​​17​   Rakaia Huts Water Supply

17.1       Scheme Summary

17.2       Key Issues

The following key issues are associated with the Rakaia Huts water supply.  A list of district wide issues are located in 5Waters Activity Management Plan: Volume 1.

Table 17‑1 Rakaia Huts Scheme Issues

17.3       Overview & History

The Rakaia Huts Water Supply provides treated groundwater to the Rakaia Huts community on the eastern bank at the mouth of the Rakaia River. Water for the Rakaia Huts water supply is obtained from a single shallow bore on Pacific Drive and treated at a single WTP. A single bore pump delivers water through the water treatment plant (WTP) where it is filtered and UV treated prior to being stored in two 30m³ reservoirs. The water is then boosted through two surface pumps to the reticulation. The scheme was designed as a high pressure, unrestricted metered supply. The majority of Rakaia Huts Water Supply Scheme is made up of residential connections (occupied and semi-occupied dwellings), along with a camping ground and public recreation area. Four backflow prevention devices are present within the scheme, including at the camp ground.

The booster pumps are controlled by a pressure sensor. When the pressure drops then either one or both of the smaller booster pumps start. If the pressure continues to drop, the larger fixed speed booster pumps is called to run. The smaller booster pumps continue to run. If the reservoir level becomes low, the bore pump is started, refilling the reservoir. The control system is linked to the Council’s Supervisory Control and Data Acquisition (SCADA) system and all inputs are powered by mains electricity. The SCADA system monitors the pumps, inflow into the reticulation, and reservoir level, recording among other things, daily water usage and pump hours. Alarms include pump fault and communications failure. The telemetry system has battery backup. A Backup generator is permanently on site in the event of power failure.

A piped water supply was orginally requested for the township by the North Canterbury Catchment Board (now Environment Canterbury) in 1986, as the Board has stated that it was unlikely to grant water right applications for septic tank effluent without a reticulated community supply.  Households at that time obtained their water from shallow wells that were contaminated. The scheme was designed as an unrestricted supply with a low level of compliance with the NZ Fire Fighting Code of Practice and installed during 1989. In 2007/08 land transfers between Council and residents occurred to reflect actual property/reserve boundaries. 

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​​ Figure 17-1
RAKAIA HUTS Water - Scheme map
Open larger map: 'Water Scheme'

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Figure 17‑2 Scheme Schematic

​​17.4       System Capacity

This water supply was developed with sufficient capacity to serve the subdivision. All connections have been allocated and are utilised. Most allocated connections are utilised and it is not intended that this supply area be extended. Existing capacity is adequate. 

Table 17‑2 Capacity Summary

​*  inferred value, ** Feb 2015​

17.5       Resource Consents

The Rakaia Huts water supply has a number of resource consents. Table 17‑3 shows the water take permitted by the resource consents for this scheme.

Table 17‑3    Resource Consents

17.6       Water Quality

The Rakaia Huts water supply is a secure supply which is sampled quarterly at the treatment plant plant and reticulation point.

The following details E. coli transgressions for the period 2012 to 2020. 

Source

There have been no E. coli source transgressions during this period. 

Treatment

There have been no E. coli treatment transgressions during this period. 

​Zone

There have been no E. coli Zone transgressions during this period.

Chemical Analysis

The following is a summary of the raw water chemical analysis carried out at the Rakaia Huts Water Supply. 

Table 17‑4 Rakaia Huts Water Supply Raw Water Chemical Analysis Summary

17.7       Scheme Assets

A summary of material and diameter for pipes in Rakaia Huts is shown below in Figure 17‑3 and Figure 17‑4.

​Figure 17‑3 Pipe Material – Rakaia Huts

​Figure 17‑4 Pipe Diameter – Rakaia Huts

17.8       Operational Management

The water supply is operated and maintained under two maintenance contracts as follows:

• Contract 1241: Water Services Contract. Contract is with SICON who undertakes investigations, conditions inspections, proactive and reactive maintenance and minor asset renewals; and
• Contract 1202: Parks and Reserves Contract. Contract is with SICON who undertakes the maintenance of land scape features related to water services e.g. mowing, gardens etc.

