Some Maui residents don’t want the county to build a $3.9 million rock embankment to protect a Maui County sewage treatment plant along the shoreline in Kahului.

The state Board of Land and Natural Resources is scheduled to hold a public meeting Friday to consider issuing a conservation district use permit for a 1,100-foot rock revetment to the west of an existing revetment to prevent erosion.

Construction of the revetment with a crest of more than 13 feet is expected to take 12 months. 

Residents, along with the Sierra Club Maui Group, said the county should move the sewage treatment plant to higher ground, in light of flooding from past tsunamis.

"It’s a bad idea (the revetment)," said Lucienne de Naie, conservation chairwoman for the Sierra Club Maui Group. "I really think the county needs some pressure to think of this in a different way."

The state issued a conservation district use permit to the county for the sewage treatment plant in 1972, and it has been serving as the main site for treating wastewater in Central Maui, including Kahului, Wailuku and Paia. 

Tom Cannon, former chairman of the advisory committee to the Maui County General Plan, said a severe tsunami damaging the treatment plant could not only release deadly diseases, but also rupture tanks of toxic chlorine gas stored there, affecting the nearby residential areas in Kahului.

"People would be killed," he said.

A better alternative is to move the sewage treatment plant closer to the county landfill at Puunene, where wastewater sludge is converted into fertilizer and the water could be used for agricultural irrigation, some residents say.

Michael Miyamoto, deputy director of the county Department of Environmental Management, said the administration is carrying out a decision made by the Maui County Council in the late 2000s to keep the sewage treatment plant at Kahului.

Miyamoto said a study done in the early 2000s estimated the cost at $450 million to move the plant. However, opponents say that estimation was old and that a new study by water infrastructure company PERC Corp. projected it would cost $150 million to relocate the plant. 

The county has had conversations with PERC and determined that the cost of moving the sewage treatment plant would be closer to $200 million to $250 million, Miyamoto said.