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Ordinary Council Meeting
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2 July
2009
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Director Environment & Planning's Report
ITEM 10.3 SF1232 020709 Report on Review of Nambucca Shire Council - On-site Sewage
Management Plan
AUTHOR/ENQUIRIES: Neil Pengilly, Senior Health and Building Surveyor
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Summary:
Council will
recall dealing with a report at its General Purpose Committee on 17 December,
2008 in relation to a review of Council’s On-site Sewage Management Plan
1999.
Council
resolved that the draft Plan be placed on public exhibition and a further
report be prepared for Council’s consideration.
The draft
On-site Sewage Management Plan 2009 was subsequently placed on public
exhibition, being advertised within the Guardian
Newspaper, promoted on Council’s website and formally
notified to nine (9) on-site sewage management consultants and thirty-nine
(39) plumbing practitioners who operate within the Shire.
Submissions
were received from three (3) consultants and two (2) plumbing practitioners.
Copies of all submissions and a précis of the comments are attached. The main
issues raised within the submissions are discussed within this report
A copy of the
revised draft On-site Sewage Management Plan 2009 is also attached.
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Recommendation:
1 That
the draft Nambucca Shire Council On-site Sewage Management Plan 2009 be
adopted.
2 That
authors of all submissions be advised of Council’s resolution.
3 That the adopted plan be placed on
Council’s website with relevant fact sheets and checklists.
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OPTIONS:
Council has the
following options:
1 To adopt the draft On-site Sewage
Management Plan 2009, as recommended;
2 Require further modification of the
draft Plan prior to adoption; or
3 Resolve not to adopt the draft Plan.
DISCUSSION:
During the
consultation process, submissions were received from three (3) on-site sewage
management consultants and two (2) plumbing practitioners.
Whilst
appreciating that the design considerations are consistent for the assessment
of all on-site sewage management systems, the submissions show distinct
variation in their content and it is clear that different
consultants/practitioners have differing viewpoints as to the most appropriate
form of wastewater disposal.
Many matters
raised within the submissions related to minor amendments involving
clarification of requirements, revision of terminology and/or provision of
additional information. These amendments
have been addressed within the revised plan.
Other matters
raised are discussed as follows:
i) Exclusion of
absorption trenches for onsite disposal.
Two submissions
argue that the use of absorption trenches (normal septic tank installation)
within the Shire is not appropriate due to matters such as unsuitable soil
characteristics, lack of nutrient reuse and poor performance.
Comment:
Soil mapping
undertaken by the Department of Land and Water Conservation identifies many
soil profiles within the Shire as unsuitable for effluent disposal by
absorption due to a variety of considerations. The mapping, whilst being a
valuable tool in the initial assessment of potential systems, is a broad based
characterisation of soil profiles and does not indicate variations that may
occur within subject properties.
As part of
Councils assessment for installation of new systems a site and soil assessment
report, specific to the subject site, is required to be submitted. The report
includes details of the soil profile and characteristics at the location of the
proposed disposal area to assist in identifying any local variations from the
broad scale mapping. It is suggested that this site specific assessment
provides the best opportunity to optimise the final design/configuration of the
on-site system.
With respect to
nutrient reuse, it is acknowledged that other forms of disposal (e.g.
subsurface irrigation) are more efficient than absorption trenches. Where
nutrient uptake is the dominant limitation in the design of the disposal
system, the length of absorption trenching required to cater for the nutrients
may result in this form of disposal system becoming economically unviable.
However, nutrient loading is not always the dominate limitation and the broad
based exclusion of absorption trenches is not supported. It should be noted
that the use of absorption trenches will be further impacted by the design
criteria required under the draft Plan with other forms of disposal systems
becoming more viable.
ii) Surface
spray irrigation from aerated wastewater treatment systems (awts).
The
draft Plan prohibits disposal of effluent from awts by surface spray
irrigation. One submission, whilst agreeing with the intention of the
restriction, expressed concern that it may have implications within the awts
industry given that surface disposal is permitted under the NSW Department of
Health accreditation.
Comment:
The
accreditation provides for three forms of disposal, above ground spray
irrigation, surface drip irrigation covered by mulch and sub-surface drip
irrigation installed at around 100mm depth. The accreditation also states “Each
of the three forms of irrigation is subject to the approval of the Council”. As
such it is inferred that Council has the authority to refuse certain methods of
disposal. Physical separation between humans and effluent disposal is
considered a failsafe method in assisting to prevent the spread of disease.
Awts
are essentially a compact treatment plant that processes all domestic
wastewater from the premises to a tertiary standard (disinfection). There is a
concern that in the event of a system failure or where inspection and servicing
of the systems has been inadequate, surface spray of insufficiently treated
effluent will result in an unsatisfactory risk of human/effluent contact.
iii) Greywater
reuse/separation from blackwater.
Two submissions
identified concerns relating to the reuse/separation of greywater from
blackwater. The matter has resulted in much debate within the industry as to
the advantages/disadvantages of the system. The reuse of greywater was recently
approved by legislation however practitioners have raised concern relating to
its long term sustainability.
Comment:
The benefits of
reuse in relation to water conservation are undeniable, however the
characteristics of greywater includes high salt content which over time will
degrade the soils capability to accept the disposal of the wastewater. The salt
level can be reduced by osmosis. However, this process is not practical with
the systems currently available. Not withstanding, the Local Government
(General) Regulation, 2005 and the NSW Department of Health currently provides
opportunities for the diversion of greywater or reuse (after adequate
treatment) and these opportunities have been carried over within the draft
On-site Sewage Management Plan 2009.
iv) Concession
for upgrade of existing systems.
Under Section
9.3 of the draft Plan, existing systems that are failing are required to be
upgraded. One submission expresses concern that separate criteria is being
applied when compared with new systems.
