MERIDIAN ENERGY - HURUNUI WINDFARM. REVIEW of ENVIRONMENTAL MANAGEMENT PLAN

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1 EROSION MANAGEMENT EROSION MANAGEMENT LTD. 35 HASTINGS PARADE. P 0. BOX DEVONPORT, AUCKLAND, NEW ZEALAND TEL; FAX; MERIDIAN ENERGY - HURUNUI WINDFARM REVIEW of ENVIRONMENTAL MANAGEMENT PLAN Executive Summary The Environmental Management Plan (EMP) is a master plan to identify processes and techniques to achieve effective environmental management. It is linked to the Construction Effects and Management Report (CEMP) which addresses the construction orientated aspects of the project. Some of the construction methodologies also address environmental objectives. The EMP covers a large range of activities in a succinct manner. One of the key initiatives proposed by the EM is the preparation of Supplementary Environmental Management Plans (SEMPs). These are proposed to ensure that an appropriate level of environmental management is applied and are to be location or activity specific. The concept of this approach is supported although some reservations are held over some aspects of their preparation and application. A significant focus of the EMP is on erosion and sediment control and the document presents a number of measures proposed for common usage. Some of these are considered to be reflective of best practice while perhaps others are not so representative. The EMP does not establish a process by which regard can be had to matters such as soil type, sediment yield risk, particular environmental values, staging and season of works etc when the appropriateness of particular control measure(s) are to be considered. One of the erosion and sediment control conclusions from the review is that EMP does not propose specific control strategies to address particular issues, but instead appears to propose controls that will apply across the project. Overall it is considered that the EMP establishes a process by which SEMPs are to be used to achieve environmental outcomes. This approach is supported. It is considered that the EMP could be reviewed to better reflect best practice erosion and sediment control measures, and that more specific processes could be established by the EMP by which to guide the preparation and standard of the SEMPs.

2 1.0 Extent of Review has been requested to undertake a peer review of the EMP for Meridian's Project Hurunui Wind. The review is to indicate missing information or inconsistencies, and to provide an assessment of any methodology used and conclusions drawn. This aspect of the review is discussed in section 4 below. The review is also to check that mitigation measures listed in the CEMP are addressed in the EMP - this is discussed in section 5. A brief summary of relevant portions of the overall project is outlined in section 3. The EMP is appended to the CEMP and both documents are considered together in this review as relevant information is contained in both. This is not unexpected because of the influence construction methodology can have on environmental outcomes. Reference is made to the CEMP in this review but the main emphasis is on the EMP as requested. The Assessment of Environmental Effects (AEE) has been referred to in order to gain an appreciation of environmental considerations. This review does not attempt to identify or discuss every aspect of the EMP. Instead comment is made on those aspects of the project considered the most important to achieve good environmental outcomes. Brief details of the reviewer are attached as Attachment 1 at the end of the report. 2.0 Reference Documents The following documents have been assessed as part of this review: The project's CEMP. February The draft EMP for Meridian's Project Hurunui Wind. August 2010 The report 'Ecological Values and Assessment of Effects' (the AEE). February The Environment Canterbury Erosion and Sediment Control Guideline 2007 (ECan guideline). A site inspection has not been undertaken. 3.0 Project Overview The project proposes to develop a 33 turbine windfarm on steep land north of Christchurch. Approximately 22.5 km of reading is proposed (17 km of new reading) with some of this on steep grades. Some 773,000m3 of cut earthworks is proposed which includes 435,000m3 of reading and 225,000m3 of turbine platform. The proposed works will extend over some 69 hectares1 that will include 30.5 hectares of reading and platform surfaces and potentially 31 hectares of spoil fill sites2. The project expects a lesser volume/area of fill sites will actually occur because of a proposed cut-to-fill approach during construction (p25 CEMP). 1 Final volumes and bare area may vary from that stated in the project documents because the documents assume full cut-to-waste whereas cut-to-fill earthworks is proposed in practice Any additional bare land that may occur from other activities, such as haul routes, topsoil stockpiles etc, has not been included. 2 There is some inconsistency in the references to volumes and bare areas throughout the CEMP. The AEE has different values again e.g. p49 AEE. The information used in this review is derived from Table 14 (p38 CEMP). Hurunui Windfarm - EMP Assessment 8 April 2011

