Slurry cutoff walls are constructed by excavating narrow trenches under bentonite slurry and then backfilling (displacing) the slurry with higher gravity impermeable material to create subsurface barriers that prevent the lateral flow of groundwater. They are used to contain the migration of contaminated groundwater; reduce the permeability of storage impoundments such as tailings dams, ash ponds, or wastewater treatment ponds; and to prevent under seepage in levee and dam construction. Great Lakes E&I has constructed more than 21 million square feet of slurry cutoff walls, placing us at the forefront of the industry with regard to capability and experience in this type of construction. Design permeability and strength requirements as well as native soil and groundwater conditions influence the composition of the engineered slurry backfill. Great Lakes E&I’s slurry wall construction capabilities include the ability to design and construct soil-bentonite, soil-attapulgite, soil-cement, soil- cement-bentonite, cement-bentonite, and slag-cement-bentonite cutoff walls. Additional expertise includes the installation of biopolymer collection trenches and permeable reactive barriers (PRBs).
NATOMAS CROSS CANAL LEVEE IMPROVEMENT PROGRAM
Great Lakes E&I continued a history of award-winning performance, receiving the American Society of Civil Engineers (ASCE) 2010 Outstanding Project of the Year Award for the Natomas Levee Improvement Program. The Natomas Basin is part of the Sacramento River Flood Control Project (SRFCP), an integrated system of levees, nearby bass channels and dams, constructed to protect communities in the Sacramento Valley from flooding. The levees were constructed with unsuitable materials that proved to be extremely porous when subjected to sustained high flows.