WP16 Sediment Quality Assessment
Wednesday, 16 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(LEI-1117-813969) Achieving closure of a sediment area at a New Jersey site: A sediment triad study.

Leigh, K¹, Barber, T¹, Fuchsman, P¹, Zahradnik, A², Demarest, E³, ¹ ENVIRON International Corporation, Burton, Ohio, USA² ARCADIS, Melville, New York, USA³ New Jersey Department of Environmental Protection, Trenton, New Jersey, USA

ABSTRACT- Multiple lines of evidence were used to determine whether site-related constituents adversely impacted sediment quality in a small stream adjacent to a former electronic manufacturing site in Hanover Township, New Jersey. A sediment triad was conducted consistent with New Jersey Department of Environmental Protection (NJDEP) regulations and guidance. The approach consisted of the evaluation of co-located benthic community surveys, toxicity tests, and specialized sediment chemistry data for both on-site and upstream reference areas. Each of these lines of evidence was integrated using a weight-of-evidence approach to draw conclusions about the relationship between chemicals and biological community quality. The purpose of the study was to demonstrate whether metals detected in sediment above background and/or NJDEP screening levels adversely impacted the environment. Chronic whole-sediment toxicity tests, including a 28-day exposure for Hyalella azteca and a life cycle test (approximately 60-day exposure) for Chironomus tentans, were conducted on composite sediment samples, co-located with the samples collected for sediment chemistry. The bioavailability and potential toxicity of metals in sediment was evaluated using acid volatile sulfide (AVS) and simultaneously extracted metals (SEM) and the analysis of dissolved metals in sediment porewater. The weight-of-evidence assessment determined that although metals were present in sediment at concentrations above the NJDEP screening values, the sediment was not toxic, and the resident benthic invertebrate community was not impaired. Thus, the metals were not sufficiently bioavailable to cause ecological harm. As a result of this investigation, the NJDEP issued a No Further Action determination for this area of the site.

Key words: sediment triad, metals, weight-of-evidence, AVS/SEM