As used in this article, the following terms shall have the
meanings indicated:
BRANCH SEWER
A sewer which receives sewage from a relatively small area,
through two or more laterals, and discharges to a main sewer.
BUILDING DRAIN
That part of the lowest piping of the wastewater drainage
system of a building which receives the sanitary sewage from soil
pipes, waste pipes, and other drainage pipes inside the perimeter
walls of the building and conveys it to the building sewer, which
begins approximately five feet outside the building wall.
BUILDING LEAD
That portion of the building sewer extending from the public
sewer main to the right-of-way line or easement.
BUILDING SEWER
The extension from the building drain, at a point adjacent
to the building foundation, to the building lead.
LATERAL SEWER
A sewer which discharges into a branch or other sewer and
has only building sewers tributary to it.
PUBLIC SEWERS
All sanitary sewers which are designed to provide service
to more than one parcel of land or more than one building shall be
dedicated to Northville Township and shall be a public sewer.
All construction plans shall be submitted to the Township for
sanitary sewer approval and shall contain, but not be limited to,
the following information:
A. Certification. The plans and specification shall be prepared under
the supervision of a civil engineer registered in the State of Michigan.
The title sheet of the plans shall contain the signature and seal
of that engineer.
B. Plan contents. Plans shall consist of a title sheet showing a plan
view of the complete job, split plan and profile sheets, and standard
detail sheets. Sheet sizes shall be 24 inches by 36 inches.
(1) Title sheet. A title sheet, or the first sheet of a set of plans,
shall identify:
(b)
Location map with North arrow and scale, drawn at a scale not
greater than one inch equals 100 feet nor smaller than one inch equals
2,000 feet. Locations of proposed sewers and relationship of general
project area to the surrounding area shall be shown.
(c)
Overall layout of the sewer system with manhole numbers.
(g)
Name, address, phone number and e-mail of proprietor.
(h)
Name, address, phone number and e-mail of designer.
(i)
Plan completion date and all revision dates.
(j)
A statement that the work shall conform to the Township's
current standards and specifications.
(k)
Provide calculations to identify the average day and peak hour
sewage flow.
(2) Plan and profile sheets.
(a)
Scale of plan portion of sheet shall be one inch equals 50 feet,
or larger, with scale of profile portion of sheet one foot equals
five feet vertical or proportionally larger.
(b)
Plan portion of sheet shall include, at least:
[1]
Two bench marks shall be shown on each plan sheet. Plans shall
be prepared based on the Michigan South State Plane Coordinates, North
American Datum of 1983 (NAD 1983) for the x and y coordinate system,
and based on the North American Vertical Datum of 1988 (NAVD88) for
the z coordinate system.
[2]
Existing topography extending 50 feet past the site boundaries,
including all existing and proposed improvements. Elevation contours
shall be at a minimum of two-foot intervals.
[3]
Street names, street and easement width, subdivision names,
lot numbers and lot dimensions.
[4]
Location, length, size of each section of proposed sewer between
manholes.
[5]
Locations of all manholes and other sewer appurtenances and
special structures.
[6]
All proposed building leads and wyes. Length, size, end of lead
invert elevations, and length of riser shall be shown.
[7]
Dimensions to manholes and sewers from property lines, right-of-way
lines or buildings.
[9]
Limits of special backfill requirements.
(c)
Profile portion of sheet shall appear below the corresponding
plan portion, generally projected vertically, and shall show, at least,
the following:
[1]
Size, slope, length, type and class of pipe.
[2]
Invert of each pipe and top-of-casting elevations at each manhole.
[3]
Limits of special backfill requirements.
[4]
Profiled elevations over center line of proposed sewer of existing
and proposed ground, and pavement surfaces. The existing profile shall
be obtained from actual field survey data.
[5]
All crossings with other utilities (existing or proposed) with
elevations of the top or bottom of the pipe, as appropriate, and shall
have "Warning" notes for all gas main crossings in profile.
[6]
Location, by station, or coordinate, of every proposed manhole
with manhole number, top-of-casting elevation, and manhole type.
[7]
Location by station, or coordinate, of all building sewers,
and wye branches.
(3) Detail sheets. Provide Township standard detail sheets consisting
of specifications and drawings. Wayne County details shall also be
provided, where applicable.
All sanitary sewers proposed within the Township shall be constructed
in accordance with the standards and specifications contained herein
or, when by reference, the code.
A. Wyes, riser and building leads.
(1) All wye branches in the sewer pipe shall have manufactured joints.
All pipes containing wye branches shall be installed with the main
sewer. Wyes for vacant property shall be installed opposite the center
of the frontage unless otherwise indicated. The final location of
the wye shall be determined by the Director or his designee at the
time of construction. All wyes that are installed with building leads
shall end with an approved stopper.
(2) The ends of leads shall terminate with an approved stopper set five
feet inside the property line or five feet outside the easement line.
The ends shall be marked with a hardwood stake two inches by two inches
placed vertically from the pipe invert to the ground service.
