Sooke Flowline

During the year of 1912, the city expropriated 40 property owners on Sooke Lake and on the proposed flowline right-of-way (ROW) at great cost. The city hired the Pacific Lock Joint Pipe Company to cast the pipe segments and using their patented design, constructed the pipeline. In between 1911–1915, this major engineering project employed over 400 workers and housed their families in rural Sooke. The pipe is almost completely at a constant elevation. Although figures vary, the slope from Sooke Lake to Humpback is between 0.0947% and 0.119% when the inverted siphons are excluded.

At the factory located at Coopers Cove, at the site of today's Stickleback Bar and Grill, round concrete segments, 36,000 in all, were mass-produced. The engineering firm, Sanderson and Porter, specified 40-inch pipe, but the company already had 42-inch molds made up so they decided to use them instead. The factory was very efficient and used steam to accelerate the curing of the concrete segments. In one 8-hour shift, 150-160 segments were produced. The segments were winched up the hill 450 feet (137 m) above the construction site.[3] Three small locomotives were used to bring segments to both ends via a temporary 2 ft (610 mm) gauge railway and the pipe was constructed from the ends to the midpoint.[4] At the ends, tripod derricks would unload the segments and placed them on the crushed railbed while the tracks were removed. All trees on the 100 ft (30.5 m) right of way were cleared so that they could not fall and crush the pipe.

Panorama of the Sooke Flowline looking east above the Sooke River near today's Sooke Potholes Regional Park.

During the flowline's operation, caretakers lived along the route in small cabins; many of them are still there today. They rode recumbent tricycles on the pipe with tilted rear wheels to stay on top. During their routes they were on the lookout for cracks in the pipe, leaky joints and trespassers.

Every 600 metres (660 yards) or so there are access hatches. These were meant for periodic maintenance from the inside by workers. A man would lie prone on a cart and scrape moss off the inside of the pipe and clear sediments, rocks and dead fish which inevitably backed up in places. Placed on top of these hatches were wire mesh domes, which reduced pressure build up and helped aerate the water.

Evidence of leaking on the pipe and broken iron bands demonstrate why decommissioning was necessary.

Another example demonstrating the vulnerability of the pipe.

The flowline was never great efficiency wise. When the taps were opened in 1915, the water which came through was high quality, but they soon discovered that they were experiencing a 50-75% water loss throughout its length, depending on the season and temperature. During summer however, the leaking was slightly reduced. This needed to be remedied by placing strips of material across the joints and fastening them with iron bands. A further challenge experienced was that the winter of 1915-16 was one of the worst in history. Parts of the newly constructed pipe got taken out by landslides and repair was difficult since the construction railway no longer existed. When the city began to outgrow the demand, the pipe section from Sooke to the Humpback Reservoir was decommissioned in 1970. The pipe had begun to show its age with many leaks and damage from falling trees and rocks. This was then replaced with the 8.8 km (5.5 mi) Kapoor Tunnel bored through solid rock to the Japan Gulch Disinfection Plant near Goldstream Provincial Park.

The portion of the old pipe from Sooke Lake to Sooke remained in service after the Humpback Reservoir section was decommissioned. This portion was routinely patrolled to make sure marijuana grow ops weren't tapping into the pipe and to do periodic patching up as best as possible, but it still had many leaks. Damage had also resulted from falling rocks and trees and there were concerns whether it could survive a major earthquake. The pipe by nature is fireproof. Finally in late 2009 it was replaced with a PVC pipe buried under the Galloping Goose Regional Trail. It connects to the Sooke River Road Disinfection Facility which went online in 2009. The facility incorporates ultraviolet disinfection (UV), and is followed by the addition of chlorine and ammonia.[5]

The water department of the Capital Regional District still owns pipe and the approximately 100 ft (30.5 m) wide corridor which includes large trees, cliffs, and mossy bluffs.

There are 54 trestles along the 44 km (27 mi) length of various sizes spanning ravines. During construction, temporary timber trestles were built alongside the proposed trestles to avoid construction delays and speed up construction of the permanent concrete trestles.

The largest part of the pipeline consists of reinforced concrete segments which are four by four feet (1.22 by 1.22 m).

Six concrete trestles are made out of wood staves preserved with creosote and bound with iron bands. These were built to reduce the length around the longest of ravines. The wooden trestles actually dip down one side of the ravine and go up the other relying on the downward pressure to push the water back up. These "dipping" trestles, known as "inverted siphons", were initially constructed of concrete as well but the material is very weak in tension and resulted in cracked segments due to the pressure of 39.017 psi (269.01 kPa) (abs).

There is also one metal trestle over Ayum Creek near Sooke.

• Lubbe Powerhouse

Wikimedia Commons has media related to Sooke Flowline.

• The Sooke Parks Master Plan
• An article about the Sooke Lake water supply by Victoria's Ross Crockford
• A PowerPoint about the Sooke Flowline's historical significance
• Images of the line East and West of Impala Road
• Hiking information about the Sooke Flowline