Water Usage Optimization During Concrete Operations

Most of the currently ongoing Bechtel Mining & Metals (M&M) projects are being executed in arid or semi-arid countries, including Australia, Chile, Peru, and Argentina. Concrete operations at these sites entail a sizable scope of work—particularly at the early construction stages—and require a significant volume of water. In compliance with the concrete admixture design requirements, water consumption during the mixing stages is carefully monitored. However, it was observed that no such controlled measures were in place for other peripheral water consumption needs associated with concrete operations, including aggregate washing, cleaning concrete trucks inside and out, dust suppression on truck routes, and during curing stages. In view of the limited availability of water resources in these countries, appropriate water conservation measures using a Six Sigma initiative were proactively pursued. This paper addresses the various measures employed by Bechtel to achieve the metrics defined here as part of water conservation. The Six Sigma initiative investigated areas driving water optimization during our concrete operations beginning 2011 and intends to reduce the peripheral water usage by at least 30 percent or approximately 250 L of water per cubic meter of concrete fabricated. Based on our company's projected global M&M project workload between 2012 and 2015, it is being forecast that approximately 16 million m3 of concrete will be produced on our projects. Our water optimization strategy aims at conserving approximately 4,000 million L of peripheral concrete process water resulting in a potential cost savings of roughly $8 million USD on these efforts alone.