NASHVILLE (AP) — A House panel on Tuesday passed a bill that would block Tennessee's Department of Environment and Conservation from regulating how some types of sewage treatment systems are designed and built.

Decentralized wastewater systems are often used where municipal sewers are not available. They work by pumping liquid waste to an on-site treatment facility and then spraying or dripping it onto a field. When the systems are poorly designed, the waste can pool on the surface, contaminate groundwater or run off into nearby streams.

TDEC began working on design standards for the systems in 2018. The bill passed on a voice vote by the House Agriculture and Natural Resources Committee on Tuesday would take away TDEC's power to impose those standards.

"The game is these private businesses want to not be regulated and make their money up front and then pass the problem on to the taxpayers," said Dorie Bolze, president of the Harpeth Conservancy, a nonprofit that works to protect clean water in Tennessee.

Tennessee Wastewater Systems is the company with the largest number of these systems in the state. TDEC data shows that over the past decade, the company has received dozens of notices of violation. Many of the violations show high levels of E. coli, and some of the problems go uncorrected for years.

In Robertson County, TDEC recently ordered the company to pay $98,000 in fines for problems first identified in 2011. According to a March 5 order, a lagoon that is supposed to retain effluent and "provide partial treatment of wastewater through microbiological processes" was not constructed according to plans and instead allows the wastewater to escape directly into the groundwater. The drip field was never constructed.

In a March 27 appeal of the order, the company denies that the lagoon is draining into groundwater and says the drip field is unnecessary because the lagoon is not yet full.

Jeff Risden, the company's registered agent, has defended their systems, saying they are a vast improvement over traditional septic systems and "much safer and environmentally sound than those used by most major cities."

Clean Water Professionals of Kentucky and Tennessee on Monday sent a letter to state Rep. Jason Zachary, the House sponsor of the bill, expressing concern that it "would be dialing back proper regulatory oversight of these systems during the design and construction phase, and without the appropriate oversight and approval, could pose an increased risk to public health."