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MCU14-0039 Flood report and flood man Plan rev August 2015
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Log in to see the plans as drawnGia WATER TECHNOLOGY WATER, COASTAL & ENVIRONMENTAL CONSULTANTS 305 LAKE MCDONALD DRIVE COOROY FLOOD IMPACT ASSESSMENT AND FLOOD MANAGEMENT PLAN Nate August 2015
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Como Glasshouse P/L C/‐ Martoo Consulting P/L
Flood Impact Assessment – 305 Lake McDonald Drive Cooroy
DOCUMENT STATUS
Version Doc type Reviewed by Approved by Distributed to Date issued
v02 Report AJT AJT Como 31/08/2015
Glasshouse P/L
C/‐ Martoo
Consulting P/L
PROJECT DETAILS
Flood Impact Assessment – 305 Lake McDonald Drive
Project Name
Cooroy
Client Como Glasshouse P/L C/‐ Martoo Consulting P/L
Client Project Manager Nadine Gorton
Water Technology Project Manager Alister Daly
Report Authors Andrew Thompson
Job Number 3917‐01
Report Number R01
Document Name Flood Impact Assessment and Flood Management Plan
Cover Photo: Existing site greenhouse (Source – Martoo Consulting)
Copyright
Water Technology Pty Ltd has produced this document in accordance with instructions from Como Glasshouse P/L C/‐
Martoo Consulting P/L for their use only. The concepts and information contained in this document are the copyright of
Water Technology Pty Ltd. Use or copying of this document in whole or in part without written permission of Water
Technology Pty Ltd constitutes an infringement of copyright.
Water Technology Pty Ltd does not warrant this document is definitive nor free from error and does not accept liability for
any loss caused, or arising from, reliance upon the information provided herein.
93 Boundary Street
West End QLD 4101
Telephone (07) 3105 1460
Fax (07) 3846 5144
ACN No. 093 377 283
ABN No. 60 093 377 283
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Como Glasshouse P/L C/‐ Martoo Consulting P/L Flood Impact Assessment – 305 Lake McDonald Drive Cooroy TABLE OF CONTENTS 1. Introduction .................................................................................................................... 3 1.1 Background .............................................................................................................................. 3 1.2 Purpose and Intent .................................................................................................................. 3 2. FLOOD IMPACT ASSESSMENT .......................................................................................... 4 2.1 Site Description........................................................................................................................ 4 2.2 Available Data .......................................................................................................................... 5 2.3 Hydraulic Assessment .............................................................................................................. 5 2.4 Hydraulic Results ..................................................................................................................... 7 2.5 Conclusions and Recommendations ....................................................................................... 8 2.5.1 Summary of Findings ............................................................................................................... 8 2.5.2 Recommendations................................................................................................................... 8 3. FLOOD MANAGEMENT PLAN ........................................................................................... 9 3.1 Introduction ............................................................................................................................. 9 3.2 Operational Details .................................................................................................................. 9 3.3 Flood Risks ............................................................................................................................... 9 3.3.1 General Site Flood Risks .......................................................................................................... 9 3.3.2 Flooding at the Site ................................................................................................................ 10 3.3.3 Access to Site ......................................................................................................................... 10 3.4 Management of Hazardous Materials and Chemicals .......................................................... 10 3.5 Flood Emergency Management Strategy .............................................................................. 11 3.5.1 Method .................................................................................................................................. 11 3.5.2 Flood Triggers ........................................................................................................................ 11 3.6 Flood Refuge .......................................................................................................................... 12 3.6.1 Procedures ............................................................................................................................. 12 3.7 Flood Monitoring and Emergency Services Contacts ............................................................ 14 4. CERTIFICATION ...............................................................................................................14 Appendix A SITE LAYOUT PLAN Appendix B HYDRAULIC MODEL RESULTS Appendix C FLOOD MANAGEMENT PLAN DETAILS LIST OF FIGURES Figure 1 – Site layout and locality ........................................................................................................... 4 Figure 2 – Greenhouse Internals ............................................................................................................. 6 LIST OF TABLES Table 3‐1 Contact Details and Information ................................................................................. 14 3917‐01 / R01 v02 ‐ 31/08/2015 2
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Como Glasshouse P/L C/‐ Martoo Consulting P/L
Flood Impact Assessment – 305 Lake McDonald Drive Cooroy
1. INTRODUCTION
1.1 Background
Water Technology Pty Ltd (WT) has been commissioned by Como Glasshouse P/L on behalf of Martoo
Consulting Pty Ltd (Martoo) to undertake a flood impact assessment and flood management plan for
an existing Greenhouse structure located at the D’VineRipe Tomato Farm, 305 Lake McDonald Drive
Cooroy.
