Note: Descriptions are shown in the official language in which they were submitted.
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P518654CIP-CA
MANHOLE LID TO BASE CONNECTION
RELATED APPLICATIONS
[0001] This application claims priority benefit of US Patent
Application
Serial number 16/370,794 filed on March 29, 2019.
BACKGROUND OF THE DISCLOSURE
Field of the Disclosure
[0002] This disclosure relates to the field of manholes assemblies for
access
to an underground sewer system with corrosion resistant components. The
components vertically connected in one example for ease in installation and/or
transport.
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BRIEF SUMMARY OF THE DISCLOSURE
[0003] Disclosed herein is a manhole assembly. The manhole assembly in
one example comprising: a manhole base, riser, manhole cap, and cover
assembly. The manhole base in one example comprising an aggregate main
body having an upper surface forming a bench, a bottom surface, and a radially
outward surface with penetrations there through; channels formed in the upper
surface of the manhole base fluidly connecting the penetrations; and a radial
spigot in the radially outward upper edge of the manhole base. The manhole
base having a continuous corrosive-resistant layer covering the channels,
bench,
and radial spigot. Also disclosed in one example is a manhole riser comprised
of
a corrosive-resistant structural pipe having a radially outward surface, an
inner
surface and a bottom surface in contact with, supported by, and sealed to the
radial spigot. The manhole cap in one example comprising an aggregate main
body having an upper surface, a bottom surface, and a radially outward
surface;
a radial spigot in the radially outward bottom edge of the manhole cap; the
manhole cap having a continuous corrosive-resistant covering the bottom
surface, radial spigot, and access hole; the radial spigot in the radially
outward
bottom edge of the manhole cap resting upon and sealed to an upper edge of the
manhole riser; wherein the radially outward surface of the manhole cap is
aligned
with the radially outward surface of the manhole riser, and the radially
outward
surface of the manhole base is aligned with the radially outward surface of
the
manhole riser.
[0004] The manhole assembly may be arranged wherein the manhole riser
comprises polyvinyl chloride.
[0005] The manhole assembly may be arranged wherein the riser consists
of
polyvinyl chloride.
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[0006] The manhole assembly may be arranged wherein the aggregate
material is concrete.
[0007] The manhole assembly may be arranged wherein the manhole base
has an outer diameter equivalent and substantially aligned with the outer
diameter of the riser.
[0008] The manhole assembly may further comprise a wrap seal sealed to
the radially outer surface of the riser and the manhole base.
[0009] The manhole assembly may be arranged wherein the manhole cap
has an outer diameter equivalent and substantially aligned with the outer
diameter of the riser.
[0010] The manhole assembly may further comprise a wrap seal sealed to
the radially outer surface of the riser and the manhole cap.
[0011] The manhole assembly may be arranged wherein the riser is a
length
of straight pipe.
[0012] The manhole assembly may be arranged wherein the pipe is a
monolithic structure of corrosion resistant material.
[0013] The manhole assembly may be arranged wherein a tensile lifting
strut
extends from the manhole cap, past the riser, to the manhole base to maintain
the riser adjacent the manhole cap and the manhole base adjacent the riser.
[0014] The manhole assembly may be arranged with the lifting connector
transferring lifting force in tension from the manhole cap to the manhole base
to
the riser.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE
DRAWINGS
[0015] Fig. 1 is a front cutaway view taken along line 1-1 of Fig. 5.
[0016] Fig. 2 is a side cutaway view taken along line 2-2 of Fig. 5.
[0017] Fig. 3A is an enlarged detail view of the region 3 of Fig. 1 of
an
example not attached to a riser.
[0018] Fig. 3B is an enlarged detail view of the region 3 of Fig. I.
[0019] Fig. 4A is an enlarged detail view of the region 4 of Fig. 2 of
an
example not attached to a riser.
[0020] Fig. 4B is an enlarged detail view of the region 4 of Fig. 2.
[0021] Fig. 5 is a plan view taken along line 5-5 of Fig. 1.
[0022] Fig. 6 is a detail view of the region 6 of Fig. I.
[0023] Fig. 7A is an enlarged detail view of the region 3 of Fig. 1 of
another
example not attached to a riser, using mastic with no elastic seal.
[0024] Fig. 7B is the example of Fig. 7A attached to a riser.
[0025] Fig. 8 is an enlarged detail view of the region 4 of Fig. 2 of
another
example not attached to a riser.
