| Hogs Back - Locks 11 and 12
| location map | lockstation information |
Hogs Back, originally known as Three Rock Rapids, was a set of rapids which marked the end of a seven-mile (11.3 kilometre) stretch of shallow water. These rapids were about 2,000 feet (600 m) in length with a drop of 6 feet (1.8 m). The name Hogs Back comes for a ridge of limestone cresting in the channel, looking like the backbone of a hog. Upstream from Hogs Back was another extensive set of rapids known as Three Island Rapids (now under the waters of the head of Mooneys Bay). From Hogs Back Rapids, the elevation difference to the Ottawa River was over 100 feet (30.5 m), travelling through rapids and shallows until it went over the 30 foot (9.1 m) Rideau Falls into the Ottawa River. Upstream of Three Island Rapids was a section of calm water, known as Captain Wilson's still water, named for Captain Andrew Wilson, R.N., who had settled there.
Samuel Clowes' 1824 recommendation was to bypass Hogs Back entirely. Clowes' plan called for an artificial canal cut, leaving the Rideau River near present day Billings Bridge, and heading overland, on the east side of the River, to re-join the Rideau at Captain Wilson's still water, just south (upstream) of the Three Island Rapids. Seven locks at the Billings end were to provide the required lift.
Colonel By rejected Clowes' plan to take the canal to Rideau Falls early on, since a route on the east side of the Rideau River would have required a great deal of rock excavation. By's plan was for an overland route on the west side of the Rideau River (mostly gravel, very little bedrock). His original concept did have some elements of Clowes' plan since it didn't include a dam, but rather canal cuts to bypass the rapids (this plan is detailed in the Ottawa Lockstation section). However, that plan was soon abandoned, likely due to the difficulties in excavating canal cuts in bedrock and a clearer focus on creating a slackwater navigation system. So, he adopted the plan of intersecting the Rideau River at the head of Three Rock Rapids (Hogs Back), placing three locks in this location, and building a large dam at the head of those rapids in order to flood the rapids above Hogs Back and put water into the locks and canal channel leading to the Ottawa Locks.
Tenders were released for the construction of three locks, each with 10 feet (3 m) of lift, plus a dam across the Rideau River, some 45 feet (13.7 m) in height and 240 feet (73 m) long. The idea for the dam was to convert "the present seven miles of shallow Rapids into a sheet of Still Water, and thereby save the expense of excavating the Canal for that distance." (Letter from Colonel By, May 1827).
Building of the Locks
The contracts for the locks and dam were awarded to Walter Fenlon. Philemon Wright and Sons were awarded the contract to build the coffer dam "to turn the water around the Dam at Hoggs Back …" By the time the contracts were awarded, By had changed his plans, moving two of the locks down to Hartwells. Only one lift lock would be needed at Hogs Back. However, worries about spring flooding and ice damage led By to add a guard lock at Hogs Back. A guard lock is a non-lift lock, placed both to protect the lock(s) behind it and to be used as a lift lock in times of high flood. Originally, several guard locks were planned for the Rideau but it was only at Hogs Back that one was built.
The main story at Hogs Back is the building of the dam. Originally a stone dam had been proposed. The way such as dam was built was to lay dry stone (keywork) on the downstream side of the dam. Against that would be a layer of clay puddle, which could be up to 20 feet (6.1 m) thick. Clay puddle is clay mixed with coarse sand or fine gravel, wetted and then chopped, beaten and kneaded into a consolidated mass, about two-thirds of its original volume. If kept in an area where it would remain wet (i.e. below the water table) it would remain completely watertight. This clay puddle would form the impervious core of the dam. On top of the clay puddle would be laid earth and gravel, sloped at a standard angle of repose (usually 2.5:1). The finished dam would have an almost vertical back face (usually inclined at a 1:10 ratio) with a gently sloping front face. At Hogs Back, a coffer dam was to be erected ahead of the work, to keep the water away from the section of the dam currently under construction.
Fenlon started work on the dam in the summer of 1827. By 1828, he had raised the dam 37 feet (11 m), and had extended it across the channel to within 60 feet (18 m) of the far bank. However, an unexpectedly early rise in the Rideau in February 1828 washed much of the dam away. Repairs were made but rising flood waters again destroyed much of the work on April 1, 1828.
On June 18, 1828, Walter Fenlon wrote to Colonel By: "I find that I cannot possibly continue the Work at the prices that I am at present getting according to my Contract and I am the looser to a great amount on what I have already done. My humble prayer at this time, is, that Government would take the job and release me from all claims on the Contract. I trust I shall be allowed an estimate on what I have done in preparation for carrying on the work, and my losses I submit to the Consideration and discretion of the Commanding Officer."
