Randolph Center — State officials are investigating how roughly 5,000 gallons of waste was discharged into Penny Brook last week, and whether any action should be taken against Vermont Technical College, where the spill occurred.

A combination of digested manure, composting leachate, brewery waste and water was released into the Randolph Center brook around noon on Wednesday, discoloring the water, according to the Vermont Agency of Natural Resources.

An environmental officer was called to the brook soon after, when a resident noticed the color change, said Kim Greenwood, who heads the state’s Environmental Compliance Division.

Officials are now working to determine whether remediation or action will be needed to prevent further damage, she said.

The spill was caused by a mechanical failure in the system Vermont Technical College uses to deliver fertilizer from its anaerobic digester to agricultural fields, VTC spokeswoman Amanda Chaulk said in a phone interview on Monday.

The digester turns waste — including manure, crops and food processing residuals — into methane that is burned to produce electricity that is sold to Green Mountain Power, according to the school’s website.

The digester can process 15,840 gallons of organic material a day, and the resulting slurry is used as fertilizer.

A series of tubes takes the waste from a holding pond on campus to a spreading system that is then attached to a tractor. It’s a coupling on that delivery system that failed, resulting in fertilizer spilling onto a buffer zone shared with a nearby field, Chaulk said.

Staff members quickly became aware of the failure and turned the system off within four minutes, said Chaulk, who estimated that between 4,000 and 7,000 gallons of waste was spilled. State officials were then called and the brook was running clear by Wednesday evening, she said.

The spill is not believed to have a “big impact” on the environment, but the college recognized it shouldn’t not have happened and takes the event seriously, Chaulk said.

But state investigators said they’re still collecting information on the incident.

As of Friday, the spill was listed on the state’s unpermitted discharge list, which is required in cases where “wastewater, industrial process water, dumping or spills into waters of the state” occur.

The discharge list can be found at http://dec.vermont.gov/watershed/wastewater/discharge-notifications.

Tim Camerato can be reached at tcamerato@vnews.com or 603-727-3223.