[Adopted 4-29-1981 by L.L. No. 3-1981 as
Ch. 80, Part 2, of the 1975 Code]
Sewers in the Town of LaGrange shall be designed
on the bases established in this article unless otherwise approved
by the Engineer.
The population served shall be determined by
multiplying the number of dwelling units (or predicted number of dwelling
units) by four persons per unit for domestic flows.
A.Â
Average domestic sewer flows shall be determined by
multiplying the population served by the rate of 100 gallons per capita
per day.
B.Â
Average industrial and commercial waste flows shall
be determined by multiplying the area served, in acres, by 10,000
gallons per acre per day. The area shall include that occupied by
streets.
A.Â
For domestic sewage, the ratio of peak to average
flow shall be determined by using Harmon's formula, which may be expressed
as follows:
|
        14
| ||
|
R = 1 +
|
——————
| |
|
   (4 + P 1/2)
| ||
|
Where "R" equals the ratio of peak to average
flow, and "P" equals the population in thousands.
| ||
B.Â
For industrial and commercial areas, the peak waste
flows shall be assumed as equal to two times the average rate.
Minimum mean velocities in sewers shall be two
feet per second when flowing full, based on the Kutter formula with
"n" (coefficient of roughness) equal to 0.013. (Where ground slopes
permit, use three feet per second.) The maximum sewer velocities shall
be 10 feet per second. Velocity head correction shall be made for
velocities of four feet per second or greater. All increments of flow
from building sewers shall be assumed to enter the public sewer at
the upper manhole.
The following are the minimum permissible slopes:
|
Sewer Size
(inches)
|
Minimum Slope
(feet per thousand feet)
|
|---|---|
|
8
|
4.0
|
|
10
|
2.8
|
|
12
|
2.2
|
|
14
|
1.7
|
|
15
|
1.5
|
|
16
|
1.4
|
|
18
|
1.2
|
|
21
|
1.0
|
|
24
|
0.8
|
Generally the depth of sewers shall be not less
than seven feet to invert, except at isolated critical points, as
approved by the Engineer. Depths of collecting sewers shall be coordinated
with any Master Sewer Plan adopted or to be adopted by the Town.
Inverted siphons should not have less than two
barrels with a minimum pipe size of six inches and shall be provided
with the necessary appurtenances for convenient flushing and maintenance.
Manholes shall have adequate clearances for rodding. In general, sufficient
head shall be provided and pipe sizes selected to secure velocities
of at least three feet per second for average flows. The inlet and
outlet details shall be arranged so that normal flow may be diverted
to one barrel to permit either barrel to be cut out of service for
cleaning. Inverted siphons shall be avoided wherever possible.
A.Â
Manholes shall be located at all junctions and changes
in slopes of sewers and at all bends in line for sewers 24 inches
or less in diameter, and shall be spaced at the following intervals:
|
Sewer Size
(inches)
|
Preferred Spacing
(feet)
|
Maximum Spacing
(feet)
| |
|
8
|
300
|
400
| |
|
10 to 15
|
400
|
400
| |
|
Over 18
|
400
|
500
|
B.Â
Drop manholes shall be provided at all junctions where
the drop is more than two feet.
C.Â
At manholes where the pipe size changes, crowns shall
be matched if size is increasing and inverts if size is decreasing,
unless otherwise approved by the Engineer.
A.Â
Interconnections. There shall be no physical connection
between a potable water supply system and a sewer or appurtenances
thereto which would permit the passage of any sewage or polluted water
into the potable water supply. Sewers shall be kept remote from public
water supply wells or other water supply sources and structures.
B.Â
Horizontal separation. Wherever possible, sewers shall
be laid at least 10 feet horizontally from any existing or proposed
water main. Should local conditions prevent lateral separation of
10 feet, the sewer may be laid closer than 10 feet to a water main
if:
C.Â
Vertical separation. Whenever sewers must cross water
mains, the sewer shall be laid at such an elevation that the top of
the sewer is at least 18 inches below the bottom of the water main.
