City of Frisco Engineering Standards

Engineering Standards
criteria for his/her structural design, that is the Design Engineer’s prerogative. In no case shall the
Design Engineer use geotechnical design criteria less conservative than the geotechnical
engineer's recommendations.
B. ROW Permit must be obtained prior to performing any boring within the City’s right-of-way.
C. The complexity of geological conditions and the type, length, and width of structure will
determine the number and locations of test holes required. The following should be considered by
the Design Engineer in coordination with the geotechnical engineer: Depth of test hole, location
of proposed grade relative to existing grade, channel relocations and/or channel widening, scour,
foundation loads, foundation types.
D. Locate the test holes in an accessible area. Avoiding overhead power lines and underground
utilities where possible, avoid steep slopes and standing or flowing water. Identify test hole
locations on the plans.
E. Provide a complete soil and bedrock classification and log record for each test hole, including all
pertinent information to complete the standard log. Location and surface elevation shall be shown
on the boring logs.
F. Perform the appropriate field and laboratory tests necessary to determine the soil shear strength
for proper soil evaluation and geotechnical design criteria. The geotechnical engineer shall
consider the short-term and long-term conditions. In addition, special attention is required when
testing highly plastic clays. Tests of these soil types shall be performed at a slow enough rate such
that any excess pore water pressure is dissipated, or in a manner that measures pore water
pressure.
G. Ground water elevations shall be included as part of the data acquisition. Site conditions may
require the installation of piezometers to establish a true groundwater surface elevation and
method of monitoring water surface fluctuations
H. Minimum boring requirements are as follows:
1. Slopes and Embankments including Bridge Approaches. Obtain soil borings for cuts
greater than 10’ or embankments taller than10’. The exploration shall include the following:
a. The soil under future embankments. Advance borings to a depth at least equal to the
embankment height or 20’, whichever is greater, unless a greater depth is recommended
by the geotechnical engineer.
b. Soil in proposed cuts. Advance borings to a depth of at least 15’ below the bottom of the
proposed cut, unless a greater depth is recommended by the geotechnical engineer.
2. Bridges
a. In general, drill test holes 10’ to 15’ deeper than the probable top elevation of the bridge
foundation.
b. Test holes near each abutment of the proposed structure plus a sufficient number of
intermediate holes to determine depth and location of all significant soil and rock strata.
Section 9 – Structural Design Requirements May 2012 Page 9-4