ONSITE WASTEWATER REPORT

DPS YASS Pty Ltd STATEMENT OF ENVIRONMENTAL EFFECTS REF: 4044_SEE1 – MODIFICATION TO DA200030, NANIMA

21

APPENDIX B ONSITE WASTEWATER REPORT

838 Murrumbateman Road

NANIMA NSW 2618

Lot 1 DP 1213153

Version 5

13 August 2021

FRANKLIN CONSULTING

AUSTRALIA PTY LIMITED

abn 59 611 394 953 acn 611 394 953 po box 837 canberra act 2601 p 02 6179 3491 m 0490 393 234 [email protected] www.soilandwater.net.au

ON-SITE SEWAGE

MANAGEMENT

REPORT

Our Company

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, CEnvP

John Franklin has over 30 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.

This experience includes providing extensive soil and water management advice to land

holders, businesses, State and Local Governments and the urban / rural residential

development sector across the region.

John has detailed knowledge of water resource policy and developed the NSW Farm

Dams Policy in 1999 for the Department of Land and Water Conservation and provided

strategic support and direction to the NSW water reform process.

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 Recommendations and analysis provided in this report are based on a site inspection undertaken by Soil and Water, and information provided by the client. Soil and Water takes no responsibility for actions taken, or changes made after the date of the site inspection that impact on any of the constraints and recommendations made in this report, nor the accuracy of details provided by the client.

mailto:[email protected]

CONTENTS

SUMMARY RECOMMENDATIONS ......................................................................................................... 1

REPORT SCOPE AND TECHNICAL REFERENCES ................................................................................. 2

SITE INFORMATION ............................................................................................................................... 3

LANDSCAPE CHARACTERISTICS .......................................................................................................... 6

SITE ASSESSMENT................................................................................................................................. 7

SOIL ASSESSMENT .............................................................................................................................. 10

SYSTEM SELECTION – Shed ............................................................................................................... 11

EFFLUENT MANAGEMENT PRESCRIPTIONS – Shed Site ................................................................. 12

SIZING EFFLUENT DISPOSAL AREA – Shed Site ............................................................................... 16

SITE AND SOIL LIMITATION ASSESSMENT ........................................................................................ 17

APPENDIX 1: SOIL PROFILE DESCRIPTIONS ..................................................................................... 21

APPENDIX 2: SUPPORTING INFORMATION ....................................................................................... 22

838 Murrumbateman Road Nanima

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SUMMARY RECOMMENDATIONS

Version 5 Amendments: This report amends previous versions with a revised location for the shed,

and a revised effluent management system associated with this new shed

location.

Reference to the effluent management system associated with the existing

dwelling has been removed and this report only refers to the proposed shed

in the revised location

The effluent management system proposed for the shed has been designed

to have adequate capacity to service an adjacent dwelling which may be

constructed in the future (subject to separate Council approval).

Development: The proposal involves the construction of a shed on Lot 1 DP 1213153 at 838

Murrumbateman Road, Nanima, NSW. The shed will include a kitchenette

and toilet facilities. The design of the effluent management system includes

adequate capacity to service a future 4–bedroom dwelling which may be

constructed on an adjacent site (Subject to Council Approval).

Site: The site is extensively cleared around the shed site with a groundcover of

introduced and native pasture species. There is scattered remnant native

vegetation across the property. Historic land use has been grazing.

The modified shed site is on a moderate northerly slope adjacent to the

eastern boundary.

The property is drained by overland flow and 1st and 2nd Order Streams

which include numerous farm dams and flow south to north across the lot.

The property is surrounded by rural properties on all sides.

Recommended Treatment Systems: The site and soil conditions associated with the proposed

shed are well suited to secondary treatment system (Aerated Wastewater

Treatment System [AWTS]).

Recommended Dispersal System: There is an adequate area in proximity to the shed site

which is suitable for the surface spray irrigation of secondary treated and

disinfected effluent in accordance with the prescriptions contained in this

report.

Dispersal Sites: The effluent dispersal areas of 350m2 is located immediately downslope of

the proposed shed, refer Figures 5a-b.

The shed effluent dispersal site is outside buffers from the shed and

driveways (6m).