B. Connections.
(1) A channel shall be constructed within the existing manhole or other
structure, at which the connection is to be made to direct the flow
to the existing outlet. Any portion of the existing structure which
would interfere with such construction shall be removed.
(2) When connections are made with sewers in service, no part of the
work shall be built under water. A flume or dam must be installed
and pumping maintained until completed. All the new work shall be
kept dry until completed. All the new work shall be kept dry until
completed and until all concrete or mortar has sufficiently cured.
(3) The contractor shall install a watertight bulkhead to prevent water,
sand, silt, etc., from entering the existing sewer system. The bulkhead
shall be left in place until the sewer has been tested and approved
by the Director and other entities having jurisdiction.
(4) Wherever existing manhole structures are to be tapped, holes shall
be drilled at four inches center to center around the periphery of
any proposed pipe opening to create a plane of weakness before breaking
out the section. The pipe (stub or saddle) to be placed between the
pipe and the inside wall of the manhole filled cement mortar and trawled
smooth. Voids outside the pipe barrel shall be sealed with an approved
nonshrinking grout. A concrete collar shall then be poured 12 inches
thick around the pipe, and extended a minimum 12 inches beyond the
outside wall of the manhole. The concrete collar shall bear on undisturbed
earth of fully compacted backfill.
(5) Whenever a pipe is to be tapped, a saddle-type wye connection shall
be used. The opening in the existing pipe wall shall be cut with a
masonry circular saw. A concrete collar four inches thick shall then
be poured around the existing pipe extending 12 inches on either side
of the connection.
C. Manholes. Construction methods shall conform to the requirements
of these specifications and Section 5.14.03 of MDOT 1984 Standard
Specifications for Construction with the following stipulations and
exceptions:
(1) Pipe shall not extend into a manhole beyond the inside face of the
manhole wall.
(2) Concrete placed inside precast flexible joint manholes to form the
channel through the manhole shall not be placed between the pipe and
the opening in the manhole base section so as to interfere in any
way with the flexibility of the joint.
(3) A minimum of three inches and a maximum of 15 inches of adjustment
rings with gaskets shall be placed on the cone section of all manholes.
(4) Manhole assembly shall be in accordance with the manufacturer's
recommendation. The bell and spigot surfaces shall be wiped clean.
The surfaces shall be wiped clean. The surfaces (bell, spigot, synthetic
rubber O-ring gasket) shall then be coated with a lubricating material.
(5) All lift holes and joints within precast manholes shall be plugged
and mortared.
(6) All manholes shall be supported on a firm stable foundation.
(7) Channels shall be constructed by a single concrete pour. Concrete
shall be MDOT 30M or 30P. No brick or block will be allowed as filler.
D. Casting adjustments.
(1) Adjustments to manhole castings shall be accomplished prior to final
acceptance by using precast concrete adjustment rings bolted to the
connection of the manhole with synthetic rubber O-ring gaskets compressed
between each adjacent ring.
(2) Manhole castings located within pavement areas shall be adjusted
a maximum of 15 inches using four cadmium-coated five-eighths-inch-diameter
threaded studs with adjustment support nuts for setting frame to correct
grade as detailed on the plan. The void between casting and top of
cone section shall be completely filled with stiff MDOT 30m or 30P
concrete mix having less than three inches slump. A Cadilloc brand
rubber wrap for watertightness shall be applied to the exterior of
the adjustment after the concrete has taken its initial set, and is
resistant to damage, unless otherwise specified by the Director.
E. Acceptance tests. All tests shall be conducted under the supervision
of the Director. No acceptance tests, excluding compaction testing,
shall be conducted until the entire sewer system is constructed and
has been installed for not less than 30 days. All PVC lines shall
be tested for deflection. Sewer pipe 24 inches and smaller shall be
air tested. Sewer pipe larger than 24 inches shall be tested by either
infiltration or exfiltration and shall be tested in lengths of 1,600
feet or less. A copy of all test results shall be furnished to the
Director.
(1) Compaction test.
(a)
Where sanitary sewer is constructed in pavement areas, or where
the sewer is within a one-on-one influence of pavement, compaction
testing shall be performed by an independent testing laboratory.
(b)
Testing shall be performed at intervals of one test per layer
per 75 feet of trench or as determined necessary by the Director.
(2) Test for leakage; air test.
(a)
After a manhole-to-manhole section of line has been backfilled
and cleaned, it shall be plugged at each manhole with pneumatic plugs.
The design of the pneumatic plugs shall be such that they will hold
against the line test pressure without requiring external blocking
or bracing.
(b)
There shall be three hose connections to the pneumatic plug.
The second hose shall be used for continuously reading the air pressure
rise in the sealed line. The third hose shall be used only for introducing
low-pressure air into the sealed line.
(c)
There shall be a 0-30 psig gauge for reading the internal pressure
of the line being tested. Calibrations from the 1-10 psig range shall
be in tenths of pounds (not ounces), and this 0-10 portion shall cover
90% of the complete dial range.
(d)
Low-pressure air shall be introduced into the sealed line until
the internal air pressure reaches 4.0 psig greater than the average
back pressure of any groundwater pressure that may be over the pipe.
