Stream 4B
ASSESSEMENT 
 
<< -  -  -  -  -  -  -  -  -  - >>
 
 
 Quick Links: 

<< -  -  -  -  -  -  -  -  -  - >>

Concentration-response Analysis in Aquatic Ecological Risk Assessment
Ryan Hill and Bryan Pyper
Azimuth Consulting Group Partnership

The objective of this presentation is to focus on approaches for determining whether observed ‘effects’ in aquatic ecological risk assessments can be attributed to site-related contaminants.

Abstract

Ecological risk assessments (ERA) for aquatic sites are typically based on several lines of evidence such as sediment chemistry, porewater chemistry, bioassays and benthic invertebrate surveys. Most practitioners plan ERA studies using control-impact designs that emphasize evaluation of the magnitude of exposure and effects relative to environmental quality guidelines, reference sites or lab controls. However, weight-of-evidence conclusions about risks should be based not only on magnitude but also on evidence for causality. Potential for causality can be evaluated to some extent by considering relationships among endpoints, particularly the relationships between exposure and effects endpoints. With this in mind, ERAs should be planned in a way that characterizes concentration gradients and thereby facilitates concentration-response analysis. This presentation will draw on data from several aquatic sites we have worked on, to illustrate the use of plots and quantitative models in evaluating concentration-response for various types of endpoints. 

<< -  -  -  -  -  -  -  -  -  - >>

Strategies for Assessing Ecological Risks at Foreshore/Aquatic Contaminated Sites 
Beth Power, Norm Healey, Patrick Allard
Azimuth Consulting Group Inc.

The objective of this presentation is to discuss the assessment of ecological risks in the transition zone from foreshore to aquatic environments at federal sites and the associated challenges. 

Abstract

This presentation will review strategies for assessing ecological risks at foreshore/aquatic sites in a manner that avoids common pitfalls. Frequently, remediation to numeric targets is not feasible for technical and/or cost reasons, so assessment of (residual) risks is necessary. Aquatic ecological risk assessments can involve more time and funding than is initially estimated. Challenges to risk assessment of foreshore/aquatic sites include: converting understanding of groundwater quality into exposure conditions for aquatic receptors; apportioning “cause” of effects to chemical vs. physical stressors; analysis of ecological effects in a spatial context; and, translating risk assessment findings into risk management. For each of these challenges, strategies and examples will be presented in the context of Federal sites. The target audiences for this presentation are project managers and decision-makers who manage foreshore and aquatic sites. 

 
<< -  -  -  -  -  -  -  -  -  - >> 

Accurate Measurement of Core Recovery Using an Enhanced Vibracore Technology
Doug McMillan1, Dave Munday2, Tom Wright2, Dave Kettlewell1, Scott Irwin3
1SNC-Lavalin Inc.
2Coastline Technologies Inc.
3Defence Construction Canada

The objective of this presentation is to provide an introduction to new vibracoring technology developed by Coastline Technologies Inc. that allows for improved accuracy in core recovery measurements and data confidence.

Abstract

The accurate characterization and assessment of marine sediment is an important step for environmental characterization and remediation of marine based contaminated sites. Investigation of marine sediments is commonly completed using a vibracore equipped sampling vessel capable of coring marine sediments. Extracted cores provide data that is related to in-situ sediment depths. The data collected from sediment investigations is integral to delineate sediment contamination and to estimate contaminated sediment volumes for potential dredging remediation.

Typically, vibracore sampling vessels are equipped with GIS navigation systems and depth sounders to provide accurate measurements of sample coordinates and water depth (to mudline). Other measurements and observations are recorded during sediment coring and include drive penetration, headspace measurement, and core recovery. These measurements allow the geoscientist to determine the recovery percentage which is then used to apply a correction factor to the recovered sediment core and determine sampling intervals. Uncertainty with respect to the measurements of core recovery and core corrections can have a large impact on the accuracy of sample intervals and, therefore, estimated remediation volumes. Error and uncertainty in remediation volumes can lead to significant increases in remediation costs.

In recognition of this issue, Coastline Technologies Inc. (Coastline) has developed, with the support of the National Research Council’s (NRC) Industrial Research Assistance Program (IRAP), a new technology to provide measurements of core tube penetration and core recovery. This new technology offers digital data measurements in real time that can be used to improve the efficiency of Coastline’s coring systems. We anticipate that these results, when applied to the selection of sampling intervals, will greatly increase the accuracy and precision of sediment core measurements and sampling intervals and, therefore, the accuracy and precision of all data that are derived from those measurements.

The new measurement system allows the operator to zero the measurement system immediately prior to taking the sample. The core tube penetration measurement is a proxy for depth of sediment. A second measurement system records the level of the sediment as it enters the core tube. Real time measurement in 1.0 cm increments are recorded and compared to provide percent core recovery for each 1.0 cm increment. The operator can adjust vibracore parameters to optimize core recovery. On extraction and retrieval, the measurement system detects any changes (core catcher inversion, washout, etc.) that might affect the data acquired from the core prior to sampling. The results for each core sample are transferred to the core sampling team so that the geoscientists know how the core relates to in-situ sediment depths for each core sampled.

SNC-Lavalin and Coastline will employ this technology in field trials between January and March 2017 to test technology and to compare the data and results to previously used techniques. SNC-Lavalin plans to complete data analysis and comparisons using statistical techniques to demonstrate improvements to sample confidence, remediation volume estimates, and investigation costs. 

Questions en

fb icon   Twitter icon   linkedIn icon