Research authored by Keith M. Gaskill, LPG from EnviroForensics; Douglas A. Davis; Steve Barnes from Regenesis

1. RESEARCH POSTER PRESENTATION DESIGN © 2015
www.PosterPresentations.com
SITE 1
COLLOIDAL LIQUID ACTIVATED CARBON ONLY
SITE 3
COLLOIDAL LIQUID ACTIVATED CARBON
ELECTRON DONOR
BIOAUGMENTATION
Keith M. Gaskill, LPG; Douglas A. Davis; Steve Barnes
EnviroForensics, LLC (EnviroForensics) and Regenesis, Inc.
MATERIALS AND METHODS
ABSTRACT
Utilizing Colloidal Liquid Activated Carbon to Control Back-Diffusive Mass Loading at Three Midwest Sites with Glaciogenic Interbedded Geology
SITE 2
COLLOIDAL LIQUID ACTIVATED CARBON
ELECTRON DONOR
BIOAUGMENTATION
Three individual case studies have been compiled to demonstrate a
remediation technique intended to achieve similar results at each individual
site. All of these sites are impacted with chlorinated solvents with
groundwater plumes that are considered to be mature stage. Which means that
mass loading is occurring from clay formations above, below, or within the
sand unit transporting the dissolved phase plume. In these cases, most of the
chlorinated solvent mass that would result in loading into the transport zone
has been remediated or attenuated. Back diffusion is a common and well
understood late plume phenomenon that slowly continues to load the plume for
many years into the future if not treated. Colloidal Liquid Activated Carbon
(PlumeStop) from REGENESIS was applied to sandy transport zones
surrounded by clay storage zones to sequester chlorinated solvent mass
diffusing from the clay units. The approach included initial and continual
design verification over the aerial extent of the injection area. The initial
verification at two of the sites established the radius of influence that the
transport zone would allow. The continual design verification was needed to
confirm the injection interval and potential dosing alterations within each
injection zone. The distribution analysis, where conducted, demonstrated a
complete coverage of the sediments within the transport zone and along the
clay units in contact with the sand. This indicates that the liquid activated
carbon is properly distributed and should be effective in removal of back
diffused contaminants and will theoretically be effective for a significant time
period unmatched by other technologies based on manufacturer’s estimates.
SITE 3 RESULTS
AUTHORS
0
1,000
2,000
3,000
4,000
1/31/2016 5/10/2016 8/18/2016 11/26/2016 3/6/2017 6/14/2017 9/22/2017 12/31/2017 4/10/2018
PPB
DATE
MW-7 PCE and TCE
PCE
TCE
Remediation
0.0
50.0
100.0
150.0
200.0
5/10/2016 8/18/2016 11/26/2016 3/6/2017 6/14/2017 9/22/2017 12/31/2017 4/10/2018
PPB
DATE
MW-10 PCE and TCE
PCE
TCE
Remediation
0
200
400
600
800
1000
1200
4/1/2012 8/14/2013 12/27/2014 5/10/2016 9/22/2017 2/4/2019
PPB
DATE
PCE at MW-1 and MW-6
MW-1
MW-6
Remediation
0.0
20.0
40.0
60.0
80.0
100.0
4/1/2012 8/14/2013 12/27/2014 5/10/2016 9/22/2017 2/4/2019
PPB
DATE
PCE at MW-2, MW-4 and MW-5
MW-2
MW-4
MW-5
Remediation
Remediation Objective: Obtain closure by eliminating back diffusion flux
from PCE and daughter products into the sand transport zone. Minimize
daughter product formation and minimize rebound. Main soil source
removed through excavation.
Design Verification: Prior to injection activities, EnviroForensics and
REGENESIS Remediation Services (RRS) advanced 8 soil cores in the
injection area to verify the desired injection zone thickness and depth to
ensure an effective application. The target injection zone varied by as much
as five feet in depth and three feet in thickness. The design verification
proved to be very valuable in this type of injection to assure prevention of
back diffusive mass loading. Cores were collected before and after the
injection event.
Remediation Design:
• 6,393 gallons of reagent solution was pumped into 24 direct push injection points
in a grid pattern at a concentration of 6,000 mg/L.
Remediation Objective: Obtain closure by eliminating back diffusion flux into
the sand transport zone in two distinct areas. The source area required increased
dosage and volume per point. The dilute plume mass area was treated by a
barrier wall to prevent downgradient migration. An electron donor to aid in
enhanced biological reduction was injected for utilization by naturally occurring
microbes. The microbe population was also augmented.
Remediation Objective: This project was completed as an interim measure to remediate onsite
TCE impact for a financial transaction as well as to provide a line of evidence in identifying
multiple offsite/downgradient sources to the overall plume. The chlorinated solvent plume is
shown on the above-left figure.
Remediation Design:
• In the source area; 3,836 gallons of reagent solution was injected into 6 semi-permanent 1” PVC
injection points in a semi-grid pattern.
• A barrier wall consisting of 4,795 gallons of reagent solution injected into 12 points was completed
• Dosing consisted of a concentration of 6,000 mg/L.
• A total of 660 pounds of electron donor and 17 liters of bioaugmentation substrate was injected in
total.
