Tuesday, June 24, 2008 : 3:40 p.m.

Use of an On-Site Mobile Laboratory to Guide the Expedited Investigation of an MTBE Impact to a Deep Public Water Supply: Data Uncertainty Associated with Field Analytics and Temporal Effect on Sampling

Donald A. Trego1, Roberto J. Peraza1 and Joseph E. Haas II, M.S., PE2, (1)Environmental Assessment and Remediations, (2)New York State Department of Environmental Conservation

MTBE contamination detected in the West Hempstead Water District Birch Street Well Field at a concentration of 154 micrograms per liter (μg/L) at depths of approximately 60 meters was defined utilizing an Expedited Site Characterization (ESC) methodology. The ESC entailed the dynamic installation of Multi-Level Nested Well Bundles (MLNWBs) by hollow stem auger techniques coupled with immediate sampling and field analysis. The field data consisted of temperature, dissolved oxygen, pH and ORP obtained via a multi-parameter meter equipped with a flow thru cell, as well as, MTBE and other volatile organic compounds (VOCs) obtained via an Agilent model 6890 Gas Chromatograph equipped with a 5973 Mass Selective detector (GC/MS). The need to utilize potable water during the installation of the MLNWBs to overcome hydrostatic pressure was identified as a possible source of data uncertainty. To assess the uncertainty stemming from the introduction of potable water into the aquifer, field data (which was utilized to guide the ESC) was correlated against sample duplicates analyzed by a fixed based certified laboratory.  This correlation was completed for both the immediate sampling event and a sampling event conducted two weeks after the installation of the MLNWBs.  A comparison of the on-site mobile laboratory results and the fixed based laboratory results indicates a direct linear relationship between the separate analyses. A comparison between the time delayed sampling and the initial sampling indicate that although the time delayed sampling results provided slightly greater resolution of the contaminant plume, the initial sampling results had strong correlation with the delayed sampling results and did not alter the conceptual site model. This analysis suggests that immediate sampling and analysis of traditionally installed MLNWBs can be used with confidence to expedite site characterization in similar settings.

Donald A. Trego, Environmental Assessment and Remediations Don graduated in 1993 from the Pennsylvania State University with a bachelors of science in Environmental Resource Management. He has over 14 years of experience in the groundwater remediation industry. Don has been involved in numerous research initiatives with the New York State Department of Environmental Conservation (NYSDEC), the United States Environmental Protection Agency (USEPA), and the United States Geological Survey (USGS). As project manager, Don was a co-recipient of the 2004 National Ground Water Association’s (NGWA) – Outstanding Groundwater Remediation Project award. He currently is the Vice president of a respected environmental consulting firm located on Long Island, NY.

Roberto J. Peraza, Environmental Assessment and Remediations Roberto is the lead technical director of the analytical services department of Environmental Assessment & Remediations. Roberto graduated with a Bachelors of Science in Chemistry with a double major in Philosophy from Boston College. He has 5 years of research and analytical chemistry experience and 2 years of laboratory management and operational experience.

Joseph E. Haas II, M.S., PE, New York State Department of Environmental Conservation Joe has 19 years experience working as a state regulator managing a remedial section. He holds both Engineering Geologist and Hydrogeologist specialty licenses. Joe has been involved in research with representatives of the United States Environmental Protection Agency. These research efforts have been credited as having made significant contributions to the understanding of the characteristics of MTBE in the sub-surface environment and having influenced the national debate on the use of MTBE in gasoline. The Office of Research and Development acknowledged his contributions, in 2002, in the form of an award for Exceptional Support to ORD.


2008 NGWA Conference on Eastern Regional Ground Water Issues