[0026] Fig. 9 is an enlarged detail view of the region 4 of Fig. 2 of
another
example not attached to a riser.
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[0027] Fig. 10A is an enlarged detail view of the region 3 of Fig. 1
of another
example not attached to a riser using an elastic seal an no mastic.
[0028] Fig. 10B is the example of Fig. 10A attached to a riser.
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DETAILED DESCRIPTION OF THE DISCLOSURE
[0029] Manhole casings such as disclosed in U.S. Patent No.
1,712,510
generally comprise a bottom section (1) with a plurality of risers (7) and (8)
attached thereto with a manhole cover (18) or lid attached thereto. These
manholes allow for access via removal of the manhole cover (18) to a system of
fluid conduits (5, 6) which are connected via the open region of the bottom
section (1). The bottom sections of such manholes as shown in this example are
flat and allow for undirected, horizontal flow of fluid from an inlet pipe or
multiple
inlet pipes to an outlet pipe.
[0030] In other applications, it may be desired to form
fluid channels from
the inlet pipes to the outlet pipe. Often, the radial angle, elevation, and
elevation
of each of the inlet pipes and outlet pipe connections to a base may be
aligned
prior to installation of the overall fluid system so as to allow utilization
of pre-set,
precast manhole bases. Many such pre-cast manhole bases can be
manufactured in standard configurations such as straight through, T, cross,
and
other standard configurations. Such standard configurations are especially
useful
where the elevation angle and elevation of the inlet pipes to the outlet pipes
can
be preset prior to installation of the inlet pipe(s) and outlet pipe.
[0031] In some applications, such standard configuration
pre-cast manhole
bases are not financially viable due to the constraints placed by non-standard
radial angle(s), elevation angle(s), and elevation(s) of the inlet pipes and
outlet
pipes. One unknown solution is to form a manhole casing with a (cylindrical)
manhole having a flat (planar) floor. A volume of grout, concrete, or other
aggregate material is then disposed into the manhole base and manually formed
into fluid channels. The term "concrete" is used herein to define a heavy,
rough
building material made from a mixture of broken stone or gravel, sand, cement,
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and water, that can be spread or poured into molds and that forms a stone-like
mass on hardening. Holes are then drilled through the cylindrical manhole base
radially inward upon which couplers may be grouted or otherwise attached to
the
holes drilled through the manhole base at multiple angles to conform to the
requirements of the installation.
[0032] A sanitary sewer is a system of underground pipes
that carries
sewage from bathrooms, sinks, kitchens, and other plumbing components to a
wastewater treatment plant where it is filtered, treated and discharged. A
storm
sewer is a system designed to carry rainfall runoff and other drainage to a
location where it may be treated, such as by allowing sediments to settle out
before the water is discharged.
[0033] One additional detriment of sanitary sewers over
storm sewers is
that sanitary sewer systems are prone to corrosion chemicals which may corrode
the linings and structures of many materials commonly found in the
construction
of manholes, such as concrete, etc.
[0034] Manhole assemblies have been found to typically
experience
significant interior corrosion and deterioration. Nevertheless, hydrogen
sulfide,
which is common in sewage, is developed due to the presence of sulfur
compounds, such as sulfate, sulfite, or other inorganic or organic sulfur.
These
compounds are reduced to sulfide by sulfate-reducing bacteria normally found
in
the effluent. The generation of hydrogen sulfide is accelerated in the
presence of
high temperature and low flow rates.
[0035] Coatings have been applied to the inner surfaces of
manhole
assemblies, but have not been reliable, and are time consuming and expensive.
[0036] Linings of plastic material, such as polyvinyl
chloride (PVC), applied
to the inner surface of a concrete structure are known to provide corrosion
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resistance for interior corrosion protection against hydrogen sulfide. Such
plastic
linings are further compatible with plastic pipe now being used extensively in
sanitary systems. To date, however, it is extremely difficult to fabricate
interior
linings and integrate such interior linings into vertical structures and
particularly
manhole assemblies. Flexible type linings are presently used in pipes covering
the upper 2700 of the pipe interior. This portion is attacked by the H2S
generated
from sewage. This flexible material is not easily used on manholes which
require
360 protection for the manhole interior.
[0037] U.S. Pat. No. 4,751,799, issued June 21, 1988, and
U.S. Pat. No.
