Project Drills For Making Wind Mill or Telecom Tower
1 Site must be accessible –must be able to deliver and erect turbines over 400’ tallNeed adequate level ground around each turbine site –crane pads, laydown areas Need adequate spacing between rows of turbines –1/3 to ½ mile
Access Roads –Gravel roads linking wind turbine strings to existing roads.
Electrical Collection System –Cables that electrically connect wind turbines to the project substation.
Project Substation –Steps up project generation to interconnection voltage. Operations & Maintenance Building –Houses central office, computer systems for facility operations, equipment storage and maintenance areas.
2 Construction Sequence
A Prepare road for construction Install culverts, fords at drainage areas
Tower Pier Foundation with Spread Footer
Excavation depth to ~8ft and+50ft base elevation.Mud Mat –2 to 4 inches lean concrete.Rebar cage and anchor bolts cage.Concrete (5000 psi) formed and poured in two lifts. Backfill with native soil
Using 5/8” plywood and 7’ lengths of 2” X 4”, build 2 forms for bracing the foundation. The forms will be used to contain the concrete in the pit.
Dig a 7’ X 7’ X 30” hole
Construct a frame around the outer edge of the hole using the 10’ pieces of 2 X 4. On two opposite sides, place the forms in the hole. The distance between the forms should be 7’. The concrete will pour right up to the top of this frame, level appropriately. The forms will be removed after your concrete sets. Be sure to mark center wall lines so that you know where the wall forms will be placed.
Steel rebar reinforcement is critical to making sure your foundation can bear wall stress adequately. Build two rebar grids from the 6’ 15M rebar pieces and place in the hole. Space a 7 X 7 grid as equally as possible. Use rebar ties to secure every intersection of rebar.
Hammer 4 stakes into the ground on the on the outside of the hole. Stakes should be placed as shown. Use the stakes to level two 10’ 2 X 4s across the hole. The 2 X 4s should be no more than ¼” above the frame surrounding the hole. The gap will help in finishing the concrete. Place the plywood anchor pattern and 2 X 8 as shown. The holes must be spaced correctly in order to place the tower on the foundation.
Hang the rebar either using rebar ties or anchors. The bottom rebar grid should be placed 3” above the bottom of the hole, while the second rebar grid should be placed 3” from the top of the hole
Install anchor bolts in your foundation, which will be used to secure walls to the foundation later. The number and location of anchor bolts needed is also set by local building codes Place the tower anchors through each of the 3 – 1 3/8” cut outs on the plywood template, so that the threaded end of the anchors protrudes not more than 6” (0.15m) from the top of the concrete. Engage and tighten the 1 1/4” jam nuts onto the tower anchors, 1 jam nut is placed below the plywood and one on top. The other end of the anchors are tied to the rebar using rebar wire to ensure they do not move during the concrete pour, also ensure that the toes of the anchors are POINTED OUTWARDS
Place the grounding plate on the ground in the bottom of the foundation pit. Attach the grounding clamp to the plate and to one of the tower legs with the short cooper wire strip. Note that the Electrical Inspector may request to inspect the grounding method BEFORE concrete is poured
Carefully pour the concrete into the foundation pit. Ensure that the three tower legs have remained vertical and that the conduit has remained in the proper position.
Install a vapor barrier over the gravel or sand before you pour the concrete slab. This will help prevent any moisture from rising into your slab. In some locations where moisture is prevalent, a vapor barrier below the sand or gravel may also be needed.
Place wire mesh in the center of your slab and rebar in the footing areas to increase rigidity and prevent any cracks in the concreteWait for the concrete to dry. Then remove the three jam nuts from the tower legs and remove the plywood template. Remove all of the forms and wood frames used in construction.
TOWER ERECTION
The 80-meter turbine tower is composed of four cylindrical steel sections.The four tower sections are typically unloaded adjacent to each wind turbine foundation to minimize handling of these heavy steel components.Each tower section weighs between 35 and 50 tons.The lower tower section is set first. A flange on the bottom of this 15’ diameter section allows it to be bolted to the top of the foundation pedestal.
After the tower sections are set, the nacelle is raised and bolted to the top of the tower.A 2 megawatt class turbine nacelle weighs over 100 tons.
The rotor assembly is erected last. The rotor consists of three blades and a hub that mount on the front of the nacelle. Typically, the blades and hub are assembled on the ground and then raised as a single unit, called the rotor, and attached to the nacelle.
Access Roads –Gravel roads linking wind turbine strings to existing roads.
