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19553 - Erosion and Sediment Control Plan
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Log in to see the plans as drawn TEATREE PROPERTIES PTY LTD
EROSION AND SEDIMENT CONTROL PLAN
PARC CORROY SUBDIVISION
LAKE MACDONALD DRIVE, COOROY
DOCUMENT NO: 19553_ESC
DETAILS OF REVISION
REV DATE DETAILS AUTHOR CHECKED
A 08.07.2020 Preliminary Issue DR JF
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Table of contents
Table of contents .............................................................................................................................. 2
1. Introduction ................................................................................................................................ 3
2. Risk Assessment ....................................................................................................................... 3
3. Sediment Basin Sizing .............................................................................................................. 4
4. Conclusions and Recommendations ......................................................................................... 5
Attachment A – Sediment Basin Sizing Calculations ....................................................................... 6
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Introduction
Tod Consulting was engaged by Tea Tree Properties Pty Ltd (Mark Bain Constructions) to prepared
civil engineering design drawings for the planned subdivision at Lake Macdonald Drive, Cooroy
approved by Development Approval reference RAL19/0018. As the works involve bulk earthworks
for the construction of new roads and building pads an Erosion and Sediment Control Plan is
required. This report outlines the risk profile for the individual catchments and work areas of the site
and the proposed control measure to be adopted during the bulk earthworks operations.
This report shall be read in conjunction with the erosion and sediment control plans in the civil
engineering design drawing set reference 19553 – C1101
1. Risk Assessment
The site can be divided into five distinct work areas/catchments, as follows:
1. Road 1 from Chainage 0.0 to Chainage 246 (crest)
2. Road 1 from Chainage 246 to Chainage 448 (cul-de-sac)
3. Road 2 (Wilgee Court) from Chainage 0.0 to Chainahe 80 (end)
4. Lot filling to lot 10 (spoil disposal area)
5. Individual lot building pads and driveways
Note that with the exception of site area 2 & 4 each area discharges to a different/individual location
within the site, so it is not considered necessary to stage the earthworks activies. Notwithstanding
it is likely that some staggering of disturbed areas will naturally occur.
Based on the above area each work area has been assess independently to determine the erosion
risk using the formula outlined in Appendix F of IECA guidelines (T.A.S.K number – equation F1).
Where:
H = Numerical Value of the TASK number
T = Duration of Soil disturbance (months)
A = Total area of soil disturbance (m2)
S = Slope Factor (Tbale F2)
K = Soil erosivity factor (RUSLE K-factor)
As outlined in section F2 if the calculation of the T.A.S.K number is less than 200 then the risk is
considered low.
With the exception of work area 1 the erosion risk of the remaining areas is consdiered to be low
based on the following T.A.S.K number calculations outlined below.
Area 1
Area 1 consists of two catchments that drain to a common sag point at Ch 117
Area 1A
T = 1 month
A = 2340m2
S = 0.69 (Ave slope 4.7%, length 117m)
K = 0.047 (inorganic clays of high plasticity)
H = 76
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Area 1B
T = 1 month
A = 2580m2
S = 1.26 (Ave slope 9.5%, length 129m)
K = 0.047 (inorganic clays of high plasticity)
H = 153
Total TASK number for area 1 = 229 – just exceeds low risk threshold of 200
Area 2 & 4
Area 2 and 4 drain to a common discharge point - existing dam in lot 9.
Area 2
T = 1 month
A = 2800m2
S = 0.73 (Ave slope 4.9%, length 200m)
K = 0.047 (inorganic clays of high plasticity)
H = 96
Area 4
T = 2 months
A = 3500m2
S = 0.21 (Ave slope 1.0%, length 100m)
K = 0.047 (inorganic clays of high plasticity)
H = 69
Total TASK number for area 2 & 4 = 165 – low risk
Area 3
Area 3
T = 1 month
A = 2000m2
S = 0.69 (Ave slope 8.1%, length 80m)
K = 0.047 (inorganic clays of high plasticity)
H = 102 – low risk
Area 5 (individual lot site – example)
T = 1 month
A = 1500m2
S = 0.73 (Ave slope 5%)
K = 0.047 (inorganic clays of high plasticity)
H = 51 – low risk
2. Sediment Basin Sizing
Even though most areas of the site can be considered a low erosion risk it is recommended that
traditional sediment basins be constructed where possible (Type D/F basins). Due the fact that the
majority of the disturbance is longitudinal in shape (ie following the road alignment), there is limited
opportunity and space to construct large sediment basins within the road area and such basins will
need to be removed to allow the road pavement to be constructed. It is envisaged that batters
associated with the road formation will be topsoiled and either mulched or hydromulched to stabilise
these areas prior to the sediment basin being removed to facilitate road construction.
