TIROHIA LANDFILL : STATE OF THE ART LANDFILLING

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1 WASTEMINZ 13 TH ANNUAL CONFERENCE TIROHIA LANDFILL : STATE OF THE ART LANDFILLING Authors: Eric Souchon General Manager, HG Leach & Co. Ltd Dean Kimpton Director, Management Consulting, Meritec Ltd Background The opportunity to expand the quarry business and diversify into solid waste by HG Leach & Co. Ltd began in late The existing quarry at Tirohia was reaching the end of its current stage of quarryable resource, thus leaving a void needing rehabilitation and presenting the opportunity to further develop the site. Since then the company in pursuit of this development has taken the application through 2 consent hearings, 2 Environment Court hearings, and until 21 September 2001 was awaiting the outcome of an appeal by Ngati Hako to the High Court. This has now been struck out. In this presentation we will describe: unique features significant design challenges. Construction challenges lessons learnt (refer attachment #1 showing the site and key locations) Overview Tirohia Landfill represents a new generation of landfill in New Zealand, and is the first private, modern, landfill in the Waikato Region. This site is located some 7 km southwest of Paeroa, Thames Valley. The site has been and still is an active quarry operation producing different grades of aggregate. The Tirohia Quarry / Landfill site is well located in the area extending across the Western Bay of Plenty, Tauranga, Thames Coromandel, Hauraki and Matamata Piako districts. As such it is well situated to help address the chronic shortage of land filling space in the Waikato and Western Bay of Plenty regions. The Tirohia landfill is ideally situated in the worked out or exhausted portion of an operational quarry, well screened, remote from ground and surface waters, and potentially affected neighbours. At the time of writing it is under construction, with a projected opening date of mid October 2001.

2 The Site Today (refer video clip of Tirohia Landfill with pre and post development scenarios) (refer to photo presentation of landfill in varying stages of construction) In our presentation we describe using the above graphics: location of landfill / development of landfill within the existing quarry pit current status of landfill construction unique features that differentiate the site make it well suited for landfill development Unique Features Significant benefits / features of the site were: (i) Design Philosophy the design is based on current modern practice design standards, including provision of an HDPE liner system the site is a non-hazardous municipal solid waste site (ii) Natural attributes: the landfill is not a green fields development, as the site is highly modified from almost 70 years of quarrying the site is in an excellent location some 60 metres above ground water level and at least 400 m distant from the site boundary and within an existing quarry pit the hydro-geological model predicts 70 to 80 years travel time for any escaped leachate to arrive in the groundwater and at least some 140 to 160 years to reach the site boundary the operation is very well screened within an existing quarry pit and operation clay liner and cover materials are available on the site and do not need to be imported the Company owns significant farmland and forests around the quarry & landfill site, providing a buffer between itself and its neighbours (ii) Social / Community Features with the exception of some local iwi, it had wide community support. there were some 440 submissions lodged in support of the quarry and landfill land use consent applications (iii) Relationships the company has an established relationship with the land and community of over 50 years.

3 the company has a long history and demonstrated commitment to supporting the local community, with the company s shareholders all still living in the local districts Design Challenges Significantly, the greatest challenge in design has been that of the sideliner. A further challenge was that of tight deadlines to complete the detailed design, undertake the peer review and obtain Council approvals and building consents, whilst not delaying the construction with the onset of winter! The Environment Court issued its Interim Decision upholding the grant of consent late in January 2001, and finally released the consent conditions on 27 April Construction commenced in June The sideliner, being near vertical, that is 6V:1H, the design and constructability of a natural clay liner on a benched quarry face was a significant challenge. Because of its steepness it also enhanced the void capacity available for filling. Key characteristics / risks for discussion include: steepness and associated construction difficulty potentially loose fragments of rock from historical blasting/quarry activity the ability to ensure that the clay liner met the permeability requirements of the conditions of consent that differential settlement and thus drag forces of settling refuse did not undermine the structural integrity of the liner the potential for perched leachate to leak and the potential effect of this risk of refuse penetrating the side liner system and compromising it consideration of alternatives and why clay was selected Construction Challenges Winter Construction Due to the delays resulting from the court hearings and the pressure to provide an operational landfill facility construction has occurred over the winter months, being June to October. Key issues: completion of the detailed design, peer review and Council approvals with minimum delay inclement weather and the ability to progress the works without compromising quality, at an acceptable price flexibility, co-ordination and synergy with quarry operations having alternative methods and options at our disposal including variations to consents conditions, these included: approval and use of GCL in construction, lime

