Table 3.8 Treatment processes and on-site controls for designated uses of recycled water from treated sewage Log Indicative treatment process Log On-site preventive measures Expo- Water quality objectivesc reduction reductions sure targets (V, P, B)a achievable by reduct- ionb treatment (V, P, B) Use — Dual reticulation, toilet flushing, washing machines, garden use 6.5 5.0 5.0 treatment required, such as: • secondary, coagulation, filtration and disinfection • secondary, membrane filtration, UV light 6.5 5.0 5.0 cross-connection controls required including ongoing education of householders and plumbers • To be determined on basis depending on technologies • Could include turbidity criteria for filtration, disinfectant Ct or dose (UV) • E. coli <1 per 100 mL Use — Dual reticulation — outdoor use only or indoor use only 6.0 4.5 5.0 treatment required; for example: • secondary, coagulation, filtration and disinfection • secondary, membrane filtration, UV light 6.0 4.5 5.0 cross-connection controls required, including ongoing education of householders and plumbers • To be determined on basis depending on technologies • Could include turbidity criteria for filtration, disinfectant Ct or dose (UV) • E. coli <1 per 100 mL Municipal use — open spaces, sports grounds, golf courses, dust suppression, etc or unrestricted access and application 5.0 3.5 4.0 for • secondary, coagulation, filtration and disinfection • secondary, membrane filtration, UV light 5.0 3.5 4.0 • To be determined on basis depending on technologies • Could include turbidity criteria for filtration, disinfectant Ct or dose (UV) • E. coli <1 per 100 mL N s p van van
Table 3.8 (continued) Log Indicative treatment process Log On-site preventive measures Expo- Water quality objectivesc reduction reductions sure targets (V, P, B)a achievable by reduct- ionb treatment (V, P, B) Municipal use, with restricted access and application • Secondary treatment with disinfection 2.0–3.0 1.0 >6.0 Restrict public access during irrigation and one of the following: • no access after until dry (1– 4 • minimum 25–30 m buffer to nearest point of public access • spray drift control; for example, through low-throw sprinklers (180° inward throw), vegetation screening, or anemometer switching 2.0 1.0 1.0 1.0 • <20 mg/Ld • SS <30 mg/ Ld • Disinfectant residual (eg minimum chlorine residual) or UV dosee • E. coli <100 cfu/100 mL Municipal use, with enhanced restrictions on access and application • Secondary treatment with >25 days lagoon detention or primary 1.0–3.0 1.0–3.0 Restrict public access during irrigation and combinations of: 2.0 • mg/Ld • SS <30 mg/ Ld treatment with >50 days lagoon detention 3.0–4.0 • no access after irrigation, until dry (1– 4 hours) 1.0 • E. coli <1000 cfu/100 mL (disinfection may be required to • Secondary treatment 0.5–2.0 0.5–1.0 • minimum 25–30 m buffer to nearest point of public access 1.0 this concentration) 1.0–3.0 • spray drift control, eg through low throw sprinklers (180° inward throw), vegetation screening, or anemometer switching 1.0 B 0 <2 D O
Table 3.8 (continued) Log reduction targets Indicative treatment process Log reductions achievable On-site preventive measures Expo- sure reduct- Water quality objectivesc (V, P, B)a by ionb treatment (V, P, B) Commercial food crops 6.0 Secondary treatment or primary 0.5–1.0 Consumers • BOD <20 mg/Ld 5.0 treatment with lagoon detention 0.5–2.0 • Crops with no ground contact and heavily 5.0–6.0 • SS <30 mg/ Ld 5.0 1.0–3.0 processed (eg grapes for wine production, cereals) • E. coli <1000 cfu/100 mL • Crops cooked/processed before 5.0– consumption (eg potatoes, beetroot) 6.0 • no harvest of wet or dropped produce consumption (eg citrus, nuts) – no spray irrigation • Crops with no ground contact and skin removed before • Raised crops (eg apples, apricots, grapes) – drip irrigation and no harvest of wet, dropped produce • Pathogen reduction between harvesting and sale Public in vicinity of irrigation areae • No access and drip irrigation • No access during irrigation and, if spray irrigation, minimum 25–30 m buffer distance between irrigation area and nearest public access point, and spray drift control (eg through part circle sprinklers with 180° inward throw, vegetation screening, or anemometer switching) 6.0 5.0 0.5/day V, B 6.0 5.0 or • Extended buffer distances to >50 m
