A Guide to Hydro Power Construction: Good Practice Brochure

A JOINT PUBLICATION BYHYDRO POWER CONSTRUCTIONA GUIDE TOGOOD PRACTICEVersion 1, March 20121 INTRODUCTION 3 1.2 USING THIS GUIDE 3 1.3 KEY STAGES IN THE CONSTRUCTION OF A HYDROPOWER SCHEME 42 GENERAL PRE-CONSTRUCTION CONSIDERATIONS 43 TIMING OF WORKS 5 3.1 KEY CONSIDERATIONS 5 3.1.1 WEATHER 5 3.1.2 REQUIREMENTS OF WILDLIFE. 5 3.1.3 RIVERBED DISTURBANCE 54 CONSTRUCTION-PHASE METHOD STATEMENTS 6 4.1 KEY CONSIDERATIONS 65 CONSTRUCTION DRAINAGE 7 5.1 INDIRECT IMPACTS ON THE WATER ENVIRONMENT 7 5.1.1 EXCAVATION AREAS 7 5.1.2 PEAT MANAGEMENT 7 5.1.3 PRE-EARTHWORKS DRAINAGE 8 5.1.4 ACCESS ROAD, PIPELINE CONSTRUCTION AND CABLE TRENCHING 8 5.1.5 PERMANENT TRACK DRAINAGE 8 5.1.6 PUMPING 8 5.1.7 SITE COMPOUND 8 5.1.8 OIL STORAGE 9 5.1.9 REINSTATEMENT 9 5.2 DIRECT IMPACTS ON THE WATER ENVIRONMENT 9 5.2.1 INTAKES, OUTFALLS AND IMPOUNDING WORKS 9 5.2.2 ISOLATING WORKING AREAS 10 5.2.3 WATERCOURSE CROSSINGS 10 5.2.4 AUTHORISATIONS 10 5.3 MAINTENANCE 106 WOODLAND REMOVAL 11 6.1 FELLING REQUIREMENTS 11 6.2 POTENTIAL IMPACTS 117 RECREATION AND ACCESS 128 FURTHER INFORMATION AND CONTACTS 12CONTENTSHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICEHydropower scheme development in Scotland is accelerating rapidly. The Scottish Government, Scottish Natural Heritage (SNH) and the Scottish Environment Protection Agency (SEPA) support the development of renewable energy, including hydropower, as a key means of tackling climate change. The development of such schemes will require authorisation under the Water Environment (Controlled Activities) (Scotland) Regulations 2011 (CAR) and will also require planning permission under the Town and Country Planning (Scotland) Act 1997, or the Electricity Works (Environmental Impact Assessment) (Scotland) Regulations 2000 if the installed capacity is greater than 50MW. Without satisfactory measures, the water environment and surrounding habitats can become polluted as rainfall picks up and deposits dirt and silt. If they settle in the water environment they can prevent sunlight from reaching aquatic plants, and if sunlight can’t reach the plants, they perish. These sediments can clog fish gills and smother organisms inhabiting the river bed.Serious environmental harm can be attributed to pollution incidents from construction sites, through localised oil spills, concrete pouring and cement washout bays etc. Should such incidents occur, all measures should be taken to control the incident and prevent further runoff as soon as practicable, and SEPA and affected water users must be contacted.There may also be implications through the Waste Management Licensing (Scotland) Regulations 2011, not least through the movement and disposal of peat or forestry waste, depending upon the nature of the site. For projects involving the excavation of peat, or felling to waste in forestry areas, it is likely that the planning permission will refer to a peat management plan or waste management plan which will need to be complied with. All appropriate waste licences or exemptions if required must be in place before operations begin. The approach should be to minimise excavation of peat during the construction. Similarly, sensitive wetlands identified through the planning process should be avoided and protected during construction. 1.2 USING THIS GUIDEPlenty of guidance on pollution prevention measures already exists, and this guide does not seek to repeat these publications. This guide has been developed to direct the construction industry to the appropriate sections of the existing guidance. A list of the existing guidance has been provided in Section 8.1. INTRODUCTIONHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 3Familiarise with Licence and ConsentEnsure all staff are aware of the consent conditions Appoint Ecological Clerk of Works (ECW) where appropriateDevelop a CMS which is specific to the site Ensure SEPA, SNH and contractors agree with the CMSPlan the timing of construction workConsider seasonal issues e.g. spawning timesPrepare emergency response plansRefer to Environmental Statement and complete pre-construction surveys where appropriateInstall pre-construction drainage for area being developedClearly mark out any sensitive areas which are to be avoided during constructionProceed in accordance with CMSSupport ECW with monitoring and reporting requirementsReview progress against CMSStop and review if problems arise. Consult