Description of Work:
This contract is a continuation of a series of slurry walls that Geo-Solutions has participated in for the flood protection of both commercial and residential properties within Sutter and Butte Counties, located in northern California. This area is at high risk of flood damage, only exceeded by New Orleans, Louisiana. Geo-Solutions teamed with local contractors to complete a number of projects. The non-flood season is limited, so work often continues 24 hours per day, 6 days per week.
Geo-Solutions was responsible for providing all labor and equipment required to complete a portion of slurry wall installation, and for the other portion, Geo-Solutions teamed with local contractors to provide technical assistance in the form of Quality Control and Supervision. The specified requirements for the Soil-Bentonite (SB) cutoff wall were a minimum trench width of 36-inches, SB backfill permeability of less than 5×10-7 cm/sec and fines content between 20%-60%. Other acceptance criteria included; in-trench slurry densities no greater than 85 pounds per cubic foot (pcf) and a SB backfill slump between 4-7 inches measured using a slump cone. Geo-Solutions utilized custom long stick and boom attachments along with a Komatsu PC1250 excavator to permit the excavation of a vertical trench 74 feet below the working surface.
Throughout this project, Geo-Solutions was presented with various challenges. The limited construction season, working on the Northern California levee systems required a 24 hour schedule, 6 days per week during the majority of the project. Geo-Solutions used both local labor and full time field employees to complete the installation. In sections of the project, Geo-Solutions encountered delays due to the discovery of cultural sites and enviromental buffer zones established to protect various wildlife native to the area. By working with the local agencies, Geo-Solutions successfully excavated through the areas with minimal disturbance.
Excavation and backfill activities were completed on time and final backfill media met or exceeded all of the client’s design requirements.