Design Verification: Prior to injection activities, EnviroForensics and RRS
advanced 3 soil cores in the injection area to verify the desired injection zone
thickness and depth. Two cores were collected along the barrier wall, while one
was collected near the location of the interior borings. The verification allowed
for changes to be made to the initial design. Due to experiencing tighter soils
than expected, the barrier was extended from 10 points to 12 to account for the
smaller expected ROI. Indoor drilling constraints and space issues limited the
interior borings from 10 to 6. Thus, the volume and dosage of the injectate was
similarly adjusted as the project progressed.
Representative section of sandy zone of profile
before injection event
Representative section of sandy zone of profile
after injection event. Note coloration change
due to activated carbon addition
Remediation Design:
• The above-right figure shows the injection grid and barrier sectioned out to account for the size of the site and
variability in geology and plume concentration.
• The west grid (sections 1-4) represents the most impacted area and had 11,504 gallons of reagent (20,000
mg/L) injected along with 3,600 pounds of electron donor with 35 liters of bioaugmentation substrate.
• The east grid (sections 1-7) had 24,766 gallons of reagent (15,000 mg/L) injected along with 5,400 pounds of
electron donor and 64 liters of bioaugmentation substrate.
• The barrier wall had 22,000 gallons of reagent (5,000 mg/L) injected along with 1,530 pounds of electron
donor and 16 liters of bioaugmentation substrate.
Design Verification: Prior to injection activities, EnviroForensics,
REGENESIS technical staff, and RRS first conducted a Radius of Influence
(ROI) test to determine if the planned ROI was adequate to accomplish
remediation plans. A point of initial injection was selected, and observation
points were installed at distances of 5 ft, 7.5 ft, 12.5 ft., and 15 ft. During the
test, the reagent was injected and bailers in each of the observation locations
were utilized for visual evidence of the reagent. The fluid was observed in the
12.5 ft. distance, but not the 15 ft. distance verifying the conservatively
designed spacing of 20 ft. between points in the interior grid areas would be
sufficient to ensure lateral coverage The second phase of verification testing to
was establish distribution within the transport zone of the soil. After the ROI
testing was completed, a soil core was collected 5 feet from the injection point
examine and confirm distribution of the liquid activated carbon substrate
through the transport zones. Shown on the right is the core collected nearby the
ROI injection location for a distribution analysis.
Ongoing Design Verification: As the remediation project advanced, a test soil
boring was advanced at each treatment zone section to establish the depth and
thickness of the sand unit. Many times over the course of this remediation
project; the number of points, dosing within points, order of points (to keep the
warehouse operation active), and site logistics such as deliveries of product and
water, had to be continually updated by the REGENESIS, RRS, and
EnviroForensics project team. A QuantArray-Chlor (Microbial Insights)
biological assessment of dechlorinating microbes was completed both before
and shortly after the injection event. The results showed a distinct bloom in
microbial populations in groundwater indicating that the carbon sites were
bioavailable and the remedial action was proceeding as planned.
Above: The ROI testing location. Pumping was started at the location to the left
and observed at the three points to the right.
Above: Core completed after injection event. Note colloidal liquid activated
carbon in the fourth core section and part of the fifth (left to right). This 16-22 foot
depth represents the targeted transport zone sand lens.
Above: After the injection event, the water in most monitoring wells in the
injection area were found to have liquid activated carbon in groundwater collected
from them demonstrating proof of concept.
Above: A core completed following the ROI testing revealed the activated carbon
present in the sand seam.
Above: Colloidal Activated Carbon observed in groundwater at a point 5 feet from
the pumping location.
Figure demonstrates the design principle for back diffusion control. Target the
sand transport zone that is experiencing matrix diffusion from the clay storage
zones thereby sequestering the contaminants for subsequent bioremediation.
Baseline Concentration
Contour Map
• TCE impact present on the
target property and
extends offsite to the
southwest.
192 Day Post-Remediation
Concentration Contour Map
• TCE impact removed from
the target property
• Potential offsite source(s) to
the south and southwest
appears likely.
101 Day Post-Remediation
Concentration Contour Map
• TCE impact almost
removed from the target
property yet extends offsite
to the southwest.
• Potential offsite source(s)
to the south and southwest
potentially identified.
31 Day Post-Remediation
Concentration Contour Map
• TCE impact greatly reduced
on the target property yet
extends offsite to the
southwest.
CONCLUSIONS
• Colloidal Liquid Activated Carbon was applied to three sites in
Midwestern glacial terrain where a transport sand unit was
underlain and overlain by storage clay units. Back diffusive
loading to the sand unit was occurring in each case.
• The objective at each site was to control back diffusion mass
loading to a transport sand unit.
• In each case, greater than 95% reduction has occurred in target
compounds in two quarters or less.
Keith M. Gaskill. LPG, Chief Geologist, EnviroForensics, Indianapolis, IN kgaskill@enviroforensics.com
Douglas A Davis, Senior Design Specialist, Columbus, OH ddavis@regenesis.com
Steve Barnes, Remediation Services Director of Operations, Mishawaka, IN sbarnes@regenesis.com