NAVAL COMPUTER AND TELECOMMUNICATIONS AREA …2.14.5 Location-Specific ARARs/TBC Criteria 38 2.14.6 Action-Specific ARARs/TBC Criteria 39 2.14.7 Cost-Effectiveness of Final Remedy

Record of Decision Old Incinerator Site NAVAL COMPUTER AND TELECOMMUNICATIONS AREA MASTER STATION, PACIFIC, OAHU, HAWAII

September 2009

Department of the Navy Naval Facilities Engineering Command, Hawaii 400 Marshall Road Pearl Harbor, HI 96860-3139

Comprehensive Long-Term Environmental Action Navy Contract Number N62742-03-D-1837, CTO 0008

SDMS DOCID# 1132127

CONTENTS

i

Acronyms and Abbreviations iii

1. Declaration 1

1.1 Site Name and Location 1 1.2 Statement of Basis and Purpose 1 1.3 Assessment of Site 1 1.4 Description of the Selected Remedy 2 1.5 Statutory Determinations 2 1.6 Data Certification Checklist 7 1.7 Signature and Support Agency Acceptance of Final Remedy 9

2. Decision Summary 11

2.1 Site Name, Location, and Description 11 2.2 Site History and Enforcement Activities 11

2.2.1 Site History 11 2.2.2 Enforcement Activities 12

2.3 Community Participation 12 2.4 Scope and Role of Response Action 13 2.5 Site Characteristics 14

2.5.1 Site Description and Location 14 2.5.2 Physical Setting 14 2.5.3 Geology and Hydrogeology 14 2.5.4 Source of Contamination 15 2.5.5 Soil Sampling Strategy and Results 15 2.5.6 Conceptual Site Model 18 2.5.7 Sensitive Populations, Habitats, and Natural Resources 19

2.6 Current and Potential Future Site and Resource Uses 19 2.7 Summary of Site Risks 20

2.7.1 Human Health Screening Risk Assessment 25 2.7.2 Human Health SRA Conclusions 26 2.7.3 Ecological Screening Risk Assessment 26

2.8 Response Action Objectives 27 2.9 Description of Alternatives 28

2.9.1 Description of Alternative Components 28 2.10 Comparative Analysis of Alternatives 29 2.11 Principal Threat Waste 30 2.12 Selected Final Remedy 30

2.12.1 Summary of the Rationale for the Selected Final Remedy 30

2.12.2 Description of the Selected Final Remedy Components 35 2.12.3 Land Use Control Performance Objectives 35 2.12.4 Summary of the Estimated Final Remedy Costs 36 2.12.5 Expected Outcome of the Selected Final Remedy 36 2.12.6 Selected Final Remedy Ongoing Activities 36

2.13 Contribution to Response Performance 37 2.14 Statutory Determination 37

2.14.1 Protection of Human Health and the Environment 37 2.14.2 Compliance with Applicable or Relevant and

Appropriate Requirements 37 2.14.3 Identification of ARARs/TBC Criteria 37 2.14.4 Chemical-Specific ARARs/TBC Criteria 38

September 2009 Record of Decision, Old Incinerator Site Contents

i i

2.14.5 Location-Specific ARARs/TBC Criteria 38 2.14.6 Action-Specific ARARs/TBC Criteria 39 2.14.7 Cost-Effectiveness of Final Remedy 39 2.14.8 Utilization of Permanent Solutions and Alternative

Treatment Technologies 39 2.14.9 Preference for Treatment as a Principal Element 39 2.14.10 Five-Year Review Requirement 40

2.15 Documentation of Significant Changes 40

3. Responsiveness Summary 40

3.1 Stakeholder Issues and Lead Agency Responses 40 3.2 Technical and Legal Issues 40

4. References 41

ATTACHMENTS

A Responsiveness Summary

B Federal Facility Land Use Control ROD Checklist

C Detailed Reference Table

FIGURES

1 Facility Location Map, Old Incinerator Site 3

2 Old Incinerator Site, Building 6 Disposal Area, and Dump Site Near Building 293 5

3 Human Health Conceptual Site Model for the OIS 21

4 Ecological Health Conceptual Site Model for the OIS 23

TABLES

1 Organic Compounds Detected in OIS Soil 15

2 Metals and Cyanide Detected in OIS Soil 16

3 Summary of Human Health Risk Assessment Results for the Old Incinerator Site 25

4 Criteria for Detailed Evaluation of the Response Action Alternatives 29

5 Detailed Analysis of Response Action Alternatives – Old Incinerator Site 31

6 Cost-Effectiveness Summary and Selection of Recommended Alternatives – OIS 36

7 Chemical-Specific Applicable or Relevant and Appropriate Requirements and To Be Considered Guidance 38

8 Location-Specific Applicable or Relevant and Appropriate Requirements and To Be Considered Guidance 38

9 Action-Specific Relevant and Appropriate Requirements (ARARs) and To Be Considered Guidance 39

ACRONYMS AND ABBREVIATIONS

i i i

§ Section ARAR applicable or relevant and appropriate requirements bgs below ground surface Bldg. building CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CERCLIS Comprehensive Environmental Response, Compensation, and Liability

Information System CFR Code of Federal Regulations CLEAN Comprehensive Long-Term Environmental Action Navy COPC chemical of potential concern CSM conceptual site model DoD Department of Defense DOH State of Hawaii Department of Health DON Department of the Navy EPA Environmental Protection Agency, United States EPC exposure point concentration ERA ecological risk assessment FS feasibility study gpd gallons per day HI hazard index HQ hazard quotient IAS initial assessment study LUC land use control mg/kg milligram per kilogram mg/L milligram per liter NAVFAC Hawaii Naval Facilities Engineering Command, Hawaii NCP National Oil and Hazardous Substances Pollution Contingency Plan NCTAMS PAC Naval Computer and Telecommunications Area Master Station, Pacific NOAEL no-observed-adverse-effect-level No. number NPL National Priority List NRTF Naval Radio Transmitting Facility OIS Old Incinerator Site ORNL Oak Ridge National Laboratory OU operable unit PAH polynuclear aromatic hydrocarbon pg/p parts per trillion PP proposed plan PRG preliminary remediation goal RAB restoration advisory board RACR Remedial Action Completion Report RI remedial investigation RME reasonable maximum exposure ROD record of decision SARA Superfund Amendments and Reauthorization Act SRA screening risk assessment TBC to be considered TRV toxicity reference value U.S. United States U.S.C. United States Code WP work plan

September 2009 Record of Decision, Old Incinerator Site Page 1 of 42

1. Declaration 1.1 SITE NAME AND LOCATION This Record of Decision (ROD) has been prepared by the United States (U.S.) Navy (Navy) for the Old Incinerator Site (OIS) located within the Naval Computer and Telecommunications Area Master Station, Pacific (NCTAMS PAC), Wahiawa, Oahu, Hawaii (Figure 1). The former incinerator was located on the western edge of the gulch behind Building (Bldg.) 336, NCTAMS PAC Wahiawa. NCTAMS PAC Wahiawa is one of two operable units (OUs) located within the NCTAMS PAC National Priority List (NPL) site. The Naval Radio Transmitting Facility (NRTF) is the second OU within the within the NCTAMS PAC facility. NCTAMS PAC Wahiawa is identified on the NPL as U.S. Environmental Protection Agency (EPA) Comprehensive Environmental Response, Compensation, and Liability Information System (CERCLIS) Number (No.) HI0170090054.

This ROD has been prepared for the Naval Facilities Engineering Command, Hawaii (NAVFAC Hawaii) under the Comprehensive Long-Term Environmental Action Navy (CLEAN) III program, Contract No. N62742-03-D-1837, Contract Task Order No. 0008. This ROD incorporates elements of a streamlined Remedial Action Completion Report (RACR), as described in the Department of Defense (DoD)/EPA Joint Guidance on Streamlined Site Closeout and NPL Deletion Process for DoD Facilities (DoD 2006) and U.S. Department of the Navy (DON) Guidance to Documenting Milestones Throughout the Site Closeout Process (DON 2006b).

1.2 STATEMENT OF BASIS AND PURPOSE This ROD documents, for the Administrative Record, the decision by DON, the State of Hawaii Department of Health (DOH) and EPA to undertake a response action at the OIS. The ROD substantiates the need for the response action, evaluates response action alternatives, identifies the selected response action alternative, and presents the rationale for the recommended response action approach. The proposed response action is required to mitigate potential risks to site users from exposure to contaminated surface soil.

This ROD presents the selected final remedy for the OIS. The final decision was chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), as amended by the Superfund Amendments and Reauthorization Act (SARA), 42 United States Code (U.S.C.) Section 9601, et seq., the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40 CFR Part 300, and the Office of the President U.S. Executive Order 12580. Information supporting the decisions leading to the selected remedy is contained in the Administrative Record file for the site. DOH concurs with this decision as indicated by signature in Section 1.7.

1.3 ASSESSMENT OF SITE The OIS, which is unused and vacant, occupies about 0.14 acres of land within the same gulch as another disposal site, the Bldg. 6 Disposal Area (Figure 2). The response action selected in this ROD is necessary to protect the public health or welfare or the environment from actual or potential releases of hazardous substances into the environment from the OIS.


