The Hill with the Hole

About trip

Minimum Time: 1hr 45mins Ascent: 1,200ft Difficulty Level: 3 - Hard Paths: Steep rugged paths, 2 ladder stiles Landscape: Wooded slopes and high corrie Dog Friendliness: Good, but high and steep ladder stiles to negotiate Parking: Two pull-ins on north side of A85, below railway station. Also lay-by 0.5 miles (800m) west. Not visitor centre car park Public Toilets: Cruachan Visitor Centre Description: The Cruachan Reservoir collects rainfall from a fairly small catchment, 9 square miles (23sq km) bounded by the rocky ridge of Ben Cruachan. Even with Cruachan’s 116in (2,945mm) of rain a year, only 4 megawatts of power are generated, not enough to supply Oban, to the west. The Big Battery But Cruachan is more than just a rather small power station. It’s a rechargeable storage system for electrical energy, a very big electric battery. The demand for electric power varies from day to day, and even from minute to minute. There’s the surge at the advertising break during your favourite soap, as a million kettles get switched on at once. Coal and oil power stations can be stoked up or cooled off, but only quite gradually. Nuclear stations run at the same rate day and night. And the greenest energy sources, wind and wave generators, give power according to the weather. So there has to be a way of taking electricity out of the National Grid when there’s too much, and putting it back when it’s most needed. Cruachan Power. Fortunately, an electric generator running backwards becomes a motor, and a turbine turns into a pump. At ‘white-meter’ (off-peak) times of day, water is pumped from Loch Awe up to Cruachan Reservoir, 1,000ft (305m) above. And at 7:15 on a weekday evening, it flows back down again. The stored energy in the battery of your car is sufficient to keep it running for about half a minute, but that’s enough to start it in the morning and run the CD player when the engine’s off. Full to the brim, Cruachan Reservoir, with the capacity of about half a billion car batteries, in theory holds enough potential energy to supply the UK’s peak demand for 10 minutes. In fact the water can’t be drawn down that fast, but at full flow Cruachan can supply 400 megawatts, enough for most of Glasgow. Time your arrival for 7:15pm, and you could see the reservoir sinking at an inch (2.5cm) per minute. The same amount of water will be flowing out into Loch Awe, just beside the visitor centre. The whole process - pumping up and then retrieving the potential energy - is not much more than 50 per cent efficient. The waste heat ends up in Loch Awe, where it benefits the fish farm opposite the visitor centre. The Secret Source The Cruachan powerhouse makes a fairly small impact on the outer world. Around 12 miles (19.3km) of pipes bring water into the reservoir, and the outgoing or incoming electricity loops across the hill on high pylons. The 1,030ft (314m) dam is only visible once you reach the corrie; the power station itself is actually buried deep in the heart of the mountain. While you're there: From the visitor centre, you can pass by underground tunnels to the vast chamber of the Machine Hall, which houses the power station’s four turbines. At this point you’re about 0.75 mile (1.2km) into the mountain, and 1,000ft (305m) below the reservoir. Waste heat from the turbines, as well as plenty of electricity for lighting, means that subtropical plants are able to thrive in this technological underworld. What to look out for: From the mountain slope you look down the length of Loch Awe to its distant outflow - except that you don’t. Loch Awe is a reversed lake. Since the ice age, the original outflow at the southern end has silted up and raised the water level to the point where a new outlet formed at the north-western corner. As the descent from here to the sea is fairly steep, a small gorge has formed. This has lowered the lake level and eliminated the original outflow altogether. Where to eat and drink: There’s a café at the Cruachan Visitor Centre during its opening hours. Oban has a wide selection of cafés, restaurants and pubs looking out over the harbour. The Falls of Lora Hotel, at Connel Bridge, has a bistro offering everything from fish and chips to venison and oysters (no dogs allowed). Watch out for Loch Etive’s seals and otters opposite to the hotel. Directions: Two paths run up on either side of the Falls of Cruachan. Both are initially rough and steep through woodland. The western one starts at a tarred lane opposite the entrance to the power station proper (not the visitor centre, slightly further to the west). This diminishes to a track, which becomes rough and crosses the railway as a level crossing. A path continues uphill in steep zigzags through birch, rowan and oak. There are various points to stop and admire Loch Awe, which disappears glittering in the distance. White speckled stones in the path are Cruachan granite. The path continues on steeply to the top of the wood. 2 Here a high ladder stile crosses a deer fence. With the stream on your right, continue uphill on the small path to a track below the Cruachan dam. Turn left, up to the base of the dam, which measures 1,030ft (314m) wide and 150ft (46m) high. Because it’s tucked back into the corrie, it can’t be seen from below, but it is clearly visible from the top of Dun na Cuaiche (see Walk 3), 12 miles (19.3km) away. The hollows between the 13 huge buttresses send back a fine echo. Steps on the left lead up below the base of the dam, then iron steps take you on to the dam’s top. 3 From here you can look across the reservoir and up to a skyline that’s slightly jagged at the back left corner, where Ben Cruachan’s ridge sharpens to a rocky edge. In the other direction, your tough ascent is rewarded by a long view across Lorn. Turn right to the dam end, where a track leads down right to a junction, then right for 50yds (46m). 4 At this point you could stay on the track to cross the concrete bridge just ahead, leading to the top of the path used for coming up. Otherwise there is a clear path as you go down to the left of the stream, to reach a high, steep ladder stile. (There’s a useful dog flap in the deer fence alongside.) Below this there is a clear path that descends grassy slopes and gives a good view of some of the Falls of Cruachan. Inside the wood, the path becomes steep and rough for the rest of the way down. Just above the railway, it turns left, then passes under the line by a low tunnel beside Falls of Cruachan Station, to the A85.