As increasing numbers of building owners realize that employing green strategies makes sense from both environmental and economic viewpoints, they’ve been creating and retrofitting their buildings with a variety of water-saving fixtures and systems – everything from waterless urinals to rainwater harvesting tanks. This has been the trend regardless of whether they are pursuing third-party green certification for their properties, as easy installations and management practices are all it takes to achieve the money and water savings.
But construction-phase water – another large opportunity for water savings – has remained largely unaddressed.
Why is that the case? Because it is difficult to measure? Because those using the water don’t pay the bill? Because we largely lack incentives or disincentives to curb construction water use? All of the above.
Absent of a scorecard or a mandate, here are some actions that all active construction sites – for both building and infrastructure projects – can take to reduce water use and ease the burden on our water resources:
First, focus on reducing wasted water. Leaky hoses, and outdoor taps left on are the first thing to target. With a little oversight by those already in the field, this no-cost step can not only conserve water, but also start to create an onsite culture of water conservation.
Our moveable 10,000-gallon water tank at Interstate 275 collects water to reuse for dust control.
Next, look for alternative sources available to you on site. Catch basins can be a source of grey water for dust control. For example, the Skanska Ajax joint venture rebuilding a four-mile stretch of Interstate 275 through Tampa uses a moveable 10,000-gallon water tank that they tow to various on-site storm water detention ponds to collect water for reuse for dust control, and to ensure proper moisture levels in soil being compacted. However, in a drought there is likely no excess water to use, so alternative substances – such as biodegradable spray-on adhesives – can eliminate repeated spraying of potable water.
Our concrete chute wash-out system at Elizabeth River Tunnels works to capture, retain and re-use water.
Lastly, look for better engineering controls, especially those utilizing closed-loop solutions that capture, retain and re-use water. SKW Constructors, the joint venture building the $2.1 billion Elizabeth River Tunnels project in southeastern Virginia, uses two self-contained concrete chute wash-out systems. These collect the waste material, capturing leftover concrete in a bin to be recycled and filtering the water so it can be reused with the next concrete truck. At the end of the day, the water can be pumped into the last mixer truck to be taken to the concrete plant for proper disposal. This system eliminates the use of large amounts of water, as well as the expense of disposing of wash water on site. Similar closed-loop wheel washing systems can be used as well. If municipal grey water lines are available, tap into those to further reduce on-site potable water demands.
With all of these strategies, the most important aspect is not to implement them in a vacuum. Be sure to inform your project teams as to what is being done and why it’s important to reduce water usage. Perhaps an incentive program could be designed around this to develop solutions that further drive down demand.