1.4 DESCRIPTION OF THE SELECTED REMEDY The Navy and EPA Region 9, in coordination with EPA Headquarters and with the concurrence of the DOH, have selected land use controls (LUCs)1

This remedy will ensure that the contaminated soils are not disturbed and that potential routes for exposure are not created due to future land uses or land use changes.

as the remedy for the OIS. LUCs, which include the implementation and maintenance of institutional controls, are designed to (1) restrict land use to activities, and (2) ensure long-term viability of the final remedy.

The LUC elements of the selected final remedy include the following:

Site access control

Land use restrictions

Recording the land use restrictions in the facility planning records/land use database

Five-year reviews

Access restriction will consist of warning signage to prohibit unauthorized access to the OIS. Land use restrictions will be implemented by the Navy to prohibit any land modifications (e.g., vegetation clearing, regrading, excavation, landscaping, and construction of structures) that could potentially expose contaminated soil at the site. Records of the land use restrictions will be maintained in the facility planning documents/land use database.

The implementation and maintenance of, and compliance with, LUCs will be confirmed by annual inspections to be performed by the Navy. A LUC Work Plan (WP) has been prepared and submitted by the Navy (Earth Tech 2008). The LUC WP will be finalized to detail how the specific LUCs will be implemented and maintained, and specifies the requirements for annual inspections and five-year reviews (Earth Tech 2008).

The response action objective of protecting human health and the environment is achieved through implementation of the selected remedy: LUCs. Therefore, the OIS will be in a protective state for human health and the environment. This decision is supported by documents in the information repository for NCTAMS PAC Wahiawa. The Restoration Advisory Board (RAB) composed of representatives of the DOH, EPA, Navy, and the community provided review and comment leading to selection of this decision.

1.5 STATUTORY DETERMINATIONS The Navy is the lead agency for environmental cleanup at Navy sites, such as the implementation of LUCs at the OIS. The EPA and DOH have provided oversight during environmental investigations and cleanup activities on Navy properties. The selected remedy described in Section 1.4 is protective of human health and the environment, complies with federal and state applicable or relevant and appropriate requirements (ARARs), is cost-effective, and uses, to the maximum extent practicable, permanent solutions and alternative treatment technologies.

1 Text in blue font identifies where detailed cross-reference site information is available (Attachment C). In the event of any inconsistency between the text in this ROD and the text in any of the cross-reference documents, the text in this ROD will take precedence.


The NCP, 40 CFR Section 300.430(a)(1)(iii)(A), establishes the expectation that treatment will be used to address the principal threats at a site where practicable. The selected remedy for the OIS does not satisfy the statutory preference for treatment as a principal element of the final remedy, because there are no source materials constituting principal threats, the remote nature of the site, and the limited risk reduction that would be attained through the use of treatment as a remedy component.

Because this final remedy results in hazardous substances, pollutants, or contaminants remaining on site above levels that allow for unlimited use and unrestricted exposure, the five-year review requirement under CERCLA Section 121(c), 42 U.S.C. Section 9601(c) and the NCP, 40 CFR Section 300.430(f)(4)(ii) is applicable to ensure that the selected final remedy remains protective of human health and the environment. The five-year reviews will be conducted by the Navy.

1.6 DATA CERTIFICATION CHECKLIST The following information is included in the Decision Summary section of this ROD (Section 2). Additional information can be found in the Administrative Record file for the OIS.

Chemicals of potential concern (COPCs) (Section 2.5.5) Current and reasonably anticipated future land use assumptions used in the risk assessments

and Decision Document (Section 2.6) Summary of pre-removal action human health risks (Section 2.7) How source materials constituting principal threat are addressed (Section 2.11) Potential land and groundwater use that will be available at the site as a result of the selected

final remedy (Sections 2.6 and 2.12.5) Key factors that led to selecting the final remedy (Section 2.12.1)

Estimated capital, annual monitoring and maintenance, and total present worth cost, discount rate, and the number of years over which the remedy cost estimates are projected (Section 2.14.7)


2. Decision Summary 2.1 SITE NAME, LOCATION, AND DESCRIPTION The OIS is situated on the southern flank of the Bldg. 6 gulch behind Bldg. 336 at NCTAMS PAC Wahiawa (Figure 2). The gulch is approximately 60 feet deep and densely vegetated. An unnamed intermittent stream flows through the gulch and past the OIS. The OIS is presently unused, vacant, and comprises steps, a landing, and the foundation of a former incinerator in which controlled documents were burned. The surrounding area is a secure military facility used for industrial/commercial activities. Executive Order 12580 authorizes DON to act as the lead agency for environmental response actions at Navy sites, such as the OIS. EPA and DOH have provided oversight during the environmental investigation activities at the OIS. Funding for the site work at OIS is provided by the Navy Environmental Restoration Program.

2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES 2.2.1 Site History

The NCTAMS PAC Wahiawa operates and maintains communications facilities for the Navy in the eastern Pacific. It is part of the Defense Communications System and of the military satellite communications system.

Discarded controlled documents and other miscellaneous wastes were burned in an incinerator on the western edge of the gulch behind Bldg. 336. Ash from the incinerator was disposed of at the OIS, which occupies about 0.14 acres of land within the same gulch as the Bldg. 6 Disposal Area, and was formerly included in the Bldg. 6 Disposal Area as the “Burn Area.” The incinerator was removed in 1975. Remnants of the incinerator include a concrete foundation, steps, and a single wall near the top of the gulch slope. Immediately downslope of the concrete foundation, the ground is covered with ash, small amounts of slag (i.e., melted metal), and other miscellaneous wastes. Ash has been reported to depths up to 11 feet below ground surface (bgs). The presence of ash at depth indicates that the ash was occasionally covered with soil. The presence of slag materials indicates materials other than paper may also have been burned during document destruction.

NCTAMS PAC Wahiawa has been the subject of four previous environmental investigations:

An initial site assessment (NEESA 1986)

A site inspection (HLA 1989)

An expanded site inspection (ANL 1992)

A remedial investigation (RI) (Earth Tech 2006)

The OIS was considered within the Bldg. 6 Disposal Area during the first three of these investigations, and was investigated as a separate site during the RI.

Initial Assessment Study. An initial assessment study (IAS) was conducted by the Naval Energy and Environmental Support Activity. The purpose of the study was to identify areas that may require further investigation or cleanup. The IAS report (NEESA 1986) recommended that a site inspection be conducted to determine whether contamination existed at the Bldg. 6 Disposal Area and to develop recommendations for further action.

Site Inspection. A site inspection was conducted by the Navy to characterize the Bldg. 6 Disposal Area by determining the presence or absence of contamination in the surface and subsurface soil. The Bldg. 6 Disposal Area encompasses the former location of the incinerator and the adjacent area


of ash identified during the site inspection as the “Burn Area.” The site inspection report (HLA 1989) concluded that arsenic, lead, mercury, and xylene in soil may be the result of historical waste management practices.

Expanded Site Inspection. A supplemental or expanded site inspection was conducted by the Navy to further investigate the Bldg. 6 Disposal Area (ANL 1992). Investigators concluded that elevated concentrations of lead are common in surface soil and sediment samples, although only one detection exceeded the Corrective Action Level used for comparison. Results for subsurface samples correlated with surface and sediment samples and defined some contaminant sources, including the OIS. The great depth to the groundwater and the presence of intervening clay layers greatly reduce the risk of groundwater contamination. While the surrounding civilian population was concluded to probably not be at immediate risk (they are unlikely to come into direct contact with the soil), the offsite civilian population was considered potentially at risk because of possible transport of contaminants via surface drainage. Naval personnel were concluded to be the most at risk via direct contact with contaminated soil.

Remedial Investigation. The Navy completed a RI (Earth Tech 2006) based on the findings and recommendations of the two site inspections. The initial scope of the RI was to collect and evaluate the data needed to quantify risk associated with the Bldg. 6 Disposal Area and, if necessary, to identify appropriate remedial actions. The OIS was not included in the original scope of the RI. However, observations made during the initial RI field reconnaissance in 1996 revealed concerns about the site, and it was added to the RI scope. The RI Report (Earth Tech 2006) identified two organic chemicals; (benzo(a)pyrene and benzo(b)fluoranthene), and four metals; antimony, arsenic, copper, and lead, as COPCs in soil. Human health and ecological risks were below target points of departure for surface soil. Human health and ecological risk estimates for subsurface soil indicated that mitigation through LUCs or a removal action may be required for the OIS to protect human health and the environment.

During the RI, no dioxins were detected; however, the reporting limits for dioxin exceeded the then current residential preliminary remediation goal (PRG). During additional sampling performed in 2006, eight surface soil samples and seven subsurface soil samples were collected and analyzed for antimony, arsenic, copper, lead, and dioxins. The subsurface soil samples had exceedances of the EPA Region 9 industrial PRGs for arsenic (six of seven samples), dioxin (four of seven samples), and lead (one of seven samples). These additional sample analytical results supported the RI conclusion for the need for a response action to mitigate site risks.

2.2.2 Enforcement Activities

There have been no enforcement activities at OIS at NCTAMS PAC Wahiawa, Oahu, Hawaii.

2.3 COMMUNITY PARTICIPATION Public participation in the decision process for environmental activities at NCTAMS PAC Wahiawa has continually been encouraged throughout the environmental restoration and site closure processes. In an effort to involve the public in the decision-making process, a RAB was established. The RAB is composed of the DOH, EPA, Navy, and community representatives. The Navy has held RAB meetings (typically on a semi-annual basis) and other public meetings, as well as issued fact sheets that summarize the site investigation and cleanup activities. The RAB has provided review and comment to the site information and risk management decisions leading to the selection of LUCs as the final remedy at OIS. Additionally, the Navy also established a point-of-contact for the public in the NAVFAC Hawaii.


