EMP and Caching


How has it not happened? Perhaps some mad version of submarine launched mutually assured destruction could be part of the reason. Each day, I am grateful that our comfortable, convenient, existence continues unabated.


I have authored a couple of posts regarding EMP with Modern Survival, one had to do with protecting electronics and the other with vulnerabilities of tractor and UTX diesel engines. [Readers – see articles HERE and HERE….Rourke]

Some readers may have read TM 5-690, chapter five on electromagnetic pulse protection, the Metatech report to Oak Ridge, Meta-R-320, “The Early-Time (E1) High-Altitude Electromagnetic Pulse (HEMP) and Its Impact on the U.S. Power Grid,” and of course the ill timed Commission report on EMP. If these are unfamiliar, I highly urge that they be read and studied. Short of full scale unlimited nuclear war, I can think of no singular action that would have such a profound effect upon our way of life. EMP scenarios range from the small scale to worldwide but I strongly suspect that our comfortable, convenient way of existence would change for the worse. We may prepare for a wide range of eventualities, but this is a game changer.

In these modern times, our nation can retaliate immediately against other nation states but we are increasingly entangled in asymmetric warfare where the opposing force is not part of a nation state but part of a religious or ideological movement, located not completely within nation states but spread across continents. The threat of mutually assured destruction means little to such foes, even less when they exist in a third world environment where any access to the electrical grid is sheer luxury. Thankfully, resources required to covertly launch an exo-atmospheric vessel above the continental US and construction of an EMP weapon are complex and apparently beyond the technological competency of our foes. There is no doubt acquisition of such technology is of prime importance to many of our enemies.

Technology used wisely can be a potent force multiplier. Much of that technology uses electronics. Much of which are vulnerable to an EMP. So what kind of items might we wish to protect? The first that comes to mind are small HTs, NVGs, pocket lights, rechargeable batteries such as the Sanyo Eneloop and associated chargers, small solar cells, and longer range, high-powered transceivers. Then there are laser range finders, laser aiming devices, e-readers with comprehensive libraries, electronic weather stations, critical components for our engines…  The list is endless.

Several readers commented that I failed to ground redundantly shielded and protected electronics. Containers smaller than metal US Military medical chests and certainly 20mm ammo boxes DO NOT NEED grounding and probably SHOULD NOT BE GROUNDED! The Meta report referenced above includes a graphic depicting the penetration of EMP through a small opening. Whether the weatherproof gasket in an ammo box offers sufficient gap to permit dangerous EMP is questionable and likely is dependent upon the local field strength. Some have recommended prying out this rubber gasket and replacing it with a screen or other metal filler. Personally, I like the waterproof feature enough to try to overcome its electrical weakness. To do this, I resort to redundant shielding and protect the rubber seal gap by using metalized duct tape such as is used to seal HVAC ducting (not the commonly called duct tape, but the tape with the very silver metalized surface such as is made by 3M and Scotch.

I wrap this tape around the gap where the closed lid meets the body of the box paying particular attention to the latch area. This is very important. Of course the contents must be electrically isolated from the container. I take an item such as a small HT and use an impulse sealer to seal the item in a 7mil bag. I wrap the plastic bag with two orthogonal discrete layers of aluminum foil, and then seal inside another plastic bag. If the humidity is high, I may put a small bag of desiccant in with the radio. I line the ammo box with cardboard and then put the doubly bagged radios inside the box and seal with metalized tape. This ammo box and others are placed inside a cardboard isolated larger ammo box such as a 20mm ammo box. The 20mm ammo box is then sealed with metalized tape and may be electrically isolated inside of a larger medical chest that is likewise sealed with metalized tape. None of these containers are grounded. Successive medical chests are isolated from one another and from contact with the cement floor of my remote bunker with 2×12 boards. Overkill probably but I if I’m going to the effort, I want my radios and other electronics to work. Of course electronics are cached at discrete locations.


There are a lot of reasons to bury valuables including protection from theft and distribution of assets. I try to never concentrate valuable resources within my residence. The things that are important, main battle rifles, binoculars, NVGs, M4s, ammunition, water filters, maps and compasses, precious metals, empty rucks, freeze dried foods, matches and other fire making supplies, winter clothes, boots, and the electronic force multipliers as described previous are all cached. A small bag folded in the top of the container will make it easier to carry retrieved small items.


Land contiguous to national forests is excellent for this purpose as I am loath to hide anything on my own property. Exceptions to this may be made for those with large land holdings or for that solitary weapon cache intended for quick access if forced from the house. Did I mention that I wear cotton gloves when preparing anything for caching, and wipe each individual round of ammunition?


