Case study: Royal Society for Prevention of Cruelty to Animals (RSPCA)
This project was small and had a number of fascinating aspects that added great interest for the team as designers. As part of an expansion and refurbishment of the facilities at the Royal Society for Prevention of Cruelty to Animals (RSPCA) Burwood site in Melbourne, Australia, and due to a long-running drought through Southeastern Australia, they decided to implement some water-saving strategies (see Figure 1).
As part of statewide water restrictions, irrigation of landscape areas was restricted, so the initial brief from the client was to provide a source of water for irrigation of a landscaped area. Their initial thoughts were that the irrigation would come from rainwater collected onsite. However, after looking at the daily rainfall figures and performing water balance for their complete operations, it was clear that while the rainwater-collection tanks may be overflowing in winter, this approach could not provide the irrigation water they needed during the summer months.
It also became apparent through metering that they were using large amounts of water for a daily washdown of the kennels and other facilities within the site. As part of a broader overall water sustainability plan that included installation of low-flow fixtures and submetering of major water uses, a strategy was developed to reduce the overall water use and make double use of the landscaped area: to provide both a lush green landscape area and treat the washdown water to allow reuse for kennel washdown the following day.
This was achieved through the installation of low-flow high-pressure sprayer nozzles for the kennel washdown to reduce water use and the use of a multistage passive vertical flow reed bed system integrated into the landscape for treatment of the washdown water prior to reuse. Because the site is on a slope, pumping is minimized by moving the water through the system and between stages using dosing siphons. Buildup of total dissolved salt caused by the constant recirculation and reuse of water is managed by bleeding a portion of the treated water from the system to the sewer and replenishing with rainwater supplies.
The water cleaned through the reed bed system is disinfected using ultraviolet (UV) and chlorination to remove pathogens prior to reuse. Excess rainwater is used in the building for toilet flushing. This project illustrates an integrated approach to water use across the site. The scheme was completed in 2013 and saves approximately 1,600 gpd or 584,000 gallons/year in water use, not including the irrigation requirements avoided by installation of the green landscaped reed bed areas and the low-flow fixtures.
Peter Harbour is a senior scientist at CJ Arms and Associates.
Robyn Overall is water sustainability scientist at CJ Arms and Associates.