Infrastructure Development Code

PreviousNext

City Plan Performance Standard: Appendix 12D
  1. Each water supply system shall be designed and constructed to ensure:
    1. Consistency with any relevant structure or urban growth plan;
    2. It is compatible with the design and construction of the existing water supply network. 
  2. Each water supply system shall be designed and constructed to ensure:
    1. It provides a potable water supply fit for human consumption
    2. It provides firefighting capability and coverage to the development / subdivision;
    3. All components of the water supply network shall be pre-approved by the Council and provide for an asset life that is suitable for its intended purpose; 
    4. The subdivision / development supply requirement is provided for and the adjoining network has the capacity to cater for that supply requirement and the adjoining development supply requirements. Note: Where the existing network is compromised then upgrade work to that network maybe required; 
    5. It is based on a ring main design;
    6. Gravity is used as the method for reticulation unless pump stations have been pre-approved by the Council;

Where any of the following design requirements cannot be achieved or require clarity, Council shall be contacted immediately to discuss and advise the way forward.

  1. Water Supply system designs shall:
    1. Avoid the development of pumped reticulation systems.
    2. Ensure water quality is not compromised.
    3. Ensure risks to public health and the ability to supply water for drinking and fire-fighting purposes are not introduced.
    4. Include an understanding of the implications of future land use and its design elements, such as the extent of water demand.
    5. Include an assessment of the existing reticulation and if necessary, allow for upgrading of the reticulation to cater for both the proposed and future development. This may also be varied by specific operational requirements specified by Council.
    6. Provide capacity for future development of land beyond the proposed subdivision.
    7. Be designed based on ring main design where appropriate for the consideration of future development.
  2. Water Supply system designs may:
    1. Be supplemented by the documentation noted in DS-7 Appendix A.1 General
    2. Involve the use of a computer modelling system, where approved by Council.

Detailed design shall be required at the time of Development Works Approval. Where no Development Works Approval is required, Council approval shall be obtained at a time required by Council and prior to construction of the system e.g. service connection application, building consent etc.

Councils target Asset Life is 100 years. This may not be appropriate to all network components. Refer to AM-7 Approved Materials – Water Supply for more information. 

Explanatory Note:
Asset Life is the length of time a material, product or asset can reasonably be expected to last before requiring replacement. This expectation acknowledges the combined requirement for appropriate manufacture, storage, design use, transportation, construction, installation, quality assurance, operation and maintenance of the material, product or asset.
Council typically follows industry set values for Asset Life.

DS-7.5.1   Types of Water Supply System

The main types of water supply for consumers include: 

  1. DS-7.5.1.1 Ordinary Supply Requirements e.g. Residential excluding High Density Urban. 
  2. DS-7.5.1.2 Extraordinary Supply Requirements e.g. Commercial, Industrial, High Density Urban. 
  3. DS-7.5.1.3 Fire-Fighting Supply.

Council reserves the right to specify the size of the principal and rider mains where it deems 
departure from any standard is required.

DS-7.5.1.1   Ordinary Supply Requirements

City Plan Performance Standard: Appendix 12D
  1. Each water supply system shall be designed and constructed to ensure:
    1. Peak hourly flow rates are a minimum of 0.75 litres / second / hectare.

The following shall apply:

  1. The pipe network shall be designed to provide for annual, seasonal and peak demand utilising the available pressures in the existing mains. It is the responsibility of the Designer to verify the available supply capacities to serve the proposed development.
  2. The parameters for the residential use are:
    1. Population Density:     50 people/ha.
    2. Demand:        260 litres/person/per day. 
    3. Design Peak Factor:     5 times.
    4. Consumption:     0.75 L/sec/ha (peak hourly flow).

Where the City Plan or a Resource Consent condition sets a different minimum or maximum density of lots per hectare, the design capacity shall be modified to reflect that requirement.

DS-7.5.1.2   Extraordinary Supply Requirements

City Plan Performance Standard: Appendix 12D
  1. Each water supply system shall be designed and constructed to ensure:
    1. Peak hourly flow rates are a minimum of 0.75 litres / second / hectare.

The water demand for Extraordinary Supply and / or Irrigation shall be analysed and specifically allowed for in the design. The following shall apply:

  1. Water demand shall not be less than 0.75L/sec/ha.
  2. Where the exact land use is not known at the time of design, a density flow of 0.75 L/sec/ha shall be used.

DS-7.5.1.3   Fire Fighting Supply

City Plan Performance Standard: Appendix 12D
  1. Each water supply system shall be designed and constructed to ensure:
    1. The following operating pressures are achieved:

Fire-Fighting (measured at the fire hydrant)
Maximum = 800kPa (80m) / Minimum = 100kPa (10m)

 

Explanatory Note:
The City Plan requirement of “Minimum 100kPa” refers to the residual pressure under fire flow conditions.

