Att12 - Emergency Management Plan

Emergency Management Plan
Lot 7 on RP216403, Lot 394 on M371117, and Lot 650 on M37380 – 48-59 Kabi Road, Cootharaba


Emergency Events
FLOODWATERS

Given the extent of the total catchment affecting the site (some 138 ha), the site is subject to
substantial overland flows. Due to the steepness of the catchment area, overland flows are
expected to be quick to accumulate on site and also quick to disperse downstream, unless captured
on site. In overland flow paths and site flat spots rapid rising of stormwater may occur in heavy
rainfall. This may lead to some access tracks and paths being cut off for periods during heavy
rainfall events. Due to the rural nature of the catchments, it is also possible that ground water will
continue to affect the site for some time after the cessation of rainfall.
Preliminary calculations of the depth of flow indicate that overland flows are likely contained within
existing flow paths within the site. A high-level catchment assessment reviewing the critical
locations (low points and extended flat areas) indicates that inundation up to 300mm deep may
occur at some locations. Future proposed accommodation and infrastructure should be kept clear
of these areas, as is indicated in the Layout plans by Elevation Architecture.
The preliminary calculations also indicated that the site access may be inundated during
heavy rainfall events. This was confirmed by the heavy rainfall experienced during February
2022 with reports from onsite that the entry was indeed inundated for a period of time. The
estimated calculated flow depth is in the order of 50mm, which is not considered deep for
trafficability. The estimated velocity is around 2m/s with a velocity depth product
approaching 0.1 m2/s. It may be that this inundation is considered trafficable and/or only
occurs for a short period and therefore does not substantially limit access to the site. However
further calculation and assessment as part of future design should be undertaken to confirm the
impact on the site and site operations.
A review of Councils flooding overlay mapping was undertaken which illustrated that various
routes local to the site are subject to flowing in a 1 in 100-year storm event. The following
access points flood / affected by a waterway (see Figure 2):
       - The intersection of Cootharaba Road and Lake Flat Road, approximately 1.5-2.0 km
       northwest of the site.
       - The intersection of Road 176 and Cootharaba Downs Road floods, approximately 0.9-
       1.3 km Southeast of the site.
       - Cootharaba Road is affected by waterway, approximately 1.6-1.9 km from the
       Southwest from the site.
       - The intersection of Junction Road and Loui Bazzo Drive, approximately 4.5-5.0 km
       south of the site.
The initial review indicates that there is not a flood free route for the site in the event of a
significant flood. Therefore, this EMP has been prepared to assist with site management during
potential flood events along with other emergencies.