A.
This standard is intended as a guide to minimum good
practices in the installation of asbestos-cement water pipe and cast-iron
fittings and is based on Standard C 603-65 of the American Water Works Association.
For specific projects, a thorough review of the application of the standard
is anticipated in conjunction with the engineering review process of the Planning
Board of the Town of Somers, and specific construction details may then be
required of developers to provide a well-designed and -constructed water system.
It is anticipated that minor further modifications may also be directed to
respond to field conditions when construction is under way.
B.
The pipe selected shall be manufactured in accordance
with the provisions of American Water Works Association Standard C 400, Standard
for Asbestos-Cement Fittings and Water Pipe.
A.
CONTRACTOR
DEVELOPER
ENGINEER
INSPECTOR
As used in this chapter, the following terms shall have
the meanings indicated:
The person, firm, or corporation entering into the contract with
the developer for the installation of water pipe, fittings and appurtenances.
The person, firm or corporation proposing to install water lines
in the Town of Somers in conjunction with any land subdivision or site plan,
wherein a present or proposed public right-of-way is utilized or where more
than one lot, parcel of land or family residence will be served.
A professional engineer licensed in the State of New York and duly
appointed by the Town of Somers as its representative for the review of plans
and the inspection of construction.
An authorized representative of the Engineer assigned to make any
and all necessary inspections of the work performed and of materials and equipment
furnished by the contractor.
B.
Other terms. Whenever in the specifications or drawings
the words "directed," "required," "permitted," "ordered," "designated," "prescribed"
or words of like import are used, it shall be understood that a direction,
requirement, permission, order, designation or prescription of the Engineer
is intended, and, similarly, the words "approved," "acceptable," "satisfactory"
or words of like import shall mean approved by or acceptable or satisfactory
to the Engineer, unless otherwise expressly stated.
The developer shall furnish all labor, equipment and material, necessary
to complete the pipeline work. The developer shall:
A.
Cut existing pavements only to the minimum extent necessary.
B.
Excavate the trenches and pits to the required dimensions.
C.
Maintain traffic.
D.
Sheet, brace and support the adjoining ground or structures
where necessary.
E.
Provide for all drainage of groundwater.
F.
Guard the site.
G.
Unload, haul, distribute, lay, test and disinfect the
pipe and accessories.
H.
Replace all damaged drains or other structures.
I.
Backfill the trench and pits.
J.
Restore the roadway surface.
K.
Remove surplus excavated material.
L.
Clean the site of the work.
M.
Test the completed pipeline for pressure and leakage
requirements.
N.
Disinfect the complete pipeline.
O.
Furnish the as-built locations to the town.
All manufactured material shall be certified by the manufacturer to
the Town of Somers as meeting the requirements for that particular class of
material before shipment. All laying, jointing, testing for defects and for
leakage under pressure and disinfection shall be performed in the presence
of the Engineer or his authorized Inspector and shall be subject to approval
of the Engineer before acceptance. Material found during the progress of the
work to have cracks, flaws or other defects may be rejected by the Engineer
or the Inspector, and the developer shall promptly remove such defective material
from the site of the work.
The developer shall provide a survey layout for the pipelines and hydrants
to assure their placement in accordance with the approved plans or as directed
by the Engineer. At the completion of the work the developer shall furnish
a utilities location plat, certified to the Town of Somers by a professional
engineer or land surveyor licensed in New York State. This plat shall show
the size, length and material of construction of all pipelines, valves, hydrants
or other appurtenances, together with their vertical and horizontal location
referenced to monuments, permanent bench marks or other enduring survey reference
marks. The plat shall be of india ink on linen at a scale of one inch equals
50 feet.
A.
Pipe and accessories shall at all times be handled with
care to avoid damage. Whether moved by hand, skidways or hoists, material
shall not be dropped or bumped. The interior and machined ends of all pipe
shall be kept free from dirt and foreign matter at all times.
B.
