City of Frisco Engineering Standards

Engineering Standards
Section 5 – Water & Wastewater Design Requirements
5.1 Water System - General
A. The intent of the water system design requirements is to list minimum requirements for public
water distribution and transmission system facilities and appurtenances. Private fire service
mains shall also be designed according to these water system design requirements and the City’s
Fire Code and the National Fire Protection Association (NFPA) 24, Standard for the Installation
of Private Fire Service Mains and Appurtenances, latest revision.
B. Design criteria for all water systems shall comply with Texas Commission on Environmental
Quality (TCEQ) Chapter 290, Subchapter D (Rules and Regulations for Public Water Systems),
latest revision. Chapter 290 is included in Part I of Title 30 of the Texas Administrative Code.
C. Line sizes shall comply with the Water Distribution System Capital Improvement Plan.
D. Water mains shall be sized and extended through the limits of a development to serve adjacent
properties.
E. Dead end water mains are not allowed unless approved in writing by the Director of Engineering
Services; however, if approved, an automatic flushing device shall be provided (See 5.1.12).
Automatic flushing devices shall drain via a pipe system to the storm sewer system.
5.1.1 Water Main Location
A. Water mains 12” and smaller shall be installed 2’ from the back of the curb, as measured to the
centerline of pipe.
B. Water mains larger than 12” shall be installed at least 3’ from the back of curb as measured to the
centerline of pipe.
C. Water mains shall be designed to minimize bends and fittings and follow right-of-way or
centerline alignment curves at a uniform distance from the right-of-way or centerline.
D. Dead end water mains shall extend a minimum of 5’ beyond the edge of the pavement. If adjacent
to a fitting, extend a minimum of 20’ or one pipe joint beyond fitting.
5.1.2 Horizontal and Vertical Alignment
A. A clearance of 18” shall be maintained when crossing storm drain systems. Where minimum
clearance cannot be achieved, water mains shall be encased in 6” of concrete in accordance with
the standard detail.
B. Lines 16” and smaller shall have a minimum cover of 4’.
C. Lines larger than 16” shall have a minimum cover of 6’.
D. Waters mains shall be designed as straight as possible following the existing or proposed grade at
the minimum depth of cover. Bends shall be provided where vertical slope changes exceed 80%
of the manufacturer’s recommended joint deflection.
E. Excessive high points that trap air and restrict water flow shall be avoided.
Section 5 – Water & Wastewater Design Requirements May 2012 Page 5-2