Nick Dobrez | August 21, 2018
A company was selected to run utilities under the newly expanded portion of Interstate 405 in Los Angeles, CA. High pressure water evacuating is used to “drill” tunnels under the highway. This process produces a very thick mud and water slurry that can not be discharged on-site. The slurry is collected and brought to a central facility on the construction site with a vactor truck, allowed to settle in a weir tank, then both mud and water are sent off for treatment or disposal. This process costs the construction company over $228,000 each month on treatment.
HaloKlear created a new and improved system to dewater the muds and produce water that can be reused in the high pressure jetting process or for site dust control. After initial testing, HaloKlear recommended the use of a new, dry flocculant, TW-10, to dewater the sludge. As the water is pumped from the vactor truck, it is dosed with TW-10 using a venturi. The treated slurry is mixed into a weir tank and the flocced sediment quickly settles to the bottom of the tank. The water is removed from the tank and pumped through filters. The solids on the bottom are removed from the tank using a conveyor belt system that uses low energy.
After treatment and filtering, the water measures at a single digit NTU. This treated water is reused in the tunneling process or for site dust control. The solids concentration is improved from 25% to 60% solids and easily moved using a backhoe. The solids are stored on-site and used as backfill on the project. The company is saving 65% each month with this new and improved process.