Final Hydraulic Oil Line Leak Site Investigation Report United Airlines Ground Support Equipment Maintenance Facility Seattle Tacoma International Airport Seattle, Washington Prepared for: United Airlines 1200 East Algonquin Road Elk Grove Village, Illinois 60007 November 2009 www.erm.com Delivering sustainable solutions in a more competitive world
76
Embed
Final Hydraulic Oil Line Leak Site Investigation Report
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Final Hydraulic Oil Line Leak Site Investigation Report United Airlines Ground Support Equipment Maintenance Facility Seattle Tacoma International Airport Seattle, Washington
Prepared for: United Airlines 1200 East Algonquin Road Elk Grove Village, Illinois 60007
November 2009
www.erm.com
Delivering sustainable solutions in a more competitive world
United Airlines
Final Hydraulic Oil Line Leak Site Investigation Report United Airlines Ground Support Equipment Maintenance Facility, Seattle Tacoma International Airport, Seattle, Washington
November 2009
Project No. 0099081
A. Michael Arnold, RG Project Manager
James Warner, PG Partner in Charge
ERM-West, Inc. 915 118th Avenue Southeast, Suite 130 Bellevue, Washington 98005 T: 425-462-8591 F: 425-455-3573
FINAL
i
TABLE OF CONTENTS
LIST OF FIGURES iii
LIST OF TABLES iii
LIST OF ACRONYMS iv
EXECUTIVE SUMMARY ES-1
1.0 INTRODUCTION 1
1.1 SITE BACKGROUND 1
1.2 SCOPE OF WORK AND OBJECTIVES 2
1.3 REGULATORY OVERVIEW 3
2.0 INVESTIGATION PROCEDURES 5
2.1 FIELD PREPARATION 5
2.2 CONTAMINATED SOIL REMOVAL 5
2.3 SOIL INVESTIGATION 6
2.4 INVESTIGATION-DERIVED WASTE MANAGEMENT 7
3.0 SOIL INVESTIGATION RESULTS 8
3.1 SOIL AND GROUNDWATER CONDITIONS 8
3.2 FIELD SCREENING RESULTS 8
3.3 SOIL ANALYTICAL RESULTS AND DISCUSSION 8
3.4 TERRESTRIAL ECOLOGICAL EVALUATION 9
4.0 CONCLUSIONS AND RECOMMENDATIONS 11
4.1 CONCLUSIONS 11
FINAL
ii
4.2 RECOMMENDATIONS 11
5.0 REFERENCES 12
APPENDIX A — SITE PHOTOGRAPHS
APPENDIX B — HYDRAULIC OIL MATERIAL SAFETY DATA SHEET
APPENDIX C — BORING LOGS
APPENDIX D — WASTE MANIFEST
APPENDIX E — ANALYTICAL LABORATORY DATA REPORTS
APPENDIX F — TERRESTRIAL ECOLOGICAL EVALUATION – EXPOSURE ANALYSIS PROCEDURE FORM
FINAL
iii
LIST OF FIGURES
(Figures immediately follow the text)
Figure 1 Site Location Map
Figure 2 Site Vicinity
Figure 3 Soil Sample and Boring Locations
Figure 4 Cross Section A-A’
Figure 5 Petroleum Hydrocarbons in Soil
LIST OF TABLES
(Tables immediately follow the figures)
Table 1 Summary of Petroleum Hydrocarbons Detected in Soil
Table 2 Summary of Extractable Petroleum Hydrocarbons in Soil
FINAL
iv
LIST OF ACRONYMS
bgs below ground surface
Ecology State of Washington Department of Ecology
EPH extractable petroleum hydrocarbons
ERM ERM-West, Inc.
DMSO dimethyl sulfoxide
GSE Ground support equipment
MTCA Model Toxics Control Act Cleanup Regulation
NFA No Further Action
PID photoionization detector
TPH-D diesel- heavy oil-range total petroleum hydrocarbon
TPH-HO diesel- heavy oil-range total petroleum hydrocarbons
UAL United Airlines
VCP Voluntary Cleanup Program
WAC Washington Administrative Code
FINAL
ERM ES-1 UAL/0099081/NOVEMBER 2009
EXECUTIVE SUMMARY
This report has been prepared by ERM-West, Inc. (ERM) on behalf of United Airlines (UAL) to present soil data for the hydraulic oil line leak at the UAL ground support equipment maintenance facility at the Seattle-Tacoma International Airport (SEA). This report is being submitted to the State of Washington Department of Ecology (Ecology) to document site conditions in compliance with the Model Toxics Control Act Cleanup Regulation (MTCA) and to obtain regulator concurrence for the conclusions regarding site characterization and the recommended remediation alternative for petroleum hydrocarbons in the subsurface.
