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Storm Water - Lex Toth
Attached to the e-mail Operational Works Application OPW19/0133 - DA Form 1 - Pre-lim Construction Management Plan - Civil Plans - 10 Opal St Cooroy.
Attached to the e-mail MCU19/0013 & RAL19/0003 - Response to Information Request - 10 Opal St Cooroy.
PROPOSED DUPLEX
INTEGRATED WATER MANAGEMENT PLAN
VERSION 0
FOR
ROBERT ERHARTER
HOUSE 10
LOT 6 on RP82318186 OPAL LANE,
COOROY
APRIL 2019
Callaghan & Toth
Civil, Environmental &
Hydraulic Engineers
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Page 2
Callaghan & Toth
DOCUMENT HISTORY
Document Reference: No: 1905 SWQMP_Rev0.doc
Project Manager: Robert Erharter
Author: Lex Toth
Client: Robert Erharter
Contact Person: Robert Erharter
DISTRIBUTION LIST
POSITION ON
NAME ORGANISATION MANAGEMENT REVISION REVISION REVISION REVISION
TEAM 0 1 2 3
Robert Erharter Client 1
Lex Toth Callaghan & Toth Author 1
Billy Glover Noosa Council Assessment Officer 1
REVISION LIST
REVISION DATE DISTRIBUTED ISSUED BY CHECKED BY
0 10 April 2019 Lex Toth Jane Davissen
The information contained in this report is confidential and proprietary to Callaghan & Toth Civil,
Environmental & Hydraulic Engineers. It may only be used by the person to whom it is provided,
for the stated purpose for which it is provided, and must not be imparted to any third person
without the prior written approval of Callaghan & Toth. Callaghan & Toth reserves all legal rights
and remedies in relation to infringement of its rights in respect of its confidential information.
©
Callaghan & Toth
2019
Erthart 1905 SWMP_Rev0.doc April 2019 2
1905
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Callaghan & Toth
CONTENTS
1. INTRODUCTION................................................................................................. 4
1.1 Response to Conditions of Approval ............................................................ 4
2. DESCRIPTION.................................................................................................... 4
3. FLOODING ......................................................................................................... 4
4. STORMWATER DESIGN AND ASSESSMENT.................................................. 8
4.1 Proposed On-Site Stormwater Treatment Process ...................................... 8
4.1.1 Rainfall Data ........................................................................................... 8
4.2 Hydrology ..................................................................................................... 8
CONCLUSIONS ......................................................................................................... 9
APPENIDX 1: Summary of Retention Calculation Results ....................................... 10
LIST OF REFERENCES
1. EN HEALTH (2004) Guidance on the Use of Rain Water Tanks.
2. Engineers Australia (2006) Australian Runoff Quality. Australian Runoff Quality
Guidelines.
3. Healthy Waterways (2006) Water Sensitive Urban Design Technical Design
Guidelines for South East Queensland
4. Queensland Development Code Part 4.3 (Oct 2008) Alternative Water Sources.
5. Water by Design, MUSIC Modelling Guidelines for South East Queensland – Version
1 (December 2010)
6. Water by Design, Deemed to Comply Solutions – Stormwater Quality Management
(South East Queensland), May 2010
7. Wong, T., Breen, P. & Lloyd, S. (2000) Water Sensitive Road Design – Design
Options for Improving Stormwater Quality of Road Runoff. CRC for Catchment
Hydrology Technical Report No 00/1.
LIST OF FIGURES
Figure 1.1 Proposed Stormwater Quality Management Layout 6
Figure 4.1 Typical Rainwater Tank 7
LIST OF TABLES
Table 1.1 Response to Information request 5
Erthart 1905 SWMP_Rev0.doc April 2019 3
1905
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Callaghan & Toth
1. INTRODUCTION
The site subject to this report is at No.10 Opal Street Cooroy. One existing house on the lot
is to be added to by a new dwelling to the rear.
The stormwater management assessment undertaken in this project considers the increase
in impervious area of the lot due to the proposed additional building and measures which
can be incorporated into the design to attenuate the resultant increase in runoff back to
predevelopment levels.
The existing dwelling catchment drains to Opal Street.
The new dwelling site currently drains to Opal Lane as shown on Figure 1.1. the proposed
new drainage system will replicate the existing catchment split.
