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5-Waters-Volume-3-Wastewater
10 Lincoln Wastewater Scheme
10.1 Scheme Summary
Estimated Population Served
| 8,373
|
Scheme Coverage (1 Jan 2021)
| Full Charges | 2,520
|
| Half Charges | 322
|
| >1 Charges | 44
|
System Components
| Piped (m) | 113,340
|
| Manholes (No.) | 947
|
| Pump Stations (No.) | 14
|
| Treatment | N/A (to Pines WWTP) |
| Disposal | N/A (to Pines WWTP)
|
| History | Original scheme installation date | 1964
|
Value ($)
| Replacement Cost | $56,108,676
|
| Depreciated Replacement Cost | $45,989,974
|
Financial
| Operator cost (scheduled and reactive maintenance) per connection
| $80.65/connection
|
Demand
(1 Jan - 31 Dec 2020)
| Annually (m3) | 711,328
|
| Average daily (m3) | 1,949
|
| Peak daily (m3) | 3,667
|
| Minimum daily (m3) | 38
|
| Infiltration | Yes
|
| Sustainability | Ultimate discharge point | To Pines WWTP Land Disposal |
10.2 Key Issues
The following key issues are associated with the Lincoln Wastewater Scheme. A list of district wide issues are located in 5Waters Activity Management Plan: Volume 1.
Table 10‑1 Lincoln Scheme Issues
| Significant infiltration and inflow is experienced during wet weather | Target renewals to address infiltration and investigate sources of infiltration |
| Meeting growth demands | Capital upgrades as required to meet growth demands |
10.3 Overview & History
In 1986 an oxidation pond with discharge to the LII River was installed with subsequent closure of the previously used Pasveer treatment plant. (Marion Place)
In early 1991 a Council Project Team recommended and received approval for the installation of aeration tanks that could be converted to a Sequential Batch Reactor (SBR) system. Three aeration tanks were installed and commissioned in 1993 but SBR's were not installed
A Council led Project Team was set up in the mid 1990's to consider the options for wastewater treatment and disposal as the consent for discharge to the Lll was due to expire.
An agreement between Selwyn District Council and Christchurch City Council was signed in November 1997 allowing pumping of treated wastewater from Lincoln Sewage Treatment Plant to Christchurch City's sewerage scheme. The permitted period of pumping was from 6pm to 4am at a maximum flow rate of 50L/sec. The maximum volume of discharge was 1,200,000m3 in each financial year. In 1998 construction of the pump station and rising main from Lincoln through to Christchurch city sewer reticulation was completed.
The growth of Prebbleton and Lincoln was limited by the discharge restrictions as defined in the CCC agreement. Without an alternative solution being adopted, no further growth could occur. Similarly for Rolleston, there would be limited growth without greater capacity of treatment and conveyance being constructed in accordance with the master plan, even on a standalone basis. Council therefore decided to investigate the options available for servicing the wider community to meet current and future needs, and subsequently formed the basis for the establishment of the Eastern Selwyn Sewerage Scheme.
From December 2012 Lincoln township wastewater treatment and disposal has been undertaken at the Pines WWTP (Rolleston) as part of the Eastern Selwyn Sewerage Scheme (refer Section 5.0). The Lincoln oxidation pond is now only used as a contingency measure in emergency situations for buffer storage.
2010/2011 Earthquakes
The 2010/2011 earthquakes had a minor impact on the scheme's below ground infrastructure. Several deep lateral connections separated but were repaired. Based on visual assessment (CCTV and qualified staff) no other damage to the below ground infrastructure or resulting effects e.g. blockages have been detected. There may however be long term but intangible impacts on maintenance and renewals programmes.
Figure 10‑2 Scheme Schematic x3
Figure 10‑3 Lincoln Master Plan
Figure 10‑4 Pump Station Failure Map
10.4 System Capacity
In recent years there has been rapid residential growth in the Lincoln community. This has placed a strain on the existing wastewater collection system. Therefore, with the implementation of the ESSS, the wastewater system has been expanded in stages to meet the increasing flows. A wastewater masterplan has been established to structure the expansion of scheme to meet the timing of new development. The capacity of existing catchment pump stations, while not yet reached, will need to be monitored and upgraded as pump renewals are considered.