A development application under Council file reference MCU14/0039 for a Material Change in Use
application has been previously submitted to Noosa Council in 2014. We understand that this
application was made following Council’s determination that the since constructed greenhouse at the
site was deemed to be an intensification of use and accordingly required development approval.
Council has since issued an Information Request (IR) for the application dated 25 June 2014 under
Council reference 01569. This IR requested further information against a number of items and in the
context of flooding included a flood impact assessment as well as a flood management plan under
Items 1 and 2.
1.2 Purpose and Intent
This report has been prepared to specifically address Items 1 and 2 of Council’s IR dated 25 June 2015.
Accordingly, this report has been prepared in 2 distinct chapters as follows: ‐
Chapter 2 – Flood impact assessment, which includes the following: ‐
Background information;
Site description;
Summary of hydraulic modelling methodology;
Overview of modelling results (existing and post‐developed); and
Discussion of impacts.
Chapter 3 – Flood Management Plan, which includes the following: ‐
Available flood warning at the site;
Rate of rise of flooding;
Evacuation routes and egress;
Measures to protect the existing infrastructure during flood events; and
Appropriate strategy and site specific measures to minimise flood risks at the site and
potential contamination from hazardous material stored at the site.
Further details relating to the methodology and findings for the assessments are discussed separately
in the chapters of this report which follow.
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2. FLOOD IMPACT ASSESSMENT
2.1 Site Description
The site is approximately 33 hectares in area and is located some 3.3 km north‐east of the township
of Cooroy. The site is currently used for rural and agricultural purposes, and includes a since
constructed greenhouse approximately 140m x 140m that is currently used to grow tomatoes. Six
Mile Creek traverses the site in a general northerly direction and the site is subjected to existing
flooding. Figure 1 illustrates the general arrangement of the site and includes the existing greenhouse
and Six Mile Creek. Existing infrastructure at the site includes the greenhouse, several smaller
equipment and storage sheds (located to the south‐west of the greenhouse) as well as associated site
access roads. Existing landuse in the vicinity of the site comprises a mixture of industrial, residential
and agricultural uses interspersed with areas of heavy vegetation. The site topography is generally flat
and low‐lying.
Site Boundary
Existing
Greenhouse
Six Mile Creek
Existing Site Access
Figure 1 – Site layout and locality
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2.2 Available Data
The following data has been sourced and used in this assessment: ‐
LiDAR topographical data sourced from the Department of Natural Resources and Mines
(DNRM);
A partial detailed survey of the subject site (provided by Martoo); and
Digital flood models and associated model files for the Six Mile Creek (Cooroy Flood Study)
sourced from Noosa Council.
By way of background to the Council flood model, the hydrological and hydraulic model developed for
Six Mile Creek as part of the Cooroy Flood Study was originally prepared by Water Technology on
behalf of the Sunshine Coast Council (SCC). The study was documented in the report entitled “Cooroy
Flood Study”, Water Technology, July 2013. The work included model calibration tasks relating to the
historical flood events which occurred in 1999, 2009 and 2012. The models developed in 2013 (XP‐
RAFTS and TUFLOW) were subsequently used by Hydrology & Water Management Consulting Pty Ltd
(HWMC) under commission from SCC in 2013 and extended to include design flood assessments for
the 1 in 2 AEP to PMF flood events. This work was documented in the report entitled “Cooroy Design
Flood Modelling” by Hydrology & Water Management Consulting Pty Ltd, November 2013 (report
J00147Lt1). We understand that the digital flood model data purchased and subsequently provided
by Council for the purposes of this current assessment is the same model prepared by HWMC in
November 2013. This model, namely the TUFLOW model, has been adopted for the purposes of this
investigation and remains fundamentally un‐changed in respect to the model details applied for this
assessment other than that the minor changes that have been outlined in this report.
2.3 Hydraulic Assessment
The Council provided TUFLOW hydraulic model was used as a basis for this investigation and revised
for the purposes of this assessment to reflect the following scenarios:‐
Existing conditions (no greenhouse structure or associated site earthworks); and
Developed case (representing the inclusion of the greenhouse structure and associated site
earthworks).
For the existing condition, the model topography was supplemented with detailed survey information
of the immediate site and surrounds. The detailed survey was included to otherwise more accurately
reflect site topography in respect to the LiDAR information contained within the model. As the
detailed survey reflects the current site conditions and therefore includes since constructed works at
the site (i.e. greenhouse, pond and associated earthworks including existing bunds), it was necessary
to modify the survey information to otherwise exclude the since constructed works and to reflect a
pre‐development site arrangement. This ensured that a representative topographic condition was
included in the existing case model with associated enhancement using the detailed site. No other
change was made to the model for the purposes of the existing case scenario. The revised model was
subsequently re‐analysed for the 10% AEP and 1% AEP design flood events to provide base case
existing flood information at the site and on which comparisons would be made to the developed case
site conditions to quantify impacts.
