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2 Arthurs Pass Water Supply

2.1 Scheme Summary

Description		Quantity
Estimated Population Served		357
Scheme Coverage (1 Jan 2021)	Full Charges	120
	Half Charges	0
	>1 Charges	3
System Components	Bores/Intakes (No.)	1 x surface water intake
	Treatment/Disinfection	1 x water treatment plant with filtration, UV and chlorination
	Reservoirs (No.)	4 x 30m³
	Pump Stations (No.)	1
	Piped (m)	4,705
History	Original scheme installation date	1923
Value ($)	Replacement Cost	$872,883
Value ($)	Depreciated Replacement Cost	$370,365
Financial Demand (m³) (1 Jan – 31 Dec 2020)	Operator cost (scheduled and reactive maintenance) per connection	$559.56/connection
	Average daily (m³/day)	67
	Peak daily (m³/day)	129
	Minimum daily (m³/day)	11
	Average daily per connection (m³/day)	0.5
Type of Supply		High pressure and unrestricted
Target Pressure & Flow at boundary	Pressure
Target Pressure & Flow at boundary	Flow	>15 L/min
Sustainability	Well Security	Unsecure

2.2 Key Issues

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

Table 2‑1 Arthurs Pass Scheme Issues

What's the Problem

What we plan to do

High cost to carry out maintenance and operation due to isolated location and distance from the maintenance contractors base. The rating base is small and there are also limited skills available in Arthurs Pass.

Council will investigate the potential for increased remote monitoring. Council also plan to investigate optimisation of maintenance and renewals to ensure costs stay at the minimum.

The Arthurs Pass reticulation requires upgrading to comply with NZ Fire Fighting Code of Practise. For compliance this scheme would need to upgrade a number of existing water mains to 150 and 100 mm diameter and include headwork's storage.

Investigate and cost works required, including upsizing mains and sufficient storage, to ensure sufficient fire fighting flows and volumes in accordance with the NZFFCoP

This work will occur as part of the water supply treatment upgrade..

The Arthurs Pass water treatment plant requires upgrading to comply with the DWNZ.

The upgrade will address turbidity and protozoa compliance issues. It is important to deliver high quality water to Arthurs Pass as it is a popular tourist destination and risks will be managed through the Water Safety Plans. Upgrade budgeted 2017/18.

2.3 Overview & History

The original scheme was installed in 1923 by the New Zealand Railways to serve a number of railway houses. The maintenance and administration of the scheme was taken over in 1975 by the then Malvern County Council. The scheme reticulation was extended during the 1980's and an upgrade of the intake and installation of a treatment plant occurred during 1999.

The water supply intake is located in a modified pool on Avalanche Creek, sourced from an unprotected alpine catchment above the village. Water is treated (UV and filtration) but doesn't comply with DWSNZ. Fire fighting capacity is available but when operational will cause contamination of the supply. In effect bypass of the treatment system is required to allow for fire fighting flows.

There are few permanent residents in the village, with most properties occupied periodically during weekends and holidays. Several businesses serve tourists and travellers passing through the village and provide tourist accommodation and services.

The remote location and harsh alpine environment present challenges for operation and maintenance of a water supply. The village can be isolated following heavy snowfall and storm events that periodically close State Highway 73.

The community is located within the alpine fault line, and is expected to incur significant damage to its water infrastructure resulting from a 76MMI event.

Council's Supervisory Control and Data Acquisition (SCADA) system monitors the UV and cartridge filtration systems, UPS, turbidity meter, temperature gauges and flowmeter recording among other things, daily water usage, differential pressure across the filters, UV system intensity, and air and water temperatures. Alarms include low UV intensity, high turbidity, low battery, low water temperature and communications failure. The telemetry system has battery backup.

In 2020, the Arthur’s Pass Water Supply Scheme was upgraded with the addition of automatic flushing, freezing control, validated UV disinfection, chlorination, treated water storage and surface pumps.

Treatment is provided by:

Prefilter (four in parallel) with 20 micron cartridges
Cartridge filter (two in parallel) with 1 micron cartridge
UV Steriliser
Chlorination

Figure 2-1
ARTHURS PASS Water - Scheme map
Open larger map: 'Water Scheme'

Arthurs Pass - Scheme Schematic.png
Figure 2‑2 Scheme Schematic

2.4 System Capacity

There are approximately 143 sections within the Arthur's Pass Village settlement of which 14 have the potential to be further developed for residential purposes. These sections comprise of 3.3 hectares with a potential yield of 29 additional households. In addition, there are currently 18 vacant lots available in Arthur's Pass. There is significantly less developable land available within Arthur's Pass Village compared to other townships in the Malvern area. However, static projected population growth, the presence of a number of significant resource management issues and the geographic location of the settlement contained within a National Park preclude significant growth in the township.

