75$ 6-handed mtt: Is river a mandatory raise?

[memento_mori]

only played like 20 hands so far, but it's clear that villian is a weak player who limps too many hands.
I thought about betting turn, but decided to call/bet most river card instead (is that an ok line on such a dry board?). But for some reason the 8 on the river gets my spidersense tingling! Do you bet river/turn, and if yes how much?

Full Tilt Poker, NL Hold'em Tournament, 15/30 Blinds, 6 Players
LegoPoker Hand History Converter

UTG: 3,060
Hero (MP): 2,910
CO: 2,805
BTN: 2,685
SB: 2,985
BB: 3,555

Pre-Flop: (45) A[img]/images/graemlins/spade.gif[/img] T[img]/images/graemlins/heart.gif[/img] dealt to Hero (MP)
UTG folds, <font color="red">Hero raises to 90</font>, CO calls 90, 2 folds, BB calls 60

Flop: (285) 7[img]/images/graemlins/diamond.gif[/img] 5[img]/images/graemlins/club.gif[/img] T[img]/images/graemlins/spade.gif[/img] (3 Players)
<font color="red">BB bets 150</font>, <font color="red">Hero raises to 450</font>, CO folds, BB calls 300

Turn: (1,185) K[img]/images/graemlins/diamond.gif[/img] (2 Players)
BB checks, Hero checks

River: (1,185) 8[img]/images/graemlins/club.gif[/img] (2 Players)
BB checks, Hero checks