Multiple Geosyntec practitioners will present at the virtual 36th Annual International Conference on Soils, Sediments, Water, and Energy on October 19-23, 2020.

The Annual Conference on Soils, Sediments, Water and Energy has become the preeminent national conference in this important environmental area. The conference attracts 600-800 attendees annually, including a wide variety of representation from state and federal agencies, military, industry (including railroad, petroleum, transportation, and utilities), environmental engineering, environmental consulting, and academia.

The Association for Environmental Health and Sciences Foundation, Inc. is a non-profit, member-supported, professional organization. Our purpose is to facilitate communication and foster cooperation among professionals concerned with the challenge of soil, sediment, and water assessment, clean-up, and protection.

Geosyntec Participation

Title: 3-D Modeling to Support Interim and Postconstruction Groundwater Management Decisions for a Large Remediation Project
Presenters: Dariusz Chlebica, PG (Geosyntec)
Coauthors: Denise Tripp, Sharon Lau, David Adilman, Danielle Thorson (Geosyntec), Laura Solano (Michael Van Valkenburgh Associates, Inc.), Meggen Janes (Waterfront Toronto)
Session: Session 02: Enhancing Remediation Outcomes through Planning and Assessment
Time: 3:30-4:00 PM EDT on October 19, 2020
Abstract:
Construction projects that have a need for hydraulic control during an excavation often require groundwater models to optimize aspects of the design and estimate future groundwater flow conditions during interim and post construction conditions. The presence of impacted groundwater in the vicinity of an excavation can further complicate the dewatering process by requiring water treatment that can significantly increase the cost of the project. Although a 2-dimensional seepage analysis can provide adequate groundwater inflow estimates in idealized settings, three-dimensional groundwater models are preferable in complex hydrogeologic settings with nearby surface water bodies, variable stratigraphy and complex geometries.

As part of the Port Lands Flood Protection and Enabling Infrastructure Project (PLFPEI) in Toronto, Ontario, a series of three-dimensional models were developed to support construction of a new river channel through an approximately two square mile former industrial area connecting the mouth of the Don River to Lake Ontario. A preconstruction model simulating existing conditions was developed with Site-specific and regional hydrogeologic data and Don River and Lake Ontario stage elevations and calibrated using groundwater levels measured in wells throughout the Site. An Interim construction model was developed to simulate the impacts of vertical cutoff walls and horizontal drain systems during construction while a post construction model was developed to incorporate final design elements including a horizontal barrier to isolate impacted groundwater, new river valley finish materials, and final re-development elements such as parks, roads, and buildings. The PLFPEI illustrates how groundwater models were used to evaluate optimal hydraulic cutoff wall tip elevations, estimate groundwater inflow volumes for dewatering purposes, inform future long-term post-construction monitoring through the use of predict advective contaminant flow paths and travel times, and assess potential for groundwater mounding outside the cutoff wall system during periods of high lake levels.

Title: Challenges and Benefits of using RT-qPRC to Analyze for the SARS-CoV-2 Virus in Environmental Samples
Presenter: Sam Williams, PG, CHG, CEM (Geosyntec)
Coauthor: Duane Graves (SiREM Labs)
Session: Session 01: COVID-19 Environmental Concerns
Time: 3:30-4:00 PM EDT on October 19, 2020
Abstract:
The global COVID-19 pandemic has affected all aspects of our communities, businesses and the economy. Using existing technology, scientists can support efforts to combat this viral outbreak while a vaccine is being developed. SARS-CoV-2 (aka novel coronavirus) is the virus that causes the COVID-19 disease. The coronavirus is spread from person to person as an aerosol and by contact with contaminated surfaces. A single sneeze can produce up to 40,000 droplets of saliva with each carrying up to 2,000,000 coronavirus particles. When you do the math, the total delivery approaches 100 billion particles in a single sneeze from an infected person.

Genetics laboratories have been using Reverse Transcriptase-quantitative Polymerase Chain Reaction (RT-qPCR) to analyze RNA for decades. Within the last year, this method has been modified to specifically analyze for the RNA of the novel coronavirus not only for clinical purposes but also for environmental samples. In efforts to return to work and stay safe while at work, the workplace is continually being disinfected. The CDC and EPA have developed guidelines which constitute the current but evolving standard of care for disinfection. The methods used for verifying that surfaces have been adequately disinfected range from “none” to “pH paper” to “adenosine triphosphate (ATP)” to the gold standard, “RT-qPCR”. RT-qPCR is the only method to definitively confirm that a surface has been adequately disinfected and that a disinfection contractor has effectively applied a disinfectant product.

It has also been determined that infected humans, whether symptomatic or asymptomatic, shed the novel coronavirus in their feces. Studies have shown that the novel coronavirus can remain detectable in wastewater for at least 48 hours and may be detected for longer than that. Recent efforts in Europe and the US have been able to successfully detect the novel coronavirus in waste water using RT-qPCR and use these data to track viral baselines in a community. When infection rates go up the viral loads go up. Most interesting is that increases in viral loads can be observed up to two weeks before infections are being reported in the community – because of asymptomatic and pre-symptomatic infected individuals who shed viruses prior to displaying clinical symptoms. Communities can use these data to issue stay at home orders, social distancing guidelines, business operating practices, mask usage directives, gathering restrictions, and other actions that are intended to stem the transmission of the virus. The effect of these measures can be monitored by the virus concentration in wastewater as well as epidemiological and clinical data.

Title: Remediation and Real-Time TCE Air Monitoring During Construction in a Densely Populated Urban-Residential Setting
Presenters: Dariusz Chlebica PG (Geosyntec)
Coauthors: Jessica Yeager, Zach Grosso (Geosyntec)
Session: Poster Session
Time: 3:00-6:00 PM EDT on October 20, 2020
Abstract::
Construction and remediation at brownfield sites in densely populated urban-residential areas requires diligence and specific considerations for surrounding receptors. The presence of chlorinated volatile organic compounds (CVOCs), specifically trichloroethene (TCE), in soil and groundwater at a metro Boston site presented unique challenges during soil excavation activities for an apartment complex. Subsurface investigations included pre-characterization soil sampling to develop a soil management plan and designate the final disposition of soils and installation of monitoring wells to monitor the TCE-impacts in groundwater. The soil data was used to evaluate the anticipated level of off-gassing during excavation of TCE-impacted soils. A ground-level garage was incorporated into the building design to mitigate vapor intrusion risks associated with the TCE-impacted media that remain in place. A comprehensive real-time air quality monitoring program was developed with regulatory input to monitor the wind direction, Total VOCs, and TCE concentrations along the perimeter of the site using a Photoionization Detector and a Frog 4000/5000 portable gas-chromatograph at 15-min increments. The plan included trigger concentrations and contingencies for additional samples to be collected immediately at the surrounding properties and agreements with residences and a middle school for indoor air sampling should the outdoor results exceed the residential imminent hazard level for TCE of 6 µg/m3 (1.1 ppbV). The monitoring was complicated by a trigger concentration set near the reporting level of the unit (5.37 µg/m3 [1 ppbV]). The factory-calibration of the unit, including retention time was checked several times a day using a custom formulated TCE gas at a concentration of 26.3 µg/m3 (4.9 ppbV). The project serves as an example of a successfully executed residential excavation with close receptors, significant regulatory involvement, and real-time monitoring. The construction activities have been completed and the site is currently on track for closure under the state regulatory program in early 2020.

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