RFI - Attachment F - Engineering Report

particles less than 1mm are classified as suspended solids and particles greater than 5 mm
are considered gross pollutants ( T. Wong, CRC Catchment Hydrology, pers.com)

Total Nitrogen and Total Phosphorous was measured in particles under 1000 µm and
material over 1000 µm (1180µm screen actually used to meet the AS1289 3.6.1 Soils
analysis). Gross pollutants will be classified as particles over 4750 µm because of the
available sieve sizes.

Catchments
Three sub catchments were defined, commercial (Comm.), urban (Urban) and urban base
(Base), based on the differences in each catchment characteristics.

Urban and urban base sub catchments have essentially the same type of residential land
use, however the urban catchments is located on grade, with a moderate to steep
catchment grade. It was thought prior to the study that there would be a noticeable
difference in the type of material collected in each unit due to the steepness of the grade
mobilising different size particles. The other main difference with the urban sub
catchment is the pedestrian use. It was observed the urban sub catchment had a higher
pedestrian use the urban base sub catchment as pedestrians would use the area to park
cars.

The commercial sub catchment is situated at the top of the catchment and collects
stormwater runoff from retail outlets along the Pacific Hwy and from light
industrial/commercial properties in the north-west corner of the study area. This sub
catchment has high levels of pedestrians associated with the use of the retail areas and the
nearby train station.

Traffic flow in the area was observed to be moderate (based on a visual assessment of the
frequency of vehicles in comparison to other Enviropod projects) on all streets, with the
exception of several “No Though Road” streets, which had fewer vehicles and the Pacific
Hwy, which has high to very high vehicle movements.


Contaminant Characteristics
Enviropod Removal Loads
The following table indicates the total mass removed from all units as part of each
monitoring event. The total load removed during the study period was approximately
10.5 tonnes.




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