When the elevation of the sewer cannot be varied to meet the above
requirement, the water main shall be relocated to provide the separation
or reconstructed with mechanical joint pipe for a distance of 10 feet
on each side of the sewer. One full length of the water main shall
be centered over the sewer so that both joints will be as far from
the sewer as possible.
D.Â
Pressure testing. When it is impossible to obtain
proper horizontal and vertical separation as stipulated above, both
the water main and sewer should be constructed of mechanical joint
cast-iron pipe and the sewer should be pressure-tested to assure water
tightness.
A.Â
Locations of sewage pumping stations shall be such
that the stations shall not be subject to flooding. The stations shall
be readily accessible.
B.Â
Sewage pumping stations shall be of the dry-well type.
The structures shall:
C.Â
Pumps shall be provided in not less than duplicate
units unless a suitable overflow is permissible for the occasional
discharge of sewage. Where duplicate units are provided, each unit
shall be capable of handling flows in excess of the peak flow. Where
more than two pumps are provided, they shall be designed to match
actual flow conditions and shall be of such capacity as to handle
peak sewage flows with the largest pump out of service. Pumps shall
be capable of passing spheres of at least three inches in diameter.
Pump suction and discharge openings shall be at least four inches
in diameter. The pumps shall be so placed that under normal operating
conditions they will operate under a positive suction head.
D.Â
In enclosed places where gases may accumulate, electrical
equipment shall comply with the National Board of Fire Underwriters
Specifications for hazardous conditions (NEMA Type 7).
E.Â
Dry-well dewatering. A separate sump pump shall be
provided to remove leakage or drainage from the dry well. Discharge
of sump pumps shall be to the wet well at a point above the high-water
level.
F.Â
Ventilation. Adequate ventilation shall be provided.
There shall be no interconnection between the wet-well and dry-well
ventilating systems. Ventilation shall be continuous in wet wells
and shall provide at least 12 complete air changes per hour. Ventilation
for dry wells shall be continuous and provide at least six air changes
per hour.
These specifications shall be used for construction
of sewers within the Town of LaGrange. Such sewers include the public
sewers within the streets and in rights-of-way and the building sewers,
including the necessary structures, such as manholes, pump stations
and appurtenances. These specifications shall be considered to be
the minimum acceptable standards for construction.
As used in this article, the following terms
shall have the meanings indicated:
The numbered specifications of the American Society for Testing
Materials, as revised at the time design is approved.
The Engineer for the Town of LaGrange or his authorized deputy,
agent or representative.
The removal from place of all materials, including soil,
structures above and below ground, rock, topsoil, boggy waste, rubbish,
ashes, cinders or organic materials such as peat or humus.
The legal owner of the real estate to be improved or such
person designated as his agent in writing to the Engineer.
The engineer of record with reference to the sanitary sewer
system.
The owner shall obtain such permits as are necessary
for the opening of streets, sewer design, building permits and such
others as are required by local laws. These permits shall be obtained
prior to the start of construction and at no cost to the Town of LaGrange.
The owner shall be responsible for payment of all fees required by
such local laws.
The Engineer shall be notified at least two
working days in advance of the start of construction.
All materials forming a part of the permanent
construction, as called for on the approved drawings and in the specifications,
shall be first class in every respect and subject to the approval
of the Engineer, who shall be the sole judge of their quality and
suitability for the purposes for which they are to be used. If any
material brought onto the site for use in the work is condemned by
the Engineer, after arrival at the site, as unsuitable or not in conformity
with the specifications, the owner shall immediately remove such material
from the construction site.
Approved drawings shall consist of a set of
plans and profiles prepared by the owner's engineer and submitted
to the Engineer for review and approval as to conformity to the basic
municipal sewer plan and the specifications. The Engineer's approval
shall be affixed to the drawings, and a copy of such approved drawings
shall be on the construction site at all times. No deviation shall
be made from the line and grade shown on the approved drawings except
by written authorization of the Engineer.
The owner's engineer shall provide the Engineer
with a revised set of permanent reproducible drawings showing the
as-built location, sizes and elevations of sewers, manholes, building
sewers, building sewer terminations and easements, together with such
legal descriptions as are required for proper recording of such easements.