It appears that it was not until the fall of 1828 that Fenlon was released from his contract. It was noted by Colonel By and the on-site overseer, Capt. J.C. Victor of the Royal Engineers, that P. Wright and Sons had taken over part of Fenlon's contract, a new contract being awarded to Wrights on November 1, 1828, and in addition, that masons of the Royal Sappers and Miners were employed in building the arch keywork of the dam. By noted that "it will require great exertion during the whole of this winter to raise the arch Key work to a sufficient height to resist the spring floods;…"
By mid-November 1828, By had both companies of Sappers and Miners as well as 300 labourers at work on the dam. While building the dam through the winter of 1828-29, they ran into a problem not encountered in England. The cold weather allowed frost to penetrate deep into the works. Frozen earth and clay didn't allow the proper compacting of the puddle and unbeknown to By and his men, the dam was not watertight. Rising spring floodwaters placed hydraulic pressure on the dam. Water found its way under the dam and started to erode a channel through the works. Since the frozen material was holding up the top of dam there was no initial settling of the ground, no indication that anything was wrong.
On April 2, 1829 the leak was noticed when unfrozen material of the apron slumped below the frozen layer. Work was immediately started to try to stem the leak by throwing material (timber, earth) into the leak and by clearing out obstructions in the bywash to reduce the pressure on the dam. On April 3, 1829, the keywork of the dam failed. By provides a vivid description of this, stating that he "was standing on top of it [the dam] with forty men employed in trying to stop the leak when I felt a motion like an earthquake and instantly ordered the men to run, the Stones falling from under my feet as I moved off." Since the earth was frozen, an eyewitness observed that the earth of the dam stayed suspended for a time over the "leak" which was now a 50 feet (15 m) wide channel of rushing water, until eventually the sides were washed out and the whole section of dam in this area collapsed into the roaring river.
After the failure of the dam, several surveys were done to see if an alternate route for the canal could be found. It was concluded that no alternative existed, that the dam would have to be remain at Hogs Back. One of By's superiors admonished him to construct "the Dams perfectly impervious to water" to which By replied, "I beg to state that on that principle I have acted from the commencement of the works."
Wright's timber cribwork cofferdam had held, and when spring flood was over, By instructed Wright, with the assistance of the Sappers and Miners, to complete the cribwork dam across the river. An interesting addition in May 1829 was the construction of a rail road, some 1160 feet (350 m) long, from the quarry to the dam. This was done to reduce expenses of moving stones from the quarry to the work site.
The timber cribwork construction proceeded smoothly and the dam was raised to a height of 45 feet (13.7 m). By had originally planned the dam at Hogs Back, as well as those at most other lockstations, to be an overflow dam, but after his experiences with the Rideau River in spring flood, he changed most to non-overflow dams, adding a waste water weir, a separate control dam and channel by which excess water could bypass the main dam and locks. In fact during the construction at Hogs Back, with each subsequent failure of the dam due to rising flood waters, the waste water channel (the location of present day Hogs Back Falls) was expanded in width and depth. The dam and weir were completed by the spring of 1830.
The locks proved to be much less of a challenge than the dam. Since this was the spot where the artificial channel of the Rideau Canal and the Rideau River would meet, By was worried about damage to the lock from flooding, and what might happen if the entire Rideau River decided to flow down his newly constructed canal cut. To prevent damage to the lock, he built a guard lock in front of the single lift lock. One purpose of the guard lock is to prevent damage, primarily from flood water and debris, to the lift lock. It can be used in times of high flood water as a lift lock, so that the lift lock behind it doesn't have to bear the full brunt of the high waters. This is the only spot on the whole of the Rideau system where a guard lock was built. The floors of both locks were built using inverted masonry arches. The lift of the lock was 14.5 feet (4.4 m).
|Upper Guard Lock at Hogs Back
showing the swing bar/crab system that replaced the original endless chain crab in about 1835 (see Appendix 4)
photo by: Ken Watson, 1999
|Hog's Back, ca.1845
John Burrows, watercolour over pencil, Archives of Ontario
A view of the locks at Hogs Back, the dam and weir. The remains of the failed stone keywork backing the dam are still visible.
Through the Years
A defensible stone lockmaster’s house was first built here, on the east side of the lock, in about 1838. It was torn down and a new, wood frame building was built on the foundation of the original lockmaster’s house in 1907. This building was moved to the west side of the lock in the 1950s.
