Preliminary Design

Introducing the Preliminary Design
for the St. Mary DAF Plant

In 2013 the North Salt Spring 
Water District Board of Trustees commissioned Kerr Wood Leidal 
Consulting Engineers to prepare 
the preliminary design for a 
Dissolved Air Floatation (DAF) 
Water Treatment Plant at St. Mary 
Lake. The preliminary design is 
now complete.

As shown in the illustrations, 
the new treatment facility will 
consist of two structures: a 
primary building, and a 
“wet-well” housing the raw 
water pumps and intake pipes 
situated near the shoreline. 
The main floor of the primary 
building will house two (2) DAF 
Units and all the ancillary 
equipment such as pumps, 
pipes and electrical equipment. 
A small office, lab and bathroom will be located on the upper floor. The finished water will be stored in a clearwell under the building and pumped to the distribution system. Process waste will be stored in tanks for recycling or disposal.

A4_site_plan

The building will be constructed of poured-in-place concrete and have a footprint of approximately 2,500 square feet. The exterior will be clad with hardie-board siding and have windows so the building will somewhat resemble a residential home. Site landscaping will be suitable to re-establish any disrupted soil and trees to provide shade and generally beautify the facilities. The new facility will be located on the site of the current St. Mary Treatment Plant.

Download the article as a PDF

Note: Information on the Detailed Design will be made available soon.

Detail Design Costs

To view the Detail Design cost estimate (received February 23rd, 2015) for the new treatment plant please click here. Please keep in mind these are estimates.  We do not expect to exceed them, and in fact hope that they will be reduced even more during the bidding process.  It should be noted though that the falling dollar is effecting commodity prices. We continue to actively seek grant money and will be soliciting donations to reduce our borrowing costs.  Reserve funds will also be used to lower the final borrowing amount.

 

Some Key Reasons for the Design Choice and Location

  • Design suits operational needs and maximizes cost-efficiency of daily operations
  • Provides operational flexibility with the ability to pre-treat water
  • Site configuration maximizes use of gravity
  • Situation on site maximizes site access and egress
  • Underground storage maximizes security of treated water
  • NSSWD owns the property and is currently withdrawing water from this location
  • No major distribution system upgrades are required to bring the new plant online
  • Remote area with only a few homes in the vicinity
  • 3-phase hydroelectric power already exists at the lot line
  • Area on site available for standby power generation and fuel storage
  • Building construction has a long life cycle and minimizes sound transfer
  • Meets post-disaster construction requirements
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