by Bruce Cherney (part 3 of 3)
The Romans didn’t invent the aqueduct — it’s an honour which falls to the ancient Assyrians, whose engineers were well aware that water flows downhill. King Sennacherib (721-705 BC) ordered the world’s first recorded aqueduct and canal system to be built to supply his capital at Ninevah with water from mountain streams 16 kilometres away.
Despite the Assyrians inventing the aqueduct, the Roman Empire is now more closely associated with the gravity system used to carry water to towns and cities. Today, the remains of the towering multi-tiered arches used to span valleys and hold aqueducts aloft are viewed as marvels of Roman engineering.
In ancient Rome, 11 separate aqueducts supplied water to catch-basins where sediment was allowed to settle before the water was moved on via terracotta and lead pipes and canals to enormous cisterns located on high ground around the city. At its height, Rome claimed a population of one million, and the strength of the city’s aqueduct system was that it supplied nearly one cubic metre of water per person, an amount that would be the envy of residents of many modern cities.
The designers of the Shoal Lake aqueduct employed construction techniques that in many ways mirrored the aqueducts built by Roman engineers.
The engineers involved in the construction of the Shoal Lake aqueduct from start to finish were James H. Fuertes of New York and Greater Winnipeg Water District chief engineer W.G. Chace, but the actual horse-shaped design of the aqueduct resulted from the 1913 report by engineers Fuertes, Dr. Rudolph Hering of New York and Frederick P. Stearns of Boston. The three engineers had attached blueprints of the aqueduct design to their report.
“This was not only one of the major engineering projects of its era,” said Rod McRae, the city’s commissioner of works and operations in a 75th anniversary article on the aqueduct published in the WREN on April 15, 1994. “It was, and still is, one of the longest gravity-fed covered aqueducts built in the world since the early Romans pioneered aqueduct construction more than 2,000 years ago.”
To plot the path and slope of the 156-kilometre-long Shoal Lake aqueduct, five survey crews completed 580 kilometres of transit lines, 2,100 kilometres of levels, 152 kilometres of precise levels and 3,510 metres of lake soundings to find an alignment that as nearly as possible followed the principle of a westward slope from the intake to Winnipeg, according to the article, Winnipeg’s Aqueduct in Western Canada Water magazine, fall 2008. “With downtown Winnipeg in sight, the final alignment was only about 13 kilometres longer than would be measured as the crow flies from the intake.”
The available grade for the gravity system from Shoal Lake to Winnipeg was only 90 metres, and the survey work resulted in the slope of the aqueduct being 0.57 metres every 1,000 metres.
Actual construction on the aqueduct began after the opening of tenders on September 19, 1914. Three major Winnipeg-based companies — Tremblay McDiarmid Company, Thos. Kelly & Sons Ltd., and the Winnipeg Aqueduct Construction Company — were awarded the contracts for the aqueduct. The first phase involved the diversion of the Falcon River, which had previously flowed into Shoal Lake at Indian Bay. The diversion was a key to the project as it allowed the development of the Indian Bay source without the need for treatment based on aesthetics (colour), according to Ron Sorokowski and Duane Griffin, from the city’s water and waste department, and Chris Macey and Ken Skaftfeld, of UMA Engineering Ltd., the authors of the 2008 article Winnipeg’s Aqueduct.
On July 5, 1915, the Free Press reported that prior to the diversion, the Falcon River discharged dirty-looking water into a corner of the bay, as a result of swamp water draining into the river.
Before construction on a gate house and pumping station at Indian Bay commenced, large boulders at the intake site were removed by blasting and a dike was built near the entrance of the bay to divert the Falcon River.
Fuertes and Chace were on-hand when the first earth for the Falcon diversion into Snowshoe Bay was lifted by a steam shovel on June 17, 1914.
The Winnipeg Free Press on March 13, 1918, reported building the 7,000-foot-long (2,133.6-metre) dike required “about 230,000 yards of material, all of which was obtained from a borrow pit and quarry located at the north end of the dyke (sic).
“A large number of drainage and off-take ditches were necessary in order to drain the country properly before actual construction of the aqueduct was commenced” on May 15, 1915.
Although the route for the aqueduct was over swamp, muskeg, sand and rock, overall construction was alleviated by the fact that it was downhill for most of its length with the exception of 14 kilometres from Indian Bay. A deep cut several metres down in the rough land was made during this initial phase of the aqueduct construction.
The aqueduct was built under the Whitemouth and Falcon rivers using inverted siphons. In total, four rivers were burrowed under at six locations by using inverted siphons, a process used in Roman aqueduct construction.
The trench running the aqueduct’s length was rough-cut using steam shovels, dredges and dragline scrapers with workers trimming away the remaining 150 millimetres by hand. By the end of the project, 1.65 million cubic metres of earth had been excavated.