Comments:
The Plan
requires the same considerations to be undertaken whether a new or existing
system is being addressed. Existing systems will only gain a concession where
compliance with new requirements is not physically possible (e.g. where a small
property does not permit the required buffers to be achieved).In these
circumstances additional measures will need to be incorporated to address the
identified deficiency.
A second
submission is concerned with how Council will determine who has “appropriate
knowledge and experience” when preparing assessments for upgrades of existing
systems.
Comment:
Existing systems
differ from new installations in that the performance of the existing system
provides a “history” as to how that particular design/configuration is suited
to the subject site. This “history” is not available for installations on new
properties. In this regard, Council will accept reports from suitably qualified
plumbers with local knowledge and experience. The report will still need to
assess similar criteria as for a new system. Council is still required to
assess such a report to ensure it achieves compliance with the Management Plan
and Regulations.
v) Ten (10) year
Approval to Operate not supported.
One submission
received states that from their experience “trench designs have failed after 7
to 18 years of system use”. The proposed Class 4 system would result in the
approval/inspection period being extended at a time when the wastewater
disposal area is nearing the end of its effective life.
Comment:
Under Council’s
Risk Evaluation (Section 12.1) it was proposed that where a Class 3 system (5
year Approval to Operate) had two consecutive satisfactory inspections the
system would be re-classified as a Class 4 (10 year Approval).
The intention of
extending the period to a 10 year approval was to reward system operators where
the system has a proven record of satisfactory performance and is located such
that any failure would have minimal environmental impact.
It is agreed
that all wastewater disposal systems have a finite life which is dramatically
influenced by various factors such as usage, design and environmental matters.
As such the proposed re-classification to Class 4 has been deleted from the
Management Plan. It is now proposed that the Class 3 systems will receive an
Approval to Operate for a period of 7 years. This will assist in reducing the
burden of inspection costs on the property owner while still monitoring the
wastewater system for effective over the critical period.
vi) Mandatory
inspection at change of ownership.
Two submissions
suggested that mandatory inspection/upgrade of existing systems be undertaken
where the subject property undergoes a change of ownership.
Comment:
The Regulations
currently require new owners to obtain an Approval to Operate an on-site sewage
management systems. When properties are placed on the market a Section 149
Zoning Certificate is required to be obtained. The Certificate identifies
whether the property has a current Approval to Operate and a Council form for
Change of Details is attached. This form and advice is also included on Council
Certificates relating to Outstanding Notices. When Council receives notice of a
change in ownership details, the exiting Approval to Operate is transferred
into the new owners name and the Approval continues to operate until its expiry
date occurs. Council does not “require” the system to be inspected if the
current Operating Approval is still valid. The purchaser may, at their
discretion, request Council to undertake an inspection of the system to
identify any deficiencies.
vii) Buffers
distances to relate to type of disposal system not level of treatment.
Section 11.2 of
the draft Plan outlines the requirements for buffer distances for effluent
disposal areas. The buffer distances originally related to the “type of
treatment” provided to the effluent but have now been amended to reflect the
“type of disposal system” utilised. This change provides consistency with the
Environment & Health Protection Guidelines.
viii) Inclusion
of soil mapping.
As mentioned
above the Department of Land and Water Conservation has produced a document
entitled “Soil Landscapes of the Macksville & Nambucca” which includes
detailed characteristics of soils found within the Shire. Whilst the maps
themselves have not been reproduced (due to logistical and copy right issues)
they have been referenced within the draft Plan. Council will further
investigate the possible provision of this information on Council’s website
subject to the relevant permissions being obtained.
ix) Improved
description/reference to reedbed systems.
Two submissions
raised concern relating to the description and references of reedbed systems as
described in the draft Plan.
Comment:
Additional
information has been included and the description of the system altered to
reflect that contained within the submissions.
x) Poor
inspection/assessment by Council.
One submission
was critical of Council’s efforts in relation to inspection and assessment of
on-site sewage management systems. Examples of systems reportedly failing and
being passed by Council were documented.
Comment:
Several of the
identified cases are known to Council however, from the comments made within
the submission it appears that the author was not aware of the full details.
The author was requested to provide property details of the case studies so
that Council could initiate further inquires. However, this advice was never
received. Notwithstanding, Council’s efforts in the assessment and inspection
of systems can be improved.
Documentation
required under the draft Plan will allow more critical analysis of a proposed
system. In addition the adopted design criteria is expected to result in more
durable systems that have a significantly increased lifespan.
CONSULTATION:
In accordance
with Clause 77 of the Local Government (General) Regulation 2005, the draft
On-site Sewage Management Plan 2009 was placed on public exhibition from 22
January 2009 until 13 March 2009.
The draft Plan
was advertised in the Guardian newspaper on 22 January 2009 and 19 February
2009, promoted on Council’s website and formal notification sent to nine (9)
on-site sewage management consultants and thirty-nine (39) plumbing contractors
who operate within the Shire.
Submissions were
received by Council until 13 March 2009.
From the
notification process, submissions were received from three (3) consultants and
two (2) plumbing contractors. Copies of all submissions are attached and the
issues raised are discussed within this report.
SUSTAINABILITY
ASSESSMENT:
Environment
The draft
On-site Sewage Management Plan provides a strategy to ensure that the on-site
disposal of domestic effluent occurs in a sustainable manner and with minimal
adverse impact upon the environment.
Social
There are no
social implications from this plan.
Economic
The cost of
installing, upgrading or replacing failed on-site systems places a financial
burden on the property owner.
Risk
Exposure to
litigation may occur where it is proven that Council has failed to meet its
statutory obligations. The implementation of this plan will assist in reducing
any such exposure.
