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.

1. Tracking Full-Scale Performance of an
Injectable Sorptive Biobarrier:
One Year and Beyond
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2. The Site Bench/Pilot Testing Full-Scale Application

3. From the Sky:
76 Station
Daly City
California

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

7. Groundwater
Flow
Direction
Groundwater Elevation
Contours (A Zone)
September 17, 2018

8. Molecular Biological Tools and Geochemistry

9. In Situ Microcosms
GEO
COC
MICRO
Supplier
MNA
BioStim
BioAug

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

11. The Site Full-Scale ApplicationBench/Pilot Testing

12. The Chemistry
12

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

15. Pilot Test
Monitoring
Wells:
MW-14/24
15
MW-24
MW-14

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

17. Injection Highlights

18. The Results: MW-14
50
100
150
200
250
300
1,000
2,000
3,000
4,000
5,000
6,000
7,000
8,000
8/14/13 3/2/14 9/18/14 4/6/15 10/23/15 5/10/16 11/26/16 6/14/17 12/31/17
Concentration(TBAug/L)
Concentration(MTBE,µg/L) MTBE, TBA, versus Time
Former 76 Service Station 11202
Daly City, California
MTBE
(ug/L)
Plume Stop Injection ORC-A Injection Plume Stop Injection TBA
(ug/L)
9.43 µg/L

19. The Results: MW-24
0
1000
2000
3000
4000
5000
6000
7000
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
4/30/16 8/8/16 11/16/16 2/24/17 6/4/17 9/12/17 12/21/17
Concentration(TBA,ug/L)
Concentration(MTBE,µg/L)
MTBE, TBA versus Time
Former 76 Service Station 11202
Daly City, California
MTBE
(ug/L)
Plume Stop Injection ORC-A Injection TBA
(ug/L)
114 µg/L

20. Secondary Results: MW-14
-150
-100
-50
0
50
100
150
0
0.5
1
1.5
2
2.5
3
3.5
4
1/31/16 3/21/16 5/10/16 6/29/16 8/18/16 10/7/16 11/26/16 1/15/17
ORP,mV
Concentration(DO,mg/L)
DO, ORP, versus Time
Former 76 Service Station 11202
Daly City, California
Oxygen, Dissolved
(mg/L)
Plume Stop Injection ORC-A Injection

21. Secondary Results: MW-24
-250
-200
-150
-100
-50
0
50
100
150
200
250
0
0.5
1
1.5
2
2.5
3
3.5
4
1/31/16 5/10/16 8/18/16 11/26/16 3/6/17 6/14/17 9/22/17 12/31/17 4/10/18
OxidationReductionPotential(mV)
Concentration(ug/L)
DO, ORP versus Time
Former 76 Service Station 11202
Daly City, California
Oxygen, Dissolved… Plume Stop Injection

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

23. The Site Full-Scale ApplicationBench/Pilot Testing

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

25. Injection
Layout
12 injection wells
32 direct push
injection locations

26. Injection Challenges:
Night work
Major roadway requires lane closure
Infrastructure
Sands that compact

27. Photos from the field
27

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

32. 2019 Data
MTBE – January 2019
ND
ND
ND
21
ND
1,500
2,000
140
87
750
2,400
890
570
180
570
4.7
27
ND
ND
ND
ND
ND
MTBE – September 2018

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