U.S. patent application number 10/822520 was filed with the patent office on 2004-09-30 for underground storage tank.
Invention is credited to Bolzer, Todd.
Application Number | 20040188447 10/822520 |
Document ID | / |
Family ID | 32993319 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040188447 |
Kind Code |
A1 |
Bolzer, Todd |
September 30, 2004 |
Underground storage tank
Abstract
An underground storage tank includes a shell provided with an
outer wall which is molded to include a plurality of longitudinally
spaced, opposed pairs of receiving pockets which extend inwardly
from the outer surface of the outer wall. Internal reinforcements
may be provided either as tubular members mounted within the shell
on reinforcement mounts molded into the pockets, or as tubes molded
into the shell. The reinforcements are positioned within the
chamber of the tank and resist deformation by maintaining the
opposed pairs of pockets in spaced-apart relationship.
Stabilization lugs are molded into the shell at corners adjacent
each of the longitudinally spaced generally dome-shaped ends. A
manway has an upwardly extending collar for receiving a cover
thereon, and a circumscribing trough for isolating the collar
against deformation.
Inventors: |
Bolzer, Todd; (Jonesboro,
AR) |
Correspondence
Address: |
HOVEY WILLIAMS LLP
Suite 400
2405 Grand
Kansas City
MO
64108
US
|
Family ID: |
32993319 |
Appl. No.: |
10/822520 |
Filed: |
April 12, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10822520 |
Apr 12, 2004 |
|
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10055440 |
Jan 23, 2002 |
|
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60461849 |
Apr 10, 2003 |
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Current U.S.
Class: |
220/653 |
Current CPC
Class: |
B65D 90/105 20130101;
B29C 41/04 20130101; B65D 88/76 20130101; B65D 88/06 20130101; B65D
90/027 20130101 |
Class at
Publication: |
220/653 |
International
Class: |
B65D 088/00 |
Claims
1. An underground storage tank comprising a synthetic resin shell
having an outer wall and defining a chamber therein for the receipt
and storage of liquid, the shell being generally elongated along a
longitudinal axis and having a height and a width oriented at
orthogonal axes generally transverse to the longitudinal axis, said
outer wall including an upper wall having structure defining at
least one manway for permitting entry into and egress from the tank
and a lower wall, the outer wall of the shell having a plurality of
inwardly extending receiving pockets, at least two of the receiving
pockets being positioned in opposition to one another, each of said
receiving pockets having an upright wall extending at least about
15% of the height of the shell and a second wall substantially
perpendicular to the upright wall and extending at least about 15%
of the width of the shell.
2. An underground storage tank as set forth in claim 1, wherein
said upper wall includes a first set of said plurality of receiving
pockets arranged in longitudinally spaced relationship, wherein
said outer wall intermediate the receiving pockets of said first
set of said plurality of receiving pockets is generally arcuate
when viewed along the longitudinal axis.
3. An underground storage tank as set forth in claim 2, wherein
said upper wall includes a second set of said plurality of
receiving pockets positioned laterally opposite said first set of
said plurality of receiving pockets.
4. An underground storage tank as set forth in claim 3, wherein
said lower wall includes third set of said plurality of receiving
pockets positioned substantially beneath said first set of said
plurality of receiving pockets and said second set of said
plurality of receiving pockets in said upper wall.
5. An underground storage tank as set forth in claim 3, wherein at
least some of said first and second set of receiving pockets have
their upright walls oriented in planes which intersect a plane
extending substantially vertically through said longitudinal
axis.
6. An underground storage tank as set forth in claim 2, wherein
said lower wall includes a second set of said plurality of
receiving pockets positioned substantially beneath said first set
of said plurality of receiving pockets.
7. An underground storage tank as set forth in claim 6, wherein
said outer wall longitudinally intermediate the receiving pockets
of said second set of said plurality of receiving pockets is
generally arcuate when viewed along the longitudinal axis.
8. An underground storage tank as set forth in claim 6, wherein the
receiving pockets each include a pair of opposed, substantially
upright side walls and an upright inboard wall connecting the
upright side walls, and a base wall extending substantially
transversely to said side walls and said upright inboard wall.
9. An underground storage tank as set forth in claim 1, wherein
said shell includes opposed, longitudinally spaced substantially
dome-shaped end walls.
10. An underground storage tank as set forth in claim 1, wherein
said end walls include at least one upright substantially flat
surface extending over a majority of the height of said shell.
11. An underground storage tank as set forth in claim 1, wherein
said shell includes at least one laterally projecting stabilization
lug integrally formed with said outer wall, said stabilization lug
including at least upright opening therethrough.
12. An underground storage tank as set forth in claim 11, wherein
said stabilization lug includes a first arm extending substantially
horizontally substantially parallel to said longitudinal axis and a
second arm extending substantially horizontally and substantially
perpendicular to said longitudinal axis.
13. An underground storage tank as set forth in claim 12, wherein
said stabilization lug has a hollow interior which fluidically
communicates with said chamber.
14. An underground storage tank as set forth in claim 1, wherein
said upper wall includes a collar surrounding said manway and a
circumscribing trough surrounding said collar, said circumscribing
trough communicating with at least one of said receiving pockets
for enabling liquid collected in said recess to drain into said at
least one of said receiving pockets.
15. An underground storage tank as set forth in claim 1, wherein
said upper wall includes an upwardly projecting lug presenting an
opening transversely extending therethrough and an adjacent recess
in said upper wall, whereby said recess is complementally located
relative to said upwardly projecting lug to receive said lug
therein when two of said storage tanks are positioned with their
upper walls in adjacency.