A Proposed Plan (PP) (DON 2007) was prepared to formally present the proposed remedy to the public and to solicit public comment. A public meeting for the PP was held on 7 June 2007 at the Wahiawa District Park. The public comment period for the PP was held between 8 June 2007 and 7 July 2007. Responses to the written and verbal comments received during the comment period and public meeting are presented as a Responsiveness Summary in Attachment A within this ROD. The complete transcript of the public meeting is available in the Administrative Record file.

Throughout the investigation process, the Navy has prepared various fact sheets to inform and update the community on the progress of NCTAMS PAC Wahiawa environmental investigation and cleanup activities. These fact sheets and other project documents, including work plans, technical reports, and other materials relating to the NCTAMS PAC Wahiawa investigation activities, can be found in the information repository at the following addresses:

Wahiawa Public Library 820 California Avenue Wahiawa, Hawaii 96786 (808) 622-6345

Hamilton Library at the University of Hawaii at Manoa Hawaiian and Pacific Collection 2550 McCarthy Mall Honolulu, Hawaii 96822 (808) 956-8264

Additional project information is located in the Administrative Record file located at NAVFAC Pacific in Pearl Harbor. The address for the Administrative Record file is provided below:

Naval Facilities Engineering Command, Pacific 258 Makalapa Drive, Suite 100 Attn: NAVFACPAC EV4 Pearl Harbor, Hawaii 96860 (808) 472-1428

2.4 SCOPE AND ROLE OF RESPONSE ACTION The OIS is located at NCTAMS PAC Wahiawa, which in turn is an OU within the NCTAMS PAC. NCTAMS PAC was listed on the NPL on 31 May 1994. The NPL identifies priorities among known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the U.S. and its territories. The Navy, EPA, and DOH signed a Federal Facilities Agreement (EPA Region 9, State of Hawaii, and DON 2009), effective July 2009, in which they agreed to:

Ensure that environmental impacts associated with past activities conducted are thoroughly investigated and that appropriate remedial actions are taken, as necessary, to protect public health, welfare, and the environment;

Establish a procedural framework and schedule for developing, implementing, and monitoring appropriate remedial actions in accordance with CERCLA, SARA, NCP, Superfund guidance and policy, Resource Conservation and Recovery Act guidance and policy, and applicable State of Hawaii law;

Facilitate cooperation, exchange of information, and participation of the Navy, EPA, and State of Hawaii; and


Ensure adequate assessment of potential injury to natural resources necessary to ensure the

A response action is necessary to protect human health and the environment from polynuclear aromatic hydrocarbons (PAHs), metals, and dioxins present in surface and shallow subsurface soil. LUCs are appropriate for sites where limited risk to human health or the environment exists and the risk can be effectively managed through controlling access to and future uses of the site. Based on soil sample analytical results presented in the RI Report (Earth Tech 2006), the DOH, EPA, and Navy concluded that the limited risks to human health and the environment are manageable with LUCs at this site.

implementation of response actions appropriate for achieving clean-up levels.

2.5 SITE CHARACTERISTICS 2.5.1 Site Description and Location

The OIS covers approximately 0.14 acres and is located in the south-central portion of NCTAMS PAC Wahiawa near two other Installation Restoration sites: Bldg. 6 Disposal Area and Dump Site Near Bldg. 293. A fourth Installation Restoration site, the Old Wahiawa Landfill,

2.5.2 Physical Setting

occupies the head of the gulch and is located approximately 3,200 feet from the other three sites. The OIS lies within a steep wooded gulches atop weathered basaltic flows.

NCTAMS PAC Wahiawa is located on the Schofield Plateau at an elevation of approximately 1,300 feet above mean sea level. The plateau, which forms central Oahu between the Koolau and Waianae Ranges, was created when Koolau lava flows overlapped the flanks of the older Waianae Range. Near the facility, the plateau slopes gently westward, corresponding to the dip of the underlying lava beds. A thick layer of surface soil covering most of the facility is dissected by a system of narrow, steep-sided gullies formed by erosion. Land bordering the facility is largely agricultural and devoted to pineapple cultivation. The nearest urban area is the town of Wahiawa, located about 1 mile south of the facility.

2.5.3 Geology and Hydrogeology

Three stratigraphic units overlie the deep Waianae Volcanics beneath NCTAMS PAC Wahiawa (Earth Tech 2006):

The upper unit is silty clay or clayey silt laterite (ranging from 8 to 13 feet thick), a reddish soil formed by weathering of the Koolau Volcanics. In the gullies, the surface soil is silty clay or clayey silt alluvium deposited in the beds of intermittent streams.

Below the upper unit is saprolite, ranging from 10 to 100 feet thick, formed by weathering of the Koolau Volcanics. Saprolite is distinguished from the overlying soil by its residual basaltic structure and texture, including fractures and vesicles.

Unweathered to moderately weathered Koolau Volcanics deposited as lava and tuff flows underlie the saprolite. The lava and tuff flows crop out near the crest of the Koolau Range. Unweathered Koolau volcanic rocks are highly permeable, jointed, dense to very dense vesicular basalt.

The RI indicated that the OIS is underlain by ash, silty clay fill with ash, and saprolite. Approximately 6 inches of surface soil overlay the ash layer which ranges from 3 feet to 11 feet in thickness (Earth Tech 2006).


Groundwater of the Schofield High-Level Aquifer lies within the fractured basalt of the Koolau Volcanic Series and, possibly, at greater depths within the Waianae Volcanics. Basalt dikes form relatively impermeable barriers in the permeable volcanic rock. The dikes divert groundwater to successively lower compartments, creating step-like breaks in the water table. Groundwater flows westward. The potentiometric surface of the aquifer at NCTAMS PAC Wahiawa is 800 to 900 feet bgs, based on initial water level measurements in Well No. 3-3100-02, which taps the Schofield Aquifer beneath NCTAMS PAC Wahiawa. The well is located approximately 3,000 feet westward and downgradient of OIS. According to the well log, it is 960 feet deep, and there is a low permeability layer of clay located between 125 and 129 feet bgs. This well has supplied municipal water to NCTAMS PAC Wahiawa since April 1997, and is sampled quarterly by the DOH.

Perched water occurs locally where less permeable strata impede the downward flow of surface water. The perched water is not used for drinking water and is distinct from the regional water supply, the Schofield Aquifer (Earth Tech 2006). At the nearby Bldg. 6 Disposal Area, limited, perched water was encountered at depths of 8 to 10 feet bgs in two borings into the gulch floor alluvium; however, neither surface water nor groundwater were encountered at the OIS during the RI (Earth Tech 2006).

2.5.4 Source of Contamination

The main source of contamination is the residual ash from past incinerator operations, which burned controlled documents destined for disposal and other miscellaneous wastes.

2.5.5 Soil Sampling Strategy and Results

During the RI, surface and subsurface soil samples were collected and analyzed for organic compounds and metals. Surface water and groundwater were not encountered at the site and therefore were not sampled. Table 1 and Table 2 present the analytical results for organic contaminants and metals in OIS soil based on 6 surface and 14 subsurface soil samples collected during the RI. Based on the RI data, the following chemicals were identified as COPCs for soil: two PAHs (benzo[a]pyrene and benzo[b]fluoranthene); and four metals (antimony, arsenic, copper, and lead). The PAH exceedances occurred in a single subsurface soil sample, indicating that the extent of PAH contaminations at the OIS is likely limited. With the exception of one lead exceedance, all metals exceedances above estimated background concentrations occurred in subsurface soil. Metals at the OIS appeared to be predominately associated with ash layers in the subsurface.

Table 1: Organic Compounds Detected in OIS Soil

Compound No. of Detects Concentration

Range (mg/kg) Residential PRG

(mg/kg) a Industrial PRG

(mg/kg) a PRG Qualifier F B VOCs Acetone — 5 0.007 J–47 J 14,000 54,000 nc Xylene (total) — 1 0.005 J 270 420 nc (sat) SVOC Benzo(a)anthracene 0 1 0.420 J 0.62 2.1 ca Benzo(a)pyrene 0 1 0.340 J 0.062 0.21 ca Benzo(b)fluoranthene 0 2 0.450–0.720 0.62 2.1 ca Benzo(k)fluoranthene 0 1 0.250 J 6.2 21 ca Bis(2-ethylhexyl)phthalate

0 2 0.310 J –0.570 35 120 cab (ca)

Chrysene 0 2 0.240 J –0.580 62 210 ca Fluoranthene 1 1 0.150 J –0.750 2,300 22,000 nc Phenanthrene 1 0 0.100 J NS NS N/A Pyrene 1 1 0.087 J –0.880 2,300 29,000 nc


Compound No. of Detects Concentration

Range (mg/kg) Residential PRG

(mg/kg) a Industrial PRG

(mg/kg) a PRG Qualifier F B TPHs TPH-DRO 4 6 9.60 J –49.0 J 500 c N/A N/A Pesticide/PCB 4,4'-DDD 2 0 0.0093 NJ–0.014 J 2.4 10 ca 4,4'-DDE 2 5 0.0071–0.240 J 1.7 7.0 ca 4,4'-DDT 3 5 0.0032 J –0.230 J 1.7 7.0 cab

