Approved Documents

Page 2

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COUNTRY CLUB VILLAGES PTY LTD

STORMWATER INFILTRATION SYSTEM MAINTENANCE
PLAN
FOR

NOOSA DOMAIN RETIREMENT VILLAGE
WALTER HAY DRIVE, NOOSAVILLE

 

 

 

TABLE OF CONTENTS
1.0 INTRODUCTION ...... 0... ccc ete beeen renee nn ees 2
1A. ‘Stormwater Objectives wesicssysrscicsvavaeiwenanineecatauenenet 9 v1 oo wo 0 6 6 a o tnntcuraeenenetentwnie 2
2.0 EXPECTED INFILTRATION SYSTEM MAINTENANCE .................005- 3
2.1 Maintenance ACCESS ...... 00. eee nn eee nee e neta 3
2.2 Vegetation Management and Sediment Control! ........... cece e eee eens 3
23 ‘Litter Management's « y « « s secs: 6 sae 5 vo perenne oa oo ye rer wae oH ew mains 3
2.4 Infiltration System Infrastructure... 6.6. e ee 4
2.5 Health and Safety Issues .. 6.0 0... ce cee tee ete teens 4
2.6 Site Clearance and Restoration. 0.0.0... see ee sce ceee eer ec ene ee eens 4
3.0 MAINTENANCE COSTS 5c ecuscsscacc 22 per r ere memers REEHEEMRE Ee 4
4.0 ASSET OWNERSHIP. .ccccouincose gone on er onnienecnansew 8 89 FM SaLdialais Be ono FOR MRE 4
ENGINEERING DRAWINGS
Document Status
Preliminary O
Draft O
Final 4
Author _Andrew Fraser Signature AE—— Date 16/08/2006

 

COPYRIGHT © 2006 JF&P CONSULTING ENGINEERS PTY LTD
THIS DOCUMENT MAY NOT BE COPIED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS IN PART OR IN WHOLE
WITHOUT WRITTEN CONSENT OF JF&P CONSULTING ENGINEERS PTY LTD

 

Noosa Domain Retirement Village, Noosaville 4 Stormwater Infiltration System Maintenance Plan
M1717 Revision B 416 August, 2006

 

Page 3

eb

MAITENENCE PLAN
1.0 INTRODUCTION

This Maintenance Plan has been prepared specifically for the stormwater infiltration
system incorporated in the JF&P Consulting Engineers Pty Ltd civil engineering
stormwater drainage design for the Noosa Domain Retirement Village, Noosaville. The
infiltration system comprises a pipe network which contains a high percentage of 525mm
Nominal |.D FRC Slotted Pipes interconnected to 1800mm Nominai I.D RC pipes within
the network where required to detain some of the volume.

The infiltration system captures and treats stormwater runoff from roof downpipes and
surface flow through the principles of filtration. It does not rely on the use of vegetation or
above ground devices and is, therefore, an inherently low maintenance device. The
system also contains no standing water. It will not be subject to algal blooms or to
mosquito breeding.

All the fields inlets capturing surface runoff and directing flows into the infiltration system
will be fitted with ‘Ecosol’ baskets that will effectively capture and prevent gross pollutants
and course sediment from entering the system.

1.1 Stormwater Objectives

The following conditions for Stormwater Drainage were stated in the ‘Noosa Council IDAS
Development Application Decision Notice’ dated 21 December 2005.

1. All stormwater drainage from the site shall be collected on site and discharged
generally in accordance with Plan — Drainage Design 0379 SK 05B dated October
2004 prepared by Greg Gibbs Architects, so there is no net increase in stormwater
runoff from the site up to a Q100 event. Plans of the discharge design shall be
prepared by a Registered Professional Civil Engineer and submitted to Council prior
to obtaining a Development Permit for Operational Works.

2. Roof runoff from any new dwelling unit or apartment shall be directed to a rainwater
storage system or tank (minimum storage 1400 litres per dwelling unit (villa) and
1000 litres per serviced or non-serviced apartment) that is plumbed to service the
toilets in the new dwelling and landscaping areas. The design of the rainwater
storage system shall be to the satisfaction of the Manager Plumbing Services.

