~d.

Options 3, 4, 5, and 6 assume rechlorination is used and provide choices of both Coquitlam and Seymour as
future sources. Options 3 and 4 are forward looking and are based on the premise that THMs are presently and
will remain significant issue. These options aiso include filtration immediately to enable the GVRD to meet
present and future THMs standards, which is consistent with the Medical Health Officers! concems.

Options 5 and 6 are based on the premise that THMs and other disinfection by-products are not major concerns
and that the permanent level for THMs will remain at the interim level. This is just the opposite of Options 3
and 4, |

4
A summary comparing the costs and effectiveness of each Options are illustrated in Tables 2 and 3 respectively.
COMMENTS:

The GVWD Board of Directors have the task in deciding whether the GVRD should use rechlorination (higher
chlorine levels) or chloramination to provide a secondary disinfectant residual throughout the water system. The
decision will have significant environmental and economical impact on GVRD municipalities.

If health issues, palatability to consumers, and overall costs of implementation are the major issues, the Board —
should choose chloramination. However, chloramine has a higher risk of impact to the aquatic environment.

[f enviromental perspectives are the major issues, the Board should choose rechlorination (higher chlorine
levels) since the frequency and magnitude of its impacts will be less than those from use of chloramine.

If health issue, palatability to consumers and environmental perspectives are the major issues, the Board should
choose filtration and ozone with biological filtration to reduce or minimize the amount of secondary disinfectant
required in the drinking water. This treatment will provide the highest water quality. However, the costs of
implementation will be significantly higher than chloramination or rechlorination. |

Port Coquitlam is located in an environmentally sensitive area with numerous fish habitat streams and creeks
(See Plan 1), The impact to the environment (i.e. fish and fish food organics kill) will be significant if
chloraminated water flows into a stream or a creek in the event of a broken watermain. From historical records,
there have been approximately 62 incidents of watermain break between 1991 and 1993 in Port Coquitlam.
Under the Federal Fisheries Act, there may be significant legal ramifications if chloraminated water is released
into a fish habitat stream or creek. |

_ It is recommended that Committee reject outright the use of chloramine as a secondary disinfectant residual
throughout the water system.

it is recommended that Committee consider supporting Option 3b to provide secondary disinfectant residual
throughout the water system: _

Filter all sources,
New dam at Seymour Falls. .
Ozone (with biological filtration) to replace chlorine as a primary disinfectant.

Minimal number of rechlorination stations (20 to 30).
Ultimately fully utilize Coquitlam watershed.

Cont'd. .../5