I've worked with lots of veterans/ex-military folks in the environmental field in different capacities. When I thought about it (prompted by the comment on this post), I came up with a bunch of different areas of the environmental biz in which military experience is encouraged (and in some cases required).
1. Entry-level: I want my entry level hires to have some basic undergrad-level science background, because fieldwork is not just an exercise of filling jars and following directions. If something looks off, can you adjust based on a reasonable understanding of the science behind what you're doing? With that said, fieldwork requires you to be self-reliant, to be diligent in completing paperwork and other dull stuff without someone standing over you. And of course, to be ok with doing physical work in bad weather. If you've been in the military, I can safely assume that you'll do just fine with those aspects of the job.
2. Drillers: ex-military folks are very well represented in the drilling industry. I know several drilling managers/owners who specifically seek out ex-military folks as helpers and then as drillers. The reliability and willingness to do hard work I mentioned in #1 are nice, but having someone who knows what to do in an emergency, instinctively, is a huge asset. I've also worked with drillers who are/were firefighters and the same thing applies. When you're in the middle of nowhere, with extremely expensive machinery that may break and do something terrible (or if you have a dumb/clumsy helper), having that ingrained instinct to assess damage/hazards to others and do emergency first aid is key. Also, in my experience, if I have an exceptional driller/helper who is proactive with personal protective equipment (PPE) and safety in general, he's likely an ex-Marine.
3. Project management: I'm not sure if it was a quirk of the organizations I've worked for, but I worked with ton of ex-military logistics types: folks who weren't in combat, but who spent a significant amount of time overseas or in the US running various operations. In the environmental industry, a lot of what we do (and a lot of the cost) is in the logistics.
4. Unexploded ordnance (UXO): military contamination and military explodey bits go hand-in-hand. The US has a huge footprint of areas that were used for target practice, and many of those ranges have passed out of military control. I went trawling through the web for a situation I remembered (I thought in NJ) where a school was built on top of a giant bomb, but my google-foo failed. I found lots of articles like this one, though. Anywhoo, the point is that the environmental biz uses UXO experts in a surprising number of investigations, and all the UXO folks I know are veterans.
5. Business owners: US government (and often state and local) contracts heavily favor veteran-owned (or better yet, service-disabled veteran owned) businesses. Big and small federal contractors are strongly encouraged to subcontract work out to veteran-owned firms. So if you're an entrepreneurial veteran with some experience in or knowledge of a particular facet of the environmental biz, you can get a good head start as a business owner. Keeping that business going and maintaining clients is the hard part.
I know that here in the US, veterans can have a hard time finding post-military employment. I do think that environmental consulting firms are generally veteran-friendly, and that the environmental biz is more likely than others to give a veteran with little industry experience a chance.