STAFF REPORT
September 3, 1999
To: North York Community Council
From: Wayne Green, Director, Quality Control & System Planning
Subject: Water Distribution System Analysis: Area within Ward 8 Bounded by Highway 401 to the south, Steeles Avenue
to the north, Keele Street to the west, and Bathurst Street to the east
Purpose:
To respond to a resolution embodied in Report No. 15 of the North York Community Council, as adopted by Toronto City
Council at its meeting of December 17 and 18, 1998 requesting a review of water pressure in the area bounded by Highway
401 on the south, Steeles Avenue on the north, Keele Street on the west and Bathurst Street on the east.
Financial Implications and Impact Statement:
Funding to address fire flow protection deficiencies identified in the analysis, in the amount of $3,320,000.00, will be
requested in the 2000 Water and Wastewater Services Capital Works Program.
Recommendations:
That this report be received for information.
Background:
In June, 1998, Environmental Hydraulics Group, a consultant working for Canada Lands Corp., submitted a hydraulic
analysis report to support the redevelopment of the Downsview Base Lands. These lands are substantially higher in
elevation that the surrounding area in Pressure Zone 5 and would not receive adequate pressure from a conventional
connection to the adjacent watermain network.
The consultant's recommended alternative was to extend Pressure Zone 6 approximately two kilometres to the south
(Figure 7). Pressure Zone 6 can supply water at a significantly higher pressure to most of the proposed development. This
alternative would also result in a substantial increase in pressure to the area immediately north of the Base Lands, which
currently has substandard static pressure.
However, Pressure Zone 6 cannot provide sufficiency fire flow capacity to the Base Lands because of the friction losses
over the extra distance from the Keele Pumping Station. Additional flow would have to be provided from Pressure Zone 5
using one-way check valves that only open under fire flow conditions. In order to more fully evaluate the impact of the
consultant's proposal on the existing water distribution system, City staff began assembling a network analysis computer
model for this area.
In December, 1998, City Council adopted the recommendation by North York Community Council that the City
commission a review of water pressure in the area bounded by Highway 401 on the south, Steeles Avenue on the north,
Keele Street on the west and Bathurst Street on the east. Most of this study area falls within Pressure Zone 5 West and
Pressure Zone 6, shown in Figure 1.
A study was subsequently undertaken to address the following objectives:
- To evaluate a proposal submitted by Canada Lands for servicing the Downsview Base Lands;
- To address the concerns raised by North York Community Council regarding water pressure deficiencies in the area
bounded by Highway 401 to the south, Steeles Avenue to the north, Keele Street to the west and Bathurst Street to the east;
and
- To evaluate the general hydraulic capacity of the system within the western part of Pressure Zone 5.
Comments:
Residential Pressure Complaints
Internal flow tests (at the water meter inside the house) have indicated that a substantial number (greater than 5%) of the
homes in the area bounded by Sheppard Ave., Dufferin St., Finch Ave. and Bathurst St. have inadequate internal flow
capacity (less than 18 litres/minute) as defined by the City's new Residential Service Connection Repair Program. The
average recorded internal flow capacity for homes with inadequate capacity is only 11 litres/minute. The public road
allowance portion of the connections in these locations have been, or are in the process of being, replaced as part of the
repair program.
In carrying hydrant flow tests for model calibration, a particularly dense grid of tests were carried out in the above area.
These tests indicated that there is adequate flow capacity and pressure in the general watermain network in this area (a
summary of the flow test reports is included in the Technical Report). The inadequate internal flow capacity is the result of
older ½" diameter water service connections that have accumulated internal deposits that severely restrict their flow
capacity.
Fire Flow Capacity
The hydrant flow tests did indicate that there are a number of other locations where fire flow capacity is inadequate or just
barely adequate. These locations were generally in small sub-areas, where flow is only supplied in one direction from the
major network, and where extensive rehabilitation has not been carried out. The most severely deficiency was found at the
end of Timberlane Drive, which is a particularly long cul-de-sac.