Constraints: The main site constraints are the buffers required from proposed building,

driveway and drainage depressions, refer Figures 5a-b.


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REPORT SCOPE AND TECHNICAL REFERENCES The report assesses land in the vicinity of the proposed development to identify areas suited to on-site effluent disposal. 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 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. Foundation Maintenance and Footing Performance -A Homeowner’s Guide (CSIRO, 1991)

Soil Landscapes of the Canberra 1:100,000 Sheet. Jenkins B.R. (2000) DLWC

Yass Valley Local Environment Plan (2013)


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SITE INFORMATION

Local Government Area: Yass Valley Council

Address/locality: Lot 1 DP 1213153 at 838 Murrumbateman, NANIMA, NSW 2618

Owner/Developer: TP Dynamics

Block Configuration: Location and configuration shown at Figures 1 & 2. See also photos

at Figures 3-4.

Figure 1: Site locality


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Figure 2: Block configuration

Intended water supply: Non-reticulated – roof catchment – tank storage for domestic water.

Expected wastewater load (volume in litres/day, AS 1547:2012):

Shed site: The effluent management system design for the shed has been based on an equivalent 4-bedroom dwelling with non-reticulated water supply, which will generate a design wastewater load of 600L/day. The design will provide adequate capacity for the facilities proposed in the shed, plus the connection of an adjacent 4-bedroom dwelling which may be constructed in the future (subject to Council approval).

Design wastewater load = 600 litres per day

Local experience: Most secondary treatment and surface spray irrigation systems work effectively on moderately sloping land with shallow soils. Systems commonly malfunction due to lack of ongoing maintenance. System to be maintained regularly, in accordance with council regulations and prescriptions in this report.


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Figure 3: Looking northeast from the Shed

Figure 4: Looking north west across Shed building envelope


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LANDSCAPE CHARACTERISTICS Landscape Rolling to steep hills with elevation between 600 and 750 m. Some timbered hill tops and crests with

remainder cleared grazing country on moderate to steep slopes. Bands of outcropping rock on

ridgelines and hill tops with loose rocks common on side slopes.

Minor non-permanent 1st and 2nd Order Streams and defined drainage depressions on lower slopes

with some water supply and erosion control dam structures.

Soils Detailed soil profile descriptions are provided in Appendix 1 of this report.

Soils range from shallow well-drained Rudosols on hills crest and higher side slopes to moderately

deep Brown to Red Chromosols on lower side slopes. Broad flat crests area can include areas of

moderately deep Kandosol soils.

Soils are part of the Bywong Soil Landscape Unit1. The representative analytical shows a moderate

phosphorous sorption level, non-saline subsoils and low exchangeable sodium. As such the soils are

free of any significant chemical limitations to effluent dispersal. The main soil constraint to effluent

dispersal is the variable limited soil depth including some outcropping rock across the lot.

1 Soil Landscapes of the Canberra 1:100,000 Sheet. Jenkins B.R. (2000) DLWC


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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.

The local climate is therefore well suited for the surface irrigation of secondary treated effluent.

Rainfall water balance: Yes

Land application area calculated: Yes.

Wet weather storage calculation: NA

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: Yes

Exposure The site is extremely exposed with no shading or topographical shelter. General aspect for the dwelling is a moderate to steep north facing slope. The shed site is on the upper slopes and has no shading.

Exposure in the vicinity of the shed effluent disposal area is suited to surface spray irrigation.

Slope Slopes running along the top of the ridge crest where the dwelling is to be constructed are relatively

flat (<5%) with suitable areas for construction and effluent dispersal. Upper side slopes in the vicinity

of the shed are moderately sloping with grades up to 12%.

Slopes are a minor constraint to the disposal of secondary treated effluent through surface spray

irrigation.

Landform Slope form of the shed effluent disposal site is divergent, resulting in runoff spreading out rather

than concentrating.

The divergent landforms in the proposed effluent disposal site is suited to surface spray irrigation.

Run-on Limited local run-on water will impact the shed effluent disposal site due location on upper slopes

and convex topography.

The effluent disposal area will not be significantly impacted by upslope run-on water.


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Seepage No seepage was evident on the property.

