Biopolymer Trenches

Biopolymer trenching is an innovative technique for installing permeable drainage trenches. These trenches use synthetic biodegradable polymer water based slurry to support the trench walls. This method provides several advantages over traditional construction techniques, particularly for deep applications that extend below the groundwater table. Secondly, the biopolymer stabilizes the excavation walls resulting in a safer project.

Biopolymer trench excavations are typically constructed using hydraulic excavators with widths varying from 1.5 to 3.0 feet. Excavation depths in excess of 100 feet are possible with this technique.

These trenches facilitate the installation of manholes, sumps, and perforated horizontal and vertical piping to allow extraction, collection, recharge or injection to support remediation activities. In addition, they can be used for in-situ remediation processes including air sparging, carbon adsorption and chemical treatment such as dechlorination. In some cases, the excavations are lined with filter fabric or impermeable down gradient membranes to increase their effectiveness.

RECON has used biopolymer slurries to construct:

Recovery trenches;
Permeable reactive barrier walls;
Hanging curtain walls; and
HDPE curtains.

Additional information on biopolymer trench construction is located at www.BioPolymerTrench.com.

Biopolymer Trenches Case Studies

SKULL CREEK OIL SEEPS
Cushing, Oklahoma

Remedial Construction Services, L.P. (RECON) was contracted to perform an interim remedial measure at former refinery in Cushing Oklahoma. This work was performed as part of an ongoing refinery closure under the regulatory of the State of Oklahoma. In order to divert the flow of a creek impacted with oily wastes, RECON was selected to convert a portion of an existing meander into a interceptor/treatment trench. This action allowed waters to bypass the impacted creak meander.

Channel Construction
The initial phase included creating a new channel, approximately 300 feet in length with 3:1 slopes and bottom grades to meet the creek flow modeling requirements. Work included:

Surveying and laying out the channel location;
Clearing and grubbing the work area;
Excavating approximately 14,000 cubic yards of soil to create a new channel;
Sloping and stabilization of banks and the bottom of the channel; and
Installing diversion wing walls to route the water down the new channel.

The wing walls were installed with close detail to radius and obstruction, so as not to diminish the natural flow of the creek and minimize future erosion. RECON contoured the wing walls and covered them with 18-inch riprap armor and a 3:1 slope.

"Despite an abnormal amount rain, this project was completed on time and on budget"

Interceptor Trench Installation
In order to install the interceptor trench, RECON meticulously removed approximately 4,000 cubic yards of oily waste from the meander using a 300 series track mounted excavator and off-road articulated dump trucks. The excavated soils were dewatered by segmenting and depositing in a frac tank and transferred to the onsite waste staging area.

Subsequent actions included:

The placing and compacting of 16,000 cubic yards of interceptor trench soils in the creek meander.
Mixing and placing bio-augmented solution consisting of compressed cow manure, gypsum, wood chips and limestone cobbles in the trench. In order to promote good aerobic activity, the solution was covered with limestone.
Installing of a weir structure and sump on downstream side of the trench.
Finish grading of treatment area.

Restoration
To complete the project, RECON planted 422 trees at numerous locations around the work area and seeded the site with native grasses as part of an agreement with the US Army Corps of Engineers, who manages the creek.

INTERCEPTOR TRENCH
LNAPL AND PHENOL SEEP RECOVERY TRENCHES
Duncan, Oklahoma

Anticipated migration of groundwater toward an adjacent State waterway resulted in Remedial Construction Services, L.P. (RECON) being retained to install two interceptor trenches and associated recovery systems. Former refinery operations resulted in two independent groundwater contamination plumes at two distinct depths below grade. LNAPL Trench Construction
The light non-aqueous phase liquids (LNAPL) trench measured 1,000 linear feet and 25 feet in below grade depth. Project specifications mandated that synthetic slurry be used to maintain trench integrity. RECON´s application of the synthetic slurry was successful; exhibiting good characteristics, in spite of the above-average rainfall throughout the duration of the project. Interlocking 80-mil high-density polyethylene (HDPE) panels were fabricated onsite and installed in the trench to serve as the horizontal barrier. Recovery wells were installed for future use and the trench was backfilled with gravel and topped with general fill.

Phenol Trench Construction

The Phenol trench was located next to a former landfill. After re-aligning the trench several times, the final dimensions were 725 linear feet by 35 feet below grade. Soils segregation was necessary on this trench. As the impacted soils were excavated, they were transferred to a lined staging area for disposal. The non-impacted soils were staged along the trench alignment to be used later during backfilling operations. To serve as the horizontal barrier, interlocking 80-mil high-density polyethylene (HDPE) panels were fabricated onsite and installed in the trench. Future use recovery wells were installed and the trench was backfilled with gravel and topped with general fill.

Challenges

Challenges associated with this project included working near an active rail line and former landfill; coping with a remote water source; and managing extensive stormwater requirements next a State waterway. Crews maintained the trenches through above average precipitation and the Thanksgiving, Christmas and New Year’s holidays.

Project was completed near an active rail line, and a remote water source that required extensive stormwater requirements.

Biopolymer Trenches

Biopolymer Trenches Case Studies SKULL CREEK OIL SEEPS Cushing, Oklahoma

INTERCEPTOR TRENCH LNAPL AND PHENOL SEEP RECOVERY TRENCHES Duncan, Oklahoma

Phenol Trench Construction

Challenges

Biopolymer Trenches Case Studies

SKULL CREEK OIL SEEPS
Cushing, Oklahoma

INTERCEPTOR TRENCH
LNAPL AND PHENOL SEEP RECOVERY TRENCHES
Duncan, Oklahoma