Implementation of the Cleanup Regulation <continued> The first, and most widely misunderstood issue, is composite sampling. Appendix A of the regulation includes a decision level procedure for composite samples that must be used to determine if one or more of the individual samples that make up the composite exceed the cleanup level. This procedure requires that the laboratory result, reported in ug/100 cm2, be compared to the cleanup level (0.5 ug/100 cm2) divided by the number of individual samples that made up the composite sample. This means that the clearance level for composite samples will be a number lower than 0.5 ug/100 cm2. For example, the clearance level for a composite sample made up of four individual samples would be 0.125 ug/100 cm2. Another clarification regarding composite sampling involves the sampling area. A composite sample can be made up of no greater than five individual (discrete) samples. The individual samples that make up a composite sample must be collected in accordance with the requirements for collecting discrete samples. For example, each discrete sample must be of an area of at least 100 cm2, or a multiple of 100 cm2. In addition, each discrete sample that makes up a composite must be collected from a discrete area, on a separate wipe. In other words, a four-point composite sample must be made up of samples from four discrete areas, and collected on four separate wipes. This may sound intuitive to many, but it is surprising how often this is misunderstood and misapplied. And lastly, as stated in the regulation, composite sampling may only be conducted in situations where contamination is expected to be relatively evenly dispersed throughout a given area. Composite sampling would not be appropriate in situations where known or suspected hot spots (such as cooking areas) may be encountered. There have also been questions regarding the number of preliminary and clearance samples that are required. In the case of preliminary sampling, any indication of contamination can be used in lieu of sampling. Therefore, if an entire structure is assumed to be contaminated, no preliminary samples are required. Conversely, the absence of contamination must be demonstrated through sampling in compliance with the regulation. Even if preliminary sampling is not specifically required, it may still be beneficial to aid in understanding contaminant concentration and distribution for the purpose of planning cleanup and clearance sampling. The requirements for clearance sampling include a minimum amount of area to be sampled, as well as a minimum number of discrete samples. For any structure of no greater than 1,500 ft2, where a meth lab has been identified, at least 1,000 cm2 of total surface area must be sampled. At least three discrete samples must be collected. The remaining required sampling area may be sampled using either discrete or composite samples, but a minimum of five samples must be collected (a composite sample is considered to be one sample). An additional 100 cm2 must be sampled for each additional 500 ft2 of structural floor space. If the structure is made up of more than one functional space, at least 500 cm2 of surface must be sampled for each functional space. Therefore, the required clearance sampling for a 2,000 ft2 structure with two functional spaces would include a total of 1,100 cm2, with at least 500 cm2 sampled in each of the functional spaces. As stated previously, there must be at least five samples collected, including a minimum of three discrete samples.
Adequate and appropriate
collection of clearance samples is crucial to ensuring compliance with the
regulations and establishment of the liability shield afforded under
Section 25-18.5-103(2), C.R.S. It is vital that the sampling requirements
in the regulations be understood and followed. Failure to do so puts both
the property owner and the consultant at risk. |