3. Overflows from rainwater tanks may be discharged into the gravel drains proposed.

4. An approved maintenance plan for the treatment system be incorporated in the
Management Scheme for the development and a copy of this shall be provided for
Council's records prior to commencement of the approved Use.

5. All site stormwater drainage shall be by means of a gravity system.

 

Noosa Domain Retirement Village, Noosaville 2 Stormwater Infiltration System Maintenance Plan
M1717 Revision B 16 August, 2006

Page 4

ebrepe

2.0 EXPECTED INFILTRATION SYSTEM MAINTENANCE
Maintenance of the infiltration system is expected to be limited to the following:

e Management of surface vegetation and blockage of the field inlets

e Removal of any accumulated litter including leaves, sediment and other debris from
the ‘Ecosol’ baskets

e Routine inspection of the underground system

2.1 Maintenance Access

Maintenance access to the system is available via the internal road network. Access to
the underground infiltration system can be gained via manholes located on each section
of the 1800mm dia RCP.

2.2 Vegetation Management and Sediment Control

On the surface surrounding field inlets, the requirement is to maintain a sparse vegetation
cover only — preferably well maintained turf. Additional planting should not be undertaken
in this area nor should topsoil or other material be added as these may cause blockage of
the inlets and blockage within the underground system.

The underground infiltration system has been designed to operate effectively with up to
50% blockage (sediment build-up and blockage) within the slotted pipe system. The
slotted pipe system should be cleaned when sediment build-up exceeds a quarter of the
capacity of the pipe. CCTV inspections of the underground infiltration system should be
undertaken every two years to assess the extent of sediment build up. All attempts should
be made to prevent sediment from entering the system.

2.3 Litter Management

Visible litter around the field inlet surface grates should be removed and disposed of.
Excessive accumulation of leaves and other vegetative matter should also be removed
regularly from the field inlet surface as this will reduce the efficiency of the infiltration
system.

Routine inspection and emptying of the ‘Ecosol’ baskets shall be undertaken.

In all litter removal and disposal operations, appropriate precautions should be taken
against hazardous objects.

Collected litter should be disposed of in an appropriate manner at Council's refuse tip.

 

Noosa Domain Retirement Village, Noosaville 3 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 5

abiPQp

2.4 Infiltration System Infrastructure

During each routine inspection, the following inspections of the infiltration system
infrastructure should be undertaken.

e Check integrity of all field inlets and baskets
e Check all concrete structures for damage or deterioration

2.5 Health and Safety Issues

Staff involved in management and maintenance activities within the infiltration system
should be cognisant of the health and safety issues associated with these activities.
Some of the relevant issues are the handling of litter and working in confined spaces if
access is required to the underground chamber. Hazards exist with maintenance
activities and the implementation of appropriate work practice guidelines for these
activities is recommended for the maintenance and management of the infiltration system.
2.6 Site Clearance and Restoration

The site should be left in a clean and tidy condition following maintenance work.

3.0 MAINTENANCE COSTS

Estimated resource requirements and maintenance costs for the work described above
follow:

 

 

 

Task Frequency | Resources Hourly Rate | Hours | Amount
Routine inspection, | 3 Months 2 x labour $90 8 $720
vegetation 1 x truck $80 8 $640
management,

weeding and litter

removal

CCTV 2 Years $3,500

 

 

 

 

 

 

 

4.0 Asset Ownership

The works shall remain in the ownership of the Retirement Village and maintained
accordingly.

