Vertical Barrier Installation
East Hartford, CT: Soil Bentonite Slurry Wall, Stadium At Rentschler Field
Geo-Con installed a 44,000 vertical square foot soil-bentonite cutoff wall as part of the new football stadium for the University of Connecticut at Rentschler Field. The proposed stadium was being constructed on the site of an abandoned airfield known as Rentschler Field located on the East side of Hartford, Connecticut. To minimize construction cost, the field level and a portion of the seating of the proposed stadium is set below grade and below local water levels. The purpose of the 2,500-foot long soil-bentonite cutoff wall was to minimize water seepage and de-water below grade portions of the stadium.
The slurry wall was excavated 36 inches wide and keyed into the confining layer, which was determined to be a clay deposit on this project. The cutoff wall ranged from 18 to 25 feet deep with an average depth of 22 feet below the work platform.
The technical specifications for the project established a maximum permeability of 1 x 10-7 cm/sec for the soil-bentonite backfill mixture. The slurry wall was excavated predominantly into poorly graded medium sand and a sample of the clay key material was not available during the pre-construction phase. The preliminary mix design performed prior to the start of the project indicated that "dry" bentonite addition would be necessary to meet the permeability specifications, owning to the sandy nature of the backfill soils. Laboratory permeability tests performed on samples of the backfill mix were all less than the maximum allowable value of 1 x 10-7 cm/sec. Actual permeability values ranged between 4 x 10-8 and 2 x 10-8 cm/sec.