ORDNANCE STORAGE AND TREATMENT FACILITIES

INTRODUCTION
The Department of the Navy has prepared this fact sheet to familiarize the community with the proposed plan to continue the onsite storage and thermal treatment of Munitions and Explosives of Concern (MEC) recovered from Mare Island sites. The fact sheet will:

• Explain why there is a continuing need for a MEC storage
  and treatment capability on Mare Island

• Compare various treatment options and their potential
  impacts to the environment

• Describe the process by which the most acceptable option
  will be selected

The continuation of operations is contingent on regulatory agency approval and community acceptance of the Engineering Evaluation & Cost Analysis/Removal Action Workplan (EECA/RAW), a document that details the proposed activities.

MARE ISLAND ORDNANCE HISTORY
What is ordnance and MEC?
Ordnance is the general term used to describe military munitions. Munitions and Explosives of Concern (MEC) are those munitions that, throughout the history of the Mare Island Naval Shipyard (MINS), have been discarded, buried or otherwise disposed of on the property. Navy ordnance manufacturing, handling, storage, and disposal activities were conducted at Mare Island from 1857 through 1972. As a result, discarded MEC material was deposited in several areas of the MINS facility.

The Navy has removed much of the Mare Island MEC at the six major areas of concern by completing a series of removal actions since 1995. The majority of MEC items that were located and removed were small arms rounds (rifle, pistol, and shotgun cartridges having no high explosive components) that dating from the Civil War through the Korean War. A much smaller number of 20 millimeter (mm) and 40 mm anti-aircraft rounds were also removed, along with an even smaller number of larger projectiles. Approximately 10,000 pounds of MEC material (including the combined weight of explosives and associated

(including the combined weight of explosives and associated metallic components such as cartridge cases, projectile bodies, etc.) was recovered. The recovered material was temporarily stored in the aboveground ordnance storage magazine shown in Figure 1. The storage and ultimate disposal of MEC through thermal treatment was approved by the Department of Defense Explosives Safety Board (DDESB) in 1994 to support the Mare Island MEC removal efforts. The thermal treatment of recovered MEC took place at a treatment facility, shown in Figure 2, located in a remote area of Mare Island adjacent to Dredge Pond 7. Treatment operations were performed there between 1996 and 2000 using the processes of open burning and open detonation to destroy energetic material. The process of open detonation involves placing commercial explosives with the recovered MEC, covering it with several feet of sand to minimize fragmentation and noise, and then detonating it to destroy all explosive material. The Navy has protected the public from blast and fragmentation hazards and minimized the impact of noise by implementing the following measures: 

• Minimizing the quantity of explosives used per shot

• Restricting access into the 1,250 foot explosive safety arc maintained around the detonation site

• Adhering to stringent safety and operating constraints

CURRENT STATUS OF MEC FACILITIES
The Navy and regulatory agencies concluded in 1995 that operation of the MEC storage and treatment facilities was a safe and efficient treatment option and would have no significant effect on the environment. However, open detonation treatment operations were halted in 2000 in order to provide additional documentation and review of the treatment facilities.

How often will MEC be treated at Mare Island?
A total of 29 disposal events, each typically consisting of 1 to 6 detonations, were conducted by the Navy between 1996 and 2000. The events were performed in accordance with approved work documents, with favorable community acceptance, and with no significant negative effects on the environment. It is estimated that no more than two (2) additional treatment events per year will be required. The Navy estimates that only a small quantity of additional MEC material, less than 10% of that already treated at the treatment facility, will be recovered in the remaining suspect areas of Mare Island. The first event will treat the small quantity of MEC currently stored since treatment operations were halted in late 2000. Additional events may be required if a significant quantity of MEC is discovered during future removal actions.

PROPOSED MEC TREATMENT OPTIONS
Five potential treatment options were evaluated in the EE/CA:

1. No action

2. Transportation for offsite disposal

3. Onsite treatment (blast chamber only)

4. Onsite treatment (open detonation only)

5. Onsite treatment (open detonation/blast chamber combination)

What is a blast chamber?
The blast chamber shown in Figure 3 is a large trailer mounted unit that contains the blast, fragments, and gases generated by the detonation of small quantities of explosives. The blast chamber is approved by the Department of Defense and has been successfully used at other sites, including Tourtelot in Benecia, where open detonation is not practicable due to adjacent residential housing. Although presenting the least impact to the environment, the use of the blast chamber as Option 1 is extremely costly when only a few items are treated. Options 1 and 2 were eliminated since they are not protective of human health and the environment. Potentially unstable MEC cannot be indefinitely stored and should not be transported over public highways due to safety concerns

What option was selected?
Option 5 was selected from the remaining options as the optimum blend of effectiveness, implementability, and cost. Continued operation of the treatment and storage facilities will comply with all applicable or relevant and appropriate requirements (ARARs). The estimated operating timeframe for the MEC storage and treatment facilities is five years. Magazine A180 will continue to be used for the temporary storage of

recovered MEC pending treatment. Recovered material may be stored for period of time not to exceed 180 days before treatment. Small arms ammunition, which does not represent an explosive hazard, will be transported to an authorized offsite disposal facility. The blast chamber will be utilized whenever a sufficient quantity of MEC has been accumulated to make its use cost effective. Open detonation, a continuation of past treatment practices, will be utilized for items which exceed the limited capacity of the blast chamber, or when only a small number of items have been accumulated in the allowed storage period. The Navy will take appropriate action to assess and potentially remediate the facilities when their use is no longer required.
  

SUMMARY
The Navy proposes to continue the temporary storage and thermal treatment of Mare Island ordnance material utilizing a combination of open detonation and blast chamber. This storage and treatment capability is necessary to safely dispose of MEC material recovered during the remediation and redevelopment of Mare Island property