 

Noosa Domain Retirement Village, Noosaville 4 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 6

afr CP

ENGINEERING DRAWINGS

 

Noosa Domain Retirement Village, Noosaville
M1717

5 Site Based Stormwater Management Plan
Revision B 16 August, 2006

Page 7

   

 

 

 

 

 

 

 

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Page 10

COUNTRY CLUB VILLAGES PTY LTD

SITE BASED STORMWATER MANAGEMENT PLAN
FOR

NOOSA DOMAIN RETIREMENT VILLAGE
WALTER HAY DRIVE, NOOSAVILLE

M1717
alrApE Revision B

16 August, 2006

Page 11

2D
COUNTRY CLUB VILLAGES PTY LTD
SITE BASED STORMWATER MANAGEMENT REPORT

FOR

NOOSA DOMAIN RETIREMENT VILLAGE
WALTER HAY DRIVE, NOOSAVILLE

 

TABLE OF CONTENTS
1.0 INTRODUCTION . 00.0.6. e nnn enna 2
4:4 Stormwater Objectives... .c ccc se ee eo reese sect cane wee eee enue 2
2.0 SITE GHARACTERISTICS: 5 « s « « « saunas 4 s ¢ seen ae so tern ye x oemeIS eae 3
QA. LOGALIOA ou eeu eu y memes eee ene ann yen cavtuenmsomaned HR GROVE STR RAN HS 3
2.2 Topography and Site Drainage... 6... cee eee 3
FIGURE 1 —SITE LOCATION PLAN 2... 0. ccc cece cere ee ee enn ene 4
3.0 PRE AND POST DEVELOPMENT STORMWATER DRAINAGE. .............. 5
3.1 Catchments... 0000... e eee n etree tte ee 5
3.2 Pre—Development FIOWS. ... 0.0.0... cece cee cece rere neta nn nnenee 6
3.3 Post= Development FIOWS . 6 ccc ccc cede edhe eee ee eee eee eee 56
FIGURE 2—PRE-DEVELOPMENT CATCHMENT PLAN...............-..-- 7
FIGURE 3 —POST-DEVELOPMENT CATCHMENT PLAN................... 8
FIGURE 4 —INFILTRATION DETAILS ..... 0.0.6. eee 9
4.0 XP — SWMM MODE bin: aes = a = x 2 o seers 48 2 8 x Ga yen nv 0 ow on oni 10
A, MOAUCHORN: .ooe, nce;  omenthnotinitnG OE EE REY EEE 2) 2 BS ROMCROUWONIOE BER AR aR AR SE 10
4.2 Catchments .......00.0 000000 tee 10
WS POWs pe Gee eNO CRINKLE 10
4A Ress csyeuscesgengyee eg eee eter eee SKE SULT GOVE Eee ITH eNO ee 10
FIGURE 5— XP-SWMM RESULTS .............. 000.0 c eee 11
5.0 CONCLUSION 2.2... b eens 12

APPENDIX A — RAINFALL INTENSITIES

 

 

Document Status
Preliminary
Draft
Final

Author _Andrew Fraser Signature Ag KR Date 16/08/2006

SOO

 

COPYRIGHT © 2006 JF&P CONSULTING ENGINEERS PTY LTD
THIS DOCUMENT MAY NOT BE COPIED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS IN PART OR IN WHOLE
WITHOUT WRITTEN CONSENT OF JF&P CONSULTING ENGINEERS PTY LTD

 

Noosa Domain Retirement Village, Noosaville 1 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

 

Page 12

abo

1.0 INTRODUCTION

JF&P Consulting Engineers Pty Ltd have been commissioned by Country Club Villages
Pty Ltd to compile a Site Based Stormwater Management Plan for the site located at Lot
2 SP 162077 Walter Hay Drive, Noosaville. It is proposed to construct a Retirement
Village consisting of 169 Dwellings / Accommodation Units and Ancillary Facilities.

The purpose of this study is to investigate the effects of the development proposal on the
stormwater drainage characteristics of the site.

Roof-water runoff from all dwellings is to be directed into rainwater storage systems as
required in Condition 54 of the Noosa Council IDAS Development Application Notice
dated 21" December 2005 and forms an integral component of the overall stormwater
drainage strategy for the site.

Preliminary drainage design calculations were undertaken by Robson & Associates Pty
Ltd and documented on Greg Gibbs Architects drawing number 0379 SK 06B. These
calculations have now been superseded by the current JF&P drainage design.

