Tor
FROM:

SUBJECT:

HOCKEY DEPARTMENT:

SOIL REMOVAL SL-LAN AND SETTLING BASINS SC ke:

FOR EXECUS ITCES FOR ONWARD TRANSMITTAL TO COUNCIL

oe oa my So edteeee - ae te eee 2 BE

This report is a summary of investigations carricd
out by Mr. Ashford and two majer reports prepared by
xr. J. tsun, PB. Eng., the professional cngineer who
joined & mid-November.

A. SETTLING BASINS

The major cause of silt transportation from the Gravel
Pit areas into the Coauitlam River is the fact that the Gravel
Pit operators construct settling basins as part of the water
courses flowing through their operations.

& settling basin should allow the majority or all of
the suspented sulids (mainly silts and clays) to settle cut
before the water, in which they are suspended, escapes into a
@rainage ditch or water course, The ideal conditicns for gcod
settienont are low velocities and a long time perioe between
entering the basin and leaving the basin. The longer the
periog of settlement allowed, the greater the percent of
Suspended sclids that will settle out

What has been happening to the settling basins that
ators have constructed in the water courses is that
WS and velacities have negated the effect of the

basins that have been obtained during low flows and

@ low veiccities. The high velocities give rise to
of the banks of the settling basins, with subsequent

the settled solids, which are then carried down-

It as the intention of this report to recommend that
ng basins be constructed in the working areas such that
rrablie flow in the creeks and other natural water courses

does not affect the operation of settling basins. This will
involve the construction of settiing basins adjacent to local
WOrkK axeas within the Gravel Pit operations. No water from a
gravel pit cperation or area should be allowed to enter the
niturs) water course, which flows into the Coquitlam River,
without it being filtered through a settling basin.

-2-

The construction and maintenance of the above-mentioned:
settlement facilities should conform to plans and specifications
prepared by a Professional Engineer registered wath the Asseciatioa
of Professional Engineers of Gritish Colusbia, and these plans
and specifications should be submitted as an integral part of the
Gravel Removal Peraxrt Application.

If the area of gravel pit operation is too small tc
accommodate all the settling basins on the west side of Pipeline
Road, then the processing of the silt and clay-laden waters would
have to be accomplished, at least partially, on the easterly side
of Pipeline Road. Tne necessity for this could easily be
established at the time of permit applications when the plans
of develepacnt are submitted.

Part of the gravel pit operation requires that gravel
be washed or cleancd to remove any silts or clays {such as that
used as concrete aggregate). In this type of self-contained
operation, the washing could be done by water recycled chrough
a settling basin having no outlets to ditches or creeks. This
method of washing ensures that no silt would reach natural
water courses.

BB. CONTROL OF CONTAMINATION OF CREEKS AND NATURAL WATER COURSES.

According to a portion cf Subsection (b) of Section 6
of By-Law 1489:

“all drainage facilities shall be kept free ef silt, clay,
Sand, rubble, debris, gravel and any other thing originating
from an excavation upon the lands and premises and causing
obstruction to such drainage.”

In other words, unless the silt, etc., causea obstruction
to the drainage, there is no violation of the By-Law.

According to Section 4 of By-Law 2041, Subsection (2) of
action 6 of By-Law 1489 has been revised to:

“no permit shall be issued 2f, in the opinion of the
Engineering Supervisor, the proposed soil removal vould
adversely affect any adjacent property, road, read allowcnce
or water course. “

This appears to be outlining a required condition before
isouance of a permit rather than a required condition during the
term of the permit.

It is suggested that Subsection (b} cf Section 6 of
By-Law 1489 be revised:

“All damage to municipal drainage facilities, roads or lanes
or other municipally owned preperty resulting froa the
excavation or the remaval of soil there-/rom shall be
repaired, All water entering a drainage facility

or natural watercourse shall be kept free of silt,

clay, sancé, rubble, debris, gravel and