CF50/100 KW TURBINE ACCESS ROAD, CRANE PLATFORM, CONCRETE, AND LIFTING SPECIFICATIONS C&F GREEN ENERGY REVISION PREPARED BY APPROVED BY DATE 001 First Draft W Hession 12.02.2014
Introduction This document has been designed as a guideline which describes the minimum requirements for access roads, crane platforms and turbine foundations for the CF 50 CF 100 KW Wind Turbine. This document is also designed to be included in contractual agreements as a supplementary document to specify such minimum requirements and any deviation hereto. This document is not sufficient in and of itself to construct Access Roads, Crane Pads, Pad Foundations and Hardstands and must be supplemented for each project and site before construction work commences in order to ensure the specifications and the final choice of crane and transport equipment are aligned with the site requirements. The exact design of Access Roads, Crane Pads, Pad Foundations and Hardstands must be agreed with C&F Green Energy in writing prior to start of construction. Recipient acknowledges that this document is provided for recipient s information only, and that any and all promise, commitments, or other representations by C&F green energy are contained exclusively in signed written contracts between recipient and C&F green energy, and not within this document.
Abbreviations and Definitions Access Road(s) BS Refers to a road, existing or purpose-built, which leads from any public road system to the Site Entrance. Refers to British Standards. Bearing Capacity Factor of Safety CBR Ratio of ultimate bearing capacity to allowable bearing capacity to be determined by a C& F engineer. Refers to the California Bearing Ratio. This is a test to determine the ratio between the pressure required to penetrate the soil at the site and a standardized soil of known properties. Crane Pad Roads Site Refers to a hardstand area in connection with the erection or service of a wind turbine. Refers to any Access and/or Site Roads. Refers to all areas where the permanent works are to be executed and to which turbines and all associated equipment and materials are to be delivered, and any other areas that may be specified in the contract as forming part of the Site. C&F Turbine Summary: Weight of CF turbine head 12 ton Length of blades for turbine 10m/12m Weight of two turbine masts/towers bottom section 9 ton/ top section 7 ton Length of each turbine mast/tower bottom section 13.5 m/ top section 13.5m Weight of turbine can 2 ton Dimensions of base foundation to be excavated by client 11m x 11m x 1.8m Dimensions of concrete foundation 9m x 9m x 1.4m Approximately 18 cubes for the sub-base concrete pour, mix of C30/37 Approximately 120 cubes for the main concrete pour, mix of C32/40 Concrete pump required for main concrete pour. Excavator bucket shall not be used during main concrete pour Independent concrete tester required to sample and test main concrete mix onsite
Geotechnical Testing Each turbine excavation is required to have a geotechnical investigation carried out. The geotechnical report should incorporate the below points. Trial pit investigation (the trial pit investigation will establish if any additional testing is required) CBR or plate bearing tests on access road and crane hardstand PH and sulphate tests Groundwater monitoring standpipe (Geotechnical engineer to confirm) Clients Geotechnical report confirming the proposed site has adequate bearing capacity. The above photo is a typical trial pit investigation CBR test for access road carried out using a Land Rover
Plant required 3 ton teleporter: To unload the reinforcement and turbine can of C&F delivery truck, the teleporter is also required when tying the foundation reinforcement. 20 ton excavator with 18 inch bucket: To carry out the detailed excavation before the sub base pour and to lift the turbine can into place. Smaller excavators are not strong enough to lift the can into place. Concrete pump: Each site to be individually inspected to determine pump size. Common pump size used onsite are 24 meter pumps. Dewatering pump: To be used when excess water is in the excavation. The above photo shows a 20 ton excavator lifting the turbine can into place Typical concrete pump used onsite
Site Preparation Access Road The access road for the turbines has been designed with consideration for the trucks and cranes that will be used during the turbine installation. The below points and photos are a minimum requirement for each turbine, failure to follow the below points could lead to delays to the turbine foundation construction and turbine erection. Access road to be identified onsite with C&F engineer. Access roads are to be a minimum 5m across and 400mm depth. Access road material to be 100mm down or equivalent material approved by C&F engineer. Access road to be capped with clause 804. The road should be free from objects that can damage or puncture vehicles. Any gradient in excess of 8 degrees or narrow road width/entrances must be discussed with clients crane supplier. The road overhead clearance must be a minimum of 5 metres from the surface of the road. Geotechnical test (CBR) test carried out on several sections of the proposed access road. Clients Geotechnical engineer to confirm if geotextile membrane is required. Identified soft spots to be removed and built up in 200mm layers of 100mm down and vibrated with roller. Access road to be inspected by C&F engineer before commencement of turbine foundation Access road entrances from secondary roads to be adequate for 40 ft truck and mobile crane. After the turbine has been erected the access road and crane platform are to be retained for future maintenance works. In the event the access roads or crane platform are backfilled there could be delays and cost implications until the above mentioned have been restored.
