Sampling Concrete for Asbestos
For years, concrete floors, walls and footings were not considered to be “suspect asbestos-containing materials.” Concrete was often not even sampled during a standard asbestos survey. Some time ago, the SCAQMD confirmed that concrete was indeed a “suspect material,” so we began collecting surface samples from accessible concrete walls and floors, using a cold chisel and a hammer.
During a recent refresher training session in Anaheim, an instructor noted that concrete in the middle of a wall or floor may be different than concrete on the surface. He (or someone) suggested coring through each slab or wall to get a better representation of the material. We performed a few of these cores, but I didn’t like it. It seemed overly burdensome and expensive for the client. l So I wrote directly to the SCAQMD, requesting clarification. My letter and their response are shown below:
From: Duane Behrens [mailto:
Sent: Tuesday, June 18, 2019 1:23 PM
To: Christopher Ravenstein <
Cc: Ellis Professional Staff <
Subject: Sampling Concrete
Hi, Chris. Our understanding of Rule 1403 indicates that concrete is indeed a suspect ACM. In the past, we’ve used a cold chisel and hammer to knock off a chip from the concrete’s surface. Ryan in our office correctly notes that this procedure may only capture the top, non-aggregate portion (“cream”) of the concrete. So we’ve taken to coring concrete walls and floors to get samples that are more representative of the material.
Retaining and scheduling a coring contractor is, of course, quite a bit more expensive and time-consuming than just chipping off a piece from the surface with a cold chisel. So I’d really appreciate your input on the subject. Is coring truly necessary? Or would you accept results from surface samples collected the old way (hammer and cold chisel)? Let me know. Thank you.
ELLIS ENVIRONMENTAL MGMT INC
Duane Ellis Behrens, President
CAC #92-0226 CDPH #7914
Good Afternoon Duane,
I’ve discussed this with supervisors in Toxics. While we refer to materials as “homogeneous”, we are cognizant of the fact that those materials that are mixed and applied onsite aren’t ALWAYS uniform in their makeup throughout. For instance, stucco. Stucco sample results can vary widely. Another example is acoustic ceiling material. Results from acoustic sampling can vary significantly.
While it may be true that the concentration of asbestos fibers (if any) in the concrete may not be uniformly distributed through the cement matrix, we do not believe that the surface cement, or “cream”, would tend to have a wildly different concentration. There’s really no reason to think that it would, and we haven’t seen any data to suggest that it is.
It is our opinion that a sufficient number of representative surface samples of the concrete are adequate to characterize the material.
Christopher A. Ravenstein
South Coast Air Quality Management District
Everyone has the right to breathe clean air