Electrical Collection System –Cables that electrically connect wind turbines to the project substation.
Project Substation –Steps up project generation to interconnection voltage. Operations & Maintenance Building –Houses central office, computer systems for facility operations, equipment storage and maintenance areas.
2 Construction Sequence
A Prepare road for construction Install culverts, fords at drainage areas
Install Base Material: Place geo-fabric or Geo-Grid
Place 6 to 8 inches of gr Finish road profile slightly above natural grade with a 2% crown in the center to promote drainage. Construct shoulders with a maximum of 2% side slope for crane travel
Tower Pier Foundation with Spread Footer
Footing: 50-80 ft diameter, 4ft depth with taper.
Pier: 16-20 ft diameter, 3ft height.
Apron: Compacted area over footing diameter with 6 in rock surface.
Excavation depth to ~8ft and+50ft base elevation.Mud Mat –2 to 4 inches lean concrete.Rebar cage and anchor bolts cage.Concrete (5000 psi) formed and poured in two lifts. Backfill with native soil
Using 5/8” plywood and 7’ lengths of 2” X 4”, build 2 forms for bracing the foundation. The forms will be used to contain the concrete in the pit.
Dig a 7’ X 7’ X 30” hole
Construct a frame around the outer edge of the hole using the 10’ pieces of 2 X 4. On two opposite sides, place the forms in the hole. The distance between the forms should be 7’. The concrete will pour right up to the top of this frame, level appropriately. The forms will be removed after your concrete sets. Be sure to mark center wall lines so that you know where the wall forms will be placed.
Steel rebar reinforcement is critical to making sure your foundation can bear wall stress adequately. Build two rebar grids from the 6’ 15M rebar pieces and place in the hole. Space a 7 X 7 grid as equally as possible. Use rebar ties to secure every intersection of rebar.
Hammer 4 stakes into the ground on the on the outside of the hole. Stakes should be placed as shown. Use the stakes to level two 10’ 2 X 4s across the hole. The 2 X 4s should be no more than ¼” above the frame surrounding the hole. The gap will help in finishing the concrete. Place the plywood anchor pattern and 2 X 8 as shown. The holes must be spaced correctly in order to place the tower on the foundation.
Hang the rebar either using rebar ties or anchors. The bottom rebar grid should be placed 3” above the bottom of the hole, while the second rebar grid should be placed 3” from the top of the hole
Install anchor bolts in your foundation, which will be used to secure walls to the foundation later. The number and location of anchor bolts needed is also set by local building codes Place the tower anchors through each of the 3 – 1 3/8” cut outs on the plywood template, so that the threaded end of the anchors protrudes not more than 6” (0.15m) from the top of the concrete. Engage and tighten the 1 1/4” jam nuts onto the tower anchors, 1 jam nut is placed below the plywood and one on top. The other end of the anchors are tied to the rebar using rebar wire to ensure they do not move during the concrete pour, also ensure that the toes of the anchors are POINTED OUTWARDS
Place the grounding plate on the ground in the bottom of the foundation pit. Attach the grounding clamp to the plate and to one of the tower legs with the short cooper wire strip. Note that the Electrical Inspector may request to inspect the grounding method BEFORE concrete is poured
Carefully pour the concrete into the foundation pit. Ensure that the three tower legs have remained vertical and that the conduit has remained in the proper position.
Install a vapor barrier over the gravel or sand before you pour the concrete slab. This will help prevent any moisture from rising into your slab. In some locations where moisture is prevalent, a vapor barrier below the sand or gravel may also be needed.
Place wire mesh in the center of your slab and rebar in the footing areas to increase rigidity and prevent any cracks in the concreteWait for the concrete to dry. Then remove the three jam nuts from the tower legs and remove the plywood template. Remove all of the forms and wood frames used in construction.
TOWER ERECTION
The 80-meter turbine tower is composed of four cylindrical steel sections.The four tower sections are typically unloaded adjacent to each wind turbine foundation to minimize handling of these heavy steel components.Each tower section weighs between 35 and 50 tons.The lower tower section is set first. A flange on the bottom of this 15’ diameter section allows it to be bolted to the top of the foundation pedestal.
After the tower sections are set, the nacelle is raised and bolted to the top of the tower.A 2 megawatt class turbine nacelle weighs over 100 tons.
The rotor assembly is erected last. The rotor consists of three blades and a hub that mount on the front of the nacelle. Typically, the blades and hub are assembled on the ground and then raised as a single unit, called the rotor, and attached to the nacelle.