3 The main earthworks are programmed to occur over an 8 month period (p51 CEMP). An 18 month construction period is anticipated (p50 CEMP). The AEE considers most of the aquatic receiving environments to be in relatively poor condition (p15 AEE). The AEE considered the lower Motunua River and Tipapa Stream to be the two perennial systems with the greatest permanent habitat potential (p 23 AEE). Of these two systems, the AEE considers that it is the upper kilometre of headwaters that potentially will be the most affected from sediment (p23 AEE). 4.0 The EMP 4.1 Overview The EMP covers a considerable number of activities and only the more key elements have been selected for comment below. The EMP sets out to address the project's environmental proposals to ensure compliance with contractual and consent requirements and with Meridian's environmental objectives. The objectives of the EMP (p1 EMP) are to: provide environmental management guidance; ensure compliance with consents and other requirements; avoid, remedy and mitigate adverse environmental effects. The EMP describes itself as a master plan identifying the processes and techniques proposed for use to ensure effective environmental management (p1 EMP). A large number of activities are addressed ranging from blasting to fire prevention. It is a mix of relatively high level direction (such as outlining how the EMP will work), and detail (such as the storage of fuels). A significant proportion of the EMP (39.5%) is directed to erosion and sediment control3. The EMP covers the wide range of activities in a concise and succinct manner. It is noted that it makes no mention of avifauna matters (although a separate AEE has been prepared on this). It is understood that the EMP will be amended should resource consents be granted with the EMP commenting that the relevant consent conditions will be identified and addressed in the final document. It is recognised that it can be difficult for a development to propose specific control systems, particularly for large and complex projects such as this, when the final design has not been completed. On one hand the development needs to provide enough certainty so approval agencies can have confidence that future requirements can be met; on the other hand some flexibility is necessary so that the inevitable changes that occur over time can be accommodated. The EMP proposes to address this through the preparation of Supplementary Environmental Management Plans (SEMPs). These are to be prepared for particular locations or activities and used to 'flesh' out the overall intention of the wider documents. Seven such SEMPs have been identified in situations ranging from track and platform construction to the possible operation of a concrete batching plant. To illustrate the intent of the EMP an example SEMP has been prepared for a particular area and has been appended to the EMP (Appendix C). Preparing an example SEMP in this manner is considered an appropriate manner in which to address the potential uncertainty when the final design of large projects has not been completed. It is a manner how the project can 3 Revegetation is included because it is a key erosion control procedure. Hurunui Windfarm - EMP Assessment 8 April 2011