1.1 Response to Conditions of Approval
TABLE 1.1: Response to Information Request
NUMBER CONDITION RESPONSE
7a Detail of proposed tank (location, dimensions, level) Details shown on Figure
1.1
7b Detail of proposed drainage system (pipe sizes and Details shown on Figure
grades) 1.1
7c Existing and proposed surface levels to demonstrate that Details shown on Figure
suitable clearances can be achieved 1.1
7d Comment regarding the capacity of the existing drainage Refer Section 4.2 of this
system in Opal Street to be achieved report
7e Indications of the various catchment areas within the site Refer Section 3 of this
and certification that states if the development is report
constructed in accordance with the design there will be no
worsening of drainage conditions on adjoining properties,
Opal Street and Opal Lane.
2. DESCRIPTION
The site is on a 1,009 m2 parcel of land which has frontage to both Opal Street and Opal
Lane. There is an existing underground drainage system with a channel in Opal Street. Opal
Lane road has recently been extended past this site to serve a new development at 8 Opal
Lane.
3. FLOODING
The existing house drains toward Opal Street. The downpipes discharge into an existing
gully pit in Opal Street.
No.8 Opal Street has an overland flow path along the west boundary which is designed to
take the stormwater overland flow from sag in Opal Street.
The runoff from the existing half of the property currently drains to a low point at the south
west corner of No. 10 Opal Lane. The plan figure 1.1 shows the new development will
maintain this flow path and therefore have no effect on the neighbouring property.
Erthart 1905 SWMP_Rev0.doc April 2019 4
1905
Page 5
Callaghan & Toth The rear half of Opal Street drains to Opal Lane and the laneway kerb capacity has been designed to convey this runoff. This SWMP proposes to not alter these catchment boundaries. Erthart 1905 SWMP_Rev0.doc April 2019 5 1905
Page 6
LEGEND — EXISTING SERVICES . :
| \ m4 ae Toth Environmental
BOUNDARY :
us Environmental &
EASEMENT Hydraulic Engineers
féfis/ ssi spf is f PO BOX 2305
BUILDING NOOSA HEADS 4567
AAA CONCRETE y! 6/41 Sunshine Beach Road
=] Phone 54749081, Fax 54749041
— DRAINAGE www.callaghanandtoth.com.au
designed | ADT datum AHD DERIVED
i ste es — EDGE. OF ‘BITUMEN crown 1 oy 10192
$i FENCE checked [CL__| Origin (BM.) RL 111.413
| | —S —p ——s —— — __ DRAINAGE CHANNEL
approved
N ooo CEE SURVEYED. BY
OVERHEAD POWER MAX WATTERSON & ASSOCIATES
PHONE (07) 54426121
SEWER
(———e—————————™
SEWER RISING MAIN project
W ———— ___ WATER MAIN PROPOSED 2 LOT
T ———— _ TELSTRA 10 OPAL STREET
COOROY Q. 4563
@™ WATER METER
Ke)
i | TELSTRA PIT ————————
Client
POW
OWER POLE ROBERT ERHARTER
a
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LEGEND — PROPOSED SERVICES title
OPAL LANE STORMWATER
Le NEW CONCRETE DRIVEWAY DETENTION & DRAINAGE PLAN
OO)
—
DN100 PVC STORM WATER PIPE HOUSE 10
+ ——— —__DN9O PVC STORMWATER PIPE LOT 6 on RP 82318
CATCHMENT BOUNDARY Parish of TEWANTIN
County of MARCH
DETENTION TANK 0 DEY SUNSHINE COAST COUNCIL
DETENTION TANK T0 DETAIL 5
Locality of COOROY
En
_————
SCALE
100mm% DOWNPIPE FROM GUTTERS p=] ]0_1.25 2.5 3.75 5 6.25 Meters 12.5}
SS
scale SCALE SHOWN IS ORIGINAL DRAWING SCALE
3,000L TANK
WET LINE TO TANK INLET
Sw SW
WET LINE TO TANK INLET
NEW 3,000L ROOFWATER
DETENTION TANK TO DETAIL
1:250(A3) DO NOT SCALE FROM THIS DRAWING
USE ONLY DIMENSIONS PROVIDED
