Chlorine Monitoring and Dechlorination Techniques Handbook

Construct the injection point
Chlorine Monitoring and Dechlorinating Techniques Handbook
The injection point should be constructed to intercept the inlet pipe to the pond. This allows
mixing prior to the water entering the pond.
A chemical metering pump 6 can be fitted to the top of the injection point to allow the
operator to control the flow rate of dechlorinating chemicals into the injection point. Some
specifications for pumps are attached in Appendix C. To calculate the dosing rate of
dechlorinating agent in solution, refer to Section 3.0. Routine monitoring of the water for
chlorine residuals should occur to ensure proper dechlorination.
In the case of a pond, the structure is likely to be permanent. In this case it is recommended
that a shed be constructed to house the dechlorinating chemicals, and the chemical metering
pump. Power would need to be provided to the site. The shed should be kept locked to
prevent tampering. The shed will also ensure that the chemical metering pump is protected
from the elements.
It is also recommended that some rip-rap be placed at the base of where the inlet pipe will
discharge water into the pond. This will prevent erosion of sediments on the base of the pond
and discourage sediments from being churned up by the energy of the incoming water.
5.2 In-line Injection
The in-line injection method involves mechanically injecting dechlorinating agent into some
type of piping system. As the type of systems that may require this approach varies greatly,
only general concepts can be provided in this handbook.
Injection Point
The injection point should be constructed to intercept the existing piping a minimum of 10
m from the point of discharge to a receiving water body. The system must ensure sufficient
mixing of the chlorinated water with the dechlorinating agent while the water is still inside
the pipe. The method of injection should also ensure throughout mixing of the water with the
dechlorinating agent.
Flow Measurement
In a pipe with relatively constant flow, a metering system can be set at one specific addition
rate. No monitoring of the flow in the pipe would be required. However, if large variations
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Chemical metering pumps are available from local suppliers.
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