Members of the Los Angeles County Sheriff's Department's Industrial Plastic Theft Task Force made the discoveries Wednesday night.
The first location was in South El Monte at a plastics grinding operation under the name Broadway Plastics in the 2000 block of Lee Avenue. Investigators say the products were being stowed, ground and primed to be sold.
The second location was a residence in Lynwood on the 3500 block of Virginia Street. Eight people were arrested and charged with receiving stolen property.