Original source · versioned page text
On-Site Effluent Disposal Report
ON-SITE EFFLUENT REPORT – PROPOSED SUBDIVISION
Address : LOT 43 on RP136461
15 Jirrima Crescent
Cooroibah
Client : R. Magee
Date : 23 August 2021
Report No : 200264(S)
Phone: 07 5447 1304
Email: [email protected]
Address: PO Box 1661, Noosa Heads, Qld. 4567
Australian Soil Investigations Pty Ltd
ABN: 11147854439
See the original
The page text is free to read. Viewing or downloading an original file needs an account.
Log in to see the originalSearchable page text hides email addresses. Original files are unchanged and may show email addresses.
Full text of the other 10 pages
Page 2
1.0 COMMISSION:
Our commission was to carry out Site Soil Assessment on the above site and make recommendations for the
disposal of domestic wastewater for the proposed lot reconfiguration. It is proposed to reconfigure Lot 43 on
RP136461 into allotments, namely Lots 1 & 2 The site work was performed in accordance with AS 1547-2012, on
the 10/8/2005.
The client has provided plans of the proposed lot subdivision.(Attached)
2.0 TESTING PROGRAMME:
The above site is located within the Noosa Shire.
During our site evaluation consideration was given to the following:
• the available area for the primary siting of absorption areas and alternative sitings.
• the risk of prejudicing adjoining property and underground water supplies, by seepage or run off from the
site.
• permeability, soil type and soil depth
• drainage, and envisaged seasonal changes in ground water level
• general climate
• slope and the effects of seepage and water run-off from surrounding higher ground
Three test holes were excavated within each allotment in the positions shown in the attached site sketch. These
holes were 100mm diameter x 600 mm deep for the purpose of site soil assessment in accordance with the AS
1547 - 2012. A further 100mm diameter hole was excavated to determine the soil profile. The site was then
classified in accordance with AS 1547 – 2012 On-Site Wastewater Management for the purposes of effluent
disposal.
3.0 SITE DESCRIPTION:
The allotment is vegetated with grasses and scattered low lying trees. All falls are towards the rear of the
allotment. The surface profile in lots 1 & 2 is linear planar . This profile then feeds into a seasonal creek at the rear
of the allotments .
3.1 GEOLOGY & TOPOGRAPHY
A desk top study of the site confirms the following:-
- The site is located in an area identified as Low Landslip Hazard’ on the Noosa Council’s Landslip Hazard
Map
AUSTRALIAN SOIL INVESTIGATION 2 ASI Ref: 210264(A)
Page 3
- Reference to the Australian Geological Map 1:100000 Gympie Special confirms the site is located within the
Quaternary Sediments of the late Holocene period, consisting of alluvial sediments.
4.0 FINDINGS:
The following soil profiles were recorded:
LOT 1 (Proposed)
Depth TEST SITE No 1
100 Sandy Clay CH
200 Med to heavy , dark brown
300 Roots , Moist , moderate.(Cat 5)
400 Silty Clay CH
500 Med to heavy clay., Grey
600 Brown traces of Fine sand
700 Moist , moderate.
800 (CAT 5-6)
900 Silty Clay CH
1000 heavy clay. , pale brown
1100 Mottled grey and red
1200 Moist , massive. (Cat 6)
1300 Silty Clay CH
1400 heavy clay. , pale red
1500 Mottled grey
1600 Moist , massive. (Cat 6)
1700
1800
1900
2000 End
LOT 2 (Proposed)
Depth TEST SITE No 1
100 Sandy Clay CH
200 Med to heavy , dark brown
Roots , Moist , moderate.(Cat 5)
300 Silty Clay CH
500 Med to heavy clay , Grey
600 Brown traces of Fine sand
Moist , moderate.
(CAT 5-6)
700 Silty Clay CH
1000 heavy clay. , pale brown
1100 Mottled grey and red
Moist , massive. (Cat 6)
1200 Silty Clay CH
AUSTRALIAN SOIL INVESTIGATION 3 ASI Ref: 210264(A)
Page 4
1400 heavy clay. , pale red
1500 Mottled grey
1600 Moist , massive. (Cat 6)
1700
1800
1900
2000 End
Note: No seepage or groundwater was encountered.
