John Hart Generating Station Replacement Project. May 2017 Community Construction Update Report #47

Size: px

Start display at page:

Download "John Hart Generating Station Replacement Project. May 2017 Community Construction Update Report #47"

Alfred Banks
6 years ago
Views:

by: Stephen Watson, BC Hydro (O) 250-755-4795 or (C)

1 John Hart Generating Station Replacement Project May 2017 Community Construction Update Report #47 Prepared by: Stephen Watson, BC Hydro (O) or (C)

Project Status The tailrace tunnel rock excavation was completed at the end of April, a significant milestone; First stage concrete (the main structural components of the powerhouse) was completed,

2 Project Status The tailrace tunnel rock excavation was completed at the end of April, a significant milestone; First stage concrete (the main structural components of the powerhouse) was completed, marking another project milestone. Placement of second stage concrete (that embeds the major mechanical equipment after installation) is underway. 11,800 cubic meters of concrete, enough to fill almost five Olympic-sized swimming pools, has been placed in the powerhouse; Water intake trashracks (prevents debris from entering the tunnel) measurements and modifications are complete and trashracks now installed; Work continues on the low level outlet trench (downstream) with blasting and mucking; Drilling and form ties within the intake tunnel under the John Hart dam are complete, including the concrete placement; In the power tunnel, draft tube rebar installation continues and water bypass outlet liner welding is scheduled to be completed by the end of the month; Power tunnel rock excavation has passed 1,444 metres of the total 1,575 metre long tunnel. The tunnel is about 92% complete; and Removal of the muck rock within the surge chamber is complete and ready for final inspection. The gate slot excavations from the above gate gallery are complete. The tailrace tunnel rock excavation, from the powerhouse to the tailrace outlet, is complete.

Project Schedule Powerhouse cavern view from the service tunnel.

for the summer season: Wednesday to Sunday, 10 am to 5 pm; May: Water bypass

run out of the powerhouse, across land and connect to the existing BC Hydro John

work to begin at surge tank site; July 9: John Hart project community site event;

3 Project Schedule Powerhouse cavern view from the service tunnel. May 18: The John Hart Project Interpretive Centre is now open five days a week for the summer season: Wednesday to Sunday, 10 am to 5 pm; May: Water bypass outlet steel liner installation continues; June: Cable tray work power cables to run out of the powerhouse, across land and connect to the existing BC Hydro John Hart substation; June: Begin process for removal of cofferdam; June: Concrete work to begin at surge tank site; July 9: John Hart project community site event; July: Power tunnel rock excavation complete; and July: Power tunnel floor concrete placements and grouting.

4 Construction Pictures Cofferdam And Water Intake Maintenance Gates The John Hart dam and the steel pile cofferdam, and the below pictures show the installation of the trashracks. 4 Tunnelling work under the John Hart dam.

5 Cofferdam Removal And Excavation Of Rock The removal of the cofferdam is a significant phase in the completion of the new water intake structure, as the maintenance gates are now ready to safely hold back the water once the cofferdam piles are removed. After the piles are removed, the intake approach channel will be drilled, blasted and excavated to provide a clear path for water to enter the intake. These stages will take place on land with cranes and excavators, as well as from a barge for drilling and loading explosives. This is the sequence of work: 1. The inside of the cofferdam is filled with water and the gates are wet-tested for leakage to ensure they are watertight. 2. When the gates pass the leakage test and have proven their capability, the cofferdam is pumped dry and protection for the structure is installed prior to filling with water again. The south and west sides of the cofferdam bracing is then removed and, using certified divers, the steel pipe piles are cut underwater at the rock surface. The cut pieces are salvaged to shore with a crane. 3. Next comes developing the intake approach channel. To do this, the rock plug is removed by drilling and blasting: Blast holes will be drilled and loaded from a barge, and detonated to remove the rock plug. Special blast protection curtains will be used to protect the new intake infrastructure such as the trashracks and gates and mitigate impacts to fish in the area. To minimize risk to fish, a pre-blast warning charge is set a few seconds before the main blast, scaring fish away from the area. Post-blast, silt curtains will be lowered into the water to minimize the risk of turbidity entering the reservoir, and other water management activities will further isolate the City of Campbell River water supply and direct flow away from the water intake. 4. After the blast, rock is excavated within the silt curtain contained area and utilized by the project or hauled off site. 5. Finally, once the approach channel is ready, the silt curtains are removed and a debris log boom and safety barriers will be installed. 6. Throughout this work, environmental monitors will be on site to conduct water quality testing and assist with additional mitigation work, if required.

6 Concrete form work for the water passage under the dam to the Construction Overview Rock Removal power tunnel and low level outlet. 6

7 Construction Overview Rock Removal Low level outlet works. Power tunnel shaft. 7 View from top of John Hart dam.

8 Construction Overview Rock Removal 8 Placement of the first section of low level outlet liner.

about every 250 metres along the power tunnel.

9 The picture below and the right show the creation of one of the many Construction Pictures Power Tunnel muck bays located about every 250 metres along the power tunnel. These bays create space for equipment and rock debris. Muck bay. Power tunnel. 9

10 Construction Pictures Power Tunnel Drilling in the muck bay. 10

11 Looking upstream in the power tunnel. Construction Pictures Water Bypass Inlets On the right, the three entrances to the water bypass inlets are visible. 11

12 Construction Pictures Power Tunnel Roughly the same view as the last page, a few weeks later, of the power tunnel with concrete formwork in place. 12

13 Construction Pictures Water left, and Bypass water inlet #3 beside Inlets the excavator. View from power tunnel of water inlet #2 to the 13

14 View down Construction Pictures Water Bypass Inlets turbine/generator water inlet #1. 14

15 Construction Pictures Water Bypass Inlets View towards the power tunnel within turbine/generator water inlet #1. 15

16 Construction Pictures Powerhouse Insert photo: Turbine/Generator #3. Take a 360 virtual tour of the powerhouse: /johnhart/ 16 View of powerhouse area from main access tunnel. Powerhouse cavern view from service tunnel.