Figure 10‑5 below outlines the projected population growth within Lincoln.
Figure 10‑5 Projected PE growth – Lincoln
Emergency Storage
The oxidation pond operates at a normal operating volume of 55,000m3 (7.0m). It can be raised to 7.6m or an additional 20,400m3. This would allow for 5-7 wet weather days storage from Lincoln before discharge would have to occur.
Figure 10‑6 Wet Weather Flow Capacity Map
10.5 Resource Consents
The Lincoln wastewater scheme is part of the ESSS scheme. Therefore, all wastewater is pumped to the Pines Treatment Plant located in Rolleston. The resource consents required for this treatment plant are in the ESSS section of this plan. There is a single resource consent for Lincoln, as shown in Table 10‑2.
Table 10‑2 Resource Consents
CRC145804
| To discharge to air from a sewage air valve | 21 Allendale Lane, Lincoln | 8-Apr- 14 | N/A
|
10.6 Scheme Assets
A summary of the assets within this scheme is outlined in this section.
10.6.1 Reticulation Overview
A summary of material and diameter for pipes is shown in Figure 10‑7 and Figure 10‑8.
Figure 10‑7 Pipe Material - Lincoln
Figure 10‑8 Pipe Diameter – Lincoln
10.6.2 Treatment and Disposal
Council has installed a bulk wastewater conveyance pipeline from Lincoln to the Rolleston Pines site via the Selwyn Road Pump Station (completed February 2012). This allows Prebbleton, Springston and Lincoln's sewage to be pumped to the Rolleston Pines site for treatment and disposal.
No decision has been made on relinquishing the discharge right accorded under the agreement between CCC and SDC.
Table 10‑3 Treatment and disposal facilities
Aeration Tanks (Emergency Storage) | Three aeration tanks with aerators Now used for online, peak flow lopping being directly connected to the Allendale Lane PS | 1991 |
Oxidation Pond (Emergency Storage) | Single stage pond of 3.2ha Acts as a storage buffer when inflows exceed Pines treatment capacity | 1986 |
Pump Station to CCC system (Life line) | For disposal of treated wastewater via DN250 pipeline to CCC system at Hornby. Maximum permitted discharge is 50 L/s during a daily 10 hour period between 6 pm and 4 am. The wastewater discharge standard is 50g/m3 BOD and 50g/m3 suspended solids. | 1998 |
Further reference to the treatment and disposal of Lincoln wastewater is described in Eastern Selwyn Sewerage Scheme.
10.6.3 Design
The wastewater collection system has been designed in accordance with the appropriate New Zealand engineering design guidelines at the time of construction and in accordance with the Selwyn District Council Engineering Design Standards. Specific designs for portions of the scheme outside of these standards have been considered where detailed engineering designs have been provided.
10.6.4 Pump Stations
There are currently a total of eleven pump stations, ten pump stations within the Lincoln reticulation and one pump station at the Lincoln treatment plant which has the ability to pump effluent to the Christchurch City reticulation. Details are tabled below.
Pump stations where the standby / assist pump is predicted to start have been highlighted in
yellow and
red for those that experience a peak wet weather response.