In 1886 a timber swing bridge was built across the guard lock and a fixed bridge built across the waste weir.
Although By was well aware of the dangers of spring flood, he was caught by surprise by the amount of debris, such as uprooted trees, that came down the Rideau with each spring flood. He placed wooden booms out in front of the dam and lock to try to catch this material before it could collide with the works. By also had some of his Sapper and Miners on guard duty at these booms "to prevent the Rafts Men destroying them..." a reference to timbermen who would raft their logs down the Rideau and were not too happy with having their route blocked with log booms. Once the canal was complete, these rafts of timber were locked through the locks just like any other vessel.
Even with timber booms, ice and floodwater took their toll on the structures at Hogs Back.
In 1841, the woodwork on the east side of the dam was undermined and had to be repaired in haste with stone filled cribwork in order to save the dam from collapse. In 1862, the greatest flood ever known to that time on the Rideau was experienced. It washed out the waste weir and opened a 200 foot (61 m) wide by 32 foot (10 m) deep hole in the dam. Prompt action managed to save the dam. After this close call, a new bulkhead consisting of six openings, each 20 feet (6 m) wide, was built. However, ice and logs carried by spring floods continued to do severe damage on an annual basis. In 1877, a new bulkhead was built just a bit downstream of the existing bulkhead, which acted as a coffer dam during construction. This new bulkhead had five, 20 foot (6 m) openings.
Problems weren't restricted to the dam; in 1868 the west wall of the lock developed a severe bulge and vessels were cautioned to use the lock at their own risk. In keeping with the government's frugal policy of canal maintenance expenses, a request to rebuild the wall was turned down in favour of a jury-rigged repair of metal rods and strapping. It was not until 1901 that the west wall was fully rebuilt and 1904 that the lower west wing wall was rebuilt.
Problems with spring flooding continued. In the spring of 1885, a field of heavy ice, about 10 acres (4 hectares) in size, struck the dam and caused severe damage. The locks were closed until June 23 of that year while repairs were made. In 1891 the dam again sustained severe damage. At this time, concern was raised by downstream residents, and an inquiry was held. The inquiry supported recommendations by Superintendent Wise for a major reconstruction. This was done in 1892-93.
Today the dam is barely recognizable with parkland on the upstream side and a wooded slope below. An interesting side note is that the falls we see today at Hogs Back are man made. The canal dam raised the water of the Rideau River by 41 feet (12.5 m) and the water from the weir is actually flowing through an excavated weir channel. This created the falls that we see today (Prince of Wales Falls). The original rapids (Three Rock Rapids), now mostly buried under the dam, only had a drop of about 6 feet and were navigable by canoe.
|Aerial View of Hogs Back
showing locks, dam and waste weir
photo by: Parks Canada
The lockstation can be seen on the left, with the road crossing the dam in the centre, and the large weir on the right. The serene navigation channel of the Rideau Canal on the left contrasts with the falls and rapids of the Rideau River channel on the right.
The Lockmasters to 2000
Although Thomas Jenkins, corporal in the 15th Company of Royal Sappers and Miners was proposed by Colonel By in 1831, the first listed lockmaster was William Mitchell who was shown in 1845 as having served as lockmaster for 14 years. He was succeeded in about 1857 by Michael Gleeson. Gleeson retired in October 1882. His successor, J.K. Read, was one of five lockmasters discharged early in 1896, apparently the result of the Liberal election victory. Unlike the other lockmasters, he was not rehired in the spring of 1897, and in May, Timothy Bayne was appointed lockmaster. He resigned in October 1911 and was succeeded by Alexander Montgomery of Manotick who retired in July 1924. Montgomery was followed by Arthur Dale from 1924 to 1950; Leslie J. Watt from 1951 to 1960; J.M. Sugrue 1961; Aurel Caron from 1962 to 1976; Walter Bown (with Hartwells) in 1977; Marcel Belanger from 1978 to 1984; Andy St. Amour acting in 1982; Al Berger acting in 1983; Bruce Bennet acting in 1984; Al Berger from 1985 to 1991; Jim Gibbs acting from 1987 to 1988; John Cooke from 1989 to 1999; Jenny Aikman acting in 1999 and Jacques Ferland from October 4, 1999.
For those with an interest in the specifics of a Rideau dam building contract, here is an excerpt from contract made with Walter Fenlon in the spring of 1827.
"Before the undersigned J.M. Mondelil Esquire His Majesty's Notary for the district of Montreal and his colleague Notary Public for the province of Lower Canada, both residing in the city of Montreal.
