Table 2.1 (continued) Indicative frequency and criteria Maintenance action (where required) Every 3 years Drain, clean out and check the condition of the tank walls and roof to ensure no holes have arisen due to tank deterioration Repair tank defects Check sediment levels in the tank Organise a suitable contractor to remove accumulated sediment if levels are threatening to block tank outlets or are affecting water quality Undertake a systematic review of operational control of risks to the system Identify the reason for any problems identified and take actions to prevent failures occurring in future After 10 years and then every 5 years Monitor soil copper and zinc levels Stop roofwater irrigation if levels exceed criteria After 20 years and then every 5 years Monitor the effectiveness of any irrigation equipment over 20 years old for clogging due to algal growth Clean or replace any clogged equipment Note: These recommendations do not supersede any relevant state or territory requirements. Maintenance should also include inspection and follow up on any complaints or concerns raised that could indicate problems with the system. Monitoring should be designed to identify any problems with the system’s operations (eg potentially system-related health problems where a reasonably static population is exposed, such as childcare facilities, and effects on plants watered by roofwater). However, it is not necessary to undertake routine monitoring of the quality of roofwater used for garden watering, toilet flushing and laundry use. 2.5 Nonresidential roofwater reuse checklist This checklist summarises the key health and environmental risk management actions for a nonresidential roofwater scheme where there is no intentional drinking or contact with roofwater. D Planning and other regulatory requirements are met. D The operating organisation is committed to the safe collection and use of roofwater, including ensuring appropriate operation and maintenance.
Table 3.5 Standard stormwater scheme monitoring Scheme type Frequency Monitoring Action All schemes Quarterly and in response to notifications Check condition of catchment, irrigation area and irrigated plants and grass Check irrigation areas for signs of erosion, underwatering, waterlogging or surface runoff Undertake corrective actions Modify irrigation practices Annually and in response to blockages Check lines for and leaks Clear blockages and flush/clean lines; repair leaks All schemes with tanks Annually and in response to notifications and new connections Triennially and following any incidents Annually and in response to notifications Triennially or as appropriate Check for by checking visible plumbing fittings, alternately turning off supplies Undertake a systematic review of operational control of risks to the system Check access covers to storage tanks are closed Check that screens on inlets, overflows and other openings do not have holes and are securely fastened Inspect tank water for mosquito larvae (inspect more frequently in subtropical and tropical northern Australia based on local requirements) Drain, clean and inspect storage tanks Shut down system immediately and rectify problems Determine the reason for any problems identified during inspections and take actions to prevent failures occurring in future Repair any defects Repair any defective screens Treat tanks containing larvae with kerosene or medical paraffin Repair any defects b
Table A3.6 (continued) Use Log reduction targetsa Indicative treatment processb Log reductions achievable by treatmenta On-site preventive measures Indicative exposure reduction (log reductions) Water quality criteria Option 1C: Municipal use, with drip irrigation V 1.3 P 0.8 B 1.3 No treatment 0 Drip irrigation of plants 4.0 Not applicable Option 2: Dual reticulation with indoor and outdoor use OR Irrigation of commercial food crops V 2.4 P 1.9 B 2.4 (if and disinfection 12.5 >>4.0 >>4.0 cross- required including ongoing education of householders and plumbers (for dual reticulation) Turbidity: <25 NTU (maximum), <10 NTU (95th percentile), <2 NTU (target) E. coli <1/100 mL NTU = nephelometric turbidity units; UV = ultraviolet. a Given as ‘V’, ‘P’or ‘B’, where V = virus, represented by adenovirus type 41 for UV, which is more resistant and better characterised than rotavirus; P = protozoa, represented by Cryptosporidium spp. oocysts; B = bacteria, represented by E. coli, which is more resistant and better characterised than Campylobacter. b Indicative UV doses given are based on US EPA (2006) and refer to validated doses taking into consideration RED bias and other factors. Appendix 3: Health risk assessment and management 67 ion
Note: Results are from one sample. Source: AWQC (2008b). Figure A3.2 Cryptosporidium dose–response curves for UV disinfection for three turbidities Note: Results are from one sample. Source: AWQC (2008b). Figure A3.3 E. coli dose–response curves for UV disinfection for three turbidities
Table A3.10 Tolerable pathogen levels and required reductions for different uses of roofwater Use Reference pathogen Tolerable concentrate- (infectious units per L) Required reduction (or safety margin) Equivalent of municipal, including open-space Campylobacter jejuni 0.76 Not required (–1.1 log10) irrigation, dust suppression (exposure = 50 mL/ person/year) Implications Treatment not requireda Equivalent of dual reticulation for indoor Campylobacter jejuni 0.057 17.2% 0.1 log10 and outdoor use (exposure = 670 mL/ person/year) Implications Treatment not requiredab Equivalent of commercial food crops Campylobacter jejuni 0.078 Not required (–0.1 log10) (exposure = 490 mL/ person/year) Implications Treatment not requireda Equivalent of non-food crops (eg trees, turf, Campylobacter jejuni 0.76 Not required (–1.1 log10) woodlots, flowers) (exposure = 50 mL/ person/ year) Implications Treatment not requireda Equivalent of firefighting (exposure = 1000 mL/ Campylobacter jejuni 0.38 45% 0.25 log10 person/year) Implications Treatment not requiredab a Treatment is not required if exposure controls can be maintained as recommended. b Even though the value is positive rather than negative, treatment is not required due to the very small log reduction predicted being outweighed by the conservatism in the estimates.
