Wellhead Protection, Source Management and Monitoring for a Class T System
The well is the treatment plant
On a system whose only treatment is disinfection, the protective barrier is the well structure
and the aquifer above it. Each construction element has a specific job:
- Casing isolates the borehole so water enters only from the intended producing zone.
- Annular seal (grout) fills the space between casing and borehole wall. Without it, surface
water and shallow contaminated water run straight down the outside of the casing to the
producing zone, bypassing every inch of natural filtration. A defective annular seal is one of
the most common causes of persistent coliform positives in an otherwise sound well.
- Screen or open interval admits water while excluding formation material.
- Sanitary well cap seals the casing top against water, insects, ro