AS/NZS 5667.1 means Australian Standard AS/NZS 5667.1 Water quality – Sampling – Guidance in the design of sampling programmes. The application will incorporate the infrastructure built as part of upgrades to the existing treatment plant under Works Approval W and seeks approval for the irrigation of treated waste water on the oval and golf course, which surrounds several of the islands' salt lakes. There are five sanctuary zones, the closest of which is approximately 600 m northeast of the oval.
A portion of the north-west portion of the golf course is located in a Priority 3 PDWSA (Hole 5 Tee, Hole 6 Green and Hole 7 Tee). DWER intends to undertake a detailed risk review of the existing License to harmonize it.
Decision
Infrastructure and operations
As described in Table 10, the data presented in the Water and Nutrient Balance provided in the RWQMP (Permeate Partners, 2016) indicate that the treated wastewater will not be irrigated during the months of May – August inclusive. The delegated official has determined that irrigation can be done within these months provided that soil moisture meters determine the capacity of the field that can accept the irrigated water. Therefore, the Delegated Official has determined that regulatory controls are required to further manage the risks associated with oval and golf course discharges to prevent overuse of treated wastewater when there is no on-site field capacity left. of irrigation areas.
The delegated official has determined that based on the results of the risk assessment that regulatory controls are required through the conditions of license for the total amount (loading) of nitrogen and phosphorus applied to the oval and golf course irrigation areas. To meet the nutrient loading limits set out in Condition 6, the Delegated Officer also considers it appropriate to ensure that irrigation activities are not carried out where soils are equal to or greater than field capacity. The Licensee may wish to use the measurements taken in the 2012 soil investigation or use the new samples taken in September 2017 to determine the updated Field Capacity measurements.
As identified in the risk assessment, elevated zinc levels in groundwater have the potential to affect hyporheic fauna (stygofauna that live in sediments surrounding salt lakes) and microbial mats surrounding salt lakes. The intermediate management incentive levels for N and P defined in Table 7 of the NIMP may be protective in the short term, but may not be protective against microbial beds and stygofauna. These are likely to be caused by natural processes (reductive dissolution of arsenic-bearing iron oxides at depth in sediments), but there is a risk that high BOD levels in groundwater contaminated by sewage components (high load of organic carbon) may release arsenic to shallower depths in this saline lake in the long term.
The delegated officer notes that with the exception of soil moisture monitoring as specified in Condition 19, the monitoring requirements are consistent with the commitments made by the license holder in the Application.
Licence Holder’s comments
Amendment
In the event of an overflow, the waste water must be led to the emergency basin. A jet mixer should be used to keep solids in suspension and prevent short circuits in the flow balancing tank. Waste water routed to the emergency storage basin must be pumped back to the flow balance tank for treatment when capacity is available.
Agitators should be used to suspend solids and ensure good contact between the incoming wastewater and the mixed liquor. In case of overflow, the treated wastewater should be directed to the Emergency Storage Basin. 12 Chemical storage tanks - should be of sufficient size to hold chemical volumes for 30 days of continuous operation of the waste water treatment plant and be located in separate joint areas in accordance with AS3780-2000: Storage and treatment of corrosive substances.
Must be in operation when screening activities take place and/or the Flow balance tank contains waste water. Full sludge holding tanks shall be stored on a hard concrete base provided with a 600mm wide x 50mm high roller bottom and drained to the plant sump. Sprinklers shall be operated to ensure that wastewater is evenly distributed to the designated irrigation areas as depicted in Schedule 1; Map of 'Golf Course and Oval Irrigation Areas'.
The Licensee must only irrigate treated waste water to the defined irrigation areas as depicted in Appendix 1 in the 'Oval and Golf Course Irrigation Areas' map.
General monitoring
The licensee must demonstrate compliance with the limits set out in Condition 5 by:. a) conduct monitoring in accordance with Condition 13; And. The permit holder must establish baseline field capacity measurements for the soil sampling sites as described in Condition 19 before irrigation of treated waste water commences. Licensee must ensure that irrigation of treated waste water to the golf course and oval does not occur when the soil moisture content (v%) is equal to or greater than the base field capacity as defined in Condition 7.