It is hard to improve on the US Military ammunition boxes for the storage of bulk ammunition. I use the impulse sealer to seal a quantity of ammo, say 250 rounds along with desiccant in plastic bags and place these bags in appropriately sized ammunition boxes. If I plan to direct bury individual ammunition boxes, I seal the box in a plastic bag using the impulse sealer and then repeat with another bag. I line the hole with sand, carefully emplace the ammo box and cover with sand, finishing the cover with native soil and surface debris. Recognizing the effect of varying atmospheric pressure on the plastic bags, you should try to minimize free air space between the bags and between the inner bag and ammo box. Of course you could place several ammo boxes in a gamma sealed six gallon plastic drum and then bury the drum.


The very best way I have found to protect weapons is to seal them with desiccant inside a Z Corr bag (https://www.zcorrproducts.com/). Several protected weapons can be stored inside a container such as the Mono Vault that comes in various sizes (http://storeguns.com/mono-vaults/gun-storage and http://www.amazon.com/MONOVAULT-MonoVault-107S/dp/B006J65AOA). I include a small quantity of ammunition impulse sealed in plastic bags inside the Mono Vault along with the weapons. That way, upon retrieval the weapons can be immediately loaded with known good ammunition.


Of course PVC pipe can be used and may be cheaper than the Mono Vault. I have items protected using both methods but the Mono Vault is certainly the very best for repeated access. My caches are buried vertically to minimize magnetic signature with the top being at least one foot below the surface. There is some concern that the foot of a large animal such as an elk or moose may damage the lid of a Mono Vault but by burying a foot or so below the surface minimizes this potential damage. Burying deeper also reduces thermal variance within the tube.


I cannot stress enough the importance of preparing a reference set of directions and list of contents for each cache. These directions should include an itemized list of contents including serial numbers, cache number or other identifier, photographs of the burial area (dropped into a Word document), a hand drawn map showing distances and bearings from discrete temporally invariant landmarks, and date of burial. I’ve been at this for a number of years now. This you should do. I don’t like GPS coordinates but can make a case for doing so. I laminate these reference sets and store in another cache that I am sure to be able to locate. This reference cache tube includes the laminated reference sheets impulse sealed inside a plastic bag, and recovery equipment including a cloth tape measure, compass, mechanical squeeze generator flashlight, gloves, machete, chain saw type cutting blade, and folding shovel. If a cache is to be emptied, I remove the relevant reference sheet from the master cache and destroy after recovery.


There are an endless number of cache scenarios including distracting dummy caches buried above the real cache, caches with deactivated weapons, etc. Anyone burying dangerous items such as weapons should always remember that the cache could be inadvertently discovered. I remember a newspaper account a few years ago about a cache of weapons found alongside an Interstate highway. Pipeline right of way work, water, telephone, and electrical service, civil engineering projects, even erosion, can bring your carefully concealed cache to the light of day. Be careful what you bury and be cognizant that it may be traced back to you. If you cache as a hedge against changing laws, the inadvertently discovered cache can be an arrow pointing right back to you.


The world, indeed our very society, is in a constant state of change. Caches can provide a measure of comfort and security and a real hedge against those changes.



Panhandle Rancher

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6 thoughts on “EMP and Caching”

  1. TY for sharing your wisdom again, @PanhandleRancher…you have given me much to ponder…heck, you always make me think! That’s why I value your posts so much!

  2. One of the reports mentioned above was the Meta R-320. At the end of that report is an appendix titled “E1 HEMP Myths” which puts things into perspective and helps cut through the confusion.

    The “cage within a cage” EMP protection method described above is what we use to stored our extra comms gear. We really don’t have any other electronic gear that is worth protecting from more than lightning/surges.

  3. Wow, Lance, excellent question. You would think that those tucked in on the far side of the Rockies and nestled into the valleys of the Appalachians would be in the radiation shadow of a centrally located detonation. I imagine altitude would have a great deal to do with the angle of attack. Multiple detonation=toast! D.

  4. Excuse my ignorance but aren’t batteries immune to emp’S? I noticed in another post it was said to place batteries in your EMP protected area. Is this incorrect or are they placed there so you have them for the devices?

  5. Thanks to everyone once again for your comments. No doubt refractory metal bearing rock in concentrations such as found in the Mesabi iron ranges of Minnesota might offer some protection but to reiterate, the shield within a shield within a shield is probably the best most cost effective treatment for emp protection. Large lead acid batteries are likely immune to emp; who knows about the smaller batteries such as the 2032 button used in many illuminated reticle rifle telescope sights. I store batteries with chargers and devices for the same reason I store ammo with weapons – mutual availability. Items cached should be relatively immune from theft loss. I want eneloops available when I retrieve my HTs so I impulse seal both these excellent recharables and long life conventional batteries. The last Duracell AAs I purchased had an expiration date of 2023. Surely you would want to check on your cache every decade or so. Any item such as batteries that may leak corrosives are separately enclosed in plastic bags with the impulse sealer. Hope this helps. PH


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