IN SITU WORKSHOP RENARE MARK-2011 EXPERIENCE WITH TESTING INNOVATIVE REMEDIATION TECHNIQUES AT A DANISH MEGASITE Torben H. Jørgensen, Lars R. Bennedsen, Rambøll Lars Nissen, Jarl Dall Jepsen, Cowi Prasad Kakarla, ISOTEC Neal Durant, Leah MacKinnon, Geosyntec Prasad Kakarla, Isotec Mette Christophersen, Jørgen Fjeldsø Christensen, Region Syddanmark Preben Bruun, Miljøstyrelsen
PHASES AT THE KARGARD SITE FOR IN SITU REMEDIATION Site investigation Risc assesment Setup remediation objective and clean up criterias Feasability studies with remediation evaluation and recommendations (eg screening procedure) In situ test Laboraty test Pilot test ( ) Full scale remediation
KÆRGÅRD PLANTATION A COMPLEX MEGASITE
CONTAMINATION About 286,000 m 3 wastewater legally discharged in 6 waste pits from 1956-1973, including: 40,000 tons inorganic salt 15,000 tons organic acid salts 1,500 tons sulfonamides, barbiturates, aniline, pyridine, phenols, benzene, toluene. 340 tons chlorinated solvents Lithium, mercury, cyanide, etc.
50 YEARS AFTER DISCHARGING NOT A BIG DIFFERENCE
CONCENTRATIONS - MAXIMUM Soil (mg/kg) Water (ug/l) PCE >80.000 (DNAPL) 240.000 (DNAPL) Toluene 33.000 68.000 Benzene 5.000 93.000 Sulfonamides 10.000 760.000 Aniline 515 33.000 Barbiturates 4.000 27.000 Phenol 100 8.000 Lithium - 160.000 Cyanide 20.200 - Hg 5.560 <5 xx: most critical compounds
CONCEPTUAL MODEL Strong plume with CAH DNAPL? Strong mixed plume DNAPL
TARGET AREAS FOR REMEDIATION PHASE 1 (SOURCE AREA) 1 Area 1: Waste Pits/Vadose zone Sludge layer All contaminants Extremely contaminated DNAPL and NAPL 2 Area 2: Waste Pits Saturated zones Sand/gravel/silty sand Mixed contamination DNAPL Source area for PCE/BTEX
SELECTING COST-EFFECTIVE REMEDIATION METHODS Resistive/conductive Heating Metal Catalyzed Reduction Excavation Pump & treat Sheet pile walls Soil vapor extraction In situ flushing Airsparging ISCO-Fentons Steam Stripping??? Monitored Natural Attenuation ISCO-Permanganate ISCO-persulfate Reductive dechlorination ISCO-ozone Phytoremediation Challenges: - Complex mixture of contaminents - DNAPL - Large vertical distribution
REMEDIATION SELECTION
MOST COST EFFECTIVE REMEDIATION TECHNOLOGIES BASED ON FEASABILITY STUDIES In situ techniques Area 1: Waste Pits/vadose zone: 1 1. Escavation ex site thermal treatment (performed i 2007-2008) 2 Area 2: Waste Pits/saturated zone 1. ISCO: Fentons, Permanganate, Persulfate 2. Biological methods 3. Steam stripping
LABORATORY TREATABILITY TESTS SOURCE AREA - EFFICIENCY Metode PCE, TCE, DCE, VC BTEX Sulfona mider Anilin Barbiturater ISCO- Modified Fentons xxx xxx xxx xxx xxx ISCO Activ. Persulfate xxx xxx xxx xxx xxx Bio ERD high DNAPL x - - - - Bio ERD low DNAPL xxx - - - - Steam Stripping xxx xxx??? Xxx: High x-xx: Medium X: Low
2010 2011 PILOT TESTS Pilot Test 1: Fenton s Pilot Test 2: Sequenced Fenton s/erd Pilot Test 3: ERD Recirculation 13
MFR PILOT TEST Test 1: Modified Fentons - 8*8 m test cell - 5 multi-screen injection wells - 6 multi-screen monitoring wells - 4 injection events
MIXING OF CHEMICALS
MULTIPLE INJECTIONS WITH DIFFERENT TECHNIQUES TRADITIONEL SCREENED WELLS DIRECT PUSH TECHNIQUE
MFR PILOT TEST PRELIMINARY RESULTS Hydrogen peroxide is present 1-2 days after injection ph dropped to about 2-3 Reduction in PCE, TCE, benzene, and toluene in soil samples Bench test results were very useful for designing the pilot test Before MFR After MFR
TEST 3: ENHANCED REDUCTIVE DECHLORINATION M213 M212 AV1 M214 M206 M211 M205 I201
TEST 3: WELL PLACEMENTS Mixing container Injection well Injection well
TEST 3: MIXING CONTAINER Sodium Bromide Ethanol Sodium Lactate
17-jun 14-jul 12-aug 13-sep 07-okt 15-nov 21-dec 17-feb 23-mar Mole Fraction TEST 3: PRELIMINARY RESULTS 4 meter downstream injection well I201 1 M205-2 (6-8 m bgs) 100% Ethane 80% 60% 40% 20% 0% Ethene VC trans-dce c-dce TCE PCE 21
TEST 2: COMBINATION OF CHEMICAL OXIDATION AND BIOLOGICAL METHODS Buffer and After ISCO: ph: 2,5-3,5 Oxygen >20 mg/l Redox: +250 mv Sulfate: 900 mg/l Treatment Area No degradation After donor injection: ph: 6-7 Oxygen 0 mg/l Redox: -200 mv Sulfate: < 50 mg/l Degradation products
PRELIMINARY COMPARISON OF IN SITU METHODS AT THE KARGARD SITE ISCO Thermal Bio ISCO-Bio Treat contaminants All VOC Chlorinated ethenes All Treat DNAPL Yes Yes? Yes Effiency Moderate high High Moderate high? Moderate high? Cost Moderate high? High? Lowmoderate? Moderate? Time 1-3 years? 1 year 3-5 year? 3-5 year? Energy consumption Moderate - High High Low Moderate
PRELIMINARY CONCLUSION Cleaning up the Kargård site is very challenging - There are no experiences from similar sites In situ methods are the only cost effective remediation techniques in the saturated zone ISCO is the only stand alone method which can treat all the contaminants Steam stripping is the most efficiency methods to clean up DNPL-PCE Biological method is probably the cheapest and most climate friendly method Combination of in situ technologies seems to be necessary to reduce cost (treatment trains)
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