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SITE CLASSIFICATION
ON-SITE SEWAGE MANAGEMENT REPORT
VERSION 1
1192 WALLAROO ROAD
WALLAROO
Lot 15 DP 253616
WALLAROO NSW 2618
08 September 2020
FRANKLIN CONSULTING AUSTRALIA PTY LIMITED
GPO Box 837 CANBERRA ACT 2601
www.soilandwater.net.au
Franklin Consulting Australia Pty Limited, trading as Soil and Water, offers expert advice and
services to the agriculture, development and environmental conservation sectors. We provide
soil and water management advice, undertake land capability and soil assessment, erosion and
sediment control, and soil conservation, catchment and property management planning. We
have extensive experience in both government and private sectors in senior management and
consulting roles.
We provide our services to individual land holders, sub-division developers, surveyors,
commercial business owners, and land development and regulatory agencies.
Principal Consultant
John Franklin M App Sc, BSc, EIANZ
John Franklin has over 26 years’ experience in natural
resource management in the ACT, the Upper
Murrumbidgee region in New South Wales and the tropical
farming regions in North Queensland.
Franklin Consulting Australia Pty Ltd holds current Workers
Compensation Insurance with CGU (Policy Number O/16-
5885) and Professional Indemnity cover of $10,000,000
and Public Liability cover of $10,000,000 with Lloyds.
Contact details: GPO Box 837
Canberra ACT 2601
P 02 6179 3491
M 0490 393 234
admin@soilandwater.net.au
www.soilandwater.net.au Disclaimer
This report is based on the information provided by the client regarding the proposed development and
the condition of the site on the date of the site visit. The recommendations in this report are not valid if
there are subsequent changes to the proposed development or changes to the site such as earthworks
or vegetation clearing. Franklin Consulting Australia Pty Ltd takes no responsibility for the installation of
wastewater management systems.
SOIL AND WATER 3
CONTENTS
SUMMARY .......................................................................................................... 4
REPORT SCOPE AND TECHNICAL REFERENCES ............................................................... 5
LANDSCAPE CHARACTERISTICS ................................................................................. 6
SITE INFORMATION ............................................................................................... 7
SITE ASSESSMENT .............................................................................................. 11
SOIL ASSESSMENT .............................................................................................. 14
SYSTEM SELECTION ............................................................................................. 15
RECOMMENDED EFFLUENT MANAGEMENT PRESCRIPTIONS ............................................. 16
SIZING EFFLUENT DISPOSAL AREA ........................................................................... 21
SITE AND SOIL LIMITATION ASSESSMENT .................................................................. 22
APPENDIX 1: SOIL PROFILE DESCRIPTIONS................................................................. 26
APPENDIX 2: SUPPORTING INFORMATION .................................................................. 28
APPENDIX 3: SITE CLASSIFICATION INFORMATION ........................................................ 31
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 4
SUMMARY
Development Connection of the existing 3-bedroom dwelling (to be
extended with a pool-house and bathroom) and separate
proposed office/study/guest accommodation (modelled as a
separate 2-bedroom accommodation).
1192 Wallaroo Road
Wallaroo
Lot 15 DP 253616
NSW
Owner/Developer Sven Baker
Expected wastewater load/day: Daily effluent load is based on the main 3-bedroom dwelling
(4 potential occupants @ 120L/person/day), plus a separate 2-
bedroom dwelling (3 potential occupants @ 120L/person/day),
therefore 840L/day.
Recommended treatment system: Aerated Wastewater Treatment System including
disinfection.
[The make and model of treatment system will be selected
from NSW Health Accredited secondary treatment systems
in consultation between the installer and landholders]
Recommended effluent dispersal system: Treated and disinfected effluent will be dispersed
through a surface spray irrigation field covering a minimum
area of 450m2
Special conditions/comments: A moveable sprinkler line fitted with 5 heavy droplet
sprinklers at 5-metre spacings and with adequate length to
reach the entire 450m2 irrigation area is considered suitable
for the site. A surface drip irrigation field or combination of
both, will also be acceptable.
The site is generally not suited to a septic tank and absorption
bed system due to low permeability light clay subsoil.
