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GeoInsighter Winter 1999 Newsletter

New VOC Analytical Technique

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If you have ever compared results obtained from field screening a soil sample for volatile organic compounds (VOCs) against laboratory results of a duplicate sample, you know that they are rarely similar. In fact, the disparities in results are typically several orders of magnitude, with the greatest differences noted in courser-grained soil samples. This is primarily due to the loss of volatiles during collection of the sample and in the laboratory when the sample is being prepared for analysis. Factors such as biodegradation and sample heterogeneity also play a role. The phenomena had its first financial impact on owners and operators of petroleum facilities, who experienced difficulty in obtaining payment from state reimbursement funds because laboratory results failed to confirm that the soil removed from their site was, in fact, dirty.

The United States Environmental Protection Agency (EPA) formally addressed the problem in August 1997 with the publication in the Federal Register of Method 5035, a new component of SW-846. Of greatest impact is the method's requirement to avoid loss of volatiles from the field to the laboratory. Although there are several techniques available to meet this requirement, field preservation using methanol is the most common and easiest to implement. 

Few states have formulated policies to ensure compliance with the EPA methodology. Massachusetts and New Hampshire share different views on implementing the rule change. On March 5, 1999, the Massachusetts Department of Environmental Protection (MADEP) published as Final Policy Preservation Techniques for VOC Soil Sample Analysis (WSC # 99-415) that requires all soil samples analyzed for VOCs to be collected in conformance with Method 5035. In most cases, this does not represent a significant change from the Volatile Petroleum Hydrocarbon sampling methodology that has been required in Massachusetts on petroleum-impacted sites since October 31, 1997. Soil samples collected in Massachusetts on or after March 15, 1999 for all VOC analyses, including Methods 8015A, 8021A, and 8260A, must conform to Method 5035 or the results will be categorically rejected by the MADEP.

The New Hampshire Department of Environmental Services (NHDES) laboratory is suggesting the use of methanol preservation as well. However, the NHDES has not published any guidance on the issue and still accepts VOC soil data obtained without using Method 5035.

Implementation of the method may add additional field and analytical costs to a project, but it is the inevitably higher VOC concentration detected in the soil that could significantly impact an environmental project's bottom line. It can be anticipated that more soil will require treatment or removal, or that more site specific risk characterizations (Method 3) will be necessary to demonstrate that conditions no longer pose a significant risk. 

Michael F. Dacey, L.S.P.
mfdacey@geoinc.com

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