5,081,802, issued January 21, 1992, disclose liners formed of a rigid or semi-
rigid material. These liners are fabricated in sections and applied post
production
as a corrosive seal to the structural component which is most commonly an
aggregate (concrete). The aggregate/concrete portions of this disclosed
apparatus in one example conforming to ASTM C478. Generally, each liner
section comprises a curved molded member which may, for example, be thermo-
formed. Each molded member is provided with a means for securing the liner
into
the aggregate (concrete) structure. The liner sections are joined together via
a
bell at the upper end, and a spigot at the bottom end, these connections are
generally caulked or otherwise sealed along their engaging edges. The
projections of ducktail cross-section extend outwardly from the convex
surfaces
of the mold members which are arranged with an interior mold assembly and are
either joined against the surface of an interior mold member by standard
plastic
banding or are alternatively joined together end-to-end by individual holding
members. These assemblies have been found to lack suitable structural strength
and present additional problems in their handling and assembly. In addition,
the
caulking material has been found to provide unsatisfactory waterproof seams
within the manhole assembly structure.
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[0038] One detriment of pre-cast/grouted/drilled construction methods
is that
due to the nature of construction, fluid may enter between the pre-cast
concrete
sections, causing an unsanitary situation when infiltration is not treated and
potentially causing damage should the fluid expand in this gap such as by
freezing thus cracking the casing, cap, and/or the cylindrical base. Disclosed
herein, beginning with Fig. 1, is shown a manhole assembly 20 including
manhole base 22, cap risers, and manhole cap particularly formed using a
method which allows for one-off or individual casting of the manhole base 22
and
other components with improvements over prior construction methods. One such
method is disclosed in US Patent Application 15/367,121 (The '121 Application)
filed on December 1, 2016 which may be referred to for further details.
[0039] The manhole assembly and several methods of manufacture will
be
described in much more detail below, with reference to a base manufactured in
one example according to the disclosure of the '121 Application.
[0040] The manhole assembly 20 in this disclosure includes the base
22, a
riser 24 and a manhole cap 54 including the cover assembly 26. The cover
assembly 26 is normally at ground level 28 so as to be easily accessed by
personnel needing access to the fluid channels therein and fluid conduits
extending therefrom. Commonly, the cover assembly 26, including the removable
cover 30, is disposed in a roadway or sidewalk for easy access. Often, the
cover
assembly 26 with removable cover 30 is formed of cast iron. So as to maintain
a
planar upper surface with the surrounding ground level, the cover 30 generally
fits within a recess 32 of an upper ring assembly 34 and has an upper surface
coplanar or substantially coplanar with the ground lever adjacent thereto. In
one
installation, the upper ring assembly 34 is attached to or formed with one or
more
risers 36 so as to correctly positon the upper surface of the cover 30 at
ground
level.
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[0041] In use, the manhole assembly 20 is assembled within an
excavation
38. Once the manhole base 22 is installed, inlet pipe(s) 40 and/or an outlet
pipe
42 may be attached to the manhole base 22. The excavation 38 outside of the
manhole assembly 20 is then back-filled up to the ground level 28,
substantially
burying the manhole assembly 20 except normally for the cover 30. Access to
the interior of the manhole assembly 20 and components thereof may then be
achieved by way of the cover 30.
[0042] Also shown in Fig. 5 is a plurality of fluid channels 44.
These
channels 44 are commonly open-topped fluid conduits which connect inlet pipes
40 to the outlet pipe 42 and allow access thereto.
[0043] In most examples, each of the fluid channels 44 connects to
either an
inlet pipe 40 or outlet pipe 42. Generally, each inlet pipe 40 and outlet pipe
42 is
aligned with a penetration 46 through the manhole base 22. Lateral connections
may also be made through the manhole cap 54, or through the riser 24. As
shown, one or more of the penetrations 46 may have a coupling such as a bell
connector 48 and/or flexible entry boot or funnel attached thereto allowing
for
easy installation of an inlet pipe 40 or outlet pipe 42. Generally, the bell
connector 48 or funnel includes a compression seal gasket ensuring a fluid
tight
seal between the pipe and the channel penetration 46.
