| (i) Where a new potable waterline parallels an existing,
non-pressure or pressure rated wastewater main or lateral and the
licensed professional engineer licensed in the State of Texas is able
to determine that the existing wastewater main or lateral is not leaking,
the new potable waterline shall be located at least two feet above
the existing wastewater main or lateral, measured vertically, and
at least four feet away, measured horizontally, from the existing
wastewater main or lateral. Every effort shall be exerted not to disturb
the bedding and backfill of the existing wastewater main or lateral.
(ii) Where a new potable waterline parallels an existing
pressure-rated wastewater main or lateral and it cannot be determined
by the licensed professional engineer if the existing line is leaking,
the existing wastewater main or lateral shall be replaced with at
least 150 psi pressure-rated pipe. The new potable waterline shall
be located at least two feet above the new wastewater line, measured
vertically, and at least four feet away, measured horizontally, from
the replaced wastewater main or lateral.
(iii) Where a new potable waterline parallels a new
wastewater main, the wastewater main or lateral shall be constructed
of at least 150 psi pressure-rated pipe. The new potable waterline
shall be located at least two feet above the wastewater main or lateral,
measured vertically, and at least four feet away, measured horizontally,
from the wastewater main or lateral.
(B) New waterline installation - crossing lines.
(i) Where a new potable waterline crosses above a wastewater
main or lateral, the segment of the waterline pipe shall be centered
over and must be perpendicular to the wastewater main or lateral such
that the joints of the waterline pipe are equidistant and at least
nine feet horizontally from the centerline of the wastewater main
or lateral. When crossing an existing wastewater main or lateral and
it is disturbed or shows signs of leaking, the wastewater main or
lateral shall be replaced for at least nine feet in both directions
(18 feet total) with at least 150 psi pressure-rated pipe embedded
in cement stabilized sand (see clause (v) of this subparagraph) for
the total length of one pipe segment plus 12 inches beyond the joint
on each end.
(I) The potable waterline shall be at least two feet
above an existing, non-pressure rated wastewater main or lateral.
(II) The potable waterline shall be at least six inches
above an existing, pressure-rated wastewater main or lateral.
(ii) Where a new potable waterline crosses a new, non-pressure
rated wastewater main or lateral, the segment of the waterline pipe
shall be centered over and shall be perpendicular to the wastewater
main or lateral such that the joints of the waterline pipe are equidistant
and at least nine feet horizontally from the centerline of the wastewater
main or lateral. The potable waterline shall be at least two feet
above the wastewater main or lateral. Whenever possible, the crossing
shall be centered between the joints of the wastewater main or lateral.
The wastewater pipe shall have a minimum pipe stiffness of 115 psi
at 5.0% deflection. The wastewater main or lateral shall be embedded
in cement stabilized sand (see clause (v) of this subparagraph) for
the total length of one pipe segment plus 12 inches beyond the joint
on each end. The materials and method of installation shall conform
to one of the following options:
(I) Within nine feet horizontally of either side of
the waterline, the wastewater pipe and joints shall be constructed
with pipe material having a minimum pressure rating of at least 150
psi. An absolute minimum vertical separation distance of two feet
shall be provided. The wastewater main or lateral shall be located
below the waterline.
(II) All sections of wastewater main or lateral within
nine feet horizontally of the waterline shall be encased in an 18-foot
(or longer) section of pipe. Flexible encasing pipe shall have a minimum
pipe stiffness of 115 psi at 5.0% deflection. The encasing pipe shall
be centered on the waterline and shall be at least two nominal pipe
diameters larger than the wastewater main or lateral. The space around
the carrier pipe shall be supported at five-foot (or less) intervals
with spacers or be filled to the springline with washed sand. Each
end of the casing shall be sealed with watertight non-shrink cement
grout or a manufactured watertight seal. An absolute minimum separation
distance of six inches between the encasement pipe and the waterline
shall be provided. The wastewater line shall be located below the
waterline.
(iii) When a new waterline crosses under a wastewater
main or lateral, the waterline shall be encased as described for wastewater
mains or laterals in clause (ii) of this subparagraph or constructed
of ductile iron or steel pipe with mechanical or welded joints as
appropriate. An absolute minimum separation distance of one foot between
the waterline and the wastewater main or lateral shall be provided.
When a new waterline crosses under a wastewater main, the procedures
in §217.53(d) of this title (relating to Pipe Design) must be
followed.
(iv) Where a new potable waterline crosses a new, pressure
rated wastewater main or lateral, one segment of the waterline pipe
shall be centered over and shall be perpendicular to the wastewater
line such that the joints of the waterline pipe are equidistant and
at least nine feet horizontally from the center line of the wastewater
main or lateral. The potable waterline shall be at least six inches
above the wastewater main or lateral. Whenever possible, the crossing
shall be centered between the joints of the wastewater main or lateral.
The wastewater pipe shall have a minimum pressure rating of at least
150 psi. The wastewater main or lateral shall be embedded in cement
stabilized sand (see clause (v) of this subparagraph) for the total
length of one pipe segment plus 12 inches beyond the joint on each
end.
(v) Where cement stabilized sand bedding is required,
the cement stabilized sand shall have a minimum of 10% cement per
cubic yard of cement stabilized sand mixture, based on loose dry weight
volume (at least 2.5 bags of cement per cubic yard of mixture). The
cement stabilized sand bedding shall be a minimum of six inches above
and four inches below the wastewater main or lateral. The use of brown
coloring in cement stabilized sand for wastewater main or lateral
bedding is recommended for the identification of pressure rated wastewater
mains during future construction.
(5) Waterline and wastewater main manhole or lateral
manhole or cleanout separation. The separation distance from a potable
waterline to a wastewater main manhole or lateral manhole or cleanout
shall be a minimum of nine feet. Where the nine-foot separation distance
cannot be achieved, the potable waterline shall be encased in a joint
of at least 150 psi pressure class pipe at least 18 feet long and
two nominal sizes larger than the new conveyance. The space around
the carrier pipe shall be supported at five-foot intervals with spacers
or be filled to the springline with washed sand. The encasement pipe
shall be centered on the crossing and both ends sealed with cement
grout or manufactured sealant.
(6) Location of fire hydrants. Fire hydrants shall
not be installed within nine feet vertically or horizontally of any
wastewater main, wastewater lateral, or wastewater service line regardless
of construction.
(7) Location of potable or raw water supply or suction
lines. Suction mains to pumping equipment shall not cross wastewater
mains, wastewater laterals, or wastewater service lines. Raw water
supply lines shall not be installed within five feet of any tile or
concrete wastewater main, wastewater lateral, or wastewater service
line.
(8) Proximity of septic tank drainfields. Waterlines
shall not be installed closer than ten feet to septic tank drainfields.
(f) Sanitary precautions and disinfection. Sanitary
precautions, flushing, disinfection procedures, and microbiological
sampling as prescribed in AWWA standards for disinfecting water mains
shall be followed in laying waterlines.
(1) Pipe shall not be laid in water or placed where
it can be flooded with water or sewage during its storage or installation.
(2) Special precautions must be taken when waterlines
are laid under any flowing or intermittent stream or semipermanent
body of water such as marsh, bay, or estuary. In these cases, the
water main shall be installed in a separate watertight pipe encasement
and valves must be provided on each side of the crossing with facilities
to allow the underwater portion of the system to be isolated and tested
to determine that there are no leaks in the underwater line. Alternately,
and with the permission of the executive director, the watertight
pipe encasement may be omitted.
Cont'd... |
