Environmental responsibility is not merely a sign of good corporate stewardship. Not keeping plants in good operating condition is against the law.
One activity under increased enforcement is how process water is handled before and after concrete has been delivered.
In many areas of North America, producers traditionally rely on plant haul road surface grading, retaining sumps, and evaporation to control potential process water emissions. But as local and federal environmental enforcement agencies increase their regulatory reach into our industry, these traditional practices are not enough.
Roger Engelsgaard, vice president of operations for Concrete Washout Systems Inc., Wilton, Calif., offers some insights on how much process water and washout concrete needs to be contained. His firm developed a system that controls, captures, and contains all concrete washout wastewater and material. He estimates there's enough leftover concrete generated annually to pave an eight-lane highway 175 miles long.
On each of the 34 million loads delivered each year, about 1/16 cubic yards of residue remains on each delivery chute. This totals more than 4 million tons of concrete. Producers use more than 240 million gallons of water to keep their trucks clean.
To help producers better prepare their operations for the eventual upgrade of their best practices, we offer some innovative systems to help improve their overall water management programs.
Easing the flow
When a job shuts down, the cleanout rack becomes a popular place. In many plants, the recycler intake set-up only allows room for one or two trucks to wash out at one time. Drivers wait or are diverted to nearby sumps.
To eliminate this expensive non-bill-able waiting time and to return trucks into service faster, engineers at Liebherr Concrete Technology Co. introduced their LDP Concrete Reclaimer Buffer. The unit can be added to an existing Liebherr concrete reclaimer or combined with any standard concrete reclaiming system.
The buffering equipment has several advantages. First, it's fast, as the system can accommodate up to six discharging mixers simultaneously. Because it is designed to act as a gob hopper for the washout, drivers can discharge as fast as possible into the buffer's holding tank.
An even greater advantage is its ability to temper or condition the consistency of the washout. The LDP Buffer discharges the gathered washout at a controlled rate and consistency into the reclaimer. The reclaimer performs more efficiently by avoiding the volume surges and inconsistency of the feed material.