Kate Valley Landfill
Peer Review Panel
Annual Report Number 7
Covering the period July 2010 to March 2012
May 2012
Members of the Panel:
Mark Milke, Canterprise Limited, University of Canterbury, Private Bag 4800, Christchurch. Ph: 03 364 2248; mark.milke@canterbury.ac.nz
Bruce Riddolls, Riddolls Consultants Ltd, PO Box 2854, Christchurch 8140. Ph: 03 337 0417; riddolls@vodafone.co.nz
CONTENTS
CONTENTS ................................................................................................................. 1
1. Objective of Report ............................................................................................. 2
2. Background .......................................................................................................... 2
3. Scope of Review .................................................................................................. 2
4. Membership of Panel .......................................................................................... 3
5. Landfill Design, Construction, and Management (General Consent
Condition 12) ............................................................................................................... 3
5.1 Design and Construction ............................................................................... 4
5.2 Management and Monitoring Plans............................................................. 5
5.3 Water Control, including Groundwater, Stormwater and Leachate
Management ............................................................................................................ 5
5.4 Landfill Gas ...................................................................................................... 7
5.5 Compaction, including Method and Degree .............................................. 7
5.6 Waste Acceptance ........................................................................................... 7
5.7 Cover Materials .............................................................................................. 8
5.8 Monitoring, Modelling and Records ............................................................ 8
5.9 Rehabilitation ................................................................................................... 9
6. Managing Hydration Level of GCL: (Condition 22, CRC021914)…………9
7. Water Supply and Silt Dams (Condition 14, CRC 021919) ......................... 10
8. Sedimentation Dam Slope Stability (Condition 13, CRC 021919) .............. 10
9. Stability of Northern Access Road (Condition 48, RC 020069) .................. 10
10. References .......................................................................................................... 11
Appendix 1
Consent Conditions Relevant to PRP
Appendix 2
Dates of PRP meeting and site visits
1. Objective of Report
The objective of the Annual Report is to meet the obligations of General Consent
Conditions 12 and 13 (Appendix 1).
2. Background
The Canterbury Regional Landfill at Kate Valley is owned by Transwaste Canterbury
Ltd (TCL), a public – private partnership between five Canterbury councils and
Canterbury Waste Services Ltd. (CWS). The development and operation of the
landfill is being undertaken by CWS.
Geotech Consulting Ltd has been responsible for the geological site investigations for
the project. This has included the subsurface drilling and soil testing prior to detailed
design, providing advice to the geotechnical designers, and mapping of the subgrade
during construction.
Tonkin & Taylor Ltd (T&T) have been the principal designers of the landfill and
associated structures. They have been involved in the preliminary planning of the
landfill, undertaken the detailed geotechnical design, and overviewed the
construction of the landfill. They also provided quality assurance services, including
a full time technician, during the initial construction phase. Subsequently T&T have
overviewed the work of the technician employed by CWS and provided a technician
during the liner construction work of each phase.
The initial construction of the landfill was undertaken under an Alliance Contract
between CWS and Fulton Hogan Ltd. The Alliance engaged subcontractors to carry
out some of the construction work. While T & T were not formally part of the alliance
they worked very closely with the contractors and provided quality assurance and
testing services during the construction.
The Peer Review Panel (PRP) has been established by TCL in accordance with
General Consent Condition 11 (Appendix 1). The condition provides for the
establishment of a Peer Review Panel to review the design, construction, operation,
and after-care of the landfill, and to assess whether or not the work is undertaken by
appropriately qualified personnel in accordance with good practice.
3. Scope of Review
The role of the PRP has been defined as one of independent technical and specialist
review. It has not been involved in design checks, oversight of construction, or
checking compliance with consent conditions (which is the responsibility of the
relevant councils).
2
The timeframe for this review is 1 July 2010 to 1 March 2012. The timeframe is
greater than a year to acknowledge that the PRP’s involvement is ongoing, and the
review of operations since 1 July 2011 has continued. In some cases, the lack of
documentation means that a complete review of activities since 1 July 2011 is not
possible. This timeframe implies that the time between 1 July 2011 and the release of
the PRP report will be under consideration in two annual reports.
