KAILUA — The city and state are investigating a complaint of an alleged illegal dumping of construction debris in an environmentally sensitive area near Maunawili Stream that flows through Kawai Nui marsh.

Carroll Cox, with EnviroWatch, said he received a call about a dump truck dropping off construction material at 801 Auloa Road last Wednesday and on other days. Cox said he's found city and state records in which the owner of the property, who lives on the Mainland, was cited for similar activities as far back as 1999.

The property is being rented to a rock wall builder, said Cox, after visiting the site and taking pictures of the material.

"My concern is there's painted cement and it looks old and flaky, which raises concerns for lead-based paint that poses an environmental risk," he said. "I also saw mastic, which might contain asbestos. The location is right on the Maunawili Stream."

City and state officials said they sent investigators to the site yesterday and need to research their records further.

Steven Chang, with the state Department of Health, said the city and the state are encouraging the reuse of old building material, but contractors must be careful when they process it.

"Our main concern is that it's clean concrete," said Chang, with the solid and hazardous waste branch. "It shouldn't have any lead-based paint."

Chang said the dumping may be legitimate. Old concrete can be used in rock walls or as foundation, but it must be in pieces of about 3 inches and with no contaminates on it, he said.

Cox said given the property owner's record of violations, he will ask for prosecution and excavation of the entire area.

Chuck Burrows, who with hundreds of others has been working to restore the marsh, said the city should demand removal of the materials and any buried items at the owner's expense.

"Any potential contamination of Maunawili Stream from illegal dumping and nonsource pollution will affect our ongoing and future ecological and cultural restoration plans for Kawai Nui Marsh," Burrows said.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com.