16. An underground storage tank as set forth in claim 1, wherein
said outer wall includes an upper wall which includes a first set
of said receiving pockets, said shell further including a lower
wall having a second set of said receiving pockets positioned
substantially beneath said first set of said receiving pockets to
provide superposed pairs of upper and lower receiving pockets, at
least one of the receiving pockets of said first set of said
receiving pockets and at least one of the receiving pockets of said
second set of receiving pockets including an opening therein, and
further including a tubular member integrally formed with said
outer wall and extending between at least one of said superposed
pairs of upper and lower receiving pockets having said openings in
the respective receiving pockets thereof, said tubular member
fluidically communicating with said openings to permit the passage
of liquid therethrough and to isolate the chamber from liquid
passing through said tubular member.
17. An underground storage tank as set forth in claim 16, wherein
each of said superposed pairs of receiving pockets includes
openings therein and having one of said tubular members extending
between said openings.
18. An underground storage tank as set forth in claim 17, wherein
said tubular member is substantially frustoconically shaped.
19. An underground storage tank as set forth in claim 18, wherein
the openings in the receiving pockets of the first set of receiving
pockets has a greater transverse dimension than the openings in the
receiving pockets of the second set of receiving pockets.
20. An underground storage tank as set forth in claim 16, wherein
said tubular member includes a waist portion intermediate the
openings of the receiving pockets, said openings of the receiving
pockets having a first area and the waist portion of the tubular
member having a second area smaller than the first area.
21. An underground storage tank as set forth in claim 1, wherein
said shell includes a lower wall and a side wall positioned
intermediate said upper wall and said lower wall, said shell
further including a plurality of longitudinally spaced
substantially upright ribs molded into said side wall.
22. An underground storage tank as set forth in claim 21, wherein
said ribs are defined by slots molded into said outer wall
projecting inwardly into said chamber.
23. An underground storage tank as set forth in claim 22, wherein
said slots extend from said side wall into said upper wall and said
lower wall.
24. An underground storage tank as set forth in claim 23, wherein
at least one of said slots is positioned to communicate with one of
said receiving pockets.
25. An underground storage tank as set forth in claim 24, wherein
said upper wall includes a first set of said plurality of receiving
pockets arranged in longitudinally spaced relationship and said
outer wall intermediate the receiving pockets of said first set of
said plurality of receiving pockets is generally arcuate when
viewed along the longitudinal axis, wherein said lower wall
includes a second set of said plurality of receiving pockets
positioned substantially beneath said first set of said plurality
of receiving pockets, and wherein at least some of said slots
communicate between respective receiving pockets in said first set
and said second set.
26. An underground storage tank as set forth in claim 25, wherein
additional slots are positioned in said outer wall intermediate the
receiving pockets of said first set of receiving pockets.
27. An underground storage tank as set forth in claim 1, wherein
said upper wall includes a first set of said plurality of receiving
pockets arranged in longitudinally spaced relationship, wherein
said outer wall intermediate the receiving pockets of said first
set of said plurality of receiving pockets is generally arcuate
when viewed along the longitudinal axis said upper wall includes a
second set of said plurality of receiving pockets positioned
laterally opposite said first set of said plurality of receiving
pockets, and further including at least one transverse rib
extending across said upper wall and between respective ones of
said first set of receiving pockets and said second set of
receiving pockets.
28. An underground storage tank as set forth in claim 27, wherein
said transverse rib is formed by a slot molded into said upper
wall.
29. An underground storage tank as set forth in claim 1, wherein
said outer wall includes an upper wall which includes a first set
of said receiving pockets, said shell further including a lower
wall having a second set of said receiving pockets positioned
substantially beneath said first set of said receiving pockets to
provide superposed pairs of upper and lower receiving pockets, at
least one of the receiving pockets of said first set of said
receiving pockets and at least one of the receiving pockets of said
second set of receiving pocket forming an opposing superposed pair
having a reinforcement mount wherein said reinforcement mounts of
said opposing superposed pair are oriented in opposition to one
another, and further including a reinforcement member constructed
separately from said shell and mounted on said reinforcement mounts
between said opposing superposed pair.
30. An underground storage tank as set forth in claim 29, wherein
said reinforcement member is tubular.
31. An underground storage tank as set forth in claim 30, wherein
said reinforcement includes at least one perforation therein for
permitting liquid to flow into and from the reinforcement.
32. An underground storage tank as set forth in claim 29, wherein
said superposed pairs of receiving pockets are longitudinally
spaced from one another.
33. An underground storage tank as set forth in claim 29, wherein
superposed pairs of receiving pockets are positioned on both sides
of an upright plane passing through the longitudinal axis of the
tank.
34. An underground storage tank as set forth in claim 29, wherein
the reinforcement mount is molded into the receiving pockets.
35. An underground storage tank as set forth in claim 29, wherein
the manway includes a collar extending upwardly from a
circumscribing trough recessed inwardly and below the upper
wall.
36. An underground storage tank as set forth in claim 35, wherein
the collar includes recesses for receiving a cover thereon in
locking engagement.
37. An underground storage tank as set forth in claim 36, including
a cover received on the manway.
38. An underground storage tank as set forth in claim 8, wherein
said base wall is substantially imperforate and wherein said
upright side walls and said upright inboard walls of said receiving
pockets have a vertical extension such that the base walls of a