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GEOTECHNICAL CONSTRUCTION American River Watershed Project Construction of 1,100,000 square feet of soil-cement-bentonite cutoff wall to a maximum depth of 70 feet. The cutoff wall, with a maximum permeability of 5x10-7 cm/sec and an average unconfined compressive strength of 35 psi, protects the stability of an existing levee by providing isolation of river water seeping into the levee and its foundation soils. The cutoff wall was constructed during the period of April 15, 2000 to October 29, 2000. Three large excavators capable of excavating to maximum depths of 70 feet were utilized working six days per week to complete the 4.5 miles of cutoff wall before the mandatory completion date of November 1, 2000. Also, the scope of work included installation of a 48" HDPE drainage outfall, accommodating existing utilities and construction of a clay cap.
Geo-Con prepared the soil-cement-bentonite backfill in 30 cubic yard bins adjacent to the trench. This innovative production method minimized equipment traffic on the levee and areas of disturbance.
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