Cattle up to 12 months of age should be excluded from areas irrigated with recycled water that has been derived from sources containing livestock waste, unless there is sufficient data to indicate the risks for a specific case can be managed. 3.6.4 Contamination of milk via recycled water use in dairy operations While not a risk to livestock health, the use of recycled water in dairy operations can potentially contaminate milk and pose a risk to human health. Pasteurisation of milk will effectively kill bacterial pathogens, but may be inadequate for inactivating the viral and protozoan pathogens present in human faeces. Therefore, if recycled water is derived from sewage or source water contaminated with human faeces, lactating dairy cattle should be excluded from areas irrigated with recycled water until the pasture is dry; also, recycled water should not be used for wash down of milking machinery. Table 3.9 Treatment processes and additional controls for use of recycled water in association with livestock (excluding pigs) Use Indicative treatment processes On-site preventive measures Water quality objectives Livestock drinking water Dairy shed wash down • Secondary treatment with helminth reduction (>25 days of lagoon detention or an equivalent filtration process) and or • Primary treatment with >50 days of lagoon detention and • Secondary treatment with helminth reduction (>25 days of lagoon detention or an equivalent filtration process) and disinfection or • Primary treatment with >50 days of lagoon detention and disinfection • Recycled water not to be used for consumption by cattle under 12 months of age if the source of water contains animal (eg abattoir or saleyard) waste • Recycled water not to be used for wash down of milking machinery (unless specifically considered in human health risk assessment) • soluble BOD5 <20 mg/L • SS <30 mg/L • Disinfectant residual (eg minimum chlorine residual) or UV dosea • E. coli <100 per 100mL • soluble BOD5 <20 mg/L • SS <30 mg/L • Disinfectant residual (eg minimum chlorine residual) or UV dosea • E. coli <100 per 100 mL
Table 3.9 (continued) Use Indicative treatment processes On-site preventive measures Water quality objectives Pa sture or fodder crop irrigation (including hay, silage and commercial fodder production). Limited withholding period Pasture or fodder crop irrigation (including hay, silage and commercial fodder production). With withholding period. • Secondary treatment with helminth reduction (>25 days of lagoon detention or an equivalent filtration process) and disinfection or • Primary treatment with >50 days of lagoon detention and disinfection • Secondary treatment with helminth reduction (>25 days of lagoon detention or an equivalent filtration process) or • Primary treatment with >50 days of lagoon detention • Exclude lactating dairy cattle from pasture for four hours or until pasture is dry. • Fodder dried or ensiled (not for human consumption) Public in vicinity of site • No public access during irrigation • 25–30 m buffer distance to nearest public access point • Spray drift control, eg through low-throw sprinklers, microsprinklers, drippers, part circle sprinklers (180º inward throw), vegetation screening, or anemometer switching • Exclude grazing animals for 5 days after irrigation. • Fodder dried or ensiled (not for human consumption) Public in vicinity of site • No public access during irrigation • 25–30 m buffer distance to nearest public access point • Spray drift control, eg through low-throw sprinklers, microsprinklers, drippers, part circle sprinklers (180º inward throw), vegetation screening, or anemometer switching • soluble BOD5 <20 mg/L • SS <30 mg/L • Disinfectant residual (eg minimum chlorine residual) or UV dosea • E. coli <100 per 100 mL • soluble BOD5 <20 mg/L • SS <30 mg/L • E. coli <1000 per 100 mL BOD5 = biochemical oxygen demand over 5 days; SS =suspended solid; UV = ultraviolet a Aim is to demonstrate reliability of disinfection and ability to consistently achieve microbial quality
At this stage, a watching brief should be included in reviews of the risk assessment completed for recycling water. These national guidelines should also be updated or amended as ongoing research in Australia and elsewhere leads to a better understanding of the impacts of EDCs. More information on the current state of our knowledge of EDCs can be found on the websites of the WHO7 and the Water Environment Research Foundation.8 Estimate likelihood of hazardous event occurring Table 2.5 in Chapter 2 describes qualitative measures of likelihood. This step involves estimating the likelihood that an environmental endpoint will be exposed to the hazard in sufficient concentrations to cause a detrimental effect; a step that requires adequate information and suitable expertise. The descriptors and definitions outlined in Table 2.5 (Chapter 2) are then used to rate the likelihood of an event occurring. Likelihood of exposure to the environmental endpoint can often be determined by previous experience documented in reports (eg pipe bursts per year, tank leakage in other systems, cross- connections in other reuse schemes) or from professional opinion. For