Unless stated otherwise in the IDC, the water supply reticulation shall comply with the requirements of the New Zealand Fire Service (NZFS) Firefighting Water Supplies Code of Practice SNZ PAS 4509.

Of particular importance are the requirements with regard to:

  1. Fire-fighting flows.
  2. Running pressure.
  3. Spacing and close proximity rules for hydrants. 
  4. Markings and indicators of hydrant location.
  5. Water storage provisions e.g. rural supply.

DS-7.5.2   Working Pressures

City Plan Performance Standard: Appendix 12D
  1. Each water supply system shall be designed and constructed to ensure:
    1. The following operating pressures are achieved:

Residential, Commercial & Industrial (measured at the Point of Supply)
Maximum = 800kPa (80m) / Minimum = 300kPa (30m)
Fire-Fighting (measured at the fire hydrant)
Maximum = 800kPa (80m) / Minimum = 100kPa (10m)

The following shall apply:

  1. Where available, Council will provide details of the pressures and flows at the point or points of connection to the existing reticulation and these shall be used for design purposes. Where this information is not available and where advised by Council, the Designer shall engage a Council approved contractor to undertake tests at the nearest hydrant(s) to the point of connection.
  2. The water supply shall be designed so that the system:
    1. Operates within the appropriate pressure range highlighted above.
    2. Is not compromised by fluctuations of pressure within the pressure range. 
    3. Ensures that during fire-fighting events, the operating pressure is maintained to achieve at least 100kPa of head at the point of supply and critical pressure point i.e. the highest hydrant in the network.
  3. Unless specified by the IDC, pipe classes shall be selected to suit the working pressure in each distribution area in accordance with Table 7.2: Pipe Classifications / Working Pressures.
  4. Council reserves the right to specify watermain materials, diameters and classifications to be used within the design where appropriate.
Explanatory Note:
This is to avoid the provision of undersized or oversized watermains when considering the whole network. When new reticulation is designed, it is typically based on the needs of a certain number of properties and the firefighting capacity required for that specific situation. Designs may need to be adjusted to consider any existing network constraints or future upstream and downstream development plans. 
Councils hydraulic model is used to ascertain the performance of the network. Pressure managed and metered areas may have an impact on what can or can’t be provided to a particular design. This in turn may affect velocity, pressure and water quality.
  1. The working pressure shall be available to consumers at the Point of Supply. 
Explanatory Note:
  1. Pressure fluctuations can occur due to the type / amount of demand put on the system as well as other contributing factors such as fire-fighting use, flushing for cleaning and maintenance, isolation for repair etc. Do not assume that Water Supply Systems work at a constant pressure at all times.
  2. Water pressure at a tap or other draw off point from within a property can be significantly different to that of the Point of Supply. Reasons for this include (but are not limited to):
    1. Height, depth or distance from the point of supply.
    2. Type and number of fittings use on the internal property reticulation.
    3. Size of the internal property reticulation. 

DS-7.5.3   Water Main Pipe Requirements

Drawing Ref: T700

City Plan Performance Standard: Appendix 12D
  1. All pipelines shall be capable of operating under the specified pressure.
  2. Mains shall have the following minimum internal diameter:
    1. Principal mains in Residential Zones and the Rural Residential Zone: 100mm
    2. Principal mains in Commercial Zones and Industrial Zones: 150mm
    3. Rider mains: 50mm

The IDC provides design, construction and quality assurance requirements for mains constructed using Polyvinyl Chloride (PVC) or Polyethylene (PE) pipe. These pipe materials do not react in the same way for all operational circumstances they are subjected to. Therefore, they are to be treated as two completely different methods that can achieve similar outcomes. 

  1. The IDC requirements are restricted to the size ranges shown in Table 7.1: Watermain Pipe Size (IDC Restriction).

Table 7.1: Watermain Pipe Size (IDC Restriction)

Main Type

(Defined Zone)

PVC PE80 PE100
Minimum Ø I.D. (mm) Maximum Ø I.D. (mm) Minimum Ø O.D. (mm) Maximum Ø O.D. (mm) Minimum Ø O.D. (mm) Maximum Ø O.D. (mm)
Principal Mains
(Residential Zone / Rural Residential Zone)
100mmØ 200mmØ 125mmØ 125mmØ 125mmØ 250mmØ
Principal Mains
(Industrial Zone / Commercial Zone)
150mmØ 200mmØ n/a n/a 180mmØ 250mmØ
Rider Mains n/a 100mmØ 63mmØ 125mmØ n/a n/a
Bulk Mains
(All Zones)
> 200mmØ I.D. (PVC) / 225mmØ O.D. (PE) Specific Design is Required 
I.D. = The Inside Diameter or Bore of the pipe       
O.D. = The Outside Diameter of the pipe 
  1. The pipe classification shall be as shown on Table 7.2: Pipe Classifications / Working Pressures.

