A former employee of the company that operates the city’s Waimanalo Gulch Sanitary Landfill admits to stealing more than $800,000.

Donna J. Alms, 55, pleaded guilty Friday in U.S. District Court to wire fraud and money laundering. She faces up to 20 years in prison at sentencing in August. She also will have to pay back the money she stole.

Assistant U.S. Attorney Lawrence Tong told U.S. District Judge Derrick K. Watson that between April 2010 and December 2014, Alms, who worked as an operations specialist for Waste Management of Hawaii Inc., caused her employer to overpay a vendor $862,722 from whom she received approximately $680,000 in kickbacks.

Tong said Alms’ responsibilities included working with the vendor that hired temporary laborers, including “litter pickers,” who kept the landfill clear of trash.

He said Alms altered the invoices the unnamed vendor submitted to Waste Management by inflating the number of hours worked by the temporary laborers. She also put herself on the vendor’s payroll and then received the difference in the form of wages, minus health insurance premiums and other standard deductions.

Alms is charged with wire fraud because the vendor collected on its invoices through wire transfers.

No one from the vendor has been charged with any crimes.