City of Frisco Engineering Standards

Engineering Standards
4. All water and wastewater crossings shall be encased with steel casing pipe in accordance with
Section 5.7C(1) Horizontal Boring, or approved equal. Casing pipe crossing railroad tracks
shall be designed to withstand E80 railroad loadings and shall extend to the right-of-way
lines.
5. Water valves, manholes, meters and other appurtenances shall be placed outside the limits of
the right-of-way.
6. Water main crossings shall include a valve on each side of the railroad crossing.
C. Creek Crossings
1. All water and wastewater mains crossing under a flowing stream or semi-permanent body of
water such as a marsh or pond shall be encased with concrete or steel casing pipe in
accordance with Section 5.7C(1) Horizontal Boring, or approved equal.
2. Wastewater main crossings shall include a manhole on each side of the creek crossing beyond
the top of creek bank.
3. Water main crossings shall include a valve beyond the top of creek bank on each side.
4. Water mains installed under and across creeks or ditches shall be designed according to the
following:
a. Water mains with less than 4’ of cover shall be protected by Class PC concrete
encasement a minimum of 10’ past the top of the embankment on each side.
b. Trench backfill under creeks and ditches shall consist of flowable backfill in accordance
with NCTCOG Item 504.2.3.4.
c. Rock bottom creeks and ditches shall include a 6” concrete cap at the surface in
accordance with NCTCOG Item 504.5.2.14 and Standard Drawing 3060.
d. Bank stabilization shall be required at all crossings and shall consist of a pervious
armored surface to resist scour and shear forces on all disturbed areas.
D. Elevated Crossings
1. Elevated crossings for water and wastewater mains should be avoided.
5.9 Corrosion Protection
A. Corrosion protection should be considered on all metal water and wastewater mains that are 16”
diameter or greater.
B. Corrosion investigation of metal pipeline sites shall include:
Section 5 – Water & Wastewater Design Requirements May 2012 Page 5-20