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Trent Parmenter Re: 96 Coomba Road Charlotte Bay, NSW 2428 (via email)

Ref: Letter_2449_003

29 January 2020

On-site Wastewater Management Plan for proposed Animal Boarding Facility at 96 Coomba Road, Charlotte Bay NSW

Whitehead & Associates (“W&A”) were engaged by Trent Parmenter (the “Client”) to prepare an

Onsite Wastewater Management Plan for a proposed animal boarding facility at 96 Coomba

Road, Charlotte Bay NSW (the “Site”). The Site is identified as Lot 120 in DP848596 and is

zoned R5 ‘Large Lot Residential’ under the Great Lakes Local Environmental Plan (LEP, 2014).

It is understood that the Client is proposing to prepare a development application (DA) for the

construction of an animal (up to 30 dogs) boarding facility on the Site. The subject lot forms part

of an earlier 4-lot subdivision (DA-445/2015) and the residual property will be approximately

1.827ha in area (see Figure 1, Appendix A). The property contains an existing residential

dwelling and several smaller buildings (sheds etc.) in a cleared area to the north. The property

is serviced by on-site (tank) water supply and no sewer service is available.

The Site is identified as being bushfire prone and may also contain sensitive vegetation. The

property is located within proximity to an identified ‘wetland’ area of Wallis Lake and several

dams are located on and adjacent to the property. The Site is not located within a water

catchment area. The Site is located within the ‘coastal zone’ as identified in the Coastal

Management Act (2016) and is approximately 380m south of Wallis Lake. As such, the Site falls

under the requirements of State Environmental Planning Policy (Coastal Management) 2018.

MidCoast Council (“MCC” or “Council”) is proposing to adopt a comprehensive Development

Assessment Framework (DAF) for onsite sewage management (OSSM), which sets out

required standards for investigation, acceptable solutions and minimum standards for sewage

management in unsewered areas of the MidCoast (formerly Great Lakes) Local Government

Area (LGA). The draft MCC DAF (2018) identifies each allotment within the LGA as having Low,

Moderate or High hazard for OSSM.

Council have advised that the Site is considered a ‘High hazard’ allotment for non-domestic

development. The following table presents the minimum standards required by the draft MCC

DAF (2018) for a ‘High hazard’ non-domestic Wastewater Management Report (WMR).

Whitehead & Associates Environmental Consultants Environmental Consultants

mailto:[email protected]

http://www.whiteheadenvironmental.com.au/

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DAF Minimum Standards for WMR (High Hazard – Non-domestic)

Report Element Minimum Standard Completed

Introduction and Background

Name, contact details and qualifications of author(s). ✓

Site location and owner. ✓

Allotment size (m² or ha). ✓

Proposed / existing water supply. ✓

Description of proposed facility (including equivalent persons). ✓

Availability of sewer. ✓

Site and Soil Assessment

Broad overview of locality and landscape characteristics. ✓

Details of the date and time of assessment in addition to statements confirming the methods used to complete the assessment.

✓

Site assessment that considers all parameters listed in Table 31 of the DAF in accordance with AS/NZS 1547:2012.

✓

Detailed review of available published soils information for the Site. ✓

Soil assessment that considers all parameters listed in Table 31 of the DAF in accordance with AS/NZS 1547:2012.

✓

Where multiple soil facets are present the site plan should show the approximate boundary between facets.

N/A

Detailed explanation of the implications of observed site and soil features for system design and performance.

✓

Assessment of the existing condition of the receiving environment and sensitivity to on-site system impacts.

✓

System Selection

Summarise potential treatment and land application systems considered including advantages and limitations.

✓

Preliminary design calculations for a minimum of 2-4 options. ✓

Brief statement justifying selection of treatment and land application system.

✓

Design

Detailed wastewater characterisation (quality and quantity) including temporal variation using existing data for the subject site or similar facilities.

✓

Establishment of clear, site specific design criteria based on typical or published performance.

✓

Process design in accordance with Tchobanoglous and Burton (2003) or Crites and Tchobanoglous (1997) detailing the rationale, assumed

performance and capacity to manage design flows and loads. Process performance should be supported by published data or information that demonstrates the suitability of the process to the site and development.

N/A

Daily water, nutrient and pathogen modelling to size any land application areas (see MCC Technical Manual).

✓

Hydraulic design of collection, treatment and land application components to demonstrate viability of the process.

Design drawings (CAD or similar) and specifications for all system components.

Site Plan

Survey plan. ✓

Proposed allotment boundaries, dimensions and area; ✓

Location of existing buildings, swimming pools, paths, groundwater bores, dams and waterways;

✓

Location of exclusion zones (e.g. setback distances and unsuitable site and soil conditions);

✓

Location of all system components and any reserve areas to clearly demonstrate viability;

✓

Half metre elevation contours; and ✓

Location of existing and proposed drainage pipework (centreline). ✓

Off-site Impacts (where required)

Summary of approach taken and confirmation of compliance with the Minimum Standards documented in Section 3.2.4.

✓

Methodology documenting the basis and source of input data including reference to site specific data, published information or the Technical Manual to justify use.

✓

Results demonstrating compliance with local water quality objectives and adequate management of health risks as defined and demonstrated in Table 22 and Section 10 of the Technical Manual.

✓

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Brief discussion of long-term risks to health and environment and recommended management measures to address impacts.

✓

Appendices

Soil bore logs for all test pits. ✓

Raw laboratory results for soil analysis. ✓

All design calculations and assumptions including screenshots of cumulative impact spreadsheets/models.

✓

1 Introduction

This WMR was prepared by Elise Powning. Elise is an experienced Environmental Consultant

with W&A, holding a B.Sc. from the University of Newcastle (2016). Elise has completed the On-

Site Wastewater Management professional short-course with the Centre for Environmental

Training (CET) and has prepared WMR’s for many residential and commercial Sites across the

Hunter, Central Coast, Port Stephens and Mid North Coast regions.

This WMR has been undertaken in reference to the assessment and design principles of:

AS/NZS 1547:2012 On-site Domestic Wastewater Management (Standards Australia /

Standards New Zealand, 2012);

Environment & Health Protection Guidelines: On-site Sewage Management for Single

Households (Department of Local Government, 1998);

MidCoast Council (2018) Draft On-site Sewage Development Assessment Framework

(DAF). Revision 1, dated 16 November 2018; and

MidCoast Council (2019) Draft On-site Sewage Management Technical Manual.

Revision 0, dated 22 February 2019.

The following table presents information on the Site investigated.

Feature Description

Site Address 96 Coomba Road, Charlotte Bay NSW

Local Government Area MidCoast Council

Land Zoning R5 Large Lot Residential (LEP, 2014)

Lot Size (ha) ~1.827

Sewer Connection Available (within 75m) No

Potable Water Supply On-site (tank) water supply

2 Site and Soil Assessment

A Site investigation was undertaken by Elise Powning of W&A on the 12th September 2019. The

following tables present the results of our site and soil investigation.

A description of the Site physical constraints and the degree of limitation they pose to OSSM is

provided in the table below. Reference is made to the rating scale in NSW DLG (1998) and,

where appropriate, the draft MCC DAF (2018).

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SITE ASSESSMENT

Parameter Data / Observation Reference Classification /

Outcome

Climate Temperate climate with mean annual rainfall of 1,225mm and mean annual evaporation of 1,424mm.

Forster – Table 14 draft MCC

DAF Technical Manual (2019)

Minor limitation

Hydraulic (daily) modelling attached: Yes

per draft MCC DAF (2018) procedure

Nutrient (daily) modelling attached: Yes

Land Application Area sizing attached: Yes

Wet weather storage requirement: No

Flooding

Council Online Mapping

indicates the property is not flood affected

Minor limitation

Land Application Area above 1:20 ARI flood level: Yes

Land Application Area above 1:100 ARI flood level: Yes

Electrical components above 1:100 ARI flood level: Yes

Exposure The majority of the Site is heavily vegetated with a cleared area to the north, along a ridgeline.

