PORTLAND — The solar farm planned atop the capped Ocean Avenue landfill can proceed now that the Maine Department of Environmental Protection has approved a revised permit for the project.

“The goal is to complete the solar array before snow flies,” city Sustainability Coordinator Troy Moon said in an email Tuesday about the 660-kilowatt array, which will have more than 2,800 solar panels and was intended to generate enough electricity to power City Hall.

The July 20 approval to modify the landfill closure plan comes about two years after councilors authorized City Manager Jon Jennings to reach an agreement with Revision Energy to build the solar farm on 4.3 acres on top of the 45-acre landfill, which was closed 40 years ago.

Intended to be done concurrently with the solar farm that opened at the capped South Portland landfill last fall, the city project stalled when DEP found conditions at the landfill did not comply with state regulations.

On Tuesday, city spokeswoman Jessica Grondin said remediation has cost $455,000.

On Monday, Brian Beneski of the DEP said problems with the landfill cap and accumulating methane gas made the site unsuitable for building the solar farm. Stormwater infiltration was causing contaminated water to leach at the site, while methane leaks were destroying vegetation needed to protect the cap, according to the DEP.

“We want to protect the landfill infiltration system,” Beneski said. “We just want to make sure the solar panels don’t damage the landfill or prevent maintenance.”

What it meant for the city was the need to improve venting of the methane and to rebuild the cap to a minimum of 24 inches. The first 18 inches needs to be a barrier preventing water from seeping under the cover, and the top six inches must be topsoil to ensure proper drainage.

As it moved forward on capping work last year, the city was also stopped from using soil taken from the State Street Infrastructure Project, since required analytical sampling of that soil had not been done.

City Public Works Director Chris Branch said July 27 the city ultimately bought clay from Shaw Brothers in Gorham to rebuild the cap.

DEP findings also elicited concerns from landfill neighbors, including Sarah Scola and Portland Water District Trustee and former City Council candidate Kim Rich.

“It has all been an incredible education. As local neighbors to the landfill, we were all a tad concerned, but thought everything was up to code,” Rich said Monday.

On Tuesday, Scola said the findings showed better care of the entire site was needed. She and Rich said the city and state were responsive and open.

“Throughout the process, both state and local staff and officials have made themselves available to provide information when requested,” Scola said.

Scola added she was pleased the city has committed to testing groundwater in nearby wells.

The approval requires the city to show the DEP the rest of the landfill is properly regraded and capped, and a comprehensive maintenance plan must also be submitted by Dec. 31, 2019.

Branch said the state will reimburse the city for up to 90 percent of the gas remediation work, but that work was only 30 percent of what the city has spent on compliance.

The most recent agreement between the city and Sunfill North, a Revision Energy subsidiary, dates to Oct. 17, 2017. It had called for the solar farm to begin operating by Dec. 31, 2017.

The contract sets out a 25-year life for the farm, with the city buying electricity generated for more than 10 cents per kilowatt-hour. Moon said the farm is expected to produce 1.12 million kWh. The rates increase to almost 12 cents per kWh in the seventh year of the agreement, when the city has its first option to buy the farm.

Installation costs are paid for by Revision, and the first buyout option is for $1.6 million.

David Harry can be reached at 781-3661 ext. 110 or [email protected]. Follow him on Twitter: @DavidHarry8.

As part of the permit needed to build a solar farm at the Ocean Avenue landfill, the state DEP also required Portland to fence off the entire landfill.

The Ocean Avenue landfill area is also home to wildlife, including this piebald doe, and is frequented by dog walkers.

A contractor carries gravel to the top of the Ocean Avenue landfill, where Portland officials hope a solar farm will be completed this fall. Construction stalled for two years while the landfill was regraded and recapped.