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DEEP SOIL MIXING, POLYMER TRENCH Project
Tarrant City, Alabama
This 1-1/2 acre industrial site handles the characterization, transportation, and disposal of various by-products for the local industries. To keep up with market demands, the facility needs to be renovated and expanded. However, the soils were impacted with chlorinated solvents, hydrocarbons and trace metals.
Project Goals
The facility goals for expansion include:
- Remediating all soils surrounding the building footprint;
- Installing 9 injection trenches, approximately 30 to 70 feet long and 27 feet deep;
- Completing the remediation and new construction without impacting current on-going operations.
These goals are being accomplished by working two shifts with two oversight companies at this active facility.
Scope of Work
The original remediation approach was to perform a mass excavation and replace the area with suitable backfill. However, the cost was not effective since the impacted material would need to be incinerated. Deep Soil Mixing was then selected as an alternative solution. This approach will remediate the impacted soils while at the same time achieve greater soil strengths for the new construction.
Prior to arriving on site, RECON developed a mix design to determine additive rates necessary to achieve the performance criteria, which includes a minimum unconfined compressive strength (UCS) of 50 psi in 14 days and a maximum permeability of 1 x 10-7 cm/sec. The mix design chosen includes adding 10% cement.
RECON is performing in-situ solidification/stabilization to approximately 15,000 cubic yards of impacted soil using our own Deep Soil Mixing Rig. The depth of the stabilization will extend to 14.5 feet below ground surface. To account for a swell factor, 7,500 cubic yards will be removed for off site disposal.
RECON is also installing approximately 10,800 square feet of injection trench using the open cut method and the bio-polymer slurry trench method of construction. These trenches will include pipe and risers for the groundwater remediation effort.
Work is being completed in three phases in order to minimize disruption to new construction and ongoing
facility operations.
Ancillary Tasks
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Additional work to complete the project includes:
- Grading the work area for management of the surface water;
- Demolishing various below grade structures inside the footprint, including sumps, culverts, and drainage piping;
- Excavating surface soils and grading stabilized soils to manage the swell and maintain the original grade; and
- Controlling vapors by using suppressant foam and plastic sheeting.
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Project was successfully performed under challenging conditions due to limited access and active facility operations | | | 
Secant wall construction is common for soil retention systems; but the application at the New Haven School District was, perhaps unique. Secant pile technology was selected to expedite the schedule and improve on the cost of the project. The school district had 10 months to build a 6-million gallon stormwater run-off holding tank. The 140-foot by 240-foot tank was to have a bottom elevation 25 feet below ground surface (bgs) and be adjacent to the property line. Additionally, the water table was at 10.0 feet.
Anchors and Tiebacks