Pipe shall be handled in such manner as to avoid damage
to the machined ends. Pipe damaged at such points that cannot be repaired
to the Engineer's satisfaction shall be replaced. Valves and hydrants shall
be kept drained and stored before installation in a manner protecting them
from damage due to freezing of trapped water.
All pipe shall be laid and maintained to the required lines and grades.
Fittings, valves and hydrants shall be at the required locations with joints
centered, spigots home and all valve and hydrant stems plumb. No deviation
shall be made from the required line or grade except by approval of the Engineer.
All pipe shall be laid to the depth shown on the contract drawings or
as directed by the Engineer in writing. The depth shall be measured from the
established street grade or the surface of the permanent improvement to the
top of the pipe barrel. The general standard of the Town of Somers shall be
four feet of cover from the top outside of mains.
A.
General. The trench shall be dug to the required alignment
and depth shown on the contract drawings or as directed by the Engineer and
only so far in advance of pipelaying as the Engineer shall permit. The trench
shall be braced and drained when necessary so that workmen may work therein
safely and efficiently.
B.
Width. The trench width at the ground surface may vary
with and depend upon its depth and the nature of the ground encountered. The
minimum clear width of unsheeted or sheared trench measured at the horizontal
diameter of the pipe shall be 32 inches and shall be at least 12 inches clear
of the outside diameter of the barrel of the pipe on each side.
C.
Foundation. The pipe shall be laid on compacted stable soil and upon a bedding layer of backfill in accordance with § A173-21A. Any part of the trench excavated below grade shall be backfilled to grade with thoroughly compacted material approved by the Engineer. When an unstable subgrade condition is encountered and, in the opinion of the Engineer, it cannot support the pipe, an additional depth shall be excavated and refilled to the pipe-foundation grade with crushed stone or other suitable material as required by the Engineer to achieve a satisfactory trench bottom.
D.
Rock excavation. Ledge rock, boulders and large stones
shall be removed to provide 12 inches of clearance to each side of and below
all pipe and accessories. Excavations below subgrade in rock or in boulders
shall be refilled to subgrade with material approved by the Engineer and thoroughly
compacted.
E.
Excavation methods. The use of trench-digging machinery will be permitted except where its operations will cause damage to trees, buildings or existing structures above or below the ground. At such locations hand methods shall be employed to avoid such damage. Wherever necessary to prevent caving, trench excavations in soils, such as sand, gravel and sandy soil, shall be adequately sheeted and braced. Where sheeting and bracing are used, the trench width shall not be less than that specified in Subsection B. As backfill is placed and if sheeting is to be withdrawn, it shall be withdrawn in increments of not more than two feet, and the void left by the withdrawn sheeting shall be filled and compacted.
F.
Provision for public safety. To protect persons from
injury and to avoid property damage, adequate barricades, construction signs,
torches, warning lights and guards as required shall be placed and maintained
during the progress of the construction work until the site is safe for traffic
use.
A.
The pipe shall be laid directly on the compacted trench
bottom or select backfill. Laying on earth mounds or on blocking will not
be allowed.
B.
Before the pipe is lowered into the trench:
(1)
Coupling holes shall be dug of sufficient length, width
and depth to permit assembly and provide a minimum clearance of two inches
between the coupling and undisturbed trench bottom; and
(2)
The trench bottom between coupling holes shall be cut
true and to grade and shaped so as to provide continuous contact of the trench
bottom with the pipe.
Implements, tools and facilities satisfactory to the Engineer shall
be provided and used by the contractor for the safe and efficient execution
of the work. All pipe, fittings, valves, hydrants and accessories shall be
carefully lowered into the trench with suitable equipment in a manner that
will prevent damage to pipe and fittings. Under no circumstances shall pipe
or accessories be dropped or dumped into the trench. Pipe and accessories
shall be inspected for defects prior to their being lowered into the trench.