The hydraulic oil leak was suspected by UAL personnel in February 2009 after it was discovered that the reservoir serving the three hydraulic vehicle lifts in the facility had lost fluid, resulting in impaired performance of the lifts. Subsequent testing identified the leak at a loose fitting in the sub-slab piping serving one of the lifts. The leak was repaired and the system tightness tested prior to placing the system back into service in July 2009.
The soil conditions in the vicinity of the hydraulic line leak were investigated on 30 June and 1 July 2009. The results of the investigation indicate that soils with concentrations of petroleum-related hydrocarbons greater than applicable Model Toxics Control Act Method A Cleanup Standards for Unrestricted Land Uses (i.e., the mineral oil standard of 4,000 milligrams per kilogram) are limited to soils less than 15 feet below ground surface in the immediate vicinity of the release. Based on the limited area of contamination, and the known depth to groundwater in the vicinity (approximately 90 feet below ground surface) documented during other investigations, impact to groundwater quality related to this release is unlikely. During the investigation, approximately 5 cubic feet of petroleum-impacted soil was removed from the release area using a vacuum truck equipped with an air knife.
It is ERM’s opinion that the investigation has generated sufficient data to characterize site conditions including an evaluation of potential impacts to groundwater from the leak. The volume of impacted soil and nature of the contaminant present (mineral oil) suggest that excavation an off-site treatment or disposal is an appropriate presumptive remedial measure. Due to the presence of active operations critical to UAL’s SEA operations in the building present over the release, the structural considerations involved in removing the impacted soil, and the lack of complete
FINAL
ERM ES-2 UAL/0099081/NOVEMBER 2009
exposure pathways for the existing contamination, ERM recommends that remedial action be postponed until building demolition or renovation provides an opportunity to access and remove the soils.
FINAL
ERM 1 UAL/0099081/NOVEMBER 2009
1.0 INTRODUCTION
This report has been prepared by ERM-West, Inc. (ERM) on behalf of United Airlines (UAL) to present soil and groundwater investigation data for the UAL Ground Support Equipment (GSE) maintenance facility at Seattle-Tacoma International Airport in Seattle, Washington (the “site”) (Figure 1). The investigation was completed to address hydraulic oil that leaked from a subsurface line serving a hydraulic vehicle lift in the UAL Ground Support Equipment (GSE) maintenance facility. This report is being submitted to the State of Washington Department of Ecology (Ecology) to document site conditions in compliance with the Model Toxics Control Act Cleanup Regulation (MTCA) (Chapter 173-340 Washington Administrative Code [WAC]) and to obtain regulator concurrence for the conclusions regarding site characterization and the recommended remediation alternative for petroleum hydrocarbons in the subsurface. It is anticipated that the data presented in this report will be sufficient to support a No Further Action (NFA) determination by Ecology within the Voluntary Cleanup Program (VCP), conditional upon completion of remediation that would be postponed until site conditions are amenable to removal of the hydraulic oil-impacted soil present.
1.1 SITE BACKGROUND
The site location is shown on Figures 1 and 2, and a site plan is included as Figure 3. ERM understands that in early 2009, UAL employees noticed a loss of hydraulic pressure in the hydraulic system in February 2009, which was traced to a low fluid level in the hydraulic oil reservoir tank. Since the tank had previously been full, UAL personnel suspected a leak in the system. A leak was confirmed as a result of testing, and the release was reported to Ecology by UAL personnel in February 2009 via telephone conversation. Photographs of the release area are included in Appendix A.
The hydraulic lift system at the UAL GSE Maintenance facility consists of an above-ground hydraulic oil reservoir (approximately 250-gallon capacity) serving two single-ram lifts and one double-ram lift. The Material Safety Data Sheet for the hydraulic oil (Appendix B) indicates that the mixture is greater than 97% mineral oil, with less than 3% dimethyl sulfoxide (DMSO). One pressure line serves the reservoir to both single-ram lifts, and another line serves the double-ram lift. During a site visit completed by ERM on 27 February 2009, UAL personnel
FINAL
ERM 2 UAL/0099081/NOVEMBER 2009
indicated that the hydraulic system had lost a significant portion of the reservoir volume, which was discovered when sufficient hydraulic pressure could not be achieved during an attempt to use each of the three hydraulic lifts at the same time.
