Claremont Stormwater Scheme

 

3.1       Scheme Summary

3.2       Key Issues

There are no known issues associated with the Claremont Stormwater Scheme.  A list of district wide issues are located in 5Waters Activity Management Plan: Volume 1.

3.3       Overview & History

Claremont is located on SH 1 near Templeton.  Stormwater is disposed of to roadside soakholes.  Soakholes are maintained by the Council Roading team.​

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​​ Figure 3-1
CLAREMONT Stormwater - Scheme map
Open larger map: 'Stormwater Scheme'

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Figure 3‑2 Scheme Schematic

3.4       Resource Consents

The Claremont stormwater scheme has a number of resource consents. Table 3‑1 shows the stormwater discharge permitted by the resource consents for this scheme.

Table 3‑1 Resource Consents

3.5       Integrated Stormwater Management Plan

Environment Canterbury's Land and Water Regional Plan ​became operative on the 13th December 2018.  ​​​Under policy 4.16, any reticulated stormwater system for an urban area requires a stormwater management plan. Additionally, from 1 January 2025, operators of reticulated stormwater systems will become responsible for the quality and quantity of all stormwater discharged from the reticulated stormwater system. A draft Claremont stormwater management plan is being prepared by Council. ​

A global consent has been granted for Claremont (CRC050844.1).

3.6       Scheme Assets

Council has a wide variety of stormwater assets within the district. A brief description of the assets within this scheme is provided below:

a.      Swale (Grassed) – Is a longitudinal open channel which is lined with grass.  The swale both conveys and treats stormwater.

b.      Soakholes – Are used to dispose of stormwater to ground in areas where the ground water table is low and soil permeability is high.   

A summary of material and diameter for channels and pipes is not available for this scheme.

3.7       Operational Management

The stormwater network 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.
• 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.

3.8       Photos of Main Assets

There are no photos available for this scheme.

3.9       Rapid Flood Modelling

The Council has undertaken 'Rapid Flood Hazard Assessment' modelling for its main townships.  The modelling uses DHI MIKE 21 to simulate rainfall on grid with the outputs processed through ArcGIS producing maps illustrating a range of flood deeps during different rainfall intensities and durations.

The rapid flood assessment has been generated to provide a high level summary of potential flood and ponding areas across the district during extreme rainfall events. The results from this study are not to be used to set floor levels.  The results have not been ground tested and therefore are indicative only.   

For a 50 year event, Figure 3‑3 shows the predicted flooding for Claremont.

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Figure 3‑3 Rapid Flood Modelling, Claremont

3.10       Risk Assessment

A risk assessment has been undertaken for the Claremont 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 3‑2 details the risk priority rating and Table 3‑3 outlines the risks for this scheme.

Table 3‑2 Risk Priority Rating

Table 3‑3 Risks - Claremont

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

3.11       Asset Valuation Details

The total replacement value of assets within the Castle Hill Scheme is $111,617 as detailed in Table 3-4 below. This is scheme has swales as well as soakholes (or boulder pits).

Table 3‑4 Replacement Value, Castle Hill

3.12       Renewals

The Claremont stormwater scheme consists entirely of swales, which are classified as infinite life assets. Therefore there are no renewals scheduled for this scheme. SDC undertake regular condition inspections and maintenance as required.

3.13       Critical Assets

The criticality model for Castle Hill 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 3-5 and Figure 3-4 below show​ the calculated criticality for all of the assets within this scheme that have a recorded known length.

Table 3‑5 Length of Assets per Criticality Level

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​​ Figure 3-5
CLAREMONT Stormwater - Criticality map
Open larger map: 'Stormwater Criticality'

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3.14       Asset Condition​

The asset condition model was run for Claremont in 2021. The methodology of the model can be found in 5Waters Activity Management Plan: Volume 1 and it provides details of how the model has been calculated for the reticulation assets (particularly pipes). Within this scheme there are no assets that have a recorded known condition.

3.15       Funding Program

There are no projects specific to the Claremont scheme in the 10 year LTP budgets, however the scheme will benefit from a number of district-wide initiatives. Expenditure and renewals have been reported on a district-wide basis in Volume 1. 

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.
  

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.​​​​