Existing System: The existing dwelling is connected to a septic tank and
absorption bed system. This system is not adequate for the
proposed development and will be permanently
decommissioned.
Site classification: M-Moderately Reactive (in accordance with AS 2870).
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 5
REPORT SCOPE AND TECHNICAL REFERENCES
The report assesses land near the proposed development to identify specific areas required for
the optimal functioning of an on-site sewage management system.
This involves excluding land with major physical constraints such as steep slopes, rocky
outcrops, poor drainage, areas within buffer distances of property boundaries watercourses,
storages, flow lines and existing and proposed buildings.
All information required by the approving authority, usually regional Councils, is contained in
this report, including suitable types of sewage management systems, management
prescriptions, site plan and photographs, with supporting information in this report including
nutrient balance and limitation tables.
The report also refers to, or relies on, standards and technical references listed below.
On-site Sewage Management for Single Households (The Silver Book) NSW Govt,
1998.
AS/ANZ Standard 1547:2012 On-site Domestic Wastewater Management.
Yass Valley Local Environment Plan, 2013.
Soil Landscapes of the Canberra 1:100,000 Sheet. Jenkins, B.R. (2000) Department
of Land and Water Conservation, NSW.
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 6
LANDSCAPE CHARACTERISTICS
LANDSCAPE The landscape is identified as the Williamsdale Soil Landscape Unit and includes
undulating rises and valleys formed on Silurian Volcanic parent material. Local
relief is 5-50 m with gentle slopes of less than 10% on elevations between 550-
650m. Outcropping rock is uncommon.
The landscape in the vicinity of the new dwelling is cleared with scattered
remnant native vegetation and some plantings. Grazing is the predominant and
historic land use.
The local landscape is extensively cleared and modified for rural land use.
The land is gently sloping at 6-9% to the west and south.
SOILS Detailed soil profile descriptions are provided in Appendix 1 of this report.
Moderately well drained and moderately deep Red and Brown Chromosols are
situated in the area identified as suitable for effluent disposal, refer Figure 7.
These soil types are part of the Williamsdale Soil Landscape Unit1 and are
comprised of a light brown silty loam topsoil overlaying a red/brown silty clay
loam. Depths range 60-90 cms.
The analytical data for the Williamsdale Landscape in the Soil Landscapes of the
Canberra 1:100,000 Sheet survey report shows variable phosphorous sorption
levels across the levels of the profile ranging from moderate to high. Soils are
non-saline subsoils and low exchangeable sodium. As such the soils are free of
any significant chemical limitations to effluent dispersal via absorption
.
1 Soil Landscapes of the Canberra 1:100,000 Sheet, Jenkins, 2000 (DLWC)
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 7
SITE INFORMATION
Local Government Area: Yass Valley Council
Address/locality: 1192 Wallaroo Road
Wallaroo
Lot 15 DP 253616
NSW 2618
Owner/Developer: Sven Baker
Block Configuration:
Figure 1a: Regional location
Figure 1b: Block configuration
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 8
WATER SUPPLY: Non-reticulated – roof catchment – tank storage for domestic
water.
EXPECTED WASTEWATER LOAD (LITRES/DAY): The design in this report is based on the
existing 3-bedroom dwelling which will be extended to include a
pool-house with bathroom facilities, and separate
office/study/guest accommodation which has been considered as
a separate 2-bedroom dwelling for design purposes. The design
occupancy of these two dwellings is 7 persons which will
generate a design wastewater load of 840L/day (@
120l/person/day).
LOCAL EXPERIENCE: Most secondary treatment systems combined with surface spray
effluent irrigation work well in similar landscapes where soil
depth is a limitation to subsoil disposal. Secondary treatment
systems (AWTS) need to be maintained regularly, in accordance
with council regulations and prescriptions in this report.
Figure 2: Looking across proposed site for the pool-house extension
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 9
Figure 3: Looking west across the effluent irrigation area
Figure 4: 3-bedroom dwelling to be extended with pool-house including bathroom
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 10
Figure 5: Looking south east across the proposed effluent irrigation area
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 11
SITE ASSESSMENT
CLIMATE: The climate is typically a cool and moderately dry climate. Average rainfall for
the area is 600 – 800 mm. Warm summers with large evaporative deficit, cool
winters with small evaporative deficit; median summer monthly rainfall for
Canberra airport 49 mm; median monthly winter rainfall 38 mm; mean monthly
summer evaporation is 177 mm, mean monthly winter evaporation is 60 mm.