Subsequent pressure testing of the line indicated that the pressurized hydraulic line between the reservoir and the two single-ram lifts was leaking. UAL personnel reported the potential release of hydraulic oil to the subsurface to Ecology in late February 2009. Upon identification of the pressure loss, UAL personnel turned off valves to isolate the failed line and disconnected the line at the reservoir. Each of the three hydraulic lifts remained out of service until leak detection, line repair, and system tightness testing were completed in June and July 2009.
UAL retained Pacific West Contractors, Inc., (Pacific West) to test the hydraulic oil line for leakage and expose and repair the line. Pacific West used helium gas and helium detectors to identify the leak and sawed the concrete to expose the leaking section (Figure 3). The leak was traced to a loosely-threaded fitting in the hydraulic oil line. Pacific West repaired the leak and pressure-tested the hydraulic line before it was returned to service In July 2009.
The hydraulic lift system and investigation area are contained completely within a building at the site. The building is surrounded by paved aircraft operations area and parking areas, with only minor unpaved planting strips present. Surface water from the building roof and surroundings is discharged to the airport stormwater collection system.
1.2 SCOPE OF WORK AND OBJECTIVES
The scope of work completed during the site investigation included the following tasks:
• Observe hydraulic line excavation efforts and screen soils removed from the excavation for the presence of petroleum hydrocarbons;
• Collect two soil samples from the hydraulic line repair excavation and analyze the soil samples for diesel- heavy oil-range total petroleum hydrocarbons (TPH-D and TPH-HO) using Ecology Method MWTPH-Dx;
• Complete five soil borings to depths ranging from 23 to 30 feet below ground surface (bgs) (estimated depth to bottom of glacial till unit) to evaluate the horizontal and vertical extent of petroleum impacts;
FINAL
ERM 3 UAL/0099081/NOVEMBER 2009
• Collect 15 total soil samples from the borings for analysis of TPH-D and TPH-HO using Ecology Method MWTPH-Dx; and
• Complete appropriate containment, transport and disposal of the petroleum-contaminated soil.
The objectives of the site investigation and this report are to:
• Document the nature and extent of subsurface petroleum-related impacts in the vicinity of the hydraulic lift system;
• Compare the site soil conditions to the appropriate MTCA regulatory cleanup standards and site characterization requirements; and
• Document the site investigation results to establish compliance with the MTCA regulation and support an NFA determination from Ecology within the VCP.
1.3 REGULATORY OVERVIEW
The MTCA, Chapter 173-340 WAC provides the regulatory framework for evaluating and establishing compliance for site contamination associated with the hydraulic oil release. This report is intended to meet MTCA site characterization requirements, and to provide appropriate remedial recommendations to support a conditional NFA from the Ecology VCP.
MTCA provides a regulatory framework for investigation and remediation of contaminated media. While the regulation is developed to define the procedures required for investigation and cleanup completed under formal consent decrees or agreed orders, the Ecology VCP provides review of independent actions completed in substantive compliance with MTCA. The site investigation outlined in this report is an independent action completed in this manner. Through the VCP, Ecology can issue opinions and NFA determinations for sites compliant with MTCA requirements.
Based on the MTCA compliance pathway summarized above, cleanup standards are developed to evaluate whether contaminant concentrations at a particular site are compliant with the regulation. The MTCA regulation provides three levels of cleanup standard development for contaminated sites: Methods A, B, and C. MTCA Method A cleanup levels are conservative lookup levels with broad applicability as outlined in Chapter 173-340-704 WAC. MTCA Method B includes calculated risk-based cleanup standards that have broad applicability, including non-industrial sites (Chapter 173-340-705 WAC). MTCA Method C cleanup
FINAL
ERM 4 UAL/0099081/NOVEMBER 2009
levels are risk-based calculated standards applicable only to industrial sites meeting a limited set of requirements as described in Chapter 173-340-706 WAC. MTCA Methods B and C can be used to evaluate compliance of multiple hazardous substances and pathways, and both may be applied by using default assumptions in MTCA or by using site-specific data.