[0044] As can be seen in the examples, a bench 50 is provided on an
upper
surface of the manhole base 22. The bench 50 being substantially horizontal,
in
one example with a slight radial angle downwards toward the center to allow
fluids thereon to flow into the fluid channel 44. The bench 50 may be provided
to
distinguish individual channels, and to provide a surface upon which users can
stand so as to be clear of the fluid passing though the fluid channels 44. In
this
example, the bench 50 is separated into separate regions which may include a
non-skid surface thereupon where a person may stand. Commonly, a user
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entering the manhole assembly 20 will stand upon the bench 50 during
inspection and/or maintenance or cleaning of the interior surfaces and
components of the manhole assembly 20. Thus, a nonskid surface may be
desired to reduce slippage. This non-skid surface may be formed during
production of a liner as disclosed in the '121 application, or may be formed
directly on the casting material in examples where no liner is used.
[0045] Disclosed in the '121 Application, the example manhole base
22,
risers 36, and cap shown comprises a cast, aggregate wastewater manhole with
a material comprising chemically resistant polypropylene (PP), polymerized
vinyl
chloride (PVC), high density polyethylene (HDDPE), fiberglass reinforced
plastics
(FRP) thermoplastic, or other corrosive-resistant material. This corrosive-
resistant material forming a corrosive protective liner (CPL) 52 on the base
22, or
a CPL 56 on the inner surface of the cap 54. In non-corrosive applications,
the
manhole base 22 may not utilize a non-corrosive liner, such as for example
stormwater application. In one example, the coating thickness is in a range
from
0.12"¨ 0.20" (3 ¨ 5mm), mechanically bonded with the concrete base, cap, or
cap riser structure during the precast concrete process disclosed in the '121
Application. The term precast indicating that the disclosed manhole base 22
and/or other separate components are cast (formed, manufactured, produced)
prior to installation at an excavation.
[0046] By casting the entire interior structure and surface of the
manhole
base 22 in one piece with a corrosive-resistant liner 52, and separately
casting
the manhole cap 54 with a similar liner 56, with substantially no post
installation
grouting of channels and/or couplers in that these components and the sealed
liner are produced in the casting process, the disclosed manhole assembly 20
demonstrates design criteria essential for long term protection and efficient
stormwater, wastewater, sewage, and other fluid transmission.
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[0047] The disclosed apparatus forms a unique solution for corrosion,
abrasion, exfiltration, inflow, and/or infiltration.
[0048] Several examples of the disclosed apparatus formed using the
disclosed construction method also provide ease of installation. The joints
between the manhole base 22, riser 24, manhole cap 54, cap risers 36, and
cover assembly 26 may be assembled with a fluid impervious seal using a
capped heated extrusion weld, butyl caulking, flexible joint seal, or other
methods. Once the manhole assembly 20 with a manhole base 22, riser 24, cap
54, and cover assembly 26 is installed it is ready to be put into service,
often
without any sealant cure time required. The disclosed manhole assembly 20
provides water-tight connections which resist settling, expansion and
contraction
stresses after the manhole has been installed.
[0049] Adherence to municipal design standards and allowances for
inflow
and infiltration (I&I) in sanitary and wastewater sewage systems can be
accomplished with the disclosed manhole assembly 20 and production method.
[0050] The optional non-skid surfaces on the bench portions 50 of the
disclosed manhole base 22 may be made of, or coved with, a corrosive-
resistant,
textured layer; they are safe and secure for maintenance staff in a confined,
difficult working environment.
[0051] As previously disclosed, a high strength mechanical bond may
be
achieved by using aggregate and steel lattice or similar anchoring systems.
Pipe
penetrations 46 and optional connectors such as, for example, bell connectors
48
may be molded for specific installation configurations during
manufacturing/casting of the manhole base 22. This molding of the penetration
and/or bell connector often negates the need to field core (drill) and attach
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ancillary connections after casting. Installation time and costs are
substantially
reduced by molding the connections into the manhole base 22.
[0052] In one example production method as disclosed in the '121
application, concrete or other casting material is poured around a pre-formed
corrosive-resistant liner and male mold assembly while the liner and male form
of
the manhole base 22 is in an inverted position; the cap 54 and cap risers 36
may
be made by the same process, in an upright orientation when cast. In one
example the casting exceeds a minimum 4000 P.S.I. casting. In one example, a
high-strength mechanical bond between the corrosive-resistant liner and
concrete is achieved by way of a well-proven interface consisting of
specifically-
sized clean aggregate and steel coil/lattice bonded to the bottom of the
liner.
With vibrated concrete attaching itself to this continuous multi-faceted
bonding
medium, intruding forces of groundwater backpressure is not of concern.