A.Â
Clearing and grubbing. Areas to be excavated or filled
areas to be used for the storage of excavated material, and areas
on which pavements or other structures will be constructed, shall
be cleared of all trees, brush, hedges, shrubs, rubbish and other
objectionable matter. Such material shall be disposed of as approved
by the Engineer.
B.Â
Stripping. After cleaning and grubbing, all topsoil
and other organic material shall be stripped within the limits to
be graded, excavated or filled. A minimum of six inches of material
shall be removed from all unpaved areas. All material removed shall
be deposited beyond the limits of the work. The material which is
of acceptable quality for use in the work as topsoil shall be kept
separate from other excavated material and protected and maintained
until needed. All other stripped material shall be considered as surplus
and shall be disposed of as directed by the Engineer.
C.Â
Limit of excavations. Excavations shall be carried
to the dimensions and depths indicated or as necessary to provide
a firm base. Excavations carried below the depth necessary shall be
refilled to the proper grade with thoroughly compacted foundation
material. In no case shall the earth be plowed, scraped or dug by
machinery within three inches of the finished subgrade. The final
trimming of the bottom of excavations shall be done by hand tools
just before placing pipe.
D.Â
Protection of existing structures. Excavations made
adjacent to or in the proximity of existing structures shall be made
with special care and in such manner as not to damage the structures
or to disturb the supporting backfill and foundation of such structures.
E.Â
Sheeting and bracing.
(1)Â
Where excavations are made with vertical sides which
require supporting, the sheeting and bracing shall be of sufficient
strength to sustain the sides of the excavations and to prevent movement
which could in any way injure the work or diminish the working space.
Timber for sheeting and bracing shall be rough, square-sawed of any
grade having the requisite strength for the purpose intended and shall
not split in driving or fabrication. Steel sheet piling shall conform
to the requirements of ASTM A-328. Piping shall be of an interlocking
pattern and shall be of adequate weight and section to withstand the
loads imposed. The owner shall furnish drawings showing sheeting and
bracing methods. For excavations over 12 feet in depth, the owner
shall certify to the Engineer that the sheeting and bracing design
has been checked and approved as adequate and in accordance with existing
laws and regulations by a licensed professional engineer, and that
sheeting and bracing has been constructed in accordance with the design
which was checked and approved by the owner's engineer. Upon request
by the Engineer, the owner shall furnish computations and substantiating
data for review. Certification of design shall be submitted prior
to placing any sheeting and bracing, and certification of construction
shall be submitted immediately after sheeting and bracing has been
constructed.
(2)Â
Where the owner does not propose to sheet and brace
excavations, he shall submit a drawing indicating the side slopes
he proposes to maintain and have those slopes certified by the owner's
engineer as being safe and in accordance with existing laws and regulations.
Upon request by the Engineer, the owner shall furnish design computations
and substantiating data for review. If the owner elects to construct
trenches using soldier beams and horizontal lagging, all such sheeting
and soldier beams more than two feet below the finished surface shall
be left in place.
F.Â
Explosives and blasting. All state, municipal and
other regulations regarding the composition, transportation, storage
and use of explosives shall be strictly complied with. The quantity
of explosives kept on hand shall not exceed the amount that is necessary
to avoid delay in the work. The composition of explosives shall be
such as to cause the least amount of injurious fumes. Blasting shall
be done with light charges sufficient to loosen the rock without damaging
the adjoining or nearby property and without cracking or damaging
rock upon or against which masonry is to be built. Whenever, in the
opinion of the Engineer, blasting is liable to injure rock upon or
against which masonry is to be built, blasting shall be discontinued
and the loosening of the rock continued by wedging and barring or
other approved methods. Rock near structures liable to be damaged
by blasting shall be loosened by approved means.
G.Â
Responsibility of owner in blasting. The owner will
be held responsible for all claims for damage caused by blasting.
