March 6, 2020

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Geosyntec to Present at the 30th Annual International Conference on Soil, Water, Energy, and Air

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.

Geosyntec professionals will be presenting five presentations, two workshops, and chairing one session at this event. Also, Sam Williams, P.G., CHG (California) served on the Scientific Advisory Board (SAB).

The AEHS Foundation attributes the success of this conference, in large part, to a very dedicated and hardworking SAB. The SAB evaluates abstract submissions, recommends invited papers and presenters, advises with regard to session topics, and serves as conference ambassadors. The SAB is crucial to the conference development. Care is taken to create a board that represents philosophical, scientific, regulatory, and geographical balance.

March 2020 will mark the thirtieth annual gathering of environmental professionals to the Conference on Soil, Water, Energy, and Air. For the past twenty-nine years, this annual conference has helped to bring the environmental science community closer together by providing a forum to facilitate the exchange of information of technological advances, new scientific achievements, and the effectiveness of standing environmental regulation programs. The International Conference on Soil, Water, Energy, and Air and AEHS Foundation Semi-Annual Meeting offers attendees an opportunity to exchange findings, ideas, and recommendations in a professional setting. The strong and diverse technical program is customized each year to meet the changing needs of the environmental field.

Founded in 1990 as the Association for Environmental Health of Soils, AEHS has provided an international forum for over 600 members, industry experts, researchers, and governmental organizations to exchange information and advance awareness of environmental issues. The AEHS network spans professional disciplines from across the U.S. and abroad including biology, chemistry, geology and hydrogeology, engineering, and regulatory science.

Geosyntec Participation


Title: A Theoretical Assessment of PFAS VI Potential and Implications
Presenter: Travis Kline, MEM (Washington, D.C.)
Time/Location: 3:30p.m. – 4:00p.m., March 17, 2020, Great Room 6
Geosyntec conducted a preliminary evaluation of PFAS compound volatility by calculating theoretical maximum vapor concentrations and theoretical dimensionless Henry"s Law Constants from reported vapor pressures and aqueous solubilities for several classes of PFAS compounds.

The compounds exhibit a wide range of vapor pressures (2E-04 to 1E+03 Pa), aqueous solubilities (1E-05 to 1E+04 g/L) and, consequently, a wide range of calculated vapor concentrations (5 to 2E+8 μg/m3) and theoretical dimensionless Henry"s Law Constants (1E-09 to greater than 1). The vapor pressure indicates the volatility of the compounds from pure-phase liquid or solid phase and the Henry"s Law Constants indicate the volatility of the compounds from the aqueous phase. The upper end of the range of calculated PFAS Henry"s Law Constants spans the range of most volatile organic compounds of concern for the vapor intrusion pathway.
To identify compounds most likely to yield air concentrations that may pose an inhalation concern, Geosyntec compared the theoretical maximum vapor concentrations to estimated levels of potential concern (LOPC) calculated using available USEPA, ATSDR, and state-promulgated toxicological criteria. Consideration of absorption efficiency, distribution in the body, metabolism, and potential for portal-of-entry effects are discussed to support route-to-route extrapolation in derivation of provisional inhalation toxicity criteria to advance these comparisons, predicated on default USEPA-promulgated intake parameter values.

Results suggest that several PFAS compounds may have the capacity to be present in ambient/indoor air at levels that may result in doses above provisional LOPCs. A preliminary review of published literature on PFAS compounds measured in indoor air found that several of the compounds with the highest potential to exceed Geosyntec"s estimated LOPCs were frequently reported as detected in indoor air. These results may be useful for targeting which PFAS compounds to focus on when investigating potential inhalation risks from exposures due to environmental releases of PFAS compounds.

Title: Lessons Learned from Radon at a Chlorinated Vapor Intrusion Research House
Presenter: Chase Holton, Ph.D., P.E. (Colorado)
Time/Location: 11:30a.m. – 12:00p.m., March 18, 2020, Gallery
Indoor air and subslab soil gas volatile organic compound (VOC) samples are recognized as important lines of evidences for vapor intrusion (VI) investigations. These samples can be confounded by temporal and spatial variability, as well as indoor and ambient VOC sources. Short-term sampling (e.g., 8- to 24-hour for indoor air samples) under natural conditions continue to be the most common sampling approach for assessing the VI pathway. Radon is a naturally occurring radioactive gas found in soil that can be used as a low-cost indicator and tracer of VOC vapors, since it may migrate along the same pathway(s) as VOCs for some sites and indoor sources are often considered negligible. More recently, radon has been proposed as a potential line of evidence for guiding VOC sampling time and location.