Remedial Alternatives for Fire Flow Capacity Improvement
The assembled network analysis computer model was calibrated using field measured test data and then used to evaluate
the capacity of the network and to test remedial works alternatives. The flow tests were used to calibrate the computer
model, and the model was used to evaluate the existing capacity of various parts of the network and to test remedial works
alternatives. A comprehensive review of watermain break history data was also undertaken to determine whether the
remedial works should consist of replacements or cleaning and lining. A summary of recommended works is shown in
Figure 2 to 6 and provided in the following:
| RECOMMENDED WORKS |
ESTIMATED COST |
| Watermain replacement the watermain on Timberland Dr.
(Fig. 2) |
$300,000 |
| Watermain replacement works in the Armour Blvd. Area
(Fig. 2) |
$625,000 |
| Watermain cleaning and lining works in the Armour Blvd.
Area (Fig. 2) |
$575,000 |
| Watermain replacement works on Maple Leaf Dr. (Fig. 3) |
$450,000 |
| Watermain replacement works in the Exbury Area (Fig. 4) |
$245,000 |
| Watermain cleaning and lining works in the Exbury Area
(Fig. 4) |
$205,000 |
| Watermain Replacement works in the Firgrove Cr. Area
(Fig. 5) |
$350,000 |
| Watermain cleaning and lining works in the Strathallan
Wood Area (Fig. 6) |
$570,000 |
| TOTAL: |
$3,320,000 |
Review of Base Lands Servicing Proposal
The network model was also applied to assess the consultant's recommended servicing alternative for the Base Lands (Fig.
7). The analysis indicates that the consultant's alternative will generally function as predicted. The additional draw from
Zone 5 under fire flow conditions will not result in an unacceptable drop in pressure in the neighbouring area. However,
the modelling indicated that the dead-ends created through the proposed closure of gate valves on Ashwarren Dr. and
Steeprock Dr. will result in some local flow deficiencies. Instead of the closed gate valves, there is a need for two
additional check valves in these locations.
Improving Residential Flow Capacity
Some consideration was given to evaluating a further modification of the pressure zone boundaries to increase static
pressures in the complaint area mentioned above. However, as previously discussed, the average flow capacity in
substantial locations was found to be only 11 litres/minute. It is estimated that the static pressure would have to be raised to
~ 790 kpa in order to force an adequate amount of flow (18 litres/minute) through these connections. This level of pressure
is not practical and could not be supplied even if the complaint area was supplied through Pressure Zone 6.
The only practical alternative for improving residential flow capacity is to replace the service connections in those
locations with substandard flow capacity. In June, 1999 Council adopted a Harmonized Residential Water Service
Connection Repair Program. As part of this Program, the City has committed to replacing the portion of service
connections within the road allowance in locations where the flow capacity measured at the house meter is less than 18
litres/minute (which is an enhancement over the former City of North York criteria of 15 litres/minute). While there is
sufficient capacity in the local watermain network to provide more than 18 litres/minute to the homes, the full potential of
the improvement is realized if the homeowner also arranges for the replacement of the portion of the service connection on
private property.
Conclusions:
The remedial works recommended as a result of this study will improve the water distribution system's ability to provide
adequate flow capacity under fire conditions. Funding to address fire flow prevention deficiencies identified in the analysis,
in the amount of $3,320,000, will be requested in the 2000 Water and Wastewater Services Capital Works Program.
Resident complaints regarding inadequate internal flow pressure can best be addressed through the City's new Harmonized
Residential Water Service Connection Repair Program. It is estimated that $12 million will be budgeted for this program
City-wide in the 2000 Water and Wastewater Services Capital Budget.
Contact:
Eric Arm, P. Eng.
Team Lead,
Water Distribution Asset Management & Modelling
Telephone (416) 395-6234
Wayne Green, P. Eng.
Director of Quality Control and System Planning
Water & Wastewater Services
Works & Emergency Services
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