AUSTRALIAN SOIL INVESTIGATION 4 ASI Ref: 210264(A)
Page 5
The following results were recorded:
ON SITE PERMEABILITY AND SITE ASSESMENT RESULTS:
The following on site permeability results and texture classification were recorded using the Constant Head Method
and in accordance with AS1547-2012.
LOT 1
PERMEABILITY
Test Site: 1 2 3
Fall (mm) 25 25 25
Time (mins) 58 47 62
(secs) 25 15 24
Indicative Permeability (Ksat) 0.0685 0.0847 0.0641
LOT 1
TEXTURE
Test Site: 1 2 3
Soil Category 5 5 5
Structure Moderate Moderate Moderate
LOT 2
PERMEABILITY
Test Site: 1 2 3
Fall (mm) 25 25 25
Time (mins) 63 55 60
(secs) 11 27 12
Indicative Permeability (Ksat) 0.0633 0.0721 0.0664
LOT 2
TEXTURE
Test Site: 1 2 3
Soil Category 5 5 5
Structure Moderate Moderate Moderate
5.0 SITE EVALUATION:
Feature Satisfactory Unsatisfactory
Primary Siting √
Alternative Siting √
Seepage to Adjacent Property √
Seepage to Ground water √
Permeability √
Soil Type √
Soil Depth (min required = 600mm) √
Ground Water Level √
Run-off √
Seepage from Upslope √
AUSTRALIAN SOIL INVESTIGATION 5 ASI Ref: 210264(A)
Page 6
6.0 DISPOSAL SYSTEM RECOMMENDATIONS:
Based on our site assessment and testing we recommend that the most appropriate method of treating and
disposing of effluent to be:
Advanced Secondary Aerated Wastewater Treatment Systems with Covered or Sub-Surface Drip Irrigation.
(As per Noosa Council requirements)
6.1 IRRIGATION SYSTEM CALCULATIONS:
We recommend approved on-site Advanced Secondary Aerated WasteWater Treatment Systems (AWTS) or
approved Aerobic Sand Filtration Systems be used to reduce the pathogen loads in wastewater produced within
the proposed allotments. Effluent quality from the plants must comply with the criteria presented in AS 1547-2012.
We recommend a Covered Surface or Sub-Surface Drip Pressurised Irrigation Irrigation Systems be used in
conjunction with the approved Treatment Systems to distribute the treated effluent in equal dosing across the Land
Application Area. A typical Site layout and arrangement drawing is attached.
TYPICAL CALCULATION:
Minimum requirement q 120 litres per person per day AS 1547 –2012 Appendix H1
Water Supply Tank Water
Number of persons = 6 AS 1547 Table J1
Total Volume Q= 5040 L/week
Soil Category 5 AS 1547 Table M1
Indicative permeability 0.06-0.12 AS 1547 Table M1
DIR 21 mm/week AS 1547 Table M1
2
Disposal Area A= 240 m
WE WOULD THEREFORE RECOMMEND THAT A MINIMUM LAND APPLICATION AREA OF 240 m2 FOR A
CATEGORY 5 SITE BE PROVIDED FOR A TYPICAL 4 BEDROOM DWELLING WITH A MAXIMUM
POPULATION OF 6 PEOPLE.
An additional reserve area of 100% must be provided within each allotment.
Any Irrigation System should be designed in accordance with AS 1547 – 2012 and comply with all relevant
statutory requirements
7.0 CONSTRUCTION GUIDELINES COVERED / SUB SURFACE DRIP IRRIGATION:
A pressurised irrigation system may be used as a means of widely distributing the effluent where vegetation can
directly benefit from such watering. To prevent runoff, the area to be irrigated should be:
(i) level as possible
(ii) sloping areas should be terraced and filled or retained and filled
(iii) rainwater shall be diverted around the area by use of open catch drains or similar from the
irrigation area. Similarly a retention bund should be constructed around the low side of the area to
retain any effluent overflow.