1.1 Stormwater Objectives

The following conditions for Stormwater Drainage were stated in the ‘Noosa Council IDAS
Development Application Decision Notice’ dated 21 December 2005.

1. All stormwater drainage from the site shall be collected on site and discharged
generally in accordance with Plan — Drainage Design 0379 SK 05B dated October
2004 prepared by Greg Gibbs Architects, so there is no net increase in stormwater
runoff from the site up to a Q100 event. Plans of the discharge design shall be
prepared by a Registered Professional Civil Engineer and submitted to Council prior
to obtaining a Development Permit for Operational Works.

2. Roof runoff from any new dwelling unit or apartment shall be directed to a rainwater
storage system or tank (minimum storage 1400 litres per dwelling unit (villa) and
1000 litres per serviced or non-serviced apartment) that is plumbed to service the
toilets in the new dwelling and landscaping areas. The design of the rainwater
storage system shall be to the satisfaction of the Manager Plumbing Services.

3. Overflows from rainwater tanks may be discharged into the gravel drains proposed.

4. An approved maintenance plan for the treatment system be incorporated in the
Management Scheme for the development and a copy of this shall be provided for
Council’s records prior to commencement of the approved Use.

5. All site stormwater drainage shall be by means of a gravity system.

 

Noosa Domain Retirement Village, Noosaville 2 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 13

abreoe

2.0 SITE CHARACTERISTICS
2.1. Location

The subject site is located on the corner of Walter Hay Drive and Eenie Creek Road,
Noosaville. The site area is approximately 5.69ha and is bounded by Walter Hay Drive to
the west, Eenie Creek Road to the south and un-made Road to the north and east. A Site
Location Plan can be seen on Figure 1.

2.2 Topography and Site Drainage

The existing site is relatively flat with all runoff draining into melaleuca swamp before
discharging via ground water into Noosa Waters.

The site was stripped to a level of approximately RL 1.0m AHD. A sand layer was then
placed onto the site to an approximate level of RL 2.5m AHD. It is proposed that all site
runoff captured and directed into the designed infiltration system will infiltrate through this
1.5m sand layer and discharge downstream into the existing melaleuca swamp. The
infiltration and discharge downstream will assist in maintaining the natural characteristics
of the melaleuca swamp.

 

Noosa Domain Retirement Village, Noosaville 3 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 14

 

Naa

Proposed
Business

Centre

Site Location

      
   
   
   

FIGURE 1
SITE LOCATION PLAN

 

Noosa Domain Retirement Village, Noosaville
M1717

4
Revision B

Site Based Stormwater Management Plan
16 August, 2006

Page 15

3.0 PRE & POST DEVELOPMENT STORMWATER DRAINAGE

The Rational Method Formula was used to calculate the stormwater runoff flows through
and off the site for the Pre-Development 100 year ARI event. The Rational Method
formula is as follows.

Q=C1A/360

Where Q = Peak Flow Rate (m*/s)
C = Runoff Co-efficient
A = Area of Catchment (ha)
{ = Rainfall Intensity (mm/hr)

3.1 Catchments

The catchment in the pre-developed scenario is based on the natural contours as
opposed to the developed scenario where the catchments are divided to suit the
proposed development flow characteristics. The catchment areas are shown in Figure 2
and Figure 3 for the pre-developed scenario and post-developed scenario respectively.

3.2 Pre — Development Flows

The catchment area for the pre-development scenario is 5.46ha, refer Figure 2. For the
purpose of this scenario the catchment is assumed to be open space/parks and hence
from Table 5.04.1 in QUDM (Queensland Urban Drainage Manual) a value of 0.00 was
adopted for the Fraction Impervious.

For the pre-development scenario the site topography is relatively flat and therefore a time
of concentration of 15 minutes was adopted from Table 5.05.1 in QUDM. A Table of the
Rainfall Intensities assumed for the proposed development site are shown in Appendix A.

