Washington Regulatory Flashcards
Resource protection wells (standard vs DP: minimum annulus size relative to casing
Annulus must be 4 inches greater diameter than well casing/screen
DP: 1 inch greater
Resource protection wells (standard vs DP): sand pack height relative to screen
Sand pack must be 1-5 feet above screen
DP: Sand pack must be 1-3 feet above screen and 0-1feet from bottom of screen
RP well decommissioning - with and without well log information
If you have well log:
Wells greater than or equal to 1 inch diameter: fill casing with bentonite chips, grout, cement, surface seal.
Wells less than 1 inch (DP): pressure fill with grout and seal at surface
If you don’t have the well log:
Perforate casing and pressure fill with grout or pull casing and seal boring
Water wells - minimum length and diameter of surface seal
18 feet below ground surface and 4 inches greater than maximum casing diameter. Seal must extend to and through the confining layer
Well sealants include
Bentonite (slurry or dry - slurry must have 20% by weight bentonite solids content)
Neat cement (6 lb water per 94 lb cement solids - portland or high alumina)
Cement grout (neat cement, with up to 5% bentonite by weight)
Concrete (portland cement with aggregate)
Sealing of wells penetrating confined aquifers
Must be sealed from ground surface to bottom of upper aquitard, or ground surface to minimum 18 feet
Decommissioning of water wells
Either perforate the casing to within 5 feet of the surface, then pressure seal,
or
withdraw casing and fill with sealant.
Flowing artesian wells must be filled with grout from bottom to surface using tremie