Table 7.2: Pipe Classification / Working Pressures

Maximum Working Pressure

(kPa / Head (m))

PVC

(Open Cut)

PE80

 

PE100

 

900kPa / 90m PN9

PN12.5

SDR11

PN12.5

SDR13.6

1200kPa / 120m PN12

PN16

SDR9

PN16

SDR11

1500kPa / 150m PN15 -

PN20

SDR9

All approved pipe products and Councils target asset life are listed within AM-7 Approved Materials – Water Supply

Where your project requires reticulation pipe materials, sizes and or classifications that differ to the above, consultation (to confirm all design and acceptance criteria), specific design and approval is required from Councils Water Supply Asset Manager

Explanatory Note:
As pipe size increases, the effect of pressures and the forces they exert on the system can be different therefore, all size ranges cannot be treated the same. Council, on advice from manufacturers, have agreed that a pipe size limit is appropriate and that specific design is required for larger diameter piped reticulation or reticulation using pipe materials other than those stated within the IDC.

DS-7.5.3.1   Bulk Main Requirements

All bulk main designs require consultation to confirm all design and acceptance criteria, specific design and approval from Councils Asset Manager for Water Supply.

DS-7.5.3.2   Principal Main Requirements

Drawing Ref: T701, T706

City Plan Performance Standard: Appendix 12D
  1. Principal and rider mains shall, excluding road crossings, be located within the road zone berm and be separated from any other infrastructure or services laid parallel to it.
  2. Principal mains shall be installed as follows:
    1. Within Commercial Zones and Industrial Zones: on both sides of all roads;
    2. Within Primary Arterials, Secondary Arterials and Collector Roads: on both sides of all roads;
    3. Within Collector Roads (where development is on one side of that road only) or Local Roads: on one side of all roads.

The following shall apply:

  1. Principal mains shall be provided on both sides of the street where located on arterial roads, sub-arterial roads and / or dual carriageway streets (i.e. four lanes of traffic). 
  2. Unless approved by Council, all Principal Mains shall be located in the Road Zone.
  3. Principal mains serving industrial and commercial areas shall be laid in front of all industrial lots of the street. 
  4. The layout of mains for cul de sacs shall be as shown on standard drawing T706
  5. Table 7.3: Sizing of Principal Main shall be used as guidance for the sizing of Principal Mains (single direction feed only).

Table 7.3: Sizing of Principal Main

Diameter of Main

(mm)

Residential

Rural Residential

(If reticulation is available)

Light Industrial / Commercial High Use Industrial
PVC (I.D.) PE (O.D.)

Lots

(dwellings)

Lots

(dwellings)

Ha of development Ha of development
100mmØ 125mmØ 40 10    
150mmØ 180mmØ 160 125 23  
>200mmØ >250mmØ Specific Design

DS-7.5.3.3   Rider Main Requirements

City Plan Performance Standard: Appendix 12D

  1. Principal and rider mains shall, excluding road crossings, be located within the road zone berm and be separated from any other infrastructure or services laid parallel to it.
  2. Rider mains shall be installed as follows:
    1. Residential Zones and the Rural Residential Zone: on the side of all through roads and parts of cul-de-sacs not serviced by a principal main;
    2. Always be provided in conjunction with a principal main which has an internal diameter of ≥ 250mm diameter on the same side of the road.
    3. Be supplied from both ends (except for private ways servicing more than 6 lots)

The following shall apply:

  1. A 63mmØ PE rider main shall be provided in conjunction with a principal main where the main is 250mmØ or larger and the principal main is also defined as a bulk main.
  2. A rider main of not less than 63mmØ PE shall be laid along the road frontage of all lots not served by a principal main. 
  3. Rider mains shall be supplied from both ends, except for privateways.
  4. Rider mains may be located within privateways (right of ways) with separate service connections for each lot where the privateway (right of way) serves more than 6 residential lots. Such rider mains shall be covered by an easement in gross in favour of Council and shall allow for a flushing point and backflow prevention at the end of the line.
  5. Table 7.4: Sizing of Rider Main shall be used as guidance for the sizing of Rider Mains.

Table 7.4: Sizing of Rider Main

Diameter of Rider Main Maximum number of Residential Units (Lots)
PVC (I.D.) PE (O.D.) One End Supply Two End Supply
n/a 63mmØ 7 15
100mmØ 125mmØ 40 60

Definitions in this section

City plan

Council

Design

Designer

Development works approval

Principal

Resource consent

Road