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5-Waters Volume 2 - Water Supplies
10 Hororata Water Supply
10.1 Scheme Summary
Estimated Population Served
| 920
|
Scheme Coverage (1 Jan 2021)
| Full Charges | 59
|
| Half Charges | 0 |
>1 Charges
| 47 (all restricted)
|
System Components
| Bores/Intakes (No.) | 1 Intakes (Glentunnel) |
| Treatment/Disinfection | UV and Gas Chlorination
|
| Reservoirs (No.) | Reservoir sites (2 Aitkens, 1 Harper Hills)
|
| Pump Stations (No.) | 1 Pump station |
Piped (m)
| 141,606
|
| History | Original scheme installation date | 1982 |
Value ($)
| Replacement Cost | $11,722,760
|
| Depreciated Replacement Cost | $7,432,362
|
| Financial | Operator cost (scheduled and reactive maintenance) per connection |
$563.45/connection
|
Demand (m3)
(1 Jan – 31 Dec 2020)
| Average daily
| 1,217.4
|
| Peak daily | 1,716.6
|
| Minimum daily | 55.6
|
| Average daily per connection | 4.1
|
| Type of Supply | | Restricted |
Target Pressure & Flow at boundary
| Pressure | >150 kPa |
| Flow | ±10% maric size |
| Sustainability | Well Security | Unsecure |
10.2 Key Issues
The following key issues are associated with the Hororata water supply. A list of district wide issues are located in 5Waters Activity Management Plan: Volume 1.
Table
10‑1 Hororata Scheme Issues
| Changing land use will increase and decrease demand depending on type of farming and location. The introduction of resort type accommodation will drive network water quality improvements, unless point of use treatment devices are used. | Council will monitor this and the impact of the Central Plains water scheme on dwelling and stockwater requirements. The impacts and trends will drive capital works. Council will provide upgrades where required to agreed levels of service. |
| Ensuring scheme capacity is not over allocated. | Council will ensure this supply is not over allocated which results in a decreased in level of service. |
| Complying with the amendments to Health Act requirements that will require additional treatment of water at both intakes and compliance of DWSNZ. | Council will upgrade the water supplies to meet the DWSNZ. |
| Easement/agreements to access reticulation lines necessary given changes in farm ownership and legislation. | Council will pursue easements/agreements to ensure access to reticulation mains and headworks is available. |
10.3 Overview & History
The Hororata water supply (previously part of the Selwyn Rural Water Supply) provides treated surface water to rural properties. The scheme is a restricted supply with a design of 65 L/ha/day for stock use and 2m3 for domestic use per 200 ha of a single title farm.
The scheme was installed in 1982 to replace the unreliable Snowden and Glenroy Water Race Schemes which had been in operation for over 100 years.
The original scheme did not include the Harper Hills and Hororata township areas which were added after the main system was commissioned.
There have been some minor extensions to serve small blocks on the outskirts of the original scheme boundary along with a major extension in 1999 to serve the area from Hororata Township to the Selwyn River (covering the Selwyn water race area).
A shallow well adjacent to the Selwyn River at Glentunnel supplies Hororata township and surrounding areas and Selwyn No. 2 areas UV treatment occurs at the headworks along with continual chlorination. Note that although the water source is close to Glentunnel, the Glentunnel township water is supplied from the Malvern Hills RWS – Hartleys intake.
Figure 10‑2 Scheme Schematic
10.4 System Capacity
The Hororata Water Supply provides water for stock and other on-farm purposes, as well as for residential drinking water. The town of Hororata receives water from the water supply. Water is supplied to a tank at each point of supply via a flow restrictor that limits the daily volume to an agreed allocation. Peak day demand is at the consented abstraction limit capacity. Further investigation and analysis would be required to confirm the adequacy of source and distribution capacity, and the consented take would require amendment if the scheme area were to be expanded.
Table 10‑2 System Capacity
| Abstraction Capacity | 28.3 | 2,445 | -
| Exceeds consent |
| Consented Take | 16.8 | 1,450 | 400,000 | CRC970985.1 |
| Peak Demand | 15.6 * | 1,351 | 404,906 | -
|
* 2017
10.5 Resource Consents
The Hororata water supply has resource consent. Table 10‑3 shows the water take permitted by the resource consent for this scheme.
Table 10‑3 Resource Consents
CRC970985.1
| To take groundwater at or about map reference
L35:232-468 for the purpose of providing domestic and stockwater from a piped rural water supply. | Cnr Wairiri & Homebush Roads, GLENTUNNEL | 12-Feb-10 | 11-Dec-31 | 16.8 | 1450 |
10.6 Water Quality
The Hororata water supply is non-secure.
The following details E. coli transgressions for the period 2012 to 2020.
Source
There have been 457 incidences of E. coli identified in source water during this period in the Hororata Supply, highlighting the importance of water treatment for this scheme.
Figure
10‑3 Samples with E.coli identified – source water Hororata
Treatment
There have been 9 E. coli treatment transgressions during this period for Hororata.
Figure
10‑4 E.coli Transgressions – Treatment Hororata
Zone
There have been 20 E. coli Zone transgressions during this period for Hororata.
Figure 10‑5 E. coli Transgressions -Zone
Chemical Analysis
The following is a summary of the raw water chemical analysis carried out at the Hororata Water Supply.