The Arthur's Pass WTP is constrained by intake capacity.

Current demand (daily and annual volume) exceeds that permitted by resource consent.

Table 2‑2 Capacity Summary

	Flow Rate (L/s)	Daily Volume (m³)	Annual Volume (m³)	Comments
Max Intake Operating Flow	11	-	-	Stream intake, no pumping
Treatment Capacity	21.87	622	-	UV Capacity (Max flow at 90% UVT)
Consented Take	11	200	30,000*	-
Max Pump to Network Operating Flow	16.5	-	-	-
Peak Demand	8.3	260 198*	43,000****	-

* inferred value, ** 21 Jan 2015, *** 29 Jan 2015, **** 2014

2.5 Resource Consents

The Arthurs Pass water supply has a number of resource consents. Table 2‑3 shows the water take permitted by the resource consents for this scheme.

Table 2‑3 Resource Consents

Consent	Description	Location	Date Issued	Expiry Date	Consented Max Instantaneous Flow (L/s)	Consented Max Daily Volume (m³/day)
CRC991057	To take surface water, at or about map reference NZMS 260 K33:925-064, for community water supply.	Arthurs Pass Township, ARTHURS PASS	12-Aug-99	9-Feb-34	11	200

2.6 Water Quality

The Arthurs Pass water supply is a non-secure source and is currently sampled weekly for the source, treatment plant and monthly for the reticulation.

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

Source

E. coli is regularly identified in samples of the Arthur's Pass source water, highlighting the importance of treatment for this scheme. There have been 132 incidences of E. coli in source waters since 2012.

Figure 2‑3 E.coli Transgressions - Source

Treatment

There have been six E. coli treatment transgressions during this period.

Figure 2‑4 E. coli Transgressions – Treatment

Zone

There have been twelve E. coli transgressions during this period.

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Figure 2‑5 E. coli Trangressions - Zone

Chemical Analysis

The following is a summary of the raw water chemical analysis carried out at the Arthur's Pass Water Supply.

Table 2‑4 Arthur's Pass Water Supply Raw Water Chemical Analysis Summary

Parameter	Standards	2008	2011	2013	2015	2017	2018	2020	Status
Total Lead (g/m³)	0.01 (Maximum Acceptable Value)	0.00015	<0.00011	<0.00011	<0.00011	0.000267	0.000966	0.000793	✓
pH (pH units)	7-8.5 (Guideline Value)	7.1	7.6	7.3	7.8	7.4	7.7	7.9	✓
Total Hardness (g/m³ as CaCO₃)	<200 (Guideline Value)	<38	47	28	44	23.8	42.6	45.2	✓
Total Calcium (g/m³)	n/v	14	17.7	10.4	16.5	8.88	15.98	16.92	✓
Total Iron (g/m³)	<0.2 (Guideline Value)	<0.02	<0.021	<0.021	<0.021	< 0.021	<0.021	<0.021	✓
Total Sodium (g/m³)	<200 (Guideline Value)	1.8	2	1.39	2.1	1.27	1.94	2.01	✓
Nitrate - Nitrogen (g/m³)	11.3 (Maximum Acceptable Value)	0.0093	<0.05	<0.05	<0.05	< 0.05	<0.05	<0.05	✓

2.7 Scheme Assets

A summary of material and diameter for pipes in Arthurs Pass is shown below by Figure 2‑6 and Figure 2‑7.

Figure 2‑6 Pipe Material – Arthurs Pass

Figure 2‑7 Pipe Diameter – Arthurs Pass

2.8 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.

2.9 Photos of Main Assets

Photo 1: Catchment	Photo 2: Intake
Photo 3: Treatment Shed

2.10 Risk Assessment

A risk assessment has been undertaken for the Arthurs Pass 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 2‑5 outlines the risk priority rating and Table 2‑6 outlines the risks.