FINANCIAL IMPLICATIONS:
Direct and indirect impact on
current and future budgets
The impact of the plan on current and future
budgets is generally neutral. A minor reduction in income may occur where the
frequency of inspections undertaken by Council are reduced. This reduction in
income will be off set by a reduction in expenditure via payment to Council’s
contractor undertaking the inspections.
Source of fund and any variance to
working funds
Funding is
derived from fees associated with the lodgement of applications and inspections
undertaken by Council.
Attachments:
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1View
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14228/2009 - Summary of Submissions - On-site
Sewage Management Plan 2009
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2View
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15112/2009 - Draft On-Site Sewage Management Plan
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3View
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4495/2009 - Submission/comments for Draft On-Site
Sewage Management Plan-Coffey Geotechnics
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4View
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6328/2009 - Submission for draft on-site sewage
management plan - Truewater Solutions
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5View
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6356/2009 - Submission for draft on-site sewage
management plan-John Craven
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6
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15301/2009 - submission - Rosewood Environmental
Services for Draft On-site Sewage Management Plan
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7
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15297/2009 - submission-Jim Ebert (Mid Coast
Reedbed Wastewater Systems) re Draft On-site Sewage Management Plan
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Ordinary Council
Meeting - 2 July 2009
Report on Review of Nambucca
Shire Council - On-site Sewage Management Plan
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Attachment
2
15112/2009
- Draft On-Site Sewage Management Plan
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1 EXECUTIVE
SUMMARY
This On-Site
Sewage Management Plan (strategy) was prepared in accordance with the
requirements of the Local Government (General) Regulation, 2005.
The plan relates to domestic wastewater
(non commercial/industrial activities) for on-site systems treating up to 2000
litres per day.
The Local Government Act 1993 requires all
on-site sewage management systems to be licensed by Council.
On-site sewage management systems (which
include septics, aerated wastewater treatment systems, composting toilets,
reedbeds, sand filters, biological filters, membrane reactors, greywater
systems, etc) are required in all non-sewered areas.
These systems treat wastewater from a
premise before being disposed of to an on-site land application area. Land
application areas may include absorption/evaporation beds, subsurface
irrigation or drip irrigation.
The Plan provides information to applicants
and the community about On-Site Sewage Management Systems and what must be
included in an application to install, modify or operate such a system.
On-site systems that are not performing
satisfactorily may lead to significant environmental and public health issues.
As such the long term viability and satisfactory performance of the system is
fundamental in minimising any potential adverse impacts.
2 LOCAL
CONTEXT
Nambucca Shire
Council is a medium sized coastal/rural Shire located on the Mid North Coast of
New South Wales. It comprises a mix of towns, villages, rural residential and
rural areas.
The Shire is
bounded generally to the north by Bellingen Shire and on the south and west by
Kempsey Shire. It is roughly triangular in shape, being 1,433km2 in
area with a coastline of approximately 20km. The Shire geographically
represents the catchment units for the Nambucca River
and its tributaries.
The Shire can be
divided topographically into two (2) broad areas. The western part comprises
the rugged topography of the eastern edges of the New England Plateau,
dominated by steep hill slopes and valleys with a significant area having
slopes in excess of 33%. The eastern part of the Shire is characterized by the
gentle slopes of the Nambucca
River and Taylors Arm
flood plains and adjacent undulating lands.
From the
elevation of 0.0 metres at the mouth of the Nambucca River
to approximately 900 metres in the western part of the Shire.
Much of the Shire
comprises steep land (60%), with the remaining areas undulating (20%) or flat
(20%). The most productive rural land is on the alluvial flats of the Nambucca River and its tributaries with some
grazing on undulating slopes. Agricultural production comprises 19% of the
total Nambucca area. Tourism and aquaculture make up a significant portion of
the economy of the area. The principle type of aquaculture within the shire is
oyster farming with leases along the Nambucca
River.
As at 19 November
2008 there were 2897 On-Site Sewage Management Systems registered with the
Nambucca Shire Council.
3 SCOPE
The Local
Government (General) Regulation, 2005, the State Government document entitled Environment & Health Protection
Guidelines – On-site Sewage Management for Single Households (which is
currently under review) and the Australian/New
Zealand Standard 1547 - On-Site Domestic
Wastewater Management (1994 & 2000) provide a framework for
implementation of ecologically and socially sustainable On-Site Sewage
Management practices. It is intended that this should be achieved, as far as
possible, by a process of community and user education and by implementation of
appropriate operating requirements in a manner that is sensitive to the local
circumstances. Strategic management of existing septic systems and attention to
address sewage management issues in new release areas is an important task for
Council. Sewage management strategies need to be linked with related strategies
for urban sewer services, and a greater emphasis placed on storm water and
pollution control.
Regulations
gazetted on 6 March 1998 require owners of relevant premises to apply to
Council for approval to operate and amend a system of sewage management. The
Council is required to grant an operating approval (eg, a sewer management
license). The granting of any such approval allows the Council to monitor
performance on a regular basis and to levy an inspection fee (frequency will
depend on area sensitivity) to cover reasonable costs.
4 AIMS
This management
plan is intended to:
¨ Provide a
framework to manage and regulate the impact of On-Site Sewage Management
Systems in the Nambucca Shire Local Government area and to ensure community
accountability.
¨ Assist Nambucca
Shire Council in prioritising resources for efficient regulation and monitoring
of On-Site Sewage Management Systems within the shire area.
¨ Co-ordinate environmental assessment, data collection and monitoring
which is related to On-Site Sewage Management.
¨ Allow for site assessment on risk management basis and consideration of
alternate solutions on environmentally sensitive sites.
¨ Provide opportunity for education of system users through ongoing
auditing programs.
