1 Foster Wheeler Environmental Italy Eni Agip - Divisione ...dorsogna/byron/Trecate.pdf · blow out of trecate 24 crude oil well: how bioremediation techniques are solving a major

BLOW OUT OF TRECATE 24 CRUDE OIL WELL: HOW BIOREMEDIATION

TECHNIQUES ARE SOLVING A MAJOR ENVIRONMENTAL EMERGENCY IN A

VALUABLE AGRICULTURAL AREA (Trecate, ITALY)

D. Arlotti1, G. Andreotti2, G. Filauro1

1 Foster Wheeler Environmental Italy2 Eni Agip - Divisione Esplorazione e Produzione

Eni Divisione Esplorazione e ProduzioneAgip

BACKGROUNDThe Incident

• Crude oil well blow-out occurred on February ‘94

• Approximately 12,600 m3 of light sweet crude, 1,000,000 m3 of natural gas and 1,000 m3 of water released to the environment

• Most of the volatile and soluble hydrocarbons flashed during blow-out

• Deposited over 5-Km2 of intensely cultivated agricultural lands

• Deposition influenced by prevailing wind direction to south and south west


BACKGROUND

• A large portion of the oil was retained on and in sandy silt surficial unit to 50 cm

• Vertical migration to subsoil and water table occurred through the sandy gravel subsurface and through infiltration pits used in rice irrigation

• Seasonal fluctuation of the water table level (about 5 m) due to irrigation

• Blow-out occurred when water table was low

• Ground water not used for human consumption


Trecate 24 Well Blow-Out Eni Divisione Esplorazione e Produzione

Agip

Crude Oil Fall-OutEni Divisione Esplorazione e Produzione

Agip

EMERGENCY RESPONSE

• Containment of oily areas and spreading prevention

• 9,350 m3 of free oil were recovered using pumping and vacuum trucks

• Clean-up of the irrigation network

• Clean-up of the Trecate town


EMERGENCY RESPONSEOil recovery from impacted fields


MONITORING PLAN

SOIL220 sampling pointsFrequency: every 3 months

SURFACE WATER27 sampling pointsFrequency: monthly

GROUNDWATER30 sampling pointsFrequency: monthly

AIR8 stations (reduced to 4 after 3 months)Frequency: continuos

BIOLOGICAL EFFECTS- Plants- WildlifeFrequency: 2 campaigns per year


REMEDIATION STRATEGYEnvironmental Constraint

• Authorities and farmers associations requested impacted soil to be remediated without altering or changing its agricultural and biological properties

Bioremediation was selected as remediation approachBioremediation was selected as remediation approach


REMEDIATION STRATEGYSurficial Soil


ZONE 1 - Surface 700 haTPH < 50 ppmMonitoring - Normal AgriculturalOperations w/out Harvesting

ZONE 2 - Surface 480 haTPH 50 - 10,000 ppmLandfarming; Repetition frequencydepending upon Pollution degree

ZONE 3 - Surface 40 haTPH > 10,000 ppmIntensive Landfarming.In the most polluted Area (13 ha)Soil Excavation andEx-Situ treatment in biopiles

REMEDIATION STRATEGYSubsurface Soil

• Contaminated vadose zone soil covering 12,5 ha addressed by Bioventing

• Phase-separated hydrocarbons (PSH) floating on the water table addressed by Bioslurping

• Dissolved-phase hydrocarbons addressed by Natural Attenuation


LANDFARMINGResults

• Treated Surface: 1,200 ha

• Treatment Start-up: September 1994

• January 1995: 93 % of land returned to agriculture

• January 1998: 1,175 ha returned to agriculture (98 % of the initial impacted surface)

• Observed hydrocarbons reduction from concentration greater than 10,000 mg/kg to approx. 50 mg/kg


LANDFARMING ACTIVITIESEni Divisione Esplorazione e Produzione

Agip

BIOPILEConstruction Features

• Two similar Biopiles constructed

• 27,000 m3 of contaminated unbulked soil treated (scraped from 13 ha)

• 20 % by volume of bulking agent added

• Dimensions 50-m x 150-m x 3-m

• 132 internal monitoring locations each Biopile

• Approximately 100 multi-depth soil sampling locations each Biopile


BIOPILE - Isometric

Meters

APPROXIMATE GRAPHIC SCALE

0 5 10 15 20 25

TYPICAL CONFIGURATION OF 0.55m LEVEL







BIOPILEConstruction Activities


BIOPILEConstruction Activities


BIO

PILE

Average P

rocess C

ontrol Data S

umm

ary

0 10 20 30 40 50 60nov-95

dic-95

gen-96

feb-96

mar-96

apr-96

mag-96

giu-96

lug-96

ago-96

set-96

ott-96

nov-96

dic-96

gen-97

feb-97

mar-97

apr-97

mag-97

giu-97

lug-97

DA

TE

TEMPERATURE (c) / MOISTURE (centibars)

0 2 4 6 8 10 12 14 16 18 20

ST

AR

TU

P

OXYGEN (%)

TE

MP

ER

AT

UR

E (C

)

MO

IST

UR

E (ce

ntiba

rs)

OX

YG

EN

(%)

Eni

Divisio

ne E

splo

razion

ee

Pro

du

zion

eA

gip

BIOPILEOperation and Maintenance

• Remediation performance controlled through laboratory analysis of soil samples (quarterly) and through soil gas respiration testing (monthly)

• Air, water, nutrients and heat added where needed (on zone - lift specific basis)

• Continuos and automatic process data management


BIOPILEResults

• Treatment Start-up: November 1995

• Original average TPH concentration in soil: 20,000 mg/kg

• After 18 months residual hydrocarbon content in soil around 5 % of original concentration (resolved compounds)

• Significant total PAH reduction (up to 4-rings)

