Lessons learned from injecting liquid activated carbon suspension
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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.
Lessons learned from injecting liquid activated carbon suspension
- 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