Heavy rains Tuesday led to the discovery that a paint additive had been improperly disposed of in a trash bin on Forsyth County property.Fire Capt. Jason Shivers said firefighters at Fire Station 4 on Canton Highway noticed a blue stream flowing from the container. Apparently, a rusty, 5-gallon can containing the substance had fallen over. When mixed with the rain, the concentrated dye flowed west along the road and into a nearby retention pond.It was not clear who left the can in the trash bin or how long it had been there.Shivers said the department's hazardous materials unit and employees from the station tracked the liquid and made sure it didn't spread farther."They found this retention pond where it was collecting and we were able to get the overflow pipe blocked before the retention pond filled with rainwater and risked overflowing out of the pond," Shivers said.