Table 1 Catchment Parameters — Pre-Development Scenario

 

 

 

Catchment | Area | Fract.| t, I Cio | Croo | Qtoo

Scenario (ha) | Imp. | (mins) | (mm/hr) (m’/s)
Pre-

Development 5.46 | 0.00 15 212 0.70 0.84 2.70

 

 

 

 

 

 

 

 

 

3.3. Post - Development Flows

The stormwater system adopted for the proposed site includes an underground
stormwater pipe network with 3 outlets to the north and north-western boundaries. It also
includes an underground infiltration system consisting of perforated FRC pipes collecting
Qzo roofwater runoff and infiltrating this into a sand layer located at approximately RL
1.0m AHD to RL 2.5m AHD before being discharged into an existing melaleuca swamp
located downstream. The underground infiltration system is not connected to the
underground stormwater system. Therefore, all runoff captured in the infiltration system
will be infiltrated and treated via the sand layer. There are also various points where
overland flow will be discharged from the site.

The proposed development site was modelled using the computer modelling program XP
- SWMM. The model includes both an underground pipe network and a surface network

 

Noosa Domain Retirement Village, Noosaville 5 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 16

2D

of roads and swales. Details of this model can be found in Section 4.0.

To detain the Qzy flow from the roofwater runoff it has been proposed to construct a pipe
network which contains 450mm and 525mm Nominal |.D FRC Slotted Pipes. Refer to
Figure 4 to view the proposed locations of the 450mm and 525mm slotted pipes.

The Infiltration System has been designed to contain and infiltrate the Qa roofwater
runoff. Due to the fact that the infiltration system is only containing the Qzo flows from the
roof, the XP-SWMM model has allowed for the remaining roof flow (Q100 — Qzo) to be
taken by either the stormwater pipe system or via overland flow. The Infiltration system
will also act as a water quality system with all runoff collected in the infiltration system
being treated through the sand layer before being discharged downstream in the
melaleuca swamp.

The following Table shows the required length of 450mm and 525mm Nominal |.D FRC
Slotted Pipes required to detain the volume of roofwater runoff for the 20 year ARI storm
event. Details of Infiltration sub-catchments can be found on Figure 4.

Table 2 _ Pipe Lengths required for storage and infiltration.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sub - 450 mm or | Number of | Length of | Available Required
Catchment| 525mm pipes Pipe Volume of Volume of
FRC Pipe (m) Storage (m’) Storage (m’)

1 450 3 24 12 12

2 450 3 24 12 12

3 450 3 24 12 12

4 450 3 12 6 6

5 525 2 16 7 6

6 525 1 92 21 21

7 525 2 16 7 6

8 450 2 20 7 6

9 525 1 40 9 9

10 450 2 36 12 12

11 525 1 60 13 12

12 525 1 44 10 9

13 450 2 36 12 12

14 §25 2 40 18 18

415 450 2 108 35 33

16 525 2 76 33 33

17 450 2 60 20 18

18 525 2 16 7 6

19 450 2 16 9 9

20 525 3 32 21 21

21 525 2 48 21 21

22 525 2 16 € 6

23 525 2 16 7 6

Total Volume (m’) 318 306
Is there Satisfactory Storage to Contain the Qz2) Roofwater Yes
runoff?

Noosa Domain Retirement Village, Noosaville 6 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 17

 

 

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Page 20

2D Gag

40 XP-—SWMM MODEL
4.1 Introduction

XP-SWMM Version 10.0 was used to analyse the stormwater runoff and drainage of the
proposed site and the proposed stormwater network.

4.2. Catchments

The catchments used for the XP-SWMM model were taken from the proposed design for
the stormwater drainage network completed in PC-Drain. Catchments that were assumed
to be only overland flow and hence not allowed for in the PC-Drain model were analysed
in the XP-SWMM Model. Catchment runoff that was assumed to be stored and treated by
the infiltration system (Qz2o from roofwater runoff) was not analysed in the model due to
the fact it would be directly stored in the infiltration system and infiltrated through the sand
layer. The Post - Development Catchment Plan can be seen in Figure 4.

