This section describes the requirements for fittings that may be present in conveying a Water Supply reticulated system. These are categorised as:
- DS-7.7.1 Fire Hydrants.
- DS-7.7.2 Valves.
- DS-7.7.3 Anchor and Thrust Blocks.
- DS-7.7.4 Other Fittings (as specifically designed).
DS-7.7.1 Fire Hydrants
Drawing Ref: T714, T715, T716a, T716b, T716c, T716d, T724
Unless stated in the IDC, fire hydrants shall comply with SNZ PAS 4509. The following shall apply:
- The maximum spacing between hydrants is:
- 135m for residential areas.
- 90m for commercial and industrial areas.
- The maximum distance from a hydrant to the furthest serviceable point for fire fighting i.e. building platform is:
- 135m for residential areas.
- 90m for commercial and industrial areas. For the purposes of this requirement, a building platform means any part of a front, corner or through site and that part of a rear site which does not include the access strip. This distance shall be measured along the route which a fire hose would normally be laid after construction of the building or structure.
- In a cul-de-sac or other terminal streets, the last hydrant shall be at the end of the main at the turning head.
- If necessary, a 100mm diameter principal main shall be constructed and a hydrant placed within the privateway to satisfy the above requirements. This main will be accepted as public reticulation by Council and shall be protected by an appropriate easement to allow access for maintenance.
- Hydrants shall be readily accessible to fire appliances, generally be positioned near street intersections and not placed within 6m of any building unless authorised by the Chief Fire Officer. Attention shall be given to the location of hydrants at intersections and in cases of dispute the Council will refer the matter to the Chief Fire Officer who shall make the final decision.
- Hydrants shall not be offset into the roadway except in commercial or industrial areas where buildings can be constructed on the boundary and the offset stated in e) above applies.
- Hydrants shall be located wherever practicable within the berm but shall not be positioned within driveways or next to above ground infrastructure or trees that restrict access to or use of the hydrant.
- Additional to fire fighting requirements, hydrants shall be located:
- At high points on reticulation mains to release air during charging, allow air to enter the main when dewatering and facilitate manual release of any build up of air where automatic combination air valves are not installed.
- At localised low points on water mains to drain the water main where scour valves are not installed.
- Where a scour valve is not provided at the end of any main 100mmØ or greater.
- Drainage facilities shall be provided (or already be present) to receive the hydrant flows from dewatering and flushing operations.
- Where approved by Council, hydrants installed on trunk mains will be fitted with an isolating valve. The tee will be positioned facing horizontal.
- All fittings shall be flanged and shall be compatible with each other to achieve their intended use. Extra attention shall be given during installation to ensure that the correct tools are used and the correct tightening torque for each fitting (as advised by the manufacturer) is achieved.
- Refer to AM-7 Water Supply for approved fire hydrant components.
Drawing Ref: T717, T718, T719, T720, T721a, T721b, T721c, T721d, T722, T723, T724
The following shall apply:
- Air release valves, scour valves, pressure reducing valves and pump out branches require the specific approval of Council and shall be designed and installed in accordance with NZS 4404 Part 6.
- The maximum distance between valves on mains is:
- 500m on mains with service connections.
- 1000m on mains without service connections.
- As approved by Council where special circumstances are present.
- Wherever practicable valves shall be located in berms. For new water mains, valves shall be located at junctions with existing mains.
- Valves shall be located as close to the principal main as possible.
- Rider mains shall have valves at both ends of the rider main immediately adjacent to the principal main.
- Valve layout for intersections shall be as shown on the Standard Drawings.
- Valves shall be specifically located to minimise disruption of supply to consumers. A sufficient number of valves shall be provided to satisfy this requirement. No more than 40 independent dwelling units shall be isolated together. Isolating multiple dwelling units beyond this requires specific approval from Council.
- Butterfly valves shall not be used within the reticulation network.
These valve types can create internal obstructions that are not compatible with network operations and maintenance. They can be appropriate to achieve the design outcomes for instances such as those required for treatment plants or reservoirs.
- Pressure zone dividing valves and hydrants shall be installed as shown on the Standard Drawings.
- Additional valves may be installed to provide a secure service connection to a customer requiring a greater security of supply such as a hospital or large industrial / commercial development. The typical arrangements to facilitate partial isolation of the main while maintaining supply to the customer is shown on the Standard Drawings.
- An extension spindle shall be incorporated as necessary to ensure the top of the spindle is between 150mm and 1000mm below the finished surface level.
- All fittings shall be flanged, unless an alternative is specifically approved by Council, and shall be compatible with each other to achieve their intended use. Extra attention shall be given during installation to ensure that the correct tools are used and the correct tightening torque for each fitting (as advised by the manufacturer) is achieved.
- Refer to AM-7 Water Supply for approved valve components.
DS-7.7.3 Anchor and Thrust Blocks
Drawing Ref: T721, T722, T723
The following shall apply:
- On PVC mains: Anchor or Thrust blocks shall be provided for all bends, tees, pipe reducers, dead (blank) ends and hydrants points where an unbalanced thrust occurs on mains 50mmØ or greater as shown on standard drawing T723.
- On PE mains: It shall not be assumed that the requirement for anchor / thrust blocks on PE piped reticulation is the same as that for PVC pipe materials. For typical butt welded or electrofusion joints there is little chance of joint separation so ground support is not generally required. However, it may be necessary to provide pipe support. where:
- Change of direction is required.
- Ground conditions cannot adequately support the pipe.
- Installation is on a steep gradient. Designers shall refer to AS/NZS 2566 for clarification and shall provide detail of this within their design.
- The design of anchor or thrust blocks shall be based on the bearing value of the site’s soil conditions, using a minimum concrete strength value of 17.5 MPa concrete.
- A protective non-compressible membrane shall be provided between the pipe (irrespective of the pipe material) and the concrete anchor and thrust blocks to prevent abrasive damage to the pipe and the fitting.
- Fastening of the fitting to the Anchor or Thrust Block shall be such to allow for ease of maintenance and replacement of the fitting.
DS-7.7.4 Other Fittings
Approval is required from Council before undertaking detailed design which shall be required at the time of Development Works Approval. Where Development Works Approval is required as part of a Resource Consent, then Council approval shall be obtained at a time required by Council and before construction of the system.
Definitions in this section
Development works approval