Grantee Research Project Results

Final Report: Self-calibrating Air Toxics Monitor

EPA Contract Number: 68HERC23C0016
Title: Self-calibrating Air Toxics Monitor
Investigators: Tolley, William
Small Business: Seacoast Science, Inc.
EPA Contact: Richards, April
Phase: I
Project Period: December 1, 2022 through May 31, 2023
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) Phase I (2023) RFA Text |  Recipients Lists
Research Category: SBIR - Water , SBIR - Homeland Security , SBIR - Sustainability , SBIR - Air and Climate

Description:

Seacoast has assembled and tested an automated analyzer, designated the SeaPort Self-calibrating Environmental Analyzer (SEA), to monitor indoor air quality (IAQ) in spaces suspected of containing air toxics.  These toxic vapors typically emanate from contaminated soil or groundwater such as Superfund sites.  This SEA is intended to provide analytical data more frequently than is currently possible using manual sample collection methods.  The analyzer is sufficiently compact and transportable so as to be installed directly in the area of suspected contamination, and operated without further operator intervention for days to months.  It can provide data at substantially lower costs by automating the sample collection and analysis steps.  This analyzer is compact, autonomous, and cost-competitive tailored specifically for chlorocarbons, carcinogens commonly found at Superfund and brownfield sites. The analyzer uses thermal desorption (TD) and gas chromatography (GC) for identification and quantification of air toxics present at sub-ppb levels.  This analyzer combines thermal desorption toxics collection, Seacoast's oven-less GC to speciate toxics, and photoionization for sensitive detection.  Additionally, the SEA is designed to re-calibrate its sensor output without human intervention to provide quality checks on the data during operation.  The ultimate goal is an autonomous analyzer to (1) repeatedly collect and analyze air in its immediate environment, (2) provide reliable data, wirelessly, to a network for environmental site managers to use in plume tracking models, and (3) reduce per-sample costs by cycling, unattended, between sample collection, analysis, and calibration, over a period of days to months.

Summary/Accomplishments (Outputs/Outcomes):

Seacoast assembled a SEA prototype and tested its operation in analyses of benzene, TCE and PCE vapors.  We have demonstrated the automated operation of the prototype SEA in laboratory testing.  In its current configuration, we have calculated a limit of detection as 2 ppt for PCE using this analyzer, well below our Phase I goal of 1 ppb.  We demonstrated isolation of benzene, TCE and PCE from potential interferents such as acetone (nail polish remover).  Lastly, we were able to demonstrate reproducibility within an average 0f 15%.  We benchmarked performance of the SEA against Seacoast Mini-GC.

Conclusions:

Seacoast believes that we have adequately demonstrated the concepts of our original proposal.  We demonstrated sorption and desorption of vapor compounds typical of vapor intrusion conditions using the TD tube.  We achieved simultaneous sampling of analyte.  We successfully delivered the vapor sample eluted during heating of the TD tubes to the gas chromatograph for chemical analysis.  Based on the analytical results, we calculate a limit of detection as 2 ppt for PCE using this analyzer.

In the U.S., there are over 450,000 brownfields^1,2 and over 1300 Superfund sites - sites polluted by hazardous chemicals that contribute to contamination of watersheds, aquifers, and municipal water systems.  In 1993, Chicago had an estimated 2000 brownfields.  Examples include sites formerly occupied by dry cleaners (chlorinated solvents), industrial facilities (solvents), and gas stations (leaky fuel storage tanks).  Many residual chemicals at these sites are considered carcinogens.¹  Vapors from residual chemicals may seep into the groundwater, which transports them to neighboring homes and schools.^2,3 Despite the likelihood of contamination that these sites pose to drinking water, Federal requirements are that municipal (drinking water) reservoirs are monitored only once every 3 months for TCE.⁴  Residents living near urban brownfield sites predominantly are poor, young, and renters.^5,6 There currently are few systematic studies to learn how many people might be affected by such contaminants.  It is estimated that returning these lands to beneficial use would increase tax revenues by $205M - $500M, add jobs, and reduce urban sprawl, but public concern regarding health risks from contaminants greatly impedes use of the sites.  The proposed monitor could provide the data on an on-going basis to assure the public that hazards have been remediated OR demonstrate to public health officials that hazards remain.

Seacoast obtained a Commercialization Readiness Assessment Report from Foresight Science & Technology under a TABA agreement exploring the potential market for the air toxics monitor. Further, Seacoast is consulting with Lloyd "Bo" Stewart, of Praxis Environmental Tech, Inc., to support Phase 2 field testing at customer sites when the Phase 2 field-ready version of the Analyzer is available.

References:

[1] US EPA website on brownfields, "Environmental Contaminants Often Found at Brownfield Sites," accessed 12/13/2021.

[2] Groundwater and Soil Cleanup: Improving Management of Persistent Contaminants, Commission on Geosciences, Environment and Resources (CGER), National Research Council, National Academy Press, Washington, D.C., 1999.US EPA National Priorities List: www.epa.gov/superfund/superfund-national-priorities-list-npl (accessed 7/2022)

[3] T. Illangasekare, Vapor Intrusion from Entrapped NAPL Sources and Groundwater Plumes: Process Understanding and Improved Modeling Tools for Pathway Assessment," SERDP, ER-1687 Fact Sheet.

[4] "Drinking Water Requirements for States and Public Water Systems," EPA 816-F-04-010 "EPA Standardized Monitoring Framework: A Quick Reference Guide."

[5] D. Lepore, "Determinants of the Number of Brownfields: An Analysis of U.S. Cities" 2005, Senior thesis in Economics.

[6] "Recycling America's Land: A National Report on Brownfields Redevelopment (1993 -2010)", United States Conference of Mayors, November 2010, Volume IX.