Water quality sampling is completed under an agreement with Food and Health Ltd as required.​

17.9       Photos of Main Assets

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Photo 1: Source well and reservoir

Photo 2: Water Treatment Plant

17.10       Risk Assessment

A risk assessment has been undertaken for the Rakaia Huts scheme. The key output from the risk assessment is the identification of any extreme and high risks which need to be mitigated. In order to mitigate these risks they have been included and budgeted for in the projects within this LTP. Table 17‑5 details the risk priority rating, Table 17‑6 outlines the risks and the list of key projects is found in Table 17‑11.

Table 17‑5 Risk Priority Rating

Table 17‑6 Risks – Rakaia Huts

The list of district wide risks can be found in 5Waters Activity Management Plan: Volume 1.

17.11       Asset Valuation Details

The total replacement value of assets within the Rakaia Huts water scheme is $563,424 with further details in Table 17‑7 below.

Table 17‑7 Replacement Value, Rakaia Huts

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17.12       Renewals

The renewal profile has been taken from the 2019 5 Waters Valuation. A graph showing the renewals for this scheme are shown by Figure 17‑5 below. The majority of renewals are due now, with further peaks in 2033 and 2036. 

​Figure 17‑5 Rakaia Huts Water Renewal Profile

17.13       Critical Assets

The criticality model for Rakaia Huts has been updated for the 2021 AcMP. The methodology of the criticality model can be found in 5Waters Activity Management Plan: Volume 1 and it provides details of how the criticality has been calculated for the reticulation assets. Table 17‑8 and Figure 17‑6 below shows the calculated criticality for all of the assets within this scheme that have a recorded known length.

Table 17‑8 Length of Assets per Criticality Level

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​​ Figure 17-6
RAKAIA HUTS Water - Criticality map
Open larger map: 'Water Criticality'

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17.14       Asset Condition

The asset condition model was run for Rakaia Huts in 2021. The methodology of the model can be found in 5Waters Activity Management Plan: Volume 1 which provides details of how the model has been calculated for the pipe reticulation assets. Figure 17‑7 below shows the level of asset condition for these assets within this scheme that have a recorded known condition.

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​​ Figure 17-7
RAKAIA HUTS Water - Condition map
Open larger map: 'Water Condition'

Table 17‑9 provides a description of the condition rating used within the condition model.

Table 17‑9 Asset Condition Grading

The number of pipe faults is also measured through the asset management system. Figure 17‑8 shows the known historic pipe failures within this scheme.

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​​ Figure 17-8
RAKAIA HUTS Water - Pipe Faults map
Open larger map: 'Water Pipe Faults'

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17.15       Funding Program

The 10 year budgets are shown by Table 17-10. Bu​dgets are split into expenditure, renewals, projects and capital projects. Expenditure and renewals have been reported on a district-wide basis in Volume 1. 

All figures are ($) not adjusted for CPI “inflation".  They are calculated on historical data, and population growth where relevant.​

Table 17-10 Budget Summary

​An explanation of the categories within the budgets are as follows below:

• Expenditure consists of operation and maintenance costs;
  
• Renewals are replacement of assets which are nearing or exceeded their useful life;
• Projects are investigations, decisions and planning activities which exclude capital works; and
• Capital projects are activities involving physical works.
  

​Table 17-11 Key Projects​

​ * Where LoS refers to Level of Service and G refers to Growth

The list of district wide projects can be found in 5Waters Activity Management Plan: Volume 1.

Discussion on Projects

Projects​​​ have been determined based on their:

• Relevance to the scheme
• Requirement to be completed under legislation
  
• Ability to bring the scheme up to or maintain the Level of Service required under council's Asset Management Policy. 

Many projects are jointly funded by more than one scheme and activity.  Each scheme pays a pro-rata share only, equivalent to the number of connections.

Discussion on Capital and Projects

Where relevant, Capital (Levels of Service) and Capital (Growth) projects have been included in the scheme financial details. 

Levels of Service Projects and growth splits have been provided to ensure the costs of population driven works are clear.​​​​