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Sidney GS


Next station after the Big Chute was Sidney. Located on the Trent River, about five
kilometers from Trenton, Sidney GS was named after the adjacent township of Sidney.
The Trenton river is part of the historic Trent-Severn Waterway which was originally built
to provide transportation of good across 386 km in Central Ontario linking the Bay of
Quinte with Georgian Bay.

One of the longest-serving hydroelectric facilities in OPG’s fleet, Sidney GS went into
service in 1911. OPG’s predecessor company, Ontario Hydro, acquired the station in
1916 from its original owner, the Sidney Electric Power Company. Prior to the
redevelopment the station had four 1 MW vertical double runner Francis units. They
were replaced with four horizontal Kaplan 1.5 MW turbines requiring extensive structural
modifications to the existing powerhouse. This work increased the station’s capacity,
efficiency, and extended its operating life.

Kaplan units had to be set on the lower elevation that the existing Francis units, thus
necessitating a 3.5 m excavation below existing foundation level. In addition to
excavation a substantial work for the removal of existing concrete were required.
Each hydro site has its own challenges. This is the beauty of the Hydro design, you can
never find two identical sides, and all of them are always very different and in order to succeed
you have to be a very creative Engineer. There was also one very interesting characteristic for
Sidney and Seymour: concrete was very strong compared to some other sides built the same
time. I was lucky enough to meet a very smart old Engineer from Ontario Hydro, the technical
Supervisor for Bellville District- Peter Richardson, who knew a lot about the history of Hydro
projects in Ontario and he told me that these sites were built by a very smart Engineer who was
a pioneer in the development of the right ratio of water to cement for concrete structures as
well as a right methods of pouring concrete.

Sidney had a fore bay before Power House with the trash rack structure in front of it. Whitney
Hall decided to use this structure for the upstream coffer dam because it would be very costly
to use a conventional coffer dam, Trent River was very deep in the area, we had to find an
alternative solution for coffer dam and to use this structure was really very logical-but we did
not expect so many technical problems with it. The trash rack structure was not design for full
hydro static pressure after dewatering the fore bay; posttension anchors had to be installed in
every pier. We had to cut opening in the slab to insert gates through it and install the guides for
gates by divers under the water. Gates were inserted in guides -steel welded channels
connected to the piers by anchors under the water. Divers had to drill in the concrete for HILTI
HSL mechanical anchors, and then install the guides. All work had to be done with very high
precision otherwise gates (18ft by 18ft) would not fit. This work was absolutely unique, even
many years later I was approached by few construction companies with the questions about it.
I will never forget the day when the fore bay was dewatered. I was on the side at 4AM, the
contractor was following my strict order to lower water level by only 6” per half an hour, after

few hours we started to go faster, and at 4:00 PM it was done! Big relieve for me, of course I
was very worried.

Our very unusual coffer dam worked really well through all construction period, site was
commissioned at the end of year 1993 and then my big problems started. We did not remove
intermediate 4 ft thick concrete walls between the units, unfortunately they were very badly
cracked and we got very big water seepage into the power house. We had to go through a very
long and expensive chemical grouting of the concrete walls to stop the leakage. Few different
contractors unsuccessfully tried to solve the problem, but only Hank Aho from Trow consultant
found the right solution- to drill very deep and in few days power house was dry!

There is another site very similar to Sidney Frankford GS that sits just eight kilometers away
from Sidney and went into service two years after Sidney. KST worked on retrofit of
Frankford GS, all four new horizontal Kaplan units were delivered and KST prepared
drawings for tender; some preliminary work was done on the site including stabilizing of
the tailrace training wall by the installing of mechanical (solid bars) post tensioned rock
anchors placed at 5 ft on center.

During under water investigation substantial erosion damage was found at the bottom of
foundation of the intake structure. It was fixed with pouring tremie concrete and
pressure grouting after.

Very unfortunately despite the full preliminary design done the construction was
cancelled by Ontario Hydro.
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