Appeared Charles John Forbes Esq., Deputy Commissary General, residing in the city of Montreal acting for and on behalf of our Sovereign Lord the King of the one part. And Walter Welsh Fenlon of Montezuma in the state of New York, Civil Engineer, of the other part, which said parties have made and entered into the following agreement, to wit, the said Walter Welsh Fenlon for the several considerations hereinafter mentioned hath covenanted, contracted, and agreed, and by these presents doth covenant, contract, agree, and undertake, bind and oblige himself to do, execute, perform, and complete within the space of time of two years, reckoned from and after the day of the date of these presents, in a good substantial master and workmanlike manner, the works hereafter mentioned and specified to wit,
lst to Construct a large Dam across the Rideau River, in the Province of Upper Canada, at a point called the Hogs Back, distant from Entrance Bay on the Ottawa River about 6 Miles.
2ndly To Build and form three locks at the back of the said Dam on the Nepean side of the river ... all which said works are to be done and completed within the time aforesaid in conformity to specifications thereof arrived to these present, ... The Ashlar Stones for the side walls of the said locks to be not less than two feet six inches long nor less than twenty inches Breadth of bed, and from nine a half inches to sixteen inches thick, the beds to be done in the very best manner with header and Stretcher alternately. The face to be cut with good fair chissel draughts arrived and required and hammer-picked between these draughts. The beds are to be levelled off the face with bevells furnished for the purpose by the Royal Engrs, with good chissel draughts all round, and rough hammer picked between, the front draughts to be three inches Broad, the joint to be squared at least ten inches back the hollow quoins to be three feet eight inches on the face, to be two feet eight inches breadth of bed, and from nine and a half inches to sixteen inches thick, to be done in the same manner as the ashlar only the beds are to be square off the face, and the hollow for receiving the hedpost of the Gate, is to be as fair and clean chisselled out as possible, and cut to a mould to be furnished by the Royal Engineers. The beds of the hollow quoins to be square off the face with chissel draughts all round and hammer picked between both beds to have the front draughts three inches broad with the joints to square back full. The inverted arch stones to be two feet long by two feet deep if required and from nine and half inches to sixteen inches in thickness, to be cut to a mould furnished by the Royal Engineers. One edge of the stone to be clean chisselled, the sides to be draughted all round and hammer picked out between, with the front draughts three inches broad, the other edge of the stone, which is the bed on which it is to be set, is to be fair draughted all round and hammer picked between, the joints are to be square full back the whole breadth of the stone. The Ashlar for the back of the lock Gates etc not to be less than two feet length of face, two feet eight inches breadth of bed and from nine and a half inches to sixteen inches thick to be cut in the same manner as the ashlar for the side walls of the Locks only the beds to be cut to the square and the joints squared back at least fifteen inches and the face of the stone is not to be hollowed as that mentioned for those for the side walls. The coping stones for the walls not to be less than two feet six inches length of face and two feet eight inches in breadth, to be cut, the perpendicular face the same as the Ashlar, the horizontal face or upper bed to have good draughts round and picked out between, with the front arris rounded off and made to a bevel furnished by the Royal Engineers, the lower bed with draughts round, and hammer picked between. The whole of the said cut stone to be done after a most workmanlike manner, to the entire satisfaction of the said Commanding Royal Engineer Lieut. Col. By, or other officer appointed to superintend the said works ... It is also agreed by and between the said contracting parties, that if the excavation for the said locks and line of canal aforesaid affords a good quality of stone for building the said locks, the said Walter Welsh Fenlon doth hereby agree and promise to take and use the same at a fair valuation, the amount whereof to be deducted from such monies as he shall be entitled to recieve [sic] in and by virtue of the present agreement.
The present contract and agreement is thus made for and consideration of the rates and prices following to, wit.
For constructing the Dam across the Rideau River aforesaid in manner as above stipulated one shilling and ten pence British Sterling money per Cubic Yard being the average price of the whole, that is to say for arched Key Work dry rubble masonry and pulverized stone; For the building and constructing the above three locks, eleven pence half penny said sterling money for each and every Cubic foot of masonry, it being hereby expressly understood and agreed, that the measurement thereof shall only be made after the same shall be built in the wall and the whole thereof to be measured cubically as aforesaid and paid accordingly;"
- above quote reprinted from Parks Canada, Manuscript Report 193 by Karen Price, 1976, pp.100-102. The original quote was referenced as: Public Archives of Canada, RG8, Vol. 48, pp. 104-109.