City of Frisco Engineering Standards

Engineering Standards
2. PVR-TxDOT Tex-124-E Alternative: The PVR shall be calculated based upon 20’ moisture
penetration and shall provide moisture treatment depth to limit the PVR to 4.5”. Submit all
calculations and assumptions involved in calculating the PVR and the recommended depth of
moisture treatment to the City for review upon request.
3. Moisture treatment to a minimum of 3 percentage points above optimum moisture content at
a minimum of 95 percent standard Proctor (ASTM D 698) shall be required for at least 2’ of
the subgrade. Thicker zones of moisture treatment may be required depending upon the
average swell potential. The thickness shall be determined in accordance with Figure 3.1 or
as determined by calculations.
Type A & B
Type C D E F G Alleys
FIGURE 3.1: Recommended Depth of Moisture
K. The upper portion of the subgrade shall be lime stabilized in accordance with the laboratory
determined lime percentage. A minimum subgrade thickness of 8” for residential streets and 12”
for arterial streets shall be lime stabilized.
L. Moisture treatment and lime stabilization shall extend at least 4’ beyond the edge of pavement. A
moisture barrier consisting of at least 10 mil poly sheeting shall be placed horizontally on the
subgrade beyond the pavement edge and extend at least 6’ on either side of the pavement neat
line after final compaction. The barrier shall be covered with at least 8” of lightly compacted soil.
3.04 Pavement Design Requirements
A. The roadway pavement thickness shall be based on subgrade investigation and Pavement Design
Catalog.
Section 3 – Pavement and Subgrade Design Requirements May 2012 Page 3-5