22Feb 2013

Uretek Builds Groundwater Cutoff Curtain for FDOT Project

By Robert Armstead

Uretek Holdings recently installed a 290 L.F. in-situ grout wall along Blue Heron Boulevard in Riviera Beach, Florida, for the Florida Department of Transportation (FDOT). The wall is designed to prevent the migration of a ground water contamination from a gasoline leak at a former gas station to a DOT construction site.

Because Uretek was able to build this grout wall for us, it saved us time and money not having to deal with this ground water contamination at our site.

While performing improvements to SR-5/US Highway 1, one element of particular concern was installation of a new storm drain system. Installation of this system requires dewatering utilizing a well point system for proper installation. Due to the proximity of groundwater contamination on a parcel adjacent to the FDOT right-of-way, the dewatering operation presented a serious impact as it would likely cause migration of the groundwater contamination from the adjacent parcel, onto the FDOT right-of-way and into the dewatering system.

“In actuality, the above scenario presented serious implications if handled in a traditional manner, which would be for the FDOT to engage the services of a remediation services contractor to perform treatment of the dewatering/well point system discharge,” explained Robert Moody, URETEK Holdings’ COO.

The first issue is that the treatment operation itself is very costly, time-consuming, and required a large footprint to stage all of the necessary equipment for treatment. The second issue was that contamination was drawn from the adjacent parcel and onto the FDOT right-of-way; thereby, contaminating State property. The third issue was that with the contamination being moved by the dewatering operation and drawn off the adjacent parcel, it invalidated contamination assessment and on-going remediation activities conducted on the adjacent parcel, requiring new assessment activities and possible re-engineering of remediation activities.

In an innovative approach to this problem, the State approached URETEK to install a groundwater cut-off curtain to create a hydraulic barrier between the right-of-way and the adjacent parcel. URETEK installed a 290 L.F. grout curtain utilizing its 486STAR rigid structural geotechnical polymer. The polymer was injected into the soils on a 3.0′ vertical grid pattern directly proximal to the contamination, starting at an elevation of 8.0′ below existing land surface (BLS) and terminating at 20.0′ BLS. When installed the polymer expands rapidly, creating an in-situ stabilized mass that restricts the movement of groundwater. Due to extensive and unknown utilities in the installation area, the injection rods used to deliver the polymer were installed using hydro-lances to “jet” past any potential utilities.

The entire grout curtain was installed without incident in five days utilizing 9,800 pounds of polymer. The work was performed well in advance of construction and will not contribute to any delay to the project. FDOT will closely monitor the dewatering system and adjacent groundwater monitoring wells during construction to determine the effectiveness of the URETEK solution.

“It was a big project, but our team stepped up to the challenge and completed it successfully within the deadline,” said Robert “Bob” Moody, Uretek’s Chief Operating Office. “We were happy we could help out the Florida DOT and complete this repair for them at a fraction of the cost of any alternative solution.”