During this time, the PRP has been kept fully informed on the design, construction,
and operation of the project by way of (1) meetings convened by CWS or the PRP, (2)
provision of draft or final reports by CWS, (3) direct consultation with relevant
personnel, and (4) site visits. This process has been applied to all the key elements of
the project. The PRP has been provided with every opportunity to communicate its
views to CWS and its technical advisors, and to receive feedback. Dates for meetings
and site visits attended by the PRP are provided in Appendix 2. Key documents
provided to the PRP and considered relevant to consent monitoring officers are listed
in the References section of this report.
This review includes consideration of the draft 2011 Landfill Annual Report. A draft
report is used for peer review and for review by the relevant councils, and the final
report will be issued after completion of this review and those of the councils.
4. Membership of Panel
Dr Mark Milke, Canterprise Ltd., environmental engineering reviewer and Dr Bruce
Riddolls, Riddolls Consultants Ltd, engineering geology reviewer, with specialist
input from Dr Trevor Matuschka*, Engineering Geology Ltd, landfill engineering
reviewer and Mr Tony Pickford†, dam engineering reviewer
5. Landfill Design, Construction, and Management (General
Consent Condition 12)
The Peer Review Panel believes the Landfill work is being undertaken by
appropriately qualified personnel. The overall assessment is that the Landfill work is
in accordance with good practice. Some aspects of the work are below what we
would consider the level of good practice, but many are above that standard.
The PRP understands that TCL has not found evidence of significant adverse effects
on the facilities as a result of the Canterbury earthquake sequence that began on 4
September 2010. A magnitude Mw7.1 earthquake located approximately 73km
south-west of the site occurred on 4 September 2010. The resulting ground motions
were strongly felt at the site. The only damage was a small rockfall which covered
*
Specialist member with expertise in landfill construction appointed under the provision in General
Consent Condition 13.
†
Specialist member with expertise in dams appointed under the provision in General Consent
Condition 13.
3
about half the road in one location, which was quickly removed. The peak ground
acceleration is estimated to have been between about 0.07-0.15g. Another large
earthquake (magnitude Mw6.3) occurred on 22 February 2011 approximately 50km
south of the site at Christchurch resulting in 180 deaths and major damage to central
Christchurch. While it was felt at the site, ground motion was not as strong as the
September 2010 earthquake and no damage resulted. These events are well below
the design level earthquake peak ground accelerations (0.5g for DBE and 0.7g for
MCE).
Although no significant effects have been seen, it would be appropriate to conduct
further investigation into the potential impacts of heightened earthquake activity,
and for that investigation to be subject to review by the PRP.
5.1
Design and Construction
The design of the landfill has been undertaken by T&T. The design includes the
under drainage system, earthworks (foundation preparation, liner earthworks, toe
bund), liner systems, leachate collection system, perimeter landfill road and
stormwater drainage. Some amendments to design details have been made by CWS
as a result of operating experience and observations.
During the period covered by this report the following design activities were
undertaken and reported:





Concept Drawings, for next 5 years of land fill life were updated and they are
included in Appendix A of the TCL Annual Report8
Modifications to capping design
Sub-cap drainage system to prevent leachate breakout
Design of Phase 2B
Investigation into on-site leachate treatment
Modifications to the capping design were made to ensure it functions to limit rainfall
infiltration and to contain gas. The design involved thickening daily and
intermediate cover and the use of material with a lower permeability for
intermediate cover. A leachate drainage system, located immediately below the
landfill cap, has been designed and is being implemented. It consists of subsurface
drains running down the slope, located at 50m centres. Where potential exists for
leachate breakouts, or where actual leachate breakouts occur, they can be drained to
the subsurface drains. The design changes have been reviewed and approved by the
PRP. The Phase 2A Design Report 14 was reissued in September 2011 and the Phase
1A-3 Design Report 17 issued in October 2011 CWS provided a draft Design Report 26
and Drawings27 for Phase 2B in March 2012.
Design by T&T is considered to represent best practice and documentation of the
design is very good.
The principal construction activity in 2010/2011 was the completion of construction
of Phase 1A-3, including placement of 3,600m2 of liner and liner protection and
4
capping of Phases 1A, 1A-3 and 2A. Excavation in the Phase 4A area was
undertaken, primarily to provide fill for construction. In addition, some
improvements were made to the roads and signage on the Facilities Platform to
improve the safety of traffic movements in this area.