Any defective, damaged or unsound material shall be repaired or replaced as
directed by the Engineer. All foreign matter or dirt shall be removed from
the interior and machined ends of the pipe and accessories before they are
lowered into position in the trench. Pipe shall be kept clean by means approved
by the Engineer during and after laying. When pipelaying is not in progress,
the open pipe ends shall be closed by a watertight plug or other approved
means to prevent entrance of trench water into the line. Whenever water is
excluded from the interior of the pipe, enough backfill shall be placed on
the pipe to prevent floating. Any pipe that has floated shall be removed from
the trench and relaid as directed by the Engineer. No pipe shall be laid in
wet trench conditions that preclude proper bedding or on a frozen trench bottom
or when, in the opinion of the Engineer, the trench conditions or the weather
are unsuitable for proper installation.
A.
The machined ends of pipe to be jointed, the coupling
grooves and rubber rings shall be cleaned immediately before assembly, and
assembly shall be made as recommended by the manufacturer. Each pipe joint
shall be sealed with a coupling consisting of an asbestos-cement sleeve and
two rubber rings. The position of field-assembled rings shall be checked with
a suitable gauge to verify that they are seated in the required position.
B.
Pipe shall not be deflected either vertically or horizontally
more than the limits recommended by the manufacturer or permitted by the Engineer.
A sleeve shall be cast in the wall of rigid structures at the point
of entry of pipelines to provide flexibility at the wall. To provide additional
flexibility, the pipe at the point of entry into a rigid structure and at
every point of connection to a fitting fastened to thrust-blocking shall have
a laying length of not more than six feet six inches for eight-inch-diameter
pipe or larger and three feet for pipe of lesser diameter.
A.
Each valve, hydrant or fitting which is connected shall
have a profile that provides for a seal, to be made between the machined pipe
end and the bell of the fitting with a rubber ring.
B.
Before valves, hydrants or fittings are laid, all lumps,
blisters and excess coating shall be removed from the bell. The inside of
the bell shall then be wire-brushed, and both the inside of the bell and the
spigot end of the pipe wiped clean and dry.
A.
Bends, tees and reducers shall be lowered into the trench,
inspected, cleaned and jointed as specified above. Reaction or thrust-backing
shall be applied at bends and tees and at points at reducers or in fittings
where changes in pipe diameter occur. The design of concrete thrust-backing
shall be as shown on contract drawings or as directed by the Engineer.
B.
The material of reaction- or thrust-backing shall be
concrete composed of concrete aggregates in accordance with the American Society
for Testing and Materials Designation C 33 and portland cement in accordance
with American Society for Testing and Materials Designation C 150 for portland
cement or Designation C 175 for air-entrained portland cement. The mix shall
not be leaner than one part cement to 2 1/2 parts sand to five parts stone
and shall have a compressive strength of no less than 2,000 pounds per square
inch in 36 hours for high-early-strength cement (Types III or IIIA) and seven
days for standard cement (Types I or IA).
C.
Backing shall be placed between solid ground and the
fitting to be anchored. The area of bearing on the fitting and on the ground
shall in each instance be that required by the Engineer. Unless otherwise
directed by the Engineer, the backing shall be placed so that the pipe and
fitting joints will be accessible for repair.
D.
Metal harness of tie-rods and pipe clamps shall be used
to prevent movement, as shown on the contract drawings or directed by the
Engineer. Steel rods and clamps shall be galvanized or otherwise rustproofed
or painted.
All geared valves and any other valves 10 inches or more in diameter
shall be set in concrete valve pits. The wrench nuts shall be readily accessible
for operation through the manhole opening. Pits shall be constructed in a
manner that will permit minor valve repairs and afford protection of the pipe
against impact or settlement where the pipe passes through the pit walls.
Cast-iron valve boxes shall be firmly supported and shall be kept centered
and plumb over the wrench nut of the gate valve; the box cover shall be flush
with the surface of the finished pavement or another level designated by the
Engineer.
Drainage branches or blowoffs shall be provided as shown on contract
drawings or as directed by the Engineer. Drainage branches or blowoffs shall
not be connected to any sewer, submerged in any stream or installed in any
other manner that with permit back-siphonage into the distribution system.
A.
Setting. Hydrants shall be lowered into the trench, inspected,
joined to the pipe as specified above and reaction- or thrust-backing provided.