5 OBJECTIVES
This plan has
been designed to achieve the following objectives:
¨ The protection of
surface water and ground water.
¨ The protection of
land and vegetation.
¨ Minimise the
health risk associated with On-Site Sewage Management facilities.
¨ Encourage the re-use of
resources eg the reuse of grey water after treatment through a council approved system.
¨ Promote
ecologically sustainable development.
6 GOALS
¨ To continue
building and maintaining a database of all On-Site Sewage Management Systems.
¨ To map and
maintain details of soil and site conditions and suitability for On-Site Sewage
Management Systems. The mapping overlay being placed on Council’s GIS and use
of this information in conjunction with site specific soil reports should
provide beneficial data for all new systems being installed.
¨ To ensure that
all land application areas comply with environmental and health protection
standards and Council operating requirements.
¨ To adopt a
partnership approach with householders and service agents to support continual
improvement of On-Site Sewage Management systems.
¨ To determine the
structures and facilities needed to support On-Site Sewage Management Systems.
¨ To ensure that
all On-Site Sewage Management Systems are inspected by qualified people at
regular intervals and are maintained as required.
¨ In co-operation
with householders, to develop a site specific Sewage Management Plan for each
household using an On-Site Sewage Management System.
¨ To review
Council’s development standards and approval criteria for subdivision,
development and building works to ensure that appropriate provision is made for
sustainable On-Site Sewage Management when residential development occurs in
non-sewered areas.
¨ To consult all
wastewater treatment system agents to ensure that maintenance reports certify
that the system’s operation and land application of effluent is being done in
compliance with the site requirements and constraints.
¨ To promote the
use of suitably qualified service contractors and consultants that are
acceptable to council. Such
contractors/consultants may be recognised on a regional basis.
¨ To ensure
appropriate land investigation and design of on-site sewage treatment and
disposal systems.
7 REVIEW
PROCESS
A review process
must be undertaken on a regular basis for the following reasons:
¨ To ensure that
the resources, structures and facilities are in place to support On-Site Sewage
Management Systems.
¨ To ensure that
references to guidelines, standards and legislative requirements are up to
date.
¨ Compare and
review the management plan against the previous years of implementation to
asses’ community concerns and any improvement that can be made to the plan.
¨ Refine and
enhance Council’s regulatory role in the management of On-Site Sewage
Management Systems.
¨ Provide improved
assessment standards and techniques.
This current
review has the benefit of eight (8) years, of implementation and the following
issues are being addressed as part of the review process:
¨ Upgrading of
existing systems that are not performing satisfactorily.
¨ The phasing out
of “long drop” toilets (pit toilets).
¨ Upgrade of
greywater systems on larger rural properties.
¨ Upgrade access to
tanks to ensure good maintenance and operation of the entire on-site system.
¨ Undertake ongoing
education of operators and owners of on-site sewage management systems.
¨ Identify
properties that have unregistered systems.
¨ Follow up on
systems installed with unauthorised land uses.
¨ Encourage
replacement of existing surface disposal systems from AWTS with subsurface
irrigation or dripper systems with suitable covering.
8 ADMINISTRATION
8.1 APPROVAL
Under Section 68
of the Local Government Act 1993, Council approval is required for the
installation, construction or alteration of a human waste treatment device or
storage facility and drains connected to it.
Council approval
is also required for the ongoing operation of an On-Site Sewage Management
System. Failure to obtain an approval or to comply with the conditions of an
approval are offences liable to a maximum penalty of twenty penalty units
(currently $2200).
An Approval to
Operate must be held by the property owner for any on-site sewage management
system. Where a change in ownership occurs, the new owner is required to obtain
an Approval to Operate from Council within three months of the change.
Clause 26 of the Local Government (General) Regulation 2005 sets out the
details that are to accompany an application for the installation of a sewerage
management facility with Clause 29 specifying the matters Council must take
into consideration when assessing an application to install or alter an on-site
sewage management system.
Council has
responsibility under the provisions of the Local Government Act to maintain a
register of On-Site Sewage Management Systems within their local government
area.
Local Government
therefore has responsibility to ensure that each approved system is maintained
and serviced correctly. Furthermore, Local Government has a legislative
responsibility to ensure that approved systems are installed and operated
according to approved specifications and any special conditions.
NOTE: A helpful fact sheet and checklist
containing specific details that must accompany an application is available
from the council either on-line or
from the Council’s Administrative Centre
8.2 NON COMPLIANCE
The failure to
operate or maintain a system in accordance with a Council approval or the
requirements of NSW Health may lead to operating licenses being
suspended/withdrawn, Orders issued or penalty notices being served.
8.3 LEGISLATION SCHEDULE
The following
Acts and Regulations contain provisions that are applicable to on-site sewage
management systems:
¨ Local Government
Act 1993
¨ Local Government
(General) Regulation 2005
¨ Protection of the
Environment Operations Act 1997
The commencement
date of the On-Site Sewage Management Legislation was the
6 March 1998 (date of the gazettal). The legislation provides that:
¨ Land owners with
On-Site Sewage Management facilities installed prior to the
6 April 1998 must apply to the Council to register their system and
for approval to operate a System of Sewage Management.
¨ New performance
standards for approvals to install, construct or alter an On-Site Sewage
Management facility apply from the 6 March 1998.
¨ Land owners who
install new On-Site systems after the 6 April 1998, must obtain
Council approval to operate a system of sewage management prior to the intended
date of occupation of the premises.
¨ Council’s were
required to adopt an approved fee for applications for approval to operate any
new system installed from 6 April 1998 by resolution and public notice
under Section 612 of the Local Government Act 1993. This fee is included in
Council’s Annual Management Plan.
