It is the intent of these specifications to
outline the minimum acceptable requirements governing the construction
of and materials used in water and sewer mains which will connect
with the Ithaca water and sewer systems, whether constructed for the
city, either by city forces under the direction of the Superintendent
of Public Works or by a contractor under an agreement with the city,
or constructed for private individuals, corporations or water districts
who may have received a permit to connect with the city system and
which water and sewer mains are to be built by themselves or by contractors
under an agreement with them.
No connections to any mains in the water or
sewer system may be made until such connections are authorized by
the Board of Public Works and the plans for the water or sewer main
extension are approved by the Board of Public Works.
All work done on water and/or sewer main extensions
connecting to the Ithaca systems must conform to these specifications
and must be done under the supervision and inspection of the Superintendent
of Public Works or under such inspection as may be otherwise ordered
by the Board of Public Works. The term "inspector" hereinafter used
will mean the duly designated representative of the Board of Public
Works.
The rules and regulations of the Board of Public
Works in the preceding Articles of this chapter governing the installation
and use of service lines and mains and the New York State Uniform
Fire Prevention and Building Code applicable to plumbing shall be
considered a part of these specifications and shall govern such conditions
as are not herein specifically described.
A.
Description. The trench shall be excavated to full
depth and grade for a distance of at least 50 feet in advance of pipelaying
but not more than one average day's pipelaying in advance of the work.
The trench shall be so braced and drained that the workers may work
therein safely and efficiently. It is essential that the discharge
from the trench dewatering pumps be conducted to natural drainage
channels, drains or storm sewers.
B.
Width of trench.
(1)
The width of the trench shall be ample to permit the
pipe to be laid and jointed properly and the backfill to be placed
and compacted as specified. Trenches shall be of such extra width,
when required, as will permit the convenient placing of timber supports,
sheeting and bracing, and handling of fittings.
(2)
The minimum width shall be sufficient to give a clearance
of at least eight inches on either side of the barrel of the pipe.
C.
Bell holes. Bell holes shall be provided at each joint
to permit the jointing to be made properly.
D.
Pipe clearance in rock. Ledge rock, boulders and large
stones shall be removed to provide a clearance of at least six inches
below and eight inches on each side of all pipe and fittings.
E.
Excavation to grade.
(1)
The trench shall be excavated to the depth required
so as to provide a uniform and continuous bearing and support for
the pipe on solid and undisturbed ground at every point between bell
holes. Any part of the bottom of the trench excavated below the specified
grade shall be corrected with approved material and thoroughly compacted
as directed by the inspector. The finished grade shall be prepared
accurately by means of hand tools.
(2)
The subgrade beneath the center line of the pipe shall
be finished to within 0.03 foot of a straight line between pipe joints
or batter boards. All tolerances shall be above specified grade.
F.
Excavation in poor soil or rock.
(1)
Where the bottom of the trench at subgrade is found
to be unstable or to include ashes, cinders, all types of refuse,
vegetable or other organic material, large pieces or fragments of
inorganic material, or rock, which, in the judgment of the inspector,
should be removed, the contractor shall excavate and remove such unsuitable
material to the width and depth ordered by the inspector. Before the
pipe is laid, the subgrade shall be made by backfilling with an approved
material in three-inch uncompacted layers. The layers shall be thoroughly
tamped as directed by the inspector so as to provide a continuous
bearing and support for the pipe at every point between the bell holes.
The finished subgrade shall be prepared accurately by means of hand
tools.
(2)
The subgrade beneath the center line of the pipe shall
be finished to within 0.03 foot of a straight line between bell holes
or batter boards, and all tolerances shall be above the specified
grade.
G.
Special foundation in poor soil. Where the bottom
of the trench at subgrade is found to consist of material which is
unstable to such a degree that, in the opinion of the inspector, it
cannot be removed and replaced with an approved material thoroughly
compacted in place to support the pipe properly, the contractor shall
construct a foundation for the pipe consisting of piling, timber or
other materials, in accordance with plans approved by the Board of
Public Works.
H.
Blasting. Blasting for excavation will be permitted
only after securing the approval of the inspector and only when proper
precautions are taken for the protection of persons or property. The
hours of blasting will be fixed by the inspector. Any damage caused
by blasting shall be repaired by the contractor at his/her expense.
The contractor's methods of procedure shall conform to state laws
and city ordinances and local laws.
I.
Braced and sheeted trenches.
(1)
Open-cut trenches shall be sheeted and braced as required
by any governing state laws and as may be necessary to protect life,
property or the work. When close sheeting is required, it shall be
so driven as to prevent adjacent soil from entering the trench either
below or through such sheeting. Where sheeting and bracing are used,
the trench width shall be increased accordingly.
(2)
The inspector reserves the right to order the sheeting
driven to the full depth of the trench or to such additional depths
as may be required for the protection of the work. Where the soil
in the lower limits of a trench has the necessary stability, the inspector,
at his/her discretion, may permit the contractor to stop the driving
of sheeting at some designated elevation above the trench bottom.
