Stormwater management - Southwest Washington

Drywell lid

Above: typical lid of a drywell facility. Below: a well maintained interior, note the holes that allow the water to soak into the ground.

Interior of drywell




A drywell is an open-bottomed manhole used to infiltrate stormwater into the ground through holes in the walls. Drywells rely on the stormwater soaking into the surrounding soil. They trap sediment and oily pollutants in runoff, and they can fill with oily sediment in areas that lack treatment facilities. Because drywells can be clogged and tend to concentrate pollutants in one place, pollution and sediment control practices should be used to protect them. 

Signs that maintenance is needed and a checklist for maintaining the facility including how to fix problems.

Additional elements to drywells

Field inletField inlet
A field inlet is a concrete structure that collects stormwater and routes it through underground pipes. Fitted with a slanted, slotted grate, it often traps sediment and debris. Regular maintenance is important. Keep the opening clear of obstructions. A field inlet is usually cleaned by a truck with a vacuum hose but sometimes can be cleaned with hand tools.