08/1128 - Response to Information Request [As Published] · 132008.1128

ADDITIONAL INFORMATION FOR ITEM 40 - STORMWATER

The basement level of the proposed Residential Aged Care facility is RL 27.6mAHD. The base level
of the bio-retention basin to which its basement drains (Lot 6) is RL 27.0mAHD. Therefore, the
basement would drain under gravity. The pipe grade would be 0.8%, which is above the 0.5%
minimum as specified in the QUDM Table 7.12.1. The 2 year ARI tail water level in the Lot 6 basin
would be RL 27.8mAHD (Depth=0.8m) which would result in 200mm flood depths for the 2 year
ARI event. Therefore, a non-return device is recommended to stop return flow into the basement. This
will be detailed at Operational Works.

The basement level of the proposed apartment buildings ranges from is RL 23.6 to 24.8 mAHD. The
base level of the bio-retention basin to which the apartment buildings drain (Lot |) is RL 19.5mAHD.
The grade would range from 5-13% which is acceptable under QUDM Table 7.12.1. The 100 year
ARI tail water level in the Lot 1 basin would be RL 23.16mAHD (Depth=3.66m), which provides a
minimum 0.44m freeboard to level of each apartment basement.

Information provided by Cardo
27" November 2008
$:1301 1:081128inReqCardno