The Supreme Court of Victoria this week approved the $23.5 million settlement against the City of Casey and the Environmental Protection Agency (EPA), in a case regarding the leaking of high levels of methane gas from a disused landfill in Cranbourne.

The settlement was negotiated by Slater & Gordon on behalf of Cranbourne property owners whose homes and lives were affected by the gas leaks, which in August 2008 prompted an emergency response including some evacuations.

As part of settlement, the City of Casey has agreed to pay $13.5 million, while the EPA will put forward $10 million.

Slater & Gordon litigation lawyer Manisha Blencowe said the legal research surrounding the class action went back 20 years and included 100,000 documents.

"It has required significant involvement by experts and involved more than a dozen parties," she said.

The settlement will see owners receive an individual settlement between $6,000 and $130,000 based on the relative strength of each owner's claim, including their proximity to the landfill site.

According to Blencowe, members of the class action can expect to receive their payment by July, with final payments in August.