Construction of Phase 1A-3 was undertaken with a combination of CWS and hired
plant. CWS staff supervises construction, and also undertake material testing and
construction quality assurance (QA) under the direction of T&T who also undertake
regular site visits to observe construction and have their own technician on site fulltime during liner construction and other critical stages. The level of supervision and
QA is appropriate. CWS have produced Construction Reports for Phase 2A-116 and
Phase 1A-319. Appendices for the Phase 2C Construction Report24 were also
provided.
Operation of the landfill involves placement of a temporary cap. CWS have
modified the design of the cap to ensure that it functions effectively to prevent
leachate breakouts and to contain landfill gas. Daily cover has been increased to
0.3m thick and intermediate cover has been increased to 500mm and for final
external surfaces is now constructed from regolith material which is stockpiled on
site. This material is not suitable for Type 1A or Type 1B, but is very good for
intermediate cover. Phases 1A, 1A-3 and 2A were retrospectively capped to the new
design in the period covered by this report. This modification was made to reduce
rainfall infiltration and the quantity of leachate produced and to restrict release of
landfill gas, and is endorsed by the PRP.
On the basis of the information provided and inspection of the works during
construction, the PRP is satisfied that the design and construction of the various
elements of the landfill undertaken in the reporting period satisfies the requirements
of the Resource Consent conditions, complies with other statutory requirements and
is in accordance with current landfill design practice.
5.2
Management and Monitoring Plans
The TCL Landfill Annual Report8 is a clear, complete, and comprehensive review of
the landfill’s activities, and presents excellent practice in terms of the reporting
associated with landfill management and monitoring. The Landfill Management
Plan (LMP) has been recently updated. In June/July of 2012, the PRP will participate
in revision of the document.
5.3
Water Control,
Management
including
Groundwater,
Stormwater
and
Leachate
The operation of the groundwater, stormwater and leachate management systems
represent good practice. The results reported in the draft TCL Annual Report
indicate no water-related off-site impacts.
The stormwater management system works effectively and no signs of either major
erosion or stormwater quality issues are evident. However, surface drains require
regular maintenance to remove sediment as the local soils are quite erodible. This is
5
important, particularly those drains located immediately above the liner (e.g. north
side of Phase 2C and 2B). If these drains overtop water could potentially leak
beneath the liner and cause damage to the subgrade.
The siltation dam has worked effectively to control erosion, and grassing of slopes
has also helped reduce effects.
The PRP has no reason to believe that current
stormwater systems are not appropriately engineered.
The surface water quality data indicate no impact of the landfill on surface water.
The pH in surface water continues to be higher than historical values, but well within
acceptable limits. An anomalously high reading of ammonia-nitrogen on 28
September 2010 was followed with additional sampling on 15 October 2010. The
additional sampling did not show high ammonia-nitrogen. A walk over was
conducted to identify potential sources of the ammonia. No definitive conclusions
were reached. Because neither high conductivity nor chloride was found when the
high ammonia was measured gives confidence that a pulse of leachate was not
responsible for the anomaly. This is all considered good practice in response to
anomalous monitoring results. Further testing was recommended, but it is not clear
to the PRP if it had been conducted. Follow-up testing as recommended in the letter
of 29 October 2010 is advised.
Groundwater quality data from bores outside of the landfill indicate no impact of the
landfill. The occasional high concentrations of various constituents appear to either
represent natural variability or sampling/analytical errors. The absence of high
concentrations of multiple constituents implies no landfill impact on groundwater.
Substantial data now exist from groundwater monitoring, and the PRP would
recommend a change to well-specific trigger levels.
The PRP has received the latest leachate reports35,36. The large exposed surface area of
the landfill in 2009-2011 has aggravated the management issues associated with large
quantities of leachate. Recirculation of leachate is undertaken at the Landfill. The reshaping of the landfill has limited the ability to recirculate leachate into surface soils.
Wet weather over July – September 2010 also affected the ability to irrigate leachate
into the landfill. Consequently the majority of leachate has had to be trucked off site.
Recirculation was initially via sumps, but has now changed to trenches and a K line
irrigation system which have been found to be more effective. In addition, leachate
has been disposed of into pits excavated for special waste. There has been a big
increase in the number of special waste pits since the earthquakes in 2010 and 2011
and these have been effective for disposal of leachate. This is considered acceptable.
The PRP understands that irrigation of fresh waste with leachate is now under trial.
