Section 5. Structures and Utilities

Snow is crystallized frozen water and water is heavy. Water weighs about 62 pounds per cubic foot, so one inch of water weighs a little more than five pounds per square foot.

That same inch of water is equivalent to about 10 inches of dry, cold snow. This means each inch of dry, cold snow weighs about a half a pound per square foot. And the type of snow makes a difference:

• 12 inches of dry snow equals 5-6 pounds per square foot of load.
• 3 inches of wet snow also equals about 5 pounds per square foot of load.

Imagine the pressure this creates sitting on a roof. Agricultural buildings should be built to carry from 24 to 34 pounds of snow per square foot depending on location.

Check your insurance policy to determine if snow load is covered. Sometimes structural failure due to snow is not covered on agricultural buildings without a purchased rider.

• The angle at which the wind strikes the structure
• The shape of the structure (height, width, etc.)

Preventing wind damage involves strengthening areas where buildings could come apart. The walls, roof and foundation must be strong, and the attachments between them must be strong and secure. For a structure to resist hurricane and weak tornadic winds, it must have a continuous load path from the roof to the foundation -- connections that tie all structural parts together and can resist types of wind loads that could push and pull on the building in a storm. Depending on the location, a typical “wind load” is 80 mph or 16 lb/ft2.

Wind exerts three types of forces on a structure:

• Uplift load - Wind flow pressures that create a strong lifting effect, much like the effect on airplane wings. Wind flow under a roof pushes upward; wind flow over a roof pulls upward.
• Shear load – Horizontal wind pressure that could cause racking of walls, making a building tilt.
• Lateral load – Horizontal pushing and pulling pressure on walls that could make a structure slide off the foundation or overturn.

High wind pressures can collapse doors and windows, rip off roofing and roof decking and destroy gable end walls. Roof overhangs and other features that tend to trap air beneath them, resulting in high uplift forces, are particularly susceptible to damage. Broken windows and doors can expose the building contents to serious damage from internal wind pressures and water entry.

The actual effects of wind forces on farm buildings depend on their design, construction and surroundings. Local windbreaks – trees – can help to reduce these effects.

Check the wind zone of your location: http://www.fema.gov/pdf/library/ism2_s1.pdf and be sure your buildings can resist the wind speeds in your region. Your insurance company or county building and inspection department may be able to help determine what the wind load is for each of your structures. Wind load capacity is important to keep in mind when designing and building new structures, especially if you live in a region of the U.S. where high winds occur frequently.

Thoroughly investigate the location, quantity and quality of water that is available. Generally, a well yield or stream flow of 6 to 15 gallons per minute will be required for each irrigated acre, depending on the crop and the soil at your location. If you use irrigation for frost protection, you will need a flow rate of 45 to 65 gallons per minute per acre. When using a farm pond as your water source, 1 to 1.5 acre feet of water should be stored for each acre to be irrigated.

Consult your state department of natural resources for information about surface and ground water supplies available for public and private use. The department may be able to provide you with an estimate of the size, geologic makeup and yield of aquifers in your area. Also consider consulting a hydrogeologist or local well driller. They are often listed in the telephone directory or Yellow Pages. The natural resources department may be able to provide a list of hydrologists and well drillers who provide services in your area.

Water quality testing is essential, especially for livestock operations and intensive systems such as greenhouses. Testing is available from private laboratories. Local health departments may also provide some services. In some cases, water treatment may be needed.

When you evaluate your water supply, be sure that it is adequate, of suitable quality, and plentiful enough to meet your needs. The supply should also be economically accessible and legally available. In some cases, a permit may be required to use a water source or withdraw over a specified amount.

Be sure you have an adequate water supply to fight fires. These water sources should be identified and marked with signs. The location of water sources, such as wells and ponds, and fire fighting equipment such as hoses, should be shared with family members, employees and emergency personnel.

Keep all electrical wiring up to code, and be sure all electrical
devices in barns and sheds are UL approved. Hire only certified electricians to work on your structures. Poor wiring increases the risk of fire, one of the most common emergencies on an operation.

Be sure to keep electrical boxes secured from unauthorized access.

When selecting a generator, don’t focus only on the price per kilowatt of generator capacity. Determine the size needed to power only essential electric loads. Add up these loads to determine the kilowatt capacity needed. Also keep in mind that electric motors draw three to five times more power at starting than when running under full load. The type of generator (manual, semiautomatic or automatic) will also influence the correct load rating and the cost. A manual unit allows selection of the equipment to be connected during the emergency, but requires personnel to start and connect the generator and to change equipment connections to the electrical system to stay within generator capacity.

Notify your local electric utility company if you plan to use a standby generator in case of power failure.

• Engine-driven generators – The generator and the engine powering the generator are often sold together as a single package or “genset.” It can be an automatic-start standby generator or a manual start (pull cord or manual key) design. Generators are sized according to a kilowatt (KW) power rating. Engine-driven generators range from large permanently mounted diesel units that are used for standby systems to small portable gasoline engine generators just large enough to power vital appliances.
• Tractor-driven generators – These generators are powered from an agricultural tractor’s power take-off (PTO) shaft. These models have a lower initial cost and are expected to require less maintenance because an engine is eliminated. Tractor-powered generators are often mounted on a trailer or on a three-point hitch mounted carrier so they can be towed to different locations to power welders or other equipment in areas remote from electrical power, or serve as a "service drop".

Whether it's a direct-connected engine-driven unit or one driven by a tractor power take-off (PTO), be sure a double-pole, double-throw transfer switch is properly installed by a licensed electrician if the generator is to be connected directly to the farm wiring. This switch disconnects the commercial electricity supplier power source (the electric power company lines) from the farm electrical wiring and prevents electricity made by the generator from flowing onto utility lines where it could electrocute members of the repair crew. The switch must have the capacity to carry the total load of the farm or building it feeds, even though the generator has less capacity. When the switch is in its second position, the generator is separately connected to only the farm’s (or building) electrical wiring. Extension cords typically connect individual equipment (freezers, portable lights) to small generators.