4 stabilization of natural clay, geo-fabric alternatives to sand protection layers, and emulsion seal replaced bitumen for chip seal to minimise delays to construction steep and confined working space for sideliner construction good co-operation and communication between the designers and the client / contractor careful selection of resources, particularly men and equipment Lessons Learnt (i) getting consent The challenge of securing consent for modern landfill facilities is significant under the current legal environment and community perceptions about them. However, there are a number of key lessons learnt in the process of securing consent for this facility. These lessons are: take a long term view Expect to end up in Environment Court and build your application and case based on this assumption. importance of a robust and defensible technical case. Do your homework up front. Get it right, ensure your technical case is well researched, understood and articulated. Undertake a risk assessment of your case. Do not get seduced by theory take a pragmatic approach to ensuring you understand what it is going to take to win and likewise lose your case. consultation Fundamental. Ensure the consultation record is clear and well articulated, and it is undertaken in good faith. Keep detailed records of all consultation, making sure there is a clear audit trail to present to any hearing. Address opposing and favourable submissions. Whilst in assessing the application it is the nature of the issues raised, the number of submissions should not be overlooked. It is also about perception and weight. (ii) Environment Court The Tirohia Landfill was challenged on two key matters: iwi cultural issues

5 On this matter there was a fundamental and in the end irresolvable difference of opinion as to whether the site was suitable for landfill development as - or not, and potential effects on actual/perceived artefacts. Significant oral and historical written record was presented at consent and Environment Court hearings for local iwi and HG Leach respectively. On the matter of this case, Salmon reports in its annotations the following: Kaitiakitanga s7 Cases involving Maori values require individual assessment without there being any overriding presumption that tangata whenua may effectively veto a proposal. Issues of wahi tapu require weighting and determination objectively in the circumstances, without allowing the pressure of concerted and sustained opposition to achieve a predominant influence and deter an appropriate outcome consistent with the Acts overall purpose.. Te Kupenga O Ngati Hako Inc v Hauraki D.C. & Waikato R.C. A010/01, 6 NZED 232. In essence the lessons learnt on this matter have been: ensure a well documented consultation programme research historical documentation, in this case research into the original Maori Land Court decisions was undertaken. In essence, and the Courts decision supported this, it is essential that any party bringing evidence to the Court meets the required evidential standards. cumulative effects of a combined quarry and landfill activity. The original application assumed the baseline for consideration of environmental effects was the working quarry and that the effects assessment could take this as the baseline. In effect it presented an assessment of the potential effects of a combined quarry and landfill operation. The Court made an interim decision, finding that the assessment of effects did not address adequately the effects: of a quarry operation in the absence of a landfill should consent for the combined landfill and quarry operation not be granted, and the combined effects of a landfill and quarry operation a subtle difference to that applied for but designed to ensure that the effects of traffic and cumulative effects were picked up in particular. This decision resulted in preparation of two separate applications designed to address the above issues. No regional consent matters were at stake. These went through a council hearing and then into the Environment Court a year later to be heard in conjunction with the remainder of the case.

6 Conclusion Tirohia Landfill is an excellent example of a regional landfill, ideally situated in an existing highly modified quarry environment. The location lends itself to this sort of development providing natural protection to the environment. It is also an up to date example of the challenges associated with securing consent for a modern landfill operation even with outstanding and favourable technical features, and significant public support.

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8 The Quarry Pit Leachate Trench Construction

9 Liner Construction Pit Prior to Lining