Yellow Pumps are can convey the peak flow without backing up the system
Red Pumps are unable to convey the peak flow causing the system to back up
Table 10‑4 Pump Station Overview
Lincoln (S)
Edward St PS | 1500Ø | 2 | Flygt 3127 181 MT439 | 22 | 19 | 1.5 | 3.8 | 23.1
|
Lincoln (S)
Faulks Dr PS | 2050Ø | 2 | Flygt 3171 181 SH270 | 34 | 31 | 0.2 | 0.5 | 9.3 |
Lincoln (S)
Liffey Springs PS | 2050Ø | 2 | Flygt 3153 181 HT450 | 42 | 37 | 0.6 | 1.5 | 5.9 |
Lincoln (S)
Lincolndale PS | 3500Ø | 2 | Flygt 3153 180 HT450 | 42
| 42 | 3.7 | 13.2 | 49.5
|
Lincoln (S)
LLD PS | 2550Ø | 2 | Flygt 3202 180 HT456 | 74 | 77 | 9.3 | 19.8 | 101.4
|
Lincoln (S)
Millstream Dr PS | 1800Ø | 2 | Flygt 3085 182 MT470 | 12
| 11 | 0.2 | 0.4 | 0.4 |
Lincoln (S)
Roblyn Pl PS | 1800Ø | 2 | Flygt 3102 180 MT433 | | | 0.1 | 0.4 | 2.9 |
Lincoln (S)
Ryelands PS | 1800Ø | 2 | Flygt 3085 182 HT252 | 8 | 8.7 | 1.5 | 3.3 |
12.1
|
Table 10‑5 Pump Station Storage Time Analysis
Lincoln (S)
Edward St PS | Pumps into main catchment | 4.4 | 6.8 | 550083 |
Lincoln (S)
Faulks Dr PS | Pumps directly to Allendale Lane | 145.1 | 156.6 | 622813 |
Lincoln (S)
Liffey Springs PS | Pumps directly to Allendale Lane | 52.2 | 59.3 | 620237 |
Lincoln (S)
Lincolndale PS | Pumps directly to Allendale Lane | 6.9 | 9.6 | 550863 |
Lincoln (S)
LLD PS | Pumps directly to Pines WWTP via Selwyn road | 3.2 | 4.2 | 604033 |
Lincoln (S)
Millstream Dr PS | Pumps to Edward St | 25.9 | 30.5 | 550406 |
Lincoln (S)
Roblyn Pl PS | Pumps into main catchment | 24.2 | 25.9 | 550008 |
Lincoln (S)
Ryelands PS | Pumps directly to Allendale Lane | 14.7 | 20.7 | 595957 |
The Hasendene (Murray Place) Pump Station, Barker St Pump Station, Marion Pl Pump Station have been decommissioned.
10.6.5 Rising Mains
Table 10‑6 Rising Main Overview
Lincoln (S)
Edward St PS | Lincoln | 327 | 5.2 | 1.5 | 1.0 | 0.0 | 1.0 | 45 | No data |
Lincoln (S)
Faulks Dr PS | Lincoln | 1,714 | 39.6 | 0.2 | 52.8 | 0.0 | 52.8
| 360 | No data |
Lincoln (S)
Liffey Springs PS | Lincoln | 1,134 | 32.0 | 0.6 | 15.2 | 0.0 | 15.2
| 150 | 170 - 250 |
Lincoln (S)
Lincolndale PS | Lincoln | 893 | 34.6 | 3.7 | 2.6 | 0.0 | 2.6 | 170 | 130 - 210 |
Lincoln (S)
LLD PS | Lincoln | 673
| 26.5 | 9.3 | 0.8 | 0.0 | 0.8 | 170 | No data |
Lincoln (S)
Millstream Dr PS | Lincoln | 134 | 0.7 | 0.2 | 0.1 | 0.4 | 0.5 | 10 | No data |
Lincoln (S)
Roblyn Pl PS | Lincoln | 32 | 0.3 | 0.1 | 0.5 | 0.0 | 0.5 | 30 | No data |
Lincoln (S)
Ryelands PS | Lincoln | 493 | 4.2 | 1.5 | 0.8 | 0.0 | 0.8 | 80 | No data |
10.7 Operational Management
The wastewater schemes are operated and maintained under the maintenance contract as follows:
- Contract 1241: Water Services Contract. Contract is with SICON who undertakes investigations, conditions inspections, proactive and reactive maintenance and minor asset renewals.
Wastewater sampling is completed under an agreement with Food and Health Ltd as required.
10.8 Photos of Main Assets
Photo 1 – Buffer storage tanks
| 
Photo 2 – Pond for additional buffer storage
|
Photo 3 - Ryelands Pump Station
| 
Photo 4 – LLD Pump Station
|
10.9 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 10‑7 details the risk priority rating, Table 10‑8 outlines the risks and the list of key projects is found in Table 10‑13.