Moderate limitation

Slope ~3-8% slope on the ridgeline grading to >30% slope on the side slopes.

Minor to Major limitation

Landform Convex divergent slope configuration with undulations.

Minor limitation

Run-on and Seepage

No run-on or up-slope seepage observed in the vicinity of the effluent management area (EMA) at the time of Site inspection.

Stormwater from upslope areas and roof run-off must be directed away from the EMA.

Mitigation measures recommended (see Section 7.3).

Minor limitation

Erosion Potential

Good vegetation cover across majority of the Site, with minor erosion evident on cleared surfaces.

Address using erosion and sediment controls during construction and revegetation of land application area (LAA) using turf.

Minor limitation

Site Drainage

Moderately well drained. No signs of surface saturation; however, minor mottling was observed throughout the soil profile, indicating imperfect drainage at times during the climate cycle.

Minor limitation

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Fill None observed or apparent. Minor limitation

Groundwater

No shallow groundwater (GW) encountered during soil survey.

NSW Office of Water GW bore registry indicates no bores are situated within 500m of the Site. The NSW DLG (1998) recommended 250m buffer distance to domestic GW bores can therefore be achieved within the identified EMA.

Permanent GW expected to be >1m based on local conditions and test pit excavations.

Minor limitation

Flood Potential

Several dams are located on and adjacent to the Site, with numerous associated intermittent drainage features. Wallis Lake is located approximately 380m from the Site’s northern boundary.

A review of the ‘Wallis Lake Foreshore (Floodplain) Risk Management Study and Plan’ (WMA Water, 2014) indicates that the maximum 1% AEP flood level for Wallis Lake is 2.7m AHD.

The properties lowest elevation is ~21.5m AHD and is therefore not considered to be flood affected.

Minor limitation

Buffers Applicable

Permanent surface waters (100m): Yes Achievable

Intermittent creeks, drainages and dams (40m):

Yes Achievable

Domestic groundwater wells and bores (250m):

N/A

Other sensitive receptors: N/A

Lot boundaries (6m if EMA downslope-12m if EMA upslope):

Yes Achievable

Buildings, driveways and swimming pools (3m if EMA downslope-6m if EMA upslope):

Yes Achievable

Limiting horizon (GW, bedrock etc.) (0.6m): No

Rock floaters encountered at ~350-800mm.

Mitigation recommended (see Section 7.1.1).

Surface Rock / Outcrop

Surface rocks and rock outcrops were encountered during the Site investigation.

Moderate limitation

Effluent Management Area (EMA)

Approximately 3,066m² of available EMA is identified on the property.

Minor limitation

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Concluding Remarks

No major constraints to OSSM exist at the Site; with the exception of slope which exceeds 20% in parts of the available EMA. Identified limitations can be successfully avoided and/or mitigated by design.

SOIL ASSESSMENT (Physical)


Outcome

Soil Depth ~350-800mm.

Refusal on rock floaters. Moderate to Major limitation

Soil Profile

A: 0-150/300mm, weak to moderately structured sandy clay loam (Cat 4).

B: 150/300->350/800mm, weak to moderately structured sandy clay loam to sandy clay (Cat 4/5).

Moderate limitation

Depth to Water Table

Shallow (episodic) water table not encountered.

Minor mottling observed throughout the soil profile, indicating restricted vertical drainage within Site soils during periods of high rainfall or extended wet weather.

Minor limitation

Coarse Fragments (%)

~5-15% (20mm-100mm). Minor limitation

Soil Permeability

0.06-0.12m/day (indicative).

Based on moderately

structured sandy clay (Cat 5)

Moderate to Major limitation

Modified Emerson Aggregate Class (EAT)

Topsoil: 3(1), 3(2) and 8

Subsoil: 3(1) and 3(3) Minor to Moderate limitation

Soil Landscape

Soil landscape data is not available for the Charlotte Bay local area. Soil data available on eSPADE from individual soil surveys at Charlotte Bay have similar soil characteristics to soils found on the Site. This data and information from the Soil and Land Resources of Central and Eastern NSW indicate that the Site is located on the Myall (mfs) series comprising well-drained ‘bleached’ Tenosol / Lithosol soils.

eSPADE (SALIS)

Concluding Remarks

Site soils are characterised by sandy clay loam topsoils to ~150-300mm, underlain by sandy clay subsoils to >350-800mm. Soil structure is typically weak to moderate.

Based on identified soil characteristics a (maximum) design loading rate (DLR) of 10mm/day is allowable for (secondary) subsurface absorption systems with reference to Table L1 in the AS/NZS 1547:2012 for Category 5 soils. Identified soil permeability limitations will be addressed through

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conservative LAA sizing and design.

Soil conditions are generally moderate to good in the preferred EMA; however, available soil depth limitations are present. Potential negative consequences associated with soil depth can be mitigated by either deep ripping and removing rock floaters or (if needed) raising the land application system above the natural ground level to increase available separation to the limiting condition (see Section 7.1.1).

SOIL ASSESSMENT (Chemical)


Outcome

pH Topsoil: 4.7-5.3

Subsoil: 5.0-5.6

Moderate to very strongly acid

Moderate limitation

EC (ECe) Topsoil: 0.11-0.40

Subsoil: 0.06-0.25 Non-saline Minor limitation

ESP (%) 6.1 (marginally) Sodic

From soil laboratory analysis

Moderate limitation

CEC (me/100g) 3.3 Very low fertility Major limitation

P-sorption (mg/kg)

207 (3,100kg/ha) Moderate Moderate limitation

Concluding Remarks

The pH, exchangeable sodium percentage (ESP) and cation exchange capacity (CEC) of the Site soils pose a moderate to major constraint to OSSM; however, potential negative consequences can be mitigated through soil improvement recommendations (see Section 7.1.2).

3 Wastewater Generation

3.1 Site Facilities

Wastewater will be generated from multiple activities on-site. The main facilities include:

Three (3) bedroom residential dwelling and studio (4-bedrooms total);

Staff/public toilet facility (WC and hand basin);

Staff room (sink and food preparation);

Kennel kitchen/storage/utility area (sink, food preparation and laundry);

Kennel grooming area (wash tub/basin); and

Kennels and communal play area.

Wastewater generated by the Site can be broadly categorised as domestic wastewater (i.e.

from toilets, showers, kitchens etc.), greywater (i.e. from animal washing, laundry etc.) or wash-

down wastewater (from kennels and communal play area).

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3.2 Wastewater Quality

3.2.1 Domestic Wastewater and Greywater

Domestic wastewater can be separated into two different components, blackwater (toilet) and

greywater (kitchen, laundry and shower), which have different physical and chemical

characteristics.

The contaminants in domestic wastewater have the potential to create undesirable public health

concerns and pollute waterways unless managed appropriately. As a result, domestic

wastewater must be treated to remove the majority of pollutants and enable attenuation of the

remaining pollutants through soil processes and plant uptake.

Domestic wastewater and greywater generated by the facility are expected to have

characteristics similar to that described in the table below; which incorporates information taken

from the NSW DLG (1998).

Parameter Loading Greywater % Blackwater %

Daily Flow 65 35

Biochemical Oxygen Demand 200-300mg/L 35 65

Suspended Solids 200-300mg/L 40 60

Total Nitrogen 20-100mg/L 20-40 60-80

Total Phosphorus 10-25mg/L 50-70 30-50

Faecal Coliforms 103 – 10

10cfu/100ml Medium – High High

3.2.2 Kennel and Communal Play Area Wash-down Wastewater

It is recommended that a ‘dry’ cleaning approach is used for cleaning the kennel areas of the

facility, in line with industry standards. This would include disposal of faeces in the garbage,

with a daily mop down and pressure wash of each shelter to minimise unnecessary additional

wastewater production.

Wash-down water may contain animal faecal matter (very minimal) plus dirt, grit and hair.

