"Green" concrete practices

Concrete Construction, April, 2003 by Lance Boyer

Being an architectural concrete contractor in Southern California, or anywhere in the United States for that matter, increasingly requires an in-depth knowledge of environmental regulations. Architectural concrete contractors modify concrete surfaces using techniques and finishes that often produce runoff we cannot legally discharge to a storm drain system. We are the ones who are liable for environmental compliance on the jobsite for our work. If we fail to comply, we may face hefty civil and even criminal charges, so it's in our interest to be proactive. My company, for example, has taken steps to educate architects and owners about "green" alternatives, to use nontoxic products, and to control cleanup and disposal.

Regulations require containment and further processing of byproducts from acid washing, chemical staining, retardant or washed finishes, and excess release agent from cleaning stamped concrete, before they can be put into a landfill or discharged into a sanitary sewer system. In California, restrictions are so severe that homeowners cannot even legally hose down a driveway and let the water run into the gutter. While the "environmental police" are not giving tickets to homeowners just yet, they do view commercial entities, including contractors, as a threat to the stormwater system. Our jobs are often in very visible urban locations where everybody is watching.

Whenever possible, my company uses nontoxic retardant chemicals in lieu of acid washing or sandblasting. These solutions are available from several manufacturers in different strengths to achieve the required depth of etch and a finish that meets the original specification. More importantly, the runoff is not caustic, no dust is produced, and our employees do not have to handle a toxic material. However, we are still required to contain the runoff because it contains cement and fine sediments.

On a shopping center project we did recently in Irvine, the specification called for an acid-washed finish. We knew that The Irvine Co., the owner and a large developer in Orange County, is committed to environmental compliance. In addition, general contractor Turner Construction Co. was concerned about acid runoff damaging adjacent planting areas. We proposed substituting a retardant solution. Irvine and Turner were receptive to the proposal and pleased with the end result.

We often recommend these alternatives to the architect, ideally in the planning stages of a project. The first question is: Will it cost more? The answer is no. Architects also may doubt whether the final appearance will match the specification. We will produce an 8x8-foot mock-up at the jobsite so the architect and owner can review the finished product before work begins. We also explain the environmental regulations that apply to this work.

We rarely employ acid washing any more, and never where runoff will enter the storm drain system. We do sandblast on occasion, as when topping slabs over waterproofing membrane where runoff would create a problem, or when the architect is adamant about the sandblast texture.

We established a separate service company to provide environmentally safe cleaning that complies with local regulations. Equipped with specialty equipment, this service company cleans our concrete work after construction is completed and in many cases maintains the paving at the property. The cleaning system, which uses a waste recovery and filtration system, was developed specifically to clean concrete or other hard surface paving. Hot water is transported from the self-contained truck to the cleaning equipment, and then the grime, debris, and dirty water returns to the truck for filtration via a vacuum system. A six-stage filtration process transforms the recovered polluted wastewater into graywater that is discharged at an approved disposal facility.

As environmental regulations become more stringent, we must adapt our business approach to comply and increase our contribution toward the goal of a cleaner environment.

--Lance Boyer is president of Trademark Concrete Systems (www.trademarkconcrete.com) and Hardscape Renovations (www.hardscape.info).

Boyer can be reached at lance@trademarkconcrete.com.