Notice is hereby given that an Extraordinary Meeting of Southland District Council will be held on:




Meeting Room:



Wednesday, 31 January 2018


Council Chamber
15 Forth Street


Extraordinary Council Agenda - Late Item




Extraordinary Council

31 January 2018



ITEM                                                                                                                                                                                  PAGE


Reports - Operational Matters

A.1         Chaslands Highway Slip Repairs                                                                                                                3  


Extraordinary Council

31 January 2018


Chaslands Highway Slip Repairs

Record No:             R/18/1/1589

Author:                      Hartley Hare, Strategic Manager Transport

Approved by:         Steve Ruru, Chief Executive


  Decision                                        Recommendation                                  Information





1        The report seeks endorsement of the proposed repair works and procurement to remediate the slip that occurred on Chaslands Highway (28100 -28240) in June 2015 along with additional preventative work of a secondary site which is starting to fail/slip on Chaslands Highway (27120-27170).

Executive Summary

2        The report covers the methodology of repairing both the Major and Minor slips on Chaslands Highway from RP 28100-28240 and RP 27120-27170 respectively.

3        The main slip on the Chaslands Highway occurred in June 2015 after which a temporary bypass was established while longer term options where explored and assessed. As part of this process a work shop was held with key stakeholders which identified the key issues and potential solutions.

4        Following the workshops geotech testing was carried out to further assess / compare the geotechnical risk potentially associated with the preferred options considered.

5        From this work the option recommend is to re-establish the road on the same alignment.

6        On this basis it recommended to completed the design and proceed with the procurement of the work including award of the tender by the Chief Executive under delegation subject to formal funding approval from NZTA.



That the Council:

a)            Receives the report titled “Chaslands Highway Slip Repairs” dated 26 January 2018.


b)           Determines that this matter or decision be recognised as not significant in terms of Section 76 of the Local Government Act 2002.


c)            Determines that it has complied with the decision-making provisions of the Local Government Act 2002 to the extent necessary in relation to this decision; and in accordance with Section 79 of the Act determines that it does not require further information, further assessment of options or further analysis of costs and benefits or advantages and disadvantages prior to making a decision on this matter.


d)           Endorses the proposed methodology for repair of Chaslands Highway Slips from RP 28100-28240 and RP 27120-27170 respectively.


e)            Approves unbudgeted expenditure of up to $1.25 million to enable the Chaslands Highway slip repair works to be completed subject to NZTA confirming funding for the full cost of repairs.


f)             Endorses the procurement of lowest price conforming methodology.


g)           Delegates authority to the Chief Executive to let a contract up to the value of $1.25M subject to NZTA funding approval along with satisfactory tenders being received that provide value to the Southland District Council.




7        In June 2015 a significant slip occurred on the Chaslands Highway that resulted in the temporary closure of the road. A temporary bypass was established around the slip to reopen the road. The access is via a priority one lane.

8        Following initial investigation around the cause and options to re-establish levels of service an Investment Logic Mapping (ILM) workshop was held in May 2017. The ILM discussed and developed strategic problem/benefit statements and high level options with all affected stakeholders present (Councillors, Council staff, NZTA, Stantec, DOC and potential affected landowners).

9        At the ILM all the key issues were noted as well as opportunities of addressing the issue. The two key themes identified were around network resilience and safety. The list of options discussed were high level with consideration given to the cost versus benefit aspects of each. The preferred options considered are outlined in the Analysis section of the report below.

10      A geotech engineer was engaged to assess the terrain and material types in the area to provide a risk matrix of the preferred options. This analysis found that the risk associated with future mode failures was consistent throughout the area and hence there would be no benefit or increased surety by providing an option of a detoured route as initially considered. Because the risk is comparable it is proposed, based on cost implications, that the road be rebuilt on the existing alignment.  The method of repair is outlined below.

Proposed Repair Methodology

11      The major slip on Chaslands Highway, is to be repaired by installation of anchored post and panel retaining wall formed from Steel UC sections at 1.2m centres with two lines of soil anchors at the top, and Parallel Flange Channel (PFC) waler beams between timber backboards.