SEPA and SNHEnsure all staff are aware of restoration requirmentsEnsure restoration work is satisfactory before signing offDevelop a tailored Construction Method Statement (CMS)Section 4Plan the Pre-construction PhaseSection 3 and 5Consider any Pre-Costruction SurveysPrepare the Site DrainageSection 5Construct the SchemeRestore the Working AreasSection 5.1.81.3 KEY STAGES IN THE CONSTRUCTION OF A HYDROPOWER SCHEMEMost of the problems which arise during the construction phase of developments – discharge of silty run-off, oil etc. - can be avoided by getting to know the site e.g. by identifying drainage paths, downstream users and areas where flows would normally collect and discharge, and being proactive in forming a construction strategy.Getting pre-construction right will minimise pollution of the environment, harm to human health and unnecessary damage to nature conservation interests. It will also reduce risk, cost and delay, and increase stakeholder confidence in the project.Details of the issues to consider at this stage can be found on pages 9-11 of SEPA’s Good Practice Guide: Construction Methods. It is essential that staff are aware of the requirements of the relevant CAR water use licence, and that a copy of the licence is readily available on site for consultation.2. GENERAL PRE-CONSTRUCTION CONSIDERATIONSHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 43.1.1 WEATHERSince the winter months are generally wetter, there will be additional challenges in terms of managing run off and storm events. Snow and ice cover will restrict access and increase risks on site. Failure to adequately plan for flood events can result in considerable damage on site, construction delays and pollution of the water environment. Drainage issues are discussed in Section 5. Extended periods of dry weather can make it difficult to manage dust from vehicles and tracks, and vehicle movements may be constrained. In these instances suitable mitigation such as water sprays should be installed. 3.1.2 REQUIREMENTS OF WILDLIFEProtected species such as badgers, red squirrels, otters and bats are more active at different times of year and may require consideration. Information on this can be found at the SNH website. Particular care should be taken during the salmonid spawning and incubation period (Oct-May). The presence of other species such as lamprey may require consideration at other times of year. Guidance is provided in pages 10-13 of the Forests and Water Guidelines and in the SNH Guidance for Competent Authorities. Further advice on the appropriate timing of work can be obtained from the local SEPA and SNH offices. The relevant planning permission will refer to the permitted timings of work and must be complied with.3.1.3 RIVERBED DISTURBANCEAny work undertaken in or near a watercourse should be carried out at times of low flow and outwith spawning periods, with appropriate protective measures to minimise the opportunity for sedimentation.3. TIMING OF WORKSThe time of year and scheduling of construction must be taken into consideration in order to minimise impacts on the surrounding environment. The current turbine supply market and the availability of specialist contractors will limit the opportunities for a developer to fundamentally alter a construction schedule. Nonetheless, an awareness of the different issues likely to arise at different times of year will be beneficial, particularly in the context of planning for drainage and the impact of flooding events. 3.1 KEY CONSIDERATIONSHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 5The use of Construction-phase Method Statements (CMS) to guide a development is common practice across the construction industry, and is very helpful to ensure consistency across a project and make everyone aware of their responsibilities. It should prove that the risks to the water environment from the construction of the scheme have been identified and mitigated against. All staff must be made aware of the CMS and carry out activities in accordance with it.4. CONSTRUCTION-PHASE METHOD STATEMENTS• Has the order of work been clearly laid out?• Have the risks of pollution to the water environment been identified?• Have the appropriate pollution-prevention measures been put in place?• Are staff aware of their responsibilities in terms of monitoring and maintaining these measures?• Do staff know who to approach with any on-site pollution issues?