Fast-Forwarding Redevelopment of Brownfields Using Barriers Systems
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Brownfield development is occurring on sites where volatile organic compound (VOC) soil vapor concentrations exceed the accepted USEPA Regional Screening Levels (RSL"s) for unmitigated construction.

It is common for developers to install "proactive" -- i.e. voluntary -- soil vapor intrusion (SVI) mitigation systems without agency review and/or concurrence, based upon recommendations of project environmental professionals. These systems are normally passive, including soil vapor venting, barrier membrane, and perhaps subslab monitoring probes. Systems can also be made active by adding fans.

Regulatory agency concurrence with the design strategy lends itself to greater stakeholder trust; however, limited guidelines for VOC SVI mitigation system design and monitoring is available to assist regulators in review and approval of systems. In related SVI fields, such as radon and methane, the mitigation standards are mature. Government review and approval is routine; however, the mitigation strategies for these constituents may not be appropriate for VOCs due to different preferential intrusion pathways and low allowable indoor air concentrations of many VOCs.

Guidelines for determining and ensuring the effectiveness of VOC SVI mitigation systems need further thought. It is difficult for regulatory agencies to "approve" VOC mitigation approaches as standards for approval remain variable nationwide. Data from existing proactive and required VOC SVI mitigation systems may be utilized to develop routine approval standards for regulatory agencies.

This session will focus on aspects of SVI mitigation system design (vent, barrier, and monitoring), specification, construction, testing, performance, contingency plans, and oversight. Additionally, critical elements of regulatory review, approval, and performance standards will be presented. Laboratory and site-specific performance data for various membranes and systems will be discussed as well as the successes and pitfalls of construction. The overarching goal of the session will be presenting and discussing the proposed performance standards for SVI mitigation systems.

Publication Summary

  • Geosyntec Authors: Rebecca Oliver
  • All Authors: Rebecca Oliver
  • Title: The Association for Environmental Health and Sciences (AEHS) Foundations' 30th Annual International Conference on Soil, Water, Energy, and Air
  • Event or Publication: Event
  • Practice Areas: Brownfield Redevelopment Planning and Design
  • Citation: Geosyntec practitioners will present at the Association for Environmental Health and Sciences (AEHS) Foundations' 30th Annual International Conference on Soil, Water, Energy, and Air on March 16-19, 2020. The conference will be held at the DoubleTree Mission Valley in San Diego, California.
  • Date: March 16-19, 2020
  • Location: San Diego, California
  • Publication Type: Platform Presentation