March 8, 2011 -- Heavy rain on Sunday contributed to a release into the Long Island Sound of thousands of small white plastic disks from the Westchester County Wastewater Treatment Plant in Mamaroneck.

The disks have washed up on shore from Rye to New Rochelle.

The county's Department of Environmental Facilities is hiring a contractor to retrieve as many of them as possible. The disks, used at the Mamaroneck WWTP to help clean wastewater, are made of HDPE (high density polyethylene). HDPE is a non-toxic plastic that is used in every-day storage of food items. For example, it is the same plastic commonly used for making milk containers.

Thomas J. Lauro, commissioner of the county's Department of Environmental Facilities, said that the plant is under construction, with two of the six aeration tanks being upgraded for advanced wastewater treatment. The disks escaped from one of the tanks during startup of the process. The disks are used in the process of removing nitrogen from the wastewater to prevent hypoxia (inadequate oxygen) in the Sound.

Dr. Cheryl Archbald, acting commissioner of health, said that the disks pose no health risks to the public. Residents who find the disks on their property can throw them in the garbage. As with any debris, it is recommended that people use gloves or wash their hands after handling the disks.

The county has already retrieved thousands of the disks, which are white, about the size of a quarter and resemble a wagon wheel.