Climate is well suited for the land application of treated effluent via surface
spray irrigation (combined with secondary treatment).
RAINFALL WATER BALANCE ATTACHED: Yes. Refer to Sizing the Effluent Disposal Area.
LAND APPLICATION AREA CALCULATED: Yes. Refer to Sizing the Effluent Disposal Area.
WET WEATHER STORAGE CALCULATION ATTACHED: Not applicable (rainfall < 1,000mm).
FLOOD POTENTIAL:
Land application area above 1:20 year flood: Yes
Land application area above 1:100 year flood: Yes
Electrical components above 1:100 year flood: N/A
EXPOSURE: Site is reasonably exposed with scattered landscaping vegetation providing
limited shading to the irrigation area.
Exposure is suitable for the surface irrigation of effluent.
SLOPE: The effluent dispersal area has a gentle slope of approximately 6-9% to the north
and west.
Slopes are not a constraint to effluent dispersal by surface irrigation.
LANDFORM: Slope form of the site is divergent in the proposed effluent disposal area and
building precinct.
Landform is suited to effluent dispersal by surface irrigation
RUN-ON: Limited run-on water will impact the site due to upslope landscaping and
associated drainage infrastructure.
Run-on water is not a constraint to effluent disposal on the site
SEEPAGE: No seepage was evident on the property.
EROSION POTENTIAL: The irrigation area has an established groundcover of improved
pasture/lawns which mitigates the erosion risk.
Limited erosion potential will be addressed through the maintenance of 100%
groundcover on the effluent dispersal area
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 12
SALINITY: The area is not mapped in the Yass Valley Local Environment Plan (2013) salinity
mapping or high soil erodibility.
Salinity is not a constraint to effluent disposal.
SITE DRAINAGE: Site drainage occurs as overland flow across the site. There is a drainage
depression to the north and west of the irrigation area and Murrumbidgee River
fronts the western boundary. Both of these drainage features will require buffers
from the proposed effluent irrigation area.
The defined drainage depressions will require 40-metre buffers from effluent
disposal practices.
40-metre drainage buffers are required from the drainage depression and 100-
metres is required between the Murrumbidgee River and the effluent irrigation
area on the lot.
FILL: No fill was detected on the property. The construction sites (pool-house and
office/study/guest accommodation) are existing levelled areas. No fill will be
deposited in the effluent disposal area.
There will be no areas of fill in the effluent dispersal area.
GROUNDWATER:
Horizontal distance to groundwater well used for potable domestic supply: There are no
known bores used for potable water supply in the area.
Groundwater vulnerability map category: The area is mapped moderate groundwater
vulnerability in the Murrumbidgee Groundwater Vulnerability Map (DLWC).
Bores in area and purpose: There are no bores within 500 m of the effluent dispersal site.
The closest bore (GW401027) is located 750 metres south of the proposed
effluent dispersal area (refer Figure 6). This bore has a depth of 46 m.
The effluent management practices proposed in this report will not impact these
bores or the groundwater aquifer due to:
• spatial separation of > 500 m,
• depth to water bearing zones of (>40m),
• low transmissivity of fractured rock aquifer systems, and
• low application rate of secondary treated and disinfected effluent to the
surface.
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 13
Figure 6: Location of bores (National Bore Database)
BUFFER DISTANCE FROM TREATMENT SYSTEM TO:
Perennial rivers and creeks: Not required
Drainage depressions: 40m
Other sensitive environment: 3/6m (upslope/downslope driveways)
250m (bore)
Boundary of premises: 3/6m (upslope/downslope driveways)
Swimming pools: Not applicable
Buildings: 15m (dwellings) 6m (outbuildings) [Buffers distances as per Silver Book – Table 5]
IS THERE SUFFICIENT LAND AREA FOR:
Application system including buffers: Yes, refer Figures 7a, 7b
Reserve application system: Yes, refer Figures 7a, 7b
SURFACE ROCK AND OUTCROP:
Rocky outcrops are less than 10% and a minor constraint.