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Sediment basin sizing has been calculated using the procedure outlined in Appendix B of IECA
guidelines and the soil loss equation (RUSLE) in Appendix E. Individual spreadsheet calculations
are attached for each of the above catchments at the back of this report – ATTACHMENT A.
Note that whilst area 2 & 4 ultimately discharge to the same location each area will have its own
sediment basin/containment area, although it may also be possible to utilise the existing dam in lot
9 for this purpose.
It is not proposed to construct sediment basins for individual lot house pads and driveways.
3. Conclusions and Recommendations
As outlined above, the majority of the site is considered a low erosion risk. Notwithstanding
sediment basins will be constructed and maintained during the bulk earthworks operations where
possible and as outline in the design plans.
Prepared by Doug Reynolds
RPEQ 9072
Tod Consulting Pty Ltd
9 July 2020
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Attachment A – Sediment Basin Sizing Calculations
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Attachment A — Sediment Basin Sizing Calculations
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RUSLE CALCULATION SPREADSHEET
Note: These "Detailed Calculation" spreadsheets relate only to high erosion hazard lands as identified in table F1 or where the designer chooses to use
the RUSLE to size sediment basins. The "Standard Calculation" spreadsheets should be used on low erosion hazard lands as identifiedin Table F1 and
where the designer chooses not to run the RUSLE in calculations.
1. Site Data Sheet
Site Name: Parc Cooroy
Site Location: Lake Macdonald Drive Lake Macdonald
Precinct: Area 1 - Road 1 Ch 0.0-246
Description of Site: Subdivision
Sub-catchments
Site area Remarks
1A 1B
Disturbed catchment area (ha) 0.24 0.24
Soil analysis (enter sediment type if known, or laboratory particle size data)
Soil Texture Group D D 0 0 0 0
Rainfall data
85%ile 5 day event for Nambour from Table
x-day, y-percentile rainfall event 56.2 56.2
B5
IFD: 2-year, 6-hour storm (if known) 14.9 14.9
RUSLE Factors
Rainfall erosivity (R -factor) 4930 4930 0 0 0 Auto-filled from above
Soil erodibility (K -factor) 0.047 0.047 Table E5
Slope length (m) 119 127
Slope gradient (%) 4.7 9.7
Length/gradient (LS -factor) 1.36 3.50 0.00 0.00 0.00 From Table E3.3
Erosion control practice (P -factor) 1.3 1.3
Ground cover (C -factor) 1 1
Calculations
Soil loss (t/ha/yr) 410 1054 0 0 0 0 RUSLE - refer section E3
Soil Loss Class D D D 0 0 0
Soil loss (m3/ha/yr) 315 811 0 0 0 0
Volumetric runoff coefficient 0.72 0.72 Refer Table B7
Settling Zone Storage (m3) 97 97 0 Section B - step 5b
Sediment basin storage volume, m3 13 32 0 0 0 0 2 months runoff volume
TOTAL SUBCATCHMENT BASIN VOLUME 110 129 0 0 0 0
TOTAL BASIN VOLUME 239
Basin Dimensions
Depth (nominal) 1.5
Length to width ratio 2.5
Width 8
Length 20
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RUSLE CALCULATION SPREADSHEET
Note: These "Detailed Calculation" spreadsheets relate only to high erosion hazard lands as identified in table F1 or where the designer chooses to use
the RUSLE to size sediment basins. The "Standard Calculation" spreadsheets should be used on low erosion hazard lands as identifiedin Table F1 and
where the designer chooses not to run the RUSLE in calculations.
1. Site Data Sheet
Site Name: Parc Cooroy
Site Location: Lake Macdonald Drive Lake Macdonald
Precinct: Area 2 - Road 1 - Ch 246 to end
Description of Site: Subdivision
Sub-catchments
Site area Remarks
2
Disturbed catchment area (ha) 0.28
Soil analysis (enter sediment type if known, or laboratory particle size data)
Soil Texture Group D D 0 0 0 0
Rainfall data
85%ile 5 day event for Nambour from Table
x-day, y-percentile rainfall event 56.2
B5
IFD: 2-year, 6-hour storm (if known) 14.9
RUSLE Factors
Rainfall erosivity (R -factor) 4930 4930 0 0 0 Auto-filled from above
Soil erodibility (K -factor) 0.047 Table E5
Slope length (m) 200
Slope gradient (%) 4.9
Length/gradient (LS -factor) 2.00 0.00 0.00 0.00 From Table E3.3
Erosion control practice (P -factor) 1.3
Ground cover (C -factor) 1
Calculations
Soil loss (t/ha/yr) 602 0 0 0 0 0 RUSLE - refer section E3
Soil Loss Class D D D 0 0 0
Soil loss (m3/ha/yr) 463 0 0 0 0 0
Volumetric runoff coefficient 0.72 Refer Table B7
Settling Zone Storage (m3) 113 0 0 Section B - step 5b
Sediment basin storage volume, m3 22 0 0 0 0 0 2 months runoff volume
TOTAL SUBCATCHMENT BASIN VOLUME 135 0 0 0 0 0
TOTAL BASIN VOLUME 135
Basin Dimensions
Depth (nominal) 1
Length to width ratio 2.5
Width 7.3
Length 18.25
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RUSLE CALCULATION SPREADSHEET
Note: These "Detailed Calculation" spreadsheets relate only to high erosion hazard lands as identified in table F1 or where the designer chooses to use
the RUSLE to size sediment basins. The "Standard Calculation" spreadsheets should be used on low erosion hazard lands as identifiedin Table F1 and
where the designer chooses not to run the RUSLE in calculations.