example, qualitatively, the likelihood of watering a lawn with recycled water is ‘almost certain’ (E in Table 2.5). To assess the likelihood of a main pipe bursting, it is necessary to check the age of the pipe and what it is made from, and compare that information with major pipe bursts identified from records kept within the relevant water authority. If the age and construction of the pipe are similar to those involved in major bursts, then the assessment may be that the likelihood is ‘possible’ (C in Table 2.5). To assess the likelihood that a selected environmental endpoint will be exposed to concentrations sufficient to cause a detrimental effect, the concentration or total load of the hazard will need to be calculated and compared with known guideline values (these guideline values will be used to set the target criteria or critical limits discussed in Section 2.3.2). Estimate consequences of hazardous event occurring Table 2.6 in Chapter 2 describes qualitative measures of consequences or impact. This section describes how to determine the consequences (or impact) of exposure to a hazard by considering: • the size and nature of the environmental population exposed to the hazard (ie specific endpoints) • the route, amount and duration of exposure. The impact should be put into an environmental context by using Table 4.4 (below) to help determine, qualitatively, what the impact is. 7 See 8 See
Table 4.5 Standard risk assessment sheet for identifying exposure pathways and impact of a particular hazard Hazard, exposure pathway, endpoint and effect Potential hazard Use or exposure pathway entry point Receiving environment or receptor Environmental endpoint Most sensitive specific endpoint Effect or impact on the environmental endpoint Boron Irrigation Air Biota — aquatic Biota — terrestrial Infrastructure Plants Soils Water — ground Water — surface Infrastructure Biota — aquatic Biota — terrestrial Infrastructure Plants Soils Water — ground Water — surface Plants Biota — aquatic Biota — terrestrial Infrastructure Plants Soils Water — ground Water — surface Soils Biota — aquatic Biota — terrestrial Infrastructure Plants Soils Water — ground Water — surface Water bodies Biota — aquatic Biota — terrestrial Infrastructure Plants Soils Water — ground Water — surface
Table 4.7 Example of an environmental risk assessment for sodium Hazard Maximum risk (ie no preventive measures, uncontrolled) Residual risk (ie with preventive measures) Use or Receiving Environ- Critical CP or CP exposure environment entry or receptor mental endpoint Effect Likelihood Impact Maximum in environmental riska pathway Preventive measure/s Likeli- hood Impact Resid- ual risk Salinity Cross- connect- Air Plants Plants None Toxicity Rare Minor Low – ion Soils Plants Salinity Unlikely Minor Low – Irrigation Air None – Infrastructure Infrastructure Salinity Possible Minor Moderate Soils Site selection Unlikely Minor Low Plants Plants Salinity Unlikely Minor Low – Soils Salinity Unlikely Minor Low – Sodicity Possible Moderate High Soils Soil ameliorant Unlikely Minor Low Possible Moderate High Shandy — saline Distribution system water Unlikely Minor Low Possible Moderate High Treatment process Water treatment Unlikely Minor Low Water — ground Salinity Possible Moderate High Irrigation Irrigation tools Possible Moderate High Possible Moderate High Soils Site selection Possible Moderate High Water — surface Salinity Unlikely Moderate Moderate Irrigation Irrigation tools Rare Moderate Low Unlikely Moderate Moderate Soils Site selection Rare Moderate Low Storage system Infrastructure None – Plants None – Soils None – Water body Water — Salinity ground Unlikely Moderate Moderate Buffer Storage system distances/strips Unlikely Moderate Moderate Decrease Treatment process concentration Unlikely Moderate Moderate Soils Site selection Water — surface Salinity Unlikely Minor Low Water body Water — Salinity ground Possible Moderate High Storage and distribution system Design Unlikely Minor Low Possible Moderate High Groundwater Monitoring Unlikely Minor Low Possible Moderate High Storage and distribution system Monitoring Washing Air None – Infrastructure Salinity Possible Minor Moderate Infrastructure Monitoring Rare Minor Low Water body Water — surface Salinity Unlikely Minor Low – Plants Plants Toxicity Rare Minor Low – Soils Plants Salinity Unlikely Minor Low – CP= control point Highlighting indicates a high or moderate maximum risk