4 demonstrate how future environmental objectives can be met and, as such, the concept is supported. SEMPs are considered a very important aspect of the proposed environmental management of the project and are discussed in more detail below in section 4.2. The EMP proposes that auditing of environmental control systems be undertaken by internal staff with council staff invited to participate (p43, CEMP). The EMP does not appear to propose that council presence or auditing be mandatory {the councils may not want this anyway) but the suggestion that the site may be self-auditing does raise the question of standards and certainty of outcome. Should the councils not wish to undertake regular/storm initiated auditing, perhaps an independent and appropriately skilled auditor approved by the two councils may be an option to consider. The EMP proposes forwarding draft SEMPs to the councils for comment but it does not commit the project to accepting any comments that may be made. In addition, the EMP proposes that the final SEMPs be forwarded to the councils for their information (p42 CEMP) - the EMP is not seeking council approval for these final documents. A similar system is proposed for any amendments to an SEMP (and to the EMP). In essence, it appears as if the EMP is not proposing to be bound by any council comments that may be made to key environmental documents, that it be its own approving authority, and that it undertakes site monitoring with only possible council involvement. This is not considered appropriate for a major project such as this. It is suggested that this be reviewed and that a more appropriate process be established by the EMP. Sediment settling tests of sandy or gravely silt soil are included as Appendix G of the EMP. The tests shows good settling as might be expected from these medium to coarse textured sediments. Best practical option (BPO) control measures, such as sediment retention ponds, decanting earth bunds etc that rely on natural settling of sediments, would be expected to work well with these medium to coarse textured soils. It is assumed that these soils are representative of the overall project- However, it is noted that the example SEMP2 (Appendix C, EMP) refers to a loess over clay soil type (p6, SEMP2) which is different to the soil types tested. Clay soils are very fine in texture, have a negative charge and behave very differently to medium to coarse textured sediments. They are difficult to retain in conventional BPOs and chemical treatment may be required4. The EMP does not discuss the range of soil types that may be present in relation to the project or the effect that these may have on proposed control measures. The example SEMP2 does not appear to have taken this into account despite the AEE identifying the upper headwaters of the receiving environments as being vulnerable to sediment (p23 AEE). It is considered that the EMP should establish a process to ensure that account is taken of matters such as these that could potentially affect environmental outcomes. Matters that could be considered in this respect include soil type, sediment discharge risk and receiving environment values. The CEMP gives an indicative construction timeline (p51 CEMP) which is a useful overview of possible work programming. Environmental risk is involved irrespective of whether large areas are worked at the same time over a shorter duration or whether smaller areas are worked over a longer period. There is environmental risk either way. From the proposed works programme (p51, CEMP), the majority of earthworks are proposed over an 8 month period which implies, from the scale and volume of earthworks, that no staging of works is proposed. The environmental implications of this are not discussed by the EMP. r are the environmental implications of any earthworks that may be undertaken over the winter period. These matters can present significant environmental risk and, given that the EMP is the 4 Chemical treatment of construction stormwater is now sufficiently well understood to be now considered as a best practice control technique. Hurunui Windfarm - EMP Assessment 8 April 2011

5 master plan to achieve effective environmental management, it is considered that at least some assessment of these risks should be included in the EMP. It may be appropriate for the EMP to establish a process to address these issues. Associated with this, it is noted that there may be significant periods when construction may be completed in places but where satisfactory surface stabilisation may not be possible because of adverse climatic conditions (e.g. summers being too dry or winters too cold). Ineffective surface stabilisation directly leads to ongoing sediment generation. Mulch is proposed as one option but this may have limited application on a steep and windy site. The EMP does not currently acknowledge or propose a process to address this issue. The CEMP states that 'the potential impact from erosion, sediment run-off and dust emissions are likely to be minor given the environmental management measures that will be applied' (p40). further discussion of this is present in either the CEMP or EMP. estimate of potential soil loss is given in either document. A cursory estimate of possible soil loss is therefore undertaken in this review to gauge potential sediment yield risk. For this assessment, the area of works is taken to be 69 hectares (from Table 14, p38 CEMP), a 6 month exposure period is assumed overall, a soil loss yield of 168 t/ha/year is assumed (from Auckland information in lieu of local data) and a treatment efficiency rate of about 60% is assessed (from SEMP2, see section below). This very rough assessment derives a net sediment loss of about 2,300 tonnes from the project during the construction period (from 69 hectares x 168 tonnes/ha/year x 0.5 years x 40% loss). This is equivalent to about 33 tonnes discharged from each hectare of bare ground. This is material that will be discharged after treatment assuming no failure of control measures. The use of flocculation over the site would decrease theoretical total sediment yield to about 300 tonnes (assuming 95% efficiency - Auckland information). This is about 4 tonnes of sediment discharged/hectare of bare land and which is significantly lower than that from the more standard BPO approach. This very coarse assessment suggests that there is a significant risk that elevated sediment levels will be discharged from the project as it is currently proposed. An intuitive assessment of the proposed scale of works on the steep country would tend to support this It is considered that this level of risk supports suggestions that the EMP provide a process (or processes) by which factors influencing environmental risk can be considered when formulating SEMPs and consideration of the appropriate control options and procedures for particular areas. This may help address the comment in the AEE that, 'Although the waterways potentially affected by the wind farm are relatively tolerant and robust, they are still of ecological value and will not tolerate substantial quantities of sedimentation generated by earthworks' (p25 AEE). The EMP presumably considers erosion and sediment control to be a key issue as a significant focus of the document is on erosion and sediment control. This is reinforced by the example SEMP which is dominated by erosion and sediment control matters. A Flocculation Management Plan is to be prepared for the project although criteria detailing the use of chemicals have not been established in the EMP. The EMP discusses a number of erosion and sediment control techniques and facilities and includes a number of example photographs. The concept behind this is good. However, it is considered that the control measures outlined in the EMP are of varying standards with some reflecting good current practice while others do not. The CEMP states that measures will be in accord with the ECan erosion and sediment control guideline but the EMP contains no such reference (although the example SEMP2 does refer to the Ecan document). Irrespective of this, the actual design criteria appears to be based more on the Greater Wellington Erosion and Sediment Control Guideline (e.g. the discussion on decanting earth bunds in the EMP, p16; the sizing of sediment retention ponds in SEMP2, p5). Hurunui Wine/farm - EMP Assessment 8 April 2011

