PCK Schwedt refinery site
Long term groundwater monitoring and natural attenuation
Patrick Jacobs, Tauw Germany Project site, North-East Germany
Germany Refinery site PCK Schwedt
Berlin
2 Location
Welse River Oder Refinery site PCK Schwedt
3 Production areas
Tank farm
AWBA
WZF Verladung
Former fertilizer production Hydrocarbon production
Tank farm 4 Site history
19745 1981 Substances handled
- Petrol, - Diesel - Kerosin (Jet A1) - Fuel oil, - MTBE + ETBE, - BTEX, …
6 Ongoing water production andcontainment: total abstraction rate 3 · 106 m³ per year
GroundwaterLocal GW remediationabstraction
AWBA
WZF Verladung
LNAPL recovery Local GW (dynamic) remediation 7 LNAPL and BTEX in groundwater (2011)
8 What is the problem to be solved?
• Huge potential of hydrocarbons results in long-term release to the groundwater. • Options for source remediation strongly limited by lack of accessibility • Hydraulic containment results in large-scale draw down and vertical LNAPL dislocation
MNA or ENA are most promising options for a sustainable management Approach: Site characterization and analysis of ongoing NA processes
Mass balances of contaminants
Efficiency of natural attenuation by analysis of flow lines
Evidence for microbial degradation by specific metabolites
Contaminant plume development with time (trend analysis using Mann-Kendall test)
Redox environment (monitoring sensitive parameters; screening tool: BOS-NA)
Geo-hydraulic conditions 10 Investigation of NA potential: redox processes Groundwater monitoring since 1970
• Number of monitoring wells: ~ 420 • Sampling campaigns: 2 per year • Parameters: - Meteorological data, groundwater recharge - Groundwater abstraction rates - Water level data (~ 420 piezometers) - LNAPL thickness - Contaminant concentration (BTEX, MTBE, etc., ca. 100 – 200 wells) - - Redox parameters (O2, NO3, SO4, S , Fe, Mn, CH4)
- Fe, Mn, CH4, CO2/HCO3, specific metabolites • Data management tool: GeODin
12 Favorable redox conditions vor NA? Screening scheme from the Dutch BOS-NA
Nitrate reduction downstream the Sulfate reduction / former fertilizer methane formation production at / near source areas
13 Evidence for anaerobic degradation from specific metabolites?
Educts Metabolites • Benzyl succinic acid • Methylbenzene (Toluene) • Benzoic acid (unspecific) • Ethylbenzene • 2,3-dimethyl benzoic acid • Dimethylbenzene • 3,4-dimethyl benzoic acid • Trimethylbenzene • Methylethylbenzene • 3,5-dimethyl benzoic acid • p-Tolylacetic acid (unspec.) Metabolite occurrence in different redox settings µg/L 250,000
Summe Dimethyl- 200,000 benzoesäure p-Tolyl- 150,000 essigsäure Benzyl- 100,000 Bernsteinsäure Benzoesäure 50,000
0,000
sulfate red. oxisch iron reduction Fe-ReduktionFe-ReduktionFe-ReduktionFe-ReduktionFe-ReduktionFe-Reduktion NitratreduktionNitratreduktion Sulfatreduktion nitrate red.
Nitratreduktion,Nitratreduktion, oxisch oxisch aerobic
Fe Reduktion,Fe Reduktion,Fe Sulfatreduktion Reduktion, Sulfatreduktion Sulfatreduktion Benzene degradation according to mass balance vs. upstream TEA
Aerobic / Nitrate 2,2 t (8 Aerob/%) Methane formation nitratreduzierend; 2,2 7,5 t (28Methanogenese; %) 7,5 Eisenreduzierend;Iron reduction 0,9 t0,85 (3 %)
Sulfatreduzierend;Sulfate reduct. 16,616,6 t (61,1 %) Stoffumsatz t Benzen pro Jahr
16 Investigation of plume stability Statistical evaluation of NA effectiveness using Mann-Kendall (MK) test
• Mainly stagnant conditions in the source zone indicating a continuous contaminant supply. • Local concentration trends are mainly associated with groundwater abstraction. • Analysis of the plume status in the sense of MNA is not possible in the zone influenced by extraction wells. Analyzing NA effectiveness along flow lines
AWBA 1-4 Schadenseintrag
Methanogenese Nitratreduktion
GW Sulfatreduktion Fe/Mn-Reduktion
range analysed 19 Analyzing NA effectiveness along flow lines
Monitoring Monitoring KORA (Test Site) -1 -1 k [d ] T(1/2) [d] k [d ] T(1/2) [d] 0,0016 430 d 0,003 – 0,042 17 - 230 d Benzene Ø 0,03 Ø 23 d 0,0073 95 d 0,066 – 0,439 2 – 11 d Toluene Ø 0,09 Ø 7 d Ethylbenzene 0,0010 690 d Xylene 0,0013 530 d
20 Abbaubarkeit von Aromaten nach A. Geller NA based groundwater management concept IGM concept
• Concept IGM = Integrated Grondwater Management • Largescale contamination requires integral approach to remediation • (Re-)infiltration of (ground) water with high TEA concentrations • to compensate groundwater abstraction from containment and process water production • to stabilise ground water levels and, by that, to avoid smearing of the LNAPL layers • to enhance microbial degradation
22 IGM concept
• Pilot-scale infiltration of stormwater runoff and water drained from the adjacent agricultural land • NO3 > 10 mg/L
• SO4 ca. 200 mg/L
23 Summary
• Analysing the redox environment, the specific metabolites, and the field degradation rates in concert with balancing the TEA mass flow with the groundwater showed effective contaminant degradation at anaerobic conditions. • The contaminant plumes were shown to be largely stable or retrograding. • An integrated management concept including the amendment with TEAs is expected to increase the efficiency of the NA processes.
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