This study provides an evaluation of radon as an indicator and tracer for improving confidence in decision making using short-term indoor air and subslab soil gas sampling results. Concurrent real-time indoor air VOC and radon concentration data, along with monthly multi-depth soil gas surveys, were collected over a two-year period at a VI research house. Preliminary analyses show that indoor air temporal variations of TCE and radon follow similar long-term (i.e., seasonal) and short-term patterns; however, differences in subsurface distribution and soil gas-to-indoor air attenuation factors related to source characteristics and preferential VOC vapor transport have also been observed. The results of this study highlight the utility of radon as an indicator and tracer in VI investigations, as well as the limitations of radon as a surrogate for VOC measurements.

Session Title: PFAS Assessment and Remediation
Session Chair: Sam Williams, P.G., CHG (California)
Time/Location: 1:30p.m. – 3:00p.m., March 18, 2020, Great Room 6

Title: Fast-Forwarding Redevelopment of Brownfields Using Barriers Systems
Presenter: Rebecca Oliver, P.E. (California)
Time/Location: 3:00p.m. – 6:00p.m., March 18, 2020, West Foyer
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.

Title: EPA's Revised Cost-Benefit Policy: What Does It Really Mean at Sediment Sites?
Presenter: Scott Rowlands, P.G., CEG, CHG (California)
Time/Location: 8:30a.m. – 9:00a.m., March 17, 2020, Shutters East 1
Summary: EPA Administrator Wheeler issued a May 2019 memorandum ordering that the Agency increase "consistency and transparency" in considering costs and benefits of environmental regulation. Administrator Wheeler directed various Assistant Administrators for Air, Chemical Safety, the Office of Land and Emergency Management (OLEM), and Water to proceed with rulemaking as to specific media, presumably including air, water and Superfund programs. This presentation will explore the revised regulatory policy and then explore its potential impacts in a major sediment Superfund cleanup at Portland Harbor.

Background: Criticism of EPA"s analysis of costs and benefits is not new. In 2015, the Supreme Court held that EPA"s failure to consider the costs of its new rule regulating air emissions constituted an abuse of the agency"s authority. The Supreme Court majority found that the statutory command that an agency regulate hazardous air pollutants as "necessary and reasonable" must include a consideration of costs in the case Michigan v. EPA, 135 S. Ct. 2699 (2015). In 2018, then EPA Administrator Pruitt announced an initiative via a notice of proposed rulemaking to review EPA"s overall approach to cost-benefit analysis. The current Administrator, Wheeler, has now concluded in his May 2019 memorandum that EPA's cost-benefit analysis requires a "media-specific approach, taking into account the variety of statutory programs."

Case study: The failure of EPA to apply a rigorous cost-benefit analysis to major sediment sites in the Superfund context. Panel members will consider the application of this general EPA policy in the context of the Portland Harbor Superfund Site. The Portland Harbor site is a major sediments clean-up program whose remedial costs are estimated to be some $1 billion (that"s with a "B") per EPA"s Record of Decision. Some PRPs estimate the realistic costs to be in excess of $2 billion, and are pursuing alternative approaches that reduce cost and construction duration but still achieve EPA"s goals of protecting human health and the environment. Will EPA now revisit this and other "mega-sites" (over $50 million dollars in cleanup) under its new policy? What can scientists do to evaluate whether Agency cleanups truly balance realistic costs with actual benefits?

Title: Impacts of Urban Stormwater-Associated Polycyclic Aromatic Hydrocarbons on Receiving Sediment
Presenter: Megan Otto, P.E., QSP/QSD (California)
Time/Location: 11:00a.m. – 11:30a.m., March 17, 2020, Shutters West 1
Stormwater runoff from an urban environment is recognized as a major source of particle-associated polycyclic aromatic hydrocarbons (PAHs) whose endpoint is often the sediment of a receiving water body. Stormwater assessment has been traditionally centered on loads instead of impacts and that can lead to misevaluating the risk associated with runoff discharges. The objective of this study was to characterize storm runoff solids from a mixed-use urban watershed and determine the physical, chemical and biological effects they incur on receiving sediment.

The experimental approach involved a 2-year sampling plan (2015-2017) in Paleta creek at Naval Base San Diego (NBSD) utilizing a variety of sampling approaches including intensive sampling of individual storms with size-fractionation, water and sediment collection before and after the winter storm season and settling traps collecting depositing sediments throughout the storm season. Pore water sampling and both in-situ and ex-situ bioassays with bent-nose clams (Macoma Nasuta) were employed to determine the response of the receiving benthic ecosystem.

