City sanitation workers cleared a 12-inch sewage pipe clogged by roots that discharged an estimated 7,450 gallons of untreated wastewater from a manhole into Kalihi Stream late Saturday morning.

The state Clean Water Branch later reported a 1,500-gallon discharge at the same spot. That happened just after 4 p.m. and stopped just after 5 p.m., the state said in an email.

The Department of Environmental Services responded to a call at 1817 Alu Street at about 11:13 a.m., a department spokesman said. The site was secured at 1:42 p.m., he said.

The department is in the process of cleaning, disinfecting and deodorizing the affected area near the overflow. Warning signs have been posted and water sampling has begun.

The public is advised to stay out of the waterway until warning signs are taken down.