Key Manhole Program

In the King County sewerage system, all wastewater from each sector of land flows through a central point known as a key manhole.

Industrial Waste Program specialists sample discharges from selected key manholes. Then they prepare data to track what is normal and to spot changes or anomalies.

Any illegal discharge detected usually can be traced to a specific industry in the sector of land that feeds the key manhole because the discharge will have characteristics typical of that industry. This program means that Industrial Waste often can stop harmful waste from adversely affecting sewage treatment plants and surface-water quality.

Below is a photo of a key manhole, into which a sampling device has been placed. The second photograph shows the sampler taken apart and its control mechanism.