Learn how Antea Group helped their gas station client with a once-leaking UST help remediate off-site groundwater using a sorptive biobarrier.
This was presented at the AEHS Conference in San Diego, California.
Tracking Full-Scale Performance of an Injectable Sorptive Biobarrier: One Year and Beyond
1. Tracking Full-Scale Performance of an
Injectable Sorptive Biobarrier:
One Year and Beyond
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4. The History
• Operating gas station with prior leaking UST
• Prior remedial efforts to clean up BTEX and TPH-GRO
successful using AS/SVE
• Minimal impacts remain on-site. Off-site groundwater is the
current focus (<10 lbs. of MTBE mass in groundwater)
• Groundwater table at 32 ft. bgs
• San Mateo County Groundwater Protection Program oversees
the site
5. The History (continued)
• MNA important polishing on-site
• Site responded well to increased dissolved oxygen
• Plume migration through narrow channels of sand and limited
to a 5 ft. vertical horizon – 32 ft. – 37 ft. bgs
• Expansion of AS/SVE or switch to P&T for off-site riddled with
logistical issues and costly
6. Site Geology
6
~12 ft. to 37-38 ft. bgs: Poorly
sorted primarily sand (SP) with
some interbedded silt and clay
38 ft. to 45 ft. bgs: Continuous
clay layer (aquitard) found in all
borings south of most
downgradient wells
10. • MW-8, 10, 11, and 14 used for
microcosm testing
• Water column height dictated
specific approach per well
• Sulfate and ORC-A® addition
allowed comparison to
unamended control
• PM-1 organism (MTBE degrader)
and MTBE/TBA gene functions
analyzed
• 13C labeled MTBE used to show
microbial growth versus actual
degradation
Microbial Results
13. The Chemistry
1.
Fine particle
activated
carbon (1-2
microns)
2.
Combined with
unique
polymer for
distribution
enhancement 3.
Binds to aquifer
solids.
Establishes
biodegradation
site
4.
Regeneration
occurs
14. Bench Test Results
14
Baseline
1
Baseline
2
Control
1
Control
2
Treated
1
Treated
2
Analyte (µg/L) 3/10/16 3/10/16 3/31/16 3/31/16 3/31/16 3/31/16
1,2 Dichloroethane 41 34 34 34 < 5.0 < 5.0
MTBE 6,400 6,200 6,800 7,100 530 590
tert-Amyl methyl
ether 48 50 62 60 < 5.0 < 5.0
tert-Butanol < 10000 < 10000 580 540 < 100 < 100
Total VOCs 6,489 6,284 7,476 7,734 530 590
Average Total VOCs 6,386.5 7,605 560
% Removed (comp.
Control) --- --- 93%
Groundwater sample
collected from MW-14
Two doses of
PlumeStop® tested
Calcium salts added to
drop out amendment
prior to extraction and
analysis
Experiment designed for
no volatilization
16. • Direct push PlumeStop® at MW-14
and MW-24 (locations exceeded goal)
• Direct push ORC-A® to enhance
biodegradation 30 days later
• Three injection points per well per
amendment
• Monitor every two weeks for
MTBE/TBA and secondary parameters
– geochem/field parameters/microbial
(RNA vs DNA)
• Remedial goal – 1 mg/L MTBE
Pilot Test Approach
22. Lessons Learned
• Direct push injection into sand is not always what it
appears
• A bioamendment can be an important addition to the
carbon-based amendment, but natural conditions can
still support biodegradation
• With the right microbiology and conditions, substantial
reduction in MTBE/TBA concentrations is possible
• 5 points per day is reasonable production rate
24. • Four biobarriers installed to
protect downgradient municipal
well approximately 600 ft. away
• X lbs. of PlumeStop® per direct
push point, X lbs. of PlumeStop®
per injection well
• Six performance monitoring wells
MW-14, 21, 24, 26, 27 and 28 will
be monitored quarterly. 50%
reductions at MW21 and MW-28
at 30 days
Full Scale Biobarrier Application
28. 1
10
100
1,000
10,000
100,000
4/1/12 12/22/12 9/13/13 6/5/14 2/25/15 11/17/15 8/8/16 4/30/17 1/20/18 10/12/18
Concentration(MTBE,µg/L)
MTBE and TBA versus Time
76 (Former BP) Service Station 11202
Daly City, California
MTBE
(ug/L)
TBA
(ug/L)
PlumeStop Injection (Pilot) ORC-A Injection (Pilot) PlumeStop Injection
MW-14
29. 1
10
100
1,000
10,000
100,000
4/30/16 8/8/16 11/16/16 2/24/17 6/4/17 9/12/17 12/21/17 3/31/18 7/9/18 10/17/18
Concentration(µg/L)
MTBE and TBA versus Time
76 (Former BP) Service Station 11202
Daly City, California
MTBE
(ug/L)
TBA
(ug/L)
PlumeStop Injection (Pilot) ORC-A Injection (Pilot) PlumeStop Injection
MW-24
30. 1
10
100
1,000
10,000
100,000
7/15/15 1/31/16 8/18/16 3/6/17 9/22/17 4/10/18 10/27/18
Concentration(µg/L)
MTBE and TBA versus Time
76 (Former BP) Service Station No 11202
Daly City, California
MTBE (ug/L) TBA (ug/L) PlumeStop Injections
MW-21
31. 1
10
100
1,000
10,000
100,000
4/25/17 8/3/17 11/11/17 2/19/18 5/30/18 9/7/18
Concentration(µg/L)
MTBE and TBA versus Time
76 (Former BP) Service Station No 11202
Daly City, California
MTBE (ug/L) TBA (ug/L) PlumeStop Injections
MW-28
33. Future Considerations
Will the microbiology
remain robust
Was distribution sufficient
at all injection locations
Will we have to inject an
electron acceptor
34. Acknowledgements:
Dacre Bush, PG (Antea Group Long Beach)
Craig Sandefur and Dan Nunez (Regenesis)
Gregg Drilling
Microbial Insights
35. We do more than effectively solve
client challenges; we deliver
sustainable results for a better future.
Thank you
If you have more questions…
Jack Sheldon
Antea Group
Senior Professional