This practice has not been observed yet by the PRP and will be discussed in the next
PRP report.
Groundwater drains are functioning adequately. Flows for the period July 2010 to
June 2011 are summarised in Appendix O of the Landfill Annual Report8. We
recommend that future reports include a plot of the complete historical flow record.
6
Flows have increased with expansion of the Landfill into Phase 2C and extension of
the groundwater drains, as would be expected. Monitoring indicates increased flow
following some rain events in July, August and September 2010 and corresponding
reduced levels of conductivity, particularly notable after the July rainfall event which
was significant (102.2mm in 48hour period). This behaviour is related to additional
infiltration into the groundwater drains. No contamination of the groundwater
drains has been detected. Flushing of leachate drains was undertaken in December
2010.
Based on the information provided in the Landfill Annual Report8 and occasional site
visits, the PRP has no reason to believe that there are any environmental emissions of
concern.
5.4
Landfill Gas
The landfill gas system became operational during this reporting period. After
installation of the wells, it was clear that there was significant production of landfill
gas over much of the landfill. There is a common odour of landfill gas at the site.
This indicates that there is a need to expand the landfill gas collection and flaring
system. The first Landfill Gas Report has been released31. The form and content of
the report is good practice for a facility of this size. The report shows a number of
times and locations where a 0.5% methane surface reading has been exceeded. It is
not clear if these are at compliance points or not with respect to condition 7 of
resource consent CRC021915. Monitoring should be undertaken to confirm that gas
emissions meet consent conditions, and changes made to the gas collection and
flaring system to ensure compliance. Landfill gas emissions would be expected to
decrease once final cover is installed. Because the landfill has had waste deposited
over such a large area early in its life, it has been difficult to install final cover.
Design and installation of final cover should be seen as of increasing importance.
5.5
Compaction, including Method and Degree
The compaction procedures, as described in the LMP1, represent good, current
practice. Appropriate and robust techniques are in use to monitor compaction, and
limited site visits indicate that appropriate compaction methods are in place. In
addition, the attention paid at the site to small working faces and regularly sized
daily cells has aided compaction and is commendable. The PRP has no reason to
believe that current compaction operations are not appropriate.
5.6
Waste Acceptance
The waste acceptance procedures, as described in the LMP1, represent good, current
practice. On the basis of limited site visits and the LMP, the current system appears
clear and comprehensive with thorough documentation. The overview of waste
acceptance issues in the Annual Plan is appropriate. CWS should continue to track
problematic wastes and provide annual assessments to the PRP of their rate of
occurrence. This information is not in the 2010/2011 Annual Report. The PRP has no
reason to believe that the waste acceptance system in place is jeopardising human
health or the environment.
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5.7
Cover Materials
The procedures for use of cover soil, as described in the LMP1, represent good,
current practice. Based on limited site visits, the PRP believes that application of
daily cover is good. There are periods when the site generates substantial amounts of
on-site litter. The site appears to receive the attention needed after these periods and
no ongoing issues of wind-blown litter are evident. Remoulding of old landfill
during 2010 led to significant areas covered by a mix of waste and soil for a
significant time. There seemed strong potential for bird or rat infestations to result.
The vermin surveys indicate no vermin problems. The risk of vermin infestations is
great enough that the Landfill should not reform fill in a way that exposes a mix of
waste and soil at the surface.
In this reporting period CWS adopted a thicker daily cover (0.3m) and have
increased the intermediate cover to 0.5m thick and now use regolith stockpile
material rather than Type 1B so as to achieve a lower permeability. This
modification is endorsed. It will also assist in the containment of landfill gas. Daily
cover is either unsuitable materials or Type 1B material where trucks are required to
traffic. The LMP should be modified to reflect the amendments to cover soil.
5.8
Monitoring, Modelling and Records
The LMP has been recently updated1. The PRP has been provided most of this
document, but has not been provided Section 5 on Monitoring or many of the
appendices. In June/July of 2012, the PRP will participate in revision of the
document.
The Landfill Annual Reports to the regulatory authorities2-8 provide monitoring data.
Taken together, they represent good landfill practice. Based on site visits and the
data provided, the PRP has no reason to believe that thorough monitoring and
record keeping related to the consents does not occur.