The Licensee must demonstrate compliance with Condition 8 by undertaking monitoring in accordance with Condition 19. W8(a) The Licensee shall collect all water and waste water samples in accordance with the relevant part of the Australian Standard or other standards approved. All water and wastewater samples required by these license conditions shall be analyzed in a NATA-accredited laboratory for the parameters specified in accordance with the APHP-AWWA-WEF Standard Methods for the Examination of Water and Wastewater. and replaced by Condition 10 as shown below:.
W5 The licensee shall collect treated wastewater samples from the treatment plant at the sampling point on a monthly basis, at a time when the treated wastewater discharge can be assumed to be representative of the discharge conditions in stable and will be analyzed to determine the levels of the following parameters: iv) 5-day biochemical oxygen demand (BOD5); vii) Nitrate plus Nitrogen Nitrite; and (viii) Total phosphorus. With the exception of pH, all measurements should be reported in milligrams per liter (mg/L).
Wastewater discharge quality criteria and monitoring
The licensee must ensure that the accuracy of the flow meter device required under condition 12 and 13 is carried out in accordance with the Australian Technical Standards and Australian Standards specified in "Guidelines for Water Meter Installation" Department of Water, 2009). W7 The licensee must take representative water samples from the groundwater monitoring boreholes every 6 months and have them analyzed for the following parameters:. i) Standing water level (determined before collection of water samples); iv) Total dissolved solids; and. All measurements must be reported in milligrams per liters (mg/L), except for SWL (meters AHD), pH and thermotolerant coliform bacteria, and must be included in the annual monitoring report. and replaced by condition 15 as follows:.
W6 The licensee shall maintain one groundwater monitoring pit (background) of the infiltration basins and two groundwater monitoring holes at the bottom of the infiltration basins. and replaced by Condition 16 as follows:. The Licensee shall maintain the monitoring holes referred to in column 1 of table 6 and as described on the map in table 1, in good working order to allow representative water samples to be taken. The licensee must undertake monitoring of freshwater lenses/hyporheic zone. a) in the countries specified in column 1;.
Each composite sample must be derived from five cores at four depth intervals up to one meter, within a five meter diameter plot. The report will contain data collected from 1 July to 30 June and will be provided by 30 September each year.
Information and Reporting
- MAPS
- Key documents
- Summary of Stakeholder comments
- Summary of Licence Holder comments
Licensee must comply with a CEO request within 7 days from the date of the CEO request or such other period specified in the CEO request. Effects on ecology and water resources The irrigation and nutrient loading of the proposed recycling scheme may have a negative impact on the ecology of Rottnest Island's salt lakes. The department is unable to quantify the extent of the ecological impacts on the lakes with the available data and cannot provide acceptable long-term limit values for nutrient loading.
This monitoring should be used to improve the understanding of the benthic algal mat community's response to additional nutrient inputs (especially phosphorus). A small section of the island's golf course (including sections for holes 4, 6 and 7) is located within the southern boundary of the Longreach Bay saltwater drilling field (P3 area). Following the granting of this amendment notice, DWER intends to undertake a detailed risk review of the license to align it with DER's risk-based regulatory framework.
The risk assessment as described in Table 8 has only considered the possible impact of the irrigation of treated waste water to the golf course with a time-limited approval of six months. It is not clear whether the latest schedule update has been reviewed by the DoH. Conduct a risk assessment, unless already done as part of another report, to identify potential risks to the quality of the public drinking water source; And.
Continue monitoring to establish groundwater quality trends near the discharge areas along the boundary of the Longreach Bay saline well field and make this available to the Department of Water if required. Increasing the width of the salt marsh buffer to reduce hydrological risks to microbial assemblages and other biota, particularly in Havesøen. Following the award of this change notice, DWER intends to conduct a detailed risk review of the license to align it with DWER's risk-based regulatory framework.