The granting of permission by the inspector, however, shall not relieve
the contractor in any degree from his/her full responsibility under
the contract.
(3)
Sheeting and bracing which have been ordered left
in place must be removed for a distance of three feet below the established
street grade or the existing surface of the street, whichever is lower.
Trench bracing, except that which must be left in place, may be removed
when the backfilling has reached the respective levels of such bracing.
Sheeting, except that which has been left in place, may be removed
after the backfilling has been completed or has been brought up to
such an elevation as to permit its safe removal. Sheeting and bracing
may be removed before flushing the trench but only in such manner
as will ensure the adequate protection of the completed water and/or
sewer structures and prevent the disturbance of adjacent ground.
J.
Care of surface materials for reuse. All surface materials
which, in the opinion of the inspector, are suitable for reuse in
restoring the surface shall be kept separate from the general excavation
material, as directed by the inspector.
K.
Piling excavated material. All excavated material
shall be piled in a manner that will not endanger the work and that
will avoid obstructing sidewalks and driveways. Hydrants under pressure,
valve pit covers, valve boxes, curb stop boxes, fire and police call
boxes or other utility controls shall be left unobstructed and accessible
until the work is completed. Gutters shall be kept clear or other
satisfactory provisions shall be made for street drainage, and natural
watercourses shall not be obstructed.
L.
Trenching by hand methods. Hand methods for excavation
shall be employed in locations where obstructions are shown on drawings
or where, in the opinion of the inspector, property can best be protected
by digging by hand. In other locations, the contractor may use trench-digging
machinery.
M.
Barricades, guards and safety provisions. To protect
persons from injury and to avoid property damage, adequate barricades,
construction signs, torches, lanterns and guards, as required, shall
be placed and maintained during the progress of the construction work
and until it is safe for traffic to use the highway. All material
piles, equipment and pipe which may serve as obstructions to traffic
shall be enclosed by fences or barricades and shall be protected by
proper lights when the visibility is poor. The rules and regulations
of the local authorities respecting safety provisions shall be observed.
N.
Maintenance of traffic and closing of streets.
(1)
The contractor shall carry on the work in a manner
which will cause the least interruption to traffic and may close to
travel not more than two consecutive blocks upon the specific permission
of the city, including the cross street intersected. Where traffic
must cross open trenches, the contractor shall provide suitable bridges
at street intersections and driveways.
(2)
The contractor shall post, where directed by the inspector,
suitable signs indicating that a street is closed and necessary detour
signs for the proper maintenance of traffic.
O.
Structure protection. Temporary support, adequate
protection and maintenance of all underground and surface structures,
drains, sewers and other obstructions encountered in the progress
of the work shall be furnished by the contractor at his/her expense
and under the direction of the inspector. The structures which may
have been disturbed shall be restored upon completion of the work.
P.
Protection of property and surface structures. Trees,
shrubbery, fences, poles and all other property and surface structures
shall be protected unless their removal is shown on the drawings or
authorized by the inspector. When it is necessary to cut roots and
tree branches, such cutting shall be done under the supervision of
the inspector.
A.
Backfill material. All backfill material shall be
free from cinders, ashes, refuse, vegetable or organic material, boulders,
rocks or stones or other material which, in the opinion of the inspector,
is unsuitable. However, from one foot above the top of the pipe to
the subgrade of the pavement, material containing stones up to eight
inches in their greatest dimension may be used, unless specified otherwise
herein.
B.
Use of excavated material as backfill. When the type
of backfill material is not indicated on the drawings or specifications,
the contractor may backfill with the excavated material, provided
that such material consists of loam, clay, sand, gravel or other material
which, in the opinion of the inspector, is suitable for backfilling.
C.
Sand or gravel backfill. Where sand or gravel backfill
is not indicated on the drawings or specified herein and, in the opinion
of the inspector, should be used in any part of the work, the contractor
shall furnish and backfill with sand or gravel as directed.
D.
Backfilling under pipe. All trenches shall be backfilled
by hand, from the bottom of the trench to the center line of the pipe,
with sand, gravel or other approved material placed in layers of three
inches and compacted by tamping. Backfilling material shall be deposited
in the trench for its full width on each side of the pipe, fittings
and appurtenances simultaneously.
E.
Backfilling over pipe.
(1)
From the center line of the pipe, fittings and appurtenances
to a depth of one foot above the top of the pipe, the trench shall
be backfilled by hand or by approved mechanical methods. The contractor
shall use special care in placing this portion of the backfill so
as to avoid injuring or moving the pipe.
(2)
The backfill material from the center line of the
pipe to one foot above the pipe shall consist of approved excavated
material which shall be placed in three-inch layers and compacted
by tamping.
F.
Backfilling in freezing weather. Backfilling shall
not be done in freezing weather, except by permission of the inspector,
and it shall not be made with frozen material. No fill shall be made
where the material already in the trench is frozen.