For the developed case, a number of model scenarios have been analysed in an iterative manner and
for the purposes of minimising flood impacts from the since constructed works. This has included: ‐
Inclusion and exclusion of since constructed earthwork bunds at the site (i.e. these being
bunds 1, 2 and 3 as illustrated on the site layout plan included in Appendix A); and
Inclusion of the greenhouse structure itself (i.e. again, illustrated on the site layout plan
included in Appendix A).
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In relation to the greenhouse structure, modelling showed that flood impacts external to the site were
unacceptable when the greenhouse was modelled as a fully blocked structure. Given the structure
construction being plastic wall sheeting, it is unlikely that the structure would in fact operate in a
manner that would preclude flooding internally and it is likely that the plastic walls would become
compromised by flood waters. Indeed, information provided from the client noted that in the most
recent historical flood event the greenhouse walls were in fact compromised with flood waters flowing
through the structure.
For the purposes of this investigation, the greenhouse structure has been modelled to allow flood
waters to pass through the structure, with the Manning’s “n” roughness increased to reflect the nature
of the internal plantings and to allow for some blockage associated with the marginal reduction in
flood conveyance associated with structure columns. Given the type of structure (plastic sheeting)
and the contents of the greenhouse (tomato plants – refer Figure 2), a Manning’s “n” roughness of
0.07 was adopted, with a sensitivity analysis also undertaken using n=0.1. This approach is considered
to be very conservative given the internal plantings currently in existence as well as the fully vegetated
conditions at full plant growth conditions likely to be encountered within the greenhouse. We
additionally note that it is intended to provide the greenhouse with lay‐down wall sections to the
height of the 1% AEP flood depth to facilitate flood water flows through the structure during times of
significant flooding. Given these aspects, the modelling approach using a higher roughness condition
is considered to be conservatively appropriate for this investigation.
Figure 2 – Greenhouse Internals
The existing case TUFLOW model was revised to include the increased roughness associated with the
greenhouse structure as well as the since constructed earthworks at the site (including bunds) to
represent the developed site conditions. The developed case model has been analysed for same
design events and used to quantify flood impacts associated with site development. Hydraulic results
are discussed in the following section of this report.
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2.4 Hydraulic Results
Hydraulic results for the existing and developed cases are attached in Appendix b and include flood
depth and velocity maps for the 10% AEP and 1% AEP design flood events. Additionally, flood impact
maps are also included in Appendix b for the roughness condition of n=0.07 as well as the sensitivity
analysis using n=0.1 as the difference between existing versus developed case flood levels at the site.
The following summary is provided on the flood impact results: ‐
The site is completely inundated during the 10% AEP and 1% AEP design flood events;
There is no fundamental change in hydraulic characteristics at the site including flood
magnitude, flood flow distribution, flood velocities or flood depths. This is primarily a result
of water being allowed to flow through the greenhouse structure during times of flooding
which fundamentally maintains existing flow characteristics and does not result in any re‐
distribution of flows;
Following initial model simulations and advice from Council, Bund 3 was moved to a location
between 5 m and 10 m to the north of the vegetation lining the creek immediately south of
the greenhouse. This was undertaken to ensure the maintenance of a riparian buffer in this
location.
The largest increases in flood levels were found to be limited to the site itself. The largest
increase in flood level was estimated to be up to 200mm immediately upstream from Bund 3.
This dissipated further upstream from the bund;
Flood impacts external to the site were found to be unsatisfactory with Bunds 1 and 2 in‐place
at the site. Accordingly, Bunds 1 and 2 should be removed from the site to otherwise minimise
flood impacts;
No flood impacts were found to occur on the western boundary of the property;
Minor flood impacts were found to occur to the adjacent property located to the south west
of the site (i.e. Lot 1 RP173884). The maximum increase in flood level was found to be up to
100mm in the 10% AEP event and 50mm in the 1% AEP event and does not impact on any
existing infrastructure or will compromise existing access provisions to and from the property.
As the topography rises steeply from Six Mike Creek in this area, the increases will have a
negligible impact in terms of the flood extent which fundamentally will not change. As such,
it is contended that these impacts are non‐worsening and will not result in actionable
nuisance;
Minor flood impacts are also found to occur to the southern lot on Lot 2 SP108094. This site
is used for industrial brick and paver manufacture by PGH Bricks and Pavers. The impacts to
this site are very marginal and are limited to a very small area adjacent to the site boundary.