The MTCA regulation outlines the site requirements for applicability of Method A for soil and groundwater impacts in Chapters 173-340-704, 720, and 740 WAC. The conditions of the site meet the criteria for the application of Method A, and is therefore eligible for establishment of MTCA Method A cleanup standards for the hydraulic oil. The MTCA Method A Cleanup Level for Unrestricted Land Use for mineral oil is 4,000 milligrams per kilogram (mg/kg). There is no established Federal or Washington State cleanup standard for DMSO, the additive reported on the Material Safety Data Sheet (Appendix A). DMSO is commonly prescribed for topical application and ingestion as a medicinal agent, and is not considered a toxin. Based on the nature of the hydraulic oil as described in the Material Safety Data Sheet, it is ERM’s opinion that the MTCA Method A cleanup level for mineral oil (4,000 mg/kg) is the appropriate cleanup standard to apply to the hydraulic oil release.
FINAL
ERM 5 UAL/0099081/NOVEMBER 2009
2.0 INVESTIGATION PROCEDURES
This section includes a discussion of the procedures used during the hydraulic oil release investigation. These activities included field preparation, contaminated soil removal, the soil investigation, and investigation-derived waste management.
2.1 FIELD PREPARATION
ERM performed certain activities in preparation for conducting the field work. ERM prepared a site-specific Health and Safety Plan to be used during the field activities. Boart Longyear of Fife, Washington, and ALS Laboratories of Everett, Washington, were subcontracted to perform the project drilling and laboratory services, respectively. Drilling permits were obtained from Ecology by Boart Longyear. ERM requested a public utility locate through the Washington State Utilities Underground Location Center. On 29 June 2009, prior to commencement of drilling activities, ERM met with public utility representatives to mark any utilities in the proposed work area. In addition, ERM contracted a private utility locate service (APS of North Bend, Washington) to identify utilities not captured by the public locating. Private utility clearance activities were performed on 30 June and 1 July 2009. As a final precautionary measure, a combination of air knife and vacuum excavation was performed by APS at each soil boring location to minimize the risk of striking unidentified underground utilities.
2.2 CONTAMINATED SOIL REMOVAL
On 30 June 2009, ERM directed APS personnel to use the air knife and truck-mounted vacuum system to remove approximately 5 cubic feet of soil from directly beneath the hydraulic oil line leak in the area shown in Figure 3. The soil was placed in labeled, steel 55-gallon drums that were moved to a designated UAL waste storage area pending characterization and disposal. The area available for excavation directly beneath the hydraulic oil leak was constrained laterally by a structural footing to the north and by the enclosure for the subsurface hydraulic lift ram and piping to the south. Soil was removed to a depth of approximately 3 feet bgs.
FINAL
ERM 6 UAL/0099081/NOVEMBER 2009
2.3 SOIL INVESTIGATION
On 10 June 2009, an ERM representative collected two soil samples (S-1 and S-2) from the recently-exposed soils in the vicinity of the hydraulic line break. The soil samples were collected from a depth of approximately 20 inches below grade using a stainless steel trowel ands were submitted to ALS for analysis of TPH-D and TPH-HO by Ecology Method NWTPH-Dx. An additional grab soil sample (GS Hoist Leak) was collected from the same area on 30 June 2009 for analysis of TPH-D and TPH-HO by Ecology Method NWTPH-Dx, and extractable petroleum hydrocarbons (EPH) by Ecology Method EPH. EPH analysis was completed to develop data in the event that a MTCA Method C compliance evaluation was applicable to the site. The sample locations are shown on Figure 3.
On 30 June and 1 July 2009, ERM personnel supervised the advancement of five borings (B-1 through B-5) in the vicinity of the hydraulic line leak to depths ranging from 23 to 30 feet bgs. The borings were drilled using a limited-access sonic drilling rig operated by Boart Longyear. The locations of the borings are indicated on Figure 3. Continuous soil samples were collected to total depth in all of the borings. An ERM geologist logged the soils and completed field screening of soils for the presence of petroleum hydrocarbons. Three soil samples from each boring were submitted to the laboratory for analysis of TPH-D and TPH-HO based on field screening results and relative location of the samples within each boring. Boring logs are included in Appendix C.
Soils from each 5-foot interval were screened for volatile organic vapors using a photoionization detector (PID) by placing a portion of soil from each sample interval into a sealable plastic bag and then placing the PID probe into the bag and recording the meter response. Petroleum sheen screening was also completed for soils at 5-foot intervals by placing a small amount of soil in a pan with water and observing whether a sheen developed. PID response and sheen screening results are included on the boring logs in Appendix C.