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 14
SOIL ASSESSMENT
Depth to bedrock or hardpan: 0.5-1.0
Depth to high soil water table: >1.0m
Minimum Separation distance: >600mm
Hydraulic loading rate
Soil texture:
Soil structure:
Permeability
(from table M1 of AS1547:2012):
Recommended design loading rate
for effluent irrigation
(from table M1 of AS1547:2012):
Silty Clay Loam
Moderate
0.5-1.5 m/day
4 mm/day
Coarse fragments: 5-10%
Bulk density* 1.6-1.8 t/m3 in topsoil, 1.5 t/m3 in subsoil
PH field*: 5.4 in topsoil, 6.0 in subsoil
Electrical conductivity dS/m*: 0.10 in topsoil, 0.11 in subsoil
Exchangeable sodium %*: 0.10 in topsoil, 4.2 in subsoil
Cation exchange capacity (mequiv/100g)*: 5.5 in topsoil, 11.4 in subsoil
Phosphorous sorption capacity mg/kg*: 122(topsoil) 447 (subsoil)
Geological feature
Discontinuities:
Fractured rock:
None
None
Soil landscape reference*: Williamsdale Profile
Dispersiveness EAT class*: 3(2) in topsoil, 2(1) in subsoil
Site Classification (AS 2870):
Pool-house & Office/Study Building
Envelopes
M - Moderately Reactive
* extrapolated from Jenkins (2000) Soil Landscapes of the Canberra 1:100,000. DLWC
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 15
SYSTEM SELECTION
Consideration of connection to
centralised sewerage system:
Distance: Greater than 5 kms
Potential for future connection: None
Potential for reticulated water: None
Type of land application system
best suited:
Surface spray or drip irrigation to improved perennial
pasture/grass &/or landscaped areas.
Suited to site and soil conditions.
Enables beneficial reuse of effluent in a water
constrained environment.
Subsoil absorption is not suited to the site due to low permeability clay subsoil and large daily effluent load
Type of treatment system best
suited:
NSW Health accredited secondary treatment system.
Reliable systems with high quality disinfected effluent
then available for beneficial reuse.
Primary treatment (septic tank) is not suited to the site because the site is not suited to subsoil absorption and there is a large daily effluent load.
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 16
RECOMMENDED EFFLUENT MANAGEMENT PRESCRIPTIONS
Effluent treatment
The following specific recommendations are made in respect of the AWTS:
1. Effluent will be treated by a NSW Health accredited system capable of achieving secondary
standard treatment, see below. The AWTS will be selected by the client in consultation with
the installer.
Table 1: NSW Health accredited secondary treatment systems
AWTS
AWTS Maintenance Envirocycle 10NR 1800688588
Bioseptic Performa 1300 658 111
Clearwater Sewage and Watertanks Biodigester II 1300 132 760
Earthsafe Environmental Earthsafe ES10PC 1300 327 847
Eco Septic Econocycle ENC 10-1, ENC 10-2 (02) 4774 1316
Everhard Industries Aqua Nova 10EP, NR, MBR10 (02) 9757 2799
Fuji Clean Fuji Clean CE 1200, CRX 1500, CE 1500 1300 733 619
Graf Plastics Australia Pty Ltd Graf Klaro EPro SBR 10EP AWTS 002 1300 131 971
Highland Tanks Pty Ltd Ultra Clear –
Ultra 10 AWTS, ST8 AWTS, ST10 AWTS
(02) 4889 8288
Icon Septech Turbojet 2000 1300 557 143
Jowa Group Biocycle Bio 7000 (08) 8381 9100
Krystel Kleer Krystel Kleer ADV 5000 (07) 3382 7666
Magnesium Tech Waterboy -
Model 10, Model S
HSTP Model 10
Magnesium Tech DMS
(07) 4055 1141
Rainflow Stormwater Solutions Gardenmaster GM7100, MBR (02) 4932 1011
Sun Coast Wastewater Management Ozzie Kleen RP10 1800 450 767
Super Treat Systems Super Treat SE 10 (02) 4422 3861
Taylex Industries Taylex DMS, ABS, Poly ABS 07 34415200
Toowoomba Tanks Super Treat 1T AST (07) 4634 3860
Wastewater Equipment Supplies Alpha Treat DP 10 (07) 3205-3666
http://www.health.nsw.gov.au/environment/domesticwastewater/Pages/default.aspx
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 17
2. The final location for the AWTS unit should be chosen by the installer, in consultation with
the client, and provide a minimum 3 m buffer from the dwelling or other buildings. An
indicative location is provided in Figure 7b.