Impacts were estimated to be up to 25mm for both the 10% AEP and 1% AEP flood events and
again will have a negligible impact in terms of the flood extent which fundamentally will not
change. It is also contended that these impacts are non‐worsening and will not result in
actionable nuisance;
Minor impacts were also estimated to occur to Lot 8 RP901387. These impacts were very
isolated and were less than 25mm in the 10% AEP event and below 10mm in the 1% AEP event
and are considered inconsequential, with no impact to any existing infrastructure or access
provisions;
The increased roughness sensitivity scenario using n=0.1 showed a very similar result and was
not significantly different to the n=0.07 case. The extent over which flood impacts occurred
were greater but were limited in magnitude to be very similar to the n=0.07 case. Flood
impacts external to the site were therefore found to not be adversely affected by an increase
in floodplain roughness; and
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It is expected that flood impacts external to the site will be lower than those reported owing
to the very conservative roughness condition of n=0.07 applied for the greenhouse. Flood
impacts are expected to be significantly reduced in the event that an n=0.05 condition is used,
which is more likely to be appropriate in this instance.
2.5 Conclusions and Recommendations
2.5.1 Summary of Findings
The following key findings are made: ‐
Some minor flood impacts were found to occur in areas external to the site, with the largest
increases estimated to occur in the 10% AEP design event. Impacts were found to be limited
to a maximum of 50mm in the 1% AEP event. Flood impacts were found to not impact on any
existing infrastructure, compromise any access provisions or result in a reduction in usable
land. It is contended that these impacts are non‐worsening and will not result in any
actionable nuisance;
There were no fundamental changes in flood impacts at the site under the sensitivity case
using a higher roughness of n=0.1 for the greenhouse. Flood impacts external to the site were
therefore found to not be adversely affected by an increase in floodplain roughness; and
It is expected that flood impacts external to the site will be lower than those reported owing
to the very conservative roughness condition of n=0.07 applied for the greenhouse. Flood
impacts are expected to be significantly reduced in the event that an n=0.05 condition is used,
which is more likely to be appropriate in this instance.
2.5.2 Recommendations
Based on an assessment of existing and post‐developed conditions outlined in the sections above, and
with consideration of the resulting flood impacts at the site, the following recommendations are
made: ‐
1. The greenhouse structure is to be fitted with lay‐down wall sheeting to the perimeter of the
greenhouse. The lay‐down walls should be extended to a minimum height of 1.7m to facilitate
flood waters flowing through the greenhouse during periods of severe flooding. The lay‐down
wall sheeting should be configured to automatically drop down based on hydraulic head alone
and in the absence of any mechanical or electrical systems which are prone to failure during
flood events. It is considered that a simplistic and readily fail‐safe arrangement involving the
lower wall sections being attached via Velcro strapping or similar to be appropriate in this
instance.
2. Bunds 1 and 2 currently constructed at the site should be removed to minimise flood impacts
external from the site. The current Bund 3 can be retained given that the flood impacts from
this bund were primarily limited to the site, with external impacts estimated to be minor and
of little consequence.
3. Following advice from Council, it is recommended that Bund 3 be moved to a location
between 5 m and 10 m to the north of the vegetation lining the creek immediately south of
the greenhouse to ensure the maintenance of a riparian buffer in this location.
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3. FLOOD MANAGEMENT PLAN
3.1 Introduction
The hydraulic model results outlined in the previous section of this report provide the framework for
consideration of site flood risks generally and the subsequent development of a site Flood
Management Plan (FMP). This section of the report aims to provide management and staff of the
business located at the site with detailed knowledge of flooding in the area and a concise framework
for training staff on procedures to be instigated at the site should flooding be likely to occur due to
heavy rainfall being experienced in the catchment.
The principal aim of this FMP is to ensure that any risk from flooding to people and property at the
site is appropriately managed, cognate of the site operations and results in a low and manageable risk.
The strategy to achieve this is full evacuation of the site prior to the site being flooded to a level where
it is unsafe to do so.
3.2 Operational Details
The site is operated as an agricultural development that includes fruit and vegetable growing. The
client has advised of the following summary in relation to site operations: ‐
The number of people on site is at a maximum of between 22 and 25 people, including staff
and management. Maximum site occupation occurs spasmodically throughout the year in
accordance with the timing of fruit and vegetable harvest periods.
There is no permanent occupation on the site. There is no overnight accommodation provided
at the site.
The hours of site operation are between 6.30am to 3.30pm Monday to Friday, and between
7am to 12am Saturday. There is no regular work conducted outside these operational times.
Employees typically drive to the site and park on‐site in informal car parking areas.
Equipment used on the site includes an electric forklift, tractor, lawn mower and brushcutter.
There are chemicals located at the site which are associated with agricultural uses for fruit
and vegetable growing.