Chlordane (α and γ) d 2 1 0.0013 NJ–0.024 NJ 1.6 6.5 cab

Heptachlor epoxide 1 0 0.002 NJ 0.053 0.19 cab

PCBs (total) e 0 1 0.025 J 0.22 0.74 caf (cab) Aroclor 1260 e 0 1 0.025 J 0.22 0.74 caf (cab) Chlorinated Herbicides 2,4,5-T 0 1 0.0044 NJ 610 6,200 nc 2,4-DB 2 1 0.059 J –0.120 J 490 4,900 nc Organophosphorus Pesticides and Carbamate/Urea Pesticides Monocrotophos 0 1 0.066 J NS NS N/A Text in bold italics identify concentrations that exceeding EPA Region 9 (2004) residential PRG. Text in bold identify concentrations that exceed EPA Region 9 (2004) industrial soil PRGs. PRG Qualifier: ( ) indicates qualifier for Industrial PRG, if different from Residential PRG qualifier. — No sample taken B subsurface ca cancer PRG DRO diesel range organic F surface J Positively identified – estimated concentration mg/kg milligram per kilogram N/A not applicable nc noncancer PRG NJ Tentatively identified – estimated concentration NS no standard PCB polychlorinated biphenyl sat soil saturation SVOC semivolatile organic compound TPH total petroleum hydrocarbon VOC volatile organic compound a Residential and industrial PRGs are from EPA Region 9 (2004). b The noncancer PRG would be exceeded if the cancer value listed is multiplied by 100. c The standard of comparison for TPH is the DOH Tier 1 Action Level, rather than a PRG. Values are listed for soil levels with

SW >150m and with GW not a potential drinking source. d PRGs are listed for technical chlordane. e PRG values for Aroclor 1254 are listed for total PCBs and for Aroclor 1260. f The noncancer PRG would be exceeded if the listed cancer value is multiplied by 10.

Table 2: Metals and Cyanide Detected in OIS Soil

Metal

No. of Detects

Concentration Range (mg/kg)

Residential PRG

(mg/kg) a

Industrial PRG

(mg/kg) a PRG

Qualifier

Estimated Background

Upper Bound (mg/kg)b F B

Aluminum 6 11 18,500 J –66,800 J 76,000 100,000 nc (max) 156,000 Antimony 4 10 3.1 J –67 31 J 410 nc 7 Arsenic 4 9 0.62 J –42.3 0.390 J 1.6 cac (ca) 22 Barium 6 11 16–1,550 5,400 J 67,000 nc 293 Beryllium 3 2 0.24 J –0.62 J 150 1,900 nc (cad) 5.7 Cadmium 1 5 0.32 J –10.9 37 J 450 nc 2 Calcium 6 11 233–87,200 NS NS N/A 360,000 Chromium 6 11 20.2 J –434 210 450 ca 599 Cobalt 6 11 5.6 J –27.9 900 1,900 cad (cac) 157


Metal

No. of Detects

Concentration Range (mg/kg)

Residential PRG

(mg/kg) a

Industrial PRG

(mg/kg) a PRG

Qualifier

Estimated Background

Upper Bound (mg/kg)b F B

Copper 6 11 48.9– 3,100 4,600 41,000 nc 235 Cyanide 1 3 0.24–1 11 35 nc NS Iron 6 11 15,600 J –127,000 23,000 100,000 nc (max) 219,000 Lead 6 11 4.5–6,910 400 J 800 nc 117 Magnesium 6 11 251–5,030 NS NS N/A NS Manganese 6 11 167 J –1,100 1,800 19,000 nc 7,040 Mercury 6 10 0.13– 23 1.1 310 nc 1 Nickel 6 11 12.1– 1,600 1,080 20,000 nc 579 Potassium 6 11 103–5,630 NS NS N/A NS Selenium 5 3 1.3 J –7.1 J 390 5,100 nc 11 Silver 4 8 0.18 J – 390 214 5,100 nc 3.1 Sodium 2 4 87.2–7,050 NS NS N/A NS Thalliume 1 1 3.2 J –3.9 J 5.2 67 nc 4.8 Vanadium 6 11 16.1 J –316 J 78 1,000 nc 560 Zinc 6 11 40.2 J – 23,000 9,780 100,000 nc (max) 214 Text in bold italics identifies concentrations that exceed EPA Region 9 (2004) residential PRGs. Text in bold identifies concentrations that exceed EPA Region 9 (2004) industrial soil PRGs. Text that is underlinedB subsurface

identifies concentrations that exceed the background value (if a background range is quantified).

ca cancer PRG F surface J Estimated concentration max PRG concentration exceeds the ceiling limit concentration of 100,000,000 µg/kg. mg/kg milligram per kilogram N/A not applicable nc noncancer PRG NS no standard PRG preliminary remediation goal a Residential and industrial PRGs are from EPA Region 9 (2004). b Estimated upper bound of background range, as discussed in Appendix C of the RI report (Earth Tech 2006). c The noncancer PRG would be exceeded if the cancer value listed is multiplied by 100. e Thallium residential PRG derived from thallic oxide. d The noncancer PRG would be exceeded if the listed cancer value is multiplied by 10.

Additional soil sampling performed in November 2006 at the OIS for further evaluation of dioxins and metals in soil was conducted using multi-increment sampling techniques. In addition, seven locations had discrete subsurface soil samples collected. All of the additional soil samples were analyzed for the four metals identified in the RI as COPCs (antimony, arsenic, copper, lead), and for dioxins. The surface soil data provided an average concentration of the analytes within each of eight decision units. Based on regulator comments, the eight original decision units were combined into four decision units that were closer to the size of a standard residential lot, or approximately 5,000 square feet. The results were averaged within each combined unit to reflect the average exposure concentration of the analytes within a residential lot. None of the decision units were found to have surface soil exceedances of the prevailing industrial PRGs for the COPCs.

The analytical results for the seven subsurface samples indicated exceedances of the then current residential PRGs for arsenic, lead, and dioxin. Four of the seven subsurface soil samples also exceeded the then current industrial PRGs for lead and dioxin. Dioxin values ranged from 0.169 parts per trillion (pg/g) to 68.4 pg/g, which exceeded the prevailing industrial PRG (EPA 2004), but was well within the Office of Solid Waste and Emergency Response recommended industrial PRG cleanup level of 5,000 to 20,000 pg/g (EPA 1998). The EPA has generally selected a cleanup level for dioxin within this range for commercial/industrial soils at Superfund and Resource Conservation and Recovery Act cleanup sites where dioxin is a principal contaminant of concern at the facility.


The levels that EPA has selected at these sites are based on estimated risks within the CERCLA target range of 10–4 to 10–6 and are protective of human health and the environment.

Although no groundwater sampling was conducted during the OIS RI, the probability that contaminant release and transport to groundwater (the Schofield Aquifer) was concluded to be low because of the following:

The depth to the principal aquifer is deep, approximately 900 feet bgs.

The low to moderate permeability of the intervening soil and rock limit the capacity for contaminant infiltration and migration. The Schofield Plateau was formed by ponding of lava and tuff flows from the Koolau range on the eroded slope of the Waianae Range (Stearns 1985). Recharge is by infiltration of rainwater from the Koolau Range, and by rainwater and stream flow infiltration on the Schofield Plateau (Earth Tech 2006). Basalt dikes form relatively impermeable barriers in the permeable volcanic rock, diverting groundwater to successively lower compartments, and creating step-like breaks in the water table (Earth Tech 2006).

Contaminant adsorption to the stratigraphic units as detailed in Section 2.5.3 and summarized below is expected to attenuate COPCs in the subsurface:

– The upper unit is silty clay or clayey silt laterite, with silty clay or clayey silt alluvium deposited in the beds of intermittent streams.

– Saprolite ranging from 10 to 100 feet thick underlies the silty clay and laterite soils. The clay component of the saprolite would be expected to retard the movement of organic contaminants in the subsurface.

– Unweathered to moderately weathered Koolau Volcanics deposited as lava and tuff flows underlie the saprolite. Unweathered Koolau volcanic rocks are highly permeable, jointed, dense to very dense vesicular basalt.

The nature and extent of detected COPCs (Organics and Metals).

– Low water solubility and strong sorption to soil particles is expected to limit transport of benzo(a)pyrene and benzo(b)fluoranthene in the unsaturated zone.

– The metals detected (antimony, arsenic, copper, and lead) are components of rock and adsorb readily to minerals surfaces. Therefore, transport of these metals to groundwater is expected to be minimal.

Lithologic logs generated during the installation of the downgradient production well revealed a lower permeability clay layer between 125 and 129 feet bgs that would be expected to retard the vertical migration of any COPCs.

2.5.6 Conceptual Site Model

The conceptual site model (CSM) is used to guide the evaluation of potential exposures so that relevant pathways, exposure routes, and ultimately risk can be evaluated in the screening risk assessment (SRA). The primary purpose of the CSM is to structure the SRA in order to determine whether exposure pathways are incomplete (requiring no further evaluation) or potentially complete. Only potentially complete exposure pathways are evaluated quantitatively in the risk assessment, which is consistent with EPA guidance (EPA 1989). A potentially complete exposure pathway must include all of the following elements before a quantitative assessment is performed:


Sources and type of chemicals present

Affected media

Chemical release and transport mechanisms (e.g., spillage and advection, vaporization)

Known and potential routes of exposure (e.g., ingestion, dermal contact, inhalation)

Known or potential human and environmental receptors (e.g., residents, workers, wildlife)

The absence of any one of these elements results in an incomplete exposure pathway. Thus, for an incomplete pathway with no potential human or ecological exposure, the potential for adverse health effects would be deemed negligible and would not warrant further evaluation.