4.3. Flows

The catchment flows were calibrated to match the peak flow from the 15min, 20min,
25min, 30min, 45min and 60 minute storm durations for the 100 year ARI event. It was
found that for each catchment the 25 minute storm duration was the worst case scenario
and hence produced the greatest flows and depths.

4.4 Results

The output results from the XP-SWMM model can be seen on Figure 5. It can be seen
that the proposed stormwater drainage network is more than adequate with the greatest
ponding depth achieved at any one node being 140mm. It can also be seen that the total
flow out of the site is 2.07m°/s, which is much lower than the pre-development flow of
2.80m"/s.

Table 4 _ Post - Development Quoo Flows for a storm duration of 25mins.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Post-Development Q1o9 Outlfow (m°/s) — OUT 1 0.052
Post-Development Qioo Outlfow (m°/s) — OUT 2 0.142
Post-Development Qio0 Outlfow (m/s) — OUT 3 0.129
Post-Development Q1o0 Outlfow (m°/s) — OUT 4 0.068
Post-Development Q1o9 Outlfow (m/s) — OUT 5 0.054
Post-Development Q1o0 Outlfow (m*/s) — OUT 6 0.063
Post-Development Q1o0 Outlfow (m*/s) - OUT 7/H 0.541
Post-Development Qo Outlfow (m°/s) — OUT 8/D 0.605
Post-Development Qio9 Outifow (m*/s) — OUT 9/A 0.460
TOTAL Post- Development Qioo Outlfow (m*/s) 2.114
TOTAL Pre - Development Qioo Outifow (m*/s) 2.70
Is there a Non-Worsening effect between Outflows? Yes
Noosa Domain Retirement Village, Noosaville 10 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 21

 

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Page 22

alrEpe

5.0 CONCLUSION

The purpose of this study was to investigate the impact that the proposed development
site on Lot 2 SP 162077 Walter Hay Drive, Noosaville, will have on stormwater runoff
quantities and quality off the site.

It has been concluded that the proposed development will not increase the stormwater
runoff in regards to the existing situation. This can be seen by the significant decrease in
stormwater runoff outflow from the post-developed scenario in comparison to the pre-
development scenario.

A stormwater pipe system is to be constructed allowing flow from the site via three outlets
at the northern and north-western points of the site. A significant network of infiltration
systems are also to be constructed. Not only do these systems decrease the quantity of
runoff from the site but they also treat a significant portion of the runoff from the site to
enhance water quality. This is done by runoff being infiltrated into the 1.5m sand layer
located at approximately RL 1.0m AHD to RL 2.5m AHD via FRC perforated pipes. Due
to this substantial portion of runoff being treated, pollutant concentration levels of runoff
from the site will be significantly reduced. To also reduce pollutant concentration levels
Gross Pollutant Capturing Devices are also to be installed in all field inlets and at the
three piped outlets.

 

Noosa Domain Retirement Village, Noosaville 12 Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 23

alr EDP

APPENDIX A
RAINFALL INTENSITIES

 

Noosa Domain Retirement Village, Noosaville Site Based Stormwater Management Plan
M1717 Revision B 16 August, 2006

Page 24

Dror

Rainfall Intensity for Noosa Heads, Qid

 

Duration

Average Recurrence Interval

 

1Year | 2 Year
(mmi/hr) | (mmfhr)

5 Year | 10 Year | 20 Year | 50 Year | 100 Year
(mm/hr) ea ee (mm/hr) | (mm/hr)

 

129

 

 

 

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201

 

~ 21¢_. ase,
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225

 

 

 

 

 

 

 

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iz

 

485.

 

The rainfall intensities shown above are calculated in accordance with Chapter 2,
Australian Rainfall and Runoff - 1987 Edition.

Noosa Heads, Qid; 26.375 South 153.075 East

04 February,2006

AUS-IFD
Ver 2.0, 2001

 

Noosa Domain Retirement Village, Noosaville
M1717

Site Based Stormwater Management Plan
Revision B 46 August, 2006