BLOW OUT OF TRECATE 24 CRUDE OIL WELL: HOW BIOREMEDIATION TECHNIQUES ARE SOLVING A MAJOR ENVIRONMENTAL EMERGENCY IN A VALUABLE AGRICULTURAL AREA

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1 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. Arlotti 1, G. Andreotti 2, G. Filauro 1 1 Foster Wheeler Environmental Italy 2 Eni Agip - Divisione Esplorazione e Produzione Agip

2 BACKGROUND The Incident Crude oil well blow-out occurred on February 94 Approximately 12,600 m 3 of light sweet crude, 1,000,000 m 3 of natural gas and 1,000 m 3 of water released to the environment Most of the volatile and soluble hydrocarbons flashed during blow-out Deposited over 5-Km 2 of intensely cultivated agricultural lands Deposition influenced by prevailing wind direction to south and south west

3 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

4 Trecate 24 Well Blow-Out

5 Crude Oil Fall-Out

6 EMERGENCY RESPONSE Containment of oily areas and spreading prevention 9,350 m 3 of free oil were recovered using pumping and vacuum trucks Clean-up of the irrigation network Clean-up of the Trecate town

7 EMERGENCY RESPONSE Oil recovery from impacted fields

8 MONITORING PLAN SOIL 220 sampling points Frequency: every 3 months SURFACE WATER 27 sampling points Frequency: monthly GROUNDWATER 30 sampling points Frequency: monthly AIR 8 stations (reduced to 4 after 3 months) Frequency: continuos BIOLOGICAL EFFECTS - Plants - Wildlife Frequency: 2 campaigns per year

9 REMEDIATION STRATEGY Environmental 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 approach

10 REMEDIATION STRATEGY Surficial Soil ZONE 1 - Surface 700 ha TPH < 50 ppm Monitoring - Normal Agricultural Operations w/out Harvesting ZONE 2 - Surface 480 ha TPH 50-10,000 ppm Landfarming; Repetition frequency depending upon Pollution degree ZONE 3 - Surface 40 ha TPH > 10,000 ppm Intensive Landfarming. In the most polluted Area (13 ha) Soil Excavation and Ex-Situ treatment in biopiles

11 REMEDIATION STRATEGY Subsurface 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

12 LANDFARMING Results 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

13 LANDFARMING ACTIVITIES

14 BIOPILE Construction 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

15 BIOPILE - Isometric TYPICAL CONFIGURATION OF 3.30m LEVEL TYPICAL CONFIGURATION OF 2.75m LEVEL TYPICAL CONFIGURATION OF 2.20m LEVEL TYPICAL CONFIGURATION OF 1.65m LEVEL TYPICAL CONFIGURATION OF 1.10m LEVEL TYPICAL CONFIGURATION OF 0.55m LEVEL Meters APPROXIMATE GRAPHIC SCALE

16 BIOPILE Construction Activities

17 BIOPILE Construction Activities

18 Eni Divisione Agip Esplorazione e Produzione BIOPILE Average Process Control Data Summary nov-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 TEMPERATURE (c) / MOISTURE (centibars) OXYGEN (%) TEMPERATURE (C) MOISTURE (centibars) OXYGEN (%) STARTUP DATE

19 BIOPILE Operation 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

20 BIOPILE Results 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

21 BIOPILE TPH Reduction HYDROCARBON CONCENTRATION (mg/kg) 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 ) P R E T R E A T M E N T P re -B a se l i n e Q U A R T E R O F O P E R A T IO N T P H re s o lv e d u n re s o lv e d TPH FITTED RES O L V ED FITTED UNRES O L V ED FITTED A S Y MPTO TE TPH = A S Y M PTO TE RES O L V ED = A S Y MPTO TE UNRES O L V ED =

22 BIOPILE PAH Reduction Total PAH CONCENTRATION (mg/kg) 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 ) 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 N C E N T R AT IO N S AS YMP T O T E = ppm Q U A R T E R O F O P E R A T IO N

23 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 m

24 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 (O 2, CO 2 and VHC) and insitu respiration tests performed on periodic basis

25 BIOVENTING Results 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

26 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 the biovented area is foreseen in 1998 (almost 30% of original area)

27 BIOVENTING Air injection pumping station

28 PSH RECOVERY PSH found to float on top of water table during minimum level period (November through March) Approx. 400 m 3 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

29 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

30 NATURAL ATTENUATION Dissolved phase hydrocarbon plume was found as a result of PSH distribution Groundwater monitoring network of piezometers was designed and built across area of interest A protocol for monitoring intrinsic bioremediation implemented (sampling and analysis plan) Indicator parameters selected

31 NATURAL ATTENUATION Results Dissolved oxygen, nitrates, nitrites, sulfate, ferrous iron, methane, alkalinity, oxidationreduction 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

32 NATURAL ATTENUATION Results 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

33 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

34 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

35 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. Reisinger and others) Demonstrated Cost Effectiveness of Bioventing at a Large Crude- Oil Impacted Site (H.J. Reisinger and others) Natural Attenuation of a Petroleum Production Well Release in Northern Italy (C.D. Finton and others) Degradation of Saturated and Polycyclic Aromatic Hydrocarbons and Formation of Their Metabolities in Bioremediated Crude Oil- Containing Soil (A. Porta and others) Evaluation of Optimum Hydrocarbon Degradation Conditions: A Biotreatability Study (D. Tamburini and others)