The CSM developed for the OIS describes the contaminant sources, contaminant migration mechanisms, and receptor exposure pathways potentially present at the site. It is a dynamic model developed from previous investigations for the RI human health and ecological risk assessments (Earth Tech 2006). The CSMs for the OIS are summarized in Figure 3 for human health and Figure 4 for ecological health. Potential human receptors for the OIS include both child and adult trespassers, and offsite nearby residents under the current land use setting, and commercial/industrial workers and both child and adult residents under the future land use setting. The most important potential routes of exposure are direct contact with, and incidental ingestion of contaminated soil and surface water.

2.5.7 Sensitive Populations, Habitats, and Natural Resources

The gulch is subject to water flow during periods of heavy rain. Storm water runoff follows the topography into the Poamoho Stream and its wetlands. Although no federal- or state-listed endangered species are reported within the boundaries of NCTAMS PAC Wahiawa facility, two bird species, the pueo (Asio flammeus sandwichensis) and the Pacific golden plover (Pluvialis fulva) require attention at this location. The state-listed endangered pueo, or Hawaiian short-eared owl, is an endemic subspecies nesting upon the ground and feeding upon small animals. This diurnal raptor may dwell near the facility in open grasslands. The Pacific golden plover is a migratory omnivore protected by the Federal Migratory Bird Treaty Act (1918, with amendments) that may winter in mowed areas of the facility. Habitat within or downstream of the OIS may therefore support one or both of these species.

2.6 CURRENT AND POTENTIAL FUTURE SITE AND RESOURCE USES Current Site Use. The NCTAMS PAC Wahiawa operates and maintains communications facilities for the Navy in the eastern Pacific, which is considered an industrial/commercial use. It is part of the Defense Communications System and of the military satellite communications system. The OIS lies within a steep wooded gulch atop weathered basaltic flows. The OIS is currently unused, and no activities currently occur within the gulch. The site boundaries are shown in Figure 2.

Future Site Use. NCTAMS PAC Wahiawa will be maintained by the Navy for use as a communications facility, which is considered an industrial/commercial use; however, the potential for unrestricted use was also considered. There is no current plan for development of the steep gulch walls, and no land use changes are anticipated in the foreseeable future.

Groundwater Classification and Use. The State of Hawaii does not currently have an EPA-approved comprehensive state groundwater protection plan in place; therefore, federal and other state guidance was considered to determine the status of groundwater at the OIS, as well as site-specific factors. The groundwater in the deep Wahiawa System aquifer at the OIS site was classified in accordance with the Classification of Shallow Caprock Groundwater at Navy Oahu


Facilities, Oahu, Hawaii (Earth Tech 2007a). This classification was developed through a partnership with EPA Region 9 and the DOH to develop and agree upon a framework for groundwater classification at Navy facilities in Hawaii. This framework allows site-specific factors to be considered to determine whether groundwater meets the criteria for beneficial use as a public or private drinking water source in the future as defined in the EPA Groundwater Protection Strategy (EPA 1988).

According to the Guidelines for Ground-Water Classification Under the EPA Ground-Water Protection Strategy (EPA 1988), groundwater is classified as Class I, II, or III, as follows:

Class I groundwater is highly vulnerable to contamination and is an irreplaceable source of drinking water for a substantial population, or is ecologically vital.

Class II groundwater is a current or potential source of drinking water.

Class III groundwater is not a potential source of drinking water and is of limited beneficial use.

The deep Wahiawa System aquifer meets the criteria for Class I groundwater. Under the federal guidelines, a potential source of drinking water (Class I or II) is defined as a groundwater source “capable of yielding a quantity of drinking water to a well or spring sufficient for the needs of an average family.” This yield is established at 150 gallons per day (gpd) or 0.104 gallon per minute sustainable throughout the year. Groundwater is considered suitable for drinking purposes if it has a “total dissolved solids concentration of less than 10,000 milligram per liter (mg/L), which can be used without treatment, or that can be treated using methods reasonably employed in a public water system” (EPA 1988).

2.7 SUMMARY OF SITE RISKS The human health and ecological SRAs are summarized below and are presented in their entirety as Appendix C of the RI Report (Earth Tech 2006).

Current Use

Woodland Trespasser (Adult/Child)

Offsite Resident

Commercial Workers

Residents or Industrial Onsite

Workers (Adult/Child)

Surface Direct Direct Potentially Insignificant Potentially PotentiallySoil Contact Contact Complete Complete Complete

Incidental Potentially Insignificant Potentially PotentiallyIngestion Complete Complete Complete

Insignificant Insignificant Insignificant PotentiallyComplete

Inhalation ofVOCs Insignificant Insignificant Insignificant

PotentiallyComplete

Dermal Potentially Potentially Potentially PotentiallyAdsorption Complete Complete Complete Complete

Incidental Potentially Potentially Potentially PotentiallyIngestion Complete Complete Complete Complete

Bio- Incomplete Incomplete Incomplete IncompleteAccumulation/Consumptionof Fish andVegetables

Subsurface Direct Dermal Incomplete Incomplete IncompleteSoil Contact Adsorption

Incidental Incomplete Incomplete IncompleteIngestion

Dermal Incomplete Incomplete Incomplete IncompleteAdsorption

Incidental Incomplete Incomplete Incomplete IncompleteIngestion

Inhalation Incomplete Incomplete Incomplete Incompleteof VOCs

Drinking Incomplete Incomplete Incomplete IncompleteWater

AirTransport

Because woodland trespassers and commercial workers are unlikely to engage in activities that would expose subsurface soil, the subsurface soil is considered incomplete for woodland trespassers and commercial workers. Direct contact with, and incidental ingestion of, subsurface soil is potentially complete for future onsite workers, future residents engaged in landscaping or construction activities.

No permanent surface water exists at the OIS, NCTAMS PAC Wahiawa. However, following rainfall, there is a potential for water to accumulate in holes and ditches. Dermal adsorption and incidental ingestion of surface water run-off is potentially complete for all current and future receptors assuming there is surficial contamination.

Exposure Route

Air transport of nonvolatile chemicals of potential concern in dust by air is considered to be insignificant for the woodland trespasser and commercial worker due to dense vegetation and high rainfall. Air transport of VOCs is considered insignificant because of their infrequent detection and low concentration in surface and subsurface soil. Inhalation of particulates and VOCs for offsite residents is considered insignificant because the concentrations offsite would be negligible due to the distance. Inhalation of particulates and VOCs may be a potentially complete exposure pathway for future onsite residents and industrial workers.

Transport Mechanism

The principal aquifer at NCTAMS PAC is 800-900 feet bgs. Because of the depth of the principal aquifer, the low to moderate permeability of the intervening soil and rock, and the low mobility and sorption of constituents to soil detected in the perched aquifer below OIS, the groundwater pathway is considered incomplete. Perched groundwater was not identified at the site and therefore the pathway is incomplete.

Potentially Complete


Contaminant Source Rationale

Receptors

Future Use

Inhalation ofParticulates

Direct contact and incidental ingestion with surface soil is potentially complete for woodland trespassers, future residents, and all future onsite workers.

Surface Water

Unsaturated/ Saturated

Zone Transport to Groundwater

Figure 3 Human Health Conceptual Site Model for the OIS

NCTAMS PAC, Wahiawa

Release HistoryContributing

SourcesTransport

Mechanisms Exposure RouteEcological Receptors 1 Rationale

Insignificant

Inhalation may be a potentially complete pathway from fugitive dust generated during dry, windy conditions or during construction or remediation activities. However, the Old Incinerator Site receives high rainfall, is heavily vegetated, and located in a gully where wind-blown dust is unlikely to be generated.

Insignificant

While VOCs may volatilize into soil air spaces and migrate to the soil surface where they may be emitted to the atmosphere, the surface soil depths are expected not to contain VOCs due to volatility of constituents. VOC exposure for terrestrial birds and mammals is considered insignificant in comparison to ingestion exposure.


Terrestrial ecological receptors may be exposed by ingestion of contaminated surface soil during foraging and/or grooming activities.

Insignificant

Dermal exposure by terrestrial birds and mammals is possible, but exposure parameters for these receptors are lacking; therefore, quantitative evaluation of this pathway is not presented. Dermal exposure is considered insignificant in comparison to ingestion


Terrestrial ecological receptors may eat the natural vegetation growing on site and feed on soil invertebrates living on site.

IncompleteInfiltration to subsurface soil is possible after heavy rainfall; however, ecological receptors are not expected to have significant exposure to subsurface soils.

IncompleteInfiltration to subsurface soil is possible after heavy rainfall; however, ecological receptors are not expected to have significant exposure to subsurface soils.

Incomplete Groundwater does not discharge to the surface at the OIS. Terrestrial ecological receptors are not expected to be exposed to groundwater.

Incomplete

Runoff water flows in the gulches in response to precipitation. Water does not persist long enough to support aquatic or benthic communities nor provide a regular drinking water source for terrestrial animals. Groundwater does not discharge to the surface at the Old Incinerator Site. Terrestrial ecological receptors are not expected to be exposed to surface water.

(1) Future conditions are assumed to be the same as current conditions for ecological receptors. No future scenarios are run.

Waste documents and other papers

were destroyed by burning in an

incinerator located near the gulch adjacent to the

Building 6 disposal site. Contamination

appears to be associated with the incinerator ash and the soil in contact with the ash layer.

