​​18​   Raven Drive Water Supply

18.1       Scheme Summary

18.2       Key Issues

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

Table 18‑1 Raven Drive Scheme Issues

18.3       Overview & History

The Raven Drive water supply was installed in 1995, the same the year the subdivision was developed.  Council took over the operation and administration of the scheme in 1996. 

The system originally had a dionisation system with filters, a backwash reservoir and a pump.  The system was removed in March 2008 as it had not been used for a number of years and the iron levels had consistently been lower for some time.  The backwash reservoir remains but is not in use. 

Raven Drive Water Supply provides untreated groundwater to a subdivision located adjacent to Gould's Road and 1.5km east of Springston-Rolleston Road (see schematics). There are 13 sections varying from 1.5ha to 3ha and in general land is used as a “lifestyle" and not as a farm related business.

The scheme was designed and operates as an unrestricted, metered tank supply. Each property must have a storage tank (minimum of 2m³) to receive the Council water supply.  The owner is then responsible for pumping the water from the tank for property use.

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​​ Figure 18-1
RAVEN DR Water - Scheme map
Open larger map: 'Water Scheme'

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Figure 18‑2 Scheme Schematic

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18.4       System Capacity

This water supply was developed to serve the 13 lot rural residential subdivision.  All connections have been allocated and are utilised.  No additional connections are anticipated.  Existing capacity is adequate. 

Table 18‑2 Capacity Summary

​*  inferred value, ** 15 Dec 2012, *** 10 Jan 2013

18.5       Resource Consents

The Raven Drive water supply has a number of resource consents. Table 18‑3 shows the water take permitted by the resource consents for this scheme.

Table 18‑3 Resource Consents

18.6       Water Quality

The Raven Drive water supply is a secure water supply and is currently sampled weekly at the source and monthly in the reticulation.

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

Treatment

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

Zone

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

Chemical Analysis

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

Table 18‑4 Raven Drive Water Supply Raw Water Chemical Analysis Summary

18.7       Scheme Assets

A summary of material and diameter for pipes in Raven Drive is shown below by Figure 18‑3 and Figure 18‑4.

​Figure 18‑3 Pipe Material – Raven Drive

​Figure 18‑4 Pipe Diameter – Raven Drive

18.8       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.

18.9       Photos of Main Assets

​ Photo 1: Well head

​ Photo 2: Control building

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18.10       Risk Assessment

A risk assessment has been undertaken for the Raven Drive 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 18‑5​ details the risk priority rating, Table 18‑6 outlines the risks and the list of key projects is found in Table 18‑11.

Table 18‑5 Risk Priority Rating

Table 18‑6 Risks – Raven Drive

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

18.11       Asset Valuation Details

The total replacement value of assets within the Raven Drive water scheme is $347,972 with further details in Table 18‑7 below.

Table 18‑7 Replacement Value, Raven Drive

18.12       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 18‑5 below. The majority renewals occur in 2045/2046.

Figure 18‑5 Raven Drive Water Renewal Profile

18.13       Critical Assets

The criticality model for Raven Drive 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 18‑8 and Figure 18‑6 Criticality Maps below shows the calculated criticality for all of the assets within this scheme that have a recorded known length.

Table 18‑8 Length of Assets per Criticality Level

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​​ Figure 18-6
RAVEN DR Water - Criticality map
Open larger map: 'Water Criticality'

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18.14       Asset Condition

The asset condition model was run for Raven Drive 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 18‑7 below shows the level of asset condition for these assets within this scheme that have a recorded known condition.

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​​ Figure 18-7
RAVEN DR Water - Condition map
Open larger map: 'Water Condition'

Table 18‑9 provides a description of the condition rating used within the condition model.

Table 18‑9 Asset Condition Grading

The number of pipe faults is also measured through the asset management system. Figure 18‑8 shows the known historic pipe failures within this scheme.

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​​ Figure 18-8
RAVEN DR Water - Pipe Faults map
Open larger map: 'Water Pipe Faults'

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18.15       Funding Program

The 10 year budgets are shown by Table 18-10. 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 18‑10 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 18-11 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.​​​​​