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Ground Water

Title:		Measurement of Natural Losses of LNAPL Using CO(2) Traps
Author(s):		McCoy K; Zimbron J; Sale T; Lyverse M;
Address:		"Department of Civil and Environmental Engineering, Colorado State University, 1320 Campus Delivery, Fort Collins, CO 80523-1320. Chevron Energy Technology Company, Site Assessment & Remediation Team, 6001 Bollinger Canyon Road, Bldg C1206, San Ramon, CA 94583-2324"
Journal Title:		Ground Water
Year:		2015
Volume:		20140718
Issue:		4
Page Number:		658 - 667
DOI:		10.1111/gwat.12240
ISSN/ISBN:		1745-6584 (Electronic) 0017-467X (Linking)
Abstract:		"Efflux of CO2 above releases of petroleum light nonaqueous phase liquids (LNAPLs) has emerged as a critical parameter for resolving natural losses of LNAPLs and managing LNAPL sites. Current approaches for resolving CO2 efflux include gradient, flux chamber, and mass balance methods. Herein a new method for measuring CO2 efflux above LNAPL bodies, referred to as CO2 traps, is introduced. CO2 traps involve an upper and a lower solid phase sorbent elements that convert CO2 gas into solid phase carbonates. The sorbent is placed in an open vertical section of 10 cm ID polyvinyl chloride (PVC) pipe located at grade. The lower sorbent element captures CO2 released from the subsurface via diffusion and advection. The upper sorbent element prevents atmospheric CO2 from reaching the lower sorbent element. CO2 traps provide integral measurement of CO2 efflux based over the period of deployment, typically 2 to 4 weeks. Favorable attributes of CO2 traps include simplicity, generation of integral (time averaged) measurement, and a simple means of capturing CO2 for carbon isotope analysis. Results from open and closed laboratory experiments indicate that CO2 traps quantitatively capture CO2 . Results from the deployment of 23 CO2 traps at a former refinery indicate natural loss rates of LNAPL (measured in the fall, likely concurrent with high soil temperatures and consequently high degradation rates) ranging from 13,400 to 130,000 liters per hectare per year (L/Ha/year). A set of field triplicates indicates a coefficient of variation of 18% (resulting from local spatial variations and issues with measurement accuracy)"
Keywords:		Air Pollutants/*analysis Carbon Dioxide/*analysis Environmental Monitoring/*instrumentation *Petroleum Soil Pollutants/*analysis;
Notes:		"MedlineMcCoy, Kevin Zimbron, Julio Sale, Tom Lyverse, Mark eng Research Support, Non-U.S. Gov't 2014/07/22 Ground Water. 2015 Jul-Aug; 53(4):658-67. doi: 10.1111/gwat.12240. Epub 2014 Jul 18"