EagFirRsp

The pre- and post-development overflow rates are summarised in Table 3 below

Nett Result: Complete impact mitigation; substantial benefit

Table 3: Overflow Rates Through The Park, Nodes N34 to N22
 Event                Pre-Development       Post Development
 AEP (ARI)            (m3/s)                 (m3/s)
 AEP 1% (100 yr)      1.70                   1.60
 AEP 2% (50 yr)       1.37                   1.23
 AEP 5% (20 yr)       1.13                   0.92
 AEP 10% (10 yr)      0.76                   0.51
 AEP 20% (5 yr)       0.36                   0.13
 AEP 50% (2 yr)       0.02                   0.00
 AEP 67% (1yr)        0.01                   0.00


Overflow Rates Across Tait Street, Nodes N22 To N17.

In the pre-development scenario, these include the flows from the Eagle Drive sag (as in Table 3 above) plus
surface runoff from the park and Tait Street, less flows collected into the underground system at the Tait
Street kerb. In the post-development scenario, the flows from the Eagle Drive sag are replaced by the
overflows from the detention basin. The impacts broadly mimic those in Table 3 above, with details as
summarised in Table 4, below.

Nett Result: Complete impact mitigation; substantial benefit

Table 4: Overflow Rates Across Tait Street, Nodes N22 To N17.
 Event                Pre-Development        Post Development
 AEP (ARI)            (m3/s)                  (m3/s)
 AEP 1% (100 yr)      1.73                   1.59
 AEP 2% (50 yr)       1.23                   1.04
 AEP 5% (20 yr)       0.87                   0.65
 AEP 10% (10 yr)      0.48                   0.30
 AEP 20% (5 yr)       0.16                   0.08
 AEP 50% (2 yr)       0.00                   0.00
 AEP 67% (1yr)        0.00                   0.00


Overland Flows Through The Tait Street Properties, Around Nodes N45 to N50

In the pre-development scenario, these flows comprise the overland sheet flows from the subject development
site and the neighbouring property to the east of the site, apart from a small proportion of that flow that
follows the existing driveway swale out to Eagle Drive.

In the post-development scenario, the contributing catchment area is reduced by about two thirds and the
overland flow rates are reduced even further by the underground piping of roofwater from the remaining area.



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BSM Doc File EagFirResp.Doc