Sanitiser and/or disinfectant are used in the kennels during each wash-down, so wash water will

also contain some traces of these cleaning products. Faecal contamination of wash-down water

is expected to be very low, because shelter management practices require that faeces are

swept up and disposed of in the garbage, rather than hosed away.

Animal (particularly dog) waste is notoriously difficult to treat using conventional sanitary

approaches; hence, it is important that solids (faeces etc.) are largely removed from the waste

stream before treatment. By directing all wash-down water through an appropriate grit/hair

collector or trap, before the receiving tank, these pollutants will be kept out of the subsequent

wastewater treatment system.

Characterisation of kennel wash-down wastewater is difficult, but we expect the levels of all

pollutants to be significantly lower than those contained in domestic wastewater.

3.3 Wastewater Quantity

The following sections outline the expected wastewater volumes generated in different parts of

the facility. This information will be used in selecting and designing an appropriate wastewater

treatment and land application system for the Site.

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3.3.1 Domestic Wastewater

Domestic wastewater will be generated by the dwelling/studio, staff and to a lesser extent,

visitors who use the toilet, sinks and kitchens. The volume of wastewater will depend on the

number of staff and visitors using the facilities as well as the number of residents in the

dwelling/studio. A small volume of kitchen wastewater will also be generated during food

preparation.

i. Residence – The Site contains an existing three (3) bedroom dwelling and studio (4-

bedrooms total). The occupancy rate applied is 1.6 persons per bedrooms as per

Section 6.2 of the draft MCC DAF (2018). The design wastewater flow allowance

used is based on Table 32 of the draft MCC DAF (2018), with 120L/person/day (tank

water supply) applied. Based on this, the estimated (design) daily wastewater load

from the residence is 768L.

ii. Staff – The Client advised that three (3) staff members are anticipated to operate the

facility, with two (2) living in the existing dwelling. Therefore, a maximum of one (1)

additional staff will be accounted for. The design wastewater flow allowance used is

based on AS/NZS 1547:2012 (Table H4), with 30L/person/day (non-resident staff)

applied. Based on this, the estimated (design) daily wastewater load from staff is

30L.

iii. Visitors – The visitors of the kennel will include Clients either picking up or dropping

off animals for care. Visitors typically use substantially less water per person than

staff members because of their shorter stay duration. Most visitors will generate no

wastewater at all, but some will make use of the bathroom facilities. We estimate a

(maximum) flow allowance of 6L/visitor/day. It is estimated the facility will have a

maximum of 10 visitors per day during peak times. Based on this, the estimated

(design) daily wastewater load from visitors is 60L.

iv. Food Preparation – The kennel will include an area for on-site food preparation for

the animals. Whilst it is likely that the majority of the food is dry (kibble etc.), there is

some preparation of cooked food (including rice and chicken). It is assumed that

animals will be fed twice per day and that preparation of meals will generate a

(maximum) of 0.5L of wastewater per meal. Based on this, the estimated (design)

daily wastewater load from kennel food preparation is 30L.

3.3.2 Greywater

Greywater is produced from dog washing and laundry operations within the facility. The volume

of greywater produced will depend on the frequency of both dog grooming and laundering

operations.

i. Grooming Services – Animal grooming is to be provided at the dog kennel facility.

The Client indicated that during peak times, up to eight (8) dogs could be washed

per day. We estimated a (maximum) flow allowance of 40L per wash for each

animal. Based on this, the estimated (design) daily greywater load from grooming

services is 320L.

ii. Laundry – The laundering of towels and other washable items used for animal care

will be done on-site. A conservative assumption of 70L per wash has been used

based on use of a 4-star (WELS) washing machine. Whilst the volume of washable

material requiring laundering will vary, one (1) load per day is anticipated during

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peak times. Based on this, the estimated (design) daily greywater load from laundry

services is 70L.

3.3.3 Kennel Operations

The proposed animal boarding facility will house up to 30 dogs (20 kennels total) with

associated indoor and outdoor open play areas.

i. Kennel Wash-down – The ‘typical’ wash-down procedure for kennels will involve

the dry removal of all solid material (faeces etc.) from each enclosure and animal

bedding using a brush and pan. Solid materials collected are then disposed of

appropriately off-site. The internal and external hard surface areas of each enclosure

are then mopped and washed. After the initial rinse, cleaners or sanitisers are spray

applied, before a final rinse. It is estimated that approximately 20L of water1 will be

used per kennel for wash-down. Based on this, the estimated (design) daily load

generated during cleaning procedures at the facility is 400L.

ii. Communal Play Area Wash-down – The same ‘typical’ wash-down procedures

used for kennel wash-down are applied for the cleaning of the communal play area.

The area will be cleaned daily. It is estimated that approximately 100L of water (~12

minute wash time1) will be used for the communal area wash-down. Based on this,

the estimated (design) daily load generated during cleaning procedures at the facility

is 100L.

3.3.4 Combined Wastewater Generation

The following table presents a summary of the estimated (combined) maximum daily

wastewater volumes for the proposed development, based on the information above. It

assumes average daily and peak hourly flows for residents, staff, visitors and facility operations

under maximum occupancy conditions.

Based on the above, a design wastewater load of 1,778L/day (rounded to 1,800L/day) has

been adopted as the basis for treatment design and land application system sizing.

1 1 The Husqvarna (PW125) pressure washer uses ~8L/minute (maximum). Consistent with other models.

Wastewater Flow

Allowance

(L/unit/day)

Unit Number

Design

Wastewater

Load (L/day)

Flow

Peaking

Factor (%)

Maximum

Expected

Wastewater Flow

(L/hr)

Dwelling plus Studio 1 120 bedroom 4 768 300 128

Staff (daytime only) 2 30 staff 1 30 5

Visitors + Clients (grooming services) 6 visitor 10 60 10

Food (kennel) Preparation 0.5 per meal 60 30 5

Dog Washing (grooming services) 40 per wash 8 320 53

Laundry Facilities 70 per wash 1 70 12

Kennel Wash-down 20 per kennel 20 400 67

Communal Play Area Wash-down 100 per wash 1 100 17

Expected Domestic Wastewater/Greywater Load (L/day) 1,278 213

Expected Wash-down Wastewater Load (L/day) 500 83

Total Design Wastewater Load (L/day) 1,778 296

Notes

1. Draft MCC DAF (2018) - Table 32 for tank water supply

2. AS/NZS 1547:2012 - Table H4 for non-resident staff

Design (average) Daily Wastewater Loads (L)

Source

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3.4 Water Conservation and Improving Wastewater Quality

It is strongly recommended that water efficient devices be installed wherever possible, to reduce

the demand on the potable water supply and hence the wastewater load for disposal. Some

possible water conserving devices include:

dual flush 6/3 litre toilets;

aerator faucets and flow restricting shower roses;

spring-loaded taps for basins;

water efficient dishwashers; and

water efficient front loading washing machines.

As well as reducing water use, it is important that the wastewater stream is protected against

harmful substances which could disrupt treatment processes. The following are a list of general

suggestions which could be implemented:

Sodium adds to the total salinity of wastewater and can have detrimental impacts on soils

when wastewater is disposed to the land. Sodium salts are present as fillers in many

powder detergents. To reduce sodium levels in wastewater, liquid detergents are

preferred;

Phosphorus is an essential plant nutrient that can be applied to the land with no

detrimental impacts, provided it is appropriately managed. However, it may cause

pollution problems when it runs off and enters waterways. The phosphorus concentration

in wastewater can be reduced by selecting detergents low in phosphorus;

Organic matter, oils and fats can enter the waste stream from various sources. Excessive

amounts of fats, oils and greases should not be disposed of into the wastewater stream;

and

Avoid placing oil, paint, petrol, strong acids or alkalis, degreasers, photography chemicals,

cosmetics, lotions, pesticides, herbicides and antibiotics in the wastewater system. Even

small amounts of these products can harm the performance of wastewater treatment

systems. Such materials should not be disposed of down the drain and alternative

disposal practices must be used.

