Module 6 — Shock Chlorination
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Modified Procedure for Large Diameter Wells
Due to the large volume of water in many bored wells the above procedure can be
impractical. A more practical way to shock chlorinate a bored well is to mix the recommended
amount of chlorine right in the well. An extra volume of chlorinated water is used to force
some of the chlorine solution into the formation around the well. Follow these steps to shock
chlorinate a large diameter bored well.
Pump 200 gal. (1000 L) of water into a clean storage tank at the well head.
Mix 4.0 L of 5 1/4% domestic chlorine bleach that does not have additives or perfumes
(
or 1.5 L of 12% bleach or 0.26 kg of 70% calcium hypochlorite) into the 200 gal. of
stored water. This mixture will be used later in Step 5.
Using Table 1 calculate the amount of chlorine you require per foot of water in the
casing and add directly into the well. (Note that the 70% hypochlorite powder should
be completely dissolved in a small container of water to form a solution before placing
in the well.)
Circulate the chlorinated water in the well by hooking a cleangarden hose up to an
outside faucet and placing the other end back down the well. This circulates the
chlorinated water through the pressure system and back down the well. Continue for
at least 15 minutes.
Siphon or drain the 200 gal. bleach and water solution prepared in Steps 1 and 2
slowly into the well.
Complete the procedure as described in Steps 5 to 9 for drilled wells.
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Worksheet
Use the "Calculating Water and Chlorine
Requirements for Shock Chlorination"
worksheet to determine how much water
and chlorine you need to shock chlorinate
your well. A sample worksheet is included
at the back of this module. Working copies
are included in the pocket on the back
cover. Store the completed worksheet in
the back pocket.
Don't mix acids with chlorine.
This is dangerous.