6 The overall sense gained from the impressions above is that the EMP does not establish procedures to address particular issues that may be present. Instead it appears that fairly standard control measures are proposed, and that these are to apply project-wide irrespective of particular circumstances. It is again considered that the EMP be reviewed to more thoroughly address the matters discussed above. 4.2 SEMPs General The EMP proposes that location or activity specific SEMPs be prepared where an appropriate level of environmental management is to be applied (p5 EMP). Seven SEMPs are proposed and these appear to address the majority of the proposed project area and particular activities. Site/activity specific management plans such as these are considered key mechanisms to ensure that the direction of the more over arching documents, such as management plans and resource consents, is given effect to on the ground. And because there can be uncertainty with large, complex projects such as this, the proposal to prepare the SEMPs once the final design has been undertaken is also supported. They give the opportunity for site specific methodologies and control facilities to be developed closer to the time of the works. Overall it is considered that they are an appropriate means of demonstrating to councils how the various conditions of consent can be complied with, and they can be prepared in accordance with industry best practice at the time. The concept that site and activity specific SEMPs be prepared after final design and closer to the time of works is therefore endorsed. Because the proposed SEMPs concept appears to be the main process proposed by the EMP to achieve environmental and consent objectives, the standard of preparation and the performance of the SEMPs is important. The EMP proposes that the development of the SEMPs be an interactive process involving contractors, advisors and council staff. The CEMP requires the contractor to prepare this (p42) but the Environmental Management Roles table (p3 EMP) does not identify any particular position as having specific responsibility for SEMP preparation. As a general comment contractors are not necessarily designers, and, with all due respect, may not be the most appropriate party to prepare what will be key environmental documents. Because of the importance of the SEMPs in achieving environmental outcomes, it is considered that SEMPs should apply across the entire project, not only to the areas and activities currently proposed in the EMP. Further comment on SEMP preparation, approvals, monitoring and standards has been made above in section SEMP Area 2 SEMP2 is the example SEMP appended to the EMP. The overall purpose of SEMP2 is not clear in that, on one hand, the CEMP (p42) considers that it has been prepared to demonstrate the intended approach while on the other hand, the front page of the SEMP notes it being 'Provisional for Discussion Purposes'. For the purposes of this review, SEMP2 has been considered as an example SEMP prepared to demonstrate to the councils how environmental outcomes can be achieved. The prime focus of SEMP2 is on erosion and sediment control although reference is made to an area of vegetation to which particular regard is to be had. It does not include the most technically challenging section of road (part of the northern access road - p 18 CEMP). However, it involves some 3 km of reading (7.5 hectares of bare surface), the construction of Hurunui Windfarm - EMP Assessment 8 April 2011