[0053] The disclosed manhole base 22 with an optional liner is a
component
of a manhole base assembly 20 for new manhole construction or for manhole
rehabilitation. Microbial induced corrosion (MIC) has been increasingly
evident in
concrete manhole casings and related sanitary sewer structures for decades.
MIC occurs when sulfuric acid, generated from raw sewage, reacts with the
properties of cement to diminish the integrity of concrete manhole bases and
related structures.
[0054] Hydrogen sulfide (H2S), in anaerobic and aerobic forms, has
the
capacity to severely damage concrete components. Prior to 1980, heavy metals
in wastewater retarded the growth of bacteria in sewer systems, minimizing
MIC.
Since the US Clean Water Act (1980) mandated the elimination of certain toxic
heavy metals ¨ lead, chromium, mercury, arsenic, cadmium ¨ from wastewater,
effluent MIC has reached acute levels in sanitary and wastewater sewage
systems; these heavy metals are toxic to humans and other life forms,
including
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bacteria. Now, bacterial colonies flourish and assist with the generation of
H2S
gas and, with oxidation, H2SO4. Acidic deterioration of sanitary sewer
pipelines
and manholes has increased substantially. Coating systems that once protected
concrete structures are known to fail. Splash and turbulent water flow
exacerbate
the destructive effect on concrete manholes. More aggressive corrosion can be
expected when septic conditions exist, which may also result in leaking pipe
connections. Other contributing factors, such as drop connections or a large
number of entry points introduced into the structure, create more acid
corrosion
problems.
[0055] The disclosed method and manhole assembly 20 improves
resistance to MIC by removing any gaps between the channel body and the outer
wall. The optional gapless liner covering the channel body of the base,
utilizing a
riser 24 with no concrete or similar composition also improves resistance to
MIC.
[0056] These new conditions require revised design parameters for
many
components in the sewage transmission system, including manholes. Liner
material, such as fiberglass reinforced plastic (FRP) and polypropylene (PP),
can
be applied to newly poured concrete to provide a dense, impervious and
continuous corrosive-resistant lining for the manhole base 22, cap 54, and/or
cap
risers 36 to protect the concrete substrate from destructive acid attack. This
deteriorated concrete condition can be prevented in one example with
thermoplastic barriers that isolate the sewage from the concrete components of
the manhole assembly 20, or using non-concrete materials.
[0057] As evidenced by the anaerobic process, the eventual
disintegration
of the concrete components of a manhole assembly 20 is often the result of a
hydrogen sulfide attack. More aggressive corrosion can be expected when septic
conditions exist, which may also result in leaking pipe connections. Other
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contributing factors, such as drop connections or a large number of entry
points
introduced into the structure, create more acid corrosion problems.
[0058] The disclosed manhole base 20 and construction method ensures
complete coverage of the channel body, and gapless attachment of the liner to
the concrete casting.
[0059] Looking to Figs. 1, 2, and 4 are shown cross-sectional views
of a
manhole assembly 20 using the disclosed apparatus. In this example, the
manhole base 22 has a radial recess or spigot 58 in the upper, radially
outward
edge thereof. This spigot 58 having a substantially vertical surface 60 and a
horizontal surface 62 cooperating to form the spigot 58 for receiving the
riser 24.
In one example, the surface 60 is tapered inward to allow for easier
connection to
the riser 24. In one example the taper is between 10 and 50. The riser 24
resting
solely on the bottom surface 62 of the spigot 58 and not engaging the upper
surface 50. In one example an ASTM C443-compliant gasket 66 is applied
between the radially inner surface 64 of the riser 24 and the vertical surface
60 of
the spigot 58. In one example a Hamilton Kent Tylox TM Type "C" gasket model
#5796 is used as the gasket 66. In another example, an ASTM C990 "Mastic"
joint may be utilized instead of or in combination with a gasket 66.
[0060] One additional advantage of using a spigot 58 on the base 22,
and a
spigot 80 on the cap 54 is that such large diameter pipes forming the riser 24
are
generally cylindrical and often not perfectly cylindrical. Deformation may
occur
during manufacture, during cooling, transport, and/or storage. The disclosed
apparatus allows for easy attachment of the base 22, riser 24, and cap 54 and
the riser will be pressed back into a cylinder at the connection ends by the
spigots 58/80. In examples using an angled spigot, as shown in the example of
Fig. 4B, this is even more easily accomplished. In the example shown, the
angle
110 between the inner surface of the riser and the vertical surface 60 of the
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spigot may be between 1 and 100. In one example and angle of between 2 and
. This may also be achieved by chamfering the inner surface or bottom inner
edge 112 of the riser 24 as also shown in Fig. 4.