8.4 AUSTRALIAN STANDARDS AND GUIDELINES
The relevant
Standards and Guidelines are as follows:
¨ AS/NZS
1546.1:1998 - On-site Domestic Wastewater Treatment Units – Septic Tanks
¨ AS/NZS
1546.2:2001 – Waterless Composting Toilets
¨ AS/NZS
1546.3:2001 - Aerated Wastewater Treatment Systems
¨ AS/NZS 1547:2000
– On-site Domestic Wastewater Management
¨ AS/NZS 3500:2003
– Plumbing and Drainage
¨ NSW Department of
Health - Certificates of Accreditation for Septic Tanks and Collection Wells
¨ NSW Department of
Health – Greywater Reuse in Sewered Single Domestic Premises, 2008
¨ Environmental
Health Protection Guidelines – On-site Sewage Management for Single Households,
1998
¨ Nambucca Shire
Council On-site Sewage Management Plan, 2009
8.5 PERFORMANCE
STANDARDS
Council must not
approve an application which would not comply with performance standards
prescribed by the Regulation and must take into consideration, relevant
guidelines and directions that have been issued by the Director General of
Local Government.
In 1998 the Local Government Act 1993 was
amended to include new regulations for On-site Sewage Management (OSSM)
Systems.
The current
regulations specify that On-Site Sewage Management Systems should be designed,
installed and operated to ensure the following environmental and health
performance objectives will continue to be met over the long term:
¨ Prevention of
health risk.
¨ Protection of
land.
¨ Protection of
surface waters.
¨ Protection of
ground waters.
¨ Conservation and
re-use of resources.
¨ Protection of
community amenity.
Clause 44 of the
Local Government (General) Regulation 2005, requires that a system of sewage
management must be operated in a manner that achieves the following specific
performance standards:
¨ the prevention of
the spread of disease by micro-organisms,
¨ the prevention of
the spread of foul odours,
¨ the prevention of
the contamination of water,
¨ the prevention of
degradation of soil and vegetation,
¨ the
discouragement of insects and vermin,
¨ ensuring that
persons do not come into contact with untreated sewage or effluent (whether
treated or not) in their ordinary activities on the premises concerned,
¨ the minimisation
of any adverse impacts on the amenity of the premises and surrounding lands,
¨ If appropriate,
provision for the re-use of resources (including nutrients, organic matter and water).
9 SEWAGE
TREATMENT AND DISPOSAL
9.1 TREATMENT
Wastewater
requires varying levels of treatment, depending on the method of disposal and
the sensitivity of the site. Treatment is generally classified as primary,
secondary or tertiary.
Primary treatment
is the separation of suspended material from wastewater by settlement and/or
flotation in septic tanks, primary settling chambers, etc prior to discharge to
either a secondary treatment process or to a land application system.
Secondary
treatment is generally an aerobic biological process involving the settling or
filtering of effluent from a primary treatment system and provides an improved
“quality” effluent.
Tertiary
treatment is the disinfection of effluent to destroy or remove pathogenic micro-organisms.
The following
table indicates the level of wastewater treatment required for the relevant
land application system:
Table 9.1:
Treatment Levels for Land Application Systems
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TREATMENT
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DEVICE TYPE
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TYPICAL LAND APPLICATION OR REUSE SYSTEM
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Primary
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· Septic Tank
· Greywater Tank
· Waterless Composting Toilet
· Wet Composting Toilet
· Combustion Toilet
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· Soil Absorption system
· Burial (compost)
· Soil Mound
· Evapotranspiration system
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Secondary (without disinfection)
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· AWTS
· Greywater Treatment
· Primary Device and Sand Filter
· Primary Device and Reed Bed
· Biological Filter System
· Membrane Reactor
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· Subsurface irrigation
· Soil Mound
· Evapotranspiration
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Tertiary (with disinfection)
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· AWTS
· Greywater Treatment
· Primary Device and Sand Filter
· Biological Filter System
· Membrane Reactor
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· Subsurface irrigation
· Soil Mound
· Evapotranspiration
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Greywater Tertiary
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· Greywater Treatment Device
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· Subsurface irrigation
· Toilet Flushing
· Washing Machine Use
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Source: Environment and Health Protection Guidelines (Modified)
9.2 TYPES OF TREATMENT SYSTEMS
1 Aerated Wastewater Treatment Systems
(AWTS)
Aerated
wastewater treatment systems provide tertiary treatment of effluent and are
accredited by NSW Department of Health. They are essentially a compact
treatment plant that processes all domestic wastewater from premises. They
contain a primary settling chamber, an aeration chamber, a clarification
chamber for the further settling of suspended solids and a chlorination chamber
for disinfection. It is a requirement of NSW Health that the systems are
inspected and serviced on a quarterly basis.
2 Biological Filter
A biological
filter system generally treats all wastes by filtration through various layers
of media. The media is inoculated with worms, beetles, mites and other soil
fauna that assist with the degradation of the waste material. For tertiary
treatment the effluent is disinfected (generally by UV light) prior to
discharge to the disposal field.
3 Composting Toilets (Wet & Dry)
Composting toilets use a process of
biological degradation by micro-organisms to convert waste material into humus.
The compost from compost/humus toilets must be removed on a regular basis and
can be disposed of on-site by burial. The design and configuration of the
systems vary significantly.
4 Grey & Black Water Split Systems
These systems provide primary treatment and
comprise of two tanks - one receiving wastewater from
the toilet, and the other receiving wastewater from the combined laundry,
shower & possibly kitchen (depending on proposed method of disposal/reuse).
Some systems included a 'grease-trap' in the plumbing between the kitchen and
the septic tank, to limit the amount of fats and oils going to the tank.
