MEC Clearance

What is MEC?

MEC clearance is the process of safely clearing an area of munitions of explosive concern. World War II left unexploded ordnance on Guam that may still be dangerous.

MEC clearing is required for 100% of ground disturbance on Andersen Air Force Base. MEC clearance here is conducted primarily before infrastructure improvements on underground utilities and facility construction or renovation.

Both Naval Sea Systems Command OP 5 and Naval Ordnance Safety and Security Instruction 8020.15D dictate when MEC clearance occurs and how it is conducted.

What does MEC mean for me?

The Andersen community is impacted by MEC because of exclusion zones established during MEC clearance. Exclusion zones are areas that are evacuated because of the potential for an explosion. The size of the exclusion zone depends on the type of munitions suspected to be in the area.

On Andersen, exclusions zones vary but are most often either 450 feet or 152 feet in all directions from the area where the earth is being disturbed. All MEC work begins with a 450-foot exclusion until the contractor has dug, scanned and cleared to a preset depth.  At that point, the exclusion zone can be reduced in size to 152 feet and the outside area is no longer off-limits.


Traffic may be rerouted because of MEC exclusion zones. Road blocks and detours are established in a traffic control plan as early as possible before work begins. MEC clearance operations are scheduled to produce the smallest possible impact on the community and often occur at night.


Exclusion zones are only established while MEC clearance is being done. Typical MEC work is done in eight-hour shifts.


When there are pauses in work or non-MEC work is being performed, the exclusion zone will often be lowered to allow cars to pass through. When the area is opened in these scenarios, it is important that it is only for through-traffic as the exclusion zone will be reestablished and work may not resume until the zone is free of unauthorized personnel.


Traffic control plans and MEC schedules may be found here up to one week prior to the closure.

Explosive Operations should be clearly marked with appropriate signage. If you encounter a roadblock, please do not attempt to walk past and into the exclusion zone. Facilities and residences within the exclusion zone will be closed and security will be present to escort unauthorized personnel out of the closed area. If security is not present, a sign will be posted with contact information to enter the exclusion zone should you have a need to enter the area.

Remaining within or entering an exclusion zone will result in work stoppage and can cost the government tens of thousands of taxpayer dollars in delays. MEC clearance for the area will then be rescheduled and will affect the area again at a later date.

Who conducts MEC and how do they do it?

MEC clearance is performed by registered, licensed contractors that specialize in hazard removal such as MEC or UXO’s.  Experienced personnel, often former military Explosive Ordnance Disposal technicians or those who have attended a Department of Defense Explosive Safety Board approved school, oversee the process and perform the scanning of soil as digging occurs.

A metal detector is used to scan the ground as the contractors excavate in predetermined increments.  If anything is detected, they will investigate it, remove it, and rescan before proceeding. Soil that has been cleared is separated and inspected by a government agent to ensure compliance.


Is MEC clearance safe?


While it is important to stay out of exclusion zone, MEC clearance is designed to reduce safety risks as much as possible. Explosions are the primary safety concern surrounding MEC. Staying out of the exclusion zone, to include buildings inside the area, is the best way to reduce the risks presented by MEC clearance.


At the time of this factsheet’s publishing July 18, 2017, Andersen has a track record of no explosions due to MEC clearance and its associated construction.


How will I know if MEC clearance is happening near my home or place of work?

The easiest way to stay in the loop for area and building closures is to check the Andersen Air Force Base, Guam Facebook page Construction Closure Notice photo album or check your government email for construction closure notices. 

MEC closures will typically be coordinated with affected parties a week before work with special consideration to lodging and housing facilities.  Once all parties have been coordinated with, project managers will then reach out their constituents and inform them of any restrictions to their workspace or living facility. 

Notices are placed on or near the entrances of buildings that will be affected by an exclusion zone. Notices are posted typically two weeks in advance if affecting lodging or housing.

The presence of roadblocks, barriers or cones may also indicate that the area beyond is unsafe to enter. Road blocks are accompanied by signs with contact information or security personnel who can provide more information.

For Questions relating to MEC and exclusion zones please contact:

36th Civil Engineer Squadron Customer Service


Contact the POC listed on the area closure notification here for the project in question.