3.3 Flood Risks
3.3.1 General Site Flood Risks
The general flood risks identified at the site and associated with this development include: ‐
The risk to people’s safety;
The risk of damage to property;
The operational risks (downtime) to the business; and
Environmental risks associated with potential contamination from chemicals.
In the event of wide‐scale flooding of the Six Mile Creek Catchment, these manifest via:
a) Inundation of the premises – causing risk to people, property and the environment, including
closure of the business; and
b) Inundation of the road network – causing risk to people and disruption of the business
operations.
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There are also ancillary risks to people, property, environment and operations that can occur
coincident with flooding, including: ‐
c) Storm damage of the premises and property. These can result in torn roofs, shattered
windows, damage from fallen trees, etc.
d) Loss of power.
e) Contaminated water supplies or sewage surcharge.
f) Constrained access/egress through intense rainfall, winds, fallen trees, debris, fallen
powerlines and surcharged manholes (displaced manhole covers) etc.
Items a) and b) are the principal causes of risk that are managed as part of this FMP.
Items c) to f) may or may not occur coincident with flooding and can occur to any property regardless
of whether they are within a floodplain. However, the FMP does also give due consideration to these
items which are risks that can hinder the proper execution of the FMP.
3.3.2 Flooding at the Site
As indicated in the sections above, the site is located on low‐lying land and is almost completely
inundated during the 10% AEP and 1% AEP flood events. Flood depths during the 1% AEP event are
in excess of 1.8m in isolated areas of the site. Given the flood depths at the site, and in associated
flood velocities that occur as estimated using the hydraulic modelling, this presents a serious risk to
both people, property and the environment at the site.
3.3.3 Access to Site
Current access to the site is via an entry point situated on Lake McDonald Drive as illustrated in Figure
1 previously. As part of the development, an alternative site access point has been secured to Lake
Macdonald Drive to the south and through the existing PGH Bricks and Pavers site located on Lot 2
SP108094 via an access easement. This new access will represent the primary access point to the site,
with the current access used as an alternative and secondary access location.
Both site entrances lead to an internal access road which traverses a small creek anabranch of Six Mile
Creek via existing low‐level crossings. As outlined in the flood modelling results, Lake McDonald Drive
in the vicinity of the site is generally immune from inundation during the 1% AEP flood event.
However, the internal access roads are susceptible to inundation during more frequent events and
will restrict site egress during times of flooding.
3.4 Management of Hazardous Materials and Chemicals
Potentially hazardous materials and chemicals are stored on site. In the event of a severe flood at the
site, all potential sources of contamination including hazardous materials and chemicals, as well as
waste bins and skips can either be: ‐
Removed from the site and taken to an area that is located well above the 1% AEP flood event.
This could include the area of the site associated with the secondary site access which is flood
free; or
Placed on a flood resilient building or enclose and raised to above the 1% AEP flood level.
It is considered preferable that the latter option is employed as this minimises the potential for
hazardous materials to be inadvertently left at the site during flood events or associated logistical
issues with physically removing such materials to the flood free area of the site during times of
flooding. Hazardous materials are to be stored in the buildings on site at a height above the 1% AEP
flood level (typically higher than 1.5 m above ground level) or in the vicinity of the existing site
entrance area providing security measures are in place.
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Como Glasshouse P/L C/‐ Martoo Consulting P/L Flood Impact Assessment – 305 Lake McDonald Drive Cooroy Following a flood event, it is possible that plastic sheeting and planting material may be deposited in the creek. Preventative measures such as removal of sheeting or raising the sides of the greenhouse structure prior to the arrival of floodwaters should be implemented. Similarly, an extensive inspection of the creek will be undertaken following a flood event to ensure the removal of any plastic sheeting and planting materials. 3.5 Flood Emergency Management Strategy 3.5.1 Method Given that the site is only occupied in daylight hours from Monday to Saturday, the best course of action to minimise site flood risk is to completely evacuate the site to higher ground at the PGH Bricks and Pavers site located adjacent to the primary site access location. An alternative for evacuation to higher ground is also available via the secondary access location. Like any planning for a potentially high risk event such as fire, earthquakes, etc. a FMP will require the following key requirements to be met to ensure the FMP is safe and effective: ‐ a) Training Education and Awareness is mandatory for all site personnel to ensure the effective implementation of this FMP. It will be important to distinguish regional flooding (long duration rainfall causing Six Mile Creek to rise moderately) from severe storms of short burst where the site may be inundated for short durations until the local stormwater runoff is able to discharge off the site. It may be more dangerous to be outside during a short duration storm event given wind and rain‐driven hazards that can occur. b) Site Refuge and Evacuation For short duration storms, staying on the site and under cover is generally the safest option. For long duration intense rainfall, the Flood Management Plan outlined