• Have all drainage, waste management, ecological aspects, habitat management, and noise and dust generation issues been considered and addressed?• Do the CMS timings match ‘work on the ground’ timings?• Are all aims, procedures and details within the CMS achievable?• Is the CMS available on site and referred to on a daily basis?4.1 KEY CONSIDERATIONSThe CMS must be specific to the site and able to answer the following questions in plain, easy to understand language.The CMS must be able to answer these questions, and the on-site activities must reflect the CMS. If they do not, the activities could breach granted planning permission and CAR water use licence conditions. The local SEPA office should be contacted for further advice on the content of the CMS or if any alterations are proposed.HYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 6It is essential that the potential for sediment release is minimised throughout the construction phase. This should be addressed both through suitable construction practices and drainage, and through appropriate training and monitoring. SEPA’s Good Practice Guide: Construction Methods provides more details on this. Refer specifically to pages 14-23, 29 and 33-37. Some general information is supplied below:5. CONSTRUCTION DRAINAGE• Install the drainage and mitigation measures appropriate for the area being worked. This must be in place before any construction work commences in that area;• Treat all surface water from construction sites via sustainable urban drainage systems (SUDS). The appropriate CIRIA manuals (The SUDS Manual, Control of Water Pollution from Construction Sites, and Control of Water Pollution from Linear Construction Sites) should be consulted, and it is advisable that the local SEPA office is contacted for advice. Chapter 5 of the SUDS manual provides further guidance on the selection of the best treatmentsystem;• Keep clean water flows clean, by not allowing them to mix with “construction” drainage. Page 16 of Good Practice Guide: Construction Methods describes this in more detail;• Do not allow direct ditch discharge into watercourses, lochs or sensitive wetlands. This is a requirement of General Binding Rules 10 of CAR;• Minimise any effects on natural flora and fauna to ensure there are no impacts on any surrounding designated sites or sensitive habitats;• Progress works efficiently. Ensure flash wash-out events will not affect partially completed sections.5.1.1 EXCAVATION AREASExcavation activities are the primary source of sedimentation during the construction phase of works. Due to the common steep inclines and proximity to the water environment, the effective drainage of hydro sites can be a challenge; however, it must be installed prior to the commencement of works. This section highlights the major phases of works which would require excavation and therefore appropriate drainage.5.1.2 PEAT MANAGEMENTSurplus peat management can be a key consideration of the construction phase. The joint SEPA and Scottish Renewables paper ‘Guidance on the assessment of peat volumes, reuse of excavated peat and the minimisation of waste’ is available on the Scottish Renewables website. It has been created in order to provide clear guidance of the waste issues that can arise during developments on peat, and how these should be dealt with within the hierarchical requirements of the Waste Management Licensing (Scotland) Regulations 2011.If there are any specific waste minimisation queries, contact your local SEPA office.5.1 INDIRECT IMPACTS ON THE WATER ENVIRONMENTHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 75.1.3 PRE-EARTHWORKS DRAINAGEThis is the term generally given to cut-off/diversion ditches that are installed ahead of the main earthworks activities to minimise the effects of collected water on the stripped/exposed soils once earthworks commence. The purpose of these drainage ditches is to intercept any surface run-off and direct it to the existing low points in the ground for collection, allowing clean water flows to be transferred through the works without mixing with the “construction” drainage. They should be installed on the “high-side” boundary of the areas that will be affected by the earthworks operations, and should be installed immediately ahead of the construction operations commencing. They should generally follow the natural flow of the ground with a shallow longitudinal gradient. Pages 14-20 of SEPA’s Good Practice Guide: Construction Methods