Draft Condition Response CT · REC13/0015

 

(iv) are designed to ensure that flows which exceed the treatment capacity of
the device avoid damaging of the filter media or subjecting the filter
media to excessive sediment loads.

(v) are provided with a free-draining outlet from the sub-soil drainage system

The current Bio-Retention Guidelines (Water By Design, Version 1 October 2012) states that a
coarse sediment forebay is not required for catchments less than 2 Hectares (Table 14 on page
69). The catchment area is 0.372 Ha and therefore a sediment forebay is not required and
should be deleted from Condition 11 as shown above.

It then follows that an access driveway right down to the bio-retention basin to remove sediment
from a forebay is not required when a forebay is not installed. Figure 34 of the Bio-Retention
Guidelines (Water By Design, Version 1 October 2012) sets out access track requirements for a
forebay, however without a forebay these requirements are not applicable and we request that
Condition 1 should be revised as shown above.

Yours faithfully,
Callaghan & Toth

 

A Haynes BE Civil (Hons) RPEQ MIEAust CPEng

Please view www.callaghanandtoth.com.au for all information on our company profile and terms and conditions for services rendered

Cc Alex Mc Williams
Max Watterson

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