He shall satisfactorily cover all shots and open-cut excavations and
shall take extra precautions when required by the Engineer, and shall
at all times exercise caution to prevent accidents.
H.Â
Dewatering. The owner shall provide, operate and maintain
satisfactory facilities and equipment, including well points, if necessary,
with which to collect all water entering excavations or other parts
of the work and convey it to suitable places for disposal. All excavations
shall be kept free of water until the work or structure to be built
therein is completed. Approved settling basins and sumps shall be
provided for catching and temporarily holding water containing mud,
clay, sand or other material in suspension pumped from excavations.
Such basins shall be large enough to allow storage time for the settlement
of such suspended matter. The settled material shall be cleaned out
frequently and disposed of. Lowering of groundwater to the injury
or detriment of other structures shall be part of the owner's risk
and responsibility. Any structure damaged as a result of lowering
of groundwater shall be repaired or replaced to the satisfaction of
the owners thereof.
I.Â
Storage of excavated material. Excavated material
which is suitable and approved for backfill and fill shall be placed
in storage piles unless and/or until it can be placed in the work.
It shall not be placed close to the sides of excavations where the
weight of the material could create a surcharge on such sides, whether
sheeted or not.
J.Â
Borrow material. Where additional material to that
available from the work is required for backfill and fill or other
purposes, it shall be obtained by the owner from outside sources.
Borrow material shall be subject to approval by the Engineer.
K.Â
Backfill and fill.
(1)Â
All backfill and fill, unless otherwise specified,
shall consist of suitable and selected approved earth, generally from
storage or approved excavated soil, free from rejected organic matter
and boggy, peaty, humus or other unsuitable material such as silt,
rubbish, waste, ashes or cinders. If sufficient suitable material
for backfill and fill is not available from the excavated material
as determined by the Engineer, the owner shall procure elsewhere a
sufficient quantity of suitable material and shall furnish and place
such material. Frozen earth shall not be used for backfill and fill.
All rocks and stones more than six inches in the largest dimension
shall be removed from accepted earth for backfill and fill.
(2)Â
Backfill and fill shall be made to the slopes, grades
and elevations required.
(a)Â
Backfill shall not be placed until the structure
has been inspected in place and approved by the Engineer. Backfilling
shall be carried out as soon as possible after such approval. The
extent of pipe trench kept open shall be kept to a minimum. Backfill
and fill shall be placed in layers not more than 12 inches thick except
as specified otherwise by the Engineer. Each layer shall be compacted
thoroughly, evenly and in such manner as to provide practically unyielding
surfaces. The moisture content of the materials shall be such that
proper compaction shall be obtained.
(b)Â
Trenches shall be backfilled to a depth not
less than 12 inches above the top of the pipe or other structure therein
and for the full width of the trench. Such backfill shall be uniformly
placed on each side of the pipe in six-inch layers where it is required
and firmly compacted by approved mechanical tamping equipment. Care
shall be taken not to damage the pipe or structures.
(c)Â
After a compacted coverage of 12 inches has
been made, the remainder of the trench shall be compactly filled in
an approved manner to a density at least equal to that of the adjacent
undisturbed soil so as to avoid future unequal settlement. Puddling
for compaction will not be permitted except with coarse to medium
granular materials. Bulldozing of backfill material into trenches
will be prohibited unless it is done in uniformly spread layers not
over 12 inches thick, or six inches thick under pavements, and each
layer immediately machine-tamped. Where sheeting is withdrawn, all
cavities left thereby shall be filled with suitable granular earth,
hosed or tamped in place so as to fill all voids thoroughly. Backfill
and fill shall be carried to a subgrade which permits topsoil or paving
of the required depth to be placed to bring it to the finished grade.
As far as practicable, the underlying backfill and fill shall be given
time to settle through several heavy rains or by artificial wetting
before the topsoil or paving is placed.
L.Â
Foundation material. Foundation material shall consist
of hard and clean gravel or crushed stone. It shall be free from any
considerable amount of flat, laminated or elongated particles and
shall be free from shells, clay, limestone, shale or other deleterious
matter. Gravel or crushed stone shall be graded from 1/4 inch to No.
