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Questions and Answers
What is the main focus of Unit Standard 30577?
What is the main focus of Unit Standard 30577?
Installation and maintenance of stormwater handling systems.
What can people credited with Unit Standard 30578 do?
What can people credited with Unit Standard 30578 do?
What can people credited with Unit Standard 30579 do?
What can people credited with Unit Standard 30579 do?
Install and complete wingwall structures for stormwater handling systems.
What is the purpose of the Building Act 2004?
What is the purpose of the Building Act 2004?
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According to the Health and Safety at Work Act 2015, everyone in a workplace in New Zealand has the responsibility to take care of their own ______ and the safety of others.
According to the Health and Safety at Work Act 2015, everyone in a workplace in New Zealand has the responsibility to take care of their own ______ and the safety of others.
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Why does stormwater need to be managed?
Why does stormwater need to be managed?
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Only persons authorized by the Plumbers, Gasfitters, and Drainlayers Board can undertake drainlaying work.
Only persons authorized by the Plumbers, Gasfitters, and Drainlayers Board can undertake drainlaying work.
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Stormwater in New Zealand is always treated before being discharged into water bodies.
Stormwater in New Zealand is always treated before being discharged into water bodies.
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What does the Resource Management Act 1991 cover?
What does the Resource Management Act 1991 cover?
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What are some potential consequences of uncontrolled stormwater?
What are some potential consequences of uncontrolled stormwater?
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_______ systems are designed to control the flow of stormwater and prevent damage to buildings and property.
_______ systems are designed to control the flow of stormwater and prevent damage to buildings and property.
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Match the consequences with their effects on properties:
Match the consequences with their effects on properties:
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What factors should be raised with the owner or designer if they might affect the system's final performance during installation?
What factors should be raised with the owner or designer if they might affect the system's final performance during installation?
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Secondary flow paths are important to consider for positioning surface water collection systems.
Secondary flow paths are important to consider for positioning surface water collection systems.
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To perform a drain leakage test on an installed water drain, you can use:
To perform a drain leakage test on an installed water drain, you can use:
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Soak pits should be enclosed in filter cloth or geotextile materials to prevent _____ infiltration.
Soak pits should be enclosed in filter cloth or geotextile materials to prevent _____ infiltration.
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What factors are considered when sizing stormwater drainage pipes?
What factors are considered when sizing stormwater drainage pipes?
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What does a 1 in 100 year event mean in terms of probability?
What does a 1 in 100 year event mean in terms of probability?
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How can the rainfall volume to be carried to the outfall be calculated?
How can the rainfall volume to be carried to the outfall be calculated?
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A modified catchment area is calculated by multiplying the true catchment area by rainfall intensity, and then multiplying this by ____ to allow for combination of units.
A modified catchment area is calculated by multiplying the true catchment area by rainfall intensity, and then multiplying this by ____ to allow for combination of units.
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Match the following factors with their impact on stormwater systems:
Match the following factors with their impact on stormwater systems:
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What is the purpose of a retention tank?
What is the purpose of a retention tank?
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What is a detention tank used for?
What is a detention tank used for?
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Detention tanks are commonly known as rainwater tanks.
Detention tanks are commonly known as rainwater tanks.
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A retention or detention tank must be installed on a stable ___.
A retention or detention tank must be installed on a stable ___.
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Match the following components of a piped watercourse with their descriptions:
Match the following components of a piped watercourse with their descriptions:
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What is the purpose of subsoil drainage?
What is the purpose of subsoil drainage?
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What are the three main reasons for installing subsoil drains?
What are the three main reasons for installing subsoil drains?
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Clayey soils drain very easily.
Clayey soils drain very easily.
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Wingwalls in New Zealand are generally made of ______ concrete that are lifted into place.
Wingwalls in New Zealand are generally made of ______ concrete that are lifted into place.
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According to E1/AS1, how far away should access to a drain be from a building's exterior wall?
According to E1/AS1, how far away should access to a drain be from a building's exterior wall?
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Silt traps have a provision for the collection of floating material as well as silt.
Silt traps have a provision for the collection of floating material as well as silt.
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Why is it important to provide access for cleaning in drainage systems?
Why is it important to provide access for cleaning in drainage systems?
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The trench should be filled with course gravel or rock to allow __________ to pass easily into the piping system.
The trench should be filled with course gravel or rock to allow __________ to pass easily into the piping system.
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Match the sump types with their descriptions:
Match the sump types with their descriptions:
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What must be ensured for downpipes connected to retention tanks in a flooded system?
What must be ensured for downpipes connected to retention tanks in a flooded system?
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What are some common indicators of faults in stormwater handling systems?
What are some common indicators of faults in stormwater handling systems?
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Surface water collection systems require regularly removing ____, silt, and debris from channels and sumps.