3. The tank should also be installed so that the lid remains at least 100 mm above final ground
level to avoid stormwater entering the tank.
4. AWTS tanks should be installed in compliance with the manufacturer’s recommendations,
‘AS/NZS 3500.2:2003 Plumbing and Drainage Part 2 Sanitary Plumbing and Drainage’ and
Council requirements.
Effluent dispersal
An area of 450 m2 will be designated as the primary effluent irrigation area. Areas suitable for
effluent irrigation are identified in Figure 7b. An alternative reserve irrigation area of equal size
shall also be identified for future use if required.
Within the irrigation area, effluent can be dispersed by surface spray irrigation which is effective
for dispersing effluent on established areas of improved pasture as exist in the proposed
irrigation area.
The following specific recommendations are made in respect of effluent dispersal:
1. The effluent irrigation area of 450 m2 should be managed in two sections, one half
should be used in the warmer months, October to April, when plants can fully utilise the
applied effluent. During the period May to September, both halves should be used as
plants cannot fully utilise the moisture.
2. Effluent may be delivered by a moveable sprinkler line fitted with 5 heavy droplet (non-
aerosol) sprinkler heads at 5 metre spacings.
3. The moveable sprinkler line must be dedicated (purple) line and the sprinklers must be
dedicated (purple) sprinkler heads.
4. Surface drip systems to landscaped areas may also be used as an alternative or in
addition to the moveable sprinkler line. If both systems are fitted, they should be joined
to the treatment system via manual valves which enable either system to be isolated.
5. Surface drip irrigation areas should be divided into at least two sections connected by
a sequencing valve (automatic or manual) to enable flows to be directed independently
to the two fields. A 100-150 micron large capacity (>500cm2) disc filter should be
installed and cleaned a minimum of every three months. Air release valves should be
installed at high points in the system
6. All components are to be installed according to ‘PCA 2004 Plumbing Code of Australia’
and the conditions of consent
7. Treated effluent must be applied to growing vegetation and not bare ground.
8. Effluent needs to be applied to perennial vegetative groundcover within the area
identified in Figure 7b. Suitable grass/pasture cover will need to be maintained across
the 450 m2 area identified for effluent dispersal.
9. Grass/pasture should be slashed when it is >10 cm long
10. Alternatively, the effluent may be applied to either a landscaped area or a shelter belt of
trees and shrubs developed specifically for effluent application.
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 18
11. Species suitable for landscaping and effluent irrigation include Callistemon pallidus, C.
palludosis, Kunzea ericoides, K. parvifolia, K. phyllicoides (burgen), Leptospermum
continentale (prickly ti tree), L. multicaule, L. flavescens, L. squarrosum, Melaleuca
armillaris (honey myrtle), M. decussata, M. squamea, M. thymifolia, M. ericifolia, M.
hypericifolia, M. linariifolia.
12. Effluent is not suitable for vegetables or lawns regularly used for play and foot traffic.
13. Adequate signage should be installed to indicate that the area is being irrigated with
treated effluent.
14. Where vehicles, animals or children could access the effluent irrigation area, the effluent
irrigation area should be protected by fencing or by planting suitable shrubs around the
outside boundary.
15. The aerated wastewater treatment system must be serviced regularly to provide
adequate treatment and ensure that the irrigation system does not become clogged with
suspended solids or organic material.
16. The following buffers will be applied to the effluent irrigation area: 40m from drainage
depression, 100m from Murrumbidgee River, 3/6 m from upslope/downslope boundary,
3/6 m from upslope/downslope buildings and driveway, 250 m from bore and 15 m from
dwelling.
