The Walden Woods Project is offering the town of Concord $2.8 million to permanently protect nearly 35 acres of land at the former landfill, a location considered to be a key part of the ecosystem once studied by Henry David Thoreau.

The landfill is capped and has not been used for years but the town still uses the site for leaf composting and snow disposal. Town officials are also interested in putting a large-scale solar installation there to generate energy for the municipal light department.

The proposal, which calls for the Walden Woods Project to pay the town in exchange for a conservation restriction, was originally scheduled to go before voters at Town Meeting last week but was tabled.

Officials say the two sides need more time to answer questions such as whether the composting can be moved and how many solar panels Walden Woods will allow in the conservation restriction. The town would retain ownership of the land.

“It’s a delay, not the end of this effort,’’ said Kathi Anderson, executive director of the Lincoln-based Walden Woods Project. “We made great progress but we need more time.”

Jeffrey Wieand, a member of the Board of Selectmen, said it could be a great opportunity for Concord to generate income...