Attachment 4 - Stormwater Managment Plan

4.4. SITE WSUD TREATMENT MEASURES
Each proposed driveway stormwater pit will have a SPEL Stormsack installed (refer to Appendix
A for further details) or an approved equivalent. These storm sacks are fitted into each drainage
pit to capture the gross pollutants (ie: sediment, litter, oil and grease) at the source. They are
easy to clean and maintain, and have the below features as seen in Figure 6.




Figure 6; SPEL Stormsack product features.
The final piece of the treatment train is the SPELBasin; which is a SQIDEP approved modular
Bioretention System, refer to Appendix B for further information and below in Figure 7 for a
table of the treatment efficiencies provided by this unit. Its size and capacity make it an ideal
solution for stormwater treatment trains that require a high pollutant reduction in a small
footprint. It can be used in place of standard catch basin structures, rain gardens, bioretention
cells and media filters. As a self-contained treatment train, it incorporates the following
treatment components screening, hydrodynamic separation, media filtration and a bioretention
filter. Given the subject site characteristics, ie: existing and proposed site levels/contours,
locations of the proposed landscaped areas, location of the proposed legal point of discharge,
location and depth of the existing sewer pipe traversing through the site etc… it would not be
possible or preferable to install a non-proprietary raingarden or bioretention system in the
landscaped area. As this product is a self-contained SQIDEP approved treatment module, can be
built into the landscaped area; it is the preferred system to be adopted on this particular site. It
will also make future maintenance easier due to the modular chambers of the design making it
simple to maintain given the surrounding driveway and footpath areas.




Figure 7; SPELBasin product features.
The SPELBasin can be easily integrated within the proposed landscaped area and will have a
suitable by-pass pit/pipe system for larger site stormwater flows. The SPELBasin will be planted
with specific plant species that thrive in Bioretention environments- refer to the proposed
Landscaping Plan for further details. Maintenance for the above unit/s shall be in accordance
with SPEL Stormwater requirements.

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             TMC Building Design Group