5 Greywater
Diversion/Treatment System
Greywater is wastewater from all fixtures excluding the kitchen, toilet
or urinal. Greywater “diversion devices” may be used for subsurface disposal
within the property in conjunction with an approved on-site sewage management
system. The diversion of greywater should not occur during periods of wet
weather or when illness within the premises exists. Where reuse within the home
for washing machine or the flushing of toilets is proposed a greywater
“treatment system” accredited by NSW Health is required to be installed. NSW
Health has various publications available that outline the requirements for
diversion and/or reuse.
6 Membrane Filtration
With membrane
filtration, the membrane acts as a semi-permeable filter that allows wastewater
to pass through whilst trapping bacteria, suspended particles and dissolved
solids. There are four main types of membrane filtration-reverse osmosis,
nanofiltration, ultrafiltration and microfiltration. The type of filtration
system used will depend on a number of factors including surface area,
contaminants, pH and end use.
7 Pumpout
Due to unsuitable
site conditions for wastewater disposal, Council only allows, under extreme
circumstances, the installation of pump out systems. This involves the use of a
collection well which stores treated wastewater from the septic tank. The
stored wastewater is then pumped out into approved tankers which transport the
wastewater to Council sewage treatment works where treatment and disposal
occurs
8 Reedbed Systems
Reedbed systems consist
of a primary settling unit, secondary treatment module (sub-surface flow
wetlands) and final treatment via subsurface irrigation. They treat wastewater
through settling of solids within the primary chamber. Biological and physical
filtering/treatment of the wastewater is then undertaken in the secondary
module via gravel media and selected plants which reduces the levels of
pathogens, Biological Oxygen Demand (BOD) and suspended solids. As the
wastewater flows through the media, the root system reduces the nutrient load
and uptakes moisture via transpiration. Final distribution is to an irrigation
area.
9 Sand Filters
With sand/membrane
filtration, effluent that has undergone a primary treatment is collected in a
sump or holding well and is pumped intermittently for distribution through a
bed of coarse sand. A diversion valve is placed in the return line to the sump,
and the effluent is directed to a land application system.
10 Secondary/Tertiary Treatment Systems
After the
wastewater has undergone primary treatment the effluent may be further refined
to secondary or tertiary quality. By this further process pollutant levels
within the wastewater can generally be reduced to a level that is readily
manageable. However, effluent from some treatment systems may still be
biologically active and contain high levels of pollutants. There have been many
developments in the area of ancillary on-site sewage management systems. These
systems can be added to the main treatment train with the objective of improving
the effluent quality, and so enabling the treated wastewater to be managed in a
larger number of ways. These ancillary systems are not considered to be
treatment systems requiring certification by NSW Health. At this stage they are
considered optional, but they are worthy of consideration.
11 Septic Tank
Historically,
septic tanks have been the most common method of on-site wastewater treatment
in un-sewered areas of the Shire. A septic tank provides primary treatment of
effluent and usually comprises two chambers. These chambers can be separate or
within the one tank. The first or primary chamber allows some of the solids to
settle to the bottom of the tank and oils and fats to rise to the surface to
form a scum layer. The solids that settle to the bottom of the primary chamber
undergo anaerobic decomposition forming sludge. The second chamber permits
further settling of solids and creation of a scum layer before the effluent is
discharged to a land application area (usually absorption trenches or evapotranspiration
areas).
Alternative
systems to those listed above will be considered by Council where such system
is accredited by NSW Dept Health.
9.3 DISPOSAL
Effluent that has
been treated may be discharged to a land application area. Application areas
vary in their design and method of disposal to suit a range of factors
including, type of treatment system, climatic conditions, site constraints,
etc.
Note: Conventional treatment methods
of wastewater cannot remove all bacteria or viral organisms. Exposure or
contact may result in adverse health effects and as such the surface disposal
of effluent via spray irrigation or other method is not permitted within
Nambucca Shire.
Common disposal
systems within the Nambucca Shire are:
· Absorption
Trenches and Beds
Absorption
trenches and beds are designed to dispose of treated effluent by percolation
into local soils. As absorption is the primary method of disposal this style is
ideally suited to soils with a mid range percolation rate. Soils that are too
dense will not permit the migration of the effluent leading to flooding of the
trench. Conversely soils that drain too freely (sand, gravel, etc.) may not
provide adequate filtration of the effluent and risk contamination of groundwater
supplies. Absorption trenches and beds are historically the most widely used
on-site disposal systems throughout the Shire. However, under current design
guidelines their future use will become less common due to unsuitable soil
profiles and a significant increase in the required sizing of the trench/bed to
satisfactorily accommodate the wastewater loading. The increase in the required
area is likely to result in other forms of treatment/disposal becoming more
financially viable.
· Evapotranspiration
Area
Evaporation/transpiration
areas place effluent into the root zone of plants allowing transpiration and
evaporation while sub-soil soakage is maintained. They generally have a large
surface to depth ratio in order to maximise effluent infiltration of the
vegetation root zone. Climatic conditions are a critical consideration in the
design of these systems as wet weather may have a significant adverse affect on
the efficiency of the evapotranspiration area. The sizing of the area needs to
address the infiltration of rain water and due to high seasonal rainfall of the
Nambucca Shire many consultants do not promote the use of these systems.
· Mound Disposal System (Wisconsin Mound)
Although not common within Nambucca Shire a mound system can be
considered where alternative methods are not suitable. An elevated mound is
typically a large mound of varying height made of sand or other course media. A
network of small diameter pipes with small perforations distributes the
effluent uniformly over the absorption area of the mound. The effluent
infiltrates into and percolates through the media before being absorbed into
the natural earth. The mound system is commonly used to receive wastewater from
a septic tank or secondary treatment system with its primary function as the
land application component where other types of land application are not
suitable.