Surface Soil(0-2 ft bgs)

Windborne Particulates

Inhalation of Fugitive

Particulates

Volatilization Inhalation of VOCs

Direct Contact

Incidental Ingestion of

Soil

Dermal Absorption

Ingestion ofPlants/Animals

(bio-uptake)

Dermal Absorption

Subsurface Soil

Dermal Absorption

Incidental Ingestion

Surface Waters

Runoff and discharge of groundwater

Ingestion

GroundwaterIngestion of

Groundwater

Dermal Absorption

Inhalations of VOCs

Inhalation of VOCs

Bio-uptake

Direct Contact

Inhalation of VOCs

Inhalation of Particulates

Direct Contact

Direct Contact

Figure 4Ecological Conceptual Site Model for the OIS

NCTAMS PAC, Wahiawa


2.7.1 Human Health Screening Risk Assessment

A human health SRA was conducted for OIS to help risk managers evaluate risks associated with exposure at the site and determine whether further action is warranted to protect human health. This section summarizes the human health SRA, the entirety of which is included as Appendix C of the RI Report (Earth Tech 2006). The SRA is the first of three tiers defined by Navy policy for conducting human health risk assessments (DON 2003). The purpose of the Tier 1 SRA is to identify COPCs that may pose undesirable risks to human health. The SRA incorporates all elements that the Navy has identified as necessary for a screening assessment (DON 2003); additionally, it includes elements typical of a Tier 2 assessment to satisfy screening requirements of EPA Region 9. The Tier 1 SRA consists of two parts: (1) Tier 1A, the risk-based screening, in which default residential and industrial exposure assumptions are evaluated, and (2) Tier 1B, a site-specific risk-based evaluation that evaluates potential reuse scenarios. Analytical results from surface soil (0 to 0.5 foot bgs) and subsurface soil (0.5 foot to 12 feet bgs) samples were used to identify the human health COPCs for each exposure medium evaluated in the SRA. All analytes detected in surface soils and subsurface soils were retained as COPCs for the human health SRA. Surface water was not encountered during environmental investigations performed at the OIS and therefore was not evaluated for risk.

Results of the human health SRA are summarized in Table 3.

Table 3: Summary of Human Health Risk Assessment Results for the Old Incinerator Site

Exposure Scenario

Cancer Risk - Including Background

Cancer Risk - Excluding Background

Hazard Index - Including Background

Hazard Index - Excluding Background

RME CTE RME CTE RME CTE RME CTE

Residential - Surface Soil

3 × 10–5 4 × 10–6 4 × 10–7 5 × 10–8 10 1 0.9 0.1

Residential - Subsurface Soil

1 × 10–4 2 × 10–5 1 × 10–4 1 × 10–5 20 2 8 1

Industrial - Surface Soil

8 × 10–6 4 × 10–7 1 × 10–7 5 × 10–9 0.3 0.1 0.05 0.01

Industrial - Subsurface Soil

3 × 10–5 1 × 10–6 3 × 10–5 1 × 10–6 0.7 0.2 0.6 0.1

CTE central tendency exposure RME reasonable maximum exposure

2.7.1.1 SURFACE AND SUBSURFACE SOIL

Incremental lifetime cancer risks and target hazard indices (HIs) for OIS soils reported in this discussion represent results after excluding contributions from background metals concentrations. The incremental lifetime cancer risks associated with exposure to the exposure point concentration (EPC) in surface soil at the OIS for the residential and industrial reasonable maximum exposure (RME) use scenarios were below the 1 × 10–6

The incremental lifetime cancer risks associated with exposure to the EPC in subsurface soil at the OIS for both the residential and industrial RME were estimated as 1 × 10–4 for the residential scenario and 3 × 10–5 for the industrial scenario. Most of this risk is due to arsenic, since it is a site-related COPC. Excluding the contribution from background, site-related non-cancer hazard for subsurface soil for the residential land use is 8 under the RME scenario. Much of this non-cancer hazard is due to exposure to antimony (approximately 28 percent), arsenic (approximately 25 percent), and copper (approximately 20 percent). The non-cancer hazard for subsurface soil for the industrial land use is less than 1.

point of departure. The cumulative non-cancer hazard associated with exposure to the EPC in surface soil was less than the HI point of departure of 1 for the residential and industrial RME scenarios.


2.7.1.2 SURFACE WATER

Surface water was not encountered during environmental investigations performed at the OIS (NEESA 1986, HLA 1989, ANL 1992, Earth Tech 2006), and therefore not evaluated for risk.

2.7.1.3 GROUNDWATER

No perched groundwater was encountered at the OIS, and COPCs were not identified in groundwater samples from the downgradient water supply well that is completed within the deep Wahiawa System aquifer. It was concluded that the groundwater exposure pathway was not complete; therefore, risk from exposure to groundwater was not evaluated.

2.7.2 Human Health SRA Conclusions

After excluding background metals, human health risks/hazards from surface soil exposure at the OIS were concluded to be below target points of departure for all exposure scenarios considered. The risk evaluation results for subsurface soil at the OIS identified incremental lifetime cancer risk that exceeded target points of departure for the residential and industrial receptors under the RME scenario. The greater risk/hazard from exposure to subsurface soil at the OIS is attributable mostly to arsenic, which is present at levels that exceed background concentrations. The human health risk/hazards associated with subsurface soil exposure indicated that mitigation through LUCs or removal action is required for the OIS to protect public health or welfare and the environment from actual or threatened releases of hazardous substances into the environment.

2.7.3 Ecological Screening Risk Assessment

The Tier 1 ecological SRA evaluated risks potentially attributable to chemicals detected in soil at the OIS Site. The SRA is intended to comply with the EPA guidance for Steps 1 and 2 of the 8-step Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessment (EPA 1997) and Tier 1 of the Navy Policy for Conducting Ecological Risk Assessments (DON 1999). The SRA process ends with a scientific management decision point. The full ecological risk assessment (ERA) is presented in Appendix C of the RI Report (Earth Tech 2006).

Designation of chemicals as risk-associated agents was assessed with two lines of evidence.

Exposure Pathway Analysis—Comparison of habitat on site to habitat in the immediate area and the habitat's attractiveness to species that may visit the site.

Ecological Soil Benchmark Concentrations—Comparison of maximum chemical concentrations detected in surface soil to EPA ecological soil screening levels and Oak Ridge National Laboratory direct contact screening levels (based on toxicity to plants and soil invertebrates) and conservative site-specific ecological soil benchmark concentrations based on exposure of small mammals and omnivorous birds to soil contaminants through food-chain ingestion.

2.7.3.1 RESULTS

The ERA conducted during the RI indicated unacceptable risk associated with copper, lead, and zinc in OIS soil. It was also concluded that dioxins may also pose risk to ecological receptors at the OIS, but the risk could not be assessed quantitatively because although dioxins were not detected in the soil samples, the laboratory reporting limits exceeded the screening values.

The Tier 2, Step 3a ERA calculations were based on multi-incremental samples collected at the OIS in November 2006, representing 300 systematic random surface soil sampling locations from across the site. A total of 10 samples, including a duplicate and triplicate sample, were analyzed for


antimony, arsenic, copper, lead, and dioxins. EPCs for the five chemicals of concern were estimated as the mean of the eight decision units.

The exposure and hazard quotient (HQ) calculations based on no-observed-adverse-effect level (NOAEL) toxicity reference values (TRVs) used the same equations presented in the RI ERA. Birds had no HQ values that exceed 1, indicating that a risk of adverse effects from the soil food chain pathway was not likely. Mammals showed a slight HQ exceedance of 1 (HQ = 2 for copper and 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalency), indicating a potential for adverse effects. The exposure and HQ calculations based on lowest-observed-adverse-effect level TRVs indicated that all HQ values for both birds and mammals were less than 1, indicating a low probability of adverse effects for the OIS.

2.7.3.2 ERA CONCLUSIONS

Ecological risks calculated during the RI indicated that copper, lead, and zinc have NOAEL derived HQs of 20 or greater for surface soil at the OIS. However, additional samples collected in November 2006 indicated that all HQ values for both birds and mammals were less than 1.

Birds and mammals were only evaluated for exposure to surface soil through incidental ingestion during foraging and/or grooming activities, ingestion of natural vegetation that grows at the site, and feeding on soil invertebrates that live at the site. Exposure to groundwater, surface water, or subsurface soil was not expected since:

Groundwater does not discharge to the surface at the OIS; Surface water does not persist long enough in the gulches to support aquatic or benthic

communities nor provide a regular drinking water source for terrestrial animals; and Although infiltration of storm water to subsurface soil is possible, exposure to terrestrial

animals (e.g. birds and mammals) is not expected to be significant.

As a result, the low no-effect HQs indicated that surface soil at the OIS does not present an unacceptable risk of adverse effects to bird or mammal populations and need not be considered further for ecological risk. These results indicated that response action is not required at the OIS to protect wildlife receptors.

2.8 RESPONSE ACTION OBJECTIVES Based on the results of the risk evaluations summarized in Section 2.7, a response action is required at the OIS. The response action objectives for the OIS are:

Protect human health and the environment.

Prohibit unauthorized access to the OIS.

Ensure no unauthorized excavation, uncontrolled soil removal, or construction occurs at the OIS.

Provide adequate notice of the contaminated media in the OIS to site users, workers, and any future landowners.

