Case Studies
Golden Pass Lng Project
Sarbine Pass, Texas

Remedial Construction Services, L.P. (RECON) was contracted to prepare a site for the construction of a Liquified Natural Gas (LNG) terminal. The site is located on the Port Arthur Ship Channel and was selected because of its remote location and raised elevation. However, these benefits created challenging construction issues. The remote location is in the middle of 800 acres of wetlands and the raised elevation is the result of a 10-foot thick pile of dredge materials deposited by the US Army Corps of Engineers. The end result was the site soils consisted of low bearing capacity silts and clays with strengths from 0 to 3 psi unconfined compressive strengths (UCS).

Scope of Work
The scope of work included:

• Stabilizing over a 500,000 cubic yard area of zero strength soils;
• Cutting and filling over 400,000 cubic yards of material;
• Constructing 10 acres of laydown areas;
• Constructing 20,000 feet of site and plant roads;
• Restoring 350 feet of shoreline;
• Constructing 5,000 feet of dikes along around the perimeter and the LNG tanks;
• Controlling sedimentation and erosion;
• Reclaiming 33 acres of wetlands;
• Installing underground utilities; and
• Constructing temporary and permanent drainage systems throughout the plant.


Stabilization
RECON used a proprietary blend of fly ash materials to strengthen the site soils. This material was mixed using RECON-owned excavators with mixing buckets. This technique was originally developed for stabilization activities within the environmental industry. RECON was able to stabilize the material to 25 psi.

Site Improvement
RECON performed a grade rise in the 30-acre wetland area under a FERC permit. The area was originally at elevation 0-1 MSL and was raised to elevation 8. The first step involved setting up erosion and sediment control systems throughout the wetlands prior to dewatering. This was accomplished using marsh buggies and silt fence. The area was then dewatered using bleeder ditches that drained into sump stations and pumped through riprap dissipaters. Once dewatered, the area was raised by placing geogrid, 4-feet of flexible base, and finally 4-feet of compacted fill.

A perimeter dike was designed to protect the facility against a storm surge resulting from a Category 4 hurricane. Shoreline restoration activities were conducted in order to reclaim shoreline lost during Hurricane Rita.

Case Studies
UNOCAL NORTH AREA CLOSURE
Nederland, Texas

• RECON utilized an excavator mounted on swamp pontoon tracks to install several drainage ditches in excessively soft sediment/ sludge. This coupled with simple sump dewatering techniques proved to lower the water elevation in the sludge, forming a two-foot thick crust. This allowed low-ground pressure dozers to traverse most of the area. Other very soft areas within the impoundment were stabilized using fly ash, a by-product generated from a local power plant. Long-stick excavators were used to mix the fly ash with the sludge. By excavating drainage ditches, RECON used 50% less fly ash during the project. In addition, we were able to use normal strength bi-axle geogrid in lieu of high-strength.
• Clean sand was to be placed above geogrid for purposes of serving as a pressure-relief layer and GCL bedding layer. Since the drainage ditches were installed, sand was no longer required to serve as a pressure-relief layer. RECON substituted a more readily available sandy clay [60-40] material in place of the sand. RECON crews installed both geogrid and GCL.
• In order to speed-up the construction schedule to receive a minimum of 200 loads of dirt per day, RECON developed and operated a borrow pit and purchased 17 dump trucks. With the help of local hauler, RECON was able to haul in excess of 400 loads per day to UNOCAL.
• Last but not least, our field crews make the difference. Much of our success on this UNOCAL project was directly attributed to their ingenuity and willingness to get the project done in a safe and quality manner, productively.