The above photo shows the typical and correct access required for each turbine site. Incorrect material placed could prohibit crane and truck access. The above site had incorrect thickness of crushed rock and was capped off with soil. This delayed the crane erection by several days
Crane Pad The construction site for the CF 50-100 KW turbines has been designed with a crane pad to insure that the mobile cranes specified have adequate and safe lay down and working areas. Failure to follow the below points could lead to the delay the construction of the turbine foundation and further delay the turbine erection. The crane pad to be identified by C&F engineer and client onsite before any works commence. During this site investigation the orientation of the crane pad will be determined. Each crane pad to be constructed to the dimensions shown on the below sketch 1. Any deviations from these dimensions are to be communicated to C&F and signed off by C&F engineer. Geo testing (CBR or plate bearing tests) to be completed at random locations on the crane pad and the geotechnical engineer to confirm if the ground conditions are suitable for the specified crane. The crane pad drainage must be constructed to control the flow of surface water on, alongside and around the Crane Pads so as to self- drain. The crane pad is to be excavated to a minimum depth of 500mm to ensure no settlement of cranes and trucks during the construction and erection of the wind turbine. Once excavated 100mm down or approved equivalent material is to be installed in 250mm layers and rolled. Construction recycled material should not be used as hard-core fill unless the material is crushed and has been signed off by a C&F engineer. All imported material should be compacted and vibrated using a vibrating roller The crane hardstand should be free from objects that can damage or puncture vehicles. Provision must be made for the safe and proper lay-down and storage of parts in a suitable secure location. Parts include and are not limited to: lifting tools, service platforms, uninterruptible power supply, tower cables and work platforms.
Sketch 1: Site layout with dimensions Sketch 2: Crane and truck layout
Figure 1: Illustration of incorrect crane road and crane hard stand material
Wind Turbine Foundations C&F wind turbine foundations are constructed in several stages Stage 1: Main excavation C&F require an excavation of 11m square excavation before the can start to install the reinforcement and pour concrete. Centre of turbine must be established by the client/clients engineer The excavation required is to be 11m x 11m square, Once the excavation is complete an access ramp is to the excavation for people to walk into the excavation. Ramp location to be marked out onsite The operator shall excavate to a depth of 1.8m where the start of this excavation point will be determined by C&F engineer onsite prior to the excavation works. The site investigation carried out by the geotechnical engineer will establish if rock is present and at what depths. Excavated material to be removed approximately 30m from excavation to ensure know obstruction occurs onsite and edge of excavation dose not collapse. Where the soil is of a loose material and prone to collapsing the excavation is to be benched at 1mx1m around the entire excavation
Figure: example of 11m x 11m excavation Figure: illustration of excavation edge collapsing, in these site conditions the site should be benched
Stage 2: Sub base construction After the 11m x 11m excavation has been completed a detailed dig is required on the base of excavation. Please see the below photo showing the location of the detailed dig and the dimensions to be used. The first part of the detailed dig is in the centre of the excavation where the turbine can is located. The excavation is 3.1 x 3.1 x 400mm deep. The second part of the detailed dig is for the formwork, the dig is 400mm wide by 200mm deep slot that goes around the whole excavation. The centre of the slot is 9m square Once the detailed dig is complete C&F will install the turbine can hold down bolt along with reinforcement. Approximately 18m3 C30/37 is required for the sub base pour. Please see attached design mix No concrete pump or testers are required for this pour. Crane hardstand should be in place to allow adequate room for the concrete truck to turn and discharge.
Figure : Example of the completed dig and dimensions required. Figure : 18m3 of C30/37
Stage 3: Installing reinforcement, turbine can and formwork After the sub base concrete has cured C&F install the bottom reinforcement before the turbine can is lifted into place. A 3 ton teleporter is used to assist with the installation of the reinforcement. The teleporter lifts the reinforcement into the excavation and the steel fixer s individual lift of each bar to minimize back injuries and to install the reinforcement more efficiently. The turbine can requires a minimum 20 ton excavator to lift the can place. Once the can is installed the top section of reinforcement is installed. Once all the reinforcement has been installed and tied the 3 ton teleporter or 20 ton excavator is used to lift the formwork sections into place. Electrical conduits and earthing straps installed before the concrete pour
Figure: Bottom mat of reinforcement installed along with turbine can Figure: All the reinforcement installed and conduits for electrical cables
Figure: Formwork and earthing installed and secured before the foundation pour Stage 4: Foundation Pour The turbine foundation pour typically commences 3 to 4 days after the sub base pour depending on concrete supply and the availability of the 20 ton excavator to lift the turbine can into place. After the foundation reinforcement and formwork have be installed and secured the foundation pour is ready to commence. Approximately 120m3 C32/40 structural mix. Please see attached design mix. Crane hardstand to be fully constructed as concrete trucks will use the hardstand to turn Client to confirm proposed rate of concrete placement in m3/hr. etc 5 concrete trucks carrying 6m3 with one delivery per hour equals 30m3 per hour Client to confirm concrete supplier can supply the concrete in adequate time. Concrete to be fully placed in 5 hours Concrete pump and tester to be confirmed several days before the foundation pour Concrete pour to commence as early as possibly etc 8am Concrete tester to slump test each truck and take 4 sets of 3 cubes, 12 cubes in total. Each set of cubes should be tested at 7 days, 28 days and 56 days. After the concrete is poured 28 days is required for the concrete to achieve full strength
