First, the Spaland coaster is being built by Morgan, not Arrow.
Also, if you happened to catch a glimpse of the construction site when they dug-out the holes for the footers, you would have seen lot of water, being pumped out to the bay. 15 feet down, you'd get really wet.
My guess is that, when measuring records for these sort of things, that there is an agreed upon standard as to where the "ground" is, in this case probably average terrain. I doubt there's much more than 10 to 15 feet of rise from the beach up to the highest point (I'm guessing that's the land under the original Soak City slides, which seems to be a bit of a "hill"). In any case, the MF site is already quite low.
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Jeff
Webmaster/Guide to The Point