The Kingsbury Corp. is a big part of Keene’s past. Operating for more than 100 years on the city’s east side, it employed more than 1,000 people at one point, and helped drive the region’s machine-tooling industry.

Though the 22-acre property on Laurel Street now sits pretty much vacant, it’s evident Kingsbury will factor into the area’s future as well. Bought by Manchester businessman Brian Thibeault at foreclosure in 2013, the site is both a headache and an intriguing development opportunity to the city.

As city planners have focused on reinvigorating the Marlboro Street corridor, they’ve sought to extend Victoria Street through from Water Street, bisecting the Kingsbury property. The city has also been trying to ameliorate flooding along Beaver Brook in that area, with an eye toward using the site for retention or other mitigation efforts. The brook runs across the site and, at one point, under the main building itself.

Thibeault has made a habit of being behind on property taxes for the land — to the tune of nearly $1 million recently, including interest and penalties. Periodically, he’s paid enough to keep control of the property, which city officials have been reluctant to claim in lieu of those back taxes.

That’s because the property is polluted; stories abound of barrels and tanks filled with unknown substances being buried on-site through the years from the manufacturing process. Exactly how polluted it is, and what it would cost to clean up enough to use again is the big question. And Thibeault has been reticent about allowing environmental testing on the site that’s needed to determine the extent of ground pollution.

This cat-and-mouse game has been ongoing for several years, but the dynamic may be shifting. Last winter, several city councilors brought the issue to the fore, calling for the city to begin the process of tax deeding — taking the land for taxes. To be sure, it’s a move none of the councilors really wants to complete without knowing what cost the city would become responsible for, and because taking the site would remove the property from the tax rolls.

Thibeault’s answer at one point: Go ahead and take it. But the move has produced some promising results. Thibeault made a good-faith tax payment of $100,000 and recently offered to pay another $470,000 in the coming months. He’s also agreed to allow the environmental testing the city is seeking and is negotiating easements that would allow for the extension of Victoria Street and flood work along Beaver Brook in exchange for lowering his tax debt.

This week, a representative of Thibeault outlined a broad development plan for the site to the city’s planning board. It could include housing, restaurants, state office space and other commercial buildings, plus a pond and other landscaping. The catch: the city’s recent rezoning of the Marlboro Street area would need to be changed to allow for the mixed uses he has planned.

It’s great that after years of relative inaction, the city and Thibeault have reached some agreement on key issues that could result in tax payments being made and progress on development. But any zoning action the city might take ought to still depend on the results of the environmental testing. And the city should seek much more certainty from the developer’s plans so that rezoning doesn’t open the door to some undesirable project. In turn, perhaps officials could agree to freeze the tax status of the property while the testing is done, so Thibeault doesn’t lose ground waiting.

The ideas the developer outlined to the planning board this week are by no means a sure thing. If cleaning up the pollution on the site is very expensive, it could delay or even negate any development. It’s in everyone’s interest for the property to be cleaned up and developed. Exactly what’s done with it remains contingent on how realistic the plans are.