Figure 4.5 How preventive measures and critical control points relate to target criteria and critical limits Preventive measures Hazard controlled by criteria and critical limit Exclusion barrier (prevents entry or removes hazard ) barrier (controls exposure) Within target criteria Monitoring program Deviation from target criteria Critical limit exceeded Critical Control Point health or environmental risk Losing control Take corrective action immediately Within target criteria Take corrective action Critical limit exceeded or environment regulator? Box 4.2 completes the example shown above in Box 4.1 for the four different plant species chosen as specific endpoints in the case of recycled water being used to irrigate an oval and nearby municipal gardens containing various native plant species. Box 4.2 Example of determination of target criteria The endpoint that is most sensitive to the hazard being assessed will often define the critical limits n n I r U C s s u t t t r
5.3.2 Operational monitoring for health risks Unacceptable risks from microbial infections can arise from even very brief, single exposures. Therefore, there is no room for even momentary failures in the barriers that protect users of recycled water from agents of disease. Fortunately, enough is known about most of the treatment processes and some of the usage control processes to ensure that operational monitoring can detect problems before excessive exposure has taken place. For example, this can mean online monitoring of processes such as filtration and disinfection. However, in lagoon systems, days to weeks may pass before water that has been tested will reach users, providing a window for less frequent monitoring and the use of microbial testing as part of operational monitoring. Table 5.4 gives further examples of operational monitoring and supporting programs. Table 5.4 Examples of operational monitoring and supporting programs for health risks Process step to be monitored Operational monitoring Supporting programs Media filtration plant • Turbidity downstream of system • Head loss across system • pH and temperature Primary settling system • Flow rate through the system • Solids depth Secondary treatment system • Flow rate through the system • Sludge blanket depth Lagoon • Flow rate through the system • Toxic blue-green algal levels and toxin concentrations • Microbial indicator concentrations Membrane plant • Turbidity downstream of system • Head loss across system • Particle counts on outlet Ultraviolet (UV) plant • Turbidity upstream • UV transmissivity • UV intensity and/or calculated dose • Flow rate • Ballast functionality • Lamp power • Lamp status • Cleaning frequency Chlorination plant • Turbidity upstream • Free chlorine, temperature and pH at downstream monitoring point • Flow rate to enable calculation of Ct Over-irrigation control • Soil moisture content • Irrigation time Accidental ingestion control • Timing of irrigation • Direction of sprinkler throw before application • Wind direction before application • Presence, currency and comprehension of user agreements • Presence, integrity and clarity of fittings, signage and other end-user controls • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program • Instrument calibration • Asset maintenance program
Table A1.1 (continued) Framework element and components Element 4: Operational procedures and process control Activity Components: Operational procedures Human health In relation to human health: • operational procedures were identified for all processes and activities associated with the system • documented procedures must be available to all operations personnel and available for inspection at any time. Environmental performance In relation to the environment, irrigation procedures were established to minimise salinity impacts, maintain nutritional levels, and minimise leaching and impacts on groundwater quality and quantity (all users of recycled water are trained in best management practices for irrigation). Operational monitoring Human health Monitoring requirements in relation to human health include: • standard wastewater plant requirements, such as biochemical oxygen demand (BOD), suspended solids, etc • Cryptosporidium inputs into the storage lagoons • flow rates (lagoon detention) — critical limit set • turbidity of filtered water (continuous) — critical limit set • disinfection (continuous) — critical limit set • on-site auditing of controls (signage, backflow prevention, etc). Environmental performance Monitoring requirements in relation to the environment include: • recycled water electrical conductivity (continuous) — critical limit set • pressure sensors in the reticulation system to identify pipe bursts and automatic cessation of supply if detected • visual inspection to ensure that best management practice for irrigation is followed and leakage from the irrigation and reticulation system is minimised • moisture sensors or other monitoring tools are used to maximise irrigation efficiency • irrigation monitoring is used to minimise runoff.
