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APPENDIX 2F
MODEL SPECIFICATIONS
Chapter 2
Helical Foundation Systems
12.5 Installation of helical anchors may be observed by representatives of the Owner for quality
assurance purposes. The Installing Contractor shall give the Owner at least 24 hours’ notice
prior to the anchor installation operations.
12.6 The helical anchor installation technique shall be such that it is consistent with the geotechnical,
logistical, environmental, and load carrying conditions of the project. The lead section shall be
positioned at the appropriate site survey stake location as determined from the plan drawings.
12.7 The helical anchor sections shall be advanced into the soil in a continuous manner at a rate of
rotation less than 25 revolutions per minute (rpm). Sufficient crowd shall be applied to advance
the helical anchor sections at a rate approximately equal to the pitch of the helix plate per
revolution. The rate of rotation and magnitude of down pressure shall be adjusted for different
soil conditions and depths. Extension sections shall be provided to obtain the required minimum
overall length and minimum torsional resistance as shown on the project Plans.
13
TERMINATION CRITERIA
13.1 The minimum final torsional resistance and/or any required anchor length and embedment depth
criteria, as specified in the Pre-Construction Submittals, must be satisfied prior to terminating
the anchor installation. In the event any helical anchor fails to meet these production quality
control termination criteria, the following remedies may be suitable if authorized by the Owner:
13.1.1 If the installation fails to meet the minimum torsional resistance criterion at the minimum
embedment length:
13.1.1.1 Continue the installation to greater depths until the torsional resistance criterion
is met, provided that, if a maximum length constraint is applicable, continued
installation does not exceed said maximum length constraint, or
13.1.1.2 Demonstrate acceptable anchor performance through anchor load testing, or
13.1.1.3 Replace the anchor with one having a different helix plate configuration. The
replacement anchor must not exceed any applicable maximum embedment
length criteria and either: (A) be embedded to a length that places the last
helix plate at least three times its own diameter beyond the depth of the first
helix plate of the replaced anchor and meet the minimum torsional resistance
criterion; or (B) pass anchor load testing criteria.
13.1.2 If the torsional resistance during installation reaches the helical anchor’s allowable
torque rating prior to satisfaction of the minimum embedment length criterion:
13.1.2.1 Terminate the installation at the depth obtained, or
13.1.2.2 Replace the anchor with one having a shaft with a higher torsional strength
rating. The replacement anchor must be installed to satisfy the minimum
embedment length criterion. It must also be embedded to a length that places
the last helix plate at least three times its own diameter beyond the depth of
the first helix plate of the replaced anchor without exceeding any applicable
maximum embedment length requirements and it must meet the minimum final
torsional resistance criterion, or