LOUISVILLE, Ky. — After the discovery of an undocumented dump site put a hold on a high-profile U.S. Army Corps of Engineers (USACE) Louisville District project at Fort Campbell, Ky., construction site preparation resumed May 3 — 30 days earlier than initially expected and at a fraction of the projected cost.
During site preparations in late January to construct a battalion headquarters and multiple company operations centers on Fort Campbell, waste was discovered below the surface.
Even though the waste was determined to be primarily construction-related material, the site had to be remediated by virtue of Kentucky state law which forbids stockpiling trash in an open area that is not an approved landfill.
Thanks to a collaborative effort between the USACE Louisville and Fort Worth districts, U.S. Army Environmental Command, the Directorate of Public Works and environmental managers at Fort Campbell, and on-site construction managers, the environmental investigation work was completed in one day and resulted in a $9 million cost-avoidance.
“We wanted to start as quickly as we could, because when [the Louisville District’s construction division] suspended construction, it cost $5,000 per day, and they estimated 90 days of downtime,” said Glen Beckham, Louisville District project manager.
The initial idea was to perform a series of test trenches. This involved using a backhoe to dig around the area at random to identify where the problem might be—but construction division expressed concerns about digging up the area, Beckham said.
During a meeting to discuss the project, it was asked if there was any way to use a geophysical device to identify where these areas might be instead of trenching everywhere. Geophysical devices are normally used to locate munitions items because they detect magnetic anomalies.
“I said I’ve never been involved with a project where they have done that, but maybe so,” said Beckham. Beckham knew a geophysicist working at the Corps’ Fort Worth District, Eric Kirwan, and the two of them along with Eric Cheng, Louisville District environmental engineer and Nathaniel Peters, Louisville District senior technical manager and contracting officer representative began to investigate Nation’s idea.
The first method they looked at was to use a ground-penetrating radar that measures soil densities.
“But it was identified that clay acts as a barrier to the radar and is not effective,” said Beckham. ”This area is known to have clay in the soil, so a better device was identified called an EM61.”
The EM61 measures magnetic anomalies and soil density disturbances, is not affected by clay and can be geo-referenced to centimeter accuracy. So, it was determined that using an EM61 would be a very good device to use for the investigation.
The project was originally projected to take 10 days to perform the geophysical investigation and five days to perform verification. Verification would be done by digging a limited number of test trenches to confirm what the geophysical results told them.
“We set some aggressive goals to do the geophysical in five days and do the trenching in two days,” said Beckham. “We were in the field three days after the contract was awarded which was very fast. So this work was initiated and completed within three days after the contract award.”
The project began in early March, since it took about a month to assess the site conditions, award the contract and get out into the field.
The contract was awarded to Battelle of Oak Ridge, Tenn., which is a subcontractor to GeoConsultants, LLC.
“GeoConsultants really helped us get out there and get things done fast,” said Peters. They were also able to get the contractors out to the site on a Saturday instead of waiting until Monday.
“These guys came out and knew just what they were doing,” said Beckham. “They hit the ground running. They used an ATV (all-terrain vehicle) to pull this device over 100 percent of the area, and they basically did it all in one day.”
After the geophysical investigation was completed, it was determined that the main building design was sitting right on top of the dump site, which was actually three times larger than what was first suspected after initial trench testing and 20 feet deep.
“Instead of being 30,000 cubic yards and costing $3 million in remediation costs, it was 90,000 cubic yards and $9 million,” Beckham said. “That’s what this investigation revealed in one day.”
Designers decided the best approach would be to shift the whole design 185 feet southeast into a clean area away from the dump site, avoiding virtually all contamination. Initially it was anticipated that there would be 90 days of construction downtime, but the contractor was able to be remobilized 30 days earlier than expected.
“They avoided a $9 million remediation and we’ve estimated the remediation cost to be $550,000 or less,” Beckham said. “We think the remediation time will require less than two months which is less time than we originally thought, and because of the locations, we can remediate them concurrently with construction. So that’s going to save time and money.”
The effectiveness of the EM61 for this geophysical investigation has prompted discussions on potentially implementing its use as a standard practice.
“Aside from the cost-savings,” Beckham said. “I think the other great success was the value of the collaboration on it and the way we worked so well with the Army Environmental Command, with Fort Campbell staff and with the Corps of Engineers staff to quickly reach a solution.”