4 Existing OSSM

There are currently two (2) existing OSSM systems on the Site, both with current Approval’s to

Operate. One (1) system services the dwelling and the other services the studio.

OSSM 1 – Dwelling

Generated wastewater from the dwelling currently undergoes primary treatment in a concrete

septic tank (approximately 2,000L), located immediately southwest of the dwelling. Primary

effluent from the septic tank is displaced to an absorption bed 3m wide and 12m long, providing

a basal area of 36m². The bed is located south of the tank.

No sign of damage or saturation was observed in the LAA during the Site investigation. The

tank was found to be in reasonable working order, with minimal sludge and good scum layer

formation. The concrete appeared to be in good condition, with no obvious structural damage.

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OSSM 2 – Studio

Generated wastewater from the studio currently undergoes primary treatment in a concrete

septic tank, located south of the studio. The tank was of small form and contained no inlet or

outlet inspection ports.

It is assumed that primary effluent is displaced to a downslope absorption field; however, no

evidence for the location was able to be identified.

Based on current standards, both existing treatment systems are undersized. Therefore, it is

recommended that both existing OSSM systems (septic tanks and absorption systems) be

decommissioned (see Section 4.1 below).

If suitable, and subject to plumber confirmation, the existing septic tank on the dwelling could be

repurposed for pre-treatment of the proposed kennels wastewater (see Section 5.1).

4.1 Decommissioning

4.1.1 Septic Tank

To prevent the redundant septic tank from causing public health, safety or environmental

problems, it should be decommissioned and removed in accordance with NSW Health Advisory

Note 3.

http://www.health.nsw.gov.au/environment/domesticwastewater/Documents/adnote3.pdf

As a guide, the procedure for the removal of in-ground treatment tanks is generally as follows:

1. Effluent and sludge should be removed from the redundant septic tank by an approved

contractor, utilising approved tanker vehicles and approved dump sites;

2. The sides, lid, baffle or partition (if fitted) and square junctions of the tank should be

hosed down as the waste is being removed;

3. The inlets and outlets should be plugged and the tank should then be filled with clean

water and disinfected to a minimum level of 5mg/L of free residual chlorine, with a

minimum one half hour contact time. The lid should be exposed to the chlorine solution.

The chlorine should be allowed to dissipate naturally at least overnight and not be

neutralised; and

4. The tank should be emptied (see point 1) before being safely removed.

4.1.2 Absorption System

Decommissioning of subsoil absorption systems used for human waste is subject to regulation

under the NSW EPA (2000) Environmental Guidelines: Use and Disposal of Biosolids.

Absorption systems accumulate biosolids with high concentrations of pathogens, nutrients and

BOD5 over the course of their operation. Contaminated solids (sludge and soil) require

treatment, depending on the intended disposal (or reuse) method.

To achieve a biosolids quality that is suitable for unrestricted use, the minimum treatment

requirements for 'Stabilisation Grade A' must be met, in accordance with Table 3-3 in the

‘Biosolids’ Guidelines (2000).

If in-situ stabilisation and burial is proposed, the system should be excavated and exposed.

Lime (e.g. quicklime) can then be incorporated into the systems fill material at a rate of

~25kg/m3; ensuring that the lime is mixed well throughout. The mixture should be covered and

left for 3 days (minimum), before being blended with clean backfill material and compacted to

the required density.

http://www.health.nsw.gov.au/environment/domesticwastewater/Documents/adnote3.pdf

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5 Proposed Wastewater Treatment

Given the identified Site and soil constraints and limited suitable EMA (areas with <20% slope),

primary treatment systems (i.e. septic tanks) are not recommended as they significantly limit

effluent disposal and reuse options and pose a higher risk to human and environmental health

compared to secondary or advanced treatment systems.

It is recommended that all wastewater streams (dwelling, studio, boarding facility) be combined

and treated in a new secondary treatment system. As the design wastewater load is

≤1,800L/day, a domestic treatment system is considered suitable for the Site.

5.1 Pre-treatment

Surface drains collecting kennel and communal play area wash-down water should be capped

with grates to provide preliminary solids removal. After the wastewater passes through the

grates, it will be directed through a coarse solids trap to capture residual coarse materials such

as animal hair and grit. The traps will need to be cleaned on an ‘as needs’ basis to ensure they

continue to work appropriately and do not become clogged.

Following grit removal, kennel wash-down water will drain directly into a primary treatment

system to provide additional preliminary treatment and removal of solids. The existing ~2,000L

dwelling septic tank could potentially be reused for this purpose if relocation is practical.

5.2 Wastewater Treatment System Options

A minimum effluent quality standard of secondary treatment with disinfection is recommended

for the proposed development. Secondary treatment is aimed at the removal of dissolved and

suspended organic material by a combination of physical and biological methods, usually

incorporating both aerobic and anaerobic phases. Secondary treatment presents a significantly

lower risk to human health and the environment, when compared to conventional primary

(septic tank) systems.

The NSW Ministry of Health (NSW Health) provides accreditation for domestic secondary

treatment systems in NSW. The system selected for use at the Site must hold such an

accreditation. Appropriate secondary treatment technologies include (but are not limited to) the

following:

Aerated Wastewater Treatment Systems (AWTS);

Media / textile filter systems;

Aerobic sand filters (accredited or site-specific design required); and

Reed beds (accredited or site-specific design required).

Section 6.4.1 of the draft MCC DAF (2018) describes the minimum effluent quality standards for

secondary treatment systems. The nominated treatment system supplier must warrant the

selected system by providing a ‘Producer Statement’ that illustrates the system layout and

configuration, describes and quantifies the hydraulic design, as well as provides confirmation

that the desired effluent standards can be met.

A detailed list of suitable NSW Health accredited systems can be found at:

http://www.health.nsw.gov.au/environment/domesticwastewater/Pages/default.aspx

Disinfection units are typically installed as a standard component of proprietary secondary

treatment systems, or can be installed as an add-on by the system supplier. We recommend

http://www.health.nsw.gov.au/environment/domesticwastewater/Pages/default.aspx

14

that a disinfection system is installed with the chosen system. Domestic systems typically use

one or a combination of the following disinfection methods:

Ultra Violet (UV) irradiation; and/or

Chlorination.

Final system selection is the responsibility of the Owner; however, selection and installation of

the system must follow the requirements of Section 6.4 of the draft MCC DAF (2018).

5.2.1 Treated Effluent Quality

The expected effluent quality of all NSW Health accredited OSSM systems are provided in their

associated accreditation certificates.

Secondary treatment systems are expected to achieve the minimum water quality standards for

‘secondary’ effluent, as detailed in Table 33 of the draft MCC DAF (2018) and reproduced here.

Parameter Loading

Biochemical Oxygen Demand 20mg/L

Suspended Solids 30mg/L

Faecal Coliforms 30cfu/100mL

Total Nitrogen 30mg/L

Total Phosphorus 10mg/L

The listed phosphorus and nitrogen concentration values are targets (only) and have been

adopted for nutrient modelling in this WMR.

5.2.2 System Siting

The exact positioning of the treatment system will depend on the local gradient and level

controls and can be determined in consultation with a licensed plumber and Council prior to

obtaining consent for the installation of the system. A nominal treatment system location is

provided on the Site Plan (Figure 3) in Appendix A.

5.2.3 System Operation and Management

Successful performance of wastewater treatment systems relies on periodic monitoring and

maintenance, which will be the responsibility of the Owner. The selected treatment system must

be serviced by a suitably qualified technician at the prescribed intervals.

6 Proposed Effluent Management

This section describes the Sites capability for effluent management and provides design details,

including sizing of the required LAA. As detailed above, secondary treatment is considered the

most appropriate wastewater treatment option for the proposed development.

6.1 Buffers

Buffer distances from LAAs are recommended to minimise risk to public health, maintain public

amenity and protect sensitive environments. Buffer or setback distances are recommended to

provide a form of mitigation against unidentified hazards and reduce potential pathways of

human and environmental exposure.

