Hartley, the smallest player on the park but the one with possibly the biggest heart, was thrilled to grab the opening try after his forwards bunted West off their own scum ball.
"It was always going to be pretty tight against West - it was when we played them on Sunday too (Te Puke won 10-7)," said Hartley, who was involved last year when Te Puke finished third.
With fullback Josh Buckton, Waaka and midfielder Jaevyn Mohi threatening , it was first-five Coby Miln who set up Te Puke's second with a superbly-weighted kick that Adrian latched onto.
De Koster threatened Te Puke's line a couple of times in the first half and bullocked over to cut the gap, but that was one of West's few chances after the break as Waaka crashed over out wide after an initial Buckton thrust.
Last year's champions Rotorua Maroon earned some consolation for being bundled out by Te Puke in the semifinals They pipped beat Tauranga East 17-12 to finish third.
Te Puke co-coach Bruce Jepsen, in charge when the subunion went back-to-back in 1999 and 2000, said while the tries went to the backs it was the forwards to muscled up under West's hour-long onslaught.
"We've got a couple of sharp backs and from where this team started to where we are now it a totally different level," Jepsen, who shared coaching duties with former Steamers halfback Rameka Poihipi, said.
It's been a tough 12 months for the Te Puke township, with their cash cow gold kiwifruit crop decimated by PSA, and Jepsen said it was nice to be able to put a smile on a few faces.
"You only needed to look around when we were doing the (post-match) haka to see what it means. It's the only time all the clubs in the town combine together, and we're the only remaining team at tournament still representing the old subunion colours by wearing red and black.
"We're not one of the bigger subunions, probably sixth in size in teams of players to select from, with eight feeder schools, although only one's an intermediate. That's nothing compared to the likes of Tauranga Intermediate, Whare Wananga or Katikati, but the rugby we've seen from these boys this last week demands a shot at the Bay of Plenty (Roller Mills) team."
Tai Mitchell finals:
Championship final: Te Puke 15 (Levi Hartley, Dane Adrian, Te Marino Waaka tries) Tauranga West 5 (Joshua de Koster try). Halftime: 10-0.
For third: Rotorua Maroon 17 Tauranga East 12. HT: 7-7
For fifth: Opotiki 12 Rotorua Gold 12. HT: 12-5 Opotiki
For seventh: Galatea 43 Rangitaiki 7. HT: 12-7
For ninth: Whakatane 5 Apanui 5. HT: 5-5.