Erosion potential Soils are susceptible to erosion and there is evidence of historical gully erosion in the drainage depressions on the property. Moderate slopes associated with upper slope shed effluent dispersal area, combined with adequate groundcover, will limit erosion potential. The shed effluent disposal areas will be protected from erosion by the maintenance of good levels of vegetative groundcover. Where adequate groundcover (>80%) cannot be achieved prior to effluent irrigation then the area will need to be mulched.

Site drainage Site drains through overland surface flow and through 1st and 2nd Order Streams (including dams)

which flow south to north across the property.

The proposed shed effluent disposal area will be located outside the 40m buffer distance required

from drainage depressions and dams located on the lot.

Fill No fill proposed for the shed effluent disposal area.

Groundwater Horizontal distance to groundwater well used for domestic supply:

There are no bores within 500m of the House or Shed sites.

Groundwater vulnerability map category:

https://www.legislation.nsw.gov.au/maps/a3c0cc0b-7472-ceb7-b44a-f766ca80b78d/8710_COM_CL2_005_160_20130423.pdf

No domestic groundwater wells are known in the vicinity. The block is mapped on the Yass Valley LEP (2013) Groundwater Vulnerability map – Sheet CL2_005.

Bores in area and purpose: The closest bore to the shed site (GW400395) is located approximately 1200 m west of the proposed effluent disposal site. It is registered as a stock, farming, irrigation, domestic bore. The bore is 91.5 m deep with water bearing zones at 40.0-40.5m, 61.0-61.5m, 83.0-83.5m, 85.0-85.5m. The effluent management practices proposed on the property will not impact these bores or the groundwater aquifer due to:

• Spatial separation of >1200m





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https://realtimedata.waternsw.com.au/

• Vertical separation of >40m

• low transmissivity of fractured rock

aquifer systems

• low application rate of secondary treated and disinfected effluent to the near surface.

Buffer distance from treatment system to: Perennial rivers and creeks: NA Drainage depressions: 40m Other sensitive environments: 40m (dams) Dwelling: NA Boundary of premises: 3m / 6m (upslope/downslope boundaries) Swimming pools: NA Buildings: 3m / 6m (upslope/downslope buildings)

Is there sufficient land area for: Application system including buffers: Yes – refer Figures 5a-b identifies the land suitable for

effluent disposal associated with the shed. Reserve application system: Yes - refer Figures 5a-b

Surface rock and outcrop: Loose cobble is common across the site but represents less than 2.

Rock is not a constraint to effluent disposal for the shed.

https://realtimedata.waternsw.com.au/


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SOIL ASSESSMENT

Depth to bedrock or hardpan: 0.5->1.0m (variable)

Depth to high soil water table: >1.0 m

Hydraulic loading rate Soil texture: Soil structure:

Subsoil Absorption Permeability (from table L1 of AS1547:2012):

Recommended design loading rate for subsoil absorption system

(from table L1 of AS1547:2012):

Clay Loam Weak to Moderate 0.5-1.5m/day 10mm/day

Coarse fragments: <5%

Bulk density* 1.3-1.7 t/m3 in topsoil, 1.5 t/m3 in subsoil

PH field*: 4.0 in topsoil, 5.5 in subsoil

Electrical conductivity dS/m2 0.17 in topsoil, 0.04-0.06 in subsoil

Exchangeable sodium 13 2 in topsoil, 9 in subsoil

Cation exchange capacity (mequiv/100g)*: 29.8 in topsoil, 6.6 in subsoil

Phosphorous sorption capacity mg/kg4: 113 in topsoil, 654 in subsoil

Geological feature Discontinuities: Fractured rock

None None

Soil landscape reference Bywong

Dispersiveness EAT class: 2(2) in topsoil, 2(1) in subsoil

2 extrapolated from Jenkins (2000) Soil Landscapes of the Canberra 1:100,000 Sheet. DLWC 3 ibid 4 ibid


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SYSTEM SELECTION – Shed

Consideration of connection to centralised sewerage system

Distance: Potential for future connection: Potential for reticulated water:

>5 kms None None

Type of land application system best suited

Justification:

NSW Health accredited secondary treatment system. Suited to site and soil conditions.