Hydrants shall be thoroughly cleaned before they are set.
B.
Location. Hydrants shall be located to provide complete
accessibility and to minimize the possibility of damage from vehicles or injury
to pedestrians. The following provisions shall govern, unless other instructions
are issued by the Engineer:
(1)
The bowl of any hydrant placed behind the gutter shall
be set so that no portion of the hydrant or hose nozzle caps on the street
side shall be less than 12 inches nor more than 24 inches from the back of
the gutter.
(2)
All hydrants shall stand plumb.
(3)
Pumper nozzles shall be at right angles to and facing
the curb.
(4)
Hose nozzles shall parallel the roadway, except that
hydrants with two hose nozzles, 90º apart, shall be set so that the nozzles
face the roadway at an angle of 45º.
(5)
Nozzles shall be at least 12 inches above the ground.
C.
Connection to main. Each hydrant shall be connected to
the main with a six-inch pipe and, except where waived by the Engineer, shall
be controlled by an independent six-inch gate valve.
D.
Drainage. Hydrants shall be set with a drainage pit two
feet in diameter and two feet deep below each hydrant. The pit shall be fixed
compactly with coarse gravel or broken stone mixed with coarse sand under
and around the bowl of the hydrant to a level six inches above the waste opening.
E.
Reaction- or thrust-backing. A reaction- or thrust-backing
shall be provided at the bowl of each hydrant and shall be so placed as not
to obstruct the drainage outlet of the hydrant, or, alternately, as directed
by the Engineer, the bowl of the hydrant shall be tied to the pipe main with
rods. The size and shape of concrete thrust-backing or the number and size
of the tie rods shall be as shown on the contract drawings and approved by
the Engineer.
F.
Hydrants installed on pipelines connected to a system
not fully operative for fire flows shall be painted with three field coats
of white paint. Hydrants connected to operative fire-rated systems shall be
painted with two field coats of red, orange or green in accord with the American
Water Works Association Standard C 502-64, Appendix B.
Standard plugs shall be inserted into the bells of all dead-end fittings.
Spigot ends of fittings and plain ends of pipe shall be capped. A concrete
reaction- or thrust-backing shall be provided at all dead ends of pipe that
are capped or plugged. Capped or plugged outlets to fittings in the sizes
indicated on the contract drawings or as directed by the Engineer shall be
tied to the fittings with clamps and tie-rods. The number and size of rods
shall be as specified, and thrust-blocking shall be provided.
A.
General. The following procedure is based on the assumption
that the pressure and leakage tests will be performed at the same time; however,
separate tests may be made, if desired. If separate tests are made, the pressure
test shall be made first, the duration of the pressure test may be reduced
to one hour, and the test pressure for the leakage test may be reduced to
the maximum working pressure that will occur on the portion of the line being
tested. The duration of the leakage test shall be two hours unless otherwise
directed by the Engineer.
B.
Preparation. After the pipeline has been laid, it shall
be slowly filled with water for a minimum of 24 hours and then subjected to
a hydrostatic-pressure test. Unless otherwise specified, the test pressure
shall be 50% greater than the operating-pressure gradient at the lowest elevation
of the system. When, in the opinion of the Engineer, local conditions require
that the trenches be backfilled immediately after the pipe has been laid,
the pressure test may be made after backfilling has been completed but before
placement of permanent paving. Except where otherwise directed the joints
shall be exposed at the time of the test. A test shall be made only after
backfilling has been completed between joints to at least a one-foot depth
over all pipes being tested and for the full width of the trench. Also, these
tests shall not be made until three days after the last concrete thrust- or
reaction-backing has been cast with high-early-strength cement or at least
seven days after the last concrete thrust- or reaction-backing has been cast
with standard cement. The Engineer may, however, reduce the required curing
time for thrust- or reaction-backing concrete at specific locations based
on a determination by elastic rebound testing that the concrete has attained
a strength of at least 2,000 pounds per square inch.
C.
Procedure.