Soil samples were collected from each boring at intervals where field screening indicated the highest levels of contamination, and at the bottom of each boring. The soil samples were each analyzed for TPH-D and TPH-HO by Ecology Method NWTPH-Dx.
FINAL
ERM 7 UAL/0099081/NOVEMBER 2009
2.4 INVESTIGATION-DERIVED WASTE MANAGEMENT
Soil and decontamination water generated during site investigation activities were stored in 55-gallon steel drums at the facility pending characterization. The drums were removed for disposal on 29 October 2009 by PSC Environmental Services Group of Seattle, Washington. The waste manifest is included in Appendix D; note that the manifest also includes a shipment of polychlorinated biphenyl-containing waste unrelated to this effort.
FINAL
ERM 8 UAL/0099081/NOVEMBER 2009
3.0 SOIL INVESTIGATION RESULTS
This section describes observations and data developed during the hydraulic oil release investigation.
3.1 SOIL AND GROUNDWATER CONDITIONS
The soils beneath the UAL maintenance facility consisted of sand and gravel to a depth of between 20 and 27 feet bgs, below which, the soils consisted of medium-grained sand. The soils encountered likely represent the upper (sand and gravel) and lower (medium sand) facies of the Esperance sand, which is typically encountered beneath glacial till in the Seattle Tacoma Airport Aircraft Operations Area near the North Satellite and Concourses C and D, south of the site (Enviro-Sciences, Inc. 2002 and ERM 2005). A cross section of soil conditions at the site is shown in Figure 4.
Groundwater was not encountered in any of the borings. Previous investigations in the vicinity indicate that the shallowest groundwater is typically encountered within the Esperance sand below 90 feet bgs (Enviro-Sciences, Inc. 2002, ERM 2005, Aspect Consulting 2005).
3.2 FIELD SCREENING RESULTS
No organic vapors were measured in any of the soil samples during screening with the PID. A sheen suggesting the presence of petroleum product was observed in soil samples collected from each of the borings. Sheen was observed in several soil intervals from borings B-1 and B-3, and throughout the entire soil column in borings B-2, B-4, and B-5.
3.3 SOIL ANALYTICAL RESULTS AND DISCUSSION
Analytical results for TPH-D and TPH-HO analyses of soil samples from the site are summarized in Table 1, and analytical laboratory data reports are included in Appendix E. A summary of soil sample analytical results for TPH-D and TPH-HO are included in Figure 5. TPH-D and TPH-HO were detected in each of the soil samples S-1, S-2, and GS Hoist Leak, which were collected from shallow soils near the hydraulic oil leak. The combined concentrations of TPH-D and TPH-HO in samples S-2 and GS
FINAL
ERM 9 UAL/0099081/NOVEMBER 2009
Hoist Leak were greater than the MTCA Method A cleanup level for mineral oil of 4,000 mg/kg.
TPH-HO was detected at a concentration of 1,200 mg/kg in the soil sample from a depth of 10 feet bgs in boring B-2. Petroleum hydrocarbons were not detected in each of the other 14 soil samples collected from the borings. The concentration detected in boring B-2 is less than the MTCA Method A cleanup level for mineral oil of 4,000 mg/kg.
EPH results for sample GS Hoist Leak are summarized in Table 2, and analytical laboratory data reports are included in Appendix E. Note that MTCA cleanup values are not applicable to EPH results, which were developed in the event a MTCA Method B or C regulatory compliance pathway was considered for the site. EPH results for the sample are consistent with a mineral oil-based product.
Soil sample results indicate that concentrations of petroleum hydrocarbons in excess of applicable cleanup standards are limited to soils in the immediate vicinity of the release, and that release impacts have not significantly migrated vertically or horizontally. The depth of petroleum impacts relative to depth to groundwater (approximately 90 feet bgs) indicate that it is unlikely that material released from the hydraulic line has impacted groundwater quality. Based on the apparent volume released, the current distribution of petroleum hydrocarbons in soil, the location of the release in an area not affected by surface water infiltration, the soil type, and released oil viscosity, it is unlikely that this release will migrate and impact groundwater in the future. Due to the non-volatile nature of the hydraulic oil, vapor intrusion is not a concern associated with this release.
