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Design an on-site domestic wastewater system, and describe regulatory
requirements
Level
6
Credits
16
Purpose
This unit standard is intended for people who are responsible for the design,
installation, monitoring, and regulation of on-site domestic wastewater
systems.
People credited with this unit standard are able to: determine wastewater
volumes, temporal patterns, and characteristics for on-site wastewater land
application; select the land application treatment and distribution system for
the on-site wastewater system; configure and size the land application areas
for the selected on-site wastewater treatment and land application system;
complete a report for the design, installation and commissioning, and
operation maintenance and monitoring of land application and treatment
systems; and demonstrate knowledge of regulatory requirements in relation
to the design of an on-site domestic wastewater system.
Subfield
Water Industry
Domain
Wastewater Treatment
Status
Registered
Status date
17 October 2008
Date version published
17 October 2008
Planned review date
31 December 2011
Entry information
Recommended: Unit 25127, Carry out a site and soil
evaluation for an on-site domestic wastewater system.
Accreditation
Evaluation of documentation and visit by NZQA, industry
and teaching professional in the same field from another
provider.
Standard setting body (SSB)
Primary Industry Training Organisation
Accreditation and Moderation Action Plan (AMAP) reference
0179
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
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Special notes
1
Legislation relevant to this unit standard includes but is not limited to the Resource
Management Act 1991, Building Act 2004 and relevant Building Codes, Health Act
1956, Historic Places Act 1993.
2
Rules and requirements for wastewater include but are not limited to those found in
regional and district plans, and regulatory authority requirements.
3
The standards applicable to this unit standard are:
AS/NZS 1547:2000 On-site domestic wastewater management;
AS/NZS 4360:2004 Risk Management Guidelines – Companion to AS/NZS
4360:2004;
AS/NZS 203:2004 Environmental risk management – Principles and process;
Available from http://www.standards.co.nz.
4
References
Design guidelines of territorial authorities, which include but are not limited to On-site Wastewater Systems: Design and Management Manual (Technical
Publication 58), 3rd edition (Auckland Regional Council: August 2004, available at
http://www.arc.govt.nz.
Guidelines for on-site sewage systems in the Wellington Region (WRC/RP-G-00/47),
(Greater Wellington Regional Council: February 2001), available at
http://www.gw.govt.nz.
On-site wastewater guidelines for the Manawatu-Wanganui Region (20/EXT/381),
(Horizons Manawatu: November 2000), available at http://www.horizons.govt.nz.
Guidelines for new on-site wastewater management systems (Marlborough District
Council: July 2005), available at http://marlborough.govt.nz.
RDC policy on private wastewater systems (Rodney District Council: June 2005),
available at http://www.rodney.govt.nz.
It is recommended that the assessor uses design guidelines issued by the regional or
local authorities in the candidate’s locality.
5
Assessment
Assessment against element 2 and 3 must be based on data collected from
element 1.
Assessment against element 4 must be based on the results of elements 1, 2, and 3.
6
Credit for this unit standard does not qualify the candidate to work in a drainlaying
situation that comes under the drainlayer’s licence requirements issued under the
Plumbers, Gasfitters, and Drainlayers Act 2006 and any subsequent amendments.
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Elements and performance criteria
Element 1
Determine wastewater volumes, temporal patterns, and characteristics for on-site
wastewater land application.
Performance criteria
1.1
Average, maximum, and short-term peak flows of wastewater to be managed
for the site are determined.
Range
includes but is not limited to – dwelling size, occupancy, water
supply, per capita flow allowances, water conservation measures
and/or fixtures.
1.2
Wastewater volumes and temporal patterns for an on-site wastewater design
are determined in accordance with maximum daily volume of wastewater to be
discharged.
1.3
Wastewater characteristics are determined for the site.
Range
1.4
wastewater characteristics for treatment stages – raw, primary,
secondary, advanced secondary, tertiary, reclaimed or recycled
water;
includes but is not limited to concentration of – biochemical
oxygen demand (BOD), total suspended solids (TSS), indicator
micro-organisms, nutrients, oil and grease.
Mitigating measures are identified in accordance with project constraints.