4 sieve size. Foundation material shall be placed and firmly compacted
by mechanical compacting equipment. Care shall be taken to place and
compact material under pipe haunches.
A.Â
Materials.
(1)Â
Segmental concrete blocks shall conform to the requirements
of ASTM C139.
(2)Â
Precast concrete pipe manhole risers shall conform
to the requirements of ASTM C478, except that joints shall conform
to the requirements of ASTM C443, with rubber rings conforming to
ASTM D1869.
(3)Â
Mortar shall consist of two parts portland cement
and five parts sand thoroughly mixed in the required proportions before
adding water.
(4)Â
Grout shall consist of Type 1 and Type 2 portland
cement and fine sand and shall contain a compound that will eliminate
shrinkage of the grout. The nonshrink grout compound shall be equal
to Sika Kemox-C and shall be used in strict accordance with the manufacturer's
recommendations.
B.Â
Construction. Manholes shall be constructed of precast
concrete manhole risers in accordance with the details furnished by
the Engineer. The waterways of all manholes shall be formed of the
same size and shapes as the pipes they connect to. Changes in diameter
shall be made gradually and evenly. Special care shall be taken to
form channels that will provide the best hydraulic conditions for
smooth flow. Steel trowel finish shall be provided. Slopes shall be
provided on the benches adjacent to the waterways as shown. Masonry
for adjustment of height of manhole chimneys shall be laid in a full
bed of mortar, with mortar spread on the sides and ends of each unit
filled solidly as the work is carried out. The inside of the block
shall be rubbed with a burlap sack to clean it of spilt mortar. The
exterior surface of brick or block shall be plastered with a one-half-inch
layer of mortar. Particular care shall be taken to secure watertight
joints between the masonry and the precast concrete on which it rests.
C.Â
Appurtenances. Manholes, frames and covers shall be
of the best quality, close-grained, gray iron castings conforming
to the requirements of ASTM A48 Class 30. Standard manhole frames
and covers shall be equal to Campbell Foundry Company Pattern No.
1203. Frames and covers for shallow manholes shall be equal to Campbell
Foundry Company Pattern No. 4430. Covers shall bear the words "LaGrange"
and "Sewer" in two-inch flat Gothic letters. Covers on manholes on
the discharge end of force mains and on manholes adjacent to any pumping
station shall be provided with four three-fourths-inch vent holes
equally spaced. The castings shall be free from faults, sponginess,
cracks, blowholes and other defects affecting their strength and shall
be properly cleaned and coated with a waterproof asphalt applied by
immersion while castings are hot. Frames and covers shall be machined
to ensure a nonchattering fit. Manhole frames shall be set to grade
on a full bed of grout.
A.Â
Pipe and fitting materials. Materials for pipes and
fittings shall be in accordance with the following schedule:
|
Pipe Material
|
Standard
|
Class
| |
|---|---|---|---|
|
Concrete
|
ASTM C-14
|
Extra strength
| |
|
Reinforced concrete
|
ASTM C-76
|
As specifieda
| |
|
Vitra chem
|
CSPA 2
|
Extra strength
| |
|
Asbestos cement
|
ASTM C-428
|
As specified
| |
|
ASTM C296
| |||
|
Cast iron
|
ASA A21.6
| ||
|
ASA A21.8 and ASA A21.10
|
As specifiedb,c
| ||
|
NOTES:
| |||
|
aOnly circular reinforcement
will be permitted. Specially designed pipe noted as Class VI shall
have the following minimum three-edge-bearing test loads:
| |||
|
    D-load to produce a
0.01-inch crack 3,000
| |||
|
    D-load to produce ultimate
failure 4,500
| |||
|
bFittings larger
than 12 inches in size shall be equal to those shown in Section 10
of the Cast Iron Pipe Research Association's Handbook of Cast Iron
Pipe.
| |||
|
cAll pipe and fittings
shall have a cement mortar lining conforming to the requirements of
ASA Standard A21.4.