ERM estimates that less than 50 cubic yards of soil with concentrations of petroleum hydrocarbons greater than the applicable MTCA Method A cleanup level are present at the site. Based on the volume of soil present and site conditions, a presumptive remedy of soil excavation with off-site treatment or disposal is recommended. This soil is currently not readily accessible for excavation because of the proximity to structural footings and underground infrastructure critical to operation of the GSE facility.
3.4 TERRESTRIAL ECOLOGICAL EVALUATION
Based on preliminary site scoring using the Simplified Terrestrial Ecological Evaluation – Exposure Analysis Procedure under WAC 173-
FINAL
ERM 10 UAL/0099081/NOVEMBER 2009
340-7492(2)(a)(iii), Table 749-1 in MTCA (Appendix F), no terrestrial ecological evaluation is required.
FINAL
ERM 11 UAL/0099081/NOVEMBER 2009
4.0 CONCLUSIONS AND RECOMMENDATIONS
4.1 CONCLUSIONS
It is ERM’s opinion that site characterization is complete based on MTCA requirements (Chapter 173-340-350 WAC), and no further characterization is required. Approximately 50 cubic yards of soils with mineral oil at concentrations greater than the MTCA Method A cleanup level of 4,000 mg/kg remain at the site. Groundwater quality is not likely affected by this release, nor is it expected in the future if the recommendations in Section 4.2 are implemented. Vapor intrusion is not a concern associated with this release.
4.2 RECOMMENDATIONS
Based on the volume and nature of the released hydraulic oil, as well as the conditions that limit any exposure pathways (e.g., location beneath a concrete slab and no impact to groundwater), ERM recommends that the impacted soils remain in place until structural changes in the building (e.g., remodeling or demolition) allow for the exposure and excavation of the impacted soils for disposal. It is ERM’s opinion that remediation could not be completed under current conditions without significant disruption of critical UAL airport operations. On-site workers should be protected from dermal exposure by requiring appropriate notification of conditions and training for any workers that would complete subsurface work in the release area (e.g., utility line placement).
Based on available data, it is ERM’s opinion that the no further action is warranted for compliance with MTCA until a change in building operations or use status allows for completion of soil removal efforts. If soil removal is completed, soil screening and sampling should be completed in accordance with MTCA requirements and Ecology policy and guidance to confirm removal of soils with hydraulic oil concentrations greater than the MTCA Method A cleanup level.
FINAL 5.0 REFERENCES
Aspect Consulting. 2005. Seattle-Tacoma International Airport Phase 1 Groundwater Study Report. 15 February 2005.
Enviro-Sciences, Inc. 2002. Subsurface Investigation Report, United Airlines Fuel Hydrant System, Seattle-Tacoma International Airport, Seattle, Washington. 14 August 2002.
Environmental Resources Management. 2005. United Airlines Fuel Hydrant System Site Investigation and Regulatory Closure Report, Seattle-Tacoma International Airport, Seattle, Washington. May 2005.
Washington State Department of Ecology. 2003. Model Toxics Control Act Cleanup Regulation, Chapter 173-340 Washington Administrative Code, Amended February 12, 2001. Publication Number 94-06, Revised January 2003.
ERM 12 UAL/0099081/NOVEMBER 2009
Figures
sion.hillebrand
FINAL
sion.hillebrand
FINAL
sion.hillebrand
FINAL
sion.hillebrand
FINAL
sion.hillebrand
FINAL
Tables
FINAL
Table 1Summary of Petroleum Hydrocarbons Detected in Soil
United Airlines Ground Equipment Maintenance FacilitySeattle-Tacoma International Airport
Notes:Concentrations reported in milligrams per kilogram (mg/kg)Shaded cells indicate concentratiosn greater than applicable cleanup standards1Analyzed using Washington State Department of Ecology Method NWTPH-Dx2Sampled soil subsequently removed by excavation of approx. 1/4 cubic yard of petroleum-impacted soil on 30 June 20093MTCA Method A Soil Cleanup Level for Unresticted Land Uses (Chapter 173-340-900 Washington Administrative Code)MTCA = Model Toxics Control Act
MTCA Method A Cleanup Level3 4,000
ERM Page 1 of 1 UAL/0099081 - NOVEMBER 2009
FINAL
Table 2Summary of Extractable Petroleum Hydrocarbons in Soil United Airlines Ground Equipment Maintenance Facility
Seattle-Tacoma International AirportSeattle, Washington
Notes:Concentrations reported in milligrams per kilogram (mg/kg)1Extractable Petroleum Hydrocarbons by Washington State Department of Ecology Method NW-EPH