Table 10‑7 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 10‑8 Risks - Lincoln
| Aeration of pond is not sufficient resulting in odour generation | install additional aerator | 2014 | 27 | 27 | 27 |
| Infiltration could overwhelm sewer pump station and ESSS network | Design high flow diversion to oxidation ponds including drawings and tender documents | 2014 | 20 | 3.5 | 3.5 |
| Infiltration could overwhelm sewer pump station and ESSS network | Allendale Lane Sewage Site - install an automate "valve" (between Allendale Lane pump station and tanks) and a larger pipe between storage tanks and pond. | 2014 | 10 | 10 | 3.5 |
| LLD sewer PS capacity is exceeded | Design additional storage for LLD sewer pump station | 2014 | 10 | 3.5 | 3.5 |
| LLD sewer PS capacity is exceeded | Upgrade LLD pump station with additional storage | 2014 | 10 | 3.5 | 3.5 |
| Safe removal of pumps | Allendale gantrey | 2017 | | 45 | 6 |
| Poor understanding of catchment flows | Roblen Pl - Flow meter | 2017 | | 9 | 2 |
| Scheme efficiency | review storeage and pump operation | 2017 | | 12 | 6 |
The list of district wide risks can be found in 5Waters Activity Management Plan: Volume 1.
10.10 Asset Valuation Details
The total replacement value of assets within the Lincoln Scheme is $56,108,676 as detailed in Table 10‑9 below.
Table 10‑9 Replacement Value, Lincoln
Plant and Equipment
| $1,491,722
|
Wastewater Reticulation
| Chamber | $294,392
|
| Lateral | $9,138,118
|
| Manhole | $4,991,806
|
| Pipe | $40,045,646
|
| Valve | $146,991
|
10.11 Renewals
The renewal profile has been taken from the 2019 5 Waters Valuation. A graph showing the renewals for this scheme are shown by Figure 10‑9 below.
Figure 10‑9 Lincoln Wastewater Renewal Profile
10.12 Critical Assets
The criticality model for Lincoln has been updated for the 2021 AcMP. The methodology of the criticality model can be found in 5Waters Activity Management Plan: Volume 1 and it provides details of how the criticality has been calculated for the reticulation assets. Table 10‑10 and Figure 10‑10 below show the calculated criticality for all of the assets within this scheme that have a recorded known length.
Table 10‑10 Length of Assets per Criticality Level
5
| Low | 57,348
|
4
| Medium-Low | 20,590
|
3
| Medium | 18,612
|
2
| Medium-High | 11,725
|
1
| High | 2,068
|
10.13 Asset Condition
The asset condition model was run for Lincoln in 2021. The methodology of the model can be found in 5Waters Activity Management Plan: Volume 1 and it provides details of how the model has been calculated for the reticulation assets (particularly pipes). Figure 10‑11 below shows the level of asset condition for all of the assets within this scheme that have a recorded known condition.
Table 10‑11 provides a description of the condition rating used within the condition model.
Table 10‑11 Asset Condition Grading
| 1.0 | Excellent |
| 2.0 | Good |
| 3.0 | Moderate |
| 4.0 | Poor |
5.0+
| Fail |
10.14 Funding Program
The 10 year budgets for Lincoln are shown by Table 10‑12. Budgets are split into expenditure, renewals, projects and capital projects. Expenditure and renewals have been reported on a district-wide basis in Volume 1.
All figures are ($) not adjusted for CPI “inflation". They are calculated on historical data, and population growth where relevant.
Table 10‑12 Lincoln Budget Summary
| 2021/2022 | -
| -
|
| 2022/2023 | -
| $100,000
|
| 2023/2024 | -
| -
|
| 2024/2025 | -
| -
|
| 2025/2026 | -
| -
|
| 2026/2027 | -
| -
|
2027/2028
| -
| -
|
2028/2029
| -
| -
|
2029/2030
| -
| -
|
2030/2031
| -
| -
|
| Total | -
| $100,000
|
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 10‑13 Key Projects
| Capital Projects | -
| Alterations to road layout for pump station
| -
| $100,000
| -
| -
| TBC
|
* LoS refers to Level of Service; 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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