You are looking for the hidden purple bison tube that Superkatze gave me, because I left all my caching supplies in my car at home. BYOP.
I was out with Superkatze, Betweenhereandthere and BBLC on a long, fun caching day (we called ourselves da 'BoMBS'!) We were working on completing a couple challenges, and we found ourselves in Georgetown. The girls just laughed when I saw the tower, and were nice enough to lend me a bison tube and take me over there so I could place it. Happy Hunting!
Thanks, ladies!