PCK Schwedt refinery site

Long term groundwater monitoring and natural attenuation

Patrick Jacobs, Tauw Project site, North-

Germany Refinery site PCK Schwedt

Berlin

2 Location

Welse River 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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