Turbidity Monitoring: Addressing Gaps for Erosion and Sediment Control in Canada
Citation
Executive Summary
Construction activities can result in soil erosion and the transport of sediment beyond the limits of an active work area. Sediment generated from the exposure of erodible soils on construction sites can be carried by stormwater runoff and is ultimately released to watercourses, wetlands, important natural features, private property, and existing drainage infrastructure. This can then lead to the degradation or destruction of aquatic and terrestrial biota and associated habitats, the loss of structural integrity and functionality of watercourses and other natural features, flooding, and costly infrastructure maintenance.
To help prevent both short-term and long-term adverse impacts to the environment throughout the lifespan of a construction project, it is important that effective, industry-wide practices that foster the proper inspection and monitoring of erosion and sediment control (ESC) measures be developed. These practices, coupled with effective and dynamic ESC plans are critically important components of successful construction projects, and when implemented and properly maintained, can effectively minimize impacts to infrastructure and the environment.
The recently published CAN/CSA-W202, Erosion and Sediment Control Inspection and Monitoring is a first of its kind National Standard of Canada. While it goes a long way towards harmonizing a set of national requirements for inspecting and monitoring ESC measures, there exists an opportunity to provide further guidance on implementation. Specifically, while the standard provides turbidity monitoring performance targets, it does not instruct users as to how to conduct monitoring or how to set up ESC measures to meet the prescribed targets. As such, the objective of this research project was to help ESC stakeholders in Canada better understand what it takes to meet their turbidity monitoring targets in terms of ESC measure implementation and the use of various technologies available to monitor their project sites. Through a series of case studies (both literature-based and survey-based), this research demonstrates the challenges and successes experienced on past construction projects where turbidity monitoring was a requirement. In doing so, the report provides readers with context that will allow them to make informed decisions about their site management, ESC methods, and turbidity monitoring efforts.
Based on the results of the case studies, the most common challenges associated with turbidity and total suspended solids (TSS) monitoring were identified as equipment maintenance, accounting for natural variability in telemetry-based monitoring technologies, and meeting standard targets based on pre-development levels of turbidity and TSS in receiving watercourses. This report provides recommendations to improve ESC effectiveness and turbidity, and TSS monitoring protocols specifically to address such challenges. Turbidity and TSS monitoring successes were associated with using continuous data collection equipment, reprogramming telemetry-based systems to account for natural variability, as well as reducing the duration of turbidity and TSS exceedances.
This report also provides a description of “lessons learned” when applying various turbidity monitoring technologies across different scenarios. Based on issues commonly experienced on-site, recommendations to inform successful site management and turbidity and TSS monitoring, were provided. These recommendations included incorporating project phasing and considering weather constraints, identifying sediment sources and considering these locations in monitoring station setup, and maintaining open and effective communication during ESC projects.
Copyright
© 2020 Canadian Standards Association. All Rights Reserved.
Authors
- Josie Mielhausen, M.Sc., Geo Morphix Ltd.
- Paul Villard, Ph.D., P.Geo., CAN-CISEC, EP, CERP, Geo Morphix Ltd.
- Michael Lawson, C.E.T., CAN-CISEC, EP, Geo Morphix Ltd.
Project Advisory Panel
- David Green, R.T. Bio, R.B. Tech, CAN-CISEC, Peter Kiewit and Sons (ULC)
- Andy Ingriselli, Aquatech Dewatering
- Glenn MacMillan, C.E.T., Toronto and Region Conservation Authority
- Graham Tait, CPESC, CPSWQ, CAN-CISEC, The City of Calgary
- Dan Menard, P.Geo., QP, MBA, Groundwater Environmental Management Services
- Brian Zupancic, M.Sc., CSA Group (Project Manager)
- Jennifer Teague Ph.D., CSA Group
Acknowledgements
The authors would like to thank the survey participants for sharing their experiences with turbidity monitoring. Sharing both the successes and challenges of your work ultimately contributes to more successful ESC projects in the future. The authors also wish to thank Kori Archer (McElhanney) and Joanne Letkeman (BC Ministry of Transportation and Infrastructure) for their contributions to this work.
Disclaimer
This work has been produced by Geo Morphix Ltd. and is owned by Canadian Standards Association. It is designed to provide general information in regard to the subject matter covered. The views expressed in this publication are those of the authors and interviewees. Geo Morphix Ltd. and Canadian Standards Association are not responsible for any loss or damage which might occur as a result of your reliance or use of the content in this publication.
