Goedwig Hydro construction method statement: 22/04/2016 Prepared by Goedwig Hydro Limited This is the method statement for construction for the Afon Goedwig micro-hydro power project. The civil engineering components of the project are; an intake weir, penstock pipe, powerhouse and outfall. This method statement includes precautions for in and out of river works with respect to protection of watercourses and aquatic life. These construction methods precautions and mitigation draw on guidance contained in the SEPA document; Engineering in the Water Environment Good Practice Guide: Temporary Construction Methods (Document reference: WAT-SG-29) and Works in, Near or Liable to Affect Watercourses: PPG5. The following sections detail the outline of works for each component of the project, followed by the matrix of key hazards with respect to protection of watercourses on site and the incident response procedure Construction Schedule Intake construction is planned May-June, historically the driest months for this area. Plans will be reactive to weather conditions. Works in rivers will be only be carried out in period of low flow and concrete pouring will only be carried out in a stable period of dry weather. In event of adverse weather predictions all at risk or dismountable works will be removed from the river and the banks. Pipe installation planned June-July and powerhouse July-August. Plans will be reactive to weather conditions. Works on steep ground and pipe burial will be carried out in suitable weather and ground conditions. Overall sequence of works 1 Site Preparation: 1.1 Necessary drawings and documentation are in place for the works. 1.2 Health and safety documentation and provision is in place. Action plans and materials in place to respond to any incidents involving leaks/breaches/spillages. 1.3 Induction of all contractors on arrival at site including; access, incident and emergency procedures, health and safety, environmental protection, and pollution control 1.4 Access routes are established and “no go” zones are marked out

2 Intake Construction: The intake will be formed in a sequence to maintain the unimpeded flow of the stream during construction. A silt trap will be established out of the river. Temporary coffer-dams will be constructed to divert the flow during formwork and initial casting of the weir. A bypass capable of carrying the seasonal flow will be cast into the first half of the weir. See subsequent steps for detailing of these processes. Diversion of flow during in river works: The weir will be constructed in two stages, see plan below for layout. Installation of a 500mm high cofferdam using sandbags and waterproof liner (marked “stage 1 cofferdam” below) will allow for complete de-watering of south side of river for construction of first section of the weir. Sandbags, straw bales and silt fence materials will be used to isolate the area of in river works and capture any leaks or spills from the construction. A pump will be on hand to remove any silt-contaminated water from drained down areas and divert it to the previously established out-of-river silt trap. The first section of the weir will be cast with a large open bypass notch. Once the construction of the first half of the weir is complete (see below for sequence of works) the stage one cofferdam will be demounted. The stage 2 cofferdam will be constructed to divert the flow of the river through the oversized bypass notch in the cast section of the weir. The area behind the stage 2 cofferdam will be fully drained down with the assistance of a pump, which will discharge into the out-of-river silt trap. Once the area of works is satisfactorily isolated and drained down, construction can commence on the second half of the weir. Once all casting work is completed on the weir and all temporary in river works have been removed, a pre-fabricated plate will be slotted into place in the bypass notch to complete the weir. Management of silt from dewatered areas; A silt trap will be set up on a gently inclined area at minimum 10m from the river. Geotextile silt fences will be erected across the drainage lines to intercept all of the flow from the designated area of the silt trap. Once work areas within the watercourse have been isolated by construction of a temporary cofferdam, a pump will be installed to remove water from the work area. Pumped water will be discharged in the silt trap. The function of the silt trap will be closely monitored and continuation of works will be conditional upon the correct functioning and adequate capacity of the silt trap.