15

The following environmental buffers are required, based on Table 39 of the draft MCC DAF

(2018):

250m from domestic groundwater bores;

100m from permanent watercourses;

40m from intermittent watercourses and dams;

6m if area up-gradient and 3m if area down-gradient of driveways, swimming pools and

buildings;

12m if area up-gradient and 6m if area down-gradient of property boundaries; and

0.6m vertical separation from hardpan or bedrock.

All of the recommended buffer distances are achievable on-site, as shown on the Site Plan

(Figure 3, Appendix A).

6.2 Onsite Effluent Management Options

W&A have considered the suitability of various land application systems in relation to the

identified Site and soil limitations. In determining the suitability of the various options we have

assessed the Site constraints and the relative environmental and public health risks associated

with each.

The table below provides a summary analysis of the range of effluent land application options

considered, and presents recommendation for the preferred approach to be used in conjunction

with the secondary treatment system selected.

Land Application Option Suitable Reasoning

Absorption Trenches/Beds

Yes Site soils are considered suitable with secondary effluent quality, appropriately conservative DLR and minimal in-soil storage allowance.

ETA Beds Possible Same as above. However, they have been discounted due to less favourable climate conditions and the larger bed lengths required.

Mounds Possible

While suitable, Site conditions do not indicate the necessity for mounds to overcome an identified soil constraint. Mounds are further discounted due to their substantial cost.

Surface Irrigation No Surface spray irrigation not permitted for new or upgraded OSSM systems (draft MCC DAF, 2018).

Subsurface Irrigation Possible While suitable, subsurface irrigation is not considered practical given the terrain and limited suitable EMA.

Monthly water and (annual) nutrient mass balance has been used to prepare preliminary sizing

for two (2) suitable LAA options. The results of the analysis are presented in the following table.

Both options include ‘zero’ storage allowance to ensure sufficient conservatism is incorporated

into the design.

16

PRELIMINARY DESIGN CALCULATIONS

Land Application Option Required LAA (m²)

Absorption Bed 230

Subsurface Irrigation 2,200

Based on the analysis and limited suitable EMA, a subsoil absorption bed is the preferred

effluent land application option for the proposed development. A description of the preferred

effluent management method and (nominal) sizing are presented below.

6.3 Conventional Bed Design

A conventional bed allows for safe and reliable application of generated effluent within the

identified LAA at loading rates appropriate for Site (subsoil) conditions. During wetter periods of

the average climate year, treated effluent can be safely stored in the bed for later infiltration.

A ‘typical’ conventional bed installation comprises 300-600mm of (20-40mm) distribution

aggregate below 100-150mm of topsoil. W&A recommend a design consisting of a 300mm

(aggregate / self-supporting arch) distribution bed covered by 100mm of topsoil.

Typical design and installation details for absorption beds are provided in AS/NZS 1547:2012

(Appendix L). Figure 5, Appendix A of this report also provides a standard design figure and

construction notes for the proposed absorption bed system.

The land application system should be installed by a suitably qualified professional, ensuring

that effluent is distributed evenly across the entire area serviced.

6.3.1 Distribution

To optimise LAA performance, a dedicated distribution manifold should be installed within each

bed. Distribution may be achieved by drilled PVC pipe (per LPED) or alternately using pressure-

compensating subsurface irrigation (SSI) line. Both options would be sleeved with 100mm

slotted PVC pipe and with manual flush valves (in valve box) fitted to the terminal end of the

distribution manifold on each bed. To reliably proportion effluent evenly between the beds, a

hydraulic indexing valve (or similar) will be required.

It will be important to ensure that the irrigation pump installed in the treatment system is capable

of managing ‘duty’ requirements for the LAA distribution system (installer to confirm).

6.4 LAA Sizing and OSIA

As part of the wastewater is classified as ‘non-human’, it is necessary to demonstrate that the

development can meet site-specific environmental and health protection (E&HP) targets by

preparing an Off-site Impact Assessment (OSIA), in accordance with Section 1.6 of the draft

MCC DAF (2018).

The draft MCC DAF Technical Manual (2019) outlines the minimum requirements for OSIA for

unsewered development of ‘High hazard’ non-domestic allotments. Section 3.2 of the draft MCC

DAF (2018) requires daily water, nutrient and pathogen modelling to size any LAA and Section

9.1.2 of the draft MCC DAF Technical Manual (2019) requires preparation of an OSIA to

demonstrate that the environmental and public health risks are adequately managed.

OSIA is an indicative risk assessment tool that involves the use of continuous daily soil/water

modelling to maximise potential to achieve a sustainable design and provide a high level of

assurance when assessing potential impacts on receiving environments. The adopted

17

methodology involves establishing background pollutant loads and contaminant concentrations,

calculation of catchment surface and subsurface discharge characteristics, and integration of

site-specific OSSM inputs using the Land Application Mass balance (LAM) model to estimate

the potential for human health and environmental impacts from OSSM systems.

The minimum required size of the LAA is determined through iterations of the daily model, with

the results compared to the established E&HP targets.

Table 17 in the draft MCC DAF Technical Manual (2019) describes the minimum assessment

requirements for an OSIA and are reproduced in the table below.

Risk Assessment Component Minimum Standard

On-lot Land Application Area (LAA) Assessment

Daily water and nutrient mass balance modelling for each general on-site system / LAA type within the subject site used to derive average annual hydraulic and pollutant loads to surface and subsurface export routes. Also used to estimate frequency of hydraulic failure (surcharge).

Rainfall-Runoff

Average annual estimate of runoff volume using a volumetric coefficient of rainfall.

Recommend use of Figure 2.3 (and subsequent equations) from Fletcher et al. (2004).

Surface and Subsurface Pollutant Export

Site specific calculation of catchment attenuation factors for both surface and subsurface on-site loads based on data obtained through desktop and field site and soil investigations and representative of the characteristics of the receiving environment. To include viral die-off modelling to ensure human health targets.

Mass balance combining attenuated on-site system flows and loads with catchment inputs.

Background Pollutant Loads / Concentrations

Sourced from Tables 2.44 - 2.45 or Figures 2.15 – 2.23 of Fletcher et al. (2004).

Acceptable export rates / concentrations sourced from published local studies.

Environment and Health Protection Targets

No more than 10% increase in average annual nitrogen and phosphorus loads (kg/year) based on existing undeveloped background loads.

Average virus concentration <1 MPN/100ml at receiving water or exposure point after application of attenuation rates.

All land application areas sized to ensure hydraulic failure (surcharge) accounts for only 5% of total wastewater generated (i.e. 95% containment via evapotranspiration and deep drainage).

6.4.1 Existing (Baseline) Condition

The effective impervious area of the Site was set to 5% for the existing condition (see Figure 2,

Appendix A). To estimate the average annual background pollutant load for the Site, the

average annual rainfall runoff coefficient was first obtained using the calculation provided in

Section 2.2 of Fletcher et al. (2004):

C = (0.83 - 0.00018R) x Imp + 0.0013R0.8 – 0.095

Where C = Annual Runoff Fraction

R = Mean Annual Rainfall

18

Imp = Impervious Fraction.

Average annual rainfall for the Site is 1,225mm (see Table 14 in Technical Manual) which

equates to an annual runoff fraction of 0.32. The average annual runoff volume is then

calculated using the Rational Method:

Q = C x I x A

Where Q = Annual Runoff Volume (ML/year)

I = Average Annual Rainfall (mm/year)

A = Site Area.

Given that the Site area is approximately 18,270m2, the expected runoff volume equates to

7.16ML/year.

6.4.2 Pollutant Generation and Export

Background nutrient (N and P) export concentrations were derived using ‘recommended typical’

values from Tables 2.44 and 2.45 of Fletcher et al. (2004) for ‘mixed urban/rural’ land use.

Section 10.2.1.4 of the draft MCC DAF Technical Manual (2019) recommends applying dry

weather concentrations for 20% of the runoff volume and wet weather concentrations to the

remaining 80%. A summary of the background nutrient export loads and average

concentrations are provided in the table below.