Special recommendations
1. The existing septic tank and subsoil absorption bed should be permanently
decommissioned. The septic tank should be pumped empty whilst the sides are being
washed down. Once empty the tank should be treated with lime and collapsed in. The
void should be backfilled with controlled fill.
2. The subsoil absorption area should continue to be treated as a potentially
contaminated site with limited human access.
General recommendations
1. Stock and vehicular access must be excluded from the irrigation area as they compact
the soil, thereby reducing the infiltration rate and water holding capacity.
2. Water conservation measures should be adopted to the greatest extent possible in the
house, particularly in relation to the high water use activities of showering, clothes
washing and toilet flushing. AAA+ plumbing appliances and fittings should be used.
Measures including use of front loading washing machines, low volume shower roses
and dual flush toilets reduce water usage by 30 to 40%.
3. Detergents low in phosphorous and sodium should be used as much as possible (see
details in appendix) in order to protect the soil’s capacity to absorb water.
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 19
Figure 7a: Property constraints
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 20
Figure 7b: Site constraints and system layout
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 21
SIZING EFFLUENT DISPOSAL AREA
Using the DIR for surface spray or drip irrigation on loam soils of 4 mm/day and design loading
of 840 L/day, the following land application areas are required to manage additional hydraulic
loading, nitrogen and phosphorous generated.
Water
balance
• Sizing based on hydraulic loading:
A = Q (l/day)/DIR (mm/day)
where A = area; Q = 840 l/day; DIR = 4 mm/day
A = 840/4 = 210 m2
Area required = 210 m2
Nitrogen
balance
• Sizing based on nitrogen balance:
A = Q(l/day) X TN (mg/l)/Ln (critical loading of TN, mg/m2/day)
where A = area; Q = 840 l/day; TN = 25mg/l (from Silver Book)
Assume 20% loss by denitrification; 25mg/l – (25 X .2) = 20mg/l
Ln = 15,000mg/m2/yr (ie 150kg/ha/yr, for introduced species)
A = 840 X 20 X 365/15,000 = 408.8 m2
Area required = 450 m2
Phosphorous
balance
• Sizing based on phosphorous balance
A = Pgen/( Puptake + Psorb) [P sorption capacity in upper 50cm & 50 year design
period]
P gen = 10mg/l X 840 X 365 X 50 = 153.3kg
P uptake = 4.4mg/m2/day X 365 X 50 = .080kg/m2
P sorb = 2,746kg/ha = .275kg/m2
A = 153.3/(.08+ .275) = 431.8m2
Area required = 450 m2
Design
effluent
disposal
area
Therefore, a land application area of 450 m2 will account for phosphorous,
nitrogen and hydraulic loading applied based on usage patterns associated
with the 3-bedroom main dwelling plus separate 2-bedroom accomodation.
An allowance of a reserve land application area will double this area to
900 m2.
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 22
SITE AND SOIL LIMITATION ASSESSMENT The following two limitation tables are a standardised guide to the site and soil characteristics
which may limit the suitability of the site for effluent disposal and which would require attention
through specific management practices. The tables have been reproduced from On-site Sewage
Management for Single Households (tables 4 and 6, Anon, 1998). The highlighted categories
represent site and soil conditions of the land covered in this report. The tables show that the
land designated for effluent application has slight to moderate limitations, but no severe
limitations.
Site limitation assessment
Site feature Relevant
system
Minor
limitation
Moderate
limitation
Major limitation Restrictive
feature
Flood
All land
application
systems
> 1 in 20 yrs. Frequent, below 1
in 20 yrs
Transport in
wastewater off
site
potential All treatment
systems
components
above 1 in 100
yrs.
Components
below 1 in 100
yrs.