in this section provides guidance on leaving the site and securing equipment and chemicals stored on site. Government agencies broadcasting flood warning messages will be used to assist in management of the site flood risks and providing guidance on whether the rainfall is localised or regional. Site flood triggers (as outlined below) will also provide site specific flood information which will inform this FMP. 3.5.2 Flood Triggers There are no water level gauging stations in close proximity to the site. Given the short response time of Six Mile Creek (i.e. understood to be less than 6 hours), evacuation procedures will be based on visual inspection of water levels in Six Mile Creek at one (1) location at the site. This location is identified as Location 1 in Appendix C. The hydraulic model results indicate that, during a significant flood event, once water breaches the top of the existing creek embankment at Location 1, there is up to two (2) hours until egress of the local site access road linking to the primary access to Lake Macdonald Drive is compromised. Even if the rate of rise is significant at Location 1, and the available warning is reduced, there is still adequate time available based on the flood modelling for on‐site personnel to safely and immediately evacuate the site. Accordingly, it is recommended that a water level gauge be installed in Six Mile Creek at Location 1 as illustrated in Appendix C. This site based gauge is to be continually monitored during periods of heavy rainfall. Once water levels at Location 1 reach a height of 92.0m AHD, the immediate evacuation of the site must be undertaken. This gauge could also be connected to a water level trigger and solar panel array to provide an audible warning for immediate commencement of site evacuation. Automation of this gauge should be considered by the site manager, and especially if the Location 1 is unable to provide visual reference for the site operations area. 3917‐01 / R01 v02 ‐ 31/08/2015 11
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3.6 Flood Refuge
Given the widespread inundation of the site in moderate to severe flood events, including associated
water depths and flow velocities, the complete evacuation of the site is the preferred management
method. The depth of inundation across the site indicates that directing employees and persons to a
dedicated refuge area on the site would result in an unacceptable risk during flood events. As such, it
is recommended that employees and persons on site be evacuated to the nominated emergency
evacuation location illustrated in Appendix C. This location is located to above the 1% AEP flood event,
provides employees and persons on site with a safe emergency refuge point as well as the ability to
reach Lake MacDonald Road. Employees are to remain at the refuge site until it is deemed safe by the
relevant authorities and/or site manager to return to either the site or their homes.
Consideration has been made regarding developing a refuge area on site. This would take the form of
an area of land raised above the 1% AEP design event flood level. This poses two risks, namely:‐
1. Potential flood impacts caused by the placement of the refuge area in the floodplain; and
2. Potential risk to employees and persons on site should a flood event greater than a 1% AEP design
event occur.
A refuge area on the site may prove beneficial during smaller events but should an event larger than
a 1% AEP design event occur, employees and persons on site will effectively be trapped and at risk of
rising floodwaters. As such, ensuring staff and persons are evacuated from the site as per the
procedures outlined below is considerably safer than remaining on an elevated pad within the
floodplain. Flood events typically occur very quickly in the vicinity of the site and the installation of a
water level gauge and the flood management procedures, outlined below, will provide site
management staff with adequate information regarding approaching flood events.
3.6.1 Procedures
Following are the procedures of the FMP. They are dependent on the conditions being experienced
at the time as well as the time of the day. There are three (3) general times of the day that will govern
the decision making process as follows: ‐
1. Before Opening (i.e. does the site remain closed and are employees notified?);
2. During normal Operation of the site; and
3. After Closing (i.e. secure the premises and make safe in case of flood, notify employees about
the following day).
Reference to these conditions and times will be made to facilitate the decision making process
discussed in each of the procedures.
Outside of opening hours
Outside of opening hours, the procedure for flood management is to notify employees to remain at
home and to not try and gain access to the site.
During opening hours
During opening hours and when employees and people are on site, the following procedures are to
be undertaken:‐
1. Site manager to remain vigilant and to obtain information from the relevant authorities (see
Table 3‐1) regarding the severity of rainfall.
2. If localised flooding is imminent, the site manager is to observe the low‐level crossing to the
south of the site (i.e. located just south of Location 1 as shown in Appendix C).
3. If the low‐level crossing becomes inundated, the site manager is to: ‐
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a. Instruct employees to make the site safe and secure (i.e. remove equipment and
chemicals to the refuge site);
b. Evacuate all non‐essential staff from the site; and
c. For essential site staff, congregate to a pre‐determined site area and await further
instruction from the site manager. Preparations for the immediate evacuation of
essential staff is to occur at this point.
N.B. Based on the hydraulic modelling results, it is estimated that there will be up to
approximately 2 hours of available warning time between the start of inundation of the low‐
level crossing and the inundation of the main egress route from the site.