Protect worker safety by ensuring that any authorized entry (i.e., annual inspection) is performed by personnel that are properly trained for hazardous material operations.

Ensure that there is no unauthorized land development or land use at the OIS, including schools, child care facilities, and playgrounds.


Site risks will be mitigated by instituting site controls that limit or eliminate potential routes of exposure to the COPCs in the subsurface soil.

2.9 DESCRIPTION OF ALTERNATIVES To meet requirements of the NCP response action, the Final Feasibility Study (FS) (Earth Tech 2007b) conducted for the OIS preliminarily evaluated a range of response action alternatives based on effectiveness, implementability, and cost (Earth Tech 2007b, DON 2006a). The following alternatives were considered during the initial screening:

No Action (as a baseline for comparison)

LUCs

Capping

Phytoremediation

Electrokinetic Separation

Solidification/Stabilization, In Situ and Ex Situ

Soil Washing

Chemical Extraction

Hot Spot Removal and Disposal and LUCs

Excavation (all contaminated soil) and Disposal

With the exception of the “No Action” alternative, alternatives receiving a “poor” ranking during the initial screening either in effectiveness or implementability were not considered for further evaluation. The four alternatives that were retained for further evaluation included:

Alternative 1: No Action (as a baseline for comparison)

Alternative 2: LUCs

Alternative 3: Hot Spot Removal and Disposal of a CERCLA approved facility with LUCs

Alternative 4: Excavation of all contaminated soil and disposal at a CERCLA approved facility

2.9.1 Description of Alternative Components

The major components and expected outcomes of each alternative are summarized below:

No Action. The “No Action” alternative is not expected to be protective of human health or the environment. Neither human receptors nor ecological receptors are protected from potential exposure to COPCs in site soils. Neither short-term not long-term site risks are addressed by the baseline alternative.

LUCs. Instituting site access control and land use restrictions at the OIS is expected to reduce long-term site risks by limiting the potential of exposure to COPCs in the site soils. Human and ecological receptors would be protected from direct contact with contaminants in subsurface soil by the existing soil cover.

Hot Spot Removal, Disposal, and LUCs. Excavating impacted soils (soils containing elevated levels of arsenic and lead) to remediate a hot spot area within the OIS reduces long-term site risks by


decreasing contaminant mass at the OIS. Approximately 100 cubic yards of soil would be removed. Hot spot removal manages risk by limiting potential exposure to high concentrations of COPCs remaining in site soils. The site is currently stabilized by heavy vegetation. Excavation and disposal of soils significantly increase short-term site risks by handling subsurface soil and exposing COPCs where workers and potentially the public may be exposed. Further, excavation would eliminate the protective stabilization of the vegetative cover, exposing the soils to potentially heavy flood events. Site access controls and land use restrictions manage risk by limiting potential future exposure to COPCs remaining in site soils, and maintaining current stable site conditions.

Excavation (all contaminated soil) and disposal. Excavating all soils containing COPCs at concentrations above residential limits and off-island disposal at a CERCLA approved facility eliminates long term site risks by removing contaminants from the OIS. No further action is required following removal. Excavation and disposal of soils significantly increase short term site risks by handling subsurface soil and exposing COPCs where workers and potentially the public may be exposed.

2.10 COMPARATIVE ANALYSIS OF ALTERNATIVES The four alternatives were subjected to comparative analysis using the NCP evaluation criteria. Each alternative was evaluated against criteria of effectiveness, implementability, and cost using a five-tiered scale (i.e., poor, fair, good, very good, and excellent). Estimated degree of regulator and public acceptance are reflected in the analysis. These criteria are summarized in Table 4.

Table 4: Criteria for Detailed Evaluation of the Response Action Alternatives

Criterion How the Criterion is Applied

Effectiveness Overall protection of human health and the environment

Assesses the ability of an alternative to eliminate, reduce, or control the risks associated with exposure pathways including direct contact, potential migration, and risks to ecosystems.

Short-term effectiveness Assesses the capability of an alternative to protect human health and the environment during implementation of the alternative (the construction, removal, and disposal).

Long-term effectiveness and permanence

Measures the ability of an alternative to permanently protect human health and the environment.

Reduction in toxicity, mobility, or volume of contaminants through treatment

Evaluates the ability of an alternative to permanently or significantly reduce the toxicity, mobility, or volume of the chemicals particularly through treatment.

Compliance with ARARs Evaluates the potential of an alternative to achieve chemical-, location-, and action-specific ARARs.

Implementability Implementability Evaluates the technical feasibility or difficulty of applying the alternative at the site, the

reliability of the technology, the unknowns associated with the alternative, and the need for treatability studies.

Assesses regulatory agency concurrence and the need for permits and waivers. Assesses mobilization needs, the accessibility of equipment, and number of trained

personnel required to complete the alternative. State acceptance Evaluates the likelihood of approval by the State. Community acceptance Assesses the anticipated level of acceptance by the community. Cost Assesses the capital, operation, and maintenance costs of each alternative.

Table 5 presents a summary of the comparative analysis of the three response action alternatives presented in the Final Feasibility Study (Earth Tech 2007b). Each alternative is evaluated against the nine NCP criteria and rated according to the ability of the alternative to achieve response action objectives.


Based on the screening of removal action alternatives, the evaluation and comparative analysis of retained alternatives, and considering the marginal risks present at the site, the recommended alternative is Alternative 2: LUCs to prevent exposure to contaminated soil.

2.11 PRINCIPAL THREAT WASTE The NCP establishes an expectation that treatment will be used to address the principal threats posed by a site wherever practicable. Materials constituting a principal threat waste are source materials with toxicity and mobility characteristics that combine to pose a potential risk several orders of magnitude greater than the risk level that is acceptable for the current or anticipated future land use, given realistic exposure scenarios (EPA 1997). No highly toxic and highly mobile source material remains at the OIS; therefore, no principal threat wastes exist at the OIS.

2.12 SELECTED FINAL REMEDY 2.12.1 Summary of the Rationale for the Selected Final Remedy

The primary objective of the final remedy at the OIS is to prevent exposure to COPCs (i.e., elevated levels of metals and PAHs, as well as dioxins) present in the site soils, thereby minimizing potential risks to human health and the environment. Based on the evaluation of alternatives conducted in the FS and presented in Table 5, LUCs were identified to be effective in meeting the goals of the remedy and therefore selected as the best alternative. LUCs will include warning signage for effective access restriction, deed restrictions to prohibit any future development in the event the OIS is transferred to a non-federal entity, and annual inspections to identify any signs of erosion including exposure of subsurface soil and evidence of unauthorized or inappropriate land use. Five-year reviews will be performed to ensure that LUCs remain effective. Current site conditions, specifically the heavy vegetative cover, have been in place for 40 years with no known erosion problems and have stabilized the soils on the steep slope of the site. The implementation of LUCs, rather than hot spot excavation, will prevent the removal of the dense vegetation and its established root system present at the OIS. This dense vegetation has created a competent surface that provides protection against soil erosion and an additional barrier to deter contact with subsurface soil for both human and ecological receptors. Excavation would eliminate the protective stabilization of the vegetative cover, exposing the soils to potentially heavy flood events. In addition, LUCs provide adequate control of COPCs and effectively control site risk, representing the best balance of the various decision criteria.

Table 5: Detailed Analysis of Remedial Action Alternatives – Old Incinerator Site

Alternative 1. No Action 2.LUCs 3. Hot Spot Excavation/ LUCS 4. Excavation and Disposal

Description No action will be taken to reduce the toxicity, mobility, or volume of contamination. No action will be taken to minimize potential threats that may result from sub-surface soil exposures in the future.

Score Warning signage will be erected for effective access restriction. A base implementation plan or deed restrictions will prohibit any future development of the site to ensure that contaminated soil is not disturbed. Annual inspections will be performed to identify any evidence of erosion including exposure of subsurface soil. Erosional effects identified in the annual inspections will need to be addressed, though no costs were budgeted for estimation purposes. Five-year reviews will be performed to ensure that LUCs remain effective.

Score Hot-spot excavation of soil containing elevated levels of arsenic and lead above industrial PRGs/background concentrations or contributing to site-related risks, from three locations. Excavation at each location covers a circular area with a diameter of 20 feet and depths varying between 6 and 11 feet. Total volume of soil removed is estimated to be 100 cubic yards. Prior to excavation, large trees will be removed from the area. Standard excavation equipment will be used for the excavation effort. Confirmation samples will be collected from each excavation to characterize soil in the excavated area. Excavations will be backfilled with clean soil from Oahu. Excavated soil will be containerized for shipment and disposal at a facility approved to accept CERCLA remediation waste for subsequent landfilling. Excavated areas will be restored. LUCs consisting of a base implementation plan or deed restrictions and annual inspections and reporting will be implemented to ensure that the remaining contaminated soils (below industrial PRGs) are not disturbed or potential routes for exposure are not created by future land use changes. Five-year reviews will be performed to ensure that LUCs remain effective.

Score The alternative involves the excavation of all soils above the residential screening limits and off-island disposal at a CERCLA facility. Following the removal action, the site would be backfilled with clean soil and no further action would be required.

Score

Threshold Criteria Overall Protection of Human Health and Environment

Exposure of human or ecological receptors to contaminants in the subsurface soil may occur and may remain undetected.

Poor (1)

Potential exposure of humans to contaminants in the subsurface soil is minimized by LUCs providing early detection of erosional effects, if any, and taking actions, as necessary. LUCs control site access and prevent future construction activities or development of the site.