Four settlement markers have been installed for monitoring of the Landfill in the
period covered by this report bringing the total number to sixteen. Settlement of
refuse can be significant and the monitoring will assist with calibrating settlement
predictions, so that the settled landfill profile will be close to design expectations. A
plan outlining the proposed monitoring and interpretation, and how this information
will be utilised in the design of the Landfill, should be provided to the PRP. CWS are
developing a settlement model based on monitoring results and other information on
settlement of refuse. The model will be used to assist in determining the
construction profile so that the long-term settled profile will be close to design
expectations. The work is ongoing and will involve review by the Landfill Designer.
Another aspect of ‘good practice’ with respect to records is documentation of work.
The lack of timeliness of documentation indicates an inability to maintain good
industry practice. There has been a notable improvement in documentation in this
reporting period and a very large backlog of work has been greatly reduced. There
are still a few reports that are overdue:
8
1. Water Supply Dam: Operation, Maintenance and Surveillance Manual (expected
August 2008, draft received in September 200929)
2. Sediment Dam: Operation, Maintenance, and Surveillance Manual (expected
September 2009)
3. Phase 2C Construction Report (expected October 2009, draft of main report
received February 201023, appendices received November 2011)
4. Phase 2B Design Report26 (expected, May 2012, draft received March 2012)
Although there has been great improvement in the past year, the ongoing nature of
the inability to prepare adequate timely documentation indicates either a lack of
priority to the matter, or a general understaffing of the people needed to conduct the
work for the site. If the backlog cannot be eliminated in the next reporting year, TCL
should consider hiring additional staff, or letting additional contracts for work.
5.9
Rehabilitation
The PRP has not previously reported on the adequacy of rehabilitation at the site.
Because of the long-term nature of the rehabilitation plans in place, it was not
believed warranted. The PRP believes that now is a good time to begin reporting on
rehabilitation. The current PRP members do not have the expertise to comment on
the rehabilitation. Before the next report, the PRP will examine the appropriateness
of adding an expert to comment on rehabilitation efforts at the site.
6. Managing Hydration Level of GCL: (Condition 22, CRC021914)
CWS and T&T have a methodology37 for evaluating the degree of hydration of the
GCL so as to determine if it is within design limits. The results presented in previous
Landfill Annual Reports indicate compliance with the condition.
Four samples were taken from just below the northern RL250 bench in Phase 2C on
the 22 August 2011. Detailed test results are provided in Appendix E of the 2011
Landfill Annual Report8. The samples had a water content of close to 20% and
exhibited no evidence of significant hydration. The measured water content is well
below the assumed design water content of approximately 50% necessary to reach
full clay hydration.
On the basis of the test work undertaken by T&T on samples obtained in August
2011, and reported in Appendix E of the 2011 Landfill Annual Report8, we confirm
compliance with CRC021914 Condition 22.
Because compliance with this test requires cutting and then repair of the carefully
constructed liner, the PRP is concerned that ongoing monitoring to meet this
condition could jeopardise the long-term integrity of the liner. The PRP recommends
that TCL examine alternative methods of meeting the intent of this condition and
have an alternative condition accepted by the councils.
9
7. Water Supply and Silt Dams (Condition 14, CRC 021919)
This condition (Appendix 1) relates to design and construction in an earlier reporting
period and is discussed in the PRP’s Annual Report No. 1. The PRP considers that
Condition 14 has been met. The PRP has not received any dam monitoring results.
The PRP assumes that both structures are being monitored in accordance with
NZSOLD Dam Safety Guidelines, and that results have been within design
expectations.
Construction reports and as-built drawings for both dams are long overdue and
should be produced with urgency. Tony Pickford conducted an initial review of the
available documentation for both dams in April 2010 and concluded that there was a
need to finalise all documentation and records for the ongoing management and care
of both dams. The current information gaps preclude informed comment in this
report and this will be reported on in the next Peer Review Panel Report. This is part
of a larger lack of timely documentation noted in section 5.8 of this report.
8. Sedimentation Dam Slope Stability (Condition 13, CRC 021919)
This condition (Appendix 1) relates to work in a previous reporting period and is
discussed in the PRP’s Annual Report No. 1. The PRP considers that Condition 13
has been met.
9. Stability of Northern Access Road (Condition 48, RC 020069)
It is understood that this condition relates to the perimeter access road that will be
constructed in the next few years. It is likely that the design work for this part of the
site will be undertaken in 2012/2013. The investigation and detailed design of this
work will be subject to specific review at that time.
