The state Attorney General's office is investigating whether an employee of the company that operates O'ahu's main landfill improperly "spent money on" one or more Health Department officials, according to documents filed in relation to a $2.8 million fine over environmental violations at the Leeward site.

The allegations were raised by the company, Waste Management of Hawai'i, during negotiations with the Health Department to settle the fine, according to a letter from a deputy attorney general to state Sen. Colleen Hanabusa (D-21st District, Nanakuli, Wai'anae).

Waste Management operates the Waimanalo Gulch Landfill in Kahe Valley.

The company "cited certain of its expense records in support of its allegations," the letter says.

"When the Attorney General was informed of Waste Management's allegations, he ordered a complete investigation," the letter says.

The company said it is "cooperating fully" in the probe.

"The Attorney General's office has an investigation, just like the letter says, and since the investigation is open and active, I can't comment" further, said Waste Management spokeswoman Kit Cole.

The Health Department fined the landfill after determining that 18 types of violations had occurred there over two years, and characterized some as "serious."

Waste was piled too high and was not covered with dirt every day, and methane gas generated by the waste was not monitored properly, among other problems, the agency charged nearly one year ago.

Waste Management and the city — which owns the landfill site — are contesting the fine, and Hanabusa has petitioned to become a party to the dispute.

Yesterday, she said she had not been informed of any details about the alleged improper spending cited in the letter. But such allegations bolster her argument that she should be allowed to intervene in the case so that no problems are covered up in a possible settlement, Hanabusa said.

The city is seeking state approval to expand the dump and operate it for at least 15 years after its current permits expire in 2008.

The city and private trash haulers dump about 800 tons of garbage in Waimanalo Gulch per day. Another 600 tons per day includes ash from garbage incinerated at the H-Power electricity generation plant.

The Health Department and Attorney General's office could not be reached for comment late yesterday.

Reach Johnny Brannon at jbrannon@honoluluadvertiser.com.