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Module 6 — Shock Chlorination
Shock Chlorination Procedure for Drilled Wells
A modified procedure is also provided for large diameter wells.
Caution: If your well is low yielding or tends to pump any silt or sand, you must be
very careful using the following procedure because over-pumping may damage the well.
When pumping out the chlorinated solution, monitor the water discharge for sediment.
Store sufficient water to meet farm and family needs for 8 to 48 hours.
Pump the recommended amount of water (see Table 1, Amount of Chlorine Required
to Obtain a Chlorine Concentration of 200 PPM) into clean storage. A clean tank,
used only for storing potable or chlorinated water should be used. The recommended
amount of water to use is twice the volume of water present in the well casing*. To
measure how much water is in the casing, subtract the non-pumping water level from
the total depth of the well. See the example below.
Imperial Example
The drilling record indicates the casing is 200 ft. in length and the non-pumping
("
static") water level is 100 ft. The length of casing that is holding water in it is 100 ft.
(200-100).
If your casing is 6 in. in diameter you need to pump 2.4 gal. of water for every
foot of water in the casing, into your storage container. Since you have 100 ft. of water
in the casing, you will pump 2.4 gal./ft. x 100 ft. = 240 gal. of water into storage.
Using Table 1, calculate how much water you need to pump into clean storage.
Casing diameter_________ needs_________gal./ft. x __________ ft. = ____­______ gal.
Step 1
Step 2
*
Large cisterns should be bypassed and
treated separately. If the water must
travel through a long or large diameter
pipeline, or large pressure tanks, an
extra volume of chlorinated solution
should be used. Consult with a licensed
water well drilling contractor or a
water specialist.