Size fractionated stormwater loads combined with settling trap solids analysis were identified as the most effective tools to assess sources and sediment contamination. Analysis showed that PAHs in stormwater are associated with coarser, organic-carbon rich particles that settle close to the creek discharge point. Parent and alkylated PAH ratios allowed stormwater from this watershed to be distinguished from sediments settling in areas away from the stormwater discharges and confirmed that the physicochemical effects of runoff are localized in the near-field. The bioaccumulation studies indicated that solids-associated PAHs in stormwater runoff have limited bioavailability that is significantly lower than what sediment PAH concentrations would predict. However, bioaccumulation was more closely predicted by pore water concentration measurements indicating that pore water passive sampling can be a relatively inexpensive surrogate for assessing PAH uptake of benthic ecosystems.


Title: Workshop 3, California"s Environmental Challenges: What Do We Do with Large Operating Facilities
Chair: Ravi Arulanantham, Ph.D. (California)
Time/Location: 1:00p.m. – 5:00p.m., March 16, 2020, Shutters West 1
Description: California has hundreds of large facilities that have been in operation for many decades (refineries, bulk terminals, tank farms, foundries, factories etc.) which are vital for the state"s continuing economy. Most of these are operating properties that contain significant amounts of persistent contaminants and have soil/groundwater impacts on-site and off-site above clean up levels. These facilities are typically in urban areas and are integral to the economic engines of the community and State. Despite years of characterization and remediation, contaminants remain above levels needed for closure. The technical and economic means to restore these sites may not exist. However, for many of these sites, there may be little or no imminent risk to humans or the environment. How to clean and continue to manage these sites in a manner that does not pose a threat to current and future public health, environment and water resources presents a real challenge into the future. This workshop will explore the risks these sites pose, the technical and economic feasibility of cleaning or reducing mass at these sites, the time frame to reach acceptable levels, the greenhouse gas emissions to reach such levels, existing regulatory frameworks, and finally balancing all the above interconnected factors and getting community acceptance. Panel members will focus on their experiences in answering the challenges and some approaches to continue managing these operating sites in California.

Title: Workshop 5, Why You Should Monitor Indoor Radon, Differential Temperature, and Pressure During Chlorinated Vapor Intrusion Assessments
Time/Location: 8:30a.m. – 5:00p.m., March 17, 2020, Gallery
Presenter: Chase Holton, Ph.D., P.E. (Colorado)
Description: While chlorinated vapor intrusion (CVI) is a complex and challenging-to-assess phenomenon largely due the apparently endless number of hard-to-identify, measure, and predict factors influencing the resulting variable indoor air concentrations; the in-depth study of a few readily-measurable/available Indicators and Tracers (I&T) has shown some impressive correlations with indoor CVOC concentrations due to CVI in the buildings studied to-date. Documentation of I&T measurements can significantly increase the quantitative confidence in the probability of measuring the exposure levels of most concern (e.g., RME or 95UCL) to that well above the random probability of typical individual sample efforts (~5%). Foremost among the I&T metrics is radon (Rn) which is a wide-spread naturally-occurring tracer of soil gas intrusion, mixing and retention in indoor air. The evidence and conceptual understanding indicates that the indoor concentration of Rn incorporates the effects of indicators such as temperature (a potential CVI driver), as well as pressure changes (including barometric, wind speed, and building operations) and integrates their effects across both space and time. More specifically indoor Rn levels integrates their actual effects on soil gas intrusion and indoor air concentrations, in the specific building and under the conditions being investigated. While outdoor temperatures and pressures are readily available from nearby weather station records, the changes in indoor levels of radon, temperature and pressure can be measured "continuously" with relatively inexpensive meters. This workshop will review new evidence for I&T that have shown correlations with indoor CVOC concentrations in data-rich studies of many buildings (including those with complex preferential pathways) and report the evidence from new building types and climate zones. Presentations will include the results of a study of the "antecedent" I&T-levels leading up to indoor CVOC concentrations above the 95th percentile for these buildings, as well as an introduction to technology for automated I&T "triggered-sampling" methods and discussions on selecting I&T "trigger-rules" for automated sampling. The workshop will also present and discuss I&T "Fact Sheets" to assist regulators (& other stakeholders) collecting and/or reviewing I&T evidence supporting CVI Investigations. Additionally, there will be a report on the use of I&T to address spatial variability (i.e., to prioritize among buildings over the source area). Finally, the workshop will hold a panel/open discussion further exploring the conclusions of our previous workshop, with the question: Does the I&T evidence we have now support a general recommendation to: "Document the indoor radon, differential temperature and pressure levels at least at the time of CVOC sampling, and surrounding baseline periods for comparison, to allow and improve future understanding and interpretations of the buildings" intrusion levels at the time of CVOC sampling?"

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