Was the septic company licensed and bonded?

Did the septic company pull a permit?

Yes, licensed and bonded as far as I know. I trusted the general contractor on it.

If by "pull a permit" you mean "get a permit and have inspection by the county", then yes.

You trusted?... you should have been dealing with the septic company directly. You better hope that the septic company was licensed and bonded. Probably was or the county inspector would never have cleared the inspection.

If a permit was pulled and inspected and green tagged by the county then address your questions directly to the septic company. If you don't like the answers contact the county inspector (usually the environmental heath department) and ask them.

If this was done, can environmental services require the contractor / subcontractor to fix it without additional cost to me?

The leach field allows the liquids from the already bologically treated and digested waste to dissipate into the soil. It does not contain waste matter, merely the "clean" products of waste matter treatment. In most areas, it is not considered a health hazard, but local regulations vary. In some areas of the country, biologically broken down sewage is sold for fertilizer.

So, I doubt if you have an actual health issue there, just a smell issue. The health department should have instructed an alternate disposal method of the leach field soil if the soil was considered contaminated as a condition of the permit for the new system. If that wasn't part of their permitting process, then I doubt that it's an issue. But, check with your local code office to be certain if there isn't a local reg that deals with this matter, especially since your septic failed and may not have been working properly to treat your sewage.

As far as the landscape remediation for the septic install, I'd have to ask what was in the contract that you signed? Typically, septic companies do septic installs, and that's it. THey're plumbers, not landscapers. If you want topsoil trucked in and spread over the subsoil revealed by the leach line excavation, then that would be an entirely different expense of yours with an entirely different contractor. However, grass will pretty much grow on any kind of soil, so if you can make it through the cold weather here, then using a broadcast spreader and sprinkler to reseed the area yourself will be the least expensive way of making this cosmetically more to your liking.

When I got my septic tank replaced, there was excess dirt because the new tank was larger. A little black water residue from the (pumped) old tank got into the dirt, some of which was spread around the yard to fill in the ruts left by the truck. One part of the yard, in particular, smelled pretty ripe for a while. It's as biodegradable a contaminant as you're going to find, though, so the smell eventually went away. I don't think you have anything to worry about, as long you keep the kids off it for a while. Also, remember that it doesn't take a lot of septic waste to produce a strong smell.

The contractor warned me that the ground around the new tank was going to settle over time, presumably because they couldn't safely pound it down enough. Sure enough, it has been sinking. Not on top of the tank, but surrounding it. You might also expect to need some touch-up eventually.

I think the concerns in the original post are overblown. In many rural areas, the material removed during routine septic tank pumpouts is simply spread on approved fields for Sun and weather treatment. The odor will soon dissipate. That soil will be good for grass.