City of Frisco Engineering Standards

Engineering Standards
F. The Inlet Spreadsheet provided in Figure 2 shall be provided with the construction plans for
review by the City. A description of each of the columns shown in the inlet spreadsheet is
provided below:
• Column 1: Design Point for Inlet
• Column 2: Inlet number
• Column 3: Location of inlet by storm drain station number
• Column 4: Drainage area designation for incremental area
• Column 5: Drainage area size (acres)
• Column 6: Runoff coefficient (C)
• Column 7: Time of concentration (minutes)
• Column 8: 100-year intensity (in/hr)
• Column 9: 100-year runoff, Q=CIA (cfs)
• Column 10: 100-year carryover flow from upstream inlet (cfs)
• Column 11: 100-year total gutter flow (Column 9 + Column 10) (cfs)
• Column 12: Percentage of flow traveling from lower station side of sag inlet based on
percentage of drainage area and carryover flow from that side (cfs)
• Column 13: Percentage of flow traveling from higher station side of sag inlet based on
percentage of drainage area and carryover flow from that side (cfs)
• Column 14: 100-year total gutter flow reaching the lower station side of the sag inlet
(Column 11 times Column 12) (cfs)
• Column 15: 100-year total gutter flow reaching the higher station side of the sag inlet
(Column 11 times Column 13) (cfs)
• Column 16: Longitudinal slope of the approach gutter. For sag inlets, half the longitudinal
slope of the approach gutter on the lower station side of the inlet (S 0 ) (ft/ft)
• Column 17: Not used for on-grade inlets. For sag inlets, half the longitudinal slope of the
approach gutter on the higher station side of the inlet (S 0 ) (ft/ft)
• Column 18: Street crown section type (straight crown [“rooftop”] or parabolic)
• Column 19: Roadway cross slope “Sx” (%)
• Column 20: Manning’s roughness coefficient (n) for pavement (0.0175 for concrete
pavement)
Section 4 – Drainage Design Requirements May 2012 Page 4-16