August xx, 2012

Public comment draft Staff Report recommending No Further Action.

DEQ Staff Report: Taxiway T Fuel Hydrant Characterization and Cleanup. ECSI

DEQ has reviewed the referenced reports and has concluded that conditionally, no further action is required in the investigation and remediation of the Taxiway T jet fuel hydrant D-H21, west of Concourse D. The condition is that residual jet fuel remains in site soils near jet fuel hydrant D-H21 and a Contaminated Media Management Plan (CMMP) must be prepared to protect future excavation and construction workers and to direct appropriate disposal of contaminated soil and groundwater.

DEQ has the following summary and conclusions:

An unknown amount of jet fuel was released to subsurface soils from a misaligned gasket at the base of the sub-grade fuel hydrant spill bucket. The release was discovered during subsurface investigation work to characterize the fuel distribution system in this part of the airport. Remediation work consisted of removal of the fuel hydrant and spill bucket and excavation and off-site disposal of 77 tons of petroleum-contaminated soil. Excavation work removed sandy fill soils and was stopped at approximately 8 feet, at the upper contact of native silty soil. Groundwater was observed in the excavation and presented petroleum sheen but no measureable product thickness. Confirmation soil samples were reportedly collected from the base of the excavation and submitted for laboratory analysis. One of the four samples exceeded risk-based criteria for diesel-range petroleum for a construction worker pathway scenario. This soil remains in-place beneath the later fuel pipeline east of fuel hydrant D-H21.

The vertical extent of contamination appears to be at approximately 8 feet, at the water table. The lateral extent of contaminant has been determined using data from soil samples. The north, south and west sides of the remedial excavation were found to contain residual jet fuel at low concentrations (<1000 ppm), well below the acceptable risk standard for construction and excavation workers of 23,000 ppm for diesel and jet fuels. To the east, the jet fuel has travelled a short distance along the pipeline that feeds the fuel hydrant. The lateral extent of jet fuel migration to the east extends beyond the remedial excavation but less than 10 feet from the hydrant. This lateral extent determination was based on data from a soil boring drilled next to the pipeline ten feet from the hydrant which did not detect any petroleum hydrocarbons.

DEQ has determined that no further action is necessary at fuel hydrant D-H21 at this time based on no residual contamination values from spilled jet fuel in excess of applicable risk standards to aircraft maintenance workers. DEQ recommends that a CMMP be prepared to advise potential future excavation and site construction workers who may encounter potentially unsafe soil contaminant levels near fuel hydrant D-H21. The CMMP will also provide information on appropriate disposal requirements for excavated soil from the immediate vicinity of fuel hydrant D-H21.

Please do not hesitate to call me with questions at 503 229-6015.

Sincerely,

Kenneth Thiessen, CEG

References reviewed and cited:

March 16, 2007, Taxiway T and Terminal Apron Rehabilitation – Phase II: Subsurface Investigation Results, Portland International Airport. Ash Creek Associates, Inc. project 1168-01

July 24, 2007, Taxiway T and Terminal Apron Rehabilitation – Phase I Technical Assistance, Portland International Airport. Ash Creek Associates, Inc. project 1168-01

January 31, 2008, Groundwater Investigation Results, Taxiway T and Terminal Apron Rehabilitation, 7000 NE Airport Way Portland, Oregon, Ash Creek Associates, Inc. project 1168-01