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Appendix F Engineering Report - 14-16 Mary Street, Noosaville - Bounce Hostels 15.6.2018
Attached to the e-mail Visitor Accommodation Type 4 Conventional - 122 beds (Engineering Report, Economic Study, Geotechnical Investigation, Flood Certificate, Accoustic Report, Management Plan) MCU18/0102.msg.
Appendix F – Engineering MATERIAL CHANGE OF USE TO ESTABLISH RESIDENTIAL USES - VISITOR ACCOMMODATION TYPE 4 CONVENTIONAL 14-16 Mary Street, NOOSAVILLE described as Lots 3 & 4 on RP 122928 Applicant: Bounce Hostel Noosa Pty Ltd ATF The Bounce Hostel Unit Trust Date: 15th June 2018 Unit 5, 100 Pickering Street, Enoggera 1
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ENGINEERING REPORT
Address: 14-16 Mary Street, Noosaville
Applicant/Client: Bounce Hostels
1. Background
Tod Consulting have been engaged to provide technical advice on the impacts of a proposed
development at 14-16 Mary Street, Noosaville (Lot 3&4 RP 122928). The property is within the flood
hazard zone and within the Acid Sulphate Soils overlay area
The site is also traversed by a 450mm diameter truck sewer located approximately 13m from the rear
boundary. The site currently contains an existing building that is used for retail purposes. The building
is surrounded by hardstand areas (a combination of compacted gravel and concrete pavements).
A prelodgement meeting was held with Noosa Council in October 2017. At this meeting Council asked
that the following engineering issues be addressed with the Material Change of Use development
application:
• Flood – especially in regard to proposed basement car park
• Acid Sulphate Soils – Investigation and Management Plan
• Stormwater Management
• Access and car parking - particularly for service vehicles
• Any additional works or treatment in the vicinity of the trunk sewer including advice from
Unitywater
The purpose of this report is to address the above issues and provide likely engineering solutions for
each.
2. Flood impacts and protection of the basement car park
A food certificate for the site has been obtained and it confirms that the defined flood level for the site
is RL2.4 AHD for a 1% AEP Under 2100 Climate Change Conditions. The current levels on the site vary
from RL 2.0 to RL 2.3 AHD. Preliminary Architectural drawings show proposed floor levels for the hostel
rooms and facilities at RL 2.7 to provide adequate free board above the defined flood level. The existing
kerb and channel invert levels in Mary Street at this location are between RL 1.6 and 1.7 AHD with the
footpath level at RL 1.8 to 1.9 AHD.
To protect the basement car park from flooding it is proposed to install a proprietary automatic flood
barrier at the top for the ramp just inside the property boundary. There are several automatic flood gates
on the market that use the rising flood levels and the associated hydraulic differential to activate the
barrier and raise it to protect the car park from flood waters. They do not require power or human
intervention. The flood gate will be located between the perimeter retaining walls that will be used to lift
the site levels above the defined flood level. Refer architectural elevations and sections for further
details. The links below are two examples of the type of flood barrier proposed.
http://floodbreak.com
https://flowdefence.com.au/
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The access ramp to the basement carpark will be exposed to the weather and therefore run off from
the ramp will need to be collected and disposed of. It is proposed to install a grated drain at the base of
the ramp to collect runoff. This will be discharged into a sealed storage tank and pump below the
basement car park which would be set up to pump to the street during a rainfall event. It is necessary
to have a sealed collection tank instead of a soak away pit due to the groundwater levels for the site
being above the basement level. A soak away drain located at the basement level connected to the
grated drain would, at times, act in reverse and allow ground water into the basement. (Refer Geotech
report). The catchment area of the ramp is approximately 84m2, so a 2500 litre tank would also provide
emergency storage for the equivalent of a 30mm rainfall in the event of a power failure. In an extreme
event, coinciding with a power failure, the basement area would offer additional storage capacity. For
example, if 500mm of rain was to fall with power being off, the depth of water accumulating in the
basement would be only 53mm in depth. To put this in perspective, data from the Bureau of
Meteorology indicates that the maximum daily rainfall recorded at Tewantin was 310mm in August
2007 – refer attached. The grated drain, storage tank and pump system would also be able to dewater
the basement area once the power was restored. It should be noted that the storage tank and pump is
not required to keep flood waters out of the basement.
