45 Foot Air Guyed Tower Kit

PRIMUS WIND POWER DOCUMENT #0070 REV C
PRIMUS WIND POWER Page 12 of 26
2/4/05
Buried Concrete: A buried concrete anchor may be the only solution if the ground is loose
gravel or sand or if it is too rocky for an auger or duckbill to be driven in. Buried concrete anchors
work well in any situation other than solid rock. A hole must be dug in the ground at the desired
anchor point. One good tactic is to purchase either augers or duckbills and if they cannot be used as
intended, then dig holes and cast them in concrete. Otherwise some other means of attachment
must be created for the guy wires, such as a loop of steel reinforcing bar (re-bar) or chain.
Holes for concrete anchors should be at least 2 feet in diameter and at least 3 feet deep. The
attachment should be placed in the hole and concrete or cement poured around it to a depth of at
least 1 foot. Once the concrete has set it should be buried before use.
Anchoring in rock: If your tower site has large rocks around it or is located on solid rock,
expansion bolts in the rock may be the best means of anchoring your guy wires and base tube. A
hole is drilled into the rock and the bolt is placed in the hole with an attachment hanger, a piece of
chain or other loop to connect to the guy wires.
For expansion bolts to work properly the rock must be of good quality and not fracture easily. If the
rock quality is poor a larger deeper hole must be drilled and a large eyebolt cemented into it. For very
hard rock such as granite and basalt, a ¼ inch diameter bolt 1 ½ inch deep can be used. For slightly
softer rock such as dacite, welded tufts and some denser varieties of sandstone, a 3/8-inch diameter bolt
3 to 4 inches deep should be used.
For softer types of rock, such as sandstone or limestone, a hole 1-inch diameter and 8 inches deep can
be drilled and an eyebolt 5/8 inch in diameter cemented into it. If cement is to be used, it should be
mixed just thin enough to pour and poured into the hole before the bolt is installed (a straw inserted to
the bottom of the hole before pouring will help prevent a bubble from forming). This will help to
insure that the cement goes to the bottom of the hole and help prevent bubbles that may compromise
the strength of the attachment. If expansion bolts are to be used, follow the instructions supplied with
the bolts. There are several different types of expansion bolts that are installed using different methods.