17 Construction Pictures Powerhouse All the generator floor concrete has now been placed. 17 May 4 picture

18 Construction Water bypass facility. Pictures Powerhouse 18 View of powerhouse area from main access tunnel. May 4 picture

19 Construction Pictures Powerhouse Powerhouse view from main access tunnel. 19 View of powerhouse area from main access tunnel. May 4 picture

20 Construction Pictures Surge Chamber Delivering a section of Turbine/Generator #3 water outlet formwork for the concrete placement. 20

21 Construction Pictures Surge Chamber The water outlet from Turbine/Generator #3. 21

22 Construction Pictures Surge Chamber Surge chamber and removal of rock muck. Insert picture shows view of digger from the above gate gallery slot. 22

23 Construction Pictures Surge Chamber A loader places some rock muck from the surge chamber into a truck. View from tailrace tunnel looking upstream. 23

24 Construction Pictures Surge Chamber Tailrace tunnel looking downstream to the outlet. 24

25 Construction Pictures Surge Chamber The tailrace tunnel blasting and rock removal is now compete. View of the steel stop logs. CTV-VI and CHEK News stories on the excavation milestone: mobile/video?clipid=

26 View from the tunnel outlet back up the tailrace tunnel. Construction Pictures Surge Chamber 26

Environment With spring giving way to summer, plants and animals are emerging. Crews are watchful for invasive vegetation and discouraging animals from making their homes in active work areas.

27 Environment With spring giving way to summer, plants and animals are emerging. Crews are watchful for invasive vegetation and discouraging animals from making their homes in active work areas. Crews are covering forms and equipment at the lower site laydown area to prevent nesting while inspections for signs of nesting activity continue regularly in other key work areas. Restoration of the slope failure beside the Millennium Trail last November, on BC Hydro property, is essentially complete (shown below). Fallen trees/debris were used to reinforce the steep sections of the exposed slope and to create habitat diversity. Scotch Broom control measures are being implemented throughout the site. A number of wildlife observations have been made a sure sign of spring: A tree frog and a sideband snail were relocated; An owl ball (likely from a barred owl) was found; and Crews have also noted deer and evidence of cougar activity. Blasting is still occasionally occurring for the low level outlet trench and as part of the power tunnel excavation, but no environmental concerns have emerged.

28 People Profile Colin Orr About Colin Background: Since joining the Operating Engineers in 1977, Colin has been operating equipment in the construction industry. Cranes caught his attention early on and in 1984 he obtained his trade ticket. Home: Colin grew up in Hamilton, Ontario. Following the auto-industry downturn across southern Ontario he pursued work in construction. During the oil boom, Colin and his wife moved westward to Alberta where he worked in the oil and gas industry with companies such as Syncrude and Suncor. In 2006, they moved a bit further west, purchasing a hobby farm in Sayward. Hobbies: When not at work, Colin is busy on his hobby farm where he gardens and raises sheep. Project Responsibility: Colin operates the 165 ton crane at the new water intake works for ASL-JV. The John Hart project is a great opportunity to finish my career closer to home.

Construction Point Of Interest Each month, BC Hydro and InPower BC will provide a construction fact, occurrence, or situation.

operating range. They are also specially designed for energy dissipation.

29 Construction Point Of Interest Each month, BC Hydro and InPower BC will provide a construction fact, occurrence, or situation. Water Bypass Operating Valves The project s three water bypass operating valves (BOVs), located in the powerhouse area, are plunger valves that will allow water flow rates to be precisely managed at all times. Unlike butterfly valves and other isolating valves which are primarily operated in the fully open or fully closed positions, the BOVs are designed for sustained, accurate flow releases over the full operating range. They are also specially designed for energy dissipation. When water is needed to pass through the BOVs and not through the turbines (where all that energy would otherwise be converted through power generation), the water must still be dissipated to achieve similar flow conditions in the downstream tunnel and river channel. Inside the valve there are several internal pipe sleeves/layers that each have a closely spaced pattern of holes like a sieve. A solid plunger (also called a piston) seated inside the valve can be moved forward or backward to change the amount of cylindrical sieve pattern that is open versus blocked to allow the flow discharge to be adjusted. In the open sections of the sleeve, the water must force its way through the multiple layers of holes/sieves, and this dissipates the energy of the water as it passes through the sieve. The many jets of water forcing through these cylindrical sieves all point radially towards the centre of the valve, colliding with each other resulting in further energy dissipation. Generally: VAG fabricated the BOVs at its plant in Mannheim, Germany; They are manufactured using a single, steel casting; These are the largest plunger valves produced by VAG, and amongst the largest in the world; Their purpose is to control and dissipate the energy in the water flow when required to bypass water around the turbines; and BOVs will protect downstream fish habitat (one of the three overall project drivers) by allowing BC Hydro to maintain a constant river level downstream of the project during a shutdown of one to all three the generating units.

John Hart Generating Station Replacement Project. November 2017 Community Construction Update Report #53

John Hart Generating Station Replacement Project November 2017 Community Construction Update Report #53 Prepared by: Stephen Watson, BC Hydro (O) 250-755-4795 or (C) 250-616-9888 Twitter: @Puntledge Email: