developments in sydney

8/3/2019 Developments in Sydney

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Sydney Catchment Authority

Developments in Sydneys DrinkingWater Catchment

Water Quality Information Requirements


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Disclaimer

This document includes information about undertaking or assessing a developmentin the drinking water catchment. The information is current, accurate and complete atthe time of publication.

The Sydney Catchment Authority does not make or give any representation orwarranty that using this information will prevent all water quality and other impactsand will not be liable in negligence, breach of contract or statutory duty for any failureor the consequences of that failure.

Copyright

State of New South Wales through the Sydney Catchment Authority, 2011. Youmay copy, distribute, display, download or otherwise freely deal with this work for anypurpose, provided that you attribute the Sydney Catchment Authority as the owner.However, you must obtain permission if you wish to (1) charge others for access tothe work (other than at cost), (2) include the work in advertising or a product for sale,

or (3) modify the work.


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Contents1. Introduction ........................................................................................................... 4

The Sydney Catchment Authority .................................................................. 4Neutral or beneficial effect on water quality ................................................... 4

Model development control plan clause ......................................................... 6

2. The water cycle management study ...................................................................... 63. General information requirements ......................................................................... 7

Certification.................................................................................................... 84. Erosion and sediment control measures ................................................................ 85. Stormwater requirements ...................................................................................... 9

MUSIC model and report ............................................................................... 9Site development details ...............................................................................10Proposed stormwater management ..............................................................10Proposed offset measures ............................................................................11Modelling results ...........................................................................................11

6. Wastewater reports ..............................................................................................11Wastewater loading ......................................................................................11Site constraints map .....................................................................................12Soil information .............................................................................................13Climatic information ......................................................................................13General evaluation........................................................................................13Effluent management area sizing ..................................................................14Site plan for location of effluent management area .......................................15Effluent irrigation ...........................................................................................15Special considerations ..................................................................................15

7. More information ..................................................................................................178. Glossary ...............................................................................................................189. Acronyms .............................................................................................................2110. References .........................................................................................................22


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1. Introduction

Development in Sydneys Drinking Water Catchment Water Quality InformationRequirements describes what you need to do for developments that need a watercycle management study. It describes the different reports and modelling you need toinclude with a development application, and how they vary for different types andscales of development.

The Sydney Catchment Authority

The Sydney Catchment Authority (SCA) is a NSW government agency created in1999 to manage and protect the drinking water catchment and supply raw water toSydney Water, a number of local councils and other customers. Sydneys drinkingwater catchment covers approximately 16,000 square kilometres and suppliesdrinking water to around four and a half million people in Sydney, the BlueMountains, the Illawarra, Shoalhaven and the Southern Highlands (Figure 1).

Neutral or beneficial effect on water quality

Development in the drinking water catchment is regulated by State EnvironmentalPlanning Policy (Sydney Drinking Water Catchment) 2011 (the SEPP - previously theDrinking Water Catchments Regional Environmental Plan No 1). Under the SEPP,proposed developments in the drinking water catchment that need consent under acouncils local environmental plan must have a neutral or beneficial effect (NorBE) onwater quality, and should incorporate current recommended practices or performancestandards endorsed or published by the SCA related to water quality.

A neutral or beneficial effect on water quality means development that:

has no identifiable impact on water quality, or

will contain any water quality impact on the development site and stop it from

reaching any watercourse, waterbody or drainage depression on the site, or

any water quality impact outside the site where it is treated and disposed of tostandards approved by the consent authority.

The Neutral or beneficial effect on water quality assessment guideline 2011 (SCA,2011c) gives clear instructions about the meaning of the neutral or beneficial effect,how to show it, and how to assess an application against the NorBE test.

Councils and the SCA use the NorBE test to assess development applications in thedrinking water catchment. Developments are sorted into different developmentclasses, consistent with the Standard Instrument Principal Local EnvironmentalPlan. The development classes are then grouped into modules, based on thenecessary development assessment process and the level of potential risk from thedevelopment. For example, Module 1 developments usually involve a sewered newsingle dwelling, considered to be a lower risk to water quality. Module 4developments are considered to be a high risk to water quality and are typically ruralsubdivisions with construction of dwellings, subdivision roads and on-site wastewaterdisposal.

The questions and thresholds used to assess development applications are includedin the NorBE assessment tool, a web application that helps councils decide whethera development has a neutral or beneficial effect on water quality and whether theSCA has a concurrence role. The NorBE Tool also records the decision process foreach development application. The SEPP makes it mandatory for councils to use the

NorBE Tool to undertake their NorBE assessments.


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You can find more information about the SEPP and the NorBE assessment guidelineon the SCA website atwww.sca.nsw.gov.au.

Figure 1: Drinking Water Catchment
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Model development control plan clause

The SCA has developed a model clause for catchment councils to include in theirdevelopment control plans. The clause describes the need for all developmentapplications in the drinking water catchment to include a water cycle management

study, with relevant reports and modelling. Councils will progressively include theclause in all development control plans that cover the drinking water catchment. Therelevant reports and model are described according to the type and scale of thedevelopment proposal.

This document will be referred to in the drinking water clause of relevant localdevelopment control plans and should be read together with those plans. It describesthe SCAs requirements. Development applicants should also consider any otherrequirements of the relevant local environmental plan and development control plan.

The SCA recommends applicants engage a suitably qualified consultant or specialistto complete the water cycle management study, especially for intensive and high riskdevelopments that need detailed information.

2. The water cycle management study

All development applications in the drinking water catchment must include a watercycle management study to help council and the SCA assess whether thedevelopment will have a neutral or beneficial effect on water quality.

The study must include information, reports and modelling appropriate to the type ofdevelopment and the risks the development has for water quality. Higher riskproposals require more in-depth studies. The water cycle management study mustalso include information about erosion and sediment control, and detailed information

and reports about stormwater management and wastewater management in anyunsewered area.

Table 1 summarises the requirements that are described in detail below.

Table 1 Information requirements for water cycle management studies

Development typeInformation required in the Water CycleManagement Study

Minor developments of very low risk to waterquality - limited to very minor changes andadditions to residential houses in seweredareas

An assessment, consistent with the SCAsNeutral or beneficial effect on water qualityassessment guideline, of whether thedevelopment will have any identifiablepotential impact on water quality - if there areany potential impacts, the development mustinclude the information outlined in Module 1

Module 1

Less complex developments that are a minorrisk to water quality - typically includes newsingle dwellings, dual occupancy ortownhouses, multi-dwelling housing (threedwellings or less), subdivisions (three lots orless), or changes and additions to existingdwellings, in sewered areas

Modelling using the small-scale stormwaterquality model (SSSQM)

Conceptual erosion and sediment controls tobe used during construction


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Module 2

Less complex developments that are amedium risk to water quality - typicallyincludes new single dwellings, dualoccupancy or townhouses, or changes and

additions to existing dwellings, in unseweredareas

Modelling using the SSSQM

Conceptual erosion and sediment controls tobe used during construction

On-site wastewater management report

Module 3

Moderately complex developments that are amedium to high risk to water quality typicallyincludes multi-dwelling housing (more thanthree dwellings) and residential subdivisions(more than three lots) in sewered areas

Stormwater quality modelling (using eitherthe SSSQM or the MUSIC stormwaterquality model, depending on the size of thedevelopment)

Conceptual erosion and sediment controlplan or a more detailed conceptual soil andwater management plan

Module 4

Moderately complex developments that are ahigh risk to water quality typically includesmulti-dwelling housing and residentialsubdivisions in unsewered areas.

Stormwater quality modelling (using the

SSSQM or the MUSIC stormwater qualitymodel, depending on the size of thedevelopment).

Conceptual erosion and sediment controlplan, primary erosion and sediment controlplan or a more detailed conceptual soil andwater management plan.

On-site wastewater management report.

Module 5

Highly complex or non-standarddevelopments that are the highest risk towater quality - typically major industrial andcommercial developments, agriculturedevelopments such as intensive livestockfarms and intensive plant growing, extractiveindustries, and tourism and recreationaldevelopments

Stormwater quality modelling (using eitherthe SSSQM or the MUSIC stormwaterquality model, depending on the size of the

development)

Conceptual soil and water management plan

On-site wastewater management report (ifrelevant)

Development specific pollutant assessmentrequirements

3. General information requirements

General information needed to properly assess a development application includes,but is not limited to:

a clear outline of the development proposal, including a detailed site planincluding site constraintscopies of either a Statement of environmental effects or an Environmentalimpact statementa site contamination report, if relevantthe flood planning level for the development site, if relevant

a summary and location of the water quality control measures proposed aspart of the development

other information that must be supplied with a development application undercurrent planning provisions.


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Certification

A development application must include a signed statement by the relevantconsultant for each water cycle management study that certifies:

Stormwater

that the type, design, size and location of all proposed and modelledstormwater management measures are in the report and can be practicallyimplemented at the nominated locations

that the report meets all the requirements of this document and is consistentwith the SCAs draft Guide to the use of MUSIC in Sydneys drinking watercatchment (SCA, 2011a) or the SCAs draft Guide to the use of SSSQM inSydneys drinking water catchment (SCA, 2011b).

Wastewater

that the type, design, size and location of the proposed wastewater treatmentand effluent management area are in the report and can be practicallyimplemented on the site

meets all the requirements of this document

is consistent with the SCAs draft Design and installation of on-site wastewater systems (SCA, 2011d)

Generally

that the water cycle management study addresses all water quality matters

that the study addresses and includes where appropriate SCA endorsedcurrent recommended practices

that the study has a statement, based on the information included, aboutwhether the development will have a neutral or beneficial effect on waterquality, consistent with the SCAs Neutral or beneficial effect on water qualityassessment guideline 2011 (SCA, 2011c).

4. Erosion and sediment control measures

Depending on the size of the development proposal, a water cycle managementstudy must include either:

a plan for standard erosion control measures consistent with the Blue BookVolume 1 (Landcom, 2004) where the construction area of a proposeddevelopment is less than 250 square metresa level one conceptual Erosion and sediment plan, which addresses erosionand sediment control of a proposed development during a construction phasewhere 250 to 2,500 square metres of land will be disturbed. The plan doesnot address ongoing or permanent control of pollutants. The plan should be

consistent with the Blue Book Volume 1 (Landcom, 2004) and the BlueBook Volume 2 (DECC, 2008), OR

a conceptual soil and water management plan that describes what will bedone at the development site to control soil erosion (including sedimentation)and nutrient movement to downslope lands and receiving waters during andafter development. It also includes all the information included in an erosionand sediment control plan. There must be a soil and water management planfor all developments where the disturbed area will be more than 2,500 squaremetres. A multi-part erosion and sediment control plan (comprising primaryand progressive plans) allows for operational flexibility to plan appropriatecontrol measures, OR


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a multi-part erosion and sediment control plan (comprising primary andprogressive plans) that allows for operational flexibility to plan appropriatecontrol measures.

The soil and water management plan/ erosion and sediment control plan must beconsistent with the Blue Book Volume 1 (Landcom, 2004) and the Blue BookVolume 2 (DECC, 2008).

5. Stormwater requirements

The information requirements about stormwater must be addressed by either:

a certificate from an assessment completed using the small-scale stormwaterquality model, for simpler developments that are a minor risk to water quality -this includes new single dwellings, dual occupancy or multi dwelling housing,or changes and additions to existing dwellings in either sewered orunsewered areas - the small-scale stormwater quality model is available on

the SCA website atwww.sca.nsw.govOR

an outputs report and electronic copy of a completed model for urbanstormwater improvement conceptualisation (MUSIC) using the latest versionof the model.

MUSIC model and report

The model for urban stormwater improvement conceptualisation (MUSIC) is used formore complex developments that are a medium to high risk to water quality. Theseinclude larger urban sewered subdivisions, rural subdivisions in unsewered areas,developments with a large impervious area (more than 70 percent of the total site

area or 2,500 square metres), developments where a significant amount of land isdisturbed (more than one hectare), subdivisions of four or more lots, anddevelopments on highly constrained sites.

The report should include details of the site and development, and details about theproposed stormwater management and offset measures. The report should alsoinclude a statement of the assumptions used in the MUSIC model and implicationsfor the neutral or beneficial effect on water quality test. Key assumptions about landuse change, such as retaining native vegetation, should be included, as well as anyproposed maintenance and protection measures.

The MUSIC model should use climatic data provided by the SCA relevant to thelocation of the proposed development. If this is not available, you may use five years

of six-minute rainfall data for a nearby location that has at least 20 years of records.The five years must include a number of average years as well as the wettest yearon record.

The model needs to realistically represent the site before and after development, anduse appropriate source and treatment nodes for the land uses being simulated,including appropriate pollutant concentrations and realistic impervious areapercentages. It must use design parameters for treatment nodes based onappropriate hydraulic sizing and treatment effectiveness. An electronic copy of theMUSIC model must be included.

Note: Users of the MUSIC model must refer to the SCAs draft Guide to the use ofMUSIC in Sydneys drinking water catchment (SCA, 2011a) for a complete

description of the information needed. Any changes to the recommendations in the
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guide, including using any non-default parameters in the model, must be clearlyexplained and justified.

Site development details

Site and development details include:

a clear and complete description of the proposal, including the likely nature ofany future uses, and suitably scaled site plans in the context of siteconstraints

site features including surface and subsurface hydrology, existing erosioncontrol measures and any constraints or opportunities for water cyclemanagement

information about surrounding land uses where this may impact onstormwater management or it has high environmental value

an accurate description of the current situation showing the management ofexisting drainage in relation to contours or topography

site land use changes, including an accurate description of the changes fromthe development, including buildings, vegetation clearing and hardstandareas

an accurate description of the location, size and imperviousness of each landuse change, how future drainage will be configured and where discharges willhappen

the location of all proposed water management structures, devices and flowlines, and any offset measures such as erosion gully rehabilitation

any potential future water quality or quantity issues including impacts on

watercourses and riparian zones.

Proposed stormwater management

The report must include all details about the proposed stormwater managementmeasures, including information about:

the proposed stormwater management measures that are appropriate for thesite and soil, the scale and nature of the development, and the location of themeasures to maximise the volume of stormwater treated

details of the specific design elements, including the hydraulic basis for sizing,to ensure they can treat most runoff from the site before discharge

whether the proposed treatment measures can be practically implemented inthe proposed location on the development site, including adequate space andappropriate location. They should not impact on, or be impacted on, by theoperation of the site or their need for maintenance

appropriate design parameters to ensure the sizing, functioning and detentiontimes are hydraulically sound

the life span and ongoing management, maintenance and costs to ensurethey will not require excessive and unrealistic maintenance from thoseresponsible for ongoing management eg road reserve gross pollutant trapsthat are often dedicated to councils

any specific requirements to protect proposed stormwater managementmeasures.


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Proposed offset measures

The report should include all details about any proposed offset managementmeasures, including:

the nature, size, location and timing of these measures, including

revegetation of pasture land or erosion gully rehabilitation, and how theirsuccess is ensured eg survival rate of plantings

the specific measures needed to maintain and protect rehabilitation or offsetmeasures.

Modelling results

The modelling results must compare annual pollutant loads before and afterdevelopment. They must show an improvement of at least 10 percent to ensure theneutral or beneficial effect on water quality requirement can be met given theuncertainty in the modelled outcomes.

The modelling results must compare cumulative frequency curves of pollutant

concentrations before and after development. They must show that pollutantconcentrations after development will be better or equal to previous pollutantconcentrations at least 98 percent of the time.

6. Wastewater reports

The information requirements about wastewater must be addressed in a Wastewaterreport, which must include the following:

the specific details of the proposed wastewater treatment and effluentdisposal system being applied for, including the proposed site of the effluent

management area. You cannot provide an options report that shows a rangeof treatment systems and effluent management areas but does notrecommend a specific system

the appropriateness of the proposed system for the frequency of use,availability of power, slope, soils and other site constraints as specified below

a site map showing the site constraints and the site of the proposedwastewater treatment system and effluent management area in relation to keyconstraints and buffers

consideration of the physical practicality of a proposed gravity-fed systemgiven the site slope and grade and whether a pump well may be needed.

Appendix 2 of the Department of Local Governments On-site sewagemanagement for single households (the Silver Book) provides anappropriate template for wastewater reports. The report should refer tocurrent references and standards eg AS/NZS 1547:2000 On-site domesticwastewater management.

Wastewater loading

For a proposed dwelling (including dual occupancies) the report must include adesign wastewater loading determined using the SCAs Neutral or beneficial effecton water quality assessment guideline (SCA, 2011a) based on:

the number of potential bedrooms


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the nature of the water supply ie whether the dwelling is connected to town /bore water or is supplied by tank water

the wastewater loading per bedroom based on the nature of the water supply(Table 2)

For a non-dwelling proposal the report must include wastewater loading based onAS/NZS 1547:2000 On-site domestic wastewater management and / or the NSWHealths Septic tank and collection well accreditation guideline 2001 or otherreference source endorsed by the SCA.

The minimum septic tank size for residential developments is 3,000 litres. Larger tankcapacities must be based on design wastewater loads detailed in Table 4.3A1 inAS/NZS1547:2000. Where a spa bath is proposed as part of a development, theminimum septic tank size must be increased by 500 litres.

Table 2: Wastewater loading calculations

1-2

bedrooms

3

bedrooms

4

bedrooms

5 or more bedrooms

Tank water supply 400L/day 600L/day 800L/day100L/day extra for eachadditional bedroom

Reticulated / boresupply

600L/day 900L/day 1200L/day150L/day extra for eachadditional bedroom

For greywater-only systems a value of 65 percent of the design wastewater loadcalculated above should be used. Otherwise greywater systems are treated exactlythe same as other wastewater systems.

Site constraints map

The report must include a site map identifying all surface constraints, including:

the drainage network, including named rivers, watercourses, drainagedepressions and dams, roadside and other open drains (that are treated thesame as drainage depressions). In unsewered village areas this may need tobe discussed with the SCA

vegetation and shading/exposure

orientation

any poor drainage/wet seepage areas and springs

river flats/ floodplains or flood planning levelany groundwater bores located within 100 metres of the effluent managementarea and their use

existing wastewater management structures and effluent management areas

slope (percentage or degrees)

general landform

areas of run-on

rock outcrop and geology

stormwater management structures


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all existing and proposed structures including buildings, access ways orroads, livestock yards

buffer distances (see later)

exposed soil / erosion potential / fill etc.

Soil information

The report must include soil profiles of up to at least one metre (where possible)taken at the specific locations of the proposed effluent management areas,consistent with AS/NZS 1547:2000 On-site domestic wastewater management. Thereport must describe:

the soil texture and structure with depth using standard soil descriptions asper AS/NZS 1547:2000 - weathered and decomposing rock of the C Horizonis not considered part of the soil profile for effluent disposal consideration

the dispersibility (soil with an Emerson aggregate test class 1 are notgenerally suitable for effluent disposal (Van de Graff and Patterson, 2001))

other relevant chemical or physical characteristics that could impact onsustainable effluent disposal eg impeded drainage, as identified in the SilverBook or AS/NZS 1547:2000.

The report should also include the following where they are relevant to the site:

electrical conductivity/salinity (soil with more than 8 dS/m are not suitable foreffluent disposal unless the soil is treated)

sodicity (soils with more than 10 percent exchangeable sodium percentage(ESP) are not suitable for effluent disposal unless the soil is treated)

for permeable sandy or granitic soils, weighted phosphorus sorption values

for the soil profile, but only where effluent irrigation is proposed

monthly rainfall and evaporation data.

Available soil data is broad scale and should be confirmed with soil testing.

Climatic information

You must consider rainfall and evaporation data for the site and the implications forthe nature and size of the effluent management area. This information is available onthe SCAs website atwww.sca.nsw.gov.au.

You should also consider the impact of severe and prolonged frost where relevant.

General evaluation

Where an existing system will be upgraded or augmented, the location, nature,size/capacity, condition, and disposal area, of the existing on-site wastewater systemmust be clearly specified. For example this would include the size and condition ofthe septic tank, inspection and access ports, vents, and pipe connections, baffle walland inlet and outlet baffles, the septic tanks current state in terms of sludge depth,scum level, and the number, length, width and state of the absorption trenchesinspection ports.

Where tanks or effluent management areas do not meet current standards they mustbe replaced.
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Where an existing effluent management area will be upgraded the report must clearlyidentify the proposed upgrade including the extra or expanded area (in squaremetres) needed.

The report must consider whether the development will need a higher capacity pumpif the effluent will be pumped uphill and/or over substantial distances. It should also,

for example, nominate a suitable diameter (eg 32 mm) high-pressure poly pipe fittedwith non-return valves.

You must consider the location and nature of the effluent pipe from an aeratedwastewater treatment system or pumpwell to the effluent irrigation area. These pipesshould be buried at least 300 mm and in a way that protects them from mechanicaldamage or deformation.

Where a proposed effluent irrigation area has separate locations and/or differentelevations the report must identify specific hydraulic design requirements to ensurethe system will work effectively.

Effluent management area sizing

Absorption trenches and beds, and evapotranspiration absorption beds, must besized based on the design wastewater load and site soil characteristics as perAS/NZS 1547:2000. For primary treated effluent, the conservative design loadingrate must be used.

For sand mounds, sizing should be based on J.C. Converse and E.J. TylersWisconsin mound soil absorption system: Siting design and construction manual(University of Wisconsin-Madison; 2000). Simply applying the design loading rates inTable 4.2A of the AS/NZS 1547:2000 is not appropriate to size mounds.

The irrigation area for surface and subsurface effluent irrigation must be the largestarea for the design wastewater load and site soil characteristics determined by

hydraulic, nitrogen and phosphorus loadings as per AS/NZS 1547:2000 and theSilver Book.

The phosphorus sorption values used in the phosphorus loading example in theSilver Book must not be used, as the phosphorus sorption value is not typical ofmost locations. The weighted phosphorus sorption values relevant to the soil profileat the specific site for the effluent irrigation area must be used to determine the sizeof the effluent irrigation area based on nutrient balance. Most soils (excluding sandyand granitic soils with a low clay content) will have a phosphorus sorption value in therange 150-500 mg/kg, with a typical value of around 300 mg/kg. Basalt soils typicallyhave a range of 500-800 mg/kg and a typical value of around 600 mg/kg. Highlypermeable sandy or granitic soils have phosphorus sorption values in the range of 0-150 mg/kg with a typical value of 75 mg/kg.

Phosphorus sorption data in mg/kg is converted to kg/ha by using the followingequation:

0.01 x

Soildepth

(m)

x

BulkDensity

(kg/m3)

XPsorp

(mg/kg)

For amended soil mounds the size must be decided by the design wastewater loadand the design loading rate for the lowest depth soil at the upslope side of the bench

for the mound.


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Site plan for location of effluent management area

The report must include a site plan that clearly shows the location of the proposedeffluent management areas in relation to:

buffer distances to named rivers and water supply reservoirs (150 metres),

watercourses (100 metres), drainage depressions and dams (40 metres).These drainage features are not simply the blue lines as shown on contourmaps, but should be mapped for the site. Open roadside drains should betreated as drainage depressions. In unsewered village areas you may need todiscuss this with the SCA

any nearby groundwater bores on the site or nearby adjoining properties.Where a bore is within 100 metres of a proposed effluent management area itmust include a statement from the owner that the bore is not used for potabledomestic water supply or must have a groundwater drawdown analysis doneusing an appropriate methodology, such as Cromer, Gardner and Beavers,2001 An improved viral die-off method to estimate setback distances.

setback distance to property boundaries, buildings and other infrastructure(existing and proposed) as per Table 5 of the Silver Book

the site plan must show the location of any existing wastewater system tanks,piping and effluent management area that will be augmented ordecommissioned, or where these systems are located close to a newwastewater management system.

The site plan must be sufficiently clear to allow an assessor to accurately locate theproposed effluent management area.

Effluent irrigation

The SCA will require subsurface irrigation using either a capillary or wick-basedsystem, or pressure compensating drip emitters with root barriers, if:

average annual rainfall is more than 1,200 mm

neighbouring dwellings are close to the effluent management area

the effluent management area slope is more than seven percent (fourdegrees)

the effluent irrigation area needs to be regularly mowed to remove nutrientsfor long-term sustainability

there are regular severe and prolonged frosts (a summer surface / winter-subsurface hybrid system may be acceptable), or

council requires subsurface irrigation.

Where surface irrigation is proposed, the SCA will not accept moveable hoses,including semi-fixed systems. Developments will need fixed sprinkler points usingpop-up sprinklers (except for lawns or gardens close to the dwelling), or quickcoupling valves or similar with sprinklers to be rotated throughout the effluentirrigation area.

Sprinkler kits and hoses supplied by most aerated wastewater treatment systemmanufacturers are not suitable or acceptable.

Special considerations

The SCA will require all effluent management areas to be fenced off from livestock orvehicles. Where it is on a house block that livestock cannot access, the effluent


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management area must still be protected from vehicles but means other than fencingmay be acceptable.

The SCA will not accept:

a trench system longer than 200 metres

absorption systems where the soil is medium or heavy clay

absorption systems where there is less than 0.75 metres of soil

trenches more than 20 metres long, except where they are made of twoseparate inline trenches with a central feeder or where trenches are pressuredosed from a pump well (in these cases, the applicant should considerabsorption beds)

amended soil mounds on slopes of more than seven percent (four degrees).The SCA may, in exceptional circumstances, consider amended soil moundsfor slopes that are more than 7-10.5 percent (4-6 degrees) if the moundbench is built up with topsoil and is not cut into the slope

solar powered systems where continuous power is needed for normaloperation such as aerated wastewater treatment systems. The SCA may, inexceptional circumstances, accept solar power for those systems (eg someworm farms) where power is only periodically required to empty an effluentsump, if a detailed analysis is supplied of the power consumption of the pumpoperation in relation to a proposed power source and storage. These will onlybe considered on a case-by-case basis.

reed bed systems to treat and dispose of effluent except in exceptionalcircumstances. This will only be considered on a case-by-case basis. If thedesign is based on peak loads, the calculated size of the reed beds would betoo large for sustainable vegetation growth in the drier parts of the drinking

water catchment. The nutrient uptake of the vegetation is less in colderclimates, and in high rainfall areas system overflows can be a problem.

pump-out systems for domestic situations, except where a location willprobably be sewered in the near future. Pump out systems are notsustainable and are often the worst performing on-site systems due to misuseand poor practices. They may be considered in exceptional circumstances,however this will only be on a case-by-case basis where effluent disposal ona heavily constrained site, such as a manned pumping station on the steepbanks of a river, is not practicable, or where council does not allow on-siteeffluent disposal below a certain lot size, or the area is not and will not beserviced by a reticulated sewerage system. Where pump-out systems are

approved they must be:- large enough for the development (minimum tank size for domestic

systems/ residential purposes of 4,500 litres). Collection wells for aneffluent pump-out system that relies on total water harvesting must besized according to Table 2. Wells that rely on reticulated or bore watersupply must be sized according to Table 3 (BMCC, Better Living DCP)

- appropriately designed and/or anchored, eg tank and lid have anappropriate weight that ensures no tank buoyancy problems

- equipped with an indicator for wastewater level and an alarm for excesswastewater levels

-equipped with a readily accessible pump-out stand with a Kamlock (orsimilar) cover


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- equipped with a small spillage well with a valve for the pump-out pipe

- pumped out regularly by a pump-out contractor.

Where an existing wastewater treatment system is to be decommissioned it must bedone according to the NSW Health Advisory Note No 3 (dated 3 May 2006) forDestruction, removal or reuse of septic tanks, collection wells, aerated wastewatertreatment systems and other sewage management facility vessels(www.health.nsw.gov.au).

Applicants should also be aware of council requirements for wastewater disposal.

Table 2: Collection well sizes water harvesting (based on fortnightly pump-outs)

Number of bedrooms Collection well size (L)

3 10,000

4 14,000

5 16,000

6 20,000

Table 3: Collection well sizes reticulated or bore water (based on fortnightlypump-outs)

Number of bedrooms Collection well size (L)

3 13,000

4 18,000

5 21,000

6 26,000

7. More information

The SCA and councils will use information from the water cycle management study

to assess the proposal and set conditions. Where necessary, the SCA and councilswill assess proposed unsewered developments using the SCAs Wastewatereffluentmodel to ensure that effluent can be contained on-site and will not intersect with thedrainage network.

Modelling results may require relocation of an effluent management area or analternative treatment and/or disposal system.

More information and help are available by contacting the SCAs Planning andAssessments Team at [email protected], or on 1300 722 468.
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8. Glossary

Catchment An area of land where water from rain and melting snow or icedrains downhill into a body of water, such as a river, lake,reservoir or wetland.

Conceptualerosion andsediment controlplan

A conceptual ESCP addresses erosion and sediment controlduring a construction phase where 250 to 2500 square metreswill be disturbed. It contains the methods to be used and theirlocation.

Conceptual soiland watermanagementplan

A conceptual SWMP addresses erosion and sediment controlduring a construction phase where more than 2500 squaremetres will be disturbed. It contains the methods to be used,their location, size and timing.

Consentauthority

(In the EP&A Act), in relation to a development application or anapplication for a complying development certificate, means:

(a) the council having the function to determine the application,or

(b) if a provision of this Act, the regulations or an environmentalplanning instrument specifies a Minister or public authority (otherthan a council) as having the function to determine theapplicationthat Minister or public authority, as the case maybe.

Development (a) the use of land, and

(b) the subdivision of land, and

(c) the erection of a building, and

(d) the carrying out of a work, and

(e) the demolition of a building or work, and

(f) any other act, matter or thing referred to in section 26 that iscontrolled by an environmental planning instrument, but doesnot include any development of a class or description prescribedby the regulations for the purposes of this definition.

Developmentapplication

An application for consent under Part 4 of the EP&A Act to carryout development but does not include an application for a

complying development certificate.

Drainagedepression

A low point that carries water during rainfall events, but dries outquickly once rainfall has ceased. A gully or incised drainagedepression is considered to constitute a watercourse.

Potentialbedroom

Generally a room with a closable door, at least one window anda minimum of 8 square metres. A room in a separate buildingsuch as a studio could be considered if it has a toilet andwashing facilities or close access to same. A room that couldreasonably be used as a bedroom.


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Primary erosionand sedimentcontrol plan

The primary ESCP is a broad-based framework that outlines theintentions and fundamental principles that will be followed inplanning and implementing control measures for an entireproject. The primary ESCP is prepared as a document andusually includes standard drawings of control measures that are

suitable for the site(s) and to be used in the project. It is oftensupplemented with a series of subordinate progressive ESCPs(Blue Book Vol.s 2C and 2D).

Progressiveerosion andsediment controlplan

Progressive ESCPs detail the specific location and type ofindividual erosion and sediment control measures along theproject. These should be consistent with the approach outlinedin the primary ESCP, referencing standard drawings in theprimary ESCP as appropriate (Blue Book Vol.s 2C and 2D).

Quality of water Quality of water refers to the surface water and groundwaterquality of the catchments, and does not just mean quality for

drinking purposes. Issues of concern extend beyondCryptosporidium and Giardia; water quality can be affected bychemical, biological and physical factors.

In undertaking an environmental impact assessment,assessment of the potential impacts of the development on thequality of water refers to the existing water quality of receivingwaters, whether degraded or not. As water quality varies,existing water quality is usually reflected as an average or rangeof measurements taken over time. In some cases, because ofinsufficient background information, it may be prohibitively costly(in terms of time and money) to scientifically determine the

existing water quality. The assistance of specialist agenciessuch as the SCA and DECCW will be drawn on in such cases.

Sediment Material of varying size that is being, or has been moved from itssite of origin by the action of wind, water or gravity and comes torest on the earths surface, including within waterbodies.

Severe frosts Areas of severe frost are defined as those where the overnightminimum air temperatures (Stephenson screen) are regularlybelow -3oC, corresponding to a ground temperature ofapproximately -5oC. Note that frost hollows and areas of cold airdrainage may result in localised areas where frost is more

severe than indicated by temperature records for the region.