Table 2‑5 Risk Priority Rating

Risk Score	Level of Risk	Risk Response
> 50	Extreme	Awareness of the event to be reported to Council. Urgent action to eliminate / mitigate / manage the risk. Document risk and action in the AMP.
35-50	Very High	Risk to be eliminated / mitigated / managed through normal business planning processes with responsibility assigned.
14-35	High	Manage risk using routine procedures.
3.5-14	Moderate	Monitor the risk.
< 3.5	Low	Awareness of the event to be reported to Council. Immediate action required to eliminate / mitigate / manage the risk. Document risk and action in the AMP.

Table 2‑6 Risks – Arthurs Pass

Risk	Action/Project	Year Identified	2014 Risk Rating	2017 Risk Rating	Residual Risk Rating
Electrical failure due to lightning or network spikes	Install surge diverters	2014	6	6	6
Failure to meet NES water meter standards	NES Water Meter Compliance	2014	20	6	6
Inability to collect income from non-metered properties	Install property water meters	2014	27	27	2.1
Non-consented activities	Renewal of consents	2014	27	27	6
Frost issues	Review frost / freeze protection	2014	27	6	6
Treatment is inadequate	Review treatment and upgrade as required	2014	4	4	4
Water outages or treatment bypass when maintenance is carried out	Install reservoirs storage that could provide up to 8 hours storage to carry out maintenance without shutting off the water system. Place the reservoirs above shed or install booster pumps and you can put the reservoirs anywhere.	2014	27	27	27

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

2.11 Asset Valuation Details

The total replacement value of assets within the Arthurs Pass water scheme is $872,883 with further details in Table 2‑7 below.

Table 2‑7 Replacement Value, Arthurs Pass

Asset Class 1	Asset Class 2	Sum of Replacement Value
Plant and Equipment		$316,621
Water Reticulation	Fire	$352
	Hydrant	$32,966
	Lateral	$27,146
	Pipe	$373,540
	Supply Point	$88,310
	Valve	$33,948

2.12 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 2‑8 below. The majority of renewals occur are due now, with smaller peaks in 2024 and 2033/34.

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Figure 2‑8 Arthurs Pass Water Renewal Profile

2.13 Critical Assets

The criticality model for Arthurs Pass 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 2‑8 and Figure 2‑9 below shows the calculated criticality for all of the assets within this scheme that have a recorded known length.

Table 2‑8 Length of Assets per Criticality Level

Criticality Bands		Length (m)
5	Low	1,304
4	Medium-Low	2,033
3	Medium	555
2	Medium-High	696
1	High	0

Figure 2-9
ARTHURS PASS Water - Criticality map
Open larger map: 'Water Criticality'

2.14 Asset Condition

The asset condition model was run for Arthurs Pass 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 2‑10 below shows the level of asset condition for these assets within this scheme that have a recorded known condition.

Figure 2-10
ARTHURS PASS Water - Condition map
Open larger map: 'Water Condition'

Table 2‑9 provides a description of the condition rating used within the condition model.

Table 2‑9 Asset Condition Grading

Condition Rating	Grading
1.0	Excellent
2.0	Good
3.0	Moderate
4.0	Poor
5.0+	Fail

The number of pipe faults is also measured through the asset management system. Figure 2‑11 shows the known historic pipe failures within this scheme.

Figure 2-11
ARTHURS PASS Water - Pipe Faults map
Open larger map: 'Water Pipe Faults'

2.15 Funding Program

The 10 year budgets are shown by Table 2‑10. Budgets are split into expenditure, renewals, projects and capital projects. Expenditure and renewals have been reported on a district-wide basis in Volume 1. These can be found by following the links:

Renewal Strategy

Expenditure

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

Table 2‑10 Budget Summary

Years	Projects	Capital Projects
2021/2022	$11,000	-
2022/2023	-	$120,000
2023/2024	-	-
2024/2025	-	$300,000
2025/2026	-	-
2026/2027	-	-
2027/2028	-	-
2028/2029	-	-
2029/2030	-	-
2031/2032	-	-
Total	$11,000	$420,000

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 2‑11 Key Projects

Account Label	GL	Description	Year 1($)	Year 2($)	Year 3($)	Years 4 to 10	Funding Split *
Capital Projects	TBC	Additional pressure sensors	-	$90,000	-	-	100% LoS
Capital Projects	TBC	80/150mm raw water pipe freezing - SCADA scour automation	-	$30,000	-	-	100% LoS
Capital Projects	TBC	Second stage of Arthur's Pass School Terrace WTP upgrade	-	-	-	$300,000	100% LoS

* 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.