Marathon Norco Aerospace located in Waco, Texas is one of the few manufacturers of rechargeable, nickel cadmium batteries for the aerospace industry. One of the production problems associated with the manufacture of rechargeable, nickel cadmium batteries is the use of a number of heavy metals. Two of the metals which can be problematic when it comes to waste disposal are cadmium and chromium.
The amount of heavy metal waste generated at the Waco facility categorized the plant as a "significant hazardous waste generator," which created costly off-site hazardous waste disposal and extensive record keeping and documentation. Since 1972, the plant has used a diatomaceous filter system to reduce the volume and concentrate heavy metals in the waste. The plant's hazardous waste production required transport from the plant of over 100,000 pounds per year.