At least the stabilization period the third hose shall be disconnected.
(e)
The portion of line being tested shall be accepted if the portion
under test meets the following conditions:
[1]
DI and RCP pipes.
[a]
The time requirement for the pressure to decrease from 3.5 psig
to 2.5 psig (greater than the average back pressure of any groundwater
that may be over the pipe) shall not be less than the time given in
the following table:
|
Pipe Size
(inches)
|
Minutes Holding Time
(seconds/100 feet of pipe)
|
---|
|
4
|
18
|
|
6
|
42
|
|
8
|
72
|
|
10
|
90
|
|
12
|
108
|
|
15
|
126
|
|
18
|
144
|
|
21
|
180
|
|
24
|
216
|
[b]
Immediately prior to the performance of the line acceptance
test, the groundwater level shall be determined by removing the pipe
cap, blowing air through the pipe nipple into the ground so as to
clear it, and then connecting a clear plastic tube to the pipe nipple.
The hose shall be held vertically and a measurement of the height
in feet of water shall be taken after the water stops rising in this
plastic tube. The height in feet shall be divided by 2.3 to establish
the pounds of pressure that will be added to all readings. For example,
if the height of water is 11 1/2 feet, then the added pressure
will be five psig. This makes the 3.5 psig to be 8.5 psig and the
2.5 psig to be 7.5 psig. The one-pound allowable drop and the timing
remains the same.
[2]
PVC pipe.
[a]
The time requirement for the pressure to decrease from 3.5 psig
to 3.0 psig (greater than the average back pressure of any groundwater
that may be over the pipe) shall be calculated as shown in the following
table, where "L" equals the length of sewer to be tested in feet;
however, in no instance shall the holding time be less than the minimum
values shown in the following table:
|
Pipe Size
(inches)
|
Holding Time
(seconds)
|
Minimum Holding
(seconds)
|
---|
|
4
|
0.190XL
|
113
|
|
6
|
0.427XL
|
170
|
|
8
|
0.760XL
|
227
|
|
10
|
1.187XL
|
283
|
|
12
|
1.709XL
|
340
|
|
15
|
2.671XL
|
425
|
|
18
|
3.846XL
|
512
|
[b]
If any section of the sewer fails to meet this requirement,
the contractor shall perform a television inspection of the faulty
section and repair or replace all defective materials and/or workmanship
to the satisfaction of Director. The test procedure shall be repeated
until the results are acceptable.
(3) Television inspection.
(a)
All sanitary sewers shall be television inspected with test
results approved by the Director prior to placing the sewer into service.
(b)
All courses not true to line or grade shall be dug up, relayed
and re-televised. Television inspection for all sanitary sewers eight
inches in diameter and above shall be provided by the contractor.
(4) Deflection testing for PVC pipe.
(a)
All completed installation shall at no point have out-of-round
pipe deflections greater than 5%. The Director shall have the option
of requiring deflectometer or go-no gauging tests run prior to acceptance
on pipe lines where high deflections are suspected. Pipe with deflections
greater than 5% will be considered unacceptable and shall be relayed
by the contractor.
(b)
Deflection of PVC pipe shall be tested by pulling a wooden pig
or equivalent through the pipe. The pig shall be constructed in accordance
with the following table of maximum outside diameters and shall be
submitted to the Director for review before testing in initiated.
|
Pipe I.D.
(inches)
|
Pig O.D.
(inches)
|
---|
|
6
|
5.45
|
|
8
|
7.28
|
|
10
|
9.08
|
|
12
|
10.78
|
|
15
|
13.20
|
|
18
|
16.12
|
(c)
The pig shall be drawn through the pipe from manhole to manhole.
Any portion of pipe through which the pig passes freely shall be deemed
to have passed the deflection test. Sections of pipe through which
the pig does not pass shall be located, uncovered and the pipe zone
bedding improved and backfilled by the contractor. The pipe shall
be retested before acceptance is granted.
(d)
In the event the line does not pass the infiltration test as
stated above, the test shall be repeated after suitable repairs have
been completed.
F. Documents required prior to final acceptance. Prior to the acceptance
of a sanitary sewer by the Township, the following documents shall
be submitted:
(1) Bill of sale conveying the sanitary sewer and all appurtenances to
the Township.
(2) Construction record drawings in accordance with Article
XII of these standards.
(3) Maintenance bond in the amount of 25% of the cost of construction
extending for a term of one year after conveyance to and acceptance
of the sanitary sewer by the Township.
(4) A final waiver of lien from the contractor(s) and subcontractor(s)
who constructed the sanitary sewer, and the suppliers of materials
used in the construction of the sanitary sewers, and a sworn statement
from the proprietor of the development that all financial obligations
of every nature in connection with the sanitary sewer and its appurtenances
have been paid and that there are no outstanding bills, liens, judgments,
etc., against the sewer system.
(5) Sanitary sewer easements (if required). Easements shall be submitted
on the current Northville Township easement form with exhibits prepared
on 8 1/2 inches by 14 inches sheets. The exhibits shall include
a drawing of the location of the sewer relative to the property boundary
and a written legal description.