10
10. References
The list below gives the key documents (and dates of issue) available to/referenced
by the PRP for Annual Report Number 7. The documents have been re-ordered by
topic. The documents received since the release of the last PRP report are repeated in
a list at the end.
Landfill Annual Reports and Landfill Management Plan
1. Landfill Management Plan, Issue 2, September 2011, by Transwaste Canterbury,
incomplete.
2. Landfill Annual Report to 30 June 2005, September 2005, by Transwaste
Canterbury.
3. Landfill Annual Report to 30 June 2006, September 2006, by Transwaste
Canterbury.
4. Landfill Annual Report to 30 June 2007, November 2007, by Transwaste
Canterbury.
5. Landfill Annual Report to 30 June 2008, December 2008, by Transwaste
Canterbury.
6. Landfill Annual Report to 30 June 2009, received 12 February 2010, by
Transwaste Canterbury.
7. Landfill Annual Report to 30 June 2010, May 2011, by Transwaste Canterbury.
8. Draft Landfill Annual Report to 30 June 2011, received 14 February 2012, by
Transwaste Canterbury.
Phase-by-Phase Design and Construction Reports
9. Phase 1A-1 Design Report, 22 September 2004; plus amendments of 14 March
2005, by Tonkin & Taylor Ltd.
10. Phase 1A-1 Construction Report, September 2006, by Tonkin and Taylor Ltd.
11. As-built geology of the Cell 1A footprint and middle valley areas of the
Canterbury Regional Landfill, Kate Valley, North Canterbury, April 2005, by
Geotech Consulting Ltd.
12. Phase 1A-2 Design Report, 26 June 2009, by Tonkin and Taylor Ltd.
13. Phase 1A-2 Construction Report, reissued, October 2011, by Tonkin and Taylor
Ltd.
14. Phase 2A Design Report, reissued, September 2011, prepared by Tonkin & Taylor
Ltd.
15. As-built geology, Phase 2A construction works, Kate Valley Landfill, North
Canterbury, August 2008, by Geotech Consulting Ltd
16. Phase 2A-1 Construction Report, August 2011, prepared by Tonkin and Taylor
Ltd.
17. Phase 1A-3 Design Report, October 2011, prepared by Tonkin and Taylor Ltd.
18. Phase 1A-3 Drawings, Issue 2, October 2009, by Tonkin and Taylor Ltd.
19. Phase 1A-3 Construction Report, October 2011, prepared by Tonkin and Taylor
Ltd.
20. Phase 2C-1B Figures, 4 November 2008, by Tonkin and Taylor Ltd.
21. Phase 2C-1B Drawings, 5 December 2008, by Tonkin and Taylor Ltd.
11
22.
23.
24.
25.
Phase 2C Design Report, October 2009, prepared by Tonkin and Taylor Ltd.
Draft Phase 2C Construction Report, October 2009, by Tonkin and Taylor Ltd.
Phase 2C Construction Report Appendices, by Transwaste Canterbury, 2011.
As-built geology, Phase 2C Construction Works, Kate Valley Landfill, North
Canterbury, May 2009, by Geotech Consulting Ltd.
26. Draft Phase 2B Design Report, received 7 March 2012, by Transwaste Canterbury.
27. Draft Phase 2B Drawings, received 7 March 2012, by Transwaste Canterbury.
Dam Reports
28. Kate Valley Landfill Silt Dam: Construction Testing Review, September 2009, by
Tonkin and Taylor Ltd.
29. Draft Kate Valley Landfill Water Supply Dam: Operation, Maintenance, and
Surveillance Manual, September 2009, by Tonkin and Taylor Ltd.
Landfill Gas Reports
30. Phase 1A Landfill Gas Management System Design Report, November 2006, by
Tonkin and Taylor Ltd.
31. Draft Landfill Gas Annual Report to 30 June 2011, received 13 March 2012, by
Transwaste Canterbury.
32. Landfill Gas As-Built Drawings as of 30 June 2011, received 12 April 2012, by
Transwaste Canterbury.
Landfill Leachate Reports
33. Leachate Report to 30 June 2008, November 2008, by Transwaste Canterbury.
34. Leachate Report to 30 June 2009, received 12 February 2010, by Transwaste
Canterbury.
