He established Chapple Research, a consultancy firm, to provide the local community, authorities and industries with environmental and social impact information and advice.

He has also participated in campaigns for the protection of the Murujuga or Burrup Peninsula and the surrounding Dampier Archipelago from encroaching industrial and processing developments, and against uranium mining, uranium ore transportation and nuclear waste storage in Western Australia and in particular the proposed Pangea international nuclear waste dump, having served as the co-ordinator of the Anti-Nuclear Alliance of Western Australia.

He is also an advocate for the introduction of limited voluntary euthanasia, having introduced bills to legalise the act in state parliament in 2002 and 2009 which were both defeated.

Chapple served as a member of the Department of Minerals and Energy's Minerals Environmental Liaison Committee (MELC) and on the state government's mining industries annual "Golden Gecko Environmental Excellence Award" program, as a conservation representative on the technical review and assessment panel.

Before entering parliament, Chapple worked as a research officer for Greens MLC Giz Watson.