G.
Backfill sand. All sand used for backfill shall be
a natural bank sand, graded from fine to coarse, not lumpy or frozen
and free from slag, cinders, ashes, rubbish or other material which,
in the opinion of the inspector, is objectionable or deleterious.
It shall not contain a total of more than 10% by weight of loam and
clay, and all material must be capable of being passed through a three-fourths-inch
sieve. Not more than 5% shall remain on a No. 4 sieve.
H.
Backfill gravel. Gravel used for backfill shall consist
of natural bank gravel having durable particles graded from fine to
coarse in a reasonably uniform combination, with no boulders or stones
larger than two inches in size. It shall be free from slag, cinders,
ashes, refuse or other deleterious or objectionable materials. It
shall not contain excessive amounts of loam and clay and shall not
be lumpy or frozen. No more than 15% shall be finer than a No. 200
sieve. Backfill gravel shall be used in the top 18 inches of backfill
of all ditches in city streets.
A.
Materials to be used.
(1)
Pipe and fittings.
(a)
All pipelines four inches in diameter and larger
shall be bell-and-spigot, tar-coated, cement-lined, centrifugally
cast pipe to meet American Water Works Association specifications,
the class of pipe used to be determined by the operating pressure
and conditions of the line. All fittings shall be Class D, tar-coated
long pattern to meet American Water Works Association specifications.
(b)
The use of mechanical joints and rubber-joint
cast-iron pipe will be allowed by approval of the Board of Public
Works.
(2)
Valves. Main line valves shall be Darling hub-end
valves of the type used by the City of Ithaca. Valves shall open left
(counterclockwise).
(3)
Hydrants.
(a)
Hydrants shall be Darling B-50-B, five-inch
hydrants of the type used by the City of Ithaca. Hose nozzle threads
shall be City of Ithaca standard. Hydrants shall have a two-and-one-half-inch
hose nozzle and one four-and-one-half-inch steamer nozzle.
(b)
The two-and-one-half-inch hose nozzles shall
be the City of Ithaca standard, measuring three inches outside diameter
to the top of the thread with 7 1/2 threads to the inch. The
four-and-one-half-inch steamer nozzle shall be national standard measuring
5 3/4 inches outside diameter at the top of the thread and threaded
four threads per inch.
(4)
Valve boxes. Valve boxes shall be the Buffalo screw-type
roadway box with the cover marked "water."
(5)
Manholes.
(a)
Manholes may be built of concrete masonry of
1-2-4 concrete using tight smooth forms or standard cement manhole
blocks formed especially for four-foot manholes.
(b)
Manholes may be built of masonry using hard-pressed
brick. Every fifth course of brick shall be laid as stretchers, the
remainders to be headers. Every brick shall have full mortar joints
on the bottom and sides which shall be formed at one operation by
placing sufficient mortar on the bed and forcing the brick into it.
Horizontal joints shall not exceed 3/8 inch, and vertical joints on
the inside of manholes shall not exceed 1/4 inch. Joints on the inside
face are to be carefully rubbed full and struck as a manhole is built
up. In wet trenches, water shall be kept drained away from manholes
until the concrete is set.
(c)
No backfilling shall be done for 24 hours after
completion of the manhole.
(d)
In freezing weather, customary precautions of
heating materials and after-protection shall be followed.
[1]
Steps. Steps of cast-iron or of galvanized wrought
iron 3/4 inch in diameter shall be securely placed in the inside of
the manhole during construction not more than 18 inches apart.
[2]
Diameter. Manholes five feet deep or less shall
have a minimum inside diameter of four feet at the bottom. Manholes
10 feet deep shall be at least five feet in inside diameter, and at
intermediate depths the diameter shall be in proportion.
[3]
Frames and covers. Manhole covers shall be set
to the grade given by the inspector. Covers of manholes in streets
shall correspond to the type used and approved by the City of Ithaca
in 1932, the frame and cover to weigh not less than 480 pounds. The
depth of the frame shall be eight inches, and the diameter of the
cover shall be 24 inches. Manholes in parking areas where no traffic
can be expected may use covers of lightweight type used in the City
of Ithaca prior to 1932. The weight of the frame and cover shall be
not less than 245 pounds, and the depth of the frame shall be four
inches.
B.
Inspection of material.
(1)
Field inspection. All pipe and accessories shall be
laid, jointed and tested under pressure for defects and leakage in
the manner specified and in the presence of and as approved by the
inspector.
(2)
Disposition of defective material. All material found
during the progress of the work to have cracks, flaws or other defects
will be rejected by the inspector. All defective materials shall be
promptly removed from the site.
C.
Handling of materials.
(1)
Hauling. Cast-iron pipe, fittings, valves, hydrants
and accessories shall be loaded and unloaded by lifting with hoists
or skidding so as to avoid shock or damage. Under no circumstances
shall such materials be dropped. Pipe handled on skidways shall not
be skidded or rolled against pipe already on the ground.
