implementation performance thermally enhanced ... · unit inj‐30 and eab‐1 performance...
TRANSCRIPT
10/03/2019
Implementation and Performance of Thermally‐Enhanced Bioremediation for Targeted DNAPL
Source Treatment
August Welch
Zoom Nguyen
Tamzen W. Macbeth
Dominic J. Giaudrone
Randa E. Chichakli
Christopher Cora
Kira Lynch
Thomas Powell
Presentation Outline
Site Background
Design and Installation of Thermally‐Enhanced Bioremediation System
System Operation and Monitoring
Results
2
Commencement Bay/South Tacoma Channel Well 12A Superfund Site, Tacoma, WA Six primary contaminants of
concern (COCs) in soil and groundwater PCE, TCE, cis and trans 1,2‐DCE, vinyl
chloride, 1,1,2,2‐tetrachloroethane
ROD Amendment #2 completed in 2009 Multi‐component remedy including
enhanced anaerobic bioremediation and in situ thermal remediation
Target is 90% reduction in contaminant mass discharge from source areas
3 Well 12A Superfund Site
Bioremediation (EAB) Area
In‐Situ Thermal Remediation
(ISTR) Area (high temperature)
Thermally Enhanced Bioremediation (EAB) Locations
(low‐temperature)
INJ‐30
EAB‐1
Well 12A Bioremediation Remedy
Implemented in 2014‐2015 Targeted treatment of the Qpf silt
unit Shear‐thinning fluids used to
distribute amendments to the silt unit
During implementation, two localized areas were found to contain DNAPL above the Qpf silt unit INJ‐30 and EAB‐1
Performance monitoring indicated that enhanced mass transfer was occurring in DNAPL areas
Accelerated degradation needed to meet project objectives
4 Well 12A Superfund Site
~242 kg VOC
~49 kg VOC
~148 kg VOC
~462 kg VOC
Bioremediation
Thermal
Why Thermally‐Enhanced Bioremediation? Increased biodegradation
kinetics occur at temperatures between 35 and 45 degrees Celsius
Enhanced rate of hydrolysis reactions 1,1,2,2‐PCA to TCE
Elevated temperatures lead to enhanced dissolution of DNAPL Additional VOC flux off of
DNAPL source
5 Well 12A Superfund Site
Imhoff, et al. (1997)
ESTCP ER‐0719, 2012
Why Electrical Resistance Heating?
ERH allows for more even heating across the target interval without formation of “hot spots” around heater wells Localized hot spots could lead
to boiling of groundwater or be detrimental to microbial populations
Ability to target specific temperature ranges
6 Well 12A Superfund Site
EAB‐1
INJ‐30
ERH System Description
Array of three electrodes installed around each DNAPL hot spot
Targeted depth intervals within and immediately above Qpf silt unit INJ‐30: Silt interval 52‐54’. Heated
interval ~42‐52’ EAB‐1: Silt interval 49‐54’, Heated
interval ~40‐50’
Temperature monitoring at INJ‐30 and EAB‐1 (depth intervals 44, 48, and 52 ft bgs)
Able to utilize existing 3 phase, 480V electrical service at site
DNAPL recovery pumps installed
7 Well 12A Superfund Site
Upper Qpf Silt
Lower Qpf Silt
DNAPL Interval
Target Heated Interval
System Operation
Startup in August 2015 Initial target temperature 30 °C Coincided with municipal well
field pumping and increased hydraulic gradient
Incremental increases in temperature to 45°C ‐ 50°C
EAB‐1 shut down in October 2016
INJ‐30 shut down in February 2017
8 Well 12A Superfund Site
Cessation of Municipal Pumping
Operation of GETS
Results
Map of Monitoring and Injection Well Locations
INJ‐30
Groundwater Flow During Municipal Pumping
COPC Molar Concentrations at DNAPL Wells
11 Well 12A Superfund Site
System Operation
System Operation
COPC Molar Concentrations at Nearby Wells
12 Well 12A Superfund Site
System Operation
System Operation
COPC Molar Concentrations at Nearby Wells –INJ‐30 Area
13 Well 12A Superfund Site
System Operation
System Operation
1,1,2,2‐PCA Extent
14 Well 12A Superfund Site
TCE Extent
15 Well 12A Superfund Site
Cis‐1,2‐DCE Extent
16 Well 12A Superfund Site
Trans‐1,2‐DCE Extent
17 Well 12A Superfund Site
Vinyl Chloride Extent
18 Well 12A Superfund Site
Summary of Results
Thermally‐enhanced bioremediation operated for approximately 18 months Total energy applied 150,000 kWh
Temperatures were controlled within a 5°C specified range Ranges were between 30°C and 50°C at various times during operation
Degradation rates accelerated both within DNAPL hot spots and surrounding monitoring wells Increasing flux of chloride at all wells within heated areas
EAB‐1 DNAPL source was exhausted after approximately 12 months of operation EAB‐1 source hydraulically connected to preferential flow paths in aquifer
INJ‐30 DNAPL dissolution was enhanced, and declining concentration trend by end of operation Degradation of compounds occurred in a “halo” around the heated area INJ‐30 source is more hydraulically isolated from preferential flow pathways
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Acknowledgements
CDM Smith Julee Trump
Mark Jusayan
Mary Lou Fox
TRS Group, Inc. Lynette Stauch
Doug Seiler
Emily Crownover
EPA Region 10 Rene Fuentes
United States Army Corps of Engineers Karl Kunas
Maleena Lemiere
20 Well 12A Superfund Site
Questions?
DNAPL perched on Qpf silt unit at EAB‐1 And a well drillers dream…