provide useful information on their design and construction.5.1.4 ACCESS ROAD, PIPELINE CONSTRUCTION AND CABLE TRENCHINGWhere a hydro scheme is proposed in an upland area, the SNH publication ‘Constructed Tracks in the Scottish Uplands’ and the floating road guidance ‘FCE / SNH Floating Roads on Peat’ should be consulted in addition to the drainage section of this guidance. The Forestry Commission’s Forests and Water Guidelines should be consulted when considering the access road to the construction site.5.1.5 PERMANENT TRACK DRAINAGEAppropriate measures (through the use of track edge drainage, side ditches and pipes etc.) are required to remove surface water emanating from this area. Appropriate SUDS should be incorporated to reduce run-off rate and improve water quality. Refer to the SUDS manual or the local SEPA office for specific advice.5.1.6 PUMPINGWhere there is a significant build up of water in the construction area it may be required to pump this to avoid further build up, or to allow works to progress in that area. Pages 31-38 of SEPA’s Good Practice Guide: Construction Methods provides further details on this. The disposal of the pumped water must comply with General Binding Rules 10 and 11 of CAR, and should not be to peatland areas. Some acceptable methods of disposal are described in pages 39-43 of SEPA’s Good Practice Guide: Construction Methods.5.1.7 SITE COMPOUNDMost hydro developments require a site compound during the construction stage of the project. This section provides details on best practice for design considerations and construction methods including possible environmental mitigation methods. Drainage from the site compound should be appropriately designed in accordance with General Binding Rules 10 and 11 of CAR. The site facilities will include mess and toilet facilities for the site workers. The design of the effluent system will depend on the sensitivity of the adjacent area. Where soakaways are proposed they should be kept as far away from watercourses as feasibly possible. SEPA authorisations may be required and the local SEPA office should be contacted for advice as early as possible.Note that any local abstractions of water for use in the compound should comply with GBR2 if less than 10m3 per day. If greater than this volume, a CAR registration or licence will be required.HYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 85.1.8 OIL STORAGENormally bulk fuel and oil storage will be within the site compound area. Suitable bunded areas should be designed and constructed to meet the requirements of SEPA’s pollution prevention guidelines and the Water Environment (Oil Storage) (Scotland) Regulations 2006. Advice on appropriate storage is available on pages 8 and 9 of Pollution Prevention Guidelines 5: Works and Maintenance in or near Water.5.1.9 REINSTATEMENTReinstatement of the construction area should be carefully planned prior to any works taking place. Chapter 14 (pages 50-52) of the Good Practice During Windfarm Construction Guidance describes potential issues in more detail although some points for consideration have been provided here. The reinstatement could include a degree of landscaping followed by replacement of the topsoil over the area. Careful consideration of the site specific conditions is required to ensure successful regeneration. All reinstatement should be carried out in accordance with the relevant conditions of the associated planning consent. Suitable material for reinstatement should be appropriately stored and managed, near to the site compound but away from/with suitable buffers from watercourses and other sensitive receptors. The management and restoration of habitats impacted by a hydropower development is often required. This may be to prevent and/or minimise impacts on sensitive habitats (or species dependent on a certain habitat) during the construction and operational phases of the hydro scheme. Developers may also be required to implement restoration measures for certain habitats as compensation for damage, or to improve the overall carbon balance of the development.The design and construction of the impounding works, headrace and tailrace all require works in or near to the water environment and as such have the potential of causing significant adverse impact. Pages 28-34 of SEPA’s Good Practice Guide: Intakes and Outfalls provides the appropriate advice on the issues to be considered when designing your headrace and tailrace. It