Application of Four Measurement Techniques to Understand Natural Source Zone Depletion Processes at an LNAPL Site

TRRP Training: 2022 Program

presented by: GSI Environmetal Inc.

Texas Risk Reduction Program regulations (TRRP; 30 TAC 350) establish consistent risk-based protocols for assessment and response to soil, groundwater, or surface water impacts associated with environmental releases of regulated wastes or substances.

Presented by GSI Environmental Inc., this popular and informative training series is a must for professionals who need a working understanding of TRRP and those needing to stay up-to-date with the latest TCEQ TRRP guidance and policies.

TRRP Training Course (2 Days): Provides an overview of the TRRP framework and step-by-step training on property assessment and response action procedures established under the TRRP rule

Attendees will become acquainted with rules, key guidance and policies covering affected property assessments, protective concentration levels, and response actions. The course material presents strategies for efficient project management in compliance with TRRP and explains the various report forms adopted by TCEQ.

Dates and Location

Dates

June 14th and 15th, 2022

Location

Crowne Plaza River Oaks 2712 SW Freeway Houston, Texas 77098 713.523.8448 http://www.crowneplaza.com/

Price and Registration

Early-Bird Price

(Paid by May 1, 2022)
$XXX

Standard Price

(Paid after May 1, 2022)
$XXX

TAEP Membership Price

$XXX

Government Price

$XXX

Lodging and meals are not
included in course cost

Authors: Poonam R. Kulkarni, Charles J. Newell, David C. King, Lisa J. Molofsky, Sanjay Garg

Published: July 2020 in Groundwater Monitoring and Remediation.

Abstract

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There are several key data gaps in our understanding of Natural Source Zone Depletion (NSZD) processes at sites impacted by light nonaqueous phase liquid (LNAPL), and quantifying NSZD rates can be challenging due to the inherent differences in measurement methods. In this study, four different NSZD measurement methods (oxygen influx measured by the Gradient Method, long‐term carbon dioxide efflux measured with Carbon Traps, instantaneous carbon dioxide efflux measured with Dynamic Closed Chambers (DCC LI‐COR), and the long‐term heat flux from biodegradation measured by Thermal NSZD monitoring), as well as LNAPL composition and dissolved gas sampling, were applied at a site in Southern California. These techniques were used to evaluate key questions such as: (1) how do different NSZD rate measurement methods compare, and what causes variability in NSZD results?; (2) to what extent NSZD processes are occurring in LNAPL within the saturated zone?; and (3) how is NSZD related to LNAPL composition change over time? Carbon Traps and Thermal NSZD monitoring measurement methods provided the most consistent NSZD data at this geologically heterogeneous site, with two location average NSZD rates of 540 and 480 gal/acre/year, respectively. Overall, comparisons of NSZD rates between methods were challenging due to different measurement timeframes, significant temporal and spatial heterogeneity, and operational challenges with two of the NSZD methods. Finally, samples of subsurface LNAPL were collected for analysis in 2007 and 2016; results indicated that diesel‐range constituents were already very degraded and anaerobic degradation of gasoline‐range constituents was ongoing. A LNAPL depletion model (Douglas et al. 1996) applied to the measured LNAPL composition change appeared to greatly overestimate the amount of LNAPL depletion compared to the measured NSZD rate, but did provide an independent semiqualitative line of evidence that LNAPL was being depleted by active NSZD processes at the site.