· Subsurface
Irrigation
Subsurface
irrigation is generally employed with a pressurised system utilised in
conjunction with an AWTS or other secondary treatment system. The effluent is
typically disposed of via emitters in direct soil contact at depths of
150mm-350mm depending on the system design or in shallow trenches over a large
area which can incorporate gardens or the like. The pressurised system permits
even distribution of the hydraulic and nutrient load over the disposal area.
The area can be located at a higher elevation than the treatment chamber and
therefore provides more opportunities to maximise reuse.
Where any
disposal area may be subject to vehicular traffic or stock access, fencing or
other suitable barriers are to be constructed to protect the disposal area.
9.4 DESIGN
Historically, the
design and selection of on-site sewage management systems only received cursory
consideration which was reflective of the technical standards and requirements
of the time. With the release of Australian Standard 1547-1994 (subsequently
superseded in 2000) and the State Governments Environment and Health Protection
Guidelines for On-Site Sewage Management (1998) the standards of design altered
to reflect the need for specific site, soil and climatic assessment.
It is also relevant to mention that prior
to the Approvals provisions of the Local Government Act, 1993 the NSW Health
Department had responsibility for the approval of all sewage management
installations in un-sewered areas.
The primary reference documents for the
design and installation of on-site sewage management systems within Nambucca
Shire are:
1 Local Government (General) Regulation,
2005
2 AS/NZS 1547-2000 – On-site Domestic
Wastewater Management,
3 Environment and Health Protection
Guidelines – On-site Sewage Management for Single Households, and
4 Nambucca Shire Council On-site Sewage
Management Plan.
Special note should be made that only under
extreme circumstances will an on-site sewage management system be permitted
within 100 metres of a permanent waterway or environmentally sensitive area.
With such a proposal, the system must include a secondary or tertiary treatment
component and be sited to maximise any available buffer.
To assist in the preliminary investigation
of suitable on-site sewage management systems, Council has information
available for perusal relating to soil profiles and characteristics within the
Shire. Soil Landscapes of the Macksville
& Nambucca (2000) prepared by the Department of Land and Water
Conservation contains useful information to assist in the preliminary
assessment. The document is not to
be used as a substitute for site specific soil analysis as variations from the
mapping may occur resulting in an inadequate system being proposed.
New
Systems
The installation and operation of any new
on-site sewage management system requires the prior approval of Council.
An Application to Install an On-site Sewage
Management System shall include a written report detailing the type of system
proposed and a specific site and soil assessment for the subject property.
Council will assess the application for
compliance with the reference documents as listed above.
The application to install an on-site
sewage management system shall include:
1 On-site
Sewage Management Report
· The report is to be prepared by a suitably
qualified and experienced consultant,
· The report shall provide a detailed site
and soil assessment which addresses climate, topography, geology and vegetation
aspects,
· A recommendation for the most appropriate
form of on-site sewage management system,
· A recommendation for the proposed
configuration and location of the system along with supporting calculations.
2 Site
Plan
· Drawn to a scale of 1:200 or larger,
· Showing the location of the on-site system
and disposal area with distances from all buildings, property boundaries, and
any drainage lines, culverts or watercourses within 100m.
· Showing a “reserve” disposal area
equivalent in size for duplication of the disposal area (Note: the reserve area
generally applies to septic tank/absorption trench systems and may be of a
lesser size or removed completely where improved treatment/land application systems
can justify the reduction/removal),
· Indicating the position of all wastewater
drainage lines,
· Indicating the distance to any
environmentally sensitive area eg rivers, creeks, farm dams, bores, dry
gullies, etc.
3 Manufacturers
Specifications and Accreditation Certificates
· Full specifications of the proposed on-site
sewage management system,
· Certificate of Accreditation from the NSW
Department of Health.
Existing
Systems
Existing systems that are failing and
require modifications are to be upgraded to comply with the requirements for
new systems where possible. A system is considered to have “failed” when it
does not satisfactorily address the performance standards identified within
this plan.
Where compliance with the new requirements
is not possible, Council will consider alternative proposals on a case by case
basis. The protection of the environment and public health are dominant
considerations in such a circumstance.
A preliminary assessment of the site
constraints and soil condition are to be accompanied by the modified design
along with supporting calculations. The preliminary assessment may be
undertaken by persons with appropriate knowledge and experience (eg a design
consultant or suitably trained licensed plumber).
New
Subdivisions (Unsewered)
For new subdivision proposals, a land
capability assessment is required to be undertaken to demonstrate that each
proposed lot is capable of accepting the on-site disposal of wastewater. The
assessment does not need to specify the design details of each particular
system as the final design will be influenced by criteria set down by the
future home builder and such information is generally not available at
subdivision stage.
The information submitted (as a minimum)
should include:
1 Land
Capability Assessment
· The report is to be prepared by a suitably
qualified and experienced consultant,
· The report shall provide a detailed site
and soil assessment which addresses climate, topography, geology and vegetation
aspects of each lot,
· Recommendations for appropriate systems for
different landforms across the subdivision.
2 Site
Plan
· Drawn to a scale of 1:200 or other suitable
size,
· Showing the location of the effluent
disposal envelopes in relation to the building envelopes,
· Showing a “reserve” disposal area
equivalent in size for duplication of the disposal area (Note: the reserve area
generally applies to septic tank/absorption trench systems and may be of a
lesser size or removed completely where improved treatment/land application
systems can justify the reduction/removal),
· Indicating the distance to any
environmentally sensitive area eg rivers, creeks, farm dams, bores, dry
gullies, etc.