1. Site Data Sheet
Site Name: Parc Cooroy
Site Location: Lake Macdonald Drive Lake Macdonald
Precinct: Area 3 - Road 2 Ch 0.0-80
Description of Site: Subdivision
Sub-catchments
Site area Remarks
3
Disturbed catchment area (ha) 0.20
Soil analysis (enter sediment type if known, or laboratory particle size data)
Soil Texture Group D D 0 0 0 0
Rainfall data
85%ile 5 day event for Nambour from Table
x-day, y-percentile rainfall event 56.2
B5
IFD: 2-year, 6-hour storm (if known) 14.9
RUSLE Factors
Rainfall erosivity (R -factor) 4930 4930 0 0 0 Auto-filled from above
Soil erodibility (K -factor) 0.047 Table E5
Slope length (m) 80
Slope gradient (%) 8.1
Length/gradient (LS -factor) 2.05 0.00 0.00 0.00 From Table E3.3
Erosion control practice (P -factor) 1.3
Ground cover (C -factor) 1
Calculations
Soil loss (t/ha/yr) 618 0 0 0 0 0 RUSLE - refer section E3
Soil Loss Class D D D 0 0 0
Soil loss (m3/ha/yr) 475 0 0 0 0 0
Volumetric runoff coefficient 0.72 Refer Table B7
Settling Zone Storage (m3) 81 0 0 Section B - step 5b
Sediment basin storage volume, m3 16 0 0 0 0 0 2 months runoff volume
TOTAL SUBCATCHMENT BASIN VOLUME 97 0 0 0 0 0
TOTAL BASIN VOLUME 97
Basin Dimensions
Depth (nominal) 1
Length to width ratio 2.5
Width 6.2
Length 15.5
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RUSLE CALCULATION SPREADSHEET
Note: These "Detailed Calculation" spreadsheets relate only to high erosion hazard lands as identified in table F1 or where the designer chooses to use
the RUSLE to size sediment basins. The "Standard Calculation" spreadsheets should be used on low erosion hazard lands as identifiedin Table F1 and
where the designer chooses not to run the RUSLE in calculations.
1. Site Data Sheet
Site Name: Parc Cooroy
Site Location: Lake Macdonald Drive Lake Macdonald
Precinct: Area 4 - lot 10 pad
Description of Site: Subdivision
Sub-catchments
Site area Remarks
4
Disturbed catchment area (ha) 0.33
Soil analysis (enter sediment type if known, or laboratory particle size data)
Soil Texture Group D D 0 0 0 0
Rainfall data
85%ile 5 day event for Nambour from Table
x-day, y-percentile rainfall event 56.2
B5
IFD: 2-year, 6-hour storm (if known) 14.9
RUSLE Factors
Rainfall erosivity (R -factor) 4930 4930 0 0 0 Auto-filled from above
Soil erodibility (K -factor) 0.047 Table E5
Slope length (m) 95
Slope gradient (%) 1
Length/gradient (LS -factor) 0.20 0.00 0.00 0.00 From Table E3.3
Erosion control practice (P -factor) 1.3
Ground cover (C -factor) 1
Calculations
Soil loss (t/ha/yr) 60 0 0 0 0 0 RUSLE - refer section E3
Soil Loss Class D D D 0 0 0
Soil loss (m3/ha/yr) 46 0 0 0 0 0
Volumetric runoff coefficient 0.72 Refer Table B7
Settling Zone Storage (m3) 135 0 0 Section B - step 5b
Sediment basin storage volume, m3 3 0 0 0 0 0 2 months runoff volume
TOTAL SUBCATCHMENT BASIN VOLUME 138 0 0 0 0 0
TOTAL BASIN VOLUME (4) 138
Basin Dimensions
Depth (nominal) 1
Length to width ratio 2.5
Width 7.4
Length 18.5