Part 9: The "U" Tube Nears Completion

A skateboarder's heaven plays a vital role at Hume Dam.

Often idle for years on end but when required, this monolith is designed to withstand and blunt the enormous forces unleashed from millions of litres of water cascading into the trough from the crest of the spillway 35m above. The wall then ushers this raging torrent through the stilling pool to begin its long journey to the sea.

This spectacle, combined with its thunderous roar and billowing spray, attracts sightseers from far and wide.

The downside is the perennial argument around pondage for irrigation versus airspace for flood mitigation. Far more frequently, however, is the acrimonious issue of water allocations between environmental and irrigation interests. In our land of extremes, with droughts and flooding rains, we are not likely to see resolutions with which everyone will agree.

The Border Mail of October 27, 2000, listed flood peaks recorded on the Murray at Albury. The top six were - October 28, 1870, 5.89m; October 22, 1917, 5.83m; October 8, 1867, 5.79m; October 27, 1975, 5.69m; October 19, 1974, 5.55m; October 10, 1992, 5.40m. More recently, on October 6, 2016, it reached 5.36m. It could be argued that snow melt in October may be a factor.

The dissipator wall is 220m long, 7.5m high, its crest is 4.18m wide while its base extends for 12m downstream. Unlike the stilling pool beside it, which has an upturned ramp at its downstream extremity, the base of the dissipator wall has a five metre downturn to bedrock for its downstream foundations.

The photo shows a workman in a precarious position on a concrete chute, directing concrete into this downstream section. OH&S issues did not complicate working life in the 1930s.

The curved formwork is not in use but shows how the wall was built. On the spillway, a small section of formwork is in place.

Bronze bolts were inserted into the wet concrete.

When set, this allowed the boxing to be bolted to the wall when it was lifted for the next pour.

The spillway's main slope is 64 degrees.

Post World War 1, cement was often in short supply. On occasions, usage on the NSW side exceeded 3000 bags per day. A total 25,000 bags were kept in reserve on site, with that many again at the North Street siding in Albury.