[0061] In addition, a seal 68 may be used between the longitudinally
bottom
edge 70 of the riser 24 and the bottom surface 62 of the spigot 58. This seal
68
may be a fluid component such as grout, fluid silicone, mastic, etc., or a
manufacture's seal such as rubber tape, rolling tube seal, etc.
[0062] The disclosed connection between the riser 24 and the manhole
base 22 in one example provides for a smooth outer surface transition between
the base 22 and the riser 24 which allows for the use of an ASTM C877-
compliant external joint wrap ( which seals to the outer surface of the base
22
and the riser 24, hindering fluid passage. The joint wrap 72 extends
circumferentially around the base 22 and the riser 24 sealing the outer
surfaces
of the two components. The joint wrap 72 may be tape, polymer films, silicone,
hardening fluids, resin impregnated fabrics, and combinations thereof. Looking
to
Fig. 2 for example, it can be seen that the radially outward surface 76 of the
riser
24 is aligned with the radially outward surface 78 of the manhole base 24.
Prior
known installations using a bell on the base required a larger outer diameter
on
the base than the riser, commonly precluding application of an external joint
wrap
72.
[0063] In one example, the manhole base 22 is cast of steel
reinforced, cast
monolithic with an integral corrosion resistant liner. In one example the
liner is
corrosion resistant, for example resin hardened fiberglass. In one example the
manhole base 22 incorporates compression gasket pipe connections which are
ASTM C923-compliant.
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[0064] In one example, no structure is required outside of the pipe's
OD,
thus the overall outside diameter of the manhole assembly 20 relative to known
assemblies using a bell on the base and/or cap is reduced from 58" to 51" for
a
common 48" ID Manhole. This represents a 23% reduction in footprint,
translating directly into less concrete required to construct the manhole
assembly.
[0065] Commonly, PVC manhole riser pipe comes from the manufacturer
in
22' lengths, meaning that up to a 25' deep MH can be constructed with a Base
(-1.5'), Riser (< or = 22'), and cover assembly 26 with hat 96 + cover 30 (-
1.5').
Such PVC pipe can be ordered in lengths greater than 22' if required for a
deeper manhole than 25' (which is 95% of all manholes).
[0066] 48" precast concrete manhole risers weigh ¨800# per vertical
foot.
Typically they are manufactured in 1' increments up to 4' and are stacked one
on
top of the other in the field to achieve the desired height (depth). Each
joint
requires extra sealant, labor & materials, and is a potential source of
infiltration or
exfiltration. Typical precast manholes have 3 or more joints, where the
manhole
assembly 20 disclosed herein has only 2.
[0067] 48" PVC MH Risers weigh approximately 110 pounds per vertical
foot. Typically manufactured in 22' lengths and are cut to length in the field
to
achieve the desired height (depth). Typical PVC manholes only have 2 joints,
reducing labor, materials, and infiltration/exfiltration points.
[0068] Similarly, an internal seal 74 may be added, such as grout,
silicone,
polymers, or other materials added after connection of the riser 24 to the
inner
surfaces of the riser 24 and the inner surface of the manhole base 22.
[0069] Figs. 1, 2, and 3 show a similar attachment of the manhole cap
54 to
the riser 24 where the manhole cap 54 comprises a radially outer and
vertically
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lower edge forming a spigot 80 having a radially inner surface 82 facing the
inner
surface 64 of the riser 24 and an upper surface 84 resting on the longitudinal
end
86 of the riser 24. Thus, the entire weight of the cap 54 rests on the end
surface
of the riser 24 and no bell is required.
[0070] In one example an ASTM C443-compliant gasket 88 is applied
between the radially inner surface 64 of the riser 24 and the vertical surface
82 of
the spigot 80. In one example a Hamilton Kent Tylox TM Type "C" gasket model
#5796 is used as the gasket 88. In another example, an ASTM C990 "Mastic"
joint may be utilized instead of or in combination with a gasket 88.
[0071] Where the fluid level in the fluid channels 44 is unlikely to
rise to the
level of the spigot 82, the gasket 88 may be omitted.