Table A1.1 (continued) Framework element and components Corrective action Human health Activity Equipment capability and maintenance In relation to human health, corrective actions include the following: • noncompliance with critical limits results in flow to the irrigation system being stopped automatically until remedial action is implemented; that is, flow is stopped if: – flow rates stop minimum lagoon-detention times being met – maximum turbidity (10 nephelometric turbidity units, NTU) is exceeded for more than 60 minutes – disinfection fails • users of recycled water who fail to apply on-site restrictions can be disconnected • noncompliance with other limits can result in corrective action being taken while the system remains operational • if Cryptosporidium numbers in the influent to the lagoons exceed 50/L, increased monitoring is activated at the DAFF plant and operators are notified. Environmental performance In relation to the environment, corrective actions include the following: • if the target value of 1450 mg/L TDS is exceeded, the continuous monitoring of EC of recycled water entering the reticulation system is reviewed and intensified; any corrective actions possible are taken to ensure the sewage systems and treatment plant has not malfunctioned • if the critical limit (1500 mg/L TDS) of the treated water is exceeded, then the treated water is ‘shandied’ with drinking water. Human health In relation to human health: • online measuring devices include 24-hour monitored alarm systems for key devices including filtration and disinfection; backup power is available • the filtration plant incorporates variable dosing and variable control of flow rates. Environmental performance In relation to the environment: • on-site moisture sensors or other monitoring tools are used to maximise irrigation efficiency • EC is also monitored continuously as a measure of TDS and salinity entering the system. Materials and chemicals • Quality assurance for materials and chemicals is applied to ensure that they do not introduce contaminants into the recycled water system.
Table A1.2 Framework elements applied to the use of recycled water through a dual- reticulation system Framework element and components Activity Element 1: Commitment to responsible use and management of recycled water quality Components: Responsible use of recycled water Recycled water policy Regulatory and formal requirements Engaging stakeholders • Development of the scheme involved collaboration between the water utility, the state department responsible for human health (eg Health Department — HD), the state department responsible for the environment (eg Environmental Protection Authority — EPA), the local council and the developers. • Regulatory requirements identified included the – Public Health Act – Environment Protection Act – Water and Sewerage Acts • Other stakeholders were – local community – plumbers and builders – general public. Element 2: Assessment of the recycled water system Components: Identify intended uses and source of recycled water • Intended uses included – toilet flushing – residential garden uses, car washing, etc – spray irrigation of parks and reserves (local council) • Source of water is a large metropolitan sewage treatment plant. Recycled water systems analysis • A catchment survey was undertaken to identify industries attached to the collection system. • The scheme included enhanced secondary treatment (with nutrient reduction), coagulation, dual-media filtration and chlorination. • Recycled water is distributed through a separate reticulation system, incorporating a 5 ML balancing storage before it reaches consumers. The system was installed in accord with WSAA Sewerage Code Version 2.1 (WSAA 2002a). Assessment of water quality data • The treatment plant includes a marine discharge and results from chemical testing undertaken over a 10-year period, in accord with EPA licence conditions were available for assessment.