(1)
Each section of pipeline shall be slowly filled with
water, and the specified test pressure shall be applied by means of a pump
connected to the pipe in a manner satisfactory to the Engineer. The pump,
pipe connection and all necessary apparatus, including gauges, shall be furnished
by the developer. The developer shall furnish calibration data on all gauges
used, certified by an independent supplier or laboratory, satisfactory to
the Engineer.
(2)
During the filling of the pipe and before the application
of the specified test pressure, all air shall be expelled from the pipeline
by means of taps at points of highest elevation. After completion of the test,
the taps shall be tightly plugged, unless otherwise specified. During the
test, all exposed pipe, fittings, valves, hydrants and asbestos-cement couplings
shall be carefully examined. Any joint at which the accumulated leakage exceeds
the rate specified below shall be rejected. All cracked or defective elements
shall be removed and replaced. The test shall be repeated as necessary until
the results are satisfactory to the Engineer.
D.
Overall leakage. No pipe installation will be accepted
until or unless the leakage for the section of line tested is less than the
rate of leakage specified by Westchester County, New York, for mechanical
and push-on joints (50 gallons per day per mile of pipe per inch of nominal
diameter). If the test leakage in any section is greater than that permitted,
the developer shall locate and repair the defective joints until the leakage
is within the permitted allowance.
A.
Materials. Backfill of undercut areas shall be made with
crushed stone or gravel of the following gradation: 100% passing a two-and-one-half-inch
sieve, and 90% retained on a one-fourth-inch sieve. Undercut backfill shall
be placed to the depth as ordered by the Engineer. Backfill from six inches
below the bottom outside of the pipe to 12 inches above the top shall pass
the requirements for New York State Department of Transportation Item 2 EF-B.
B.
Backfilling before tests. Backfill material shall be
approved by the Engineer and shall be unfrozen and free from rock, lumps of
clay, large stones, boulders or other unsuitable substances. Backfill shall
be deposited in the trench uniformly at both sides of the pipeline for the
full width of the trench up to the horizontal diameter of the pipeline. This
backfill material shall be tamped in layers four inches thick after compaction
and shall be sufficiently damp to permit thorough compaction under and on
each side of the pipe.
C.
Backfill procedure after tests. On completion of pressure
and leakage tests, exposed couplings shall be covered with approved backfill,
hand-placed and compacted to a depth of 12 inches above the top of the pipe
and couplings. The balance of backfill may be machine placed, but shall contain
no stones more than six inches in their largest dimension. The backfill mixture
shall not contain more than 25% stones regardless of the location of the trench.
Item 2 EF-B graded material shall be compacted to a density of 95%. Trenches
under roadway, shoulder or gutter pavement shall be compacted to a density
of 95%. Trenches in the right-of-way of a road or driveway which are not under
pavement shall be backfilled to a compaction density of 90%. Density shall
be determined by the American Association of State Highway Officials Method
T 99 for Compaction and Density of Soils. Trenches outside of the rights-of-way
shall be backfilled to a compacted density of 90% for a depth of 12 inches
over the top outside of the pipe.
D.
Pipeline indicators. To indicate the presence of the
pipes and minimize the probability of accidental breakage by any future construction
operations, the developer shall place an indicator to show the presence of
the pipeline. This shall consist of two runs of blue colored nonadhesive plastic
tape (surveyors' plastic flagging). The tapes shall be placed in the trench
backfill approximately 12 inches apart and centered on the pipe at an elevation
approximately 18 inches above the top outside of the pipe.
Before the pipeline is placed in service and before certification of
completion by the Engineer, it will be required that all new water systems,
extensions to existing systems, valved sections of extensions, replacements
in the existing system and any exposed section of the existing system be disinfected
in accordance with American Water Works Association Standard C 601, Disinfection
of Water Mains, and to the satisfaction of the Engineer. Segments of the system
which can be isolated may be disinfected and, if otherwise satisfactorily
completed, will be certified.
The above certification shall not act to relieve the developer of his
responsibility to protect and maintain the water system described above until
such time as the Town Board of Somers shall, on recommendation of the Planning
Board, accept and receive the system, in whole or in part.
