Microfloc was the name given to a revolutionary filtration process originally developed by Walt Conley and Ray Pittman for use at the Hanford Washington atomic facility. The process attempted to provide filtration in depth by having coarser media on the top of the filter with the finer materials underlying. Since the filter was cleansed of accumulated solids by back flushing from beneath the media, it was necessary that the coarser media be of a lesser specific gravity than the finer media. To accomplish this, the coarse media was composed of crushed anthracite coal and the finer media of silica sand.
The original filtration system proved very successful and was termed the Pit-Con process after its inventors. Later, Archie Rice, Ralph Roderick and others improved the Pit-Con process by adding very dense garnet sand to the filter bed and instituting numerous control changes. The result was Microfloc, an advanced technology that yielded a high quality treated water at high loading rates. Its ability to provide filtration throughout the entire depth of the filter rather than only at the surface (as with conventional filters) provided benefits that helped keep costs down for both water and wastewater clients.
Microfloc proved to be a catalyst that helped move CH2M from a regional consulting firm to a national operation when it was incorporated into the world's first major advanced wastewater treatment plant at Lake Tahoe, benefits that helped keep costs down for both water and wastewater clients.
The Microfloc process was instrumental in CH2M's obtaining work in the Eastern United States (Upper Occoquan Sewage Project) and opened prospects for international water and wastewater work.