Significant Project Features:
- Soil-Bentonite Cutoff Wall
- Total Area: 168,700 SF
- Length: 2,410.0 LF
- Depth: 70 ft.
- Width: 3 ft.
- Permeability: <1.0×10-7 cm/sec
Project Objective:
To install a continuous, low permeability barrier to provide seepage protection and to improve the integrity of the dam foundation.
Description of Work:
Geo-Solutions was subcontracted to install a 70 foot deep Soil-Bentonite (SB) cutoff wall along the centerline of the proposed dam alignment. Geo-Solutions used a Komatsu PC 1250 LC equipped with a long boom and long stick attachment to excavate the 3-foot wide trench to design depths. A homogenous backfill mixture comprised of native site soils and bentonite slurry was blended through the use of tracked equipment. The SB backfill then placed into the open excavation, became the final barrier to the seepage of groundwater across the dam foundation.
As proposed by the Bayou DeChene Reservoir Commission on behalf of the Caldwell Police Jury, the future Bundick Lake will not only be used for recreational use and flood control, but as a supply of fresh water which is planned to produce over 6 million gallons of water per day.
Being responsible for the overall Quality Control (QC) of the cutoff wall installation, Geo-Solutions closely monitored and recorded several properties on a daily bases. A combination of field and laboratory testing was utilized in order to determine and verify the overall effectiveness of the final barrier. Utilizing flexible wall permeability testing, Geo-Solutions was able to achieve an average permeability of 1.3×10-8 cm/sec.
The project was completed on time, within budget and without a single incident. All crew members worked efficiently and safely as they met and exceeded Geo-Solutions’ Health and Safety standards.
Despite setbacks along the way, Geo-Solutions was able to overcome several the project challenges and considers this project to be a success.
Project Challenges:
- The remote location of the project site within the flood plain combined with extremely limited access during/following rain events proved to be a logistical challenge. Geo-Solutons’ crew and deliveries were required to traverse approximately 5 miles of dirt road in order to access the site.
- Geo-Solutions employed the use of our custom desanding unit equipped with a single Hydrocyclone to maintain levels of silt and sand suspended in the slurry to within the specified parameters.
- The Bundick Lake watershed is comprised of thousands of acres. Once complete, the lake itself will cover 950 acres and create over 30 miles of shoreline. Heavy rains were encountered throughout the majority of construction which lead to the flooding of areas within the dam and cutoff wall footprint. Geo-Solutions was required to relocate the laydown area and modify delivery schedules in order to continue work.