3. Acid Sulphate Investigation and Management
Please refer to the separate report prepared by Core Consultants.
4. Stormwater Management
4.1. Existing network and legal point of discharge
Stormwater from the site would need to be piped to the street and discharged to the kerb and channel
using kerb adaptors as there is no existing stormwater pits in front of the development site to connect
to. The nearest stormwater pit is located approximately 40m to the east. An inspection of this pit has
identified that the invert level is less than 1.0m below the road surface. Based on minimum allowable
pipe grades and sizes, and existing road levels there would insufficient cover if a pipe was extended
from this pit to the closest point in front of the development site. Note the existing kerb and channel
has a grade of less than 0.5% and falls both east and west from the area in front of the site. ie the site
is located at the crest of the road. The discharge from the site would therefore be split to the east and
west side of the building and discharged to the street at both sides of the property. The reception area
roof area could be separately piped directly to the kerb and channel. The number of discharge points
can be determined during the detailed design of the building hydraulic plans.
4.2. Stormwater Quantity
The existing building and concrete pavement areas on the site have a combined area of 875m2. In
addition to this there is over 1080m2 of unsealed compacted gravel hardstand parking area surrounding
the existing building – this is best viewed in the 2015 aerial photo. Refer marked up aerial plan below
showing these areas. Given the nature of this hardstand pavement we believe that, conservatively,
50% of this area can be included in the impervious area of the existing site. As such the total impervious
area for the existing site is effectively 1415m2. The proposed development includes buildings and
impervious (paved areas) totalling 1433m2. Note the drying area on east side of building will be either
permeable paving or turfed. As there is only a minor increase in the impervious area we contend that
on-site detention is not necessary.
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17699 - Bounce Hostel, 16 Mary Street Noosaville – Engineering Report – Rev A
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Existing Roof and Paved areas
Existing Gravel Hardstand areas
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4.3. Stormwater Quality
Under the State Planning Policy – Water, the assessment benchmark for water quality treatment states
that treatment of stormwater is required only if a material change of use application involves premises
greater than 2,500m2. As the development is on a land area of 2293m2, the requirement for stormwater
quality treatment is therefore not triggered. Notwithstanding, it has been suggested by Council officers
that Division 20 of the Noosa Plan — Water Sensitive Design Code, which outlines water quality
objectives, needs to be addressed and in particular objective items O1, O7 and O10. Extracts from
these codes follow:
column 1 Specific Outcomes column 2 Probable solutions
Maintenance of environmental values S1.1 Development meets the applicable
and water quality objectives performance outcomes of the State Planning
O1- Downstream ecosystems, properties Policy Appendix 2 SPP Code: Water Quality; AND
and infrastructure are not adversely S1.2 Design and construction methods for
impacted by either changes to flow, water stormwater quality treatment assets are in
quality or ecosystem health caused by accordance with Healthy Waterways Water By
development. Design Guidelines; AND
S1.3 Commitments are made to implement a
cost effective maintenance strategy for the life
cycle of any engineered water quality treatment
device; AND
S1.4 Water quality nutrient load modelling is
undertaken in accordance with Water by Design
Music Modelling Guidelines to demonstrate
compliance with the SPP nutrient reduction
requirements; AND
S1.5 Stormwater outlets that directly discharge
to naturally acidic environments are managed to
prevent eutrophication; AND
S1.6 Suitable methods are incorporated to
prevent the spread of invasive environmental
weed species at stormwater outlets.
