Three gas station sites in California were selected for pilot tests of injecting liquid activated carbon suspension to remediate contaminated groundwater. At the first site in San Jose, substantial contaminants desorbed initially but then total petroleum hydrocarbons declined over 60 days and stabilized. The second site in Oakland showed decreases in benzene and other contaminants within 2-3 months, meeting remedial goals. Lessons learned included that direct push injection may not distribute as expected, biostimulation aids carbon treatment, and substantial reductions are possible within months with the right conditions.

1. Lessons Learned from Injecting Liquid Activated Carbon Suspension
Background
Three gas station sites (two highlighted below) in California were
selected for beta testing of new in-situ sorption formulations. Pilot
test areas of 250 sq. ft. were targeted at each site and each test
spanned 180 days. Pilot tests included contaminant and geochem-
ical analysis along with field parameters and soil cores.
Beta Test Site #1, San Jose, CA Beta Test Site #2, Oakland, CA
Results of Beta Test #1
• Substantial desorption during first 30 days of test near former
UST area.
• TPHg and TPHd declined during 60 day post-injection sam-
pling event and stabilized for until the test ended at 180 days.
• Essentially no change in field parameters or geochemistry
during test, minor uptick in ORP/DO and TOC.
Results of Beta Test #2Table 1. Antea Group Groundwater Monitoring Data, 76 (former BP) SS No. 11117, 7210 Bancroft Avenue, Oakland, CA.
Well ID MW-4 DPT-1-36 DPT-2-32 DPT-2-40
Sample ID MW-4 MW-4 MW-4 MW-4 MW-4_20120930 DPT-1-36 DPT-2-32 DPT-2-40
Date Sampled 3/7/2012 4/27/2012 5/30/2012 6/27/2012 9/27/2012 3/7/2012 3/7/2012 3/7/2012
MonitoringEvent baseline 1 month 2 month 3 month 6 month baseline baseline baseline
Analyte Units ReportingLimit
Dissolved Oxygen (DO) mg/L -- 2.66 0.56 1.76 0.6 1.6
ORP (Redox Potential) mV -- -32.5 -244.3 -113.8 -110.9 -67.2
Conductivity µS/cm -- 1058 1242 1351 1215 1080
pH -- 6.64 6.55 6.55 6.53 6.56
Turbidity NTU -- 35 17 218 60 73
Temperature °C -- 19.83 22.17 20.52 19.02 17.44
Water Levels -- 17.76 13.67 15.33 16.51 20.65
Alkalinity, Total (as CaCO3) mg/L 5 525 742 496 510 556
Total Iron mg/L 0.1 4.55 4.89 5.62 8.33 27.1
Dissolved Iron mg/L 0.1 2.08 2.23 3.88 4.55 6.57
Methane µg/L 8 5,870 5,020 4,300 6,060 4,340 -- 1,880 4,790
Sulfate mg/L 1 -- 13 < 1.0 < 1.0 < 1.0
Sulfide mg/L 0.05 < 0.05 0.2 0.25 0.3 0.2
Nitrate (as N) mg/L 0.1 -- < 0.10 < 0.10 < 0.10 < 0.10
TOC mg/L 5 7.8 25 63 84 73
COD mg/L 5 63 120 100 78 520
TPH-G µg/L 50 8,500 17,000 17,000 16,000 58,000 4,900 5,700 2,400 .
Benzene µg/L 0.5 4,000 2,800 2,800 2,500 2,600 480 76,00 920
Ethylbenzene µg/L 1 480 1,500 1,400 1,100 7,700 170 760 58
Toluene µg/L 1 42 490 380 390 530 15 47 44
p/m-Xylene µg/L 1 890 2,500 2,000
2,400 15,000
710 78 150
o-Xylene µg/L 1 200 730 570 270 18 71
Methyl-t-ButylEther (MTBE) µg/L 1 400 370 210 250 160 11 13 11
Tert-Butyl Alcohol (TBA) µg/L 10 4,900 2,900 2,700 3,200 2,400 2,400 6,700 4,600
Diisopropyl Ether (DIPE) µg/L 2 < 50 < 50 < 50 < 50 < 100 < 10 < 2 < 2
Ethyl-t-Butyl Ether (ETBE) µg/L 2 < 50 < 50 < 50 < 50 < 100 < 10 < 2 3.7
Tert-Amyl-Methyl Ether (TAME) µg/L 2 < 50 < 50 < 50 < 50 < 100 < 10 < 2 < 2
Ethanol µg/L 100 < 200 < 2,500 < 2,500 < 2,500 < 5,000 < 500 < 100 < 100
Key to Abbreviations
TPH-G Total Petroleum Hydrocarbons - Gasoline Range
TPH Total Petroleum Hydrocarbons
ORP OxidationReduction Potential
TOC Total OrganicCarbon
COD Chemical Oxygen Demand
mg/L milligrams per liter
µg/L micrograms per liter
mV millivolts
µs/cm microseimens per centimeter
NTU NephelometricTurbidity Units
Approach
• Direct push PlumeStop® around MW-16R (Site A, 14 points)
and upgradient of MW-12S (Site B, 5 points).
• Direct push ORC-A® & HRC-A® to enhance biodegradation and
anaerobic biodegradation.
• Monitor at 2/3 and 6 months post-injection - BTEX, CVOC,
geochem/field parameters.
• Site A Remedial Goal = 5 µg/L benzene.
• Site B Remedial Goal = show decreases in mix of CVOCs.
Site Geology
• Critical in understanding transmissive zones.
• Soil cores are important to understand potential amendment
distribution issues.
• Water injection tests provide value.
The Chemistry
• Fine particle activated
carbon (1-2 microns)
• Combined with unique polymer for distribution
enhancement
• Binds to acquifer solids
• Establishes biodegradation site
• Regeneration occurs
Photos from the Field
Lessons Learned
1. Direct push injection into sand isn’t always what it appears.
2. A bioamendment is an imporant addition to the carbon-based
amendment.
3. With the right microbiology and conditions, substantial reduc-
tion in concentrations is possible within months.
4. Broad spectrum activity with PlumeStop®.
Site A Injection Area Site A Data
Site B Injection Area Site B Results
For more information, please contact:
Jack Sheldon
jack.sheldon@anteagroup.com
Antea Group, West Des Moines, IA,
USA
Craig Sandefur
CSandefur@Regenesis.com
Regenesis, San Clemente, CA, USA