12      The total length of steel is approximately 16m, and will be formed from a 12m length and a 4m length, with a full strength bolted connection above ground.  Steel to be galvanized.  Refer to attached drawings.

13      The minor slip follows a similar repair methodology.


14      As stated above the key issues are around network resilience and safety as there are limited alternative access routes and there is an ongoing safety issue with the slip being exposed. This creates the potential of further movement occurring resulting in the remaining lane being completely lost. 

15      This road forms a key link in the area and provides the main route between Southland and Clutha District. The Chaslands Highway is part of the Southern Scenic Route and hence the decreased level of service provides a risk to a large number of visitor drivers and detracts from the driver experience.

Factors to Consider

Legal and Statutory Requirements

16      No unusual legal considerations are involved with this project.  As with all projects, but larger value projects in particular, there is the risk of a legal challenge regarding the tender results from unsuccessful tenderers.

17      To reduce this risk the Tender Evaluation Team will carefully follow the NZTA procurement procedures

Community Views

18      The key affected stakeholders were present in the discussions held at the ILM workshop in May 2017.

19      General community feedback received has been purely seeking confirmation of when the road is going to be repaired. It is clear that there is a desire for this section of road to be repaired.

Costs and Funding

20      The project cost is currently unbudgeted in the 2017/18 financial year.

21      Subject to receiving official approval the project will be 100% funded by NZTA under Special Purpose Roads.  Council’s contribution to this project will be project management.

22      The estimated project cost for the major slip is $985,735.50 which includes $120,000.00 for Investigations, Design and Management, Surveillance and Quality Assurance (MSQA) and a 20% contingency.

23      The estimated project cost for the minor slip is $165,180.00 which includes $25,000.00 for Investigations, Design and MSQA and a 20% contingency.

24      The level of competition during the tendering process will impact on the final cost.

Policy Implications

25      Council’s Procurement Policy and NZTA Procurement Strategy applies and the NZTA tender evaluation process will be followed.

26      On this basis it is proposed that this work will be procured through open tendering and awarded on a lowest price conforming basis.

27      The proposed procurement methodology has been chosen to balance minimising Professional Services inputs with obtaining competitive prices and managing risks and price certainty. The overall aim is to obtain value for money.


Options Considered

28      At the Investment Logic Mapping Workshop (ILM) several options where discussed with the three potential (preferred) options being identified:

·    Option 1: Repair Existing Road (sealed)

·    Option 2: Build Localised Detour (200m-1km)

·    Option 3: Build Bypass (i.e. through Progress Valley)

29      Numerous detours or bypasses of varying lengths were considered, but following geotechnical analysis of the surrounding area being carried out; it was deemed the risk of failure was consistent and hence no advantage in investing would be gained by a detoured route.

Analysis of Options

Option 1 – Repair Existing Road (sealed)



·        Lowest cost option

·        Preferred alignment

·        Geology assessed as similar risk to the whole surrounding area.


·        Risk of failure at adjacent sites

·        No opportunity for alignment or safety improvements.


Option 2 – Build Localised Detour (200m-1km)



·        Minimal effect on Journey time.

·        Most achievable solution short of repairing on existing alignment.

·        Cost.

·        Risk of failure at adjacent sites.

·        Legal process with land purchase.

·        Consenting requirements


Option 3 – Build Bypass (i.e. through Progress Valley)



·        Options for safety improvements on alignment.

·        Highest Cost.

·        Potentially increased Journey time.

·        Legal process with land purchase.

·        Significant consenting requirements


Assessment of Significance

30      Given that the project is classified as a special purpose road the cost of the repair works will be funded by NZTA. Staff are of the view that a decision based on this recommended option would not be significant.

Recommended Option

31      It is recommended that Council approve Option 1 – Repair Existing Road.

Next Steps

32      Obtain formal NZTA funding approval, finalise design and release for procurement.



a             Chaslands Highway Slip 1 Drawing 1

b             Chaslands Highway Slip 1 Drawing 2

c             Chaslands Highway Slip 2 Drawing 1    



31 January 2018


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31 January 2018


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31 January 2018


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