Naval Facilities Engineering Command: Marine Corps Base Hawaii - Hangar Environmental Assessment Draft Revised

Key Chapter Title List

1. Executive Summary: Proposed Action, Purpose, Need, and Alternatives
2. Purpose and Need for the Proposed Action
3. Description of the Proposed Action and Alternatives
4. Affected Environment and Environmental Consequences Analysis
5. Cumulative Impact Analysis
6. Summary and Conclusion of Impacts for the Proposed Action and Alternatives
7. Consistency with Federal Policies and Executive Orders
8. List of Consulting and Coordinating Agencies
9. References
10. Appendix: Public Comments and Responses

Document Introduction

This Environmental Assessment (EA) is led by the U.S. Naval Facilities Engineering Systems Command (NAVFAC) Pacific. It aims to conduct a comprehensive review of the potential environmental impacts associated with the construction of a C-40A aircraft maintenance hangar and related apron at Marine Corps Base Hawaii (MCBH) Kaneohe Bay, Oahu, in accordance with the National Environmental Policy Act (NEPA) and its implementing regulations. The core background is that Fleet Logistics Support Squadron (VR) 51 of the Naval Air Reserve replaced its older C-20G aircraft with the more advanced C-40A in 2019. However, the existing Hangar 104 is insufficient in height to accommodate the new aircraft for indoor maintenance and storm protection. Therefore, new facilities meeting the requirements are necessary to fulfill its mission needs.

The report provides a detailed analysis and comparison of two action alternatives and a No Action Alternative. The preferred alternative is the demolition and reconstruction of the existing Hangar 104 at its current site. The other alternative involves constructing a new hangar on a semi-vacant parcel within the base known as Greenfield. The site selection process rigorously followed criteria including location within the MCBH airfield area, sufficient and aviation-compatible land, and meeting runway and safety requirements. The report excluded the feasibility of several other locations, such as renovating the existing hangar, using the West Ramp area, surrounding road sites, or relocating to other military or civilian airfields like Barber's Point or Joint Base Pearl Harbor-Hickam, providing reasons for their exclusion.

This assessment delves into the potential direct and indirect impacts on eight core resource areas. The analysis indicates that regarding air quality, emissions from both alternatives during construction would be below de minimis thresholds, and C-40A operations are not expected to significantly increase emissions or affect local air quality standards. For water resources, through the implementation of Best Management Practices (BMPs) and Low Impact Development (LID) techniques, impacts on groundwater, surface water, and wetlands are anticipated to be minimal. Concerning biological resources, the report cites the results of a Biological Assessment submitted to the U.S. Fish and Wildlife Service, concluding that with a suite of protective measures, impacts on any special status species would be minor to non-existent. However, regarding cultural resources, the preferred alternative will have an adverse effect on historic resources as it requires the demolition of Hangar 104, which is a contributing element to the Kaneohe Bay Naval Air Station Aviation Historic District. The Navy is consulting with the State Historic Preservation Officer (SHPO), among others, to develop a Memorandum of Agreement (MOA) for mitigation measures. For infrastructure, noise, hazardous materials and waste, and natural hazards and resilience, the report concludes that impacts are below significant levels or can be mitigated through standard measures.

The report also includes a cumulative impact analysis, considering this project in conjunction with other ongoing or planned projects within the base (such as the basing of MQ-9 and KC-130J squadrons, barracks modernization, wastewater treatment plant upgrades, etc.) to assess their combined effects. The final conclusion is that implementing either action alternative would not result in significant adverse environmental impacts. The report further demonstrates that the proposed action complies with the requirements of multiple federal laws and related executive orders, including the National Historic Preservation Act (NHPA), Clean Water Act (CWA), Clean Air Act (CAA), and Endangered Species Act (ESA). This revised draft has been updated based on public comments received in 2023 and will undergo another formal public comment period to ensure transparency and comprehensiveness in the decision-making process.