| (J) When trenching longitudinally, backfill or stabilized
sand shall be compacted to densities equal to that of the surrounding
soil. Compaction must meet all requirements listed in Item 400, relating
to excavation and backfill structures, of the department's publication,
Standard Specification for Construction and Maintenance of Highways,
Streets, and Bridges.
(K) Longitudinal installations shall be in uniform
alignment with the department's right of way and as near as practical
to the edge of the department's right of way line. Consideration shall
be given to allow safe clearance from adjacent installations.
(L) An additional 12 inches of depth are required
for installations within 50 feet of waterways, ditches, channels,
creeks, or culverts.
(M) As assigned corridors within the department's right
of way are finite at particular depths, the district may require the
placement of a utility facility below other facilities at necessary
clearances. The district may require encasements to allow the repair
or replacement of the utility facility without disturbing adjacent
utility facilities.
(5) Nonmetallic pipe detection. Where nonmetallic pipe
is installed, whether longitudinally or at a crossing, a durable metal
wire or other district-approved means of detection shall be concurrently
installed.
(6) Unsuitable conditions. The following conditions
are generally unsuitable or undesirable for pipeline crossings and
shall be avoided:
(A) deep cuts;
(B) locations near footings or bridges and retaining
walls;
(C) crossing intersections at-grade or ramp terminals;
(D) locations at cross-drains where the flow of water
may be obstructed;
(E) locations within basins or underpasses drained
by pump if the pipeline carries a liquid or liquefied gas; or
(F) terrain where minimum depth of cover would be difficult
to attain.
(7) Clearances. Except as specified in this subchapter,
there shall be a minimum of 12 inches vertical and horizontal clearance
between a new utility facility and an existing utility facility, unless
a greater clearance is required by the district. However, if an installation
of another utility facility or highway feature cannot take place without
disturbing an existing utility facility, the district may require
a minimum clearance of 24 inches.
(8) Drainage easements. Where it is necessary for pipelines
to cross department drainage easements outside of the right of way,
the depth of cover shall be as specified for each type of utility
facility. In cases where soil conditions are such that erosion might
occur, or where it is not feasible to obtain specified depth, it shall
be the responsibility of the utility to install retards, energy dissipators,
encasement, or concrete or equivalent slabs/caps over the pipe, as
approved by the department. Where grades on the pipelines must be
maintained, such as gravity flow sewer lines, each case will be reviewed
on an individual basis. The main purpose of the department's drainage
easement is to carry drainage water and the drainage may not be obstructed.
The utility is responsible for obtaining any other approvals or rights
required to occupy the drainage easement.
(9) Existing installations in a highway or transportation
project. At the district's discretion, existing longitudinal utility
facilities in a highway or transportation project that otherwise meet
the requirements of this subchapter may remain in place if the utility
facilities:
(A) can be maintained in accordance with §21.37(b)(2)
of this subchapter (relating to Design); and
(B) are not located under the pavement structure or
shoulder of any proposed or existing highway.
(10) Markers. If a high pressure pipeline crosses a
highway, the utility shall place a readily identifiable, durable,
and weatherproof marker over the centerline of the pipe at each right
of way line. Readily identifiable, durable, and weatherproof markers
shall be placed at a minimum distance of 500 feet apart or line of
sight at the right of way line for pipelines installed longitudinally
within the right of way. All markers shall indicate the name, address,
emergency telephone number of the utility, and offset from the right
of way line for longitudinal placement. For gas, petroleum, or saltwater
pipelines, the pipeline product, operating pressure, and depth of
pipe below grade shall also be indicated on the markers. At locations
where underground utility facilities have been allowed to cross at
an angle other than 90 degrees to centerline, the district may require
additional markers in the medians and outer separations of the highway.
(b) Gas and liquid petroleum pipelines and saltwater
pipelines.
(1) Low-pressure pipelines.
(A) Depth of cover for crossings. Depth of cover is
the depth to the top of the encasement, or the carrier pipe if encasement
is not used. Where materials and other conditions justify, such as
on existing pipelines remaining in place, the district may require
a minimum depth of cover under the pavement structure of 12 inches
or one-half the diameter of the pipe, whichever is greater.
(i) For encased low-pressure gas pipelines, the minimum
depth of cover is:
(I) 60 inches or one-half the diameter of the pipe,
whichever is greater, below the lowest point of the crossed grade;
or
(II) 48 inches if the pipeline is outside of the pavement
structure or 60 inches under ditches (original unsilted flowline).
(ii) For unencased low-pressure gas pipelines, the
minimum depth of cover is:
(I) 60 inches under the lowest point of the crossed
grade;
(II) 48 inches if the pipeline is outside of paved
areas; or
(III) a lesser depth than applicable under subclause
(I) or (II) of this clause if the lesser depth is authorized by the
district where a reinforced concrete slab is used to protect the pipeline.
(B) Depth of cover for longitudinal placement. The
minimum depth of cover for longitudinal installations is 48 inches.
(C) Encasement. Low-pressure gas pipelines crossing
the pavement shall be placed in a high-density polyethylene (HDPE)
or equivalent encasement. The district may waive this encasement requirement
if:
(i) the pipeline is:
(I) of welded steel construction; and
(II) is protected from corrosion by cathodic protective
measures or cold tar epoxy wrapping; and
(ii) the utility signs a written agreement that the
pavement will not be cut for pipeline repairs at any time in the future.
(D) Vents. One or more vents shall be provided for
each encasement or series of encasements. For encasements longer than
150 feet, vents shall be provided at both ends. On shorter encasements,
a vent shall be located at the high end with a marker placed at the
low end. Vents shall be placed at the right of way line immediately
above the pipeline, situated so as not to interfere with highway maintenance
or be concealed by vegetation, and may not be greater than six inches
in diameter. The utility's name, address, and emergency telephone
number shall be shown on each vent.
(E) Aboveground appurtenances. Except for vents, pipeline
markers, and gas rectifiers, aboveground utility appurtenances for
gas lines are prohibited within department's right of way.
(2) High-pressure pipelines and saltwater pipelines.
(A) Depth of cover for crossings.
(i) Depth of cover is the depth to the top of the encasement
or carrier pipe if an encasement is not used. Where materials and
other conditions justify, such as on existing lines remaining in place,
the district may approve a minimum depth of cover under the pavement
structure of 48 inches or one-half the diameter of the pipe, whichever
is greater. For encased high-pressure pipeline, the minimum depth
of cover is:
(I) 60 inches or one-half the diameter of the pipe,
whichever is greater, below the lowest point of the crossed grade
unless a greater depth is required by the district; or
(II) 48 inches if the pipeline is outside of the pavement
structure, or 60 inches if under a ditch, below the lowest point of
grade.
(ii) Where a reinforced concrete slab is used to protect
the pipeline, the district may authorize a reduction in the depths
specified in this subparagraph.
(iii) For unencased high-pressure pipelines, the minimum
depth of cover is as follows:
(I) 60 inches under the lowest point of the crossed
grade, subject to subparagraph (D) of this paragraph; or
(II) 60 inches under the lowest point of grade if the
pipeline is placed outside the pavement structure or under a ditch.
(B) Depth of cover for longitudinal placement. The
minimum depth of cover is 48 inches.
(C) Encasement. The encasement must be a vented steel
pipe.
Cont'd... |