O7 Natural treatment strategies, including S7.1 No probable solution
grass swales and bio-retention systems,
vegetated filtration strips and gross pollutant
traps, are used wherever possible.
O10 Development design and operation S10.1 Methods to prevent gross pollutants
facilitates nil increase in gross pollutants entering stormwater systems and waterways
entering stormwater systems. are adopted that— a) are low maintenance; b)
prevent nutrient leaching in the event scheduled
maintenance is delayed; and c) facilitate human
behaviour change (e.g. signage, bins)
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With respect to Objective O1 the first item of the probable solutions states that development meets the
applicable performance outcomes of the state planning Policy. Given that the performance outcomes
under the SPP are not triggered by extension the remaining objectives within objective O1 should not
apply.
Objective O7 & O10 suggests natural treatment strategies are used wherever possible and that
methods should be implemented to reduce gross pollutants from entering the stormwater system. Given
the flat nature of the site and the road frontage, and the necessity to discharge stormwater to the kerb
and channel as outlined above, there is insufficient fall available to provide on site treatment by the way
of gross pollutant traps or bio-retention systems. In addition, to meet plumbing and building codes, roof
water cannot be discharged to the surface which eliminates the possibility of providing grass swales or
filtration strips. As noted above the existing site contains large areas of unsealed gravel pavement, the
run off from which flows across the site to the street frontage taking with it sediments from the gravel
surface. Roof water from the existing building also discharges onto the gravel surface at the rea of the
building. Photos below show evidence of gravel silt accumulating in the kerb and channel.
Notwithstanding the fact that treatment of stormwater is not triggered by the State Planning Policy, as
the development proposal includes landscaped areas covering in excess of 35% of the site and an
underground car park, which eliminates oils and grease mixing with stormwater, it is expected that the
quality of the run off from the site will improve compared to its current use.
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5. Car park and Service Vehicle access
The ramp to the basement car park is shown on architectural drawing DA.06 by Zest Building Design.
Tod consulting have checked the longitudinal grades and grade changes and confirm that the ramp
meets the requirements of AS2890.1.2004 and Council standard drawing IPWEAQ RS-50. The car
park layout shown on preliminary architectural drawing DA-03 provides car parking spaces that exceed
the requirements of AS2890.1 for a user class 2 car park.
Architectural Drawing DA01 by Zest shows the proposed service bay area on the eastern side of the
site fronting Mary Street. Attached is a swept path diagram showing proposed movements for a service
vehicle into and out of this space. Ref 17699-SK001. This diagram demonstrates that a service vehicle
can enter and exit the site in a forward motion.
6. Existing Sewer
As noted in the introduction a 450 diameter trunk sewer crosses the site approximately 13m from the
rear boundary. The sewer is currently 2.5 to 2.8m below existing surface levels but as a result of the
higher floor levels required (as noted in section 2) the sewer will ultimately be over 3.0m deep.
Discussions with Unitywater have confirmed that for a 3m deep sewer they require the proposed
buildings to be set back a minimum of 3m from the centreline of the sewer and founded below the zone
of influence. Architectural concept drawings have been amended to reflect this requirement. Structural
drawings will be prepared as part of the detailed design.
7. Conclusion
We believe that this report demonstrates that the engineering aspects of the proposed development
can be successfully and suitably managed, and as such we seek Councils support for the development
application.
Prepared by
Doug Reynolds (RPEQ 9072)
Tod Consulting Pty Ltd
28 March 2018
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17699 - Bounce Hostel, 16 Mary Street Noosaville – Engineering Report – Rev A
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Daily Rainfall (millimetres)
TEWANTIN RSL PARK
Station Number: 040908 · State: QLD · Opened: 1995 · Status: Open · Latitude: 26.39°S · Longitude: 153.04°E · Elevation: 6 m
Statistics for this station calculated over all years of data
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Mean 144.2 226.4 221.0 158.0 146.2 123.2 70.2 86.0 57.1 100.4 99.6 139.5
Median 122.4 162.6 170.6 131.6 126.5 105.1 61.4 31.3 29.2 69.2 85.0 129.6
Highest daily 181.2 252.0 188.8 161.2 152.0 83.8 94.0 310.2 85.0 232.6 135.0 99.4
Date of highest 10th 9th 15th 14th 20th 3rd 25th 24th 7th 9th 6th 10th
daily 2011 1999 2017 2009 1999 2012 1999 2007 2007 2010 1997 2004
1) Calculation of statistics
Summary statistics, other than the Highest and Lowest values, are only calculated
if there are at least 20 years of data available.
