PCK Schwedt refinery site Long term groundwater monitoring and natural attenuation

Transcription

1 PCK Schwedt refinery site Long term groundwater monitoring and natural attenuation Patrick Jacobs, Tauw Germany

2 Project site, North-East Germany Germany Refinery site PCK Schwedt Berlin 2

3 Location River Oder Welse Refinery site PCK Schwedt 3

4 Production areas Tank farm AWBA Verladung WZF Former fertilizer production Tank farm Hydrocarbon production 4

5 Site history

6 Substances handled - Petrol, - Diesel - Kerosin (Jet A1) - Fuel oil, - MTBE + ETBE, - BTEX, 6

7 Ongoing water production andcontainment: total abstraction rate m³ per year Groundwater Local GW remediation abstraction AWBA Verladung WZF Local GW remediation LNAPL recovery (dynamic) 7

8 LNAPL and BTEX in groundwater (2011) 8

9 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

10 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

11 Investigation of NA potential: redox processes

12 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 wells) - Redox parameters (O 2, NO 3, SO 4, S -, Fe, Mn, CH 4 ) - Fe, Mn, CH 4, CO 2 /HCO 3, specific metabolites Data management tool: GeODin 12

13 Favorable redox conditions vor NA? Screening scheme from the Dutch BOS-NA Nitrate reduction downstream the former fertilizer production Sulfate reduction / methane formation at / near source areas 13

14 Evidence for anaerobic degradation from specific metabolites? Educts Metabolites Methylbenzene (Toluene) Ethylbenzene Dimethylbenzene Trimethylbenzene Methylethylbenzene Benzyl succinic acid Benzoic acid (unspecific) 2,3-dimethyl benzoic acid 3,4-dimethyl benzoic acid 3,5-dimethyl benzoic acid p-tolylacetic acid (unspec.)

15 Metabolite occurrence in different redox settings µg/l 250, ,000 Summe Dimethylbenzoesäure 150,000 p-tolylessigsäure 100,000 Benzyl- Bernsteinsäure 50,000 0,000 sulfate red. Sulfatreduktion ktion, Sulfatreduktion ktion, Sulfatreduktion ktion, Sulfatreduktion Fe-Reduktion Fe-Reduktion iron reduction Fe-Reduktion Fe-Reduktion Fe-Reduktion Fe-Reduktion Nitratreduktion Nitratreduktion itratreduktion, oxisch itratreduktion, oxisch nitrate red. oxisch aerobic Benzoesäure

16 Benzene degradation according to mass balance vs. upstream TEA Methane formation 7,5 t (28 %) Methanogenese; 7,5 Aerobic / Nitrate 2,2 t (8 %) Aerob/ nitratreduzierend; 2,2 Iron reduction 0,9 t (3 %) Eisenreduzierend; 0,85 Sulfate reduct. 16,6 t (61,1 %) Sulfatreduzierend; 16,6 16

17 Investigation of plume stability

18 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.

19 Analyzing NA effectiveness along flow lines Schadenseintrag AWBA 1-4 Methanogenese Nitratreduktion GW Sulfatreduktion Fe/Mn-Reduktion range analysed 19

20 Analyzing NA effectiveness along flow lines Monitoring Monitoring KORA (Test Site) k [d -1 ] T( 1/2 ) [d] k [d -1 ] T( 1/2 ) [d] Benzene 0, d 0,003 0,042 Ø 0, d Ø 23 d 0, d 0,066 0,439 Toluene Ø 0,09 Ethylbenzene 0, d 2 11 d Ø 7 d Xylene 0, d Abbaubarkeit von Aromaten nach A. Geller 20

21 NA based groundwater management concept

22 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

23 IGM concept Pilot-scale infiltration of stormwater runoff and water drained from the adjacent agricultural land NO3 > 10 mg/l SO 4 ca. 200 mg/l 23

24 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. 24