~ r e f ereed pape r stormwater harvesting catchment management. The primary Gross Pollutant Trap (GPT) was installed in a prominent location where residents can observe functioning and downstream benefits. Interpretative signage was installed at key locations throughout the scheme. • System level - a treatment train approach incorporating a series of system components designed to remove pollutants in the stormwater. Table 1. Main Harvested stormwater quality targets. Total suspended solids Salinity pH Biochemical oxygen demand Total Phosphorus Total Nitrogen EColi • Operational level - operation of the system in a manner that optimises the quality of the stormwater. Iron • Finally, the advanced treatment system provided at the lcely Rd WTP, involving ozone and BAC. Oil and grease Community Consultation Community resistance to the concept of drinking stormwater was initially thought to be a significant challenge. However, through community education on the treatment processes and the necessity for securing the future of Orange's water supply, community acceptance was achieved relatively quickly and easily. Local and national media coverage, community information session, on-line surveys and explanatory signage at key locations were important factors in ensuring the concept of adding stormwater to the potable supply was widely accepted by residents. The predominant response was not one of concern about water quality but one of urging Council to get on with the work as soon as possible. Scheme Layout, Operation and Monitoring Major components of the harvesting scheme include: • Two large Gross Pollutant Traps (GPTs); • A harvesting weir (3ML) and Pump Station 1 with a capacity of 450Us; • A 200ML holding pond that is used to balance harvested stormwater flows with the treatment system; • Pump Station 2 with a capacity of 150Us to transfer water from the holding pond through the treatment system to the batch ponds; • A treatment shed; • Two 1 ?ML batch ponds; and • Pump Station 3 with a capacity of 150Us to transfer treated stormwater to Suma Park Dam. The treated stormwater is transferred through an 78 APRIL 2010 water < 50 mg/L < 20 NTU < 300 µS/cm 6 to 9 < 30 mg/L < 0.5 mgP/L < 5.0 mgN/L Turbidity < 10,000 CFU/lOOmL < 2.0 mg/L Lead Manganese Total Petroleum Hydrocarbons < 1.0 mg/L < 1.0 mg/L < 10 mg/L < 1 mg/L existing main towards Suma Park Dam with an extension allowing discharge to the dam . Flows in Blackmans Swamp Creek respond quickly to rainfall and when runoff from the city causes the flow to reach 1OOOUs, Pump Station 1 activates and draws water from the harvesting weir at a rate of 450Us. The operating rules require that a base flow immediately downstream in the creek must be maintained. Harvested stormwater is transferred to the 200M L holding pond where some settling takes place. Water is extracted from the holding pond by Pump Station 2 at a rate of 150Us, through the treatment shed. A flocculant (aluminium chlorohydrate) is added before being pumped into one of two 1?ML batch ponds. In Stage 1 of the project (Batch Mode) samples were taken from two depths in each batch pond for quality analysis. If sample quality met the target values (Table 1), water was then transferred to Suma Park Dam. The combined water is then treated at Councils advanced water treatment facility (ozone and biolog ically activated carbon filters) before being pumped into the city's potable supply system. Results Water Quantity The first transfer of 12 ML to Suma Park Dam was achieved on 21 April 2009. As at March 2010, 32 harvesting events have been undertaken in Batch Mode, yield ing 525 ML of water, some 15% of the total flow of the creek.and more than 13 % of the city's current demand. Co nti nuous Mode commissioning has now commenced. Water Quality In batch mode of operation, water was only t ransferred to Suma Park Dam once the water quality analysis passed all the target criteria that had been developed in consultation with Geolyse. Over 130 targets have been set for the water quality of t he batch ponds, the main ones being summarised in Table 1. Sources utilised in setting the targets included the Australian Drinking Water Guidelines (NHMRC & NRMMC, 2004), t he Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC & ARMCANZ, 2000), Australian Guidelines for Water Recycling (EPHC et al, 2008) and Australian Runoff Quality: a Guide to Water Sensitive Urban Design (Engineers Australia, 2006). Due to various test methods employed by laboratories, over 230 analytes are being reported. It is envisaged that at the end of the commissioning phase and full review of water quality results that some analytes will be removed from the standard analysis sweep (i. e. those that have not been detected) and only tested for periodically. Quality summary as at 20 January 2010 Pesticides and herbicides • From all samples from Blackmans Swamp Creek (BSC) and the batch ponds there has been no detection of: - Organochlorine pesticides (OCPs) - Organophosphorus pesticides (OPPs) Following successful operation for ten months, the system will move into Continuous Mode. This involves a continuous cycle of pumping harvested stormwater from the holding pond to Suma Park Dam via the batch ponds, with a turbidity probe providing a continuous indicator of water quality backed up by water samples being taken on average from every 8 ML of water. • In Batch Po nds t here has also been no detection of: - Glyphosate • Phenoxyacetic acid herbicides: concentrations with in the batch ponds d id not exceed the set target criteria. PCBs, hydrocarbons, Phenols, voes • From all samples from BSC and the batch ponds there has been no detection of: technical features