Table A1.2 (continued) Framework element and components Activity Materials and chemicals • Quality assurance for materials and chemicals applied in the same manner as for water treatment facilities. Materials and chemicals selected to ensure that they do not introduce contaminants into the recycled water system. Element 5: Verification of recycled water quality Components: Recycled water quality monitoring (specifically designed for individual systems, taking into account source of water, end uses and receiving environments) Application and discharge site monitoring Satisfaction of users of recycled water Parameters monitored in relation to human health include: • adenovirus, Cryptosporidium, Escherichia coli • pH, heavy metals • disinfection byproducts, halogenated and non-halogenated organics, benzo(a)pyrene, herbicides and pesticides, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and volatile chlorinated hydrocarbons (VCH). Environmental performance Parameters monitored in relation to the enviroment include: SAR, chloride, chlorine disinfection residuals, nitrate and total nitrogen, available and total phosphorus. Environmental performance In relation to the environment, monitoring includes the following: • soils (eg SAR, nutrients, pH, conductivity) • groundwater (eg water levels, conductivity, nutrients). • Householder satisfaction is monitored by the operator of the recycled water distribution system. Complaints are investigated, particularly when clusters of complaints are received. Short-term evaluation of results • Results are provided routinely to EPA and HD. Exceedences of set guideline values are reported immediately in accord with an agreed incident protocol. Corrective responses Human health • Corrective responses depend on the exceedence. As a minimum, it involves investigation of plant performance records to confirm normal operation and additional testing to both confirm the exceedence and to identify the source. Environmental performance • Responses are specific to the impact, with a focus on identifying the cause and implementing preventive measures as required. Element 6: Management of incidents and emergencies Components: Communication Incident and emergency response protocols • An incident notification and communication protocol incorporates: – emergency contact lists – criteria for defining incidents – notification requirements, including timeframes – media and general communication protocols. Element 7: Employee awareness and training Components: Employee awareness and involvement • Regulatory approval includes the requirement that the plant is operated by appropriately trained and skilled personnel. Employee training u
Table A1.3 (continued) Framework element and components Activity Element 7: Operator, contractor and end user awareness and training Components: Operator, contractor and end user awareness and involvement Operator, contractor and end user training • Operator of treatment plant to be sufficiently skilled to run the plant and investigate any faults. • Operator to be aware of approval conditions and instructed on occupational health and safety requirements. • Irrigation personal are trained in requirements for irrigation with recycled water. Element 8: Community involvement and awareness Components: Community consultation • Council consulted with users of the golf course and advised local residents of the proposal before proceeding. communication and education Element 9: Validation, research and development Components: Validation of processes Design of equipment Investigative studies and research monitoring • None. Element 10: Documentation and reporting Components: Management of documentation and records • All operating procedures require documentation. All results to be recorded and stored. • Results to be reported on an annual basis to HD and EPA. Reporting Element 11: Evaluation and audit Components: Long-term evaluation of results Audit of recycled water quality management • Annual report on compliance with approval conditions, including test results, audited by HD and EPA. • Results from environmental performance monitoring assessed for changes over 5-year intervals. Element 12: Review and continual improvement Components: Review by senior managers • Operation of treatment plant and health of irrigated area reviewed by council. BOD = biochemical oxygen demand; EC = electrical conductivity; EPA = environmental protection agency; ESP = exchangeable sodium percentage; HD = health department; SAR = sodium absorption rate; TDS = total dissolved salts