Parameter Average Loads (kg/year) Average Concentration (mg/L)

Total Phosphorus (TP) 1.65 0.23

Total Nitrogen (TN) 13.03 1.82

6.4.3 Daily Soil Water and Nutrient Modelling

The LAM is a Microsoft Excel based daily water, nutrient and pathogen mass balance model

developed by BMT WBM for predicting the performance of OSSM systems under varying

environmental conditions. The algorithms in the model have been derived from the

Decentralised Sewer Model (DSM) and tailored to suit a single site application. It can assess

long-term environmental and human health performance of wastewater systems.

The LAM requires a range of bio-physical parameters as inputs to determine whether a LAA

option would be sustainable at the Site. The model can predict OSSM performance by

simulating the movement of pollutants (nutrients and pathogens) within the effluent load as it

travels from the point source (onsite or community-scale systems) as surface or subsurface

flows. The LAM does not predict the minimum area required to achieve zero surface runoff or

deep drainage, instead, like the nominated area approach of the monthly water balance, the

model predicts the surface and subsurface discharges based on a set of nominated conditions

such as receptor sensitivity, soil, slope, climate, wastewater input and available area.

A summary of the model processes, inputs and results is provided below.

6.4.3.1 Model Inputs

The simulation was run for a data period of 60 years (1959-2019) and represents a conservative

estimate of long-term performance based on available information and a set of assumptions as

detailed within this WMR. Simulations were carried out for the preferred land application option

(absorption bed) to determine the minimum LAA requirements.

19

Rather than simplistic loading rates, as utilised in monthly modelling, the LAM inputs include a

more detailed estimation of the soils ability to receive, store and transmit water by

approximating parameters such as effective saturation, field capacity, and the infiltration

exponent.

Soil chemistry input data was based on analytical results for soil samples taken from TP2. The

input data sheets used in the modelling are presented in Appendix C.

Daily climate data used in the model was sourced from 'SILO Data Drill' information available

through the QLD Department of Environment and Science. The adopted SILO data set uses the

(FAO56) Penman-Monteith methodology to estimate reference evapotranspiration (ET0), which

is a function of both evaporation and transpiration factors, based on a specific reference crop

planted in the LAA (assumes turf).

6.4.3.2 Pollutant Attenuation Factors

Natural attenuation of excess effluent nutrient loads from a LAA will occur within the underlying

soil and groundwater, providing reductions in contaminant concentrations to mitigate off-site

export.

Established pollutant attenuation rates for hydraulics, pathogens, nitrogen and phosphorus are

adopted from Table 24 in the draft MCC DAF Technical Manual (2019). These attenuation rates

have been established through modelling undertaken in several case studies for both inland /

rolling hills and coastal / estuarine catchment scenarios and depending on whether MCC

prescribed setbacks are achievable.

Based on the location and soil characteristics of the property, the inland / rolling hills catchment

scenario has been adopted, with attenuation rates of 60% for hydraulics, 99% for nitrogen, 98%

for phosphorus and 99% for pathogens considered appropriate.

6.4.4 LAM Results and Compliance

Hydraulic and nutrient generation is divided into surplus loads discharged to the ground surface

as ‘surface surcharge’ or draining below the root zone with subsequent (eventual) groundwater

migration to surface water bodies or aquifers as ‘deep drainage’. The following sections outline

the results of the modelling and their compliance with the required acceptance criteria.

The model was run iteratively to establish the minimum required LAA for an absorption bed. The

results from modelling demonstrate compliance with the minimum standards of the draft MCC

DAF (2018). Copies of the model run input and output results are presented in Appendix C.

6.4.4.1 Hydraulic Loads

Modelling of the movement of water, from both applied effluent and rainfall, through the soil is a

key component of the LAM, ultimately determining the nutrient movement throughout the LAA.

The table below presents the mean annual overflow, surface surcharge and deep drainage

predicted for the 60-year modelling period.

Parameter Run 001

Run Description Secondary to absorption bed

Total LAA (m²) 180

Surface Surcharge Frequency (days/year) 6.7

Surface Surcharge as (%) total WWF 0.9

20

Deep Drainage (mm/day) 9.49

The results from model Run 001 show that surface surcharge is expected to account for 0.9% of

the total wastewater volume generated. Additionally, following application of the specified

hydraulic attenuation factor (60%), the daily deep drainage is expected to be <3.8mm/day.

6.4.4.2 Nutrient and Pathogen Results

The table below summarises the predicted mean annual nutrient and pathogen loads generated

by the proposed LAA design and released beyond the LAA footprint.

Parameter TP (kg/year) TN (kg/year) TVirus (MPN/L)

Deep Drainage Output 5.6 1.24 N/A

Surface Surcharge Output 0.1 0.01 N/A

Combined OSSM System Output 5.7 1.25 1.0

LAM modelling shows that nutrient export through surface surcharge is minimal. Deep drainage

is the principal pathway for nutrient export beyond the LAA footprint.

6.4.4.3 Catchment Pollutant Attenuation

Pollutant (nutrient and pathogen) loads generated at the LAA will continue to undergo

assimilation (capture, conversion, destruction etc.) within the soil environment as treated

effluent moves away from the LAA.

The extent to which this occurs is based generally on the area available for assimilation (applied

buffers) and the nature of the soil environment (landform/morphology). The attenuation factors

specified in Section 6.4.3.2 have been applied for nitrogen, phosphorus and pathogen loads

from the proposed LAA. The resulting pollutant export concentrations are presented in the table

below.

Parameter TP (kg/yr) TN (kg/yr) TVirus (MPN/L)

Background Load 1.65 13.03 N/A

Combined OSSM System Output 5.7 1.25 1.0

Attenuation Factor (%) 98 99 99

Attenuated Export Load 0.114 0.013 0.01

Background Load + Attenuated Export Load 1.764 13.043 N/A

Increase from Background Export Load (%) 6.9 0.1 N/A

As shown, attenuated nutrient export loads are expected to achieve the required E&HP target of

<10% increase over (background) average annual nitrogen and phosphorus loads (kg/year).

The pathogen export target of <1MPN/100ml (<10MPN/L) is also readily achievable.

Taking into consideration the proposed LAA location and application method, sensitive

receptors are not expected to be impacted, with pathogen assimilation occurring well within the

available setbacks.

21

6.4.5 OSIA Results

This OSIA addresses the various environmental and public health risks associated with the

proposed OSSM system for the Site. The combination of a secondary treatment system with

subsurface land application within a 180m2 (absorption bed) area demonstrates that the

potential for contaminant migration away from the LAA is low and there is a reasonable

expectation that, should very low levels of contaminants leave the immediate area of land

application, they will be reduced to below background levels before reaching any sensitive

receptors.

Modelling shows that predicted hydraulic loads are sustainable, with minimal surface surcharge

expected. Also, it is shown that nutrients will be retained within the LAA, with less than a 10%

increase in nutrient export concentrations, and pathogens will be effectively attenuated well

before they can reach groundwater.

Based on our analysis, the risk of nutrient, hydraulic and pathogen export to surface waters and

groundwater posed by the proposed system will not be significant. Furthermore, the human and

environmental health risk to neighbouring properties is considered negligible.

6.5 LAA Design and Positioning

Available and suitable areas for effluent application are shown on the Site Plan (Figure 3,

Appendix A) as ‘Available EMA’. These areas exclude minimum setback distances as described

in Section 6.1.

The LAA is recommended to be installed as three (3) separate absorption beds with the

following dimensions; 20m (length) across the slope, 3m (width) and 0.4m (depth). The

preferred location for construction of the absorptions beds is shown on Figure 3, Appendix A.

The final plumbing design will be the responsibility of a certified plumber and must adhere to the

relevant codes and standards.

7 Mitigation Measures

7.1 Soil Improvement

7.1.1 Soil Depth

Prior to absorption bed installation the proposed LAA must first be formalised by removing any

foreign objects / waste material to create a natural ground surface. The base of the proposed

LAA should be deep ripped to ~300mm with large rock floaters removed.

