You state that it is a patented mining claim and that the previous owner told you it is under federal jurisdiction. One of those is incorrect. The federal government no longer has jurisdiction after a patent has been issued (as long as it has not been vacated). Here is the link to the
Clear Creek County Building Department, which contains several FAQs you may find informative about obtaining a building permit. I won't comment on what they regard as appropriate for an individual waste disposal system.
Assuming the land was patented as a "mining claim" the patent will include the mineral rights. You need to read through your deed to make sure that you acquired both the surficial and mineral estate. They can be sold separately. If you purchased a patented mining claim, you will be assessed property taxes by the Clear Creek Assessor. Ask your friend what he was paying. Otherwise, you can use the
Clear Creek County GIS Map and search on the mining claim name or your name. If there are more than one entry, select the one you are interested in viewing. There is a choice to, "View Assessor Record", which will include among other things the annual property taxes. Otherwise, expect a letter from the Clear Creek Assessor in the not too distant future.