Chlorine Monitoring and Dechlorination Techniques Handbook

Chlorine Monitoring and Dechlorinating Techniques Handbook
The approach used by GVWD staff for dechlorination in an emergency situation is to use the
solid form of anhydrous sodium thiosulphate. This agent is put into fibre mesh bags, which
are then placed in the flow path of the released water. Therefore, a number of bags should
be readily available. Rope is included in the equipment list as often the bags need to be tied
in place. Personal safety equipment is also required.
It is important to have Material Safety Data Sheets (MSDS) on the site for both the
dechlorinating agent and for the chlorine testing kit. If there is contact with either of these
agents, the MSDS provides information pertaining to treatment, if required. The MSDS will
also indicate the exact personal protection equipment (PPE) that should be worn by workers
who are in contact with the chemicals.
Planned Situation
In a planned release, the equipment and supplies will be different from an emergency
response as the liquid form of the dechlorinating agent can be used.
Sufficient dechlorinating agent should be delivered to the site prior to the beginning of any
planned operation. Excess dechlorinating agent should be available at all times. Since it may
not be available from the suppliers on short notice.
Table 3-2 indicates typical supplies that should be kept on site for a planned response.
3.2.2 Step 2 - Notify Authorities and Record Activities
In an emergency situation, it is important to notify the correct authorities immediately upon
learning of an unplanned release of chlorinated water. Notify the authorities with jurisdiction
in the vicinity of the release. For instance, if a City of Vancouver water main broke in
Vancouver, the City would have jurisdiction and has a designated reporting number for water
main breaks. Alternatively, if a water main operated by the GVWD broke, the GVWD should
be contacted. Exact procedures for contacting authorities should be pre-planned by all
municipalities, and the GVWD. An Emergency Call Report Form, as outlined in the Generic
Environmental Emergency Response Plan for Chlorinated Water (GVRD 1997), should be
filled out to record all persons and agencies notified.
In the event of a large spill, the Provincial Emergency Program (PEP) should be contacted.
Although, they will likely refer the call to the Department of Fisheries and Oceans, this
agency should also be contacted directly.
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