Shoring, Dewatering In Flood Zone

April 2010 Vol. 65 No. 4

Water, water everywhere
“It was a unique challenge for us,” said Gray “The soils here are tough, and water begins to flood almost immediately after digging begins.” Mabey’s proprietary Titan struts and corner braces provided lateral stability during excavation and once the sheets and frames were in place, DooleyMack excavated and dewatered the pit in two, 175-foot by 62.50-foot phases. In spite of the normally water tight interlocking sheets and pumping equipment, water was intruding at a rate that exceeded dewatering in each of the excavation’s sections.

“It was amazing; several feet of water would be pumped out each day but tidal changes would cause more water to flood in overnight. It was definitely an uphill battle,” explained Gray. To combat this, Dooley Mack hired divers to assist in the installation of the building's concrete pilings and support systems before a 4-foot thick concrete seal slab was poured at the base of the excavation utilizing the tremie method. This stopped ground water from penetrating the excavation and allowed work to continue. When the first half of the excavation concluded over the summer, DooleyMack moved on to the second phase of the pit and again, Mabey’s framing and struts were used in tandem with the contractor’s sheets. The excavation phase of the project wrapped-up in early December before Mabey’s modular frames and equipment were removed. To date, it is the largest and deepest excavation on record in South Florida.

Mabey Bridge & Shore Inc., (800) 956-2239,