4. Following the inundation of the low‐level crossing, the site manager is to continually inspect
and monitor the water level gauge installed at Location 1 (refer Appendix C).
5. Once the water level at the gauge reaches 92.0m AHD (and/or the audible warning is sounded),
the site manager is to immediately evacuate the remaining site personnel. All remaining
personnel at the site are to immediately make their way to the refuge location as illustrated in
Appendix C.
6. Once all employees and persons on site have been accounted for, the site manager is to notify
the SES and/or emergency response authorities to inform them that the site has been
evacuated.
7. The site manager is responsible for allowing employees to re‐enter the site following a flood
event. Considerations by the site manager in making this decision includes: ‐
a. Cessation of rainfall in the greater area;
b. Flood levels in Six Mile Creek decreasing to well below trigger levels (and in the
absence of further rainfall in the Six Mile Creek catchment);
c. Current flood and rainfall warnings as issued by any local agency and organisation;
d. Essential staff required and likely tasks to be performed, etc;
e. General safety of site (site access free of debris and flowing water).
After Closing
No persons will be at the site at this time. The site should be secured. Procedure is the same as for
outside operating hours as outlined above.
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3.7 Flood Monitoring and Emergency Services Contacts
Following is a list of all contact numbers to call for flooding advice on evacuation.
Table 3‐1 Contact Details and Information
Agency/Service Details
Local ABC Radio Station FM 90.3 or FM 95.3
Bureau of Meteorology 1900 955 360 Main Directory
1300 659 216 Flood Warnings
Noosa Shire Council (07) 5329 6500
State Emergency Service 132 500
Emergency Response 000
Queensland Government Traffic and Travel
13 19 40
Information Service
Sunshine Coast Council – Note 1 (07) 5475 7272 or 1300 007 272
(N.B. ‐ The Disaster Hub provides helpful http://disaster.sunshinecoast.qld.gov.au/
information in being prepared for and
informed during a disaster event).
Notes
1. Although the site is not located within the Sunshine Coast Council (SCC) administration area, SCC do
provide flood warning related information via the disaster hub that covers the upstream reaches of the
Cooroy Catchment as well as road conditions on the Bruce Highway. As such, this is a further source of
flood warning and advice information applicable to the site.
4. CERTIFICATION
For and on behalf of
Water Technology Pty Ltd
Alister Daly
Principal Engineer
RPEQ 7118
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Como Glasshouse P/L C/‐ Martoo Consulting P/L Flood Impact Assessment – 305 Lake McDonald Drive Cooroy APPENDIX A SITE LAYOUT PLAN 3917‐01 / R01 v02 ‐ 31/08/2015
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Legend
Road
Bund
Existing Buildings
Site
Cadastre
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development
Date: 2015-07-01T15:06:46
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Site Layout
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Como Glasshouse P/L C/‐ Martoo Consulting P/L Flood Impact Assessment – 305 Lake McDonald Drive Cooroy APPENDIX B HYDRAULIC MODEL RESULTS 3917‐01 / R01 v02 ‐ 31/08/2015
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Legend
Velocity Vectors - 10% AEP
Site
Cadastre
Depth - 10% AEP
< 0.5
0.5 - 1.0
1.0 - 1.5
1.5 - 2.0
2.0 - 4.0
> 4.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Existing Case
Date: 2015-07-01T11:56:51
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10% AEP Flood Depth
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Legend
Velocity Vectors - 1% AEP
Site
Cadastre
Depth - 1% AEP
< 0.5
0.5 - 1.0
1.0 - 1.5
1.5 - 2.0
2.0 - 4.0
> 4.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Existing Case
Date: 2015-07-01T11:57:05
Water Technology Pty Ltd 1% AEP Flood Depth
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Legend
Velocity Vectors - 10% AEP
Site
Cadastre
Velocity - 10% AEP
< 0.1
0.1 - 0.3
0.3 - 0.5
0.5 - 1.0
1.0 - 2.0
2.0 - 5.0
> 5.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Existing Case
