Stormwater run off from one of Ballarat City Council’s housing estates, Lake Gardens, is now being used to water the Ballarat Botanical Gardens. The initiative has overcome the expensive and time consuming process of carting water to keep historic plantings alive.
Located approximately 100 kilometres northwest of Melbourne, Stage 4 water restrictions were imposed in Ballarat in 2006. This severely compromised Council’s ability to deliver an adequate irrigation program, sufficient to meet horticultural needs at the gardens.
As such, Council installed water tanks in the gardens, with a total capacity of 80,000 litres. The tanks were connected to the garden’s watering system and replenished almost daily by water carters at a significant ongoing cost to Council. This allowed a reduced watering regime to be delivered, ensuring that core plantings survived.
However, in spite of these supplementary measures, established plantings and older trees suffered as a result of prolonged dry conditions. Gardens staff estimate that 120,000 litres of water a day is needed to maintain historic trees and recently planted collections, as opposed to the 80,000 litres a day they were receiving since Stage 4 restrictions were introduced.
As part of ongoing efforts to ensure the sustainability of the gardens in the long term, Council undertook a detailed analysis of stormwater flows around Lake Wendouree, which borders the Lake Gardens estate and the Botanical Gardens. The analysis showed that the main stormwater outfall from Lake Gardens is delivered by a stormwater drain to the north of the Ballarat Botanical Gardens. To harness this stormwater, Council installed a diversion system redirecting flows to Swan Pool, an ornamental lake in the gardens.
Thirty millimetres of rain in the Lake Gardens stormwater catchment can fill Swan Pool to its three megalitre capacity, which is enough to irrigate the gardens for up to 25 days.
Council connected Swan Pool via a pump and pipeline to the existing water tanks at the Botanical Gardens. The fully automatic system means the 80,000 litres of water previously carted to the gardens can now be used on other Council assets. Most importantly, the significant plantings at the gardens can be properly irrigated into the future.
Council is also working with Central Highlands Water to pipe recycled wastewater to Swan Pool. This pool will then remain full year round, ensuring a constant water supply for irrigation of the Botanical Gardens.
The irrigation project will eventually extend to other areas of the City, including the Australian Ex Prisoner of War Memorial and the newly established Prince of Wales Park Croquet Club.
