Document Overview
This case history summarizes a documented PES-51 shoreline treatment demonstration associated with residual Exxon Valdez oil in Prince William Sound, Alaska. The 1995 workshop report was prepared for the Exxon Valdez Oil Spill Restoration Project by the Alaska Department of Environmental Conservation in cooperation with residents of Chenega Bay. The report describes remaining surface and subsurface oil near Chenega Bay, the evaluation of additional shoreline treatment options, and a PES shoreline treatment process using PES-51, airknife injection, ambient seawater flushing, boom containment, skimming, and sorbent recovery.
Reported Remediation Results
| Metric | Before / Initial | After / Final | Reported Change | Notes |
|---|---|---|---|---|
| Treatment area | Residual surface and subsurface Exxon Valdez oil remained in shoreline sediments near Chenega Bay. | 120 ft × 135 ft Sleepy Bay demonstration area | Documented field demonstration area | The workshop report states that the 1993 demonstration used the PES technique on a 120 ft × 135 ft area at Sleepy Bay near Chenega Bay. |
| PES-51 used | PES shoreline treatment process applied to residual shoreline oil. | 165 gallons of PES-51 used | Reported treatment input | The report states that test results indicated 165 gallons of PES-51 were used during the Sleepy Bay demonstration. |
| Oily liquids recovered | Oil-water mixture emerged during PES-51 injection and flushing. | 120 gallons of oily liquids recovered | Recovered using skimmer and absorbent materials | The report states that 120 gallons of oily liquids were recovered using the skimmer and a variety of absorbent materials. |
| Subsurface petroleum hydrocarbon reduction | Residual subsurface oil in shoreline sediment | Immediate 70% decrease; greater than 90% decrease one year later | Reported semivolatile-range total petroleum hydrocarbon reduction | Appendix E reports an immediate 70% decrease in semivolatile-range total petroleum hydrocarbons in subsurface sediment and a decrease exceeding 90% in samples obtained one year later. |
| Water-column observation | Treatment involved shoreline flushing and recovery. | No oil present in water tests; no detectable petroleum hydrocarbons introduced into the water column | Reported water-column protection result | The report states tests indicated no oil was present in the water; Appendix E states improvements were achieved without introducing detectable petroleum hydrocarbons into the water column along the shoreline below the treatment area. |
| Treatment-method fit | Residual oil remained after prior cleanup methods from 1989 to 1992. | PES-51 with airknife injection, flushing, containment, skimming, and sorbent recovery | Site-specific treatment approach | The report says the Sleepy Bay site had previously been subjected to multiple cleanup methods, and that PES-51 and the airknife technique were useful but not a universal solution. |
Project and Application Details
PES Application Summary
The PES shoreline treatment process used an airknife injection system to penetrate and dilate subsurface shoreline sediment and apply PES-51 to displace oil from surface and subsurface materials. The report describes PES-51 as reducing the interfacial tension between petroleum hydrocarbons and surfaces, releasing oil onto water used to flush it away. Released oil was flushed toward a double-boomed shoreline recovery area using ambient-temperature seawater, then collected with skimmers, storage tanks, and sorbent materials. The report states that the displaced oil was not chemically altered or emulsified, but floated on the water surface where it could be collected and recovered.
Reported Outcome
The report states that the 1993 Sleepy Bay demonstration used 165 gallons of PES-51 and recovered 120 gallons of oily liquids using a skimmer and absorbent materials. It also states that tests indicated no oil was present in the water and that treatment goals were met. The PES cost-estimate appendix describes a visible decrease in subsurface oil residue, approximately 100 gallons of oily liquid recovered, an immediate 70% decrease in semivolatile-range total petroleum hydrocarbons in subsurface sediment, and a decrease exceeding 90% in sediment samples obtained one year later.
Key Takeaways
PES-51 was referenced in an Exxon Valdez Oil Spill Restoration Project workshop report addressing residual shoreline oil near Chenega Bay.
The report describes PES-51 as the shoreline cleaning agent that appeared to meet NOAA criteria, appeared effective on both surface and subsurface oil, and could be removed from the water during treatment.
The Sleepy Bay demonstration combined PES-51 application with airknife injection, ambient seawater flushing, double-boom containment, skimmer recovery, and sorbent recovery.
The treatment approach emphasized release, flotation, containment, and recovery of oil rather than chemical emulsification or dispersion.
The report cautions that PES-51 was not a universal solution and that each beach should be evaluated separately to determine the appropriate treatment method.
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