(2)
At the site of the work. In distributing the material
at the site of the work, each piece shall be unloaded opposite or
near the place where it is to be laid in the trench.
(3)
Care of pipe coating and lining. Pipe shall be so
handled that the coating and lining will not be damaged. If, however,
any part of the coating or lining is damaged, the repair shall be
made in a manner satisfactory to the inspector.
D.
Alignment and grade.
(1)
General.
(a)
The water main shall be laid and maintained
to the required lines and grades, with fittings, valves and hydrants
at the required locations, spigots centered in bells and all valves
and hydrant stems plumb.
(2)
Depth of pipe. The top of the pipe shall be laid to
a minimum depth of four feet below the established grade. Any variations
therefrom shall be made only with the approval of the inspector.
E.
Laying.
(1)
Handling of water main material into the trench. Proper
implements, tools and facilities satisfactory to the inspector shall
be provided and used for the safe and convenient prosecution of the
work. All pipes, fittings, valves and hydrants shall be carefully
lowered into the trench piece by piece by means of a derrick, ropes
or other suitable tools or equipment in such manner as to prevent
damage to water main materials and protective coatings and linings.
Under no circumstances shall water main materials be dropped or dumped
into the trench.
(2)
Hammer test. The pipe and fittings shall be inspected
for defects and, while suspended above grade, shall be rung with a
light hammer to detect cracks.
(3)
Cleaning pipe and fittings. All lumps, blisters and
excess tar-coat coating shall be removed from the bell-and-spigot
end of each pipe, and the outside of the spigot and the inside of
the bell shall be wire-brushed and wiped clean and dry and free from
oil and grease before the pipe is laid.
(4)
Laying pipe.
(a)
Every precaution shall be taken to prevent foreign
material from entering the pipe while it is being placed in the line.
If the pipelaying crew can not put the pipe into the trench and in
place without getting earth into it, the inspector may require that,
before lowering the pipe into the trench, a heavy, tightly woven canvas
bag of suitable size shall be placed over each end and left there
until the connection is to be made to the adjacent pipe. During laying
operations, no debris, tools, clothing or other materials shall be
placed in the pipe.
(b)
After placing a length of pipe in the trench,
the spigot end shall be centered in the bell and the pipe forced home
and brought to correct line and grade. The pipe shall be secured in
place with approved backfill material tamped under it except at the
bells. Pipe and fittings which do not allow a sufficient and uniform
space for joints shall be removed and replaced with pipe and fittings
of proper dimensions to ensure such uniform space. Precautions shall
be taken to prevent dirt from entering the joint space.
(c)
At times when pipelaying is not in progress,
the open ends of pipe shall be closed by a watertight plug or other
means approved by the inspector. Joints of pipe in the trench which
cannot be poured shall be caulked with packing to make them as watertight
as possible. This provision shall apply during the noon hour as well
as overnight. If water is in the trench, the seal shall remain in
place until the trench is pumped completely dry.
(5)
Cutting pipe.
(a)
The cutting of pipe for inserting valves, fittings
or closure pieces shall be done in a neat and professional manner
without damage to the pipe or cement lining and so as to leave a smooth
end at right angles to the axis of the pipe.
(b)
When machine-cutting is not available for cutting
pipe 20 inches in diameter or larger, the electric-arc cutting method
will be permitted using a carbon or steel rod. Only qualified and
experienced workers shall be used on this work.
(c)
The flame-cutting of pipe by means of an oxyacetylene
torch shall not be allowed.
(6)
Bell ends to face direction of laying. Pipe shall
be laid with bell ends facing in the direction of laying unless directed
otherwise by the inspector.
(7)
Permissible deflection at joints. Wherever it is necessary
to deflect pipe from a straight line, either in the vertical or horizontal
plane, to avoid obstruction or plumb stems or where long-radius curves
are permitted, the amount of deflection allowed shall not exceed that
required for satisfactory caulking of the joint and shall be approved
by the inspector.
|
Maximum Deflection Length of:
|
Approximate Radius of Curve
With Pipe Produced by Succession of Joints with Pipe Leads of:
| |||||||
|---|---|---|---|---|---|---|---|---|
|
Pipe Diameter
(inches)
|
Joint Opening
|
16 Feet
|
18 Feet
|
20 Feet
|
16 Feet
|
18 Feet
|
20 Feet
| |
|
4
|
0.41
|
14.8
|
16.7
|
18.5
|
208
|
234
|
260
| |
|
6
|
0.58
|
14.8
|
16.7
|
18.5
|
208
|
234
|
260
| |
|
8
|
0.65
|
12.9
|
14.6
|
16.2
|
238
|
268
|
297
| |
|
10
|
0.75
|
12.4
|
14.0
|
15.5
|
248
|
279
|
310
| |
|
12
|
0.75
|
10.5
|
11.9
|
13.2
|
292
|
327
|
363
| |
|
16
|
0.75
|
7.9
|
8.8
|
9.7
|
390
|
440
|
488
| |
(8)
Unsuitable conditions for laying pipe. No pipe shall
be laid in water or when, in the opinion of the inspector, the trench
conditions are unsuitable.