[0072] As with the connection between the manhole base 22 and the
riser
24, the connection between the manhole cap 54 and the riser 24 may be sealed
with a seal 90 positioned used between the longitudinally upper edge 86 of the
riser 24 and the surface 84 of the spigot 80. This seal 90 may be a fluid
component such as grout, fluid silicone, mastic, etc., or a manufacture's seal
such as rubber tape, rolling tube seal, etc.
[0073] The disclosed connection between the riser 24 and the manhole
cap
54 in one example provides for a smooth outer surface transition between the
manhole cap 54 and the riser 24 which allows for the use of an ASTM C877-
compliant external joint wrap 92 sealing to each of the manhole cap 54 and the
riser 24, hindering fluid passage. The joint wrap 92 extends circumferentially
around the cap 54 and the riser 24 sealing the outer surfaces of the two
components. The joint wrap 92 may be tape, polymer films, silicone, hardening
fluids, resin impregnated fabrics, and combinations thereof. Looking to Fig. 2
for
example, it can be seen that the radially outward surface 76 of the riser 24
is
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aligned with the radially outward surface 94 of the manhole cap 54. Prior
known
installations using a bell on the manhole cap required a larger outer diameter
on
the manhole cap than the riser, commonly precluding application of an external
joint wrap 92.
[0074] In one example, the riser 24 is a length of straight pipe
formed of a
corrosive-resistant material. Such pipes generally coming in straight lengths
using additional connectors, or a bell/spigot pipe having a bell connector on
one
end and a spigot on the opposing end. By utilizing a straight pipe, with
spigots on
each of the base and cap, the bell may be omitted from the pipe. The riser 24
may comprise chemically resistant polypropylene (PP), polymerized vinyl
chloride (PVC), high density polyethylene (HDDPE), steel, lined steel,
stainless
steel, copper. brass, fiberglass reinforced plastics (FRP) thermoplastic, or
other
corrosive-resistant material with similar load bearing (structural)
characteristics.
In one example the riser is monolithic, consisting of one unbroken,
unsegmented
material. By so forming the manhole assembly 20 with a monolithic riser 24,
the
outer diameter, weight, and other benefits are accomplished.
[0075] In addition, root intrusion is reduced in that joints between
riser
sections are eliminated. In one example, the main joints are first between the
manhole cap 54 and the riser 24, and second between the riser 24 and the
manhole base 22.
[0076] One significant advantage of this over other known
installations, such
as that utilized by the Ipex TM company, is the use of the spigot 58 on the
base,
and a similar spigot 80 on the manhole cap 54 whereas the prior art has
utilized
a bell on the base and a bell on the cap, thus sealing the base and the cap to
the
outer radial surface of the riser sections. The 1pex TM application thus
requiring a
larger excavation, larger/heavier/more difficult to install or transport
manhole
base and cap.
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[0077] In one example, the gaskets 66 and 82 are secured to the
manhole
base 22 and manhole cap 54 prior to connection to the riser 24.
[0078] Testing has shown that the wraps 72/92 are sufficient for
sealing the
components, and the gaskets 66, 82, 68, and 90 are not required for sealing of
the manhole assembly 20. In some jurisdictions, such gaskets are legally
required. In one example, the gaskets 66, 82, 68, and 90 extend
circumferentially
about the components between which they seal.
[0079] Figs. 1, 2, 3, and 6 also show additional components of the
manhole
assembly 20. These including a sliding or telescoping access collar or (hat)
96.
The sliding hat 96 positionably engaging a surface defining an access hole 98
of
the manhole cap 54. The access hole 98 extending through the manhole cap 54,
hat 96, risers 36, and cover assembly 26. The cover 30 closing the access hole
98 from undesired entry.
[0080] In the example shown, the hat 96 comprises a cylinder 100 and
a
radially protruding rim 102. The rim 102 resting on the manhole cap 54, or on
a
riser 36 when risers are used. The cover assembly 26 resting above the rim 102
and in some applications attached thereto.
[0081] The cylinder 100 having a radially inward surface providing
part of
the access hole 98, and a radially outward surface 106 adjacent to or in
contact
with a radially inward surface 104 of the hat 96. This arrangement allowing
for
vertical positioning of the hat 96 relative to the manhole cap 54 and allowing
for
risers 36 and vertical adjustment thereof such as by application of spacers,
grout,
etc. to raise the cover assembly 26 to the ground level 28 as previously
discussed.
[0082] In one example, a gasket 108 is attached to the inner surface
98 of
the manhole cap 54 and sealed to the outer surface 106 of the hat 96. This
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providing a sliding seal between the hat 96 and the, manhole cap 54 hindering
fluid there past.
