Posted April 22, 2019
The Western Dredging Association (WEDA) Midwest Chapter meeting took place in Memphis, Tennessee, from March 6 to March 8. About 70 members attended to hear presentations on safety issues, hydrographic surveying innovations and sediment analysis. The U.S. Army Corps of Engineers Dredge Quality Management Program and Corps district offices in the region also provided updates on federal projects and budgets.
The conference included a welcome reception on March 6 at the Embassy Suites Hotel Memphis and a lunch river tour and brewery trip after sessions on Thursday, March 7.
Electrical Resistivity Surveying: A Better Method for Identifying Subsurface Conditions
John Sawyer of ArcDMC Sediment Solutions, LLC presented on an innovative surveying technology for characterizing sediment conditions. The geotechnical surveys used electric resistivity to identify the subsurface, the characteristics of sediment and exact locations of contamination. The Aquares system and software was originally developed by Demco NV in Belgium. Arc Surveying & Mapping Inc. acquired the U.S. rights to the system in 2017. The same year, along with Shailesh Patel of Dredging & Marine Consultants, LLC, Sawyer formed ArcDMC Sediment Solutions, which focuses mostly on contaminated sediment surveys. The company is also working with various ports on providing geotechnical surveys for expansion projects.
For a test project in Rockledge, Florida, the electrical resistivity test was used on muck in the Indian River Lagoon. The test would compare various types of subsurface techniques to locate the muck and verify the accuracy of the resistivity survey. The Indian River Lagoon stretches 156 miles, and it is estimated that Brevard County waterways alone have more than 5 million cubic yards of contaminated muck.
“The previous thoughts on finding this muck were manual probes, which was ridiculous. They don’t work,” Sawyer said. “Sub-bottom profiling doesn’t work either because the sonar signal is impacted by the organics.”
Florida Tech, a university in the area, had started a program with students to measure muck in the river with probes, single beam dual frequency depth sounding and sub-bottom profiling. “They ended up assuming the entire bottom of the Indian River was muck,” Sawyer said.
Instead, Arc Surveying & Mapping used the electrical resistivity system to find better results. The technology has been previously used in the U.S. with the Corps for investigative hydrographic surveying for potential deepening projects, but the technology had not yet been used to locate the interface between contaminated and non-contaminated sediment, Sawyer said.
To ensure the testing accuracy, Arc conducted the project just as it would a standard project: establish horizontal and vertical control; do a bathymetric survey with a multibeam system and a dual frequency system; conducted a geophysical survey with the resistivity system with a 4D geophysical model, representing x, y, z and an ohmm value to represent resistivity; vibracore testing to verify the results; sediment characterization and some chemical testing on the sediment; then map the muck quantities.
The standard survey boat was equipped with RTK/GPS positioning and a dual frequency sonar depth sounder, in case the project encountered any suspended sediment. The system dragged a one-inch cable along the bottom with electrodes, which injects a current into the subsurface and records the data in ohmm values; the firmer the material is, the higher the ohmm value. It can generate a surgical dredging plan based on the interface between contaminated sediment and non-contaminated sediment, Sawyer said.
The test area was a 7,000-foot by 4,000-foot, 642-acre test area, which was surveyed in two days. Sawyer said the process is economical. Arc spent $60,000 on the test, which is about $93 per acre, including mobilization from the offices in Jacksonville, Florida; demobilization; hydrographic and geophysical survey; data processing; 4D model; and mapping and computing. The project identified 530,000 cubic yards of muck, which means the estimated cost of the survey was $0.11 per cubic yard, compared to the estimated dredging costs at $60 per cubic yard.
In comparison to traditional methods, “In every instance, the vibracore data matched the model,” Sawyer said.
The idea is that the x, y, z data of the contaminated and non-contaminated muck can be imported into the dredge system. “You can avoid standard dredging templates and only remove the materials that you need to remove,” Sawyer said.
Benefits of the system, as demonstrated by the Indian River Lagoon project, include identifying the locations and thicknesses of highly organic, nitrogen and phosphorus laden muck and eliminating the use of manual probes; identifying the total quantity of sediment to be excavated; and avoiding the removal of uncontaminated sediment by standard dredging templates, reducing the cost of treatment and disposal.
Arc also performed resistivity surveys for a widening and deepening project at Port Canaveral. For the test project, the port withheld its boring data until after the survey was done. “They didn’t want us to be able to manipulate any of this data. It was a great idea. But it was scary,” Sawyer said. Again, in every instance, the modeling matched the borings.
The process has also been used by Great Lakes at a project in Bahrain, and by the Corps for dredging projects at Kill van Kull, the Miami Harbor deepening, the Delaware River deepening and St. Johns River deepening.
Breaking the Mental Health Stigma and Company Safety Culture
Two speakers addressed important safety issues for the dredging industry. Margaret Davis of Hile Group started the presentations on Thursday with an important but often overlooked subject: “Hazard Within: Getting a Grip on Mental Health in Dredging and Marine Construction.”
“We focus so much on all of those specific job site hazards. There’s no doubt in our minds that dredging and marine construction is dangerous, and we do everything we can to protect folks,” Davis said. “But the hazards that you can’t see are really those working from within, not only with you but all those folks that you work with.”
She recognized that traditionally mental health has been a taboo subject for many businesses, especially in a male dominated industry. However, because of its prevalence, companies are beginning to address it with workers. The construction industry holds one of the top spots for occupations at risk for suicide. Other occupations that top the list include commercial fisherman, mechanics, electricians and farmers – they all share a common manual labor element and the potential for solo work and isolation.
