PCK Schwedt refinery site

Long term groundwater monitoring and natural attenuation

Patrick Jacobs, Tauw Germany

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Project site, North-East Germany

Refinery site PCK Schwedt

Berlin

Germany

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Location

Welse River Oder

Refinery site PCK Schwedt

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Production areas

Verladung

AWBA

WZF

Tank farm

Former fertilizer production Hydrocarbon

production Tank farm

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Site history

1974 1981

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Substances handled

- Petrol,

- Diesel

- Kerosin (Jet A1)

- Fuel oil,

- MTBE + ETBE,

- BTEX, …

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Ongoing water production andcontainment: total abstraction rate 3 · 106 m³ per year

Verladung

AWBA

WZF

LNAPL recovery (dynamic) Local GW

remediation

Local GW remediation

Groundwater abstraction

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LNAPL and BTEX in groundwater (2011)

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

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Approach: Site characterization and analysis of ongoing NA processes

Geo-hydraulic conditions

Redox environment (monitoring sensitive parameters; screening tool: BOS-NA)

Contaminant plume development with time (trend analysis using Mann-Kendall test)

Evidence for microbial degradation by specific metabolites

Efficiency of natural attenuation by analysis of flow lines

Mass balances of contaminants

Investigation of NA potential: redox processes

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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

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Favorable redox conditions vor NA? Screening scheme from the Dutch BOS-NA

Sulfate reduction / methane formation at / near source areas

Nitrate reduction downstream the former fertilizer production

Evidence for anaerobic degradation from specific metabolites?

•  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.)

•  Methylbenzene (Toluene) •  Ethylbenzene

•  Dimethylbenzene

•  Trimethylbenzene

•  Methylethylbenzene

Educts Metabolites

0,000

50,000

100,000

150,000

200,000

250,000

Sulfatre

dukti

on

Fe Red

uktio

n, Sulfa

tredu

ktion

Fe Red

uktio

n, Sulfa

tredu

ktion

Fe Red

uktio

n, Sulfa

tredu

ktion

Fe-Red

uktion

Fe-Red

uktion

Fe-Red

uktion

Fe-Red

uktion

Fe-Red

uktion

Fe-Red

uktion

Nitratre

dukti

on

Nitratre

dukti

on

Nitratre

dukti

on, o

xisch

Nitratre

dukti

on, o

xisch

oxisc

h

Summe Dimethyl-benzoesäurep-Tolyl-essigsäureBenzyl-BernsteinsäureBenzoesäure

Metabolite occurrence in different redox settings

sulfate red.

iron reduction

nitrate red.

aerobic

µg/L

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Benzene degradation according to mass balance vs. upstream TEA

Stoffumsatz t Benzen pro Jahr

Sulfatreduzierend; 16,6

Methanogenese; 7,5

Aerob/ nitratreduzierend; 2,2

Eisenreduzierend; 0,85

Methane formation 7,5 t (28 %)

Aerobic / Nitrate 2,2 t (8 %)

Iron reduction 0,9 t (3 %)

Sulfate reduct. 16,6 t (61,1 %)

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.

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Analyzing NA effectiveness along flow lines

Schadenseintrag

Methanogenese

Sulfatreduktion

Nitratreduktion

AWBA 1-4

Fe/Mn-Reduktion

GW

range analysed

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Monitoring

Monitoring KORA (Test Site)

k [d-1] T(1/2) [d] k [d-1] T(1/2) [d]

Benzene 0,0016 430 d 0,003 – 0,042

0,03 17 - 230 d

23 d

Toluene 0,0073 95 d 0,066 – 0,439

0,09 2 – 11 d

7 d

Ethylbenzene 0,0010 690 d

Xylene 0,0013 530 d

Analyzing NA effectiveness along flow lines

Ø Ø

Ø Ø

Abbaubarkeit von Aromaten nach A. Geller

NA based groundwater management concept

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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

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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

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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.