| |||
B.Â
Pipe joints. All pipe joints shall be of a flexible
type and shall be in accordance with the following schedule:
|
Pipe Material
|
Standard
| |
|---|---|---|
|
Concrete
|
ASTM C443a
| |
|
Reinforced concrete
|
ASTM C443a
| |
|
Vitra chem
|
ASTM C425b
| |
|
Asbestos cement
|
Fed. Spec. SS P-331ba,c
| |
|
Cast iron
|
ASA A21.11d,e
| |
|
NOTES:
| ||
|
aPipe joints shall
be designed to meet the sheer loading requirements of ASTM C425.
| ||
|
bSection 7 of ASTM
C425 is modified by the requirements specified hereinafter.
| ||
|
cRubber rings shall
conform to ASTM D1869 and shall be of the oil-resistant type.
| ||
|
dUnited States Pipe
and Foundry Co. Tyton joint may also be used.
| ||
|
eWhere tied joints
are required, they shall be designed to resist the tensile loads,
including water hammer. Anchorages and pipe shall be proportioned
accordingly.
| ||
C.Â
Shop tests. The owner shall conduct tests for strength,
infiltration and exfiltration of selected lengths of pipe prior to
and while furnishing the pipe. The owner shall notify the Engineer
a minimum of five days prior to the date of testing so that the test
may be witnessed. The strength test shall be in accordance with the
following schedule:
|
Pipe Material
|
Test Standard
|
Method
|
Percentage Tested*
|
|---|---|---|---|
|
Concrete
|
ASTM C14
|
3-edge
|
0.5%
|
|
Reinforced concrete
|
ASTM C76
|
3-edge
|
1.0%
|
|
Vitra chem
|
ASTM C301
|
3-edge
|
0.5%
|
|
Asbestos cement
|
ASTM C269 or 428
|
Crushing
|
1.5%
|
|
Cast iron
|
ASA A21.6 or 21.8
|
Ring
|
1.5%
|
|
NOTES:
| |||
|
*Percentage applies to the number of pipes of
each size and class to be furnished. There shall be not fewer than
two tests for each size and class.
| |||
D.Â
Pipe laying. All pipe and fittings shall be installed
to the lines and elevations shown on the drawings approved by the
Engineer and in accordance with the manufacturer's requirements. In
general, all pipe shall be laid in accordance with the agreed requirements
of ASTM C12, utilizing foundation material as specified under § 187-64M
and the applicable portions of Section 5 of the Handbook of Cast Iron
Pipe. Alignment shall be maintained by stretching a guide line parallel
to and at a determined distance above the pipe invert. The line shall
be tight and shall be supported at the required elevation every 25
feet. The invert of each successive pipe shalt be checked for alignment
and elevation with the guide line. Suitable tools and equipment shall
be used for proper handling, storage and laying of pipe and fittings.
In order to avoid damage to interior coatings of pipe, lifting hooks
or bars shall not be inserted therein. Each pipe and fitting shall
be checked for defective injuries as laying proceeds. Imperfect pipe
material shall be rejected and removed from the work. Pipe found to
be defective after laying shall be removed and replaced by undamaged
pipe. Pipe shall be cut as required to meet required stations. Where
pipe must be cut to fit as closing pieces, such cuts shall be evenly
and squarely made in a workmanlike manner with approved equipment.
Injury to linings and coatings shall be satisfactorily repaired. All
pipe joints shall be made in accordance with the manufacturer's recommendations.
Unless otherwise permitted, all finished joints of all kinds of pipe
shall be left exposed for inspection and acceptance by the Engineer.
E.Â
Pipe flotation. Inasmuch as the submerging of the
empty pipeline could cause flotation, the owner's attention is directed
to the necessity of conducting his operations in such a manner as
to prevent flooding of the trenches until the backfill has been placed.
Wherever there is a danger to flooding prior to placing backfill,
the pipe shall be filled with water or adequately braced to the sheeting
to prevent flotation. The owner shall be responsible for relaying
any pipe damaged or moved from proper line and grade.
