Identifying and Controlling Sources of Ultra-Trace Metals in Control Blanks and Ensuring High-Quality Data for Sensitive Environmental Risk-Based Decisions

Oral Presentation

Prepared by L. Dupes1, M. Mc Anulty2, R. Vitale1, A. Reed1
1 - Environmental Standards, Inc., 1140 Valley Forge Road, P.O. Box 810, Valley Forge, Pennsylvania, 19482, United States
2 - BP Exploration (Alaska), Inc., 900 E. Benson Blvd., Anchorage, Alaska, 99519, United States


Contact Information: ldupes@envstd.com; 610-935-5577 ext 416


ABSTRACT

The control of blank contamination is a necessary requirement when evaluating the qualitative and quantitative accuracy of analytical results for decision-making purposes of site delineation, toxicological evaluations, and site remediation. This control is essential to differentiate actual site concentrations from potential sources of introduced field or analytical contamination, especially during development of background site metals conditions and cleanup criteria.

Trace-level concentrations of total and dissolved metals were observed in several equipment rinsate blank samples collected at multiple sites during the field sample collection seasons of 2014 through 2016. The detection of total and dissolved metals in these field quality control (QC) samples resulted in qualification of both total and dissolved sample results, which raised questions regarding the presence or absence of low-level site contamination. Although equipment rinsate blank samples do not have specific contamination acceptance criteria due to the field collection process, the purpose of equipment rinsate blanks is to verify that contamination was not introduced during the sample collection process or by sampling equipment.

The purpose of the investigation and identification was to determine potential sources of metals contamination in equipment rinsate blanks that could be identified, reduced, or eliminated. Multiple avenues of potential contamination were investigated including a study of sample tubing, peristaltic pumps and in-line filters; field observation of equipment blank collection processes; initial and post water-quality monitoring; sample bottle cleanliness; and storage of deionized water for use in collection of the equipment rinsate blanks. This presentation will provide details of the investigation process and results after implementation of several important corrective actions.