35. Draft Landfill Leachate Report to 30 June 2010, received 13 March 2012, by
Transwaste Canterbury.
36. Draft Landfill Leachate Report to 30 June 2011, received 13 March 2012, by
Transwaste Canterbury.
Other Reports
37. Draft GCL Hydration Condition and Related Inspection Procedure, 16 December
2005, by Tonkin and Taylor Ltd.
38. Review of Groundwater Divide and Baseflow Changes at Kate Valley Landfill,
September 2009, by Pattle Delamore Partners.
Documents received since the last Peer Review Panel report.
A. Phase 1A-2 Construction Report, reissued, October 2011, by Tonkin and
Taylor Ltd., received 26 October 2011.
B. Phase 2A-1 Construction Report, August 2011, prepared by Tonkin and
Taylor Ltd., received 2 September 2011.
C. Review of Groundwater Divide and Baseflow Changes at Kate Valley
Landfill, September 2009, by Pattle Delamore Partners, received 2 September
2011.
D. Phase 2C Design Report, October 2009, prepared by Tonkin and Taylor Ltd.,
received 2 September 2011.
12
E. Phase 1A-3 Design Report, October 2011, prepared by Tonkin and Taylor
Ltd., received 26 October 2011.
F. Phase 2A Design Report, reissued, September 2011, prepared by Tonkin &
Taylor Ltd., received 26 October 2011.
G. Phase 1A-3 Construction Report, October 2011, prepared by Tonkin and
Taylor Ltd., received 4 November 2011.
H. Phase 2C Construction Report, appendices provided by Transwaste
Canterbury, received 4 November 2011 (no final version of main report
provided).
I. Draft Landfill Annual Report to 30 June 2011, by Transwaste Canterbury,
received 14 February 2012.
J. Draft Phase 2B Design Report, by Transwaste Canterbury, received 7 March
2012.
K. Draft Phase 2B Drawings, by Transwaste Canterbury, received 7 March 2012.
L. Landfill Management Plan, Issue 2, September 2011, by Transwaste
Canterbury, incomplete, received in part 13 March 2012.
M. Draft Landfill Gas Annual Report to 30 June 2011, by Transwaste Canterbury,
received 13 March 2012.
N. Draft Landfill Leachate Report to 30 June 2010, by Transwaste Canterbury,
received 13 March 2012.
O. Draft Landfill Leachate Report to 30 June 2011, by Transwaste Canterbury,
received 13 March 2012.
P. Landfill Gas As-Built Drawings as of 30 June 2011, by Transwaste
Canterbury, received 12 April 2012.
13
Appendix 1
Consent Conditions Relevant to PRP
General Consent Condition 11
The Consent Holder shall establish, at its own cost, an Independent Peer Review
Panel, to review the design, construction, operation and after-care of the Landfill and
to assess whether or not the work is undertaken by appropriately qualified personnel
in accordance with good practice. The Independent Peer Review Panel shall
comprise at least two persons who shall be:
 independent of the Consent Holder
 experienced in landfill design, construction and management
 experienced in landfill geotechnical, groundwater and surface water aspects
 recognised by their peers as having such experience, knowledge and skill
 approved in writing by the Hurunui District Council and the Canterbury
Regional Council.
General Consent Condition 12
The Independent Peer Review Panel shall prepare an annual report for the Consent
Holder on the adequacy of the following matters:
 management and monitoring plans
 site preparation, including hydrogeological and geotechnical issues
 liner design and construction and use of on-site materials
 water control, including stormwater and leachate management
 compaction, including method and degree
 waste acceptance
 cover material used
 monitoring, modelling and records
 rehabilitation
The Peer Review Panel shall take into account the matters covered by CRC021914
Condition 22, RC020069 Condition 48, CRC021919 Condition 13 and CRC021919
Condition 14 and address any issues arising.
General Consent Condition 13
Where the Independent Peer Review Panel does not have the expertise in any of the
areas it is required to report on, as detailed above, it may, with the agreement of the
Consent Holder and Canterbury Regional Council, engage the services of an
appropriate expert to report on the relevant matter to the Independent Peer Review
Panel. The report shall form part of the review provided by the Independent Peer
Review Panel as required by the condition. Copies of all reports shall be sent to the
Consent Holder, Hurunui District Council and Canterbury Regional Council by 1
October each year.
