Salisbury, SA - getting stormwater harvesting right ...

Parafield Stormwater Harvesting Facility

The Parafield Stormwater Harvesting Facility originated from a discussion in 1999 between City executives and the management of G. H. Michell & Sons, Australia's largest wool processing company.

The company's processing involves the use of 1100 million litres per year of mains water to wash the wool, which in turn produces large quantities of effluent and sludge. The costs of fresh water and sewerage disposal were high enough to force the company to consider alternative, cheaper locations elsewhere, potentially resulting in the loss of around 700 local jobs.

The Parafield stormwater project involves diversion of stormwater via a weir in the main Parafield drain to a 50 million litres capacity capture basin. From there, it is pumped to a similar capacity holding basin, from where it gravitates to a two hectare cleansing reed bed.

Nutrient and pollutant loads are typically reduced by up to 90 per cent and the treated water salinity is less than 250 mg/L. The system is designed to hold stormwater for around 10 days to ensure optimal treatment efficiency.

The current supply capacity of the scheme is 1100 million litres per year. The second stage would add other catchments and boost the supply to 2100 million litres per year.

Continuity of supply is gained through the creation of large underground storage of treated stormwater. This is achieved by the development of an Aquifer Storage and Recovery (ASR) system. Two ASR bores (depth 180 metres, T2 Aquifer) have been installed allowing supply when the system has no flow. The recharge water quality has to meet the Environment Protection Authority (EPA) requirements.

Through the project, G.H. Michell & Sons will receive water with a salinity (TDS) of 250mg/L, which is significantly lower than the salinity of water from the River Murray (> 400 mg/L). The ASR project will foster the growth of new and established industries, especially those with high water quality requirements. Prospective employment opportunities in the region will be subsequently increased.

See - Salisbury stormwater harvesting.