Being most familiar with the South Yorkshire coalfields (of times past, THAAAAATTTTCCCHHHHHHHEEEEERRRRRRR!!!!!!) one of the (many[1]) places where people regularly used to go underground and dig tunnels, I suppose I tend to put a Barnsley accent on them, personally.
[1] Durham, South Wales, the area around Coalbrookdale (surprisingly!) are others in the UK, with Pittsburgh entering my consciousness as the most obvious Left Pondian example, and beyond coal there's the like of the eponymouslt known Kimberley deposits in ZA, and I suspect Chile (as a whole, because, to be honest, I have very little subregional knowledge of that country) has been very recently associated with miners, also, but I bet any attempt to try a Chilean accent would be as close to Mexican as anywhere else...
Living just outside Pittsburgh, my first thought when I read this was :"Oh, come on, really?" Then I started trying to refute it. And I have come to the forlorn conclusion that my hometown is basically a mountainhome. 'The Monongahela is composed mainly of sandstone, limestone, dolomite, and coal.' The coal is the highest quality in the nation for making steel. Sixty years ago, we were pushing over thirty percent of the world's steel. For a century, entire families worked in the mills, as we turned the sky and snow black with ash, while we pulled in the dregs of Europe for more and more raw labor. Now, the steel is gone to China, and all that is left is a regional dialect spoken dahntahn and in the surrounding counties, and nowhere else in the world, a social scene built around beer and football (substituted for goblin slaughter), and mullets, as few humans can grow a proper dwarven beard, while we've thrown our out-going migrants all over the known world.
So if yinzguys want ta imagine your dorfs as Picksburghers, well, it fits.