Concrete The structural concrete is a designed mix in accordance with BS 8500-1 The client is to adhere to the below requirements and where applicable provide C&F the correct documentation. Name of ready-mix supplier and location of batching plant(s); A copy of the ready-mix supplier s Certificate of accreditation; Full details of any admixtures proposed, for example manufacturers data sheets Nature and source of aggregates used at batch plants All mix information, as described above, shall be submitted to the C&F for review no later than 7 days in advance of the Contractors intention to supply a particular mix. Aggregates shall confirm to the British Standards listed in 4.3 of BS 8500-2 except that recycled concrete aggregate (RCA) and recycled aggregate (RA) shall not be used. In general multiple sources of aggregates within a mix shall not be permitted. Where proposed in a designed mix, admixtures shall comply with the requirements of BS EN 480 and BS EN 934. Contingency plans to deal with unforeseen delays in the delivery of ready mix concrete Concrete when deposited, shall have a temperature of not less than 5 C and not more than 30 C. The Clients attention is drawn to the Concrete Society publication Concrete Practice - Guidance on the practical aspects of concreting November 2008. In particular Chapters 13, 14 and 17. Sampling and testing of fresh concrete shall be carried out in accordance with BS EN 12350. Sampling and testing of hardened concrete shall comply with BS EN 12390. Compliance with the specified characteristic cube strength shall be based on tests made on cubes at an age of 28 days. Unless otherwise agreed with the Designer. Samples should be taken at the point of discharge from the delivery vehicle at approximately equal volume increments of concrete delivered. For each set of cubes 1No. shall be crushed at 7 days, 1No. at 28 days and 1No retained as a spare. Cubes shall be tested at an independent and BS EN ISO 9001 accredited testing laboratory. Compliance of cube strength with the specified design characteristic cube strength will be accepted if the mean of the 28 day test results ( target mean ) is equal to or greater than the specified Characteristic Cube Strength plus 4N/mm2 ( margin ). If the above criterion is not achieved for the 28 day test results of a particular cube set then the additional cube within that set shall be tested and the new result adopted, superseding the previous value for target mean. Typically this addition test is carried out at 56 days. Where cube tests are undertaken by the Contractor s mix supplier the results obtained may only be considered as complementary information. For the main concrete pour (Turbine foundation) a concrete pump with adequate reach is to be used to place the concrete. The method of placing concrete by excavator bucket is not to be used as cement separation from the aggregates may occur.
Back Filling Foundation Once the formwork has been stripped and removed the excavation around the foundation can be backfilled. The backfilling around the sides of the excavation is to be carried out in 200mm layers with the correct fill. Backfill material to be confirmed with C&F engineer. Backfilling layer should be of class type 1 (804) aggregate of 500mm thickness Care should be taken when placing the aggregate so not to damage PVC pipes or the electrical distribution cabinet.
Earthing The earthing is completed once the end of the steel reinforcement is complete. The reason earthing of the turbine is required is to prevent lightning strike. It is extremely important that the four earthing rods are secured in place to prevent obstruction. There are four earth cables connected to the turbine can The earth cables are connected to the can at the centre of the foundation Theses cables run along the top of the reinforcement frame to the end of the reinforcement frame Brackets are used at various locations the tie the cables to the reinforcement Denso tape is placed around the brackets to ensure that the bolts don t rust when imbedded into the concrete foundation Earthing rods are placed into the ground when foundation is been backfilled where the earth cable is attached If ground conditions are rocky the turbine may not get an earth, therefore client must over excavate or use special earthing powder
Crane Erection For the erection of the wind turbine the crane pad must be complete to the required specifications. Failing to do so will result in time delay which involves extra cost. Crane pad should be constructed as required in the site layout design Once the crane pad is constructed as required there should be no settlement There are two cranes required for the erection of the CF wind turbine which are approx. 100 ton each, therefore mobilization is significant. Cranes lift off two towers from the articulated truck which are put standing vertical Crane will then lift tower onto steel can were it will then be secured in place Same procedure will occur for second tower Crane then lifts turbine head onto steel frame, were the second crane will lift the blades onto the tower head. The blades are then secured in place 100 ton crane lifts tower head with blades attached into place where it is then secured onto tower mast Therefore it is important that the layout of the crane is perfect and adequate room for mobilization of the cranes Typical layout for the two cranes to ensure no delays occur onsite
Layout of cranes side by side. Enables articulated truck to drive behind the cranes
Picture above shows how the two cranes lift the tower mast from the articulated truck The picture above indicates how the big crane holds the turbine head while the small crane lifts the blades into place to be secured. This method prevents the blades hitting the ground