The odor is back.

The 13 Watchdog team watched Monday, Nov. 28, as a Lowell police officer wrote a third consecutive citation for the Lowell biodigester.

The facility had two failures this past weekend, bringing back the unfortunate -- yet familiar -- smell to the Lowell community. This incident comes just weeks after the Lowell biodigester's operators said they repaired the smell emulating from the plant.

Greg Northrup, the operator of the energy-producing biodigester, told WZZM earlier this month he believed the odors were under control after months of the smell lingering in the community.

Northrup confirmed that the top of the tank of the biodigester ruptured this past weekend, causing the bad smell to reach the streets again. In addition, a valve failed allowing waste to seep out of the facility.

Bushnell Elementary School, just across from the biodigester, had to shut off its fresh air ventilation system as a result of the smell.

Sustainable Partners LLC, Northrup's company that owns the biodigester, spent more than $200,000 for a new odor control system to be put in the facility to ensure the smell did not escape the building. Northrup said he thought the issues were fixed and never expected to face two new obstacles.

"By pumping out the whole tank, we're going to get rid of the source of odor," Northrup said. "We are going to do it as quickly as we can."

The 13 Watchdog team obtained two citations issued by the Lowell Police Department to the operators of the biodigester for the smell. Each civil infraction fines the company $300.

Lowell Police Department citation for the Lowell biodigester -- a $300 fine.

We asked Northrup how he would answer critics who say they need to close the facility.

"Our answer is we need to do the right thing and the responsible thing and operate this facility as an odor-free facility," Northrup said. "We believe it can operate with the work we did last week in terms of the odor control systems because they were working."

Before the most recent failures, Northrup said he was confident he could alleviate the situation.

"We have to be optimistic...we put a large investment in this facility," Northrup said. "We think it's the right facility and we want to get back to the business of making renewable energy."

The 13 Watchdog team obtained dozens of e-mails showing concerns about the smelly plant for more than a year now.

One email shows former executive Tom Russo from Lowell Light and Power wrote that he worried Northrup was "going to set himself up for failure."

Other city leaders wonder whether this $6 million facility will ever be able to comply.

The company has a 20-year deal to sell electricity to the city's utility company.

For now, the biodigester is continuing to repair their failures, as city leaders take a "wait and see" approach.