F.
Jointing.
(1)
Yarning or packing material. Yarning or packing material
shall be molded or tubular rubber rings. The above material shall
be handled with care in order to prevent contamination and shall be
dry when put into place in the joint. The material shall be free of
oil, tar or greasy substances.
(2)
Placing of yarning material. The yarning material
shall be placed around the spigot end of the pipe and shall be of
proper dimensions to center the spigot in the bell. When the spigot
is shoved home, the yarning material shall be driven tightly against
the inside base or hub of the bell with a suitable yarning tool.
(3)
Depth of jointing material. For lead joints, a space
not less than 2 1/4 inches in depth shall be left in the bell
in pipe having a nominal diameter of 20 inches or less; 2 1/2
inches in twenty-four-, thirty- and thirty-six-inch pipe; and three
inches in pipe larger than 36 inches.
(4)
(5)
Heating and pouring of lead. Lead shall be heated
in a melting pot kept in easy reach of the joint to be poured so that
the molten metal will not be chilled in being carried from the melting
pot to the joint and shall be brought to a proper temperature so that,
when stirred, it will show a rapid change of color. Before pouring,
all scum shall be removed. Each joint shall be made in one continuous
pouring, filling the entire joint space with solid lead. Spongy or
imperfectly filled joints shall be burned out and repoured.
(6)
Position of joint runner. The joint runner shall fit
snugly against the face of the bell, and the outside of the pipe shall
be dammed with clay to form a pouring lip to provide for filling the
joint flush with the face and to the top of the bell.
(7)
Caulking lead joints. After the lead has cooled to
the temperature of the pipe, lead joints shall be caulked with pneumatic
or hand tools operated by competent workers until such joints are
thoroughly compacted and watertight. The finished joint shall show
a hard and even hammered surface overall. Care should be taken not
to overstrain the bells during caulking.
G.
Setting valves and fittings.
(1)
General. Valves, fittings, plugs and caps shall be
set and jointed to pipe in the manner heretofore specified for cleaning,
laying and jointing pipe.
(2)
(a)
A valve box or manhole shall be provided for
every valve.
(b)
The valve box shall not transmit shock or stress
to the valve and shall be centered plumb over the operating nut of
the valve, with the box cover flush with the surface of the ground
or such other level as may be directed.
(c)
Where valves are in manholes, the operating
nut shall be readily accessible for operation through the opening
in the manhole, which shall be set flush with the surface of the finished
pavement. Manholes shall be so constructed as to permit minor repairs
and afford protection to the valve and pipe from impact where they
pass through the manhole wall.
(3)
Drainage of mains.
(a)
Mains shall be drained through drainage branches
or blowoffs to dry wells from which the water can be pumped. Drainage
branches, blowoffs, air vents and appurtenances shall be provided
with gate valves and shall be located and installed as shown on the
plans.
(b)
Drainage branches or blowoffs shall not be connected
to any sewer, submerged in any stream or be installed in any other
manner that will permit backsiphonage into the distribution system.
H.
Setting hydrants.
(1)
Location.
(a)
Hydrants shall be located as shown or as directed
and in a manner to provide complete accessibility and also in such
a manner that the possibility of damage from vehicles or injury to
pedestrians will be minimized.
(b)
When placed behind the curb, the hydrant barrel
shall be set so that no portion of the pumper or hose nozzle cap will
be less than six inches nor more than 12 inches from the gutter face
of the curb.
(c)
When set in the lawn space between the curb
and the sidewalk or between the sidewalk and the property line, no
portion of the hydrant or nozzle cap shall be within six inches of
the sidewalk.
(2)
Position. All hydrants shall stand plumb and shall
have their nozzles parallel with or at right angles to the curb, with
the pumper nozzle facing the curb, except that hydrants having two
hose nozzles 90° apart shall be set with each nozzle facing the
curb at an angle of 45°. Hydrants shall be set to the established
grade, with nozzles at least 12 inches above the ground, as shown
or as directed by the inspector.
(3)
Connection to main. Each hydrant shall be connected
to the main with a six-inch cast-iron branch controlled by an independent
six-inch gate valve, except as otherwise directed.
(4)
Hydrant drainage in pervious soil. Wherever a hydrant
is set in soil that is pervious, drainage shall be provided at the
base of the hydrant by placing coarse gravel or crushed stone mixed
with coarse sand from the bottom of the trench to at least six inches
above the waste opening in the hydrant and to a distance of one foot
around the elbow. No drainage system shall be connected to the sewer.
(5)
Hydrant drainage in impervious soil. Whenever a hydrant
is set in clay or other impervious soil, a drainage pit two feet in
diameter and three feet deep shall be excavated below each hydrant
and filled compactly with coarse gravel or crushed stone mixed with
coarse sand under and around the elbow of the hydrant and to a level
of six inches above the waste opening.