will be a condition of the associated water use licence that the structures are built in accordance with the design drawings. Failing to build in accordance with the designs would constitute a breach of the CAR water use licence and could result in the structure having to be removed, which would incur significant expense and delay. It is therefore vital that the final plans are accurately followed. Should the designs have to be changed during construction the appropriate regulating body must be contacted.5.2 DIRECT IMPACTS ON THE WATER ENVIRONMENT5.2.1 INTAKES, OUTFALLS AND IMPOUNDING WORKSHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 95.2.2 ISOLATING WORKING AREASIt is usually necessary to isolate working areas during the construction of these engineering structures. For details of the measures to be taken to minimise impacts, pages 20-40 of SEPA’s Good Practice Guide: Temporary Construction Methods should be consulted.5.2.3 WATERCOURSE CROSSINGSThe location of watercourses should be given careful consideration in determining the routing of roads and pipelines and the location of both temporary and permanent infrastructure. The crossing of watercourses should be avoided where possible. Where these do prove a necessity, pages 43-50 of Good Practice Guide: Temporary Construction Methods provides the appropriate advice. In such instances, it would be useful to provide an appropriate spill kit.5.2.4 AUTHORISATIONSAll watercourse crossings must be carried out in accordance with CAR. Authorisations range from general binding rules through to complex licences. Further information should be sought from SEPA. Different timescales apply for each level of authorisation, and these timescales require to be allowed for in the overall construction planning. Pages 43 - 53 of SEPA’s Good Practice Guide: Temporary Construction Methods provides more details.Designing and installing all drainage requirements is essential, but appropriate monitoring and maintenance is equally important. The following points should be considered:• Properly plan and map silt mitigation for the site. Number all the different treatment areas on the site e.g. silt pond 1 (SP1), drainage ditch 2 (DD2) etc. This will prove useful when inspect-ing, recording and informing staff of prob-lem areas;• Record details of the weather, inspections and maintenance carried out etc;• Monitor and maintain all ditches, ponds, pipes, silt fences etc. on a regular basis. Monitoring should be carried out in accordance with the weather conditions – for example, more fre-quent inspections should be carried out during and after periods of heavy rainfall;• Check the watercourse(s) downstream of the construction area for signs of discolouration, sediment build up etc;• Any permanent settlement lagoons should be checked for leakage and, following periods of heavy rainfall, if there has been sufficient settling of sediments, water levels should be lowered to allow increased containment capac-ity to be available within the lagoon for the next rainfall period; • Any ditches should be checked for blockages, and kept clear and in good order. Any growing vegetation in ditches should be left as this will aid in the filtering of some of the sediments.5.3 MAINTENANCEHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 106. WOODLAND REMOVALThe removal of trees during the construction phase may be required for a number of reasons, including:• Along proposed track routes and other construction areas; and• within and around the area of the site compound or lay-down areas to allow for subsequent open-ground habitat restoration that may form part of compensatory works as a consequence of other actions arising from the development.6.1 FELLING REQUIREMENTS6.2 POTENTIAL IMPACTSAny tree felling carried out without a felling licence or other valid permission is an offence unless it is covered by an exemption. Prior to undertaking tree felling it is therefore essential to check that the area to be felled has either been formally consented through the development management process or through a felling licence issued by Forestry Commission Scotland. All forest operations should comply with the requirements of the latest version of the UK Forestry Standard and associated Guidelines.Staff associated with the works should be made aware of any sensitive habitats and protected species associated with trees proposed for felling, for impacts such as disturbance, habitat loss