EP 1110-1-27
27 Jan 00
Problems to Watch For
Well siltation (fine material enters the well and settles to the bottom, ultimately occluding the screen)
Solution: periodic sounding of the well and bailing the sediment when it reaches a certain height above the
bottom cap.
Well encrustation or fouling (common problem, scale or biological growth forms on well screen, reducing
open area and increasing water entrance velocities, typically manifested by reduced specific capacity of the
well). Solution: periodic rehabilitation when the specific capacity decreases to a predetermined level
according to a protocol appropriate for the cause of the reduced capacity.
Physical damage to the well due to frost, vehicles, vandalism (can limit or prevent use of the well,
compromise integrity of the well and allow contaminated surface water to migrate to the subsurface).
Solution: inspection and repair. Severe damage can require well replacement. Damaged well must be
decommissioned in accordance with state requirements.
Excess sand/turbidity production even after extensive redevelopment (due to corrosion, inadequate design
of filter pack and/or screen). Solution: well replacement. Other alternatives (e.g., selective pressure
grouting of an affected zone or blank casing / small-slot screen inserts) could be considered for very
expensive/deep wells but may not result in adequate well performance.
Process Monitoring
Not Applicable
Alternatives for Possible Cost Savings
Extraction Wells:
Consider the following alternative
Extraction trenches (have increased intake area, lower entrance velocities.
Treatment walls or wells (see Ground Water Extraction Technology checklist)
Monitoring Wells
Buried Sensors
SeaMIST
Direct Push Probes
Sheet 2 of 2
Plate D-6
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