Replacement of 12 existing landfill gas wellhead enclosures and supplying one spare enclosure for a total of 13 enclosures. The existing twelve enclosures are at grade in an asphalt parking lot, made of metal, and have corroded to the point of needing replacement. The twelve gas wellheads enclosures are to protect part of the gas extraction system the City maintains. The extraction system is located within an easment on Hospital property. The bidder is to provide, excavation, removal, and diposal of existing enclosures and excavated material, purchase and installation of new enclosures, and repairs to excavated areas and also to provide a minimum of 3 to 6 inches of pea stone to prepare for free draining level base under each enclosure.The successful bidder is responsible for all traffic control, barricades and coordination of work with Hospital staff.