I.
Anchorage.
(1)
Anchorage for hydrants. The bowl of each hydrant shall
be well braced against unexcavated earth at the end of the trench
with stone or slabs or concrete backing.
(2)
Anchorage for plugs, caps, tees and bends. All plugs,
caps, tees and bends deflecting 22 1/2° or more on mains
eight inches in diameter or larger shall be provided with a reaction
backing.
(3)
Reaction backing. Reaction backing shall be concrete
of a mix not leaner than one cement to 2 1/2 sand to five stone
and having a compressive strength of not less than 2,000 pounds per
square inch at 28 days. Backing the area of bearing on the pipe and
on the ground in each instance shall be that shown or directed by
the inspector. The backing shall, unless otherwise shown or directed,
be so placed that the pipe and fitting joints will be accessible for
repair.
J.
Hydrostatic tests.
(1)
Pressure test. After the pipe has been laid and partially
backfilled as directed by the inspector, all newly laid pipe or any
valved section thereof shall be subject to a hydrostatic pressure
equal to a pressure 50% greater than the computed working pressure
of the section under test based on the lowest point in the section
under test and corrected to the elevation of the test gauge.
(2)
Duration of pressure test. The duration of each pressure
test shall be at least one hour.
(3)
Procedure. Each valved section of pipe shall be slowly
filled with water, and the specified test pressure, based on the elevation
of the lowest point of the line or section under test and corrected
to the elevation of the test gauge, shall be applied by means of a
pump connected to the pipe in a manner satisfactory to the inspector.
(4)
Expelling air before test. Before applying the specified
test pressure, all air shall be expelled from the pipe. If hydrants
or blowoffs are not available at high places, taps at points of highest
elevation shall be made before the test is made and plugs inserted
after the test has been completed.
(5)
Examination under pressure. All exposed pipes, fittings,
valves, hydrants and joints shall be carefully examined during the
open-trench test. Joints showing visible leaks shall be recaulked
until tight. Any cracked or defective pipe, fittings, valves or hydrants
discovered in consequence of this pressure test shall be removed and
replaced with sound material, and the test shall be repeated until
satisfactory to the inspector.
(6)
Leakage test.
(a)
A leakage test shall be conducted after the
pressure test has been satisfactorily completed. The duration of each
leakage test shall be two hours; and during the test, the main shall
be subject to a pressure equal to the computed working pressure of
the lowest point in the section and corrected to gauge elevation,
except that the test pressure shall be a minimum of 100 pounds per
square inch in the lowest point in the section.
(b)
"Leakage" is defined as the quantity of water
to be supplied into the new laid pipe or any valved section thereof
necessary to maintain the specified leakage test pressure after the
pipe has been filled with water and the air expelled.
(c)
No pipe installation will be accepted until
the leakage is less than the number of gallons per hour as determined
by the formula:
|
L = ND ** P/1,850
| ||||
|
Where
| ||||
|
L
|
=
|
The allowable leakage in gallons per hour.
| ||
|
N
|
=
|
The number of joints in the length of pipe tested.
| ||
|
D
|
=
|
The normal diameter of the pipe in inches.
| ||
|
P
|
=
|
The average test pressure during the leakage
test in pounds per square inch gauge.
| ||
(7)
Variation from permissible leakage. Should any test of pipe laid disclose leakage greater than that specified in Subsection J(6) of this section, the defective joints shall be located and repaired until the leakage is within the specified allowance.
(8)
Time for making test of pipe.
(a)
Lead-jointed pipe may be subjected to hydrostatic
pressure and inspected and tested for leakage at any convenient time
after the trench has been partially backfilled, except at the joints.
(b)
Where any section of a main is provided with
concrete reaction backing, the hydrostatic pressure test shall not
be made until at least five days have elapsed after the concrete reaction
backing was installed. If high-early-strength cement is used in the
concrete reaction backing, the hydrostatic pressure test shall not
be made until at least two days have elapsed.
(9)
Interruption of service. No valve or other control
on the existing system shall be operated for any purpose by the contractor.
The city will operate all valves, hydrants, blowoffs and curb stops.
K.
Disinfection.
(1)
Form of chlorine and means of application. Before
being placed in service, all new water distribution systems and repaired
portions of or extensions to existing systems shall be chlorinated.
If the available water is more alkaline than pH eight, the holding
time in the main shall be increased at the discretion of the Engineer.
(2)
Form of applied chlorine. Any of the following methods
of procedure (arranged in order of preference) shall be followed,
subject to the approval of the Engineer:
(3)
Liquid chlorine. A chlorine gas-water mixture shall
be applied by means of a solution-feed chlorinating device, or, if
approved by the Engineer, the dry gas may be fed directly through
proper devices for regulating the rate of flow and providing effective
diffusion of the gas into the water within the pipe being treated.
Chlorinating devices for feeding solutions of the chlorine gas or
the gas itself must provide means for preventing the backflow of water
into the chlorine cylinder.
