1. FMC SPILL SITE July 11, 1996: Tanker truck turned over spilling 6000 gallons (23000L) gasoline 500ft (150m) North from Bear Creek Emergency Response Team observed no standing gasoline, rapid infiltration The ERT was unable to locate subsurface free product History CLUBB, MISSOURI, USA

2. FMC SPILL SITE Overturned Tanker Truck

3. FMC SPILL SITE 10ft (3m) dry silty sand top layer, 10ft (3m) wet sandy clay with gravel underneath Porosity ~0.4 Conductivity ~85ft/d (26m/d) Aquifer thickness ~20ft (6m) Groundwater surface ~7ft (2m) below ground surface Gradient estimated to be 0.0174 towards the southeast Site Geology

4. FMC SPILL SITE

5. Truck Location Spill Site

6. FMC SPILL SITE Contractor #1 (07/96) –Geoprobed site to identify location of free product (07/96) –Installed 4 monitoring wells –Suggested air-sparging system (State did not approve) –State noticed drillers were not licensed, equipment not registered (08/96) Chronology of events (1996)

7. FMC SPILL SITE

8. FMC –Geoprobed site, found 6 (15cm) free product along the north and south side of highway (08/96) –Installed an interceptor trench south of the highway –Recovered free product from trench (09/96) Chronology of events (1996)

9. FMC SPILL SITE Interceptor Trench Construction

10. FMC SPILL SITE Interceptor Trench Construction

11. FMC SPILL SITE Interceptor Trench Construction

12. FMC SPILL SITE Contractor #2 (09/96) –Geoprobed site to locate free product and plume (10/96) –Free product plume about 400ft (120m) long and 100ft (30m) wide –Pump test showed tranmissivities ranging 1100- 2000 ft 2 /d (100-186 m 2 /d) –Estimated conductivity was 85ft/d (26m/d) Interceptor trench showed 3" (8cm) free product (10/96) Chronology of events (1996)

13. FMC SPILL SITE High levels of BTEX migrated to the stream

14. FMC SPILL SITE Contractor #2 (Cont.) –Installed 5 remediation wells, depth around 24ft (7m) inside interceptor trench (11/96) –Manual operation of free product recovery system started in January 1997 –Remediation system running 24h/d halfway March 1997 –Pumping rates ~18 GPM (68 L/min), creating drawdowns of ~15ft (4.5m) Chronology of events (96/97)

15. FMC SPILL SITE

17. Contractor #2 (Cont.) –Never got more than 100 gallons (378 L) of free product from recovery system (07/97) –Contractor terminated in 07/97 Contractor #3 (07/97) –Unable to continue with existing system, remediation 3 weeks down. –2 MWs showed 19 (48cm) free product –Dual Phase extraction system operative (04/98) Chronology of events (97/98)

18. FMC SPILL SITE Overall Pump & Treat System

19. FMC SPILL SITE

21. Poor handling of NAPL issue –Overpumping causing high drawdowns created smear zone –Needed more monitor wells downgradient –Expensive remediation (Cadillac) system but poorly designed and missing target NAPL zone Soil strata poorly defined Initial response contractors inappropriate and too slow Failed System

22. FMC SPILL SITE Dual Phase Vacuum Extraction