Reference Document MCU22/0102 Stormwater Management Plan

                                     To ensure effective      Flow then enters the biofiltration chamber via a pipe
                                     functioning of           located at the base of the structure, and is distributed
                                     the biofiltration        throughout the filter media through a HDPE geo-grid
                                     system, standard         fitted to the perimeter walls (4). Stormwater filters
                                     specifications of        through the proprietary media blend horizontally and
                                     the soil media have      into the centrally-located, slotted collection pipes (5)
                                     been developed           that discharge to the outlet chamber (6). Flow finally
                                     (FAWB, 2009).            enters the underground stormwater drainage system
                                     These specifications     through a discharge pipe (7) that is controlled by an
                                     require traditional      offset outlet from the base to create a permanently
                                     biofiltration systems    submerged zone. These are shown in Figure 3.
                                     to implement three
                                     layers of media, as      1.3 DESIGN DRAWINGS/DIMENSIONS
                                     indicated in Figure 2.
                                                              A standard drawing of the SPELBasin® is shown in
FIGURE 2.                                                     Figure 4. The SPEL basin has an overall length, width
BIOFILTRATION MEDIA LAYERS SECTION                            and height of 6120 x 1340 x 1300 mm respectively. The
                                                              system allows for stormwater runoff to enter via a kerb
These three layers then have a detailed specification         inlet, a grated inlet or underground pipe. The kerbtype
that describes the particle size distribution, nutrient       inlet and grated inlet are fitted with a 600 x 600 mm
content and desired permeability to achieve the               PEL StormSack which filters gross pollutants from
stormwater treatment goals.                                   stormwater inflow.

1.2 MODULAR BIOFILTRATION                                     Pre-filter cartridges are situated within the pre-
                                                              treatment chamber to further remove coarse sediment
The SPELBasin® modular biofiltration system has               from stormwater that bypasses the StormSack. Flow
a number of similar design features to a traditional          is horizontally dispersed through a 7.3 m3 biofiltration
biofilter, however, differs in two key areas;                 system with a proprietary biofiltration media blend
                                                              which drains treated stormwater into the 1.56 m3
•   the use of a proprietary media blend; and                 discharge chamber. Treated water is discharged
•   horizontal flow instead of top-down flow;                 through outlet pits and to street drainage.

The treatment process provided by the SPELBasin®
commences with runoff entering via a kerb inlet (2),
grated inlet or pipe network, and passing through
a coarse sediment screen in the pre-treatment
chamber (3).




                                                                                                  FIGURE 3.
                                                                                                  SPELBASIN® SCHEMATIC




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