REVISIONS
revision
A | PREMILIMARY
100mm OVERFLOW PIPE
FILL 0.15m DEEP IN CORNER
To PROVIDE PIPE coveR| |
NEW METAL KERB ADAPTER
FILES
32mm LOW FLOW OUTLET COMPUTER DIRECTORY
XAVJOBS\CT PRON PROG\
aN POR APPROVAL
Sheet 1 of 1 sheets
300x300 FIELD INLET CONCRETE SLAB =
drawing number
DETENTION TANK DETAIL FIGURE 1.1
NOT TO SCALE
XK date 10 APRIL 2019 yy,
Page 7
OVERFLOW PIPE TO GULLY PIT
EXTENDED DETENTION DN32
OUTLET TO GULLY PIT
Co
ROOFWATER DOWNPIPE
eli
sot”
FIRST FLUSH DIVERSION
ia TO GARDEN BEDS
Callaghan & Toth
Civil, Environmental &
Hydraulic Engineers
8/41 Sunshine Beach Road
P.O. Box 2305
{ NOOSA HEADS 4567
Ph: 54749081
= www.callaghanandtoth.com.au
project
PROPOSED DUPLEX
location
10 OPAL LANE,
COOROY
TYPICAL RAINWATER TANK
Figure 4.1
Scale:NTS
Page 8
Callaghan & Toth 4. STORMWATER DESIGN AND ASSESSMENT 4.1 Proposed On-Site Stormwater Treatment Process The developed site was divided into Sub-Catchments as shown on Figure 1.1 and the detention system is listed below: 1. Rainwater Detention Tanks will be required to collect water from all the roof areas of the new house. A total of two (2) tanks with a capacity of 3,000 litres per tank will be provided for the new house. The tanks are to an overflow pipe discharging to the underground drainage system. The total tanks capacity is to be 6,000 litres and is adequate for the approximate attenuation of runoff back to predevelopment concentrations for AEP1%, 10%, 50%. 4.1.1 Rainfall Data The meteorological data used for the BOM IFD table for Cooroy was used for the runoff calculations 4.2 HYDROLOGY The site has been modelled using HydroCAD 10 to determine the detention capabilities of the rainwater tanks. The rainwater detention tanks adopted have been sized so that runoff concentrations are reduced back to predevelopment levels as shown in our calculations in Appendix 1. As the existing runoff and catchment extents to Opal Street is not to be affected by this development, there will be no change to the capacity of drainage to Opal St.. As the new runoff from the new house in Opal Lane is to be attenuated to pre-development levels, there will be no change to the capacity of existing drainage in Opal Lane. Erthart 1905 SWMP_Rev0.doc April 2019 8 1905
Page 9
Callaghan & Toth CONCLUSIONS The Rainwater Detention Tanks are able to attenuate the runoff concentrations back to pre development levels and so the development will not have an impact on the hydrology of the existing Lane. Erthart 1905 SWMP_Rev0.doc April 2019 9 1905
Page 10
Callaghan & Toth APPENIDX 1: Summary of Retention Calculation Results Erthart 1905 SWMP_Rev0.doc April 2019 10 1905
Page 11
APPENDIX 1: SUMMARY OF RETENTION CALCULATION RESULTS
10 OPAL ST DUPLEX
Pre-Development Case
501m² Catchment
tc = 6 min., C=0.70
Cf50%=0.85, Cf10%=1.00, Cf1%=1.20
Q1% flow = 0.0346 m³/s
Q10% flow = 0.0198 m³/s
Q50% flow = 0.0125 m³/s
Post-Development Case (No Detention)
501m² Catchment
Roof = 222m²
Grass/Landscaping/Driveway = 279m²
tc = 6 min., Roof C=0.98, Grass/Landscape/Driveway C=0.73
Cf50%=0.85, Cf10%=1.00, Cf1%=1.20
Q1% flow = 0.0384 m³/s
Q10% flow = 0.0238 m³/s
Q50% flow = 0.0150 m³/s
Post-Development Case (with Detention)
501m² Catchment
Roof = 222m²
Grass/Landscaping/Driveway = 279m²
tc = 6 min., Roof C=0.98, Grass/Landscape/Driveway C=0.73
Cf50%=0.85, Cf10%=1.00, Cf1%=1.20
Q1% flow = 0.0255 m³/s
Q10% flow = 0.0158 m³/s
Q50% flow = 0.0105 m³/s