7 6 turbine platforms (approximately 1 hectare of bare land) and 4 hectares of fill area. The total area of bare land for this SEMP is about 12.5 hectares - an area that excludes haul routes, topsoil stockpiles and any other areas of bare land that may arise. The soil type is loess over a variable depth of clay - the loess component {predominately silt) can be expected to be relatively easily settled but not so the clay. The SEMP is located in the headwaters of the upper Motunau catchment; one of the areas identified by the AEE as having the potential to be particularly affected with flow on effects from sediment (p23 AEE). A quick review of the SEMP in relation to erosion and sediment indicates that sizing criteria are not based on the ECan guideline but on what appears to be the Greater Wellington Sediment Control Guidelines5. There is no reference to the ECan guideline's 20 year runoff control requirement, no supporting calculations on channel sizing, and no allowance made for potential deposition in diversion channels (loess, in particular, will quickly deposit in such channels as slopes/velocities diminish). The example SEMP2 does not have any assessment of the appropriateness of selected control measures based on soil type and settling (see above discussion in section 4.1). There has been no assessment of the effectiveness of the proposed treatment measures in relationship to the ecological values of the receiving environment (considered higher than other areas, p56 CEMP, and referred to in the AEE (p23 AEE). It does not address control measures for any other bare areas that may occur such as haul routes, topsoil stockpiles etc. With a large project involving significant earthworks on steep land, construction methodology might be expected to play a big part in erosion and sediment control. There is no discussion ofthisinsemp2. The sediment retention measures over 2/3's of the SEMP (the roads and platforms) are proposed to be grit traps and decanting earth bunds; measures that may not be particularly effective with any fine textured soil particles that may arise such as from the clay component. The more efficient sediment retention ponds are proposed only for the fill sites. If the efficiency of grit traps and decanting earth bunds are assumed to be about 50%, and that of a well constructed pond about 75% efficiency, then the overall average is about 60%. If an equivalent sediment yield assessment is undertaken for this example SEMP as that for the overall project in section 4.1 above, then the estimated level of sediment discharged from the example SEMP is about 400 tonnes (from 12.5/69 hectares x 2300 tonnes). This suggests potentially significant levels of sediment could be discharged from the SEMP2 area of works to environments potentially at risk from sediment. As mentioned above, the concept behind the SEMPs is considered good. However, in this case it is considered that the example SEMP has a number of short comings that are not indicative of best practice. As it is, it is considered that the example SEMP does not demonstrate that the proposed environmental approach will adequately mitigate the potential environmental effects, particularly with the receiving environments considered vulnerable to sediment by the AEE. However it is also recognised that SEMP2 is marked for discussion purposes, and it could be that it does not fairly reflect the proposed approach of the EMP and of project environmental outcomes. The EMP may wish to review the content of the example SEMP. 5 This may not necessarily significantly affect environmental outcomes but it is inconsistent with the stated intentions of the project documents. Hurunui Windfarm - EMP Assessment 8 April 2011

8 5.0 The CEMP and EMP The CEMP is construction orientated and presents a very useful outline of the proposed construction approach. Various options, such as roading options, are discussed. The EMP is appended to the CEMP and focuses on the environmental outcomes of the project. However both need to be considered together to gain a full appreciation of the overall intent of the project. Section 7 of the CEMP tables a list of potential effects and discusses measures to mitigate these effects. The following table summarises these effects and whether they have been addressed by the EMP. Table: Identified Effects Potential Effect Significant areas of vegetation Site stability of roads and platforms Site stability of fill sites Seismic risk Discharges to air & water Sediment discharge to the Cave & Motunau catchments Flooding by culverts Effects of stormwater Mitigation Measure Construction activities will occur outside identified areas except in two areas (p17, CEMP) where the best compromise is proposed. The SEMP process refers to consideration of key environmental considerations, and loss of vegetation is identified as an issue in the EMP's Preliminary Environmental Effects Register. SEMP2 refers to a specific area of ecological value. This may be more of a construction issue and is addressed extensively in Section 5 of the CEMP. Particular areas are to be avoided and site specific final design is proposed The EMP has only a general reference to this (p14). Addressed by the CEMP (p29-30). The proposed SEMPs for specific areas will also address this issue. t specifically addressed by the EMP. Addressed by the CEMP (p47-48). t addressed by the EMP The EMP describes a number of erosion and sediment control measures. Rehabilitation and revegetation are discussed. SEMPs are proposed to cover site and location specific activities. A specific SEMP is proposed to address the implications of an on-site concrete batching plant if utilised. The Preliminary Environmental Effects Register identifies sediment and contaminant discharges Discussed in the CEMP. The example SEMP shows control measures for part of this area (but the measures are not considered to be tailored to any particular receiving environment values). Neither the EMP nor the example SEMP (which is in the Motunau catchment) makes specific reference to these catchments. Secondary flow paths are to be provided or design to accommodate the 100 year storm event is proposed (p44-45 CEMP). specific reference to this in the EMP. Procedures and measures to afford permanent control at discharge points are proposed (p43-44 CEMP). t specifically addressed by the EMP. Addressed by EMP? Yes/ Yes Indirectly Yes Hurunui Windfarm - EMP Assessment 8 April 2011