If the required depth is not available, it is recommended to import good quality (sandy clay

loam) topsoil to the LAA to ensure a minimum separation of 600mm between the base of the

beds and any subsurface limitation.

The achievable separation must be confirmed by the irrigation installer, as rock depths vary

throughout the Site. Locally won (e.g. building envelope) or imported clean topsoil material

should be used and blended in with the existing LAA topsoil.

7.1.2 Soil Chemistry

Given that Site soils have very low fertility and are marginally sodic, they may be highly

susceptible to erosion, structural decline, surface crusting and can have very low infiltration

capacities, low hydraulic conductivity and high shrink/swell properties on wetting and drying.

Additionally, soil analysis identified moderate to very strong acidity which may impact vegetative

22

growth in the LAA. These properties can combine to reduce the soils’ capacity to sustainably

manage wastewater.

Prolonged application of sodium rich wastewater can exacerbate the situation. Application of

calcium mineral is a recognised way of reducing the effects of soil instability. It does this by

supplying calcium to the affected soil and thereby elevating calcium concentrations with respect

to sodium. Typically, gypsum would be the preferred soil amendment; however, given the

identified acidity concern a 50:50 application of gypsum and lime may be more suitable for the

Site. Both gypsum and lime are only slowly soluble in water, so simply broadcasting at the

surface can be of limited benefit as it can take a long time for the calcium to penetrate the soil

and reach the deeper soil layers. Therefore, it is necessary to incorporate the amendment into

the subsoil during construction of the land application system. A suitable gypsum/lime

application rate of approximately 0.5kg/m2 should be applied.

7.2 Vegetation Establishment

Vegetation that is suited to the application of effluent, preferably with high water and nutrient

requirements (such as turf) should be established over the LAA following construction. A

complete vegetation cover is important to reduce the erosion hazard and optimise water and

nutrient uptake. It is recommended to establish and maintain a vegetated buffer around the

LAA. It should be planted with moisture-tolerant vegetation and remain well maintained to

maximise moisture uptake. Plants must be selected that will not be so large as to shade the

LAA once fully grown. It is important that the LAA receives maximum exposure to sun and wind

to maximise evapotranspiration.

To maximise assimilation of effluent-borne nutrients within the LAA, vegetation clippings should

be removed from the LAA and mulched elsewhere on-site for use in other landscaped areas

that are not used for wastewater application. Mulching the clippings back onto the area from

which they were cut is not recommended. An alternative is to dispose clippings in the general

waste bin, or green waste bin collection service, if provided.

7.3 Stormwater Management

The performance of LAAs (and potentially treatment systems) can be adversely affected if

stormwater is allowed to run onto these areas. Stormwater diversion devices should be

designed and constructed to collect, divert and dissipate collected run-on away from the LAA.

The structure(s) should be designed and installed by a suitably qualified professional and be

compliant with relevant guidelines and standards.

A diagram of a ‘typical’ stormwater diversion, which would be appropriate for this purpose, is

provided in Appendix A, Figure 4. The outlet must be stabilised and must discharge water in a

safe location where it will not create an erosion hazard or impact on structures or neighbouring

properties.

23

8 Conclusions and Recommendations

This completes our assessment of the Sites capability for sustainable OSSM in relation to the

proposed animal boarding facility. Specifically, we recommend the following:

Repurpose the existing (~2,000L) dwelling septic tank (if practical) for pre-treatment of

kennel wastewater or, alternately a new tank will be installed;

Generated wastewater from the dwelling, studio and kennel will be treated to a

secondary standard (with disinfection);

The selected domestic secondary treatment system must be NSW Health accredited

and should be installed by an experienced professional, taking into account the

expected flows and other recommendations contained within this report;

Treated effluent will be reused on-site via three (3) absorption beds (20m long, 3m wide

and 0.4m deep), provided the selected application method is appropriately located,

installed and operated;

The LAA must be located within the available EMA specified to comply with adopted

setbacks from surface waters, property boundaries and other improvements (draft MCC

DAF, 2018 and NSW DLG, 1998);

An indexing valve (or similar) will be installed to evenly distribute effluent between the

three (3) beds;

Surface grates (to capture coarse solids) should be installed within the proposed kennel

area;

Installation of a coarse solids trap;

A suitable lime/gypsum application rate of approximately 0.5kg/m2 should be applied at

the base of the land application system prior to installation;

Vegetation must be established over the LAA immediately after installation;

Stormwater run-on must be directed away from the proposed LAA; and

Vehicles and grazing animals must be prevented from entering the designated LAA.

Yours Sincerely,

Elise Powning

Environmental Consultant

Whitehead & Associates

24

Appendix A

Figures

30

Appendix B

Soil Borelogs and Laboratory Data

31

Depth

(m)

Gra

phic

Log

Sam

plin

g

depth

/nam

e

Horizon

Texture Structure Colour MottlesCoarse

Fragments

Moisture

ConditionComments

TP1/1 A1 SCL Weak 10YR 3/1 very Nil <5% D

0.1 dark grey

TP1/2 A2 SCL Apedal to 10YR 4/1 dark Nil 5-10% D

0.2 weak grey

TP1/3 B SC Apedal to 10YR 5/2 Nil 10-15% D

0.3 Weak grey ish brown

0.4 Refusal on rock @ 0.35m

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

PROFILE DESCRIPTION

Notes: - refer to site plan for position of test pit

Site: 96 Coomba Road, Charlotte Bay NSW Excavated/logged by: Elise Powning

Date: 12 September 2019 Excavation type: Auger & rockbar

Soil Bore Log

Client: Trent Parmenter Test Pit No: TP1

Whitehead & AssociatesEnvironmental Consultants Pty Ltd

32

Depth

(m)

Gra

phic

Log

Sam

plin

g

depth

/nam

e

Horizon


Fragments

Moisture

ConditionComments

TP2/1 A SCL Weak to 10YR 4/2 dark Slight orange <5% D

0.1 moderate grey ish brown

0.2 TP2/2 B1 SCL-SC Moderate 2.5Y 5/2 Slight orange <5% D

greyish brown

0.3

0.4

0.5 TP2/3 B2 SC Moderate 2.5Y 6/2 light Slight orange 5% SM

brownish grey

0.6

0.7

0.8

Refusal on rock @ 0.8m

0.9

1.0

1.1

1.2

1.3

1.4

1.5

PROFILE DESCRIPTION




Soil Bore Log



33

Depth

(m)

Gra

phic

Log

Sam

plin

g

depth

/nam

e

Horizon


Fragments

Moisture

ConditionComments

TP3/1 A SCL Weak to 2.5Y 4/3 olive Slight orange 5-10% SM

0.1 moderate brown

0.2

0.3

TP3/2 B1 SC Moderate 7.5YR 5/4 brown Orange and 5-10% D-SM

0.4 red

0.5

0.6 TP3/3 B2 SC Moderate 10YR 5/6 Orange and 5-10% SM

yellowish brown red

0.7

0.8 Refusal on rock @ 0.75m

0.9

1.0

1.1

1.2

1.3

1.4

1.5

Soil Bore Log




PROFILE DESCRIPTION



34

SiteSample

Name

Sample

Depth (mm)

Texture

Class

EAT [1]

Rating

[2]

pH f [3]

pH 1:5

[4]

RatingEC 1:5

(µS/cm)

ECe

(dS/m)

[5]

RatingOther analysis

[6]

1/1 100 CL 8 Low n/a 5.2 Strongly acid 12 0.11 Non-saline

1/2 200 CL 3(1) Low n/a 4.7 Very strongly acid 44 0.40 Non-saline

1/3 350 LC 3(1) Low n/a 5.0 Very strongly acid 31 0.25 Non-saline

2/1 150 CL 3(2) Low n/a 5.1 Strongly acid 29 0.26 Non-saline CEC, Psorb

2/2 450 LC 3(3) Mod n/a 5.5 Moderately acid 8 0.06 Non-saline CEC, Psorb

2/3 800 LC 3(3) Mod n/a 5.2 Strongly acid 14 0.11 Non-saline CEC, Psorb

3/1 300 CL 3(2) Low n/a 5.3 Strongly acid 15 0.14 Non-saline

3/2 550 LC 3(3) Mod n/a 5.4 Strongly acid 19 0.15 Non-saline

3/3 750 LC 3(3) Mod n/a 5.6 Moderately acid 23 0.18 Non-saline

[1]

[2]

[3]

[4]

[5]

[6]

Total nitrogen

Electrical conductivity of the saturated extract (Ece) = EC1:5(µS/cm) x MF / 1000. Units are dS/m. MF is a soil texture multiplication factor.