(iv) effluent quality shall conform to AS 1547 2012 and local statutory requirements
AUSTRALIAN SOIL INVESTIGATION 6 ASI Ref: 210264(A)
Page 7
7.1 Pipework
The pump and irrigation system must have a separate effluent storage chamber that matches the electrical starting
requirements of the pump. A volume 200 L is recommended as a minimum. The pump is to have a minimum
capacity of 1.5 times the maximum 30 minute flow rate.
The dripper system can be constructed using either low pressure percolating pipe (Pressure Compensated
Driplines), proprietary drip feed pipe with emitters fixed inside the pipe or low pressure pipe with 5.0mm holes
drilled at 500mm centres. We recommend laying the pipework within a 65 diam. slotted agg drain wrapped in geo-
fabric to prevent root and silt ingress. The pipework is to be installed in accordance with the manufacturers
specifications.
The attached details show the position and construction techniques for either sub-surface or covered surface drip
irrigation.
The pipework is to be spaced to ensure an even distribution of the effluent over the application area. A maximum
spacing of 1000mm in clay soils and 600mm in sand should be adopted. Greater rates of evapo-transpiration is
achieved through closer spacing of the dripper lines and or reducing the spacing between the drip emitters.
The dripper lines should have a stop cock downstream from their connection to the supply line (manifold) and be
brought to the surface at their ends. This will enable flushing of the individual lines and enable easy identification of
blocked lines.
The pipework shall be marked and tested prior to commissioning in accordance with AS1547-2012.
In no instance shall Effluent be used for irrigation of fruit or vegetables.
No Vehicle loading or children’s recreational areas to be applied or constructed within the Land
Application Area.
7.4 Preparation of irrigation area
When a proposed irrigation area has a low permeability, it is particularly important to ensure that the permeability of
the soil in the irrigation area is improved and maintained and that there is an adequate cover of porous and fertile
topsoil to act as immediate storage of effluent applied to it, and to support rapid growth of vegetation on the area to
maximise evaportranspiration.
It is recommended that topsoil be imported to improve rapid growth of vegetation and improve the
evaportranspiration process.
7.5 Requirements of irrigation system
All irrigation pipework and fittings shall comply with all parts of AS 1477 or AS 2698.2. The distribution irrigation
lines shall have a minimum depth of 100mm. There shall be no cross connection between any irrigation pipework
and potable water supply.
Along the boundary of the surface irrigation area there shall be at least two warning signs clearly visible to inform
the occupants of the premises that recycled water is used for irrigation. Each sign shall comply with AS 1319 and
have:
(a) lettering visible at 3m and
(b) wording: Recycled Water
Avoid Contact
DO NOT DRINK
Prior to the use of the system, the warning signs and the landscaping and surface preparation must be completed
AUSTRALIAN SOIL INVESTIGATION 7 ASI Ref: 210264(A)
Page 8
7.6 Siting of the Land Application Area;
The current Code of Practice for On-site Sewerage Facilities provides minimum horizontal/vertical separation
distances for Land Application Areas. They are as follows;
Please Note ASI can provide a final design and location of disposal area when a house location is finalised.
ADVANCED SECONDARY
Sub-Surface or Covered Surface Land Application Areas
Property Boundaries Upslope from the Area - 2.0m
Property Boundaries Downslope from the Area - 4.0m
Dwellings or buildings - 4.0m
In ground swimming Pools - 6.0m
In-ground potable Water Tanks - 15.0m
Dams, Watercourses or Bores - 10.0m
Vertical distance to water table - 0.6m
Footpath 2.0m
Footpath(Downslope) 4.0m
Driveway 2.0m
Driveway (Downslpoe) 4.0m
NOTE:- REFER TO QUEENSLAND PLUMBING AND WASTEWATER CODE FOR SITING OF ON
SITE SEWERAGE FACILITY FOR LOCATION OF TREATMENT PLANT. TREATMENT
PLANT MUST BE 150mm ABOVE Q100 FLOOD LEVEL.
8.0 SYSTEM MAINTENANCE:
The owner of the property shall ensure that all manufacturers maintenance procedures are undertaken in
accordance with the local authority and the manufacturers recommendations for what ever system is installed.