[0083] Fig. 2 also shows a plurality of lifting components 114 cast
into the
manhole base 22 and manhole cap 54. These lifting components 114 may be
substantially equivalent to those disclosed in US Patent 3,499,676 which may
be
referred to for further details. These lifting components 114 allow the
manhole
base 22 and manhole cap 54 to be independently lifted, carried, and stored
without impact damage to manhole base 22 or manhole cap 54.
[0084] In the example shown in Fig. 2, and Fig. 5, the lifting studs
114
(114a-114c) protrude outward from the manhole base 22 and manhole cap 54.
This is to allow easy attachment of lifting devices such as chains, ropes,
straps,
cables, connectors etc. Thus, in one example a lifting connector 116 having a
first end 118 attached to a lifting stud 114 of the manhole cap 54 and a
second
end 120 attached to a lifting stud 114 of the manhole base 22. As the lifting
studs
114 of the manhole cap 54 are attached to a lifting device and raised, the
lifting
connector 116 is put in tension and transmits the lifting force to the manhole
base
22. Thus as the manhole cap 54 is lifted, the riser 24 and manhole base 22 are
also lifted.
[0085] In one example, the lifting connector 116 is a length of rigid
material.
In one example the lifting connector 116 is a length of metal. In one example
the
lifting connector 116 is a length of U-channel.
[0086] To facilitate attachment of each lifting connector 116 to the
manhole
base 22 and manhole cap 54 the lifting connector may have surfaces defining
holes 122 there though at the first end 118 and the second end 120. A portion
of
a bolt, protrusion, or the lifting studs 114 pass through the surfaces
defining
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holes 122 and maintain the lifting connector 116 in position and allow
transference of the lifting force.
[0087] In one example, the lifting studs 114 have a male threaded
end,
threaded into a female threaded insert within the manhole base 22 and / or
manhole cap 54. Thus, the lifting studs 114 pass through the holes 122 and are
threaded into the female receivers. In one example, the female receivers are
cast
into the manhole base 22 and / or manhole cap 54.
[0088] The lifting connectors 116 also providing structural support
to the
manhole assembly 20 by securing the base, riser, and cap in relative position.
In
several environmental conditions, such a structural connection is particularly
useful. First; where there is a condition of high ground water, the components
may tend to "float" or reposition and thus become detached. Second; earth
movement (e.g. earthquake) may cause the components to become detached
without some structural connection. Third; when the surrounding ground
freezes,
causing "frost heave" may cause the components to become detached.
[0089] In addition, the listing connectors 116 may intermittently or
consistently provide compression strength to the manhole assembly 20. For
example, a heavy vehicle driving over the manhole assembly 20 in the ground
may impart a substantial compression load on the riser 24. The lifting
connectors
116 in such a situation will resist compression and provide compression
strength
to the manhole assembly 20.
[0090] The following definitions are used in this disclosure:
[0091] Bell and Spigot: A connection between two sections of pipe, or
between a pipe and a connector, or between two fluid connectors. The straight
"spigot" end of one section is inserted in the flared-out "bell" end of the
adjoining
section; the joint is sealed by a caulking compound or with a compressible
ring.
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[0092] Bell: a pipe connection having an inner radial surface which
is larger
in diameter than the inner radial surface of the adjacent portion of the
connection.
The radial outer surface of a pipe or connector has an outer end surface which
contacts the inner radial surface of the bell and forms a fluid connection
thereto.
[0093] Spigot: a pipe connection having an outer radial surface which
fits
into an inner radial surface "bell" of a connecting fluid conduit and forms a
fluid
connection thereto.
[0094] Tapered: to diminish or reduce in thickness toward one end.
[0095] Aggregate: any of various loose, particulate materials, as
sand,
gravel, or pebbles, added to a cementing agent to make concrete, plaster, etc.
[0096] While the present invention is illustrated by description of
several
embodiments and while the illustrative embodiments are described in detail, it
is
not the intention of the applicants to restrict or in any way limit the scope
of the
appended claims to such detail. Additional advantages and modifications within
the scope of the appended claims will readily appear to those sufficed in the
art.
The invention in its broader aspects is therefore not limited to the specific
details,
representative apparatus and methods, and illustrative examples shown and
described. Accordingly, departures may be made from such details without
departing from the spirit or scope of applicants' general concept.
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