Date: 2015-07-01T11:57:27
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10% AEP Flood Velocity
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Legend
Velocity Vectors - 1% AEP
Site
Cadastre
Velocity - 1% AEP
< 0.1
0.1 - 0.3
0.3 - 0.5
0.5 - 1.0
1.0 - 2.0
2.0 - 5.0
> 5.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Existing Case
Date: 2015-07-01T11:57:39
Water Technology Pty Ltd 1% AEP Flood Velocity
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Legend
Velocity Vectors - 10% AEP
Bund
Existing Buildings
Site
Cadastre
Depth - 10% AEP (m)
< 0.5
0.5 - 1.0
1.0 - 1.5
1.5 - 2.0
2.0 - 4.0
> 4.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case
Date: 2015-08-28T14:33:12
Water Technology Pty Ltd
10% AEP Flood Depth
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Legend
Velocity Vectors - 10% AEP
Bund
Existing Buildings
Site
Cadastre
Depth - 10% AEP (m)
< 0.5
0.5 - 1.0
1.0 - 1.5
1.5 - 2.0
2.0 - 4.0
> 4.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case
Date: 2015-08-28T14:41:01
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1% AEP Flood Depth
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Legend
Velocity Vectors - 10% AEP
Bund
Existing Buildings
Site
Cadastre
Velocity - 10% AEP (m/s)
< 0.1
0.1 - 0.3
0.3 - 0.5
0.5 - 1.0
1.0 - 2.0
2.0 - 5.0
> 5.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case
Date: 2015-08-28T14:39:29
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10% AEP Flood Velocity
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Legend
Velocity Vectors - 10% AEP
Bund
Existing Buildings
Site
Cadastre
Velocity - 10% AEP (m/s)
< 0.1
0.1 - 0.3
0.3 - 0.5
0.5 - 1.0
1.0 - 2.0
2.0 - 5.0
> 5.0
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case
Date: 2015-08-28T14:42:07
Water Technology Pty Ltd
1% AEP Flood Velocity
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Legend _ 3 Bund (J Existing Buildings C3 Site [_] Cadastre Afflux (m) - 10% AEP Gl < -0.200 HS -0.200 - -0.100 HJ -0.100 - -0.050 (5) -0.050 - -0.025 [J -0.025 - -0.010 L__] -0.010 - -0.005 [_] -0.005 - 0.005 [_] 0.005 - 0.010 [_] 0.010- 0.025 [] 0.025 - 0.050 [) 0.050 - 0.100 HE 0.100 - 0.200 Gl > 0.100 * 0 «50 100 150 200 Metres i i Scale: 1:5,000 @A3 ~ ww Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case LS Date: 2015-08-25T10:01:32 5 =! Water Technology Pty Ltd i v 7 AEP Flood Taal ex=Teis
Page 28
Legend _ 3 Bund (J Existing Buildings C3 Site [_] Cadastre Afflux (m) - 10% AEP Gl < -0.200 HS -0.200 - -0.100 HJ -0.100 - -0.050 (5) -0.050 - -0.025 [J -0.025 - -0.010 L__] -0.010 - -0.005 [_] -0.005 - 0.005 [_] 0.005 - 0.010 [_] 0.010- 0.025 [] 0.025 - 0.050 [) 0.050 - 0.100 HE 0.100 - 0.200 Gl > 0.100 * 0 «50 100 150 200 Metres i i Scale: 1:5,000 @A3 ~ ww Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case LS Date: 2015-08-25T09:56:06 5 =! Water Technology Pty Ltd i 7 AEP Flood Taal ex=Teis
Page 29
Legend _ 3 Bund (J Existing Buildings C3 Site L_] Cadastre Afflux (m) - 10% AEP MH < -0.200 HS -0.200 - -0.100 HJ -0.100 - -0.050 (MH) -0.050 - -0.025 [J -0.025 - -0.010 L__] -0.010 - -0.005 [_] -0.005 - 0.005 [_] 0.005 - 0.010 [_] 0.010- 0.025 [_] 0.025 - 0.050 [) 0.050 - 0.100 HN 0.100 - 0.200 Gl > 0.100 Scale: 1:5,000 @A3 ~ ww Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case Totes tocrrcony Pty td 10% AEP Flood Impact - Sensitivity Analysis (n=0.1)
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Legend _ 3 Bund (J Existing Buildings C3 Site L_] Cadastre Afflux (m) - 10% AEP Gl < -0.200 HS -0.200 - -0.100 HJ -0.100 - -0.050 (MH) -0.050 - -0.025 [J -0.025 - -0.010 L__] -0.010 - -0.005 [_] -0.005 - 0.005 [_] 0.005 - 0.010 [_] 0.010- 0.025 [_] 0.025 - 0.050 [) 0.050 - 0.100 HN 0.100 - 0.200 Gl > 0.100 Scale: 1:5,000 @A3 ~ ww Coordinates: GDA94 Zone 56 Cooroy Agriculture Development - Developed Case Totes tocrrcony Pty Ut 1% AEP Flood Impact - Sensitivity Analysis (n=0.1)
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Depth Gauges
Road
Evacuation Area
Bund
Existing Buildings
Site
Cadastre
0 50 100 150 200 Metres
Scale: 1:5,000 @A3
Coordinates: GDA94 Zone 56 Cooroy Agriculture Development
Date: 2015-07-01T16:31:10
Water Technology Pty Ltd
Emergcy Evacuation Plan