Hydroelectric schemes prevent water hammer or damaging knocking in pipes etc. by the design of surge shafts, towers or tanks and / or expansion chambers, as close as possible to the pumps and turbines, connected upstream and / or downstream as necessary for every long power waterway tunnel.
So I am aghast to learn that there are reports of a significant water hammer problem with the extant botched Snowy 2.0 design 😳 but that instead of re-designing to include optimally placed surge shafts and tanks to avoid water hammer problems in the tunnels, Snowy Hydro and their contractors appear to have opted for expensive “state of the art” tunnel lining to try to cope with the water hammer high pressure transients, which is an expensive way to try to cope with a bad design problem instead of starting with a good design, as you should always do, of course.
Research Gate: Development of a tension-resistant single pass segmental lining in high pressure tunnels. The experience of Snowy 2.0 (Australia)
I began to smell a rat weeks ago when I started reading online WeBuild boasting about their “Force-Activated Coupling System”.
Then I noticed that whereas the feasibility study had 2 vertical pressure shafts and an upstream and downstream surge tanks and expansion chambers reasonably close to the pump-turbines –
– a recent WeBuild video and a previous Snowy 2.0 Newsletter May 2022 diagram shows an “inclined pressure shaft” at 25° and places the upstream 263m surge shaft about 2km away from the pump turbines where it cannot receive surge flow from a reducing generating flow down the inclined pressure shaft and that’s a very bad design, which is just asking for water hammer problems, in my opinion.
The correct design, as I have annotated Snowy Hydro’s newsletter diagram above to show, is to have the upstream surge shaft directly above the pump-turbine inlets, so the shaft would need to be much longer to reach the surface but that’s where you need it to avoid water hammer damage.
From what sketchy details I can see in that diagram, the downstream surge tank appears to be in about the right place but there are no details that I can find showing that the design dimensions are correct. The fact they made such a blunder with the upstream surge tank doesn’t bode well for the downstream surge tank intended design, does it?
I can’t find online the detailed design plans for these Snowy 2.0 major power waterway components so I don’t yet know most of the intended dimensions of the surge shafts and tanks to comment about this specifically.
Generally speaking, for open air surge shafts and tanks, shaft diameters below the elevation of the respective reservoir’s minimum operating level minus the frictional head loss (for the maximum flow rate to or from the pump-turbine through the tunnel from or to the reservoir) can match the respective tunnel’s diameter and above this surge shafts should open out into wide surge tanks where bigger is operationally better though more expensive to build. Surge tanks should crest at an elevation no lower (higher is fine) than the respective reservoir’s crest elevation plus a height equivalent to the greater value of the frictional head loss or as necessary to contain the surging volume. In case of spills over a surge tank’s crest, engineer a spillway.
Snowy 2.0’s final design plans should be available for public scrutiny and for that reason downloadable from this Snowy Hydro documents page but I haven’t found them there or anywhere as yet.
I haven’t seen enough of the details of the final design plans to give them my blessing, sorry. I have serious concerns about this reported water hammer problem and I am not content with the proposed positioning of the upstream surge shaft & tank.
I am an enthusiastic supporter of the Snowy 2.0 project but I am concerned with the reported water hammer problem with the proposed final design.
I really don’t want Snowy 2.0 to be cancelled – I am no vulture circling – but I would like to have the scheme well-designed so that it works well and it proves to be resilient for its 150 years design life.
Snowy Hydro needs to be transparent about Snowy 2.0’s final design so that any design errors can be identified and corrected before it is too late.
Come on Snowy Hydro, SHOW ME THE PLANS! 😡
UPDATE – Snowy 2.0 Headrace Surge Shaft & Tank Design
See also –
Snowy 2.0 Headrace Tunnel Rescue Plan
Snowy 2.1 – pumping up from Blowering Reservoir
Active feral horse shooters blackmail Snowy 2.0
Scottish Scientist 
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