A public/private composting venture on Birchswamp Road is in limbo this week, after town officials discovered that an old landfill on which it was to sit was never properly capped.

The Compost Plant, a Providence outfit that collects food scraps from restaurants and converts them into organic compost, had entered into a pilot arrangement with the town to start a composting operation at the site. The firm was preparing to build its operation on top of the town’s old capped landfill, but town officials researching the site discovered that the landfill had never been formally closed, a procedure that included placing a clean “cap” on top of the landfill material.

“Even though a complete closure plan had been approved by DEM, it apparently never took place,” Warren Town Manager Jan Reitsma said. “Until that happens, nothing can really happen” at the site.

Mr. Reitsma said that specifically, the old landfill was supposed to be capped, likely in the early 2000s, but never was. Finishing the capping job will cost upwards of $600,000, he said, and the town is applying for grants to cover the costs.

“The town has a responsibility to do this; it’s a big issue and we realize that,” he said.

He said he does not know if money for the capping was appropriated at the time, and what happened to it if it was.

The discovery of uncapped landfill has also upset the Compost Plant’s plans. Though the firm had been using the site to bag its “Rhody Gold” compost, produced offsite, longer-range goals were to start a comprehensive composting, not just bagging, operation there.

Whether the town is able to work out a new arrangement with The Compost Plant when its landfill work is done remains to be seen. In the meantime, The Compost Plan officials have worked out an arrangement with the owners of the Chace Farm, just down the road, to run their composting operation there on a pilot basis.

The farm land was preserved several years ago with state funds, so the activities allowed there are limited; Mr. Reitsma said it is his understanding that since the composting operation is deemed a temporary arragnemnt, it has been allowed by the state.

“If they had proposed to do food waste composting permanently, it would not have been allowed,” he said.

Mr. Reitsma said the town hopes to complete the landfill capping in one to two years.