15   Lincoln Water Supply

15.1      Scheme Summary

15.2       Key Issues

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

Table 15‑1 Lincoln Scheme Issues​

15.3       Overview & History

The township was originally supplied water by individual bores on each property. Individual water supplies were established for the Murray Place and Cole Street (now named Millstream Drive) subdivisions in 1975/76. A community supply was installed in 1983 after nitrogen levels in the groundwater became elevated. The Murray Place bore was abandoned and the Millstream Drive bore incorporated to the new system. A new bore was drilled at Kildare Terrace utilising surface pumps to provide the bulk of the demand. By 1988 groundwater levels had dropped due to peak summer demand and the surface pumps at Kildare Terrace were replaced with a single bore pump. A third bore was drilled at West Belt in 1998 to accommodate the increasing population, and a standby generator was installed at Kildare Terrace the following year to ensure continuity of supply.

A fourth source on Eastfield Drive was drilled in 2014 and brought online in 2016 to accommodate the continued population growth. The new source consisted of a deep bore consented at 100 L/s along with the ability to automatically flush the bore during any high turbidity events. The Eastfield Drive source now serves as the main point of supply for the Lincoln Water Supply Scheme, supplying over 60% of the total volume of water consumed. 

In 2020 a fifth source, Veuve Drive, was brought online. The source consisted of a deep bore consented for 140L/s. A temporary container treatment plant was installed to allow the source to be brought online immediately and cater for the increasing summer water demand. A well at Vernon Drive has been drilled but is not yet online.​

​The Lincoln township is also home to Lincoln University, who have their own water supply and are not supplied from the Lincoln Water Supply Scheme. 

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​​ Figure 15-1
LINCOLN Water - Scheme map
Open larger map: 'Water Scheme'

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Figure 15‑2 Scheme Schematic

15.4       System Capacity

Lincoln is planned to experience significant growth over the next 30-years, which will result in a significant increase in new water connections. Figure 15‑3 shows the projected growth in water demand for Lincoln to 2051, based on the latest housing projections​.

Hydraulic models have been used to plan future water infrastructure for Lincoln, as part of a master planning exercise. The master planning provides an assessment of the sizing and timing of new infrastructure for new water sources (wells) and pipelines to service growth.  Part of the master planning requires a water balance to be developed to forecast growth, using historical peak demand per household.  The water balance forecasts the peak instantaneous flow per year versus the water resources available to determine the staging of new wells.  The well staging assumes that one well is redundant for each water supply, to take into consideration maintenance of wells, planning/timing of new wells and security of supply i.e. to maintain average/peak demand.  The master planning exercise has identified that 4 new wells be required in Lincoln, to service growth and to allow for older, less productive wells to be decomissioned (Table 15-3).​

There are no reservoirs within the Lincoln Water Supply. The use of reservoir storage in Lincoln in future may reduce the total number of wells required and/or defer the timing of new wells.

Figure 15‑3 Lincoln Water Demand

Table 15‑2 Existing Water Source Capacity 

Table 15‑3 Future Water Source Capacity​​

Figure 15‑4 Lincoln Master Plan

15.5       Resource Consents

The Lincoln water supply has a number of resource consents. Table 15‑4 shows the water take permitted by the resource consents for this scheme.

Table 15‑4 Resource Consents

15.6       Water Quality

The Lincoln water supply is fed by 5 operational wells, which are sampled twice weekly and one is sampled quarterly. The reticulation is sampled weekly. All wells except Veuve Drive are currently deemed to be secure groundwater (as at 20 July 2020). Treatment is in place at Veuve Drive (filtration and UV), but the other wells provide untreated groundwater

The following details E. coli transgressions for the period 2012 to 2020. No E. coli was identified in sampling of source water during this period.

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 Lincoln Water Supply. 

Table 15‑5 Raw Water Chemical Analysis: Eastfield Drive Well

Table 15‑6 Raw Water Chemical Analysis: Veuve Drive Well

Table 15‑7 Raw Water Chemical Analysis: Kildare Terrace Well

Table 15‑8 Raw Water Chemical Analysis: West Belt Well

15.7​​       Scheme Assets

A summary of material and diameter for pipes in Lincoln is shown by Figure 15‑5 and Figure 15‑6.

​Figure 15‑5 Pipe Material – Lincoln

Figure 15‑6 Pipe Diameter – Lincoln

​15.8       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.

15.9       Photos of Main Assets

​​ Photo 1: Lincoln Kildare Terrace plant building	Photo 2: Millstream pump shed
​​ Photo 3: West Belt bore headworks	​ Photo 4: Lincoln Eastfield Dr - Water bore, control building and flush chamber​

15.10       Risk Assessment

A risk assessment has been undertaken for the Lincoln 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 15‑9 outlines the risk priority rating, Table 15‑10 outlines the risks and the list of key projects is found in Table 15‑15.

Table 15‑9 Risk Priority Rating

Table 15‑10 Risks – Lincoln

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

15.11       Asset Valuation Details

The total replacement value of assets within the Lincoln water scheme is $13,555,301 with further details in Table 15‑11 below.

Table 15‑11 Replacement Value, Lincoln

15.12       Renewals

The renewal profile has been taken from the 2019 5 Waters Valuation. A graph showing the renewals for this scheme is shown in Figure 15‑7 below. There is a backlog of assets due for renewal now, and a further peak in renewals due in 2033/2034.​

​Figure 15‑7 Lincoln Water Renewal Profile

15.13       Critical Assets

The criticality model for Lincoln 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 15‑12 and Figure 15‑8 below shows the calculated criticality for all of the assets within this scheme that have a recorded known length.

Table 15‑12 Length of Assets per Criticality Level

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​​ Figure 15-8
LINCOLN Water - Criticality map
Open larger map: 'Water Criticality'

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15.14       Asset Condition

The asset condition model was run for Lincoln 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 15‑9 below shows the level of asset condition for these assets within this scheme that have a recorded known condition.

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​​ Figure 15-9
LINCOLN Water - Condition map
Open larger map: 'Water Condition'

​Table 15‑13 provides a description of the condition rating used within the condition model.

Table 15‑13 Asset Condition Grading

The number of pipe faults is also measured through the asset management system. Figure 15‑10 shows the known historic pipe failures within this scheme.

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​​ Figure 15-10
LINCOLN Water - Pipe Faults map
Open larger map: 'Water Pipe Faults'

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15.15       Funding Program

The 10 year budgets for Lincoln are shown by Table 15‑14. Budgets 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 15‑14 Lincoln 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.
  

There are several major projects for Lincoln water scheme in the LTP budget. 

Table 15​‑15 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. ​