Surface water collection systems require regularly removing ____, silt, and debris from channels and sumps.
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Match the following signs of faults with the appropriate drainage system indicator:
Match the following signs of faults with the appropriate drainage system indicator:
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Study Notes
Installation and Maintenance of Stormwater Handling Systems
Overview of Stormwater Handling Systems
- Stormwater is the runoff of water from urban surfaces, such as roofs and driveways, from rainfall or melting snow
- It needs to be managed to prevent flooding, erosion, and pollution of waterways
- Stormwater drains and handling systems are designed to control the flow of stormwater and prevent damage to buildings and property
Legislation, Standards, and Codes
Building Act 2004
- Provides for the regulation of building work, licensing regime for building practitioners, and performance standards for buildings
- Ensures that buildings are safe, healthy, and sustainable
Health and Safety at Work Act 2015
- Places obligations and responsibilities on everyone in a workplace to take care of their own health and safety, and the health and safety of others
- Applies to people conducting a business or undertaking, officers, workers, and visitors
Plumbers, Gasfitters, and Drainlayers Act 2006
- Ensures the competency of plumbers, gasfitters, and drainlayers to protect the health and safety of the public
- Establishes the Plumbers, Gasfitters and Drainlayers Board to regulate the industry
Plumbers, Gasfitters, and Drainlayers Regulations 2010
- Describes legal requirements and pathways to gaining registration as a drainlayer
- Sets down fees and examination details for registration
Resource Management Act 1991
- Covers sustainable management of natural and physical resources
- Ensures protection of the environment and sustainability for future generations
AS/NZS 3500.3:2015 Plumbing and Drainage – Stormwater
- Sets requirements for materials, design, installation, and testing of roof, surface, and subsoil drainage systems
- Complies with the New Zealand Building Code as an alternative solution
Stormwater Collection Systems
Surface Water Collection
- Involves collecting surface water from roofs and driveways
- Includes design, installation, and maintenance of surface water collection systems
Sizing Stormwater Drains
- Factors to consider: rainfall intensity, catchment area, runoff coefficient, and drain size
- Calculations involve determining rainfall volume, flow rate, and drain size
Installation of Surface Water Collection Systems
- Involves positioning and installing collection systems, including channels and grates, slot drains, and intake and outfall structures
- Requires testing and commissioning of systems
Intake and Outfall Structures
Intake Structures
- Involves designing and installing intake structures, including stormwater intakes and natural watercourses
- Ensures that intake structures can handle flow rates and velocities
Outfall Structures
- Involves designing and installing outfall structures, including stormwater outfalls and territorial authority stormwater systems
- Ensures that outfall structures can handle flow rates and velocities
Subsoil Drainage
Types of Soil and Subsoil Drainage
- Involves understanding types of soil and their permeability
- Includes designing and installing subsoil drainage systems, including branch subsoil drains and water tables
Design and Installation of Subsoil Drainage Systems
- Involves designing and installing subsoil drainage systems, including spacing for branch subsoil drains and diverting groundwater
Sumps and Maintenance
Types of Sumps
- Includes type-one surface water sumps and type-two sumps
- Involves understanding sump design, installation, and maintenance requirements
Maintenance of Stormwater Handling Systems
- Involves regular maintenance of surface water collection systems, sumps, subsoil drainage systems, and intake and outfall structures
- Ensures that systems are functioning as designed and do not cause pollution or damage to property### New Zealand Building Code Clause E1 Surface Water
• The primary document for installing stormwater drainage in New Zealand is the New Zealand Building Code Clause E1 Surface Water. • NZBC Clause E1 consists of three main parts: Code requirements, Verification Method E1/VM1, and Acceptable Solution E1/AS1.
Verification Method E1/VM1
• E1/VM1 describes how to determine the volume of water arriving on a building site from an upstream area. • It includes allowance for a secondary flow path and for surface water disposal to a soak pit. • Suitably qualified people (as per paragraph 1.0.7 of E1/VM1) must carry out E1/VM1 Surface Water.
Acceptable Solution E1/AS1
• E1/AS1 includes requirements for drainage materials, construction requirements, and sizing of drains, downpipes, and roof gutters. • It is limited to buildings and site work with a catchment area of no more than 0.25 hectares, and those that meet specific conditions.
Surface Water Collection Systems
• Surface water collection systems include pre-made channels and grates, kerb and channels, or half-round tiles. • These systems are intended to collect and direct surface water flow.
Surface Water Drainage
• Surface water drains are intended to carry surface water to an outfall, and are normally laid below ground level. • The design of a surface water control system must consider location, environmental requirements, permeability of surface materials, rainfall intensity, and duration.
Sizing Stormwater Drains
• Stormwater drains must be sized appropriately to handle variable flow rates. • Sizing factors include minimum drain size (85mm), catchment area, and rainfall intensity. • Drains may become pressurized during high rainfall, causing water to flow back out of sump gratings.
