Project: Westside CSO Tunnel Project

Overview

NGI provided laboratory slurry testing in support of the Westside CSO Tunnel Project. At the request of Impregilo/Healy J.V. NGI fabricated a specialized permeability test apparatus required by the tunnel slurry designer. NGI then proceeded to secure and process gravel for completion of the tests. Up to 9 cubic feet of gravel was broken down to the specified grain size. Twenty-eight permeability tests were then completed. The systematical test program of varying additives to the slurry mix was completed to minimize the loss of slurry at the tunnel face and to improve the tunnel face support during tunneling with the boring machines. NGI’s project geotechnical engineer interfaced between the laboratory manager and the slurry designer. Associated testing included grain size distribution, density, viscosity, and yield point.