Very Good (4)

Potential exposure by humans to contaminants in the subsurface soil is reduced by hot spot excavation. Residual risk remains due to the presence of subsurface soils exceeding residential PRGs. LUCs control site access and prevent future construction activities or development of the site and prevent exposure to contaminated soil.

Excellent (5)

Soil removal eliminates contamination posing unacceptable risks and permits unrestricted land use at the site. Disposal of soils in a secure landfill approved to accept CERCLA waste ensures no subsequent exposure to contaminants occurs at the OIS.

Excellent (5)

Compliance with ARARs and TBCs

Does not comply with all ARARs. Poor (1) Complies with ARARs and TBCs. Excellent (5)

Complies with ARARs and TBC criteria. Excellent (5)

Complies with ARARs and TBC criteria. Excellent (5)

Primary Balancing Criteria Long-term Effectiveness and Permanence

Inadequate to protect human health and the environment. This alternative does not satisfy the NCP preference for treatment.

Poor (1)

LUCs with inspections on an annual basis will ensure long-term effectiveness of this alternative. If necessary, corrective action will be taken to ensure that the exposure risk is manageable. Adequacy and reliability of controls are good. This alternative does not satisfy the NCP preference for treatment.

Good (3)

Some contamination is removed from the site. Residual risk remains due to subsurface soils exceeding residential PRGs. Adequacy and reliability of controls are good. This alternative does not satisfy the NCP preference for treatment.

Very Good (4)

Contamination is removed from the site, thereby eliminating onsite human health and ecological risks. The offsite residual risk of the properly disposed soil is very low due to its placement in an engineered landfill. Alternative is permanent. Adequacy and reliability of controls are excellent. Contaminants may remain untreated. Therefore, this alternative may not satisfy the NCP preference for treatment.

Excellent (5)

Reduction in Toxicity, Mobility, and Volume through Treatment

No reduction in toxicity, mobility, or volume through treatment.

Poor (1)


Poor (1)


Poor (1)

No reduction in toxicity,or volume through treatment. Metals in soil may be stabilized to reduce mobility.

Poor (1)

Short-term Effectiveness

Implementation of alternative will not increase risk to workers, community, or the environment.

Excellent (5)

No unacceptable risk exists under current site conditions and commercial/industrial use. Minimal risk to workers conducting annual inspections and erecting signage around perimeter.

Very Good (4)

Poses short-term risks to workers and the public during excavation and transportation through potential exposure to higher contaminant concentrations in subsurface soil. Disturbance of existing mature vegetation would result in potential for soil erosion.

Fair (2)

Poses short-term risk to workers and public during excavation and transportation through potential exposure to higher contaminant concentrations in subsurface soil Also, steep slopes present a increased safety risk to workers while utilizing excavation and hauling equipment. Disturbance of existing mature vegetation would result in potential for soil erosion.

Fair (2)

Implement-ability No technical feasibility issues with implementation of this alternative. Administrative approval is likely to be difficult.

Good (3)

No technical feasibility issues associated with implementation. Material and equipment for alternative are readily located on-island. No administrative issues associated with implementation.

Excellent (5)

No technical feasibility issues associated with implementation. Material and equipment for this alternative are readily located on-island. No administrative issues associated with implementation. Hot spots are associated with discontinuous layers of ash. Additional effort would be required to further delineate material requiring removal. Material handling required to separate ash layers would be problematic.

Fair (2)

No technical feasibility issues associated with implementation. Excavation of large amounts of material in a steep sloped gulley would require additional road building to allow access to the entire contaminated area. Material and equipment for this alternative are readily located on-island. No administrative issues associated with implementation.

Good (3)

Cost NPV = $0 Excellent (5)

NPV = $247,173 Very Good (4)

NPV = $1,258,239 Poor (1)

NPV = $8,969,210 Poor (1)

Alternative 1. No Action 2.LUCs 3. Hot Spot Excavation/ LUCS 4. Excavation and Disposal

Modifying Criteria Projected

Regulator Acceptancea

Alternative would not likely be accepted since implementation does not result in risk management or risk reduction.

Poor (1)

Regulator approval is expected since the alternative is protective of human health through risk management.

Very Good (4)

Regulator approval is expected since the alternative is protective of human health through risk reduction and risk management.

Very Good (4)

Regulator approval is expected since the alternative is protective of human health through risk reduction and risk management.

Very Good (4)

Projected

Community Acceptancea

Alternative would not likely be accepted since implementation does not result in risk management or risk reduction.

Poor (1)

Community acceptance is expected since the alternative is protective of human health through risk management.

Very Good (4)

Community acceptance is expected since the alternative is protective of human health through risk reduction and risk management.

Very Good (4)

Community acceptance is expected since the alternative is protective of human health through risk reduction and risk management. However, large amounts of waste transport through residential areas may reduce community acceptance.

Good (3)

TOTAL SCORE Poor (19) Very Good (34)

Good (28)

Good (29)

a Typically the regulator and community acceptance criteria are evaluated as the process moves forward based on feedback received during the public and regulatory review processes. For this evaluation, the projected regulator and community acceptance is based on the historical acceptance of these alternatives at similar sites and areas of contamination.


2.12.2 Description of the Selected Final Remedy Components

Based on an evaluation of response action alternatives, the Navy and EPA Region 9, in coordination with EPA Headquarters, and with the concurrence of the DOH, have selected LUCs as the final remedy for the OIS. The elements of the selected final remedy include the following:

LUCs

Five-year reviews

These components are described below:

Land-Use Controls. LUCs will be used to control access to and restrict use of the site to ensure that the impacted soils are not disturbed. LUCs will also ensure potential routes for exposure are not created due to land use changes. LUCs for this site will apply to the land within the site boundaries shown on Figure 2, which represents the 0.14 acres of OIS.

Site access restrictions will prevent unauthorized entry. Land use restrictions will be implemented to prohibit any activity or land modifications (e.g., vegetation clearing, regrading, excavation, landscaping, and construction of structures) that may potentially expose contaminated soil at the OIS.

The Navy is responsible for implementing, maintaining, reporting on, and enforcing LUCs. This may be modified to include another party should the site-specific circumstances warrant it. Although the Navy may later transfer these procedural responsibilities to another party by contract, property transfer agreement, or through other means, the Navy shall retain ultimate responsibility for remedy integrity. The Navy shall implement internal procedures for upholding LUCs by maintaining a database of the LUCs (i.e., Naval Installation Restoration Information Solution).

LUCs will be maintained at the OIS until the concentrations of hazardous substances in the soil are at levels to allow for unrestricted use and exposure. LUCs will then be terminated. A LUC WP has been prepared and submitted (Earth Tech 2008). The LUC WP will be finalized to contain implementation and maintenance actions, including periodic inspections and reporting requirements, notification requirements, specific responsibilities, and details on LUC enforcement. The LUC WP is the Remedial Action Work Plan for implementation of LUCs as the remedy for this site.

Five-Year Reviews. Five-year reviews are required for all CERCLA response actions that leave contaminants in place at concentrations above levels that allow for unlimited land use and restricted exposure. Because chemicals remain in place at such concentrations, five-year reviews will be performed by the Navy to ensure that remedy remains effective to prevent exposure of contaminated soil.

2.12.3 Land Use Control Performance Objectives

Performance objectives for the LUCs being implemented as the final remedy for the OIS are to restrict current and future land use to activities that do not disturb the soil, thereby creating exposure routes to the subsurface soil. Specific LUC performance objectives include the following:

Protect human health and the environment

Prevent unauthorized access to the OIS

Ensure that warning signs remain visible and legible and are maintained in good condition


Ensure no unauthorized excavation, uncontrolled soil removal, drilling, or construction at the OIS

Provide adequate notice of the contaminated media in the OIS to site users, workers, and any future landowners

Ensure that the OIS site is not used for any purpose that violates the objectives of the LUCs by prohibiting the development and use of this area for residential housing, schools, child care centers, playgrounds, retail, commercial, or industrial facilities

Ensure that proper land use restrictions are imposed and maintained at the OIS consistent with the final remedy and that records of these restrictions are maintained in the facility planning records/land use database

2.12.4 Summary of the Estimated Final Remedy Costs

The engineering cost estimate for the selected remedy is $247,173, as provided in Table 6 (Earth Tech 2007b).

Table 6: Cost-Effectiveness Summary and Selection of Recommended Alternatives – OIS

Site Preliminary Alternatives Retained Alternatives NPV Overall Score

Recommended Alternative

OIS No Action LUCs Capping Phytoremediation Electrokinetic Separation Solidification/ Stabilization Soil Washing Chemical Extraction Hot-spot Excavation and

Disposal at a CERCLA Facility and LUCs

Excavation and Disposal at a CERCLA Facility

1. No Action $0 Poor Cost effective and offers long-term effectiveness through risk management.

2. LUCs:

2. LUCs $247,173 Very good

3. Hot-spot Excavation and Disposal at a CERCLA Facility and LUCs

$1,258,239 Good

4. Excavation (all soils above cleanup goals) and Disposal at a CERCLA Facility

$8,969,210 Good

Scores based on scale of

Documents

NAVAL COMPUTER AND TELECOMMUNICATIONS AREA …2.14.5 Location-Specific ARARs/TBC Criteria 38 2.14.6 Action-Specific ARARs/TBC Criteria 39 2.14.7 Cost-Effectiveness of Final Remedy