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

[email protected]

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.

mailto:[email protected]


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).


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.


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)


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


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


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


SOIL AND WATER 10

Figure 5: Looking south east across the proposed effluent irrigation area


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


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.


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.


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


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.


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


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.


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.


SOIL AND WATER 19

Figure 7a: Property constraints


SOIL AND WATER 20

Figure 7b: Site constraints and system layout


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


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


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.


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


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


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


SOIL AND WATER 25

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


SOIL AND WATER 26

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


SOIL AND WATER 27

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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SITE CLASSIFICATION ON-SITE SEWAGE MANAGEMENT REPORT …

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