2) Gaps and missing data
Gaps may be caused by a damaged instrument, a temporary change to the site operation, or
due to the absence or illness of an observer.
3) Further information
http://www.bom.gov.au/climate/cdo/about/about-rain-data.shtml.
Product code: IDCJAC0009 reference: 36343374 Created on Wed 28 Mar 2018 11:36:27 AM EST
© Copyright Commonwealth of Australia 2018, Bureau of Meteorology.
Prepared using Climate Data Online, Bureau of Meteorology http://www.bom.gov.au/climate/data
Contact us using details on http://www.bom.gov.au/climate/how/contacts.shtml.
We have taken all due care but cannot provide any warranty nor accept any liability for this information.
http://www.bom.gov.au/other/copyright.shtml Page 2 of 2
Page 9
ENS
COLD ROOM
DRYING COURT
UP
TV
UP
ENS
CAFE
PANTRY
ENS
LIFT
DRY STORE
TV
AMBULANT
Travel Desk
UNISEX
UNISEX
PWD
1:14.5 Wheelchair Ramp Access
DRAINAGE POINT LOCKERS / LUGGAGE
UP
SETBACK
3M SIDE
DRIVEWAY CATCHMENT AREA RECEPTION
2000mm Accoustic Fence
STORE
Delivery Bay
SETBACK
3M SIDE
Down to basement
carpark
Bin Enclosure
Bunded
Turn Bay
FLOOD BARRIER - REFER TO DETAIL
PROPOSED CONCRETE FOOTPATH
PROPOSED CONCRETE PROPOSED CONCRETE
CROSSOVER TO CROSSOVER FOR
BASEMENT CARPARK DELIVERY BAY
M A R Y S T R E E T
J:\2017\17699SD1_Subdivision_14-16_Mary_Street_Noosaville\4.CADD\#ACAD\17699_SK001.dwg
0 1 2 3 4 5m
1:100 (A1) 1:200 (A3)
COPYRIGHT © Associated Consultants Client Drawn Verified Project Drawing Title Scale Sheet Size
This drawing is subject to NV DR
copyright in accordance with the FUQIANG Designed Verified
BOUNCE HOSTEL 14-16 MARY ST SERVICE VEHICLE AS SHOWN A1
agreement between Tod
Consulting pty ltd (tc) and tc's
client. This drawing shall only be
INVESTMENTS PTY LTD NV DR NOOSAVILLE QLD 4566 TURNING MANOEUVRE Drawing Number
Approved RPEQ No
used for this specific project.
D. REYNOLDS 9072 RDP 17699-SK001
This drawing shall not be used
Noosa: 07 5449 9600 LOCAL AUTHORITY
Sunshine Coast: 07 5329 3190 Mackay: 07 4840 2337
Signed MCU APPROVAL HORIZ DATUM 0 10 20 30 40 50 60 Sheet Revision
for construction until marked as PO Box 61, Noosaville, QLD 4566
A 28.03.18 ISSUED FOR APPROVAL NV ROL APPROVAL VERT DATUM
'issued for construction' in the
revision description. Rev Date Revision Description Drawn
[email protected] www.todconsulting.com
ABN 39 128 805 336
28.03.18 OPW APPROVAL RL DATUM MEASUREMENT BAR - INCREMENTS IN mm
1 of 1 A