F.Â
Sewer to be kept clean. The interior of the sewer
shall be clear of dirt, cement, superfluous materials of every description
and kept clean as the next section of the pipe is laid. During the
progress of the work, the exposed ends of the pipe shall be provided
with temporary covers fitted to the pipe so as to exclude earth and
other materials. On completion of the sewer, the lower end shall be
securely closed by an approved bulkhead or plug, which shall be removed
only on order of the Engineer.
G.Â
Field tests. The owner shall furnish all labor, testing
equipment and materials and shall perform the tests described herein
under the supervision and to the satisfaction of the Engineer:
(1)Â
Alignment and openness of joints shall be checked
with reflected sunlight and flashlights, and if necessary, wooden
balls and water. The pipe shall be true to both line and grade, shall
be free of cracks and protruding joint materials and shall be clean.
(2)Â
Exfiltration and infiltration tests shall be conducted
on completed sections of the sewers not to exceed 1,000 feet in length,
and each test duration shall be not less than eight hours. Shorter
test sections may be required for sewers laid on steep grades. All
required pumping shall be carried out.
(3)Â
Sewer pipes shall first be tested for exfiltration.
Plugs shall be provided in manholes to isolate the test section. The
pipe and manholes shall be filled with water to provide at the high
points of the test section a minimum head of five feet above groundwater
or the top of the pipe, whichever is higher. Approved standpipes or
test pits shall be provided to check the groundwater levels. This
level must be maintained for the duration of the test. Volumetric
measurement of the water added shall be made. Exfiltration shall be
limited to a maximum of 15 gallons per hour per inch of internal diameter
per mile of sewer pipe.
(4)Â
Upon completion of the exfiltration tests, sewer pipes
shall be tested for infiltration. Groundwater levels must be permitted
to return to their normal levels prior to test. Infiltration shall
be checked using weirs, gauges and other measuring devices approved
by the Engineer. Temporary bulkheads shall be provided to shut off
all flow from above the section to be tested and pumps shall be provided
downstream from the weir to keep it continuously drained for the duration
of the test. Infiltration shall be limited to a maximum of 15 gallons
per hour per inch of internal diameter per mile of sewer pipe. In
addition, the owner and Engineer shall together inspect the interior
of all pipe in wet weather, and all obvious leaks shall be repaired
even though the total infiltration meets the requirements.
(5)Â
For the purpose of determining the maximum permissible
infiltration and exfiltration, an allowance of 1/2 gallon per manhole
per hour shall be assumed. However, no allowance shall be made for
the various lengths of building sewers. If infiltration or exfiltration
exceeds the specified amounts, the owner shall do whatever is necessary
to reduce the infiltration and exfiltration to within the specified
limit, as approved.
(6)Â
Force mains shall be bulkheaded as required and tested
for leakage at a constant test pressure of 10 pounds per square inch
higher than the anticipated working pressure of the pipe under operation.
The duration of the test shall not be less than four hours, and leakage
shall not exceed 2 1/2 gallons per hour per inch of internal diameter
per mile of pipe.
H.Â
Choice of pipe.