Less than a year into the project, the First World War intervened. The March 13, 1918, Free Press, when reporting on the history of the aqueduct, said the war had the “effect of making it much more difficult to secure money and also causing a scarcity of labor.”
Despite the pressures of the war effort depleting the available labour pool, over 2,500 workers would be involved at the peak of the project’s construction phase.
The Free Press said over the course of the first year, 21.4 kilometes (13.3 miles) of the aqueduct were built, or 14.6 per cent. During the 1916 season, 37 kilometres (23 miles) were built, so that the project was by then 41.6 per cent complete.
The method used to build the aqueduct was cut-and-cover. A one-metre trench was dug and a horseshoe-shaped conduit, averaging about 2.7 metres in height, was poured between steel forms. When the concrete cured, the forms were stripped and the pipe was covered by earth, which was necessary to prevent the water from freezing during Manitoba’s cold winters.
Every 1,524 metres, manholes were installed to allow for maintenance inspections. Surprisingly, early inspections of the aqueduct’s interior involved lowering the water level and men then boating through the sections.
“The invert slabs were poured in alternating 4.5-metre-long sections and screeded to a smooth surface,” said the authors of Winnipeg’s Aqueduct. “Once these sections were cured, closure sections were poured. Following immediately after the completion of the invert slabs, the arch was built in 13.7-metre-long sections, also in an alternating pattern, using an inner and outer slip form. The forms were advanced along sets of rails on the middle and outside edge of the completed invert. Several reinforced crossings were provided within the upper reaches in anticipation of future road crossings ...
“The specifications also required that between the walls of the trench and the aqueduct select earth backfill would be tamped carefully in 150 millimetre lifts to a depth of 1.2 metres. As the designers explained, this precaution was taken in conjunction with a moderately light design of arch.”
However, the arch was “quite safe against the pressures of earth backfill even without packed earth at the haunches.”
A steam shovel was then used to place the remainder of the backfill over “the aqueduct to a depth of 1.2 metres in the case of solid material or 1.5 metres in the case of peaty material.”
The GWWD supplied all the cement required for the aqueduct, but contractors were charged for any wasted cement.
“All aggregate (mixed with the cement to make concrete) is supplied by the district (GWWD) and delivered to the camp sites of the contractors,” reported the Free Press. “This is obtained from gravel pits along the route of the (Greater Winnipeg) Water District railway. Machinery is maintained at the pits to crush and mix the pit run gravel, so that the aggregate is graded in such a manner to make the densest and most watertight concrete.”
By controlling the cement and aggregate, the GWWD was ensuring the concrete used in the aqueduct was of the highest quality.
As was the case in aqueducts serving ancient Rome, water from the Shoal Lake aqueduct was channeled to a massive reservoir. At Deacon, 13 kilometres east of Winnipeg, water from the cistern was distributed via pipelines to the city and the several municipalities making up the GWWD. Over the years, the main Winnipeg reservoir has been expanded to the point that it now can hold 8.8-billion litres of water, the equivalent of a 20-day supply, according to the city of Winnipeg.
The February 1, 1919, Free Press reported figures on the performance of the aqueduct: “Eighty-five million gallons (386.4 million litres) would fill Portage Avenue between the building lines from Main Street to Sherbrook Avenue to a depth of 20 feet (six metres); the contents of the (Deacon) reservoir ... combined with the contents of the reservoir now owned by the city of Winnipeg (McPhillips), would fill this same area to a depth of 63 feet (19.2 metres), or to the height of the fourth story (sic) windows.”
Chief engineer Chace explained at a meeting of the Winnipeg Rotary Club on October 2, 1918, how the water was to be piped under the Red River. “As you know, we broke through the last portion of rock bore under the Red last Saturday night. The bore, which was made through the uneven starts of limestone rock, will be lined with cast-iron pipe 60 inches (1.524 metres) in diameter, the joints of which will be caulked from the inside. On the St. Boniface (then a separate municipality) side this will be connected with the 66 inch (1.678.4 metres) reinforced concrete pipe forming that portion of the aqueduct; and on the Winnipeg side it will be joined up with the 48 inch (1.219.2 metres) reinforced concrete pipe running along Pacific Avenue to McPhillips Street (then the site of the only reservoir within the city’s boundaries).
“After the pipe is laid along the (24-metre-deep) tunnel, we propose filling in the overbreak, which has been fairly regular, by pouring in concrete, in its thin state, from the surface of the ground down a shaft, guiding it by pipes which can be shortened as the overbreak is gradually filled.”
The scope of the project was such that a motion picture was advertised to run at the Dominion Theatre in February, “showing the construction, engineering, works, aqueduct and district from Indian Lake (sic) right through to Winnipeg.”