• Authorities agreed to redistributing treated soil on fields of provenance


BIOPILETPH Reduction

B IO P IL E 1 T P H C O N C E N T R A T IO N (m g /K g )

0

2 00 0

4 00 0

6 00 0

8 00 0

10 00 0

12 00 0

14 00 0

16 00 0

18 00 0

20 00 0

-1 0 1 2 3 4 5 6

Q U A R T E R O F O P E R A T IO N

HY

DR

OC

AR

BO

N C

ON

CE

NT

RA

TIO

N

(mg

/Kg

)

T P H re s o lv e d u n re s o lv e dTPH FITTED RES O L V ED FITTED UNRES O L V ED FITTED

A S Y MPTO TE TPH = 5 8 6 2 A S Y MPTO TE RES O L V ED = 8 4 8 A S Y MPTO TE UNRES O L V ED = 5 0 1 2

P re -B a se l in e

PRETREATMENT


BIOPILEPAH Reduction

B IO P IL E 1 P A H C O N C E N T R A T IO N (m g /K g )

0

10

20

30

40

50

60

70

80

90

100

110

0 1 2 3 4 5 6

Q U A R T E R O F O P E R A T IO N

To

tal P

AH

CO

NC

EN

TR

AT

ION

(mg

/Kg

)

M E AS U R E D C O N C E N T R AT IO N

F IT T E D C O NC E NT R AT IO NS

AS YMP T O T E = 27 .73 ppm


BIOVENTING

• Pilot test performed in two locations to design full-scale system

• Radius of air injection-influence, pressure/airflow relationship and in situ biodegradation rate measured

• Full scale system layout covers 12.5 ha at a depth of approx. 12.5-m


BIOVENTING

• Full scale system includes 26 air injection 4” wells, 5 air injection pumping stations, piping and 36 in situ soil vapor monitoring clusters spaced throughout bioventing area

• Vapour monitoring (O2, CO2 and VHC) and in-situ respiration tests performed on periodic basis


BIOVENTINGResults

• At startup in November 1995 entire area devoid of oxygen (less than 5%) and initial average estimated biodegradation rate approx. 5 mg/kg-soil/day

• Within two weeks of air injection oxygen concentrations increased to 10-20%

• Biodegradation rates in highly impacted areas have increased over time during 1996 and 1997, some as high as 80 mg/kg-soil/day


BIOVENTING Results

• Increase in rates probably a function of enhanced microbial acclimation and relatively new release

• Oxygen demand varies significantly with patchy crude oil subsurface distribution

• System is still running and a reduction of thebiovented area is foreseen in 1998 (almost 30% of original area)


BIOVENTINGAir injection pumping station


PSH RECOVERY• PSH found to float on top of water table during

minimum level period (November through March)

• Approx. 400 m3 of PSH estimated initially

• Pilot test performed to evaluate oil recovery options (skimming, vacuum enhanced pumping and Bioslurping)

• Vacuum enhanced recovery system adopted and built


PSH RECOVERY

• Full scale system covers 3 ha and includes 1 vacuum source and 6 extraction wells equipped with downhole pumps

• System is running only during minimum water table level when PSH are recoverable

• Mobile equipment (Bioslurper) is used when needed


NATURAL ATTENUATION• Dissolved phase hydrocarbon plume was found

as a result of PSH distribution

• Groundwater monitoring network ofpiezometers was designed and built across area of interest

• A protocol for monitoring intrinsic bioremediation implemented (sampling and analysis plan)

• Indicator parameters selected


NATURAL ATTENUATIONResults

• Dissolved oxygen, nitrates, nitrites, sulfate, ferrous iron, methane, alkalinity, oxidation-reduction potential, pH and conductivity monthly monitored over a two year period

• Good relationship between dissolved hydrocarbon plume and intrinsic parameters distribution observed

• No detectable dissolved phase plume observed in downgrading sentinel wells


NATURAL ATTENUATIONResults

• Dissolved hydrocarbon plume appears to be stable, not expanding and intrinsically controlled via aerobic and anaerobic bacterial degradation

• Modeling of the phenomenon using BIO F&T is currently carried out


CONCLUSIONS• Soil, Subsoil and groundwater were impacted as a

consequence of the blow-out

• Use of conventional remediation methods (i.e.. soil excavation and disposal in landfill, water pump & treat, ect.) would have involved:

�extremely large soil movements�change of soil characteristics for agriculture�overall costs higher than bioremediation�heavier environmental impact


CONCLUSIONS

• Use of an integrated bioremediation approach after 4 years has lead to the reclamation of the original impacted area

• Complete release of the area appears possible based on Risk Assessment approach which is being negotiated with the Authorities


Related Papers presented at the Fourth International In Situ and On Site Bioremediation

Symposium (New Orleans, 1997)

• Comparison of Biopile Respiration Rates and Observed Reductions in Soil TPH Concentration (H.J.(H.J. ReisingerReisinger and others)and others)

• Demonstrated Cost Effectiveness of Bioventing at a Large Crude-Oil Impacted Site (H.J.(H.J. ReisingerReisinger and others)and others)

• Natural Attenuation of a Petroleum Production Well Release in Northern Italy (C.D.(C.D. FintonFinton and others)and others)

• Degradation of Saturated and Polycyclic Aromatic Hydrocarbons and Formation of Their Metabolities in Bioremediated Crude Oil-Containing Soil (A.(A. PortaPorta and others)and others)

• Evaluation of Optimum Hydrocarbon Degradation Conditions: ABiotreatability Study (D.(D. TamburiniTamburini and others)and others)


Documents

1 Foster Wheeler Environmental Italy Eni Agip - Divisione ...dorsogna/byron/Trecate.pdf · blow out of trecate 24 crude oil well: how bioremediation techniques are solving a major