CRC021914 Condition 22 (formerly Special Condition 1)
The applicant shall prepare a detailed Management Plan to control, manage and
monitor the hydration level of the GCL liner so as to maintain it within the design
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standard. A suitably qualified geotechnical engineer shall inspect the edges and any
exposed parts of the liner system, on at least an annual basis, and after weather
events capable of causing surface water infiltration, in any situation where such
infiltration has occurred and at the completion of each stage of filing. The
geotechnical engineer shall provide an annual report to the consent holder, and the
Regional Council and shall provide certification that the degree of hydration is
within design limits and that in his or her view the degree of hydration does not
result in any elevated risk of mass failure. The Management Plan shall outline the
processes to be followed in the event that such certification cannot be provided. This
shall include a process for deciding whether further development of the landfill can
safely occur and for determining appropriate mitigation measures. (Copies of the
management plan, report, and certification are to be provided by the consent holder
to the Regional Council and to the Peer Review Panel within seven days of
completion of the document.) In the event that the certification outlined above
cannot be obtained at the end of any phase of filing, subsequent stages shall not
proceed until redesign work demonstrates that a satisfactory level of stability can be
assured and certified by the design engineer (such certification to be provided to the
Peer Review Panel and the Regional Council).
RC020069 Condition 48 (formerly Special Condition 2)
In the area upgradient of deep cuttings along the northern access road which will
have its toe support removed, all soil material above the Tokama Formation (soft
rock) shall be removed prior to excavation of the cuttings. The lateral extent of the
soil removal shall be defined by the points to the east and west of the cutting where
the soil is undercut by the final excavation. The upgradient extent of the soil removal
shall be determined during the final investigation of this area (prior to final design)
and shall be certified by the design engineer as having a factor of safety of at least 1.2
(see AEE). (A copy of such certification to be provided to the Peer Review Panel and
to the Regional Council.) Prior to excavation of the deep cutting into the Tokama
Formation at these two locations, an investigation of the rock slope stability of these
areas shall be carried out taking into account the unfavourable bedding at these
locations. The design engineer shall certify that the rock cuttings have a factor of
safety (FOS) greater than 1.1 under both design groundwater conditions and design
earthquake loadings. (A copy of such certification to be provided to the Peer Review
Panel and to the Regional Council.) In the event that stability cannot be certified
(FOS > 1.1) under “Design Earthquake Loading and Design Groundwater Levels” the
potentially unstable rock mass shall be excavated to provide a stable batter over the
life of the landfill and its extended after care period.
CRC021919 Condition 13 (formerly Special Condition 3)
Prior to construction of the Siltation Control Dam an investigation of the slopes
adjoining the dam embankment footprint and the pond area shall be carried out to
assess the long-term stability of these batters. This investigation work shall take into
account the result of the required detailed investigation of the proposed siltation
dam and its foundations. The permanent slopes around the siltation pond and
embankment shall be designed with appropriate factors of safety for design
groundwater and seismic loadings. Where natural slopes exhibit potential mass or
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shallow instability the slopes shall be stabilised by soil removal, buttressing,
drainage, or such other measures as determined to be necessary. The design
engineer shall prepare a report addressing the design of these slopes that shall be
provided to the Peer Review Panel and to the Regional Council prior to construction.
CRC021919 Condition 14 (formerly Special Condition 5)
Both the siltation control dam and the water storage dam shall be investigated and
designed in accordance with the New Zealand Dam Safety Guidelines as
promulgated by the New Zealand Society on Large Dams (as agreed by the
applicant). The investigation, design, peer review and monitoring of the dam shall
take into account the following factors:
 the public are known to frequent the lower end of Kate Valley and the beach
at the Kate Creek outlet
 the potential incremental consequences of failure in terms of socio-economic,
financial and environmental matters would cause major damages in that the
landfill would likely need to be closed, requiring extensive rehabilitation
work.
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Appendix 2
Dates of PRP Meetings and Site Visits in this Reporting Period
(1 July 2010 – 12 January 2012)
16 July 2010 (meeting with Transwaste Canterbury Board)
25 August 2010
14 September 2010
2 February 2011
2 June 2011
2 September 2011 (meeting with Transwaste Canterbury Board)
26 October 2011
12 January 2012 (Trevor Matuschka site visit)
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