Table
10‑4 Hororata Water Supply Raw Water Chemical Analysis Summary
| Total Lead (g/m3) | 0.01 (Maximum Acceptable Value)
| <0.0001
| 0.00014
| 0.0006
| 0.00062
| 0.000477 | 0.000116
| 0.001097
| ✓
|
| pH (pH units) | 7-8.5 (Guideline Value)
| 7.2
| 7.4
| 7
| 7.6 | 7.3 | 7.3
| 7.6
| ✓
|
| Total Hardness (g/m3 as CaCO3) | <200 (Guideline Value)
| 32
| 37
| 37
| 41 | 41
| 35.9
| 40.6
| ✓ |
| Total Calcium (g/m3) | n/v | 9.1
| 10.6
| 10.8
| 11.8 | 12.06 | 10.49
| 11.98
| ✓ |
| 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)
| 5.2
| 5.0
| 5.0
| 5.2 | 5.4
| 5.1
| 5.45
| ✓
|
| Nitrate - Nitrogen (g/m3) | 11.3 (Maximum Acceptable Value)
| 0.54
| 0.20
| 0.13
| 0.15
| 0.14
| 0.32
| 1.0
| ✓
|
10.7 Scheme Assets
A summary of material and diameter for pipes in Hororata-Acheron is shown below in Figure 10‑6 and Figure 10‑7.
Figure
10‑6 Pipe Material – Hororata
Figure
10‑7
Pipe Diameter – Hororata
10.8 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.
10.9 Photos of Main Assets
Photo 1: Hororata Intake well
|  Photo 2: Water Treatment Plant
|
10.10
Risk Assessment
A risk assessment has been undertaken for the Hororata-Acheron 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 10‑5 outlines the risk priority rating, Table 10‑6 outlines the risks and the list of key projects is found in Table 10‑11.
The list of district wide risks can be found in 5Waters Activity Management Plan: Volume 1.
Table 10‑5 Risk Priority Rating
| > 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 10‑6 Risks – Hororata
|
Lack information about the scheme regarding turbidity |
Install a turbidity meter |
2014 |
2 |
2 |
2 |
|
Ineffective treatment |
UV and filtration upgrade |
2014 |
45 |
45 |
45 |
|
Insufficient storage capacity |
Review storage capacity |
2014 |
45 |
45 |
45 |
|
Electrical failure due to lightning or network spikes |
Install surge diverters |
2014 |
10 |
3.5 |
3.5 |
|
Failure to meet NES water meter standards |
NES Water Meter Compliance |
2014 |
20 |
6 |
6 |
|
Non-consented activities |
Renewal of consents |
2014 |
27 |
27 |
6 |
|
Protozoa compliance |
Install UV and filtration |
2017 | |
45 |
6 |
|
Inadequate capacity into the future |
storage |
2017 | |
27 |
6 |
10.11 Asset Valuation Details
The total replacement value of assets within the Hororata water scheme is
$11,722,760 with further details in Table 10‑7.
Table 10‑7 Replacement Value, Hororata
Plant and Equipment
| $1,558,273
|
|
Water Reticulation
|
| Hydrant | $9,240
|
| Lateral | $271,324
|
| Pipe | $9,510,093
|
| Supply Point | $305,645
|
| Valve | $68,186
|
10.12 Renewals
The renewal profile has been taken from the 2019 5 Waters Valuation. A graph showing the renewals for this scheme are shown by Figure 10‑8 below. There is a backlog of assets due for renewal now. The majority of renewals are due in 2049/50.
Figure
10‑8 Hororata Acheron Water Renewal Profile
10.13 Critical Assets
The criticality model for Hororata-Acheron has been updated for the 2021 AcMP. The methodology of the criticality model can be found in 5Waters Activity Management Plan: Volume 1 and it provides details of how the criticality has been calculated for the reticulation assets. Table 10‑8 and Figure 10‑9 below show the calculated criticality for all of the assets within this scheme that have a recorded known length.
Table
10‑8 Length of Assets per Criticality Level
5
| Low | 120,666
|
4
| Medium-Low | 11,684
|
3
| Medium | 882
|
2
| Medium-High | 8,477
|
1
| High | 0 |
10.14
Asset Condition
The asset condition model was run for the Hororata in 2021. The methodology of the model can be found in 5Waters Activity Management Plan: Volume 1 which provides details of how the model has been calculated for the pipe reticulation assets. Figure 10-10 below shows the level of asset condition for these assets within this scheme that have a recorded known condition.
Table 10‑9 provides a description of the condition rating used within the condition model.
Table
10‑9 Asset Condition Grading
| 1.0 | Excellent |
| 2.0 | Good |
| 3.0 | Moderate |
| 4.0 | Poor |
| 5.0+ | Fail |
The number of pipe faults is also measured through the asset management system. Figure 10‑11 shows the known historic pipe failures within this scheme.
10.15 Funding Program
The 10 year budgets are shown by Table 10‑10. Budgets are split into expenditure, renewals, projects and capital projects. Expenditure and renewals have been reported on a district-wide basis in Volume 1.
All figures are ($) not adjusted for CPI “inflation". They are calculated on historical data, and population growth where relevant.
Table 10‑10 Budget Summary
| 2021/2022 | $10,000
| $150,000
|
2022/2023
| -
| $130,000
|
2023/2024
| -
| -
|
| 2024/2025 | -
| -
|
| 2025/2026 | -
| -
|
| 2026/2027 | -
| $800,000
|
| 2027/2028 | -
| -
|
2028/2029
| -
| -
|
2029/2030
| -
| -
|
2031/2032
| -
| -
|
| Total | $10,000
| $1,080,000
|
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 10‑11 Key Projects
Capital Projects
| -
| Additional source/WTP
| -
| -
| -
| $400,000
| 100% LoS
|
Capital Projects
| -
| Reservoir at Hororata domain and pump set
| -
| -
| -
| $400,000
| 100% LoS
|
Capital Projects
| -
| Additional pressure sensors added to network
| -
| $130,000
| -
|
| 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.
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5-Waters Volume 2 - Water Supplies