Range
dwelling size and occupancy limits, water use reduction and
recycling, increasing the level of treatment, expanding the lot area.
Element 2
Select the land application, treatment, and distribution system for the on-site wastewater
system.
Range
treatment processes may include – reduction of BOD, TSS, nutrients and
indicator micro-organisms via primary, secondary, advanced secondary, and
tertiary processes;
land application systems may include – conventional trenches, shallow and
narrow trench systems, discharge control trench systems, deep trench systems,
infiltration systems, soak pits, conventional beds, evapotranspiration beds,
mound land application systems, bottomless sand filters, primary effluent low
pressure effluent distribution (LPED), secondary effluent drip irrigation.
Performance criteria
2.1
The land application and treatment system selected is consistent with the
findings and recommendations of the site and soil evaluation report.
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2.2
The land application and treatment system selected is consistent with
responses to the site and soil constraints, environmental constraints, and site
clearances.
2.3
The loading method for gravity or pressure dose distribution is consistent with
the selected land application and treatment system.
2.4
The land application and treatment system selected is economically viable,
effective, reliable, and cost effective.
2.5
The land application and treatment system selected meets client requirements.
2.6
The land application and treatment system selected meets legislative and
compliance requirements, and contributes to sustainable environmental and
wastewater servicing outcomes.
Element 3
Configure and size the land application areas for the selected on-site wastewater
treatment and land application system.
Performance criteria
3.1
Design loading rate (DLR) and design irrigation rate (DIR) are set in accordance
with soil category determination based on site and soil characteristics.
Range
soil characteristics include – texture, structure, indicative
permeability.
3.2
The land application and reserve areas are sized and configured in accordance
with the DLR and effluent loading method.
3.3
The siting of the land application and reserve areas is consistent with
separation distances and site constraints.
3.4
The land application and reserve areas are sited to meet client requirements
without compromising set back distances and reserve areas.
3.5
The siting of the land application area enables easy access for operation and
maintenance, and is not compromised by activities on the ground surface.
3.6
The dispersal option selected is sited to optimise approved dispersal processes.
Range
approved dispersal processes – evapotranspiration, seepage,
in-soil treatment, nutrient uptake.
3.7
The land application area meets regional council compliance requirements.
3.8
The effluent distribution system is sized in accordance with the hydraulic design
requirement for gravity, siphon, or pumped pressure dosing.
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Element 4
Complete a report for the design, installation and commissioning, and operation
maintenance and monitoring of land application and treatment systems.
Performance criteria
4.1
The report provides full details of site constraints, site and soil investigation,
system selection, and design sizing.
4.2
The report provides an options assessment to determine the best practical
option including connection to reticulated sewage.
4.3
The report includes assessment of risks, impacts, and mitigation measures for
the site and surrounding environment in accordance with AS/NZS 1547:2000.
Range
soil and land stability, public health, environmental, habitat,
cultural values, natural hazards.
4.4
The installation and commissioning report provides plans and specifications for
installation and procedures for commissioning of the on-site wastewater
management system in accordance with AS/NZS 1547:2000.
4.5
The operation and maintenance report details procedures for ensuring long
term service for the installed system.
Element 5
Demonstrate knowledge of regulatory requirements in relation to the design of an on-site
domestic wastewater system.
Performance criteria
5.1
The regional and district plans are described in terms of the implications for the
design and management of an on-site domestic wastewater system.
5.2
Regional and territorial local authorities are described in terms of their role in
the approval and management of on-site domestic wastewater systems.
Please note
Providers must be accredited by NZQA, or an inter-institutional body with delegated
authority for quality assurance, before they can report credits from assessment against
unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be accredited by NZQA before they can register
credits from assessment against unit standards.
Accredited providers and Industry Training Organisations assessing against unit standards
must engage with the moderation system that applies to those standards.
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Accreditation requirements and an outline of the moderation system that applies to this
standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations
wishing to develop education and training programmes, such as minimum qualifications for
tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact the Primary Industry Training Organisation standards@primaryito.ac.nz if
you wish to suggest changes to the content of this unit standard.
 New Zealand Qualifications Authority 2016