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APPENDIX ‘A’

CITY OF PORT COQUITLAM
PRE-DESIGN REPORT
LAURIER FLOOD BOX RIVER CHANNEL ee

4

4,
p

SUMMARY AND RECGMMENDATIONS
Summary

1, The Northeast Sector of the City of Port Coquitlam is drained by a flood box an
the east end of Laurier Avenue through the Pitt River dyke and by a pump
station and flood box on the east end of Dominion Avenue. (see Fi 4, @- 1)

Presently flooding problems are concentrated in the area immediatc., upstream
of the Laurier Avenue flood box. Flooding occurs during high river stages when.
flapgates are shut and insufficient storage volumes are available in existing
lowland ditches. Thie condition typically occurs during freshet when for
example 1:2 year river stages preclude the possibility of gravity discharge via the
Laurier floodbox for at least one month or during high tides in the winter in

conjunction with peak upland drainage flows,

The existing Northeast sector drainage network is linked by a series of

interconnecting ditches.

The future development area in the Northeast Sector is currently in the 2 m to
4 m Geodetic elevation range and is protected from flooding from the 200 year
Pitt River water level by dykes with a top elevation of 5.0 m Geodetic. This
land will be fillad above the 5.0 m Geodetic level as development proceeds. The
Master Drainage Plan for land raised to this level is to provide large conduits
for gravity discharge via two flood box outlets - one at the foot of Laurier
Avenue, the other at the foot of Dominion Ave. No pumping is to be provided

in the future.

The Master Drainage Plan selected involves staged implementation as

development proceeds. The western portion of the Dominion area is proposed

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