Yes, IMPEACHES is a Scrabble word!

Letter values in Scrabble US: I 1, M 3, P 3, E 1, A 1, C 3, H 4, E 1, S 1.

Is it a valid word?

IMPEACHES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

challenge the honesty or veracity of
charge (a public official) with an offense or misdemeanor committed while in office
bring an accusation against; level a charge against