or direct mortality. Local area SNH should be contacted prior to woodland removal activities if habitats and species are likely to be impacted, and the local SEPA office should be contacted to discuss potential waste management licensing requirements.Woodland removal operations should not increase the likelihood of run-off or slope instability issues, and disturbance (including spreading of chips or excavator movements) of areas of vegetation within or adjacent to the forest should be avoided unless absolutely necessary. Mulching of significant amounts of forestry waste is unlikely to benefit from a waste exemption, and the local SEPA office can provide advice on this.HYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 11• How will access be managed during the construction process? (eg. route sign-posting, alternative paths, training for vehicle drivers, provision of refuge passing places)• Use site phasing, to ensure that exemption from access rights due to building and engineering works is kept to a minimum area, only where works are active• Information provision, including Health and Safety information (eg. signs and way-marks, leaflets, information boards, relevant websites, contacts with representative groups, community newsletter)• Will particular phases or aspects of the construction be problematic? (e.g. creating temporary cul-de-sacs). If so, can suitable alternative routes be provided, indicated and explained?• Are there particular risks during construction (e.g. blind corners on tracks, unstable ground) that users and construction workers need to be made aware of?7. RECREATION AND ACCESSKey considerations during the construction phase:8. FURTHER INFORMATION AND CONTACTSCAR Practical Guidewww.sepa.org.uk/water/water_publications.aspxSalmon and Freshwater Fisheries Act (2005)www.opsi.gov.uk/legislation/scotland/ssi2005/20050174.htmCIRIA Publications - available from the CIRIA website, www.ciria.orgControl of Water Pollution from Construction Sites – Guide to Good Practice (SP156);Control of Water Pollution from Construction Sites – Guidance for Consultants and Contractors (C532);Control of Pollution from Linear Construction Projects – Technical Guidance (C648);Control of Pollution from Linear Construction Projects – Site Guide (C649);Environmental Good Practice – Site Guide (C650);The SUDS Manual (C697);Site Handbook for the Construction of SUDS.Pollution Prevention Guidelines relevant to construction www.netregs.gov.uk/netregs/links/63901.aspxPollution Prevention Guideline (PPG) 5: Works and Maintenance In or Near Waterwww.sepa.org.uk/about_us/publications/guidance/ppgs.aspxPollution Prevention Guideline (PPG) 6: Working at Construction and Demolition Siteswww.sepa.org.uk/about_us/publications/guidance/ppgs.aspxPollution Prevention Guideline (PPG) 21: Pollution Incident Response Planningwww.sepa.org.uk/about_us/publications/guidance/ppgs.aspxHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 12Position Statement: Sediment Managementwww.sepa.org.uk/water/water_regulation/guidance/engineering.aspxGood Practice Guide - River Crossingswww.sepa.org.uk/water/water_regulation/guidance/engineering.aspxGood Practice Guide - Intakes and Outfallswww.sepa.org.uk/water/water_regulation/guidance/engineering.aspxGood Practice Guide: Construction Methodswww.sepa.org.uk/water/water_regulation/guidance/engineering.aspxSNH Hydroelectric Schemes and the Natural Heritagewww.snh.gov.uk/docs/C278964.pdfFCE / SNH Floating Roads on Peat www.roadex.org/index.php/services/partner-knowledge-bank/scotland/floating-roads-on-peat-reportSNH Constructed Tracks in the Scottish Uplands www.snh.gov.uk/publications-data-and-research/publications/search-the-catalogue/publication-detail/?id=513Forests and Water Guidelines (4th Edition) www.forestry.gov.uk/pdf/FCGL002.pdf/$FILE/FCGL002.pdfGood practice during Windfarm Constructionwww.snh.gov.uk/planning-and-development/renewable-energy/onshore-wind/good-practice-during-windfarm-const/Bats www.snh.gov.uk/about-scotlands-nature/species/mammals/land-mammals/bats/Guidance on the assessment of peat volumes, reuse of excavated peat and the minimisation of wastewww.scottishrenewables.com/publications/guidance-assessment-peat-volumes-reuse-excavated/CONTACTSScottish Natural Heritage (SNH)www.snh.gov.uk/contact-us/how-to-contact-us/offices/Scottish Environment Protection Agency (SEPA)www.sepa.org.uk/about_us/contacting_sepa.aspxHYDRO POWER CONSTRUCTION GUIDE GOOD PRACTICE 13