(4)
Chlorine-bearing compounds in water. On approval of
the Engineer, a mixture of water and a chlorine-bearing compound of
known chlorine content may be substituted as an alternative for liquid
chlorine.
(a)
Chlorine-bearing compounds. The chlorine-bearing
compounds which may be used are:
(b)
Proportions of mixtures. A five-percent solution
of the powder shall be prepared, consisting of 5% of powder to 95%
of water by weight, due attention being given to the chlorine content
of the product used. This calcium hypochlorite or chlorinated lime
and water mixture, first made into a paste and then thinned to a slurry
with clean water, shall be injected or pumped into the newly laid
pipe after preliminary flushing. If sodium hypochlorite is used, mix
the solution as purchased with water to obtain the desired concentration
of chlorine and feed into the pipe under treatment in the same manner
as is used for feeding other hypochlorites.
(5)
Point of application. The preferred point of application
of the chlorinating agent shall be at the beginning of the pipeline
extension or any valved section of it and through a corporation stop
inserted by the owner (except in new distribution system) in the top
of the newly laid pipe. The water injector for delivering the chlorine-bearing
water into the pipe should be supplied from a tap on the pressure
side of the gate valve controlling the flow into the pipeline extension.
In a new system, application of chlorine may be made advantageously
at the pumping station, the elevated tank, the standpipe or the reservoir.
When properly cleaned first, these units are thus chlorinated adequately.
(6)
Rate of application. Water from the existing distribution
system or other source of supply shall be controlled so as to flow
slowly into the newly laid pipeline during the application of chlorine.
The rate of chlorine mixture flow shall be in such proportion to the
rate of water entering the pipe that the chlorine dose applied to
the water entering the newly laid pipe shall be at least 40 to 50
parts per million. This may require as much as 100 parts per million
of chlorine in the water left in the line after chlorination. A convenient
method of determining the rate of flow of water into the line to be
treated is to start with the line full of water and measure the rate
of discharge at a hydrant with a pilot gauge. Great flexibility is
made possible by providing a series of orifices to give good gauge
readings at high and low flows.
(7)
Preventing reverse flow. Valves shall be manipulated
so that the strong chlorine solution in the line being treated will
not flow back into the line supplying the water.
(8)
Retention period. Treated water shall be retained
in the pipe long enough to destroy all non-spore-forming bacteria.
This period should be at least 24 hours and preferably longer, as
may be directed. After the chlorine-treated water has been retained
for the required time, the chlorine residual at the pipe extremities
and at other representative points should be at least 25 parts per
million.
(9)
Chlorinating valves and hydrants. In the process of
chlorinating newly laid pipe, all valves or other appurtenances shall
be operated while the pipeline is filled with the chlorinating agent.
(10)
Final flushing and test. Following chlorination,
all treated water shall be thoroughly flushed from the newly laid
pipeline at its extremities until the replacement water throughout
its length shall, upon test, be proved comparable to the quality of
water served the public from the existing water supply system. This
quality of water delivered by the new main should continue for a period
of at least two full days as demonstrated by laboratory examination
of samples taken from a tap located and installed in such a way as
to prevent outside contamination.
A.
Materials to be used.
(1)
Pipe and fittings.
(a)
All sewer mains shall be cement-asbestos with
a minimum inside diameter of eight inches.
(b)
No other specifications for concrete or cement-asbestos
sewers are herein contained. The use of other materials is not prohibited
and may be done under standard specifications submitted to and approved
by the Board of Public Works.
(2)
Manholes.
(a)
Manholes shall be constructed at every change
of line or grade of the sewer main, at every main intersection or
branch (except branches for house connections) and in straight runs
of main so that the distance between manholes shall not exceed 300
feet; except that, where the grade of the sewer is more than five
feet in 100 feet, the distance between the manholes shall not exceed
250 feet.
(b)
Manholes may be precast of concrete masonry
of 1-2-4 concrete using tight smooth forms or standard cement manhole
blocks formed especially for four-foot manholes.
(c)
Manholes may be built of brick masonry using
hard-pressed brick. Every fifth course of brick shall be laid as stretchers,
the remainder to be headers. Every brick shall have full mortar joints
on the bottom and sides which shall be formed at one operation by
placing sufficient mortar on the bed and forcing the brick into it.
Horizontal joints shall not exceed 3/8 inch, and vertical joints on
the inside of the manholes shall not exceed 1/4 inch. Joints on the
inside face are to be carefully rubbed full and struck as a manhole
is built. The outside of the manhole shall be smoothly and evenly
plastered with cement mortar 1/2 inch thick. Such plaster coat shall
be applied in one operation after all brick has been placed and must
not be applied by the mason working within the manhole as the brick
courses are laid up. Plaster shall be proportioned one part portland
cement to 2 1/2 parts mortar sand.
[1]
Manhole bottoms.