The modified Emerson Aggregate Test (EAT) provides an indication of soil susceptibility to dispersion.

Ratings describe the likely hazard associated with land application of treated wastewater.

CEC (Cation exchange capacity)

TP1

TP2

TP3

Psorb (Phosphorus sorption capacity)

Organic carbon

Bray Phosphorus

pH measured in the field using Raupac Indicator.

External laboratories used for the following analyses, if indicated:

96 Coomba Road, Charlotte Bay NSW - Soil Sampling Schedule and Results of pH, EC and EAT Analysis

pH measured on 1:5 soil:water suspensions using a Hanna Combo hand-held pH/EC/temp meter.

Notes:- (also refer Interpretation Sheet 1)

37

Appendix C

Modelling Inputs and Results (Run 001)

38

Summary of Results

Runoff (surcharge) frequency 6.7 days/year

Runoff (surcharge) volume 0.9 % of total WWF volume

Deep drainage volume 623.2 m3/yr

Total phosphorus load in runoff 0.1 kg/yr

Total nitrogen load in runoff 0.01 kg/yr

Total phosphorus load in deep drainage 5.6 kg/yr

PO4 concentration in deep drainage 9.4 g/cub.m

Total nitrogen load in deep drainage 1.24 kg/yr

NO3 concentration in deep drainage 2.0 g/cub.m

Total site virus load 638877 MPN/yr

Total site virus concentration 1.0 MPN/L

Total site phosphorus load 5.7 kg/yr

Total site nitrogen load 1.25 kg/yr

Storage overflow frequency 0 number of years

0.0 days/year

Storage overflow volume 0.0 cub.m/yr

0.0 % of total WWF volume

Land Application Management Tool (Run 001)

ViewTimeseries

Results

Site Data Soil Data

1 2 3 4

Application Area (m2) 180 Effective Saturation (mm) 420.0

Land Application Type 1 Field Capacity (mm) 380.0

Storage Type 1 Permanent Wilting Point (mm) 300.0

Application Method 1 Saturated Hydraulic Conductivity (mm/day) 120.0

Storage Capacity (m3) 0 Soil Depth for P Sorption (m) 0.8

Storage Depth (m) 0 Bulk Density (kg/m3) 1400.0

Average Slope (%) 8 Depression Storage (mm) 6.0

Soil Type A Infiltration Rate (mm/day) 200.0

Crop Type Default Infiltration Exponent 2.5

Coefficient P Sorption 140.1

Exponent P Sorption 0.33

Exponent P Desorption 0.16

Land Application and Acceptance Rates Crop Data Meteorological Data

Storage Seepage (mm/day) 0 January 0.8 Number of Years 60.1

Fixed Application Depth (mm) 10 February 0.8 R ET E T

Soil Water Trigger (mm) 0 March 0.7 Max 205.4 8.8 14.2 32.0

Additional Application Depth (mm) 0 April 0.6 Min 0.0 0.5 0.2 6.8

Nitrogen Crop Uptake (kg/ha/yr) 260 May 0.55 Average 3.8 3.2 3.9 18.3

Phosphorus Crop Uptake (kg/ha/yr) 30 June 0.5 Median 0.0 2.9 3.6 18.5

July 0.55 Standard Deviation 10.7 1.4 2.0 4.1

Constant Daily WWF (m3/day) 1.8 August 0.6

Total Nitrogen (mg/L) 30 No September 0.7

Total Phosphorus (mg/L) 10 October 0.8 ONLY grey cells require input.

Virus (MPN/L) 300 November 0.8 Refer to comments within cells for instructions

###### m3/day December 0.8

Layer # (Single Layer Version)

Land Application Management Tool (Run 001)

Use WWF

timeseries

instead?

Wastewater Characteristics

View Data

RunModel

Add New

Add New View Data

39

Appendix D

General Notes


Soil Physical Properties / Chemistry pH

This test is used to determine the acidity or alkalinity of native soils. pH is measured on a scale

of 0 to 14, with 7 being neutral. Results below 7 are considered acid, while those above 7 are

alkaline. For land application of effluent, soil with a pH of 4.5 to 8.5 should typically pose no

constraints. Soil pH affects the solubility and fixation of some nutrients; this in turn reduces soil

fertility and plant growth. By correcting soil pH beneficial plant growth is improved, assisting in

the assimilation of nutrient and improving evapotranspiration of effluent. Most Australian soils

are naturally acidic.

Electrical Conductivity

Electrical conductivity (EC) is a measure of a soil or soil/water extracts ability to conduct an

electrical current. It is used as an indirect measure of a soils accumulation of water soluble

salts, mainly of sodium, with minor potassium, calcium and magnesium. High EC within a land

application area reflects general soil salinity and is undesirable for vegetation growth. The

tolerance of vegetation species to soil salinity varies among plant types. Typically EC readings

of <4dS/m pose no constraints. There are a number of measures available to counter high soil

EC values for land application of effluent; however, the most important measure relates to the

conservative selection of application rates and appropriate application area sizing.

Emerson Aggregate Test

The Emerson Aggregate Test (EAT) is a measure of soil dispersibility and susceptibility to

erosion and structural degradation. It assesses the physical changes that occur in a single ped

of soil when immersed in water, specifically whether the soil slakes and falls apart or disperses

and clouds the water. Dispersive soils pose limitations to on-site sewage management because

of the potential loss of soil structure when effluent is applied. Soil pores can become smaller or

completely blocked, causing a decrease in soil permeability, which can lead to system failure.

Cation Exchange Capacity

The cation exchange capacity (CEC) is the capacity of the soil to hold and exchange cations

(positively charged molecules). Because some soils have a dominant negative charge, they can

adsorb cations. Soils bind cations such as calcium, magnesium, potassium and sodium,

preventing them from being leached from the soil profile and making them available as plant

nutrients. CEC is a major controlling agent for soil structural stability, nutrient availability for

plants and the soils’ reaction to fertilisers and other ameliorants. A CEC of greater than 15

cmol+/kg or me/100g is recommended for land application systems. Adding organic matter

(compost/humus) to soil can greatly increase its CEC.

Exchangeable Sodium Percentage

The exchangeable sodium percentage (ESP) is an important indicator of soil sodicity, which

affects soil structural stability and overall susceptibility to dispersion. Sodic soils tend to have a

low infiltration capability, low hydraulic conductivity, and a high susceptibility to erosion. When

sodium dominates the exchangeable cation complex, soil structural stability declines

significantly. Soil ESP is considered acceptable for effluent application areas when it is below

5%, marginal between 5% – 10% and limiting >10%. The ESP of application area soils can be

improved by the measured application of calcium (lime/gypsum).



41

Phosphorus Sorption Capacity

Phosphorus sorption (P-sorption) capacity is a direct measure of a soils ability to adsorb

phosphorus. Phosphorus is an important plant nutrient and is the limiting available nutrient in

many aquatic environments. Excess phosphorus can increase the production of nuisance

vegetative growth such as algae. The P-sorption capacity of the soil in an effluent application

area relates to its ability to assimilate the phosphorus in the wastewater for the design life of the

application area. P-sorption values greater than 400mg/kg is considered acceptable for land

application of effluent, while values below 150mg/kg present a constraint.

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