Table A4.4 Hydraulic load — waterlogging: control points, preventive measures, target criteria and verification Control points Preventive measures Target criteria Verification Irrigation Irrigation tools When irrigating, apply appropriate volumes of water and use alternative irrigation methods (eg drippers) to restrict rates of water addition. Irrigation Irrigation tools Ensure irrigation scheduling methods follow best practice. Water applied is carefully calculated to match current demand, according to standard protocols (eg see 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. Soils Site selection Verify watertable is >2 m from soil surface or the lateral hydraulic conductivity of the watertable will handle required leaching fractions and irrigation rates. Groundwater Monitoring Ensure watertable remains >2 m from soil surface. Soils Drainage Subsoil drainage can be installed to increase infiltration rate and remove excess water. Delivery of correct water volumes Delivery of correct water volumes Drainage capacity of specific site appropriate Groundwater below 2 m Groundwater below 2 m Drainage greater than 5 mm/hour Soil water content remains less than field capacity, except where leaching is required. If leaching 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 becomes soft at the base or in the centre. Wilting may occur due to root decay and damaged roots blackened. Hydraulic conductivity of the soil profiles will cope with the required leaching fraction and irrigation volume required for the plants to be grown (saturated hydraulic conductivity (Ksat) at least >5 mm/hour). Groundwater remains below 2 m during irrigation and rain events throughout the year. Verify watertable in piezometer is >2 m from surface. Soil water content less than field capacity, drainage at least >5 mm/hour. Note: All control points, preventive measures, target criteria, critical limits, critical control points and their verification are site and scheme specific. The examples given in this table should be validated and verified for specific schemes. A4.3.3 Watertable rise and secondary salinity Secondary salinity is normally accompanied by waterlogging, and the relative impacts of the two u r
Table A4.9 Nitrogen — eutrophication of surface water: control points, preventive measures, target criteria and their verification Control points Preventive measures Target criteria Verification Soil Site selection In conjunction with appropriate experts, identify threats to surface waters though recycled water use on site-specific soils. Soils Buffer distances and strips Irrigation with recycled water should not be conducted directly adjacent to surface waters. Appropriate buffer distances need to be observed and buffer plantings used to strip nitrogen from runoff (Appendix 6). Diffuse and point discharge of nitrogen to sensitive environments minimised Discharges to surface waters minimised Verify that site management plan includes consideration of diffuse and point discharges to local and regional surface waters, including consultation with relevant catchment management authority. Nitrogen concentrations in nearby surface waters have not increased from baseline levels taken before development of the reuse scheme. Local waterways down slope of recycled water infrastructure and irrigation systems are buffered from discharges, and runoff to local waterways does not carry substantive nitrogen load. Irrigation and fertilisation Storage system Storage system Storage system Storage and distribution system Nutrient balancing Ensure crop nutrient budget includes inputs from all sources (water, fertilisers, soils, etc), so excess nutrients moving off-site are limited. Crops and plants grown Incorporate plants that grow in the stored water, which strip nutrients from the recycled water. Shandy with fresh water If nitrogen concentrations in stored water govern algae growth, shandy with alternative water source to decrease them. Light reduction Restriction of recycled water to light sources will minimise algal growth (eg a sealed tank compared with an open tank). Management plan Site management plan should include consideration of off-site impacts of nitrogen from intentional or unintentional discharges of recycled water on local and regional surface water quality. Nutrients supply balance with demand from plants grown Plants grow well in storage; nitrogen concentrations decreased Nitrogen concentrations decreased to acceptable levels Algae number low enough to prevent environmental issues Off-site impact from intentional or unintentional discharges minimised Crop nutrient management plan in place and documented. Soil nitrogen levels do not exceed plant requirements. Nitrogen concentrations in storage water decreased relative to inlet water and algal growth minimised. Nitrogen concentrations in storage water decreased relative to inlet water and algal growth minimised. No algae blooms. Impacts of nitrogen on surface waters recognised in the management plan and strategies for dealing with intentional or unintentional discharges developed in conjunction with local catchment management authority.
Figure A4.2 Relationship between sodium adsorption ratio (SAR) and electrical conductivity (EC) of soils and likelihood of soil structure breakdown 14.0 22.0 26.0 2.0 10.5 16.5 19.5 1.5 7.0 11.0 13.0 1.0 3.5 5.5 6.5 0.5 0.0 0.0 0.0 0.0 of dispersive soils 0 3 6 9 12 15 SAR 1:5 0 5 10 15 20 25 30 Soil SAR1:5 or ESP ESP Note: This figure can also be used as a guide to sodicity risk from irrigation with recycled water, assuming an irrigation leaching fraction of 0.25 and an EC of the irrigation water equivalent to the ECe of the surface soil (not EC1:5). Source: adapted from Rengasamy et al (1984), Cass et al (1995), Peverill et al (1999), Stevens et al (2003) The SAR of recycled water in Australia is in the range 2.6–20, averaging 6, with salinity averaging 1.2 dS/m. Applying these data to Figure A4.3 shows that irrigating with recycled water has associated sodium problems, which need to be managed. C c t r L