Table A4.2 Generic environmental risk assessment for municipal irrigation of roofwater Hazard Maximum risk — no preventive measure (ie uncontrolled) Critical control point or control point in environ- mental pathway Preventive measures Residual risk — with preventive measures Use or expos- ure entry Receiving environ- ment or receptor Environ -mental end point Effect Like- lihood Impact Level of riska Like- lihood Impact Level of risk Copper Irrigat- ion Plants Plants Toxicity Almost certain Minor Moderate Source water Roof condition management Unlikely Minor Low Almost certain Minor Moderate Irrigation Irrigation tools Unlikely Minor Low Almost certain Minor Moderate Irrigation Monitoring Unlikely Minor Low Soils Plants Toxicity Almost certain Minor Moderate Source water Roof condition management Unlikely Minor Low Almost certain Minor Moderate Irrigation Irrigation tools Unlikely Minor Low Almost certain Minor Moderate Irrigation Monitoring Unlikely Minor Low
The soil metal concentration trigger values in Tables A4.3 and A4.4 are the soil ecological investigation levels from NEPC (1999). These levels are lower, and hence more conservative, than the cumulative contaminant loading from ANZECC–ARMCANZ (2000a) when converted to milligrams per kilogram, based on an assumed soil accumulation zone depth of 75 mm and a soil bulk density of 1333 kg/m3 (EPA NSW 1997). All control points, preventive measures, target criteria, critical limits, critical control points, and their verification are site and scheme specific. Table A4.3 Copper: preventive measures for roofwater irrigation Control points Preventive measures Target criteria Verification Source water Irrigation or watering Roof condition management Avoid using from copper roofs. Irrigation tools Irrigation rates should be less than 300 mm/year. Limit irrigation using roofwater to 10 years unless monitoring shows soil copper levels are below target criteria. No copper roofing material. Median copper concentration in soil should be less than 100 mg/kg. Not applicable. Soil copper concentrations are below critical limit for plants likely to be irrigated by open-space irrigation.
Table A4.4 Zinc: preventive measures for roofwater irrigation Control points Preventive measures Target criteria Verification Source water Irrigation or watering Avoid irrigating using roofwater from roofs (eg galvanised iron) or painted roofs. Irrigation tools Irrigation rates should be less than approximately 300 mm/year. Limit irrigation using roofwater to 10 years unless monitoring shows soil zinc levels are below target criteria. No zinc-coated roofing material. Median zinc concentration in soil should be less than 200 mg/kg. Not applicable. Soil zinc concentrations are below critical limit for plant toxicity.
Table A4.5 Hydraulic load preventive measures Control points Target Verification Irrigation Irrigation tools When irrigating, apply appropriate volumes of water and use alternative irrigation methods (eg drippers) to restrict rates of water addition. Ensure irrigation scheduling methods follow best practice. Water applied must be carefully calculated to match current demand, according to standard protocols (Allen et al 1998, Christen et al 2006). Soils Site selection Select sites with sufficient drainage capacity. If there is a shallow A soil horizon above a layer of impermeable clay, this may lead to waterlogging. Verify watertable is >2 m from soil surface or the lateral hydraulic conductivity of the watertable will handle required leaching fractions and irrigation rates. Drainage Subsoil drainage can be installed to increase infiltration rate and remove excess water. Delivery of correct water volumes. Drainage capacity of specific site is appropriate. Groundwater below 2 m. Drainage >5 mm/hour. Soil water content remains less than field capacity, except where leaching is required. If leaching is required, ensure it is minimised. Appropriate volumes of water are applied for plants grown, weather conditions, soils and the leaching fraction required. Calculated amount of water needed is recorded, measured on application and documented. No symptoms of waterlogging in plants. Symptoms include yellowing or decay between the veins, leaf tissue becoming soft at the base or in the centre. Wilting may occur due to root decay, damaged roots appear blackened. Hydraulic conductivity of the soil profiles copes with the required leaching fraction and irrigation volume required for the plants to be grown (saturated hydraulic conductivity) at least >5 mm/hour). Groundwater remains below 2 m during irrigation and rain events. Soil water content less than field capacity; drainage at least >5 mm/hour. Ground- water Monitoring Ensure watertable remains >2 m from soil surface. Groundwater below 2 m. Verify watertable >2 m from surface. Note: All control points, preventive measures, target criteria, critical limits, critical control points, and their verification are P
Appendix 6 Health and environmental risk management for other applications A6.1 Potential uses of roofwater and stormwater As noted in Chapter 1, these guidelines have been prepared to support the most common forms of roofwater and stormwater reuse, particularly public, open-stage irrigation. Roofwater and stormwater can, however, be used for a range of other applications including: drinking — refer to – enHealth (2004) for domestic roofwater drinking – the Australian Drinking Water Guidelines (NHMRC–NRMMC 2004) for commercial or community rainwater drinking applications – the Australian Guidelines for Water Recycling: Augmentation of Drinking Water Supplies (NRMMC–EPHC–NHMRC 2008) for drinking stormwater managed aquifer recharge— refer to the Australian Guidelines for Water Recycling: Managed Aquifer Recharge (NRMMC–EPHC–NHMRC, 2009). Other potential uses (excluding drinking water), such as those noted in the Phase 1 guidelines (NRMMC–EPHC–NHMRC, 2006), are listed in Table A6.1.