There are few facilities as notorious to work in as Toronto’s Ashbridges Bay T- Building or M-Building Pumping Stations. Sufficient to say, since the late 90’s, we have replaced or rehabilitated more than a few gates controlling flow through both buildings. In 2011, Gate Tech was asked to inspect gates tagged TSG-1 through TSG-7 located in the T-Building wet well & submit a technical report. (Original report; 22 pages based on 7 gates) For the purpose of this particular blog, our focus will be limited to gate TSG-7 since, as of this date, it is the only gate located in the well that has been rehabilitated. We started off on the project with a bit of a handicap; we were not allowed to enter the well & would have to proceed with a visual inspection only. Peering into the well during the course of our first walk around inspection there was little to be seen; the seven gates in question were located anywhere from 25 to 60 feet below the main operating floor. If you’re looking for more information on engineering services, click here.
We decided to tackle the inspection using a 1000 watt light standard and a quality camera equipped with a zoom lens. As luck would have it, the gate we were concerned about was the furthest (60’) down in the well, just beyond the ideal reach of our lighting. Consequently, photos of TSG-7 although in shadow, provided enough detail & enabled us to evaluate the physical condition of the gate and all accessories.
As fowled & dirty as this gate is, there was no reason to believe it should be replaced regardless of it’s appearance. All top wedges are in good condition, including the bronze installation bolts. Although the slide is choked with debris accumulated over a period of 42 years, we anticipate the slide and frame castings to be in good condition. Based on our experience, there are two factors causing operating difficulties with this gate;
- Debris contaminating the gate prevents the slide from fully closing.
- The upper portion of the operating stem is buckled resulting in considerable friction between stem guides and the steel sleeve in the floor slab.
Rehabilitation of Sluice Gate TSG-7
Rehabilitation could not begin without addressing a multitude of concerns;
1. Develop a method of work in a Class1, Division 1 confined space environment.
2. The facility 5 ton trolley crane will not reach gate TSG-7.
Consequently a fabricated steel structure will have to be designed, approved & installed to accommodate a manual trolley hoist 12.0’ above the main floor & positioned on the vertical centre line of the operating stem. Removal of the existing stem sections & guide brackets will be accomplished using the manual hoist. Hoisting & rigging to remove & re-install the sluice gate will involve a two stage lift; Begin by pulling the slide out of the gate frame with the manual trolley hoist, and passing it off to the in house overhead crane for lifting out of the well and from there depositing it down to a lower floor loading bay. Similarly, the gate frame will be supported using the manual chain hoist and jacked away from the embedded wall thimble and then passed off to the overhead crane, lifted out of the well and deposited in the loading bay.
3. Secure approvals for the following items on an ongoing basis;
a) Plant shutdowns
b) Man riding & extraction equipment
c) Hoisting & rigging procedures
d) Confined space entry
e) Explosion proof tools & equipment
f) Communication equipment
g) Supply & installation of fabricated steel work platforms at various levels within the wet well.
Preparations are underway to hoist the refurbished slide off a flat bed trailer & up into the main operating floor area. Note the 3M Scotchkote Powder coating & re-finished bronze hardware.
The gate frame has been hoisted out of the loading bay & up to the main operating floor. It will be lowered into the wet well once all the necessary preparations have been attended to & re-installed onto the wall thimble.
The gate has been installed in the well. We are in the process of installing sections of stem & the threaded couplings. Andrew is located 30’ below the top of the well; the gate is another 30’ down.
Robert & Andrew are in the process of installing an Auma electric actuator. Once the electrics have been connected, limit/torque switches set, the installation will be re-commissioned & returned to active service. If you’re looking for more information on engineering services on gate repair, click here.