The system must be inspected/tested on a regular basis in accordance with the manufacturers requirements and
all Statutory requirements from relevant local and state government agencies.
9.0 SYSTEM INSTALLATION:
Installation of any system must be undertaken by a qualified plumber in accordance with local authority
requirements and in accordance with the relevant Australian Standards and Australian Building Code.
10.0 DEFINITIONS
Design Loading Rate (DLR)
The long term acceptance rate (LTAR), reduced by a factor of safety, expressed in L/m2/day or mm/day as applied
to the horizontal design area of a land application system.
Design Irrigation Rate (DIR)
The loading rate that applies to the irrigation of a land application area with effluent of a secondary quality. It is
expressed in L/m2/day or mm/week. If a spray irrigation system is used, the secondary effluent is subject to
continuous disinfection.
Durable Aggregate
An aggregate with the grading requirements specified in AS 2758.1 for single-size course aggregate for nominal
sizes from 20mm - 40mm.
Dry Vault
Commonly known as “composting toilets”, a chamber that receives and treats human and domestic organic waste
using a biological degradation or dehydrating process. The only water used is for cleaning or assisting the
biological degradation process.
Geotextile
Any permeable durable synthetic textile material used with foundations, soil, rock, earth or other geotechnical
engineering related material.
Land Application Area
The designated area of land and reticulation system used for the disposal of the treated effluent.
AUSTRALIAN SOIL INVESTIGATION 8 ASI Ref: 210264(A)
Page 9
LTAR The long term average rate an effluent can be adsorbed into the soil of a disposal system, expressed in litres per square meter per day. LTAR is dependant on effluent quality, permeability and organic loading. Permeability The rate clean water is transmitted through a soil, expressed in meters per day. Terrace Where the trenches are in an area where the slope exceeds 15% (approximately 1 in 7) they must be terraced. Water Reduction Fixtures Fixtures include 11/5.5 litre water closets, shower flow restrictors, aerator taps and water conserving washing machines. 11.0 REPORT LIMITATIONS The log sections in this report should be representative of the soil conditions over this site, however, soil conditions can change dramatically over short distances. The person responsible for installing the system must observe the soil profile and ensure it matches the soil profiles recorded in this report. If soil conditions differ from those recorded by us, we must be immediately notified so that further investigation can be carried out and the system design modified if necessary. This work may involve additional fees and costs. This company will not accept any responsibility for additional costs to any party as a result of soil variations. In writing this report, we have also considered all the information supplied to us by our client. Should the client or his agent have omitted to supply us with relevant information, our report may be irrelevant and/or inappropriate. We do not take responsibility for the consequences in such cases and we will make an additional charge if as a result, more testing or rewriting of this report is necessary. The operation of the disposal system is dependant upon the hydraulic load, the type of the material entering the system and the maintenance of the system. As these factors are beyond the control of this company we do not take any responsibility for the long term adequacy of any disposal system constructed on this site or the consequences of its malfunction. WADE HOLMES – QBCC 1120066 for and on behalf of: AUSTRALIAN SOIL INVESTIGATIONS – QBCC 15072110 AUSTRALIAN SOIL INVESTIGATION 9 ASI Ref: 210264(A)
Page 10
Revision Description Date
. .
. . .
. . .
R.Magee
15 Jirrima Cres
Cooroibah
AUSTRALIAN
SOIL INVESTIGATIONS
STD DETAIL Drg No. 210264-Detail
Page 11
Revision Description Date
. . .
. . .
. . .
Surface
Drainage Good.
Vegetation Grasses &
Scattered Trees
BH 2
Borehole location.
ABN11 147 854 439
Slope Title: SITE PLAN - On-Site Effluent Disposal
measured as a percentage gradient from
AUSTRALIAN
high ground to low ground. SOIL INVESTIGATIONS Project R. Magee, 15 Jirrima Crescent
Cooroibah
Rev.
DO NOT DIMENSION OFF THIS DIAGRAM. Date: May 2021 Drg No.210264-ABS .