Environmental Science & Engineering - www.esemag.com - June 2003
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Barrie’s first Horizontal Directional Drilling project completed in 2002
By R.J. Forward, City of Barrie and
Norman Sandberg,Ainley Group
In early 2002, the City of Barrie, Ontario, in co-operation
with the Ontario Ministry of the Environment
(MOE), determined that, under certain conditions, the
water output (106 Lps) from Heritage Well No. 14 had
insufficient chlorine contact time. To rectify the problem,
the City concluded that a new 1040-metre transmission
main to provide the required chlorine contact time was
required, along with a 622-metre distribution watermain,
complete with six new fire hydrants. The MOE required
that the new transmission main be in service by December
31, 2002.
The project site is in the heart of Barrie along the shore
of Kempenfelt Bay. The alignment was to be within the
abandoned railroad right-of-way in the vicinity of
Lakeshore Drive. An existing 1200 mm diameter sanitary
sewer, fibre-optic cables and various other utilities are
buried beneath Lakeshore Drive, parallel to the proposed
watermains. The project presented considerable challenges
since the alignment is immediately adjacent to a marina and
waterfront beach/park and also required three creek crossings.
Part of an old corduroy road was discovered beneath
the abandoned railroad right-of-way. This road may be a
remnant of an important link in the supply route from York
(now Toronto) to the former British naval base at
Penetanguishene. The naval base helped protect Canada
from invading American forces during the war of 1812.
A geotechnical investigation, undertaken by Peto-
MacCallum Limited, of Barrie, revealed a significantly
high water table along the proposed route. Groundwater or
wet cave was noted in the boreholes at depths of 0.3 to 2.4
metres. The soils comprise sand fill over discontinuous but
extensive layers of peat/organics over a major basal sand
component. Organic deposits of peat or marl were encountered
along the majority of the proposed alignment - ranging
in thickness from less than 1 metre to 4.5 metres and
extending down to depths of 4 to 10 metres.
The completed geotechnical report predicted long-term
settlement of up to 500 mm if conventional trenching and
backfill methods were used. To support the watermain and
provide the greatest assurance against settlement of the
pipe, the report suggested that a piled foundation system
and continuous grade beam would be necessary.
Following the geotechnical investigation, the Ainley
Group was retained to analyze the cost-effectiveness of
conventional design, the requirements for dewatering, optimum
trench support and watermain structural support (pile
and grade beam). Consideration was also to be given to a
submarine crossing beneath Kempenfelt Bay - but only on
a conceptual basis.
Approximately 70% of the transmission main and
almost 100% of the distribution main and fire hydrant locations
lay within an area of deep organic deposits. The
Ainley Group determined that these site conditions indicated
horizontal directional drilling (HDD) with HPDE pipe
was a construction method worth considering; however,
this method was unfamiliar to the City of Barrie, and
HDPE pipe was not on its approved material list.
Nevertheless, the draft pre-design report addressed four
construction alternatives.
Abridged
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