implementation performance thermally enhanced ... · unit inj‐30 and eab‐1 performance...

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

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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


~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


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


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


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


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


System Operation

System Operation

COPC Molar Concentrations at Nearby Wells


System Operation

System Operation

COPC Molar Concentrations at Nearby Wells –INJ‐30 Area


System Operation

System Operation

1,1,2,2‐PCA Extent


TCE Extent


Cis‐1,2‐DCE Extent


Trans‐1,2‐DCE Extent


Vinyl Chloride Extent


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


Questions?

DNAPL perched on Qpf silt unit at EAB‐1 And a well drillers dream…

implementation performance thermally enhanced ... · unit inj‐30 and eab‐1 performance...

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