the St. Paul District, spent much of August and September in the Rock Island District, working in Pools 12 and 20. For those who don’t know exactly how this hydraulic dredge works, or the purpose of dredging the navigation channel, Adrian Loewenhagen, Assistant Captain of the Dredge Goetz, has a simple explanation, “It’s like a blender attached to a vacuum cleaner hose,” he said. “It stirs up the bottom and sucks it up and discharges it to wherever the authorized site is.”
As for why dredging the channel is needed, that comes down to the navigation mission and the challenges put in place by a water source as powerful as the Mississippi River. In order to maintain a 9-foot navigation channel, material that settles in the main channel must be removed. This material, such as sand, soil and decomposing vegetation, is constantly moving around in the river and often settles into the channel as the current moves it downstream. During dredging, the material is removed from the channel and is set aside for a variety of uses including habitat development, wetland creation, aquatic habitat enhancement, winter road maintenance, levee repair and improvement, aggregate for concrete, bank protection and general purpose fill.
While channel maintenance and dredging work typically takes place during low-water times, the rollercoaster of river levels experienced on the Mississippi River this year has made dredging quite challenging. Loewenhagen said currents from high water present the greatest challenge.
“When you are dredging in the high water, the current is so strong that it’s pretty much filling back in what you already dug out,” Loewenhagen said. “You will take a bunch of sand out and that sand will fill right back in because of the current.”
During low-water times, the battle becomes keeping up with the mission.
“If it’s a really bad year, it’s hard just to keep up because you might have half a pool that is too shallow for navigation so you are constantly just go, go, go,” said Loewenhagen. ”You might just be making paths that are deep enough to get through for now, so you can get everything cleaned up and get traffic flowing.”
While the big dredge vessel is what most people might associate with the dredging process, there is a lot of work that goes into channel maintenance before the heavy equipment arrives. Thomas Burrow is a Survey Technician out of the St. Paul District and says even though the crew out of St. Paul is the group that performs the dredge work, the survey crew from the Rock Island District plays a distinct role in the predredging process.
“The Rock Island survey crew does the pre-survey work, so they will survey the conditions and find the bad spots and calculate the volumes [that need to be removed] from that,” said Burrow.
Burrow continued by explaining that once the initial survey is complete, the Rock Island survey team builds matrices which include layered information about channel depths and material volume. These matrices are then used to calculate the amount of material the dredge needs to remove and helps the pilot of the dredge determine how deep the cutter head must go.
Dredging is a 24/7 operation, the crews performing the operation don’t get to clock out and go home every night. During their work in Pool 20 near Keokuk, Iowa, the crew of the Dredge Goetz worked seven days straight before having seven days off. As the Dredge Goetz does not have dinning or sleeping quarters onboard, another vessel, the Quarters Boat Taggatz, follows the Goetz wherever it is working to allow space for the crew to eat, sleep and enjoy some downtime when not on shift. When asked about living out on the river for a week at a time, Loewenhagen had nothing but good things to say.
“I love being out here. You’re on the river, doing something you enjoy, not stuck in a factory. You’re always meeting new people which is always fun.”
Burrow echoed his sentiments saying, “It always seems like there is something new going on and something interesting with new challenges.”
Certainly one of their challenges this year was dredging the channel in what appeared to be a typical low-water season and the following week finding themselves dealing with river levels above flood stage. It just goes to show that Mother Nature maintains ultimate control of the ever-changing rivers we work to manage.
| Date Taken: | 10.24.2018 |
| Date Posted: | 11.06.2018 11:45 |
| Story ID: | 298965 |
| Location: | ROCK ISLAND, ILLINOIS, US |
| Web Views: | 207 |
| Downloads: | 0 |
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