By Zack Briggs, KXLH.

Helena City officials are expected to award a $138,000 bid to Helena Sand and Gravel.

According to city documents, methane gas generated by Centennial Park, Helena's former landfill, is migrating south.

Methane gas levels are said to have exceeded Montana's regulatory limit ever since improvements to the park were made.

Helena city commissioners will consider awarding a bid for the installation of a landfill gas extraction system at Centennial Park during Tuesday's meeting.