Do I really need wet-stamped constructions drawings?
Maybe! Maybe not! Check with your local building inspector or permitting authority. See also the FAQ regarding the need for a soils report.

Do I really need a soils report?
Maybe! Maybe not! This depends upon whether or not you need wet-stamped drawings. If you do, the professional engineer providing the wet-stamp will almost certainly require soils data. How else will she or he know what lies below grade?

SMarT_Foundations are designed to function satisfactorily in USCS (Unified Soil Classification System) Class 5 soils, which are the worst soils categorized in the International Building Code (IBC) and International Residential Code (IRC). However, the USCS classification does not cover all soil conditions on planet Earth – only those most likely encountered. For example, your site might have shallow bedrock, highly expansive soils, a low water table, reclaimed marshland or an ancient native-American burial site. What then?

So a more appropriate question is “Would I be wise to obtain a soils report?” And the answer is definitely yes. No one wants to spend more money than is necessary. But experience with our clients shows that in most cases, proper engineering typically costs no more than about 5% of the total installed cost of the turbine. If you are a contractor or professional installer, you probably want to avoid the potential liability of circumventing a reasonable standard of care. If you are a turbine owner, you’d probably like to sleep peacefully knowing you did the right thing. (See other FAQs on this topic.)

What’s the simplest and least expensive way to obtain soils data?
For complex or high-risk projects, most engineers will request a core boring followed by laboratory tests. This might be the case, for example, if you are building on a previously excavated and filled site or a site known to have multiple shallow layers of differing conditions. With this information, a geotechnical engineer will be able to issue a comprehensive soils report, usually including recommendations for foundation construction. But for small wind turbines, a simpler, less expensive approach usually suffices.

First, see if you can find an existing soils report for a location in close proximity to your site. For example, it is likely that a soils report was prepared when your home was originally constructed. Your engineer or building official may believe that report is sufficient for your turbine. If you can’t find an existing report, contact a few local geotechnical engineers to inquire about an “excavation observation.” The engineer, or an assistant, can arrange to be present while you excavate the foundation. By observing the soils, and possibly taking samples for laboratory tests, she or he can write a brief letter describing the site and recommending an allowable vertical soil bearing pressure, which is all that is typically required to ensure the adequacy of a SMarT_Foundation. In some cases, an engineer might be willing to evaluate excavation soil samples without actually being present during the excavation. This is a personal and professional decision at the engineer’s discretion.

Although excavation observation is relatively inexpensive, it has the added complication of requiring that the site be protected between the time of excavation and the time of pouring concrete. Safety is the primary concern, but there is also the matter of avoiding potential problems such as sloughing of the soil, water intrusion and freezing. We suggest you consult with your engineer and contractor to learn how to address these issues.

What tools will I need to install a SMarT_Foundation kit?
Common implements such as personal protective equipment, a tape measure, Phillips head screwdriver, hammer, ABS cement and PVC cement are used. Concrete pouring and finishing tools are needed.

What is the design wind speed for the SMarT_Foundation kits?
Every potential wind turbine site has a maximum design wind speed associated with it. It would be very inefficient to develop different foundation kits for every design wind speed that might be encountered. Therefore, only two design wind speeds have been selected for SMarT foundations – 110 mph (49.3 m/s) and 150 mph (67.3 m/s). 110 mph covers the vast majority of locations in the United States. For sites with a greater design wind speed, such as some locations in Florida and along the Gulf Coast, 150 mph is used as a design wind speed. The  drawings included with the SMarT_Foundation kits specify the details of foundation construction for these two cases. It is the responsibility of the installer to select the correct design wind speed and construct the foundation appropriately.

What is the design frost depth for the SMarT_Foundation kits?
Every potential wind turbine site has a frost depth associated with it. This information can be obtained from local building authorities. The bottom of the concrete foundation must be placed at or below the local frost depth. The parts provided in the foundation kit were selected for a 42-inch (1.07 m) frost depth, but instructions are provided to make simple adjustments for greater frost depths.

What do I do if I encounter unexpected soil conditions?
Our foundation kits are designed to be effective in typical soil conditions. But occasionally, unusual conditions are encountered. These include, for example, severely sloping terrain, expansive soils, low water-tables, marshland or sand. It may not be possible to use SMarT_Foundations in such cases, and the installer must then consult with a geotechnical and/or structural engineer to discuss alternatives. We suggest you contact TEP (Tower Engineering Professionals) at mgardner@tepgroup.net.

What if I want to use a tower with guy wires or a lattice tower?
You need to consult the manufacturer of your wind turbine. AnemErgonics has chosen to specialize only in the installation of free-standing monopole towers.

How much concrete will I need?
There are SMarT_Foundation kits for different wind turbines, tower heights, design wind speeds and frost depths. The amount of concrete required, which is different in each case, may be calculated from the drawings and specified dimensions for each particular case. As an example, a SMarT_Foundation for the Southwest Windpower Skystream 3.7 wind turbine, a 33.5 foot tower, 110 mph design wind speed and 42 inch frost depth requires approximately 3 cubic yards of concrete.

Are any special materials required?
Yes. SMarT_Foundation kits contain all the materials needed except concrete. But the concrete must contain a fiber reinforcement additive as specified in our drawings. Most ready-mix concrete batch plants offer this option at modest cost.

Are all the parts I need included in the SMarT_Foundation kit?
Yes and no. The kits include everything needed for the foundation, but are not intended to address the electrical interconnect. For convenience, a non-metallic rigid conduit (PVC) elbow and  some locating fittings are provided. However, everything needed for electrical grounding, lightning protection, buried conduit or wiring must be provided by the installer.

Can you help me with a special situation?
We’re certainly willing to listen. Please contact us.

What design standards are used for the SMarT_Foundation?
Several standards are invoked in the design of SMarT_Foundations. Probably the most important is the (International Electrotechnical Commission) IEC 61400-2 “Design Requirements for Small Wind Turbines.” This standard dictates the methods by which design loads are calculated and the safety factors to be used. We also incorporate many provisions of the International Building Code and the National Electrical Safety Code.

How much money will I save using the SMarT_Foundation kit?
We have participated in the installation of numerous foundations employing conventional techniques. Based on our analyses of the required parts, materials and labor required, we estimate the SMarT_Foundation kit may save in the range of 12 to 16 labor hours and up to $950. For larger foundations, such as for taller towers, any savings could be greater.

What wind turbines can be installed using SMarT_Foundations?
At the present time, kits are available for the Southwest Windpower Skystream 3.7 turbine on 33.5, 45 and 60 foot (10.2, 13.7 and 18.3 meter) towers. We plan to offer kits for other models and for other manufacturer’s turbines in the future, so we welcome your inquiries about use with other turbines.