9 Visual effects Local traffic effects Dust & noise The CEMP addresses this to some extent but also acknowledges that visible cuttings, soil disturbance and vegetation clearance will result. Briefly discussed in the Preliminary Environmental Effects Register of the EMP. Sympathetic design and revegetation is proposed (p27). ^^ Proposed to be reduced by perhaps utilising on-site rock material and by an on-site concrete batching plant. The EMP does not address this except in relation to tracked mud (p31 & 37) A noise management plan is proposed (p51 CEMP). particular dust emission controls are specified in the CEMP. The EMP discusses dust control (p27). ise control (p28) is discussed in relation to NZ ise Standard NZS 6803:1999 Acoustics - Construction ise. Yes Yes Although the EMP does not address all of the potential effects identified in the CEMP, some of the effects e.g. geotechnical, appear to be appropriately addressed through the construction methodology in the CEMP. Further reference by the EMP may not be necessary. As a further comment of the linkage of the EMP to other documents, it is noted that the EMP does not directly address the AEE's comments on the relative vulnerability of the headwaters of particular catchments to the effects of sediment. This has been discussed earlier with the suggestion that the EMP establish processes by which to include consideration of such matters when developing specific environmental control procedures and measures. 6.0 Conclusions The EMP is a master plan to identify processes and techniques to achieve effective environmental management. It is linked to the CEMP which addresses the construction orientated aspects of the project. Some of the construction methodologies also address environmental objectives. The EMP covers a large range of activities in a succinct manner. One of the key initiatives proposed by the EM is the preparation of SEMPs. These are proposed to ensure that an appropriate level of environmental management is applied. They are to be location or activity specific. The concept of this approach is supported although some reservations are held over some aspects of their preparation and application. A significant focus of the EMP is on erosion and sediment control and the document presents a number of measures proposed for common usage. Some of these are considered to be reflective of best practice while perhaps others are not so representative. The EMP does not establish a process by which regard can be had to matters such as soil type, sediment yield risk, particular environmental values, staging and season of works etc when considering the appropriateness of particular control measure(s). One of the erosion and sediment control conclusions from the review is that EMP does not propose particular control strategies to address particular issues, but instead appears to propose controls that will apply across the project. Hurunui Windfarm - EMP Assessment 8 April 2011

10 10 Overall it is considered that the EMP establishes a process by which SEMPs are to be used to achieve environmental outcomes. This approach is supported. It is considered that the EMP could be reviewed to better reflect best practice erosion and sediment control measures, and that more specific processes could be established by the EMP by which to guide the preparation and standard of the SEMPs. fl Brian Handyside Hurunui Windfarm - EMP Assessment 8 April 2011

11 11 EROSION MANAGEMENT EROSION MANAGEMENT LTD, 35 HASTINGS PARADE, P.O. BOX , DEVONPQRT, AUCKLAND. NEW ZEALAND TEL, FAX; ATTACHMENT 1 Reviewer Details Brian Handyside has been involved in soil and water conservation in one way or another for over 30 years. For the past 23 years he has worked specifically in the erosion and sediment control side of construction. Originally he was employed by the Auckland Regional Council (now Auckland Council), and then in 1994 he formed his own specialist erosion and sediment control consultancy company. During the intervening period, he has prepared many erosion and sediment control plans on all manner of earthwork sites, been involved in the writing and preparation of a number of technical publications, and has ran many erosion and sediment control training courses for consultants and contractors. He is a co-author of the ECan 2007 erosion and sediment control guideline, and co-facilitator of a number of ECan erosion and sediment training courses. Hurunui Windfarm - EMP Assessment 8 Aphl 2011