The advertisement said every resident of the city should view the film to obtain “a proper understanding of the importance and magnitude of Winnipeg’s great water scheme. It ranks among the major undertakings of the world.”
By the end of March 1919, the aqueduct was essentially completed.
Thomas Deacon, whose unfaltering promotion of Shoal Lake as a water supply for Winnipeg led to the construction of the aqueduct, said he was “prepared to use Shoal Lake water as fast as it can be supplied to me ... When the water has flowed long enough through the pipes to clean them properly and it is real Shoal Lake water we are getting, it will be found to be faultless. The water should undoubtedly be turned on and opportunity given the public to decide for themselves ... whether they like it or not.”
On March 27, 1919, at the western entrance to the Red River tunnel, a lever was thrown releasing the water into the last section of the aqueduct. The project was declared completed on Saturday, March 29, although Shoal Lake water was not available for public consumption until April 5, and the official opening ceremony was not until September 9 when the Prince of Wales visited Winnipeg.
Initially, there was a great deal of skepticism about the new water supply brought on by tests which showed the presence of micro-organisms, such as freshwater cyclops, a type of crustacean. However, none of the tiny organisms were present in any great quantity, nor were they harmful to humans, and as a result the new water supply was soon receiving good reviews.
In mid-April, the Winnipeg Building Owners’ Association declared its satisfaction with Shoal Lake water.
H.S. Patterson of the association said the arrival of Shoal Lake water was one of the finest events in the history of the city.
An April 30, 1919, Free Press editorial rejected the criticism as unfounded and called the project “a credit to the men who conceived of it and carried it through ... as time passes the benefits it brings to the community will be fully appreciated.”
The benefits of Shoal Lake water were anticipated even before the taps were turned. Robert Waugh, the head of the GWWD board, said the combination of cheap city-owned hydro-electric power and water from the aqueduct will allow the Winnipeg Board of Trade to pursue “colossal” industrial prospects from around the world.
He said Winnipeg had “entered the class of world cities” as a result of the foresight shown to build the aqueduct and a hydro-electric generating station at Pointe du Bois in 1911 along the Winnipeg River.
With the completion of the aqueduct, he said, delivering clean soft water and the availability of cheap power guaranteed Winnipeg’s future industrial, commercial and municipal growth.
A study by the Winnipeg Board of Trade in 1919 concluded direct benefits of the new water supply included savings on soap, cisterns, chemical softening plants and corrosion. Prior to the advent of water supplied by the aqueduct, industrial expansion was hampered by the highly-mineralized hard water from artesian wells which promoted corrosion and incrustation in boilers that heated and powered manufacturing facilities.
“It is as magnificent a supply as that of the city of Glasgow, or of Los Angeles, or of New York,” said Professor Charles Schlichter of Wisconsin after hearing about the aqueduct’s completion. His 1913 report commissioned by the city recommended Shoal Lake as the source of Winnipeg’s water supply.
“None of these cities possesses a supply more wholesome or sanitary, and few indeed enjoy a supply of such delightful softness ... you need not fear comparison with any supply of any place on earth,” he added.
On a special platform erected in front of city hall on September 9, Mayor Charles Gray asked Edward, the Prince of Wales (later King Edward VII), to press the electric button to “officially open our $16-million water system.”
Upon pressing the button, water from a fountain behind the platform spurt forth to appreciative cheers from the audience.
The Greater Winnipeg Water District, which included the city of St. Boniface, the town of Transcona and the municipality of St. Vital and parts of the municipalities of Fort Garry, Assiniboia and East and West Kildonan, now had a water supply equal in quantity and quality to the city of Glasgow, which then had a population of one million in comparison to Winnipeg’s 250,000 citizens, Gray told the prince.
“The citizens are proud to have the final act, the official opening of this, their greatest enterprise, performed by the future King of the British Empire,” said Gray.
Although Gray pegged the final cost of the aqueduct at $16 million, the actual total was nearer $15.5 million — $2.5 million more than the original projection in the 1913 report — to build one of the most significant waterworks projects of the 20th century. To replace the aqueduct today, the estimated cost would be approximately $1 billion.
“The original project was a remarkable engineering and construction feat for its time,” said the authors of the article Winnipeg’s Aqueduct, “reflecting the daring and imagination of city leaders, water works engineers and contractors.
“Its conception and implementation lead to several important technological innovations and improvements in construction techniques which were ahead of their times. Underdrains to minimize sulphate attack, precise concrete mix designs, the application of soil mechanics well before the development of classical bearing capacity formulae and hydraulic design before the introduction of the Manning formulae (used to calculate water flow driven by gravity) ...”
Although the aqueduct reflected the groundwork laid by Roman engineers centuries earlier, it was in its own right a profound achievement of design and construction that remains in service to this day, providing Winnipeggers with pure and soft drinking water.