Site The site of a proposed development means the area of landdescribed in the development application.

Stormwater Rainwater running off a surface.

Waterbody(artificial)

An artificial body of water, including any constructed waterway,canal, inlet, bay, channel, dam, pond, lake or artificial wetland,but does not include a dry detention basin or other stormwatermanagement construction that is only intended to hold waterintermittently.


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Waterbody(natural)

A natural body of water, whether perennial or intermittent, fresh,brackish or saline, the course of which may have been artificiallymodified or diverted onto a new course, and includes a river,creek, stream, lake, lagoon, natural wetland, estuary, bay, inletor tidal waters (including the sea).

Watercourse Any river, creek, stream or chain of ponds, whether artificiallymodified or not, in which water usually flows, either continuouslyor intermittently, in a defined bed or channel, but does notinclude a waterbody (artificial).

Weighted Psorpvalue

The weighted value is similar to an arithmetic mean, but eachdata point contributes equally to the final value.

Example of weighted average of phosphorus sorption of soilprofile

Soil Depth

(cm)

Psorption(mg/kg)

Psorption / soil layer

0-10 150 10 x 150 = 1,500

10-30 200 20 x 200 = 4,000

30-100 400 70 x 400 = 28,000

WeightedPsorp

=(1,500 + 4,000 + 28,000)

10 + 20 + 70= 335 mg/kg


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9. Acronyms

CRP Current recommended practice

DECCW Department of Environment, Climate Change and Water (includingthe former DECC, the Department of Environment and ClimateChange)

DCP Development control plan

DLR Design loading rate

EP&A Act Environmental Planning and Assessment Act 1979

EMA Effluent management area

ESCP Erosion and sediment control plan

FPL Flood planning level

LEP Local environmental plan

MUSIC Model for urban stormwater improvement conceptualisation

NorBE Neutral or beneficial effect (on water quality)

SCA Sydney Catchment Authority

SEPP State Environmental Planning Policy (Sydney Drinking WaterCatchment) 2011

SSSQM Small-scale stormwater quality model

SWMP Soil and water management plan

WCMS Water cycle management study

WEM Wastewater effluent model


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10. References

1. Converse JC and Tyler EJ, Wisconsin Mound Soil Absorption System: SitingDesign and Construction Manual, University of Wisconsin, Madison, 2000.

2. Cromer WC. An Improved Viral Die-Off Method for Estimating SetbackDistances, Proceedings of On-site 01 Conference: Advancing On-siteWastewater Systems, University of New England Armidale, 15-27 September2001.

3. Department of Environment and Climate Change (NSW), Managing UrbanStormwater: Soils and Construction, Vol. 2, DECC, Sydney, 2008 (the BlueBook Vol.2).

4. Department of Local Government, On-site Sewage Management for SingleHouseholds, DLG, Sydney, 1998 (the Silver Book).

5. Department of Planning (NSW), Standard Instrument Principal LocalEnvironmental Plan 2006, DoP, Sydney, 2006.

6. Landcom, Managing Urban Stormwater: Soils and Construction, Vol. 1, 4th Ed,Landcom, Sydney, 2004 (the Blue Book Vol.1).

7. NSW Health, Advisory Note No 3 Destruction, Removal or Reuse of Sep ticTanks, Collection Wells, Aerated Wastewater Treatment Systems and OtherSewage Management Facility Vessels, NSW Health, Sydney, 2006.

8. NSW Health, Septic Tank and Collection Well Accreditation Guideline (Septic

Tanks, Collection Wells, Septic Closets (Blackwater Tanks), Greywater Tanks,CED Pretreatment Tanks, and Sewage Ejection Pump Stations) Part 4, LocalGovernment (Approvals) Regulation, 1999, NSW Health, Sydney, 2001.

9. Standards Australia, Australian/New Zealand Standard 1547:2000 On-sitedomestic wastewater management, Standards Australia (Strathfield) andStandards New Zealand (Wellington), 2000.

10. Sydney Catchment Authority, Guide to the use of MUSIC in Sydneys drinkingwater catchment, SCA, Penrith, 2011a (in draft).

11. Sydney Catchment Authority, Guide to the use of SSSQM in Sydneys drinkingwater catchment, SCA, Penrith, 2011b (in draft).

12. Sydney Catchment Authority, Neutral or beneficial effect on water qualityassessment guideline 2011, SCA, Penrith, 2011c.

13. Sydney Catchment Authority, Design and installation of on-site waste watersystems, SCA, Penrith, 2011d (in draft).

14. Van de Graff R and Patterson RA, Explaining the Mysteries of Salinity, Sodicity,SAR and ESP in On-site Practice, Proceedings of On-site 2001 AdvancingWastewater Systems, Lanfax Laboratories, Armidale, 2001.

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