Management of cement mixing and washing areas; All contractors and deliveries of concrete will be required to reduce to a minimum the necessity for onsite washing of plant and tools. A sealed container will be set up on the far side of the forestry track, more than 10m from the watercourse, for washing tools or parts of plant contaminated with cementitious materials. On completion of works the inactivated liquids and solids will be removed and disposed of away from the watercourse. Supervision of works, response to silt and spillages and additional materials; A construction manager will be on site at all times during the operation of in river works. The manager will monitor the integrity of the pollution prevention measures. The project manager will have responsibility for communicating to all contractors their requirements with respect to protection of local environment and watercourses, and for implementing the response to any pollution incidents – see section 6 below. There will be a supply of materials on site to respond quickly and prevent contamination of the watercourse by silt and spillages. Straw bales and geotextile silt fence fabric will be available on site to erect additional silt traps as required. A spill kit will be available on site for the containment of oil leaks. Sequence of intake works; 2.1 Establish out of river silt trap to take discharge from any pumping and separate out of river washing area for any concrete-contaminated tools and plant. 2.2 Establish temporary diversion of flow within watercourse and pollution/sediment control measures: Make temporary water diversion to allow in channel work at the site of the intake structure. Check structure before carrying out works and throughout duration of works. 2.3 Ensure isolation of any areas drained for work within the river channel and any other potential drainages into the river which are identified as at risk of carrying pollution from the construction or associated processes eg. movement of plant or temporary storage of materials. Extra materials for additional containment of silt and spillages will be kept on site to allow reactive measures to be taken. 2.4 Intake construction: Remove overburden to base rock, work will be carried out with hand tools and excavator as required. Careful monitoring will be made of precautions taken to ensure surface material does not enter into the watercourse. Any excavated material is to be stored well away from watercourse. 2.5 Preparation for concrete pour; fix rock anchors, construct and seal formwork, install valves and fittings, install steel reinforcement 2.6 Before any concrete is poured check integrity that formwork is fully sealed. Once all preparations are checked and found to be good and conditions are suitable pour concrete and compact using vibrating poker 2.7 Strike formwork once the concrete has cured. Fix fixtures and fittings and

intake screens 2.8 Repeat processes as necessary to complete works 2.9 Demount silt traps/pollution control measures 3.0 Tidy site on conclusion 3.1 Monitor new structures and reinstated grounds for any potential issues, this will be close monitoring for the first months as the construction and commissioning of the project continues, then regular monitoring once normal operation and maintenance of the scheme is established. 3 Pipe installation: Pipe handling and welding The pipe will be installed by welding 12m sections of Polyethylene pipes into longer strings, which will then be winched into location. The works associated with the movement of pipe sections and welding equipment will be carried out on the existing hard standing forestry tracks away from watercourses. Pollution control Open cut trenches will be fitted with silt traps at all downstream egress points and intersections with culverts or other drainage lines to prevent contamination of watercourses. The operation of these measures will be monitored by the construction manager, who will halt works and implement any further pollution control measures as required. Temporary storage of excavated materials will be away from watercourses and drainage lines. Silt fences will be erected below stored materials as necessary to prevent run-off of silt. Access to the site is by existing forestry tracks. We will minimize requirements for vehicles to leave existing tracks. Where vehicle access off of the tracks is required silt traps will be installed on any drainage lines and wet flushes crossed by the access routes, Pipe route and burial The pipe route is adjacent to the forestry track for the upper 400m. Depth of cover over the pipe adjacent to the road will be minimum 1000mm. The pipe will be buried in the verge adjacent to the forestry track. Excavated spoil will be temporarily stored on the side of the track. Once the pipe has been welded and installed it will be backfilled using the excavated spoil. Where our route crosses existing culverts the location and level of the pipe will be set so as not to interfere with flow through the culvert, nor impede future access to the culvert for maintenance or replacement.

The section of pipe exiting the intake the pipe runs in the riparian zone and precautions will be taken as for the construction of the intake with respect to pollution and silt control. After 400m meters the pipe route leaves the forestry road. Where the route is not accessible from existing tracks it will be hand laid and covered. Where the pipe runs under the public footpath it will be buried to a minimum cover of 400mm. The route of the pipe will be clearly marked with pipe markers supplied by NRW. The procedure of works for pipe installation will be as follows; 3.1 Silt traps are installed on any active drainage lines that are crossed by the pipe route 3.2 Temporary diversion of flow within watercourse using coffer-dam is carried out as required to enable connection of first section of pipe to intake chamber. 3.3 Excavation for pipe is carried out in appropriate conditions for the local ground condition and incline 3.4 Any excavated material is to be stored away from edge of watercourse and drainage lines 3.5 Open cut trenches are to be fitted with temporary silt control measures 3.6 Once pipe is installed consolidate backfill round pipe to exclude air and avoid water following the pipeline 3.7 Demount silt traps/pollution control measures 3.8 Tidy site on conclusion 3.9 Monitor new structures and reinstated grounds 4 Powerhouse and outfall construction: Construction of the powerhouse will consist of a concrete foundation and floor slab, block-work walls with timber cladding and turf roof. Precautions will be taken for avoidance of pollution and silt contamination as per the intake construction. Particular care will be taken to fully briefing contractors on site requirements with respect to protection of the watercourse; no washing of tools or plant in or adjacent to the watercourse or drainages, no movement of plant or materials into excluded zones established during site layout, careful disposal offsite of any surplus materials and waste. Management of silt from dewatered areas, cement washing, supervision and incident response; A silt trap for discharge of pumped water and a concrete washing area will be set up as per the intake. A construction manager will be on site at all times during works taking responsibility for informing and instructing subcontractors, monitoring of pollution control measures, and implementing response to any incident.

