JOHNSTON, R.I. — What exactly is in the Central Landfill? The question pops up frequently, as issues such as bag bans, incinerators and tipping fees are debated.

An answer is on the way. On July 30, the Rhode Island Resource Recovery Corporation (RIRRC), the manager of the state landfill, approved a $250,000 waste characterization study of the state’s trash. It’s the first such study since 1990.

The study won’t look at what is already buried at the landfill, but will analyze the trash that arrives during a year. Specifically, 280 loads of trash will be picked through to find out who is throwing out what. The study, awarded to DSM Environmental Inc. of Windsor, Vt., takes place as RIRRC is updating it’s 20-year plan.

“It’s costly to do and you have to get some value out of it. The time is now right,” RIRRC executive director Michael OConnell said.

The study will determine the type and amount of waste coming from curbside collection, municipal transfer stations, commercial haulers and out-of-state sources. Currently, 38 of Rhode Island’s 39 cities and towns deliver their waste to the landfill. Tiverton operates its own landfill.

About 800,000 tons of waste are brought to the Central Landfill annually. About 40 percent of all trash and recycling brought there is from municipalities; 60 percent is commercial waste.

Estimates vary on what is typically in the trash. According to the Environmental Protection Agency (EPA), only about 5 percent of organic materials are diverted from the country’s waste stream. This new state data will play into discussions about shrinking the waste stream and other efforts to extend the life of the landfill. In recent years, the General Assembly has addressed issues such as marine debris, product packaging and product stewardship.

The Central Landfill has about 24 years of space remaining, according to RIRRC officials. Low tipping fees — the cost to throw out a ton of trash — are often sited as a major reason why it’s difficult for the state to find cost-effective alternatives to simply throwing away most items. Municipal tipping fees are set by the General Assembly and haven’t raised since 1990. Lawmakers have been reluctant to raise tipping fees out of fear of raising trash bills for municipalities.

These discussions will soon have more substance once everyone knows what’s in the trash, OConnell said. “It was always a question we were asked in everything we ever did.”