I set out to find out exactly where the 5.1 km long penstock pipeline for BC Hydro’s Puntledge Generation Station transitions from the welded steel construction that most people see, to the wood stave construction that is a bit off the beaten path.
The Puntledge diversion dam
While I could start this at the Puntledge Generation Station or the diversion dam, the plan of the diversion dam indicates that there was wood stave penstock pipe, so this was a logical starting point.
The Diversion Dam is a 30.5 long concrete buttressed structure with a crest elevation of 133.2 m, connected to the 20-ha Puntledge Head Pond. Outflow from the Head Pond to the penstock is controlled by two 5.23 m wide x 4.14 m high sluice gates. The sill elevation of the sluice gates is 125.12 m. The overflow spillway from the Head Pond is a three-section compound weir at 130.2 m (76.2 m long), 130.29 m (9.1 m long) and 130.38 m (30.5 m long) elevations. The normal operating water level of the Head Pond varies between 129.9 m and 130.2 m.
BC Hydro
Looking toward the diversion dam
3.66 m diameter wood stave penstock pipe is used for the higher elevation, lower pressure section of the pipeline – this first approximately 1.3 km section of the penstock runs from the Puntledge diversion dam 3.7 km downstream of the Comox Lake impoundment dam.
Looking toward the diversion dam – the pipe line follows the terrain…
3.0 m diameter welded steel pipe is used for the approximately 3.8 km section of higher pressure, lower elevation section of the pipeline heading down to the Puntledge Generation Station. This is the same arrangement that you’ll see used at the John Hart Generation Station near Campbell River.
At some point, the pressure within the penstock pipeline increases to the point where the transition from wood stave to welded steel penstock pipe is made – but where?
The transition point
And here’s where the transition point is
[fbalbum url=”https://www.facebook.com/media/set/?set=a.269225416534510.1073742048.123247217798998&type=3″ size=”187″]
And now you know…