The outfall will be constructed in the following steps; 4.1 Works are isolated from the river by erection of a temporary cofferdam – see sketch plan below for layout. A small pump will be installed behind the cofferdam to drain down the area for work. Pumped water will be discharged into the silt trap erected away from the watercourse. 4.2 The outfall area is excavated down to bedrock or solid ground. Existing material to be placed to one side for reinstatement 4.3 The floor slab will be cast in concrete 4.4 Once cured, the main outfall structure will be shuttered and cast with reinforced concrete, around the pipe from the turbine. Wing walls will be completed, tied into the banks 4.5 River bed reinstated to original level 4.6 Bank and bed scour protection (gabions and/or boulders) will be completed 4.7 Outfall screens fitted 4.8 Demount coffer dam and pollution control measures 4.9 Tidy site on conclusion 4.10 Monitor new structures and reinstated grounds

5 Export cable duct installation: The export cable is ducted under the Afon Goedwig. The duct carrying the cable will be buried in the existing bed material at a minimum depth of 500mm below the existing bed level. The bed at the point of crossing is composed of large shale mudstone. Burial of the duct will be carried out only in very low flow conditions and in a sequence to maintain the unimpeded flow of the stream during construction. A temporary diversion will be constructed to divert the flow within the existing channel whilst the duct is being installed.

Sequence of works for duct installation is as follows; 5.1 Establish temporary diversion of flow within watercourse and pollution/sediment control measures 5.2 Any pumping required for dewatering of works will be discharged out of the river channel into silt traps 5.3 Remove material for burial of duct – all removed material is to be stored out of river and held separate from surrounding material for reinstatement 5.4 Install duct and replace bed material, ensuring reinstatement of bed and banks to original condition with additional stone as necessary 5.5 Remove temporary flow diversion and demount silt traps/pollution control measures 5.6 Tidy site on conclusion 5.7 Monitor reinstated grounds for any potential issues 6 Potential environmental hazards and mitigation measures The following lists primary environmental hazards identified and mitigation measures which will be put in place Hazard Mitigation 5.1 Silt making the water turbid and causing damage to aquatic plants and fish populations

Do not disturb submerged silt beds or material within the river. Do not allow any excavated material to enter into the river. Install silt traps on the drainage points of any areas drained and isolated for work within the river channel to prevent surface water carrying material into the river flow.

5.2 Cement entering the watercourse Pour cement used in in accordance with best practice. Clean tools and plant in appropriate sealed containers. Ensure that requirements for environmental protection and non-contamination of watercourses are clearly communicated to all contractors and drivers on site. Materials will be on site for entrapment of spillages.

5.3 Spilled / leaked vehicle fuel and hydraulic oil entering watercourses, affecting water quality and fish populations

If any diesel is required to be stored on site it should be stored in appropriate containers, bunded where necessary with ample capacity, away from watercourses Monitor construction vehicles for leaks and respond to any indication of leaks or risk. Only permit adequately maintained vehicles onto site

5.4 Oil and fuel contaminating soil If an incident occurs and any soils or other materials are contaminated with fuel or oil, move them to a suitable landfill site. Ensure that there is provision on site for containment of spills

5.5 Chemicals entering the watercourse

Consider necessity of any chemicals brought onto site, avoid use of all potentially harmful chemicals and substitute for non toxic materials and processes wherever possible. If necessary for use on site keep chemicals and oils securely stored. Ensure any contractors are aware of correct usage and importance of avoiding contamination through careless use, spillage or improper disposal.

5.6 Disturbance of fish populations at critical times of movement or spawning in river channel

We will carefully follow the conditions of our abstraction licence to limit extent and duration of works in river to avoid any disturbance to fish populations during sensitive periods

6 Incident Procedure In the event that the environmental protection measures should fail and an unforeseen pollution incident should occur, the following procedure is to be followed: 6.1 Discoverer of incident alerts Construction Manager of nature and magnitude of the incident 6.2 Construction Manager to reports incident to Natural Resources Wales immediately in order to inform of potential hazards and to take advice on how to proceed 6.3 Construction Manager and team to prevent situation from getting any worse (i.e. stop pollution source if possible) 6.4 If not possible to stop pollution source, Construction Manager and team to contain situation and minimize damage 6.5 Work not to be recommenced until pollution incident is resolved and all mitigation measures have been checked and reinstated 6.6 Following any incident; Construction Management team to review site methods and working practices with NRW