Conway, SC: DSM Soil-Crete Shear Walls, Horry County Landfill
The original project involved the installation of 20 soil-cement shear walls at the Horry County Landfill. Shear wall construction was achieved by using the Deep Soil Mixing (DSM) method to provide the structural support that was needed to excavate peat deposits located directly below an existing landfill cell. Each shear wall was 25 feet long 3 feet wide and averaged from 65 - 77 feet below ground surface (bgs). Each wall was aligned parallel to each other with a 15 foot space between each wall.
After mobilization, 3 test walls were constructed each with different cement to soil ratio (18%, 20%, and 22%). The test program was used, as a gauge to determine which mix design would best meet the projects strength specification of 360 psi for each wall after 28 days.
Upon completion of the test program full-scale production began using the 20% cement to soil mix ratio as determined from the test program. During the full-scale production additional walls were required to be added in certain locations between the existing walls. A total of 12 additional walls were added where the minimum strength requirement was not achieved due to abundant amounts of subsurface peat deposits and acidic ground water conditions (these were not known to have existed in these areas)