Moderate Moderate Irrigation and fertilisation Nutrient balancing Rare Moderate Low Unlikely Moderate Moderate Soils Management plan Unlikely Moderate Moder ate Table A4.17 (continued) Moderate Soils Buffer distances and strips Unlikely Moderate Moder ate Storage Water bodies Biota — Moderate Moderate Surface water Monitoring Rare Moderate Low Eutrophication Possible Moderate High Storage system Crops and plants grown Unlikely Minor Low system aquatic Moderate High Storage system with fresh water Unlikely Minor Low Possible Moderate High Storage system Irrigation tools Unlikely Minor Low Possible Moderate High Storage system Irrigation tools – Possible Moderate High Storage system Light reduction – Discharge (unintention Minor Moderate Storage and distribution system Buffer distances and strips Unlikely Minor Low c c s u s s u s t t r r o o p p E
A5.3 Boron Table A5.3 Maximum boron concentrations in irrigation or soil water tolerated by a variety of crops, without reduction in yields Species name Common name Very sensitive (threshold 0.3–0.5 mg/L) Citrus limon Lemon Rubus sp Blackberry Sensitive (threshold 0.5–0.75 mg/L) Persea americana Avocado C. x paradisi Grapefruit C. sinensis Orange Prunus armeniaca Apricot P. persica Peach P. avium Cherry P. domestica Plum Diospyros kaki Persimmon Ficus carica Fig, kadota Vitis vinifera Grape Juglans regia Walnut Carya illinoinenis Pecan Allium cepa Onion A. sativum Garlic Ipomea batatas Sweet potato Triticum aestivum Wheat Helianthus annuus Sunflower Vigna radiata Bean, mung Sesamum indicum Sesame Lupinus hartwegii Lupine Fragaria sp. Strawberry Helianthus tuberosus Artichoke, Jerusalem Phaseolus vulgaris Bean, kidney P. vulgaris Bean, snap P. lunatus Bean, lima Arachis hypogaea Peanut Moderately sensitive (threshold 1.0–2.0 mg/L) Brassica oleracea botrytis Broccoli Capsicum annuum Pepper, red Pisum sativa Pea Daucus carota Carrot Raphanus sativus Radish Solanum tuberosum Potato Cucumis stivus Cucumber Lactuca sativa Lettuce Moderately tolerant (threshold 2.0–4.0 mg/L) Brassica oleracea capitata Cabbage B. rapa Turnip Poa pratensis Bluegrass, Kentucky Hordeum vulgare Barley Vigna unguiculata Cowpea Avena sativa Oats Zea mays Corn Cynara scolymus Artichoke Nicotiana tabacum Tobacco Brassica juncea Mustard Melilotus indica Clover, sweet Cucurbita pepo Squash
Table A5.3 (continued) Species name Common name Cucumis melo Muskmelon B. oleracea botrytis Cauliflower Tolerant (threshold 4.0-6.0 mg/L) Medicago sativa Alfalfa Vicia benghalensis Vetch, purple Petroselinum crispum Parsley Beta vulgaris Beet, red B. vulgaris Sugar beet Lycopersicum Tomato Very tolerant (threshold 6.0–15.0 mg/L) Sorghum bicolor Sorghum Gossypium hirsutum Cotton Apium graveolens Celery Asparagus officinalis Asparagus Note: Boron tolerance may vary, depending upon climate, soil conditions and crop variety. Source: Maas (1986, 1990b); Keren and Bingham (1985). Table A5.4 Maximum boron concentrations in irrigation or soil water tolerated by a variety of ornamentals, without reduction in yields Species name Common name Very sensitive (threshold <0.5 mg/L) Mahonia aquifolium Oregon grape Photinia x fraseri Photinia Xylosma congestum Xylosma Elaeagnus pungens Thorny elaeagnus Viburnum tinus Laurustinus Ligustrum japonicum Wax-leaf privet Feijoa sellowiana Pineapple guava Euonymus japonica Spindle tree Pittosporum tobira Japanese pittosporum Ilex cornuta Chinese holly Juniperus chinensis Juniper Lantana camara Yellow sage Ulmus americana American elm Sensitive (threshold 0.5–1.0 mg/L)a Zinnia elegans Zinnia Viola tricolor Pansy V. odorata Violet Delphinium sp Larkspur Abelia x grandiflora Glossy abelia Rosmarinus officinalis Rosemary Platycladus orientalis Oriental arborvitae Pelargonium x hortorum Geranium Moderately sensitive (threshold 1.0–2.0 mg/L)a Gladiolus sp Gladiolus Calendula officinalis Marigold Euphorbia pulcherrima Poinsettia Callistephus chinensis China aster Gardenia sp Gardenia Podocarpus macrophyllus Southern yew Syzygium paniculatum Brush cherry
verification of drinking water quality An assessment of the overall performance of the water supply system and the ultimate quality of drinking water being supplied to consumers; incorporates both drinking water quality monitoring, and monitoring of consumer satisfaction. virus Molecules of nucleic acid (RNA or DNA) that can enter cells and replicate in them. waterlogging Saturation of soil with water. water recycling A generic term for water reclamation and reuse. It can also be used to describe a specific type of ‘reuse’ where water is recycled and used again for the same purpose (eg recirculating systems for washing and cooling), with or without treatment in between. watertable Groundwater in proximity of the soil surface with no confining layers between the groundwater and soil surface. zooplankton The animal portion of plankton.