9.5 FLOOD PRONE LANDS
New
Installations:
The design and installation of new on-site
sewage management systems should ensure all components of the system are
located above the 1:100 year flood level. Where this cannot be achieved the
treatment system components are to be located above the 1:100 year flood
level/or sealed to prevent access of flood waters with the disposal area to be
assessed in accordance in the type of system proposed.
Electrical components, vents and inspection
openings of wastewater treatment devices should be sited above the 1:100 year
flood level.
Amendments/modifications
to existing systems:
Where existing systems are installed below
the 1 in 100 year flood level for a site, options to ensure the following
security of the system are to be implemented:
¨ Tanks and
collection wells are to be sealed to prevent flood water infiltrating the
system,
¨ Overflow Relief
Gullies if installed are to be terminated above the 1 in 100 year floor level,
provided this level is not above the fixture flood level or floor waste level
in the building connected to the system. See AS 3500 for details.
¨ Where flood free land is available on the site,
consideration be given to pumping liquid effluent to a disposal area above the
1 in 100 years flood level.
For land where no established flood levels
are held by Council, documented evidence is to be submitted demonstrating the
site is unaffected by flooding (eg historical information, photographs, etc).
10 MANAGEMENT
RESPONSE
10.1 RESPONSE
Applications for
installation of an on-site sewage management system were not required in rural
areas prior to the building regulations being extended to these areas from the
1 March 1982. This has resulted in a variety of standards and type of systems
for on-site sewage management being installed within the rural areas of the
shire during these unregulated years.
It is therefore
considered important that any management response to the issue of On-Site
Sewage Management systems and the disposal of waste should seek to achieve a
balance between:
a Improving
Council’s approach to achieving sustainable long term outcomes and;
b Encouraging
facility owners to upgrade these older systems to ensure that their systems are
operating and being maintained appropriately and also acknowledging the
limitation that apply to these older systems.
The situation
that exists in un-sewered areas is such that sustainable long term outcomes
should be achievable in most cases using On-Site Sewage Management Systems. In
order to achieve more sustainable and long term outcomes for on-site wastewater
management it is necessary to identify the fundamental principles which apply
to wastewater management. For the purposes of this plan the following
principles have been adopted:
1 Conservation and Re-Use of Resources
The resources in
domestic wastewater (including nutrients, organic matter and water) should be
identified and utilised as much as possible within the bounds posed by the
other performance objectives and regulatory requirements. Water conservation
practices should be encouraged and subsequent wastewater production minimised.
2 Appropriate Treatment And Disposal
The level of
wastewater treatment and the methods of disposal required depend not only on
the nature and sensitivity of the receiving environment, but also on the
potential uses of the treated wastewater and bio-solids.
3 Reliability
All on-site
sewage management systems require, to varying degrees, maintenance and
servicing to be undertaken. It is inappropriate to install a sewage management
system and to expect it to perform adequately without maintenance and
performance inspections being carried out. Education of the system user is
considered fundamental to the satisfactory performance of an on-site sewage
management system.
4 Long Term Impacts
The above principles have been used to
identify a range of goals and actions which are considered integral to
achieving more sustainable sewage management outcomes in un-sewered areas.
These goals and actions have been developed into an action plan.
5 Public Health And Health Impacts On
Occupants
Poor maintenance
of components of an on-site system can severely impact on health of the
surrounding public and that of the tenant or occupier of the premises connected
to the system. Both blackwater (toilet waste) and greywater (all other sources)
contain high bacterial loads and can be breeding grounds for insects and a
vector for disease.
10.2 ACTION PLAN
The objectives
and goals have been developed to reflect, in responding to the issue of sewage
management in un-sewered areas, a multifaceted approach which requires:
¨ Education/information.
¨ Service
provision.
¨ Efficient and
effective administration.
¨ Facility
provision.
¨ Appropriate
regulation and enforcement.
It is suggested
that if the on-site sewage management issue is viewed in this context then
regulatory and enforcement mechanisms will be minimised and generally accepted.
The regulatory
process has been developed to ensure compliance with both stages of the
approval process being Installation and Operation of the system. Aspects of
Council’s Action Plan have been included in Council’s Annual Management Plan
for quarterly reporting.
10.3 FUNDING
Council is able
to raise revenue for On-Site Sewage Management programs and services through:
¨ Ordinary rates
for general administration and services.
¨ Special rates
levied on particular parcels of land that have access to, benefit from or
contribute to the need for particular programs and services.
¨ Charges for
On-Site Sewage Management services.
¨ Approved fees for
service (including regulatory services to individuals).
¨ Develop a charge under
Section 94 of the Environmental Planning and Assessment Act.
In developing a
revenue strategy it is considered important to develop an approach which is:
¨ Administratively
efficient.
¨ Cost efficient.
¨ Fair, equitable
and minimises financial impact.
¨ Guarantees
implementation.
Having regard to
the above it is proposed that actions which involve environmental assessment,
monitoring and reporting and community education be funded through charges
levied on premises using sewage management facilities.
Provision has
been made within Council’s Management Plan for the development and ongoing
monitoring of the On-site Sewage Management Plan. The legislation requires
individual site management plans to be developed.
Accordingly
provision has been made within the management plan for annual fees and charges
to be adopted for the following activities:
¨ Approvals to
install and operate an On-Site Sewage Management System fee (one-off payment).
¨ Approval to amend
an existing on-site sewage management system.
¨ Renewal fees for
issuing an operating approval for existing systems.
¨ Pre purchase
inspection of on-site sewage management system.
¨ Registration fee
for existing systems installed prior to 1999.
¨ Issue a copy of
an operating approval.
¨ Application to
change ownership details on operating approval.
Note: Council is the only
authority who can issue approvals to operate an on-site sewage management
system under Section 68 (6) of the Local Government Act 1993.
