LSP3
3.6 Water Management
Schedule 4 of LPS 17 sets out a framework for environmental and water management reporting for the Albion cell at DSP, LSP and subdivision stages. A Local Water Management Strategy (LWMS) was prepared and adopted as a detail of the Albion DSP, pursuant to LPS 17.
The Albion DSP LWMS was prepared in the context of existing and concurrent regional and district ground water studies including; Drainage Management Strategy for the North East Corridor (GB Hill 1995) and the Swan Urban Growth Corridor Drainage Water Management Plan (DWMP) (GHD 2009).
LPS 17 Schedule 4 requires the preparation of an Urban Water Management Plan (UWMP) to support a Local Structure Plan. This is inconsistent with the hierarchy of water strategy documents outlined in the WAPC Better Urban Water Management 2008 (BUWM), which requires a LWMS to be prepared at the local structure planning level and not at the district level.
The endorsed Albion DSP sets out an agreed water management reporting framework at LSP and subdivision stages. It has previously been agreed with the City of Swan and the Department of Water (DoW) that the appropriate level and content of investigation and reporting for a LSP is a Local Water Management Strategy as described in BUWM. Urban Water Management Plans will be prepared for all subsequent subdivision application areas as a condition of subdivision approval. This is consistent with the endorsed approach that has been successfully implemented elsewhere within the DSP area.
Consistent with the agreed framework, hydrologists 360 Environmental have prepared a LWMS in support of LSP3A – refer Appendix 2. The LWMS provides a localised urban water management strategy for the site consistent with the requirements of the Albion DSP LWMS, the framework and requirements outlined in BUWM and LPS 17.
The following summarises the key outcomes and implications of the LWMS.
3.6.1 Water Conservation
At the development scale, the LWMS recommends the use of a non-potable source for establishment of open space. As discussed further below, the aquifers underlying the LSP area are fully allocated. A temporary licence application been submitted for supply of water for construction and to establish the vegetation within the POS. The vegetation species will be selected to be drought tolerant and not require any ongoing irrigation, thereby ensuring that ongoing water consumption for the project is limited to individual consumption of scheme water.
The LWMS identifies a range of best practice water conservation measures at a local (individual lot) scale, including:
• Showerheads installed with a rating better than the minimum WELS 3 Star.
• Taps installed with a rating better than minimum WELS 4 Star.
• Dual flush toilets with a rating better than minimum WELS 4 Star.
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• Water using appliances, such as washing machines and dishwashers installed with a rating of WELS 4 Star or better.
• Baths and Spas are low volume and small surface area.
• Hot water systems located less than 20m from the point of use and / or a recirculation or heat pump is installed.
Conservation measures for external household use include:
• Garden designs will incorporate waterwise or endemic plant species.
• Garden beds will be mulched to a minimum of 5cm with Smart Approved WaterMark mulch.
3.6.2 Surface Water Management
The LWMS identifies the following key strategies for the management of surface water / storm water:
• Maintain the existing catchments and flow paths across the north and south of the LSP area through earthworks and alignment of road networks;
• Adopt a ‘treatment train’ approach to water quality management and protection of receiving environments, including infiltration of frequent events close to source and bio-retention areas to strip nutrients;
• Frequent events (≤1yr ARI Event) infiltrated within the majority of lots through the use of soakwells, with runoff from roads infiltrated via a bio-retention system within either public open space or roadside swales;
• Smaller lots (<300m²) will have lot connections to the street drainage network, removing the need for soakwells within the lot, and ensuring that the water will be treated and infiltrated in bio-retention areas within open space and / or roadside swales;
• Major events will be discharged offsite at near pre-development peak flow rates;
• Attenuation of discharge offsite to reflect pre-development hydrology will be achieved with the use of a drainage infrastructure (swales and basins);
• Modification of St Leonards Creek to formalise the channel morphology, provide the community with amenity and provide similar hydraulic performance; and
• Modification of the Woollcott Avenue drain with general road upgrades to convey arterial runoff downstream (final form, either drain or pipe, to be determined in detailed engineering design).
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www.cleplan.com.au
3403-31-01 (01.09.2015), Nts
This plan has been prepared for general information purposes only and uses potentially uncontrolled data from external sources. CLE does not guarantee the accuracy of this plan and it should not be used for any detailed site design. This plan remains the property of CLE.
Source: 360 Environmental
3403Rep7A 49 A major and minor approach to the design of stormwater management systems has been
adopted for the LSP area. The minor system consists of underground pipes, kerbs and gutters deigned to convey runoff up to the 5yr ARI event and ensure serviceability of the road network. The major system consists of roads, swales, open space, St Leonards Creek and the Woollcott Avenue Drain, and provides protection to the community from extreme flooding events (up to the 100yr ARI event) that exceed the capacity of the minor system. Figure 17 – Conceptual Stormwater Management Plan demonstrates the integrated nature of the minor stormwater management system.
As demonstrated in Figure 17, the LSP responds to these key principles through the location of public open space at the low point in each drainage catchment, and ensuring that each area of open space that serves a drainage function is appropriately sized and dimensioned in order to improve efficiency and maximise functionality of the open space. Further discussion on the stormwater management system is provided in the LWMS at Appendix 2.
3.6.3 Groundwater Management
The LSP provides adequate clearance to maximum ground water level (MGL) through the importation of sufficient fill to ensure at least 1.5m of clearance. This removes the requirement for sub-soil drainage and ensures a low maintenance, low risk solution to the management of groundwater.
Quality of groundwater will be maintained or improved through the use of bio-retention areas which will treat storm water and remove nutrients before discharging into the broader system.
3.6.4 Groundwater Abstraction Licences / Irrigation Supply
The LSP has been designed specifically to minimise the need for an ongoing irrigation water supply. As noted above, the underlying aquifers are fully allocated at present, creating opportunities for a range of waterwise landscape treatments throughout the open space areas. These waterwise open space areas are complementary to the 3.12ha of active open space located immediately to the west of the LSP area, which will cater for active recreation uses that require irrigated turf areas.
www.cleplan.com.au
3403-31-01 (01.09.2015), Nts
This plan has been prepared for general information purposes only and uses potentially uncontrolled data from external sources. CLE does not guarantee the accuracy of this plan and it should not be used for any detailed site design. This plan remains the property of CLE.
Source: 360 Environmental
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