RFI - Attachment F - Engineering Report

Figure 1: Sediment removal by the Gullypit Containing an Enviropod Filter with a 200 micron mesh
                                       (Tonkin & Taylor)

Project Methodology
The Blackbutt Creek catchment was separated into three different reticulated sub-
catchments. Each sub-catchment was characterised by the different types of land use and
geographic characteristics within the catchment. Different land uses and geographic
characteristics (in this case catchment grade) produce contaminants at different rates

It was proposed to clean all Enviropods in the catchment together, on approximately 2-
month cycles, however at the time of monitoring this was increased due to the high
loading of many of the Enviropods. Not all Enviropods were cleaned during each event
due to access problems associated with cars parked on pits and other obstructions.

As part of the cleaning, 5 samples were taken from the retained material from each sub-
catchment on every alternative clean i.e. 15 samples were collected from the Blackbutt
catchment. The 5 samples from each sub-catchment were combined in a composite
sample and sent to a NATA approved laboratory for grain size distribution. The grain
size distribution was conducted to examine the type of material collected in the
Enviropod filter and define the suspended solid load such that it is consistent with the
CRC catchment hydrology definitions of Suspended solids and the definitions for the
CRC “Music” modelling programme. The “Music” modelling package has assumed that



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