DoD, DoN, USMC Policy

• DoD Directive 4715.11 Environmental and Explosives Safety Management on Operational Ranges within the United States
• DoD Instruction 4715.14 Operational Range Assessments.
• Range Environmental Vulnerability Assessment, MCAS Miramar (March 2009)
• 5-Year Review Range Environmental Vulnerability Assessment, MCAS Miramar (June 2013) 

This report presents the assessment results for the operational ranges at Marine Corps Air Station (MCAS) Miramar, San Diego, California. This report is the first comprehensive report on MC associated with the operational ranges at MCAS Miramar and serves as the baseline of environmental conditions and potential vulnerabilities of the operational ranges. Subsequent vulnerability assessments will be conducted on operational ranges at MCAS Miramar on a five-year cycle or when significant changes are made to existing ranges that potentially affect the determinations made during this baseline assessment, as described in the REVA Reference Manual. Final Range Environmental Vulnerability Assessment for Marine Corps Air Station Miramar

MCAS Miramar is the Marine Corps’ primary West Coast air station, comprising approximately
23,065 acres of land. The installation is located 13 miles north of downtown San Diego. The
mission of MCAS Miramar is to maintain and operate facilities and provide services and material
to support the Third Marine Aircraft Wing (3rd MAW) and other tenant organizations. The
mission of the 3rd MAW, the station’s primary tenant, is to provide combat-ready, expeditionary
aviation forces capable of short-notice, worldwide deployment to Marine Air Ground Task Force,
fleet, and unified commanders (MCAS Miramar, 2011a). All operational ranges at MCAS
Miramar are located in East Miramar and consist of five training areas used for maneuver and
land navigation training, nine small arms ranges (SARs) for weapon proficiency training, and one
explosive ordnance disposal (EOD) training range used for training and emergency destruction of
ordnance. There are no high explosive (HE) fixed training ranges or impact areas currently
located at MCAS Miramar.

The undeveloped terrain in East Miramar, part of the Peninsular Range physiographic province, is
characterized by steep, rugged hills separated by deep alluvial valleys that typically are dry
throughout the majority of the year. There are no perennial water features within MCAS
Miramar, although numerous ephemeral drainages may be found throughout the installation and,
in particular, in East Miramar. The installation receives an average of approximately 10 inches of
precipitation per year. During a significant rainfall event, water flows into the main drainage
channels of a number of subwatersheds present within MCAS Miramar. Water eventually flows
off the installation to the south and southwest. Ephemeral ponding may occur in hummocky
areas underlain by a shallow hardpan that restricts infiltration. This may lead to the creation of
vernal pools, which are ecological habitat areas that can support rare, threatened, and endangered
flora and fauna.

Erosion and subsequent transport of MC via surface water runoff through the West Sycamore
Canyon subwatershed is the primary transport mechanism at MCAS Miramar, despite the limited
precipitation at the installation. Leaching to groundwater and subsequent groundwater flow
beneath the range footprint is likely limited by relatively high evaporation rates, the presence of a
shallow hardpan layer, and the deep depth to groundwater. Based on initial analysis, MC may be
transported via surface water beyond the installation boundary and potentially can recharge the
San Diego River Valley groundwater basin located south of the East Miramar installation
boundary. This groundwater basin is a potential public water supply source; therefore, additional
analysis was conducted. Results are detailed in the report.