Type of treatment system best suited

Justification:

Surface irrigation Suited to site and soil conditions, enables effluent to be utilized in maintaining landscaping in water constrained environment.


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EFFLUENT MANAGEMENT PRESCRIPTIONS – Shed Site Effluent treatment

The following site-specific recommendations are made in respect of the AWTS: 1. Effluent will be treated by a NSW Health accredited treatment system producing

secondary standard and disinfected effluent, refer below link to accredited systems:

http://www.health.nsw.gov.au/environment/domesticwastewater/Pages/default.aspx 2. An indicative location for the AWTS unit is provided in Figure 5. 3. AWTS should be managed in compliance with the manufacturer’s

recommendations and Council requirements.

Effluent dispersal

An area of 350 m2 will be designated as the primary effluent irrigation area. Areas suitable for effluent irrigation are identified in Figure 5. An alternative reserve irrigation area of equal size shall also be identified for future use if required. Within the nominated irrigation area effluent will be dispersed by surface spray irrigation which is effective for dispersing effluent on the established areas of pasture as exist on the site. The following site-specific recommendations are made in respect of effluent dispersal:

1. The effluent irrigation area of 350 m2 should be managed in 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. The moveable surface spray irrigation line should be moved regularly to provide for even distribution of effluent.

3. Treated effluent must be applied to growing vegetation and not bare ground. If 100% groundcover is not achievable the irrigation area should be mulched to achieve groundcover and reduce erosion risk and promote the establishment of suitable pasture species.

4. Grass/pasture should be slashed when it is >10 cm long 5. Effluent is not suitable for vegetables or lawns regularly used for play and foot

traffic. 6. Adequate signage should be installed to indicate that the area is being irrigated

with treated effluent. 7. 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.

8. 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.

9. The following buffers will be applied to the effluent irrigation area: 3/6 m from upslope/downslope buildings and driveways, 40 m from drainage depressions (including dam) and 250 m from bores.

General

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.


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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.


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Figure 5a: Site Constraints and System Layout – Shed


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Figure 5b: Site Constraints and System Layout – Inset Map


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SIZING EFFLUENT DISPOSAL AREA – Shed Site Water balance

Using the Design Loading Rate (DLR) for absorption bed on loam soils of 3.5 mm/day and adopting a design loading of 600/day, the following land application areas are required to manage additional hydraulic loading, nitrogen and phosphorous generated:

• Sizing based on hydraulic loading:

A = Q (l/day)/DIR (mm/day) where A = area; Q = 600 l/day; DIR = 3.5 mm/day A = 600/4 = 171 m2 Area required = 200 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 = 600 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 = 600 X 20 X 365/15,000 = 292 m2

Area required = 300 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 600 X 365 X 50 = 109.5kg P uptake = 4.4mg/m2/day X 365 X 50 = .080kg/m2

P sorb = 2,250kg/ha = .225kg/m2

A = 109.5/(.08+ .25) = 332 m2 Area required = 350m2

Design effluent disposal area

Therefore, a land application area of 350 m2 will account for phosphorous, nitrogen and water applied based on estimated connections and usage patterns associated with the construction of the shed (based on an equivalent 4-bedroom house). An allowance of a reserve land application area will double this area to 700 m2.


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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


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Site feature Relevant

system

Minor

limitation

Moderate

limitation

Major limitation Restrictive

feature

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

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


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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;

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

absorption 0-

1.2mtr

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– Effluent irrigation area downslope of shed site

Soil classification Depth

(cm)

Properties

Rudosol 0-10

10-20

20-50

>50

A1 medium brown, weak structure, gravel (5-10%) silty loam, weak to

massive structure, dry friable consistence, gradational colour change to

A2 light grey yellow brown clay loam, gravel), weak to massive structure,

dry friable consistence, gradual colour and textural boundary to

B1 pale grey to yellow light clay loam, (5-10% gravel), slightly moist firm

consistence, weak to structure, gentle gradation to

C light grey light clay loam interspersed with decomposing parent

material

Figure 5: Soil Profile 2 – Location shed site (Refer Figure 5)

NB: Soil profiles are presented as expanded profiles (expansion factor approximately X2)


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APPENDIX 2: SUPPORTING INFORMATION


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