[a]
Inverts of manholes shall be formed
by running the sewer pipe through the manhole cutting pipe after the
manhole has been completed. Concrete bottoms of manholes shall be
placed in two layers. The top of the bottom layer shall be level with
the horizontal diameter of the pipe, and upon this layer the brick
masonry shall be started. The depth of this concrete shall be everywhere
at least six inches thick. Particular care must be exercised to ensure
this depth under the invert. After the top of the pipe has been cut
off and the invert left in the concrete base, a second concrete floor
must be applied on top of the original bottom to the height of the
top of the sewer pipe leaving the manhole. This floor shall be neatly
shaped to meet the cut half of the sewer pipe and shall serve to confine
the sewage from overflowing on the manhole bottom if the sewer should
flow more than half full.
[b]
Where the invert of the manhole
is below groundwater level, manholes shall be waterproof on the outside
of the plaster coat with suitable bituminous waterproofing to a line
one foot higher than the apparent groundwater level. In wet trenches,
water shall be kept drained away from manholes until the concrete
work is set.
[c]
No backfilling shall be done until
the plaster coat on the outside of the manhole shall have set for
24 hours.
[d]
In freezing weather, customary
precautions of heating materials and after-protection shall be followed.
[2]
Steps. Steps of cast-iron or of galvanized wrought
iron 3/4 inch in diameter shall be securely placed in the inside of
the manhole during construction not more than 18 inches apart.
[3]
Diameter. Manholes five feet deep or less shall
have an inside diameter of four feet at the bottom. Manholes 10 feet
deep shall be five feet in inside diameter, and at intermediate depths
the diameter shall be in proportion.
[4]
Frames and covers. Manhole covers shall be set
to the grade given by the inspector. Covers of manholes in streets
shall correspond to the type used and approved by the City of Ithaca
in 1932, the frame and cover to weigh not less than 480 pounds. The
depth of the frame shall be eight inches, and the diameter of the
cover shall be 24 inches. Manholes in parking areas where no traffic
can be expected may use covers of the lightweight type used in the
City of Ithaca prior to 1932. The weight of the frame and cover shall
be not less than 245 pounds, and the depth of the frame shall be four
inches.
B.
Disposition of defective material. All material found
during the progress of the work to have cracks, flaws, blisters or
other defects shall be rejected by the inspector. All defective material
shall be promptly removed from the site.
C.
Alignment and grade.
(1)
Sewers shall be laid straight to line and grade between
manholes.
(2)
The alignment and grade of the sewer line shall be
checked from a string line stretched along the center of the pipe
between batter boards at every 25 feet. The batter board grades are
taken from the engineer's grade stakes. The elevation of the batter
boards above the invert of the pipe shall be constant for adjacent
batter boards. Batter boards shall be set at every change in line
and grade.
D.
Laying.
(1)
Handling main material into trench. Proper implements,
tools and facilities satisfactory to the inspector shall be provided
and used for the safe and convenient prosecution of the work. All
pipe and fittings shall be carefully lowered into the trench piece
by piece by means of a derrick, ropes or other suitable tools or equipment
in such a manner as to prevent damage to sewer main materials. Under
no circumstances shall sewer main material be dropped or dumped into
the trench.
(2)
Pipelaying. All pipe shall be laid with ends abutting
and true to line and grade, so fitted and matched that a smooth uniform
invert will be formed. The bottom of the trench shall be shaped so
as to conform as nearly as possible to the outside of the pipe, particular
care being taken to recess the bottom of the trench in such a manner
as to relieve the bell of all load.
(3)
Depth. In streets or highways, sewers shall be laid
to a minimum depth of three feet, grade permitting.
(4)
Unsuitable conditions for laying pipe. No pipe shall
be laid in water or when, in the opinion of the inspector, trench
conditions are unsuitable.
E.
Jointing.
(1)
Joints. Pipe joints shall conform to both the materials
and methods of installation of the manufacturer of the particular
cement-asbestos pipe furnished for the job.
(2)
Joints in cold weather. No joints shall be poured
when pipe is at a temperature below freezing. When the air temperature
is below 40° F., the part of the pipe to be joined shall be heated,
and a paint coat of G-K primer, or equal, shall be applied both to
the spigot end and the inside of the bell before pipes are joined
preparatory to pouring.
F.
Testing.
(2)
Testing. On completion of any sewer or such portion
of the same as may be directed and before any connection has been
made therewith, the sewer may be tested for leakage or infiltration
of groundwater on the order of the inspector. Contractors shall supply
all facilities for making such tests. It is the intent of these specifications
to have the sewer so constructed that the quantity of infiltration
will be kept at a minimum. The allowable leakage shall not exceed
a rate of flow of 175 gallons per 24 hours per inch of diameter per
1,000 linear feet of sewer tested. Should any leaky or defective joint
or defective construction be found, it shall be promptly made good;
and should any defective pipes or specials be discovered, they shall
be replaced with sound pipes or specials in a satisfactory manner
and without cost to the city.