Storms and Drains
• E1/AS1 Surface Water requires drains to be capable of handling the rainfall from storms. • Drains must be of sufficient size and gradient to handle the rainfall from a storm with a 10% probability of occurring annually.
Rainfall Intensity
• Rainfall intensity varies across different areas of New Zealand. • A listing of rainfall intensities can be obtained from the NZBC E1 Surface Water. • Calculating rainfall volume involves multiplying the catchment area by the rainfall intensity.
Modified Catchment Areas
• The modified catchment area is a number that relates to the true catchment area and rainfall intensity. • It is calculated by multiplying the true catchment area by rainfall intensity, and then by 0.01.
Drain Size, Ground Contours, and Gradient
• When designing a surface water or stormwater system, the minimum gradients allowed should be identified. • Ground contours affect the rate of run-off of a particular collection area. • Slope corrections for run-off coefficients are used in calculations for sizing of stormwater handling systems.
Run-off Coefficients
• Run-off coefficients represent the effects of infiltration, storage, evaporation, natural retention, and interception on rainwater run-off. • They are used in the calculation of surface water run-off and assume saturated ground conditions.
Installation and Positioning
• Manufacturers provide installation requirements or guidelines, including recommended embedment and minimum cover requirements. • Surface water collection systems must be installed exactly as designed, and any departure from the approved plan leaves the drainlayer liable for any problems. • The system must be positioned with consideration for secondary flow paths to prevent flooding of buildings.### Surface Water Collection Systems
- To install a surface water collection system, excavate a trench and compact 50 mm of sand for the base.
- Lay the system according to the manufacturer's instructions, with a gradient of approximately 1:70.
- Discharge the system to a stormwater sump to collect silt and debris.
- Surround the system with concrete if it is subject to vehicle traffic.
Channel and Grate Systems
- Channel and grate systems require a concrete haunching or embedment.
- The system discharges to a yard sump, which is the demarcation point where drainlaying work begins.
Slot Drains
- A slot drain has a narrow opening at the top with slits to allow water to flow in.
- The drain then discharges into a 90 mm stormwater pipe.
- The slot drain grating may be installed level, while the drain itself can be fitted with a fall.
- Some slot drains can provide drainage at a level threshold, but must still keep external moisture out of the building.
Drain Leakage Testing
- Perform a drain leakage test on an installed water drain using a water test, low pressure air test, or high pressure air test.
- If a concrete drain is installed, it must be soaked for 24 hours prior to testing.
Intake and Outfall Structures
- Intake and outfall structures are designed to carry surface water to an appropriate outfall using gravity flow where possible.
- They must avoid the likelihood of blockages, leakage, and damage from loads or ground movements.
- Intakes can include kerb and channel sumps, silt traps, sumps, chambers, and watercourse entry wingwalls.
- Grates or grills remove floating and larger suspended solids, while traps in sumps allow for heavier materials to collect.
Stormwater Outfalls
- A stormwater outfall is the part of the drainage system that receives the water.
- Examples of outfalls include natural watercourses, soak pits, the Territorial Authority stormwater system, and the downstream side of a watercourse culvert.
- Care must be taken when discharging directly to rivers or streams to prevent pollution.
Soak Pits
- Soak pits are used to dispose of surface water by soakage.
- They require a procedure to determine the soak pit requirements for surface water disposal.
- The soakage system and any sub-surface drains need to be higher than the water table.
- A soak pit must be enclosed in filter cloth or geotextile materials to prevent soil infiltration.
Retention and Detention Tanks
- Retention and detention tanks are large-capacity underground tanks that control the flow of stormwater run-off.
- Retention tanks store stormwater for household use or for the garden during periods of water restrictions.
- Detention tanks slow the flow of stormwater to prevent overloading of the disposal system.
- Both types of tanks may be made of pre-cast reinforced concrete, corrosion-resistant metals, or high-density polyethylene.
Watercourse Drainage
- Watercourses are open drains that occur naturally as depressions in the ground.
- They may be piped to improve the surrounding land or to pass under roads.
- The secondary flow path must be allowed for when designing a building.
- Piped watercourses are the responsibility of the landowner and may require a Building Consent and a Resource Consent.
Design and Materials
- A piped watercourse has seven parts: bedding, pipe installation, intake structure, outfall structure, haunching, sub-soil drainage, and backfill and finished surface.
- The type of pipe used depends on the diameter needed, its location, and the gradient it will be laid to.
- The design of a piped watercourse is usually done by an engineer.
- The diameter of the pipe is calculated by mapping the catchment area above the drain and adding any other flows.
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Description
This quiz covers New Zealand's construction regulations, including the Building Act 2004, Health and Safety at Work Act 2015, and requirements for drainlaying work. Test your knowledge of these important laws and regulations.