Davis shared some statistics from the World Health Organization. One in four adults say work is a source of anxiety, and one in four of those with anxiety will tell their employers.
Davis presented an interesting work scenario: “This idea of sometimes people being shock absorbers for their bosses. ‘I am considered a more valuable employee the more I can absorb and take on to make my boss’ life easier’,” she said and wondered if some companies are rewarding people for not speaking up. Fortunately, World Health Organization statistics also indicate that 80 percent of workers who seek treatment see improvements.
She also addressed the concept of presenteeism: “People showing up to work and they’re physically there; they should be able to physically do the job, but just because they show up doesn’t mean they’re mentally capable to do it,” Davis said.
Work place suicide prevention best practices include education and advocacy and crisis management policies for when problems do occur. “It starts with leadership,” Davis said. She encourages companies to “break the stigma” surrounding mental health, by creating an open dialogue in the workplace and encouraging workers to speak up and look out for one another.
Stan Ekren of Great Lakes Dredge & Dock also spoke about safety: “On-Going Drive to World Class Safety.” He asserted that 95 percent of companies have a reactive safety culture, and 98 percent of all injuries are the result of unsafe human behaviors and actions. “Most of our companies concentrate on equipment, which is good. That’s how most safety cultures do work,” Ekren said. “But we’re forgetting about the human factor.” Additionally, the direct and indirect costs to companies can be staggering and even sink businesses.
Ekren said the safety culture has helped GLDD grow in the capital market because of the work it’s done over the last 13 years. Great Lakes started its safety culture in 1996. “It was a command situation, where you tell people how to behave,” Ekren said. “But it didn’t work. We weren’t really doing anything but checking the boxes.” The company tried different variations of safety programs in the late 90s and early 2000s, and in 2005, Great Lakes started the (Incident and Injury Free) IIF program. “Now we’re changing the culture,” Ekren said. Important components of IIF include everyone taking personal responsibility for safety; planning activities and asking questions; caring for coworkers; and speaking up about unsafe conditions. “IIF did change our culture. It did work,” Ekren said. “But we still have a long way to go.”
Ekren said the successes that Great Lakes has seen from its program include decreased insurance and employee recruitment or replacement costs; less managerial time spent on incidents; reduction in equipment damage; and improved employee morale and productivity.
J.F. Brennan Celebrates 100 Years and Other Presentations
This year, J.F. Brennan Co. celebrates 100 years in business. Andrew Timmis of J.F. Brennan presented an overview of the company’s long history and fourth generation ownership, starting with James and Eugene Brennan who started Brennan Brothers Construction in 1919. In 1959, the brothers went separate ways in business and Jim Brennan started J.F. Brennan Co. Roger Binsfeld, Jim Brennan’s son-in-law, also joined the business in the 50s. Today, J.F. Brennan focuses on marine, railroad and dam construction, barge transportation and environmental services.
Other presentations and presenters from the WEDA Midwest chapter meeting included: “Joint Expeditionary Base (JEB) Little Creek: Application of Active Materials as a Component of Contaminated Sediment Remediation,” by John Collins of AquaBlock; “Management of Dredged Debris during the Gowanus Canal Pilot Study,” by Darrell Nicholas of Geosyntec Consultants; “Sediment Dredging and Disposal” by Yamini Sadasivam of OMB, part of Ramboll; “Dock Wall Assessment: Condition Survey and Depth of Embedment Determination in Winter,” by James Wescott of Tetra Tech; “Evolution of Customized Sediment Sampling Approaches to Achieve Data Quality,” by Jed Sirk of Geosyntec Consultants; and “Proper Methodology for Environmental Sampling Prior to Dredging,” by Chuck Thibault and Blake Ellis of EarthCon Consultants Inc.
Vern Gwin, program director, Corps National Dredging Quality Management (DQM) Program, gave an update on the program – the DQM viewer, security access, pipeline monitoring and specs for non-nuclear density meters.
A new DQM viewer V3.0, which shows ongoing dredging monitoring for hopper and pipeline dredges, was released. The original viewer showed only hopper dredges. When pipeline monitoring went active, the Corps developed another viewer for that. The newest viewer combines and enhances the two.
The Corps is doing more and more pipeline monitoring and working with new customers to fine tune that process. The DQM program added two new employees to handle that work load. More districts have also asked for specialized pipeline data, and DQM wants to be able to handle more analysis requests. “If you think of some special analysis that you’d like on the data, we can share with you what some of those things have been in the past and maybe those can help you analyze your dredging projects,” Gwin said.
The entire system was stored on Corps servers, but as it has grown that has become difficult to manage. The program is in the process of moving to a cloud-based system. As of early March, it was about half way done, Gwin said. The transition should mean increased performance for the system.
The Corps is also doing a hopper dredge utilization study to show if the dredges are being used efficiently or if the Corps should look at investing in a new hopper dredge to meet future needs. Gwin said the DQM data has been very helpful in those evaluations.
With added security contractors, the Corps can now offer contactors access to the system to see individual projects. New updates to the program also allowed contractors to use non-nuclear density meters, instead of traditional methods for measuring slurry density, and meet the DQM specifications for monitoring.
Each Corps district in the region also provided updates on FY18 and FY19 contracts and the regional dredging programs.