The question is phrased with "there here" because the (admittedly long) answer would be "There is X amount of sand here". In this sentence "there" and "der" aren't locations, whereas "here" and "her" are locations. Another example would be "How much sand is there in the car?" and "Hvor meget sand er der i bilen?". They do make sense without the "there" and "der" but they are equally correct with them, although maybe in slightly different context, which I can't think of right now.
It made sense to me. I had never thought how weird that actually does sound until reading this thread.
Here is the definition of there that is being used:
3 (usu. there is/are) used to indicate the fact or existence of something: there's a restaurant around the corner | there comes a point where you give up.
I promise you, it sounds perfectly normal. (In English anyway -- I can't promise about the Danish.)
When you say it, you don't ever put emphasis on the "there." That would indeed sound weird, in the way you described.
You could say "How much sand is there here," to indicate your amazement at the huge amount of sand. Or you could put more-or-less equal emphasis on the last three words, to pose a matter-of-fact question. Or you could even say "How much sand is there here," to make it sound like you're thinking out loud.