Transport in
wastewater off
site, system
failure
Exposure All land
application
systems
High sun and
wind exposure
Low sun and
wind exposure
Poor evapo-
transpiration
Surface
irrigation
0-6 6-12
>12 Runoff, erosion
potential
Slope % Sub-surface
irrigation
0-10 10-20
(surface
drip)
>20 Runoff, erosion
potential
Absorption 0-10 10-20 >20 Runoff, erosion
potential
Landform All systems Hillcrests,
convex side
slopes and
plains
Concave
side slopes
and foot
slopes
Drainage plains
and incised
channels
Groundwater
pollution hazard,
resurfacing
hazard
Run-on and
seepage
All land
application
systems
None-low Moderate High, diversion
not practical
Transport of
wastewater off
site
Erosion
potential
All land
application
systems
No sign of
erosion
potential
Limited
signs of
erosion
Indications of
erosion e.g. rills,
mass failure
Soil degradation
and off-site
impact
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 23
Site feature Relevant
system
Minor
limitation
Moderate
limitation
Major limitation Restrictive
feature
Site
drainage
All land
application
systems
No visible signs
of surface
dampness
Visible signs of
surface
dampness
Groundwater
pollution hazard,
resurfacing
hazard
Fill All systems No fill Fill present Subsidence
Land area All systems Area available Area not available Health and
pollution risk
Rock and
rock outcrop
All land
application
systems
<10% 10-20% >20% Limits system
performance
Geology All land
application
systems
None Major geological
discontinuities,
fractured or
highly porous
regolith
Groundwater
pollution hazard
1192 WALLAROO ROAD WALLAROO
SOIL AND WATER 24
Soil limitation assessment
Soil feature Relevant
system
Minor
limitation
Moderate
limitation
Major
limitation
Restrictive feature
Depth to
bedrock
Surface and
sub surface
irrigation
> 1.0 0.5-1.0 < 0.5 Restricts plant growth
or hardpan (m) Absorption > 1.5 1.0-1.5 < 1.0 Groundwater pollution
hazard
Depth to
seasonal water
table (m)
Surface and
sub surface
irrigation
> 1.0 0.5-1.0 < 0.5 Groundwater pollution
hazard
Absorption > 1.5 1.0-1.5 < 1.0 Groundwater pollution
hazard
Permeability Surface and
sub surface
irrigation
2b, 3 and 4 2a, 5 1 and 6 Excessive runoff and
waterlogging
Class Absorption 3, 4 1, 2, 5, 6 Percolation
Coarse
fragments %
All systems 0-20 20-45 >40 Restricts plant
growth, affects trench
installation
Bulk density
(g/cc)
SL
L, CL
C
All land
application
systems
< 1.8
< 1.6
< 1.4
> 1.8
> 1.6
>1.4
restricts plant growth,
indicator of
permeability
pH All land
application
systems
> 6.0 4.5-6.0 - Reduces plant growth
Electrical
conductivity
(dS/m)
All land
application
systems
<4 4-8 >8 Restricts plant growth
Sodicity (ESP) Irrigation 0-
40cm;
absorption 0-
1.2mtr
0-5 5-10 > 10 Potential for
structural degradation
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Soil feature Relevant
system
Minor
limitation
Moderate
limitation
Major
limitation
Restrictive feature
CEC
mequiv/100g
Irrigation
systems
> 15 5-15 < 5 Nutrient leaching
P sorption
kg/ha
All land
application
systems
> 6000 2000-6000 < 2000 Capacity to
immobilise P
Aggregate
stability
All land
application
systems
Classes 3-8 class 2 class1 Erosion hazard
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APPENDIX 1: SOIL PROFILE DESCRIPTIONS
Soil Profile 1 – Building Envelope Area
Soil classification Depth
(cm)
Properties
Brown Chromosol 0-40
40-80
A1 Light brown sandy loam, moist and friable, weak to
massive structure, no coarse fragments, strong break to
B Red/orange sandy light to medium clay, moist and firm,
moderate structure, no coarse fragments, degrades to sandy clay
granite saprolite material
Figure 8: Soil Profile 1 – Building Envelope
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Soil Profile 2 – Effluent Disposal Area
Soil classification Depth
(cm)
Properties
Brown Chromosol 0-45
45->100
A1 Light brown sandy loam, moist and friable, weak to
massive structure, no coarse fragments, strong break to
B Red/orange sandy light to medium clay, moist and firm,
moderate structure, no coarse fragments, degrades to sandy clay
granite saprolite material
Figure 8: Soil Profile 2 – Effluent dispersal area
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APPENDIX 2: SUPPORTING INFORMATION
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APPENDIX 3: SITE CLASSIFICATION INFORMATION
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