(1)Â
The choice of pipe shall be optional with the owner
as follows:
|
Sewer Diameter
(inches)
|
Depth to Invert
(feet)
|
Type and Class of Pipe
|
|---|---|---|
|
8
|
3-18
|
Asbestos cement, 2400; or vitra chem
|
|
10
|
4-15
|
Asbestos cement, 2400; or vitra chem
|
|
15-20
|
Asbestos cement, 3300
| |
|
12
|
4-11
|
Asbestos cement, 2400; or reinforced concrete,
III
|
|
11-12
|
Asbestos cement, 2400; or reinforced concrete,
IV
| |
|
12-14
|
Asbestos cement, 3300; or reinforced concrete,
IV
| |
|
14-18
|
Asbestos cement, 4000; or reinforced concrete,
V
| |
|
18-20
|
Asbestos cement, 5000; or reinforced concrete,
VI
| |
|
15
|
4-8
|
Reinforced concrete, III; or 15" or 16" asbestos
cement, 2400
|
|
8-13
|
Reinforced concrete, IV; or 15" or 16" asbestos
cement, 3300
| |
|
13-17
|
Reinforced concrete, V; or 15" or 16" asbestos
cement, 5000
| |
|
17-20
|
Reinforced concrete, VI; or 15" or 16" asbestos
cement pressure, 150
| |
|
18
|
4-9
|
Asbestos cement, 3300; or reinforced concrete,
III
|
|
9-12
|
Asbestos cement, 4000; or reinforced concrete,
IV
| |
|
12-14
|
Asbestos cement, 5000; or reinforced concrete,
V
| |
|
14-17
|
Asbestos cement pressure, 150; or reinforced
concrete, V
| |
|
21
|
5-14
|
Reinforced concrete, IV; or 21" or 24" asbestos
cement pressure, 100
|
|
14-18
|
Reinforced concrete, V; or 21" or 24" asbestos
cement pressure, 150
| |
|
18-22
|
Reinforced concrete, VI; or 21" or 24" asbestos
cement pressure, 150
| |
|
24
|
6-14
|
Asbestos cement pressure, 100; or reinforced
concrete, IV
|
|
14-19
|
Asbestos cement pressure, 150; or reinforced
concrete, V
| |
|
19-22
|
Asbestos cement pressure, 150; or reinforced
concrete, VI
| |
|
4-, 6- and 8-inch force mains
|
3-10
|
Asbestos cement pressure, 100; cast iron, 22
|
(2)Â
Unless otherwise noted, no change in the class or
material of sewer pipe shall be made between adjacent manholes, and
the greatest depth of trench between the two adjacent manholes shall
govern the class of pipe used for that particular section of sewer.
(3)Â
The drawings submitted to the Engineer by the owner
shall contain a detailed list of the type of pipe to be used for the
various sections of the work, with the limits designated by street
and station.
A.Â
Location; residential building sewers.
(1)Â
A building sewer shall be extended from the public
sewer to within five feet of the inside face of the building foundation
in a location which permits ready connection to the building drain.
The building sewer shall be reviewed by the Engineer as to suitability
of location, depth and slope. The actual location of the end of the
building sewer shall be indicated on the working drawings filed with
the Engineer.
(2)Â
Residential building sewers shall be uniformly six
inches in diameter from public sewer to building drain and be constructed
of vitra chem pipe, Class 2400 asbestos cement pipe or cast iron soil
pipe. Adapters shall be used where required.
B.Â
Building sewers for commercial installations. Building
sewers for commercial installations shall be not less than six inches
in diameter from public sewer to building line and be constructed
of the materials specified hereinbefore. The size of the building
sewer for commercial installations is subject to review by the Engineer,
depending upon the intended usage and flow requirements.
C.Â
Bends. All major bends in building sewers shall be
by standard fittings. Minor deflections may be made in building sewers
without the use of fittings. Fittings shall demonstrate the same strength
characteristics as the building sewer.
D.Â
Requirements.
(1)Â
Building sewers shall be laid at a uniform grade of
not less than 1/8 inch per foot. The provisions for excavation and
trenching included in these specifications shall apply to building
sewer construction.
(2)Â
Risers shall be used where public sewer is deeper
than 14 feet below the grade.
(3)Â
Watertight caps or plugs shall be provided for building
sewers not connected to the building drains.
Upon completion of backfilling and compacting
sewer trenches, the public roads shall be repaired. Base course of
a minimum thickness of three inches shall be installed and maintained
by the owner, at no cost to the Town, until approval is granted by
the Engineer to complete paving in accordance with the requirements
of the Town. On private thoroughfares, all effort shall be directed
to compacting the trench areas prior to final grading of the subbase.
The subbase shall meet the requirements of the Town. The owner shall
provide such lights, barriers and guards as required by the Engineer
for marking construction on public roads.
The Engineer reserves the right to issue supplemental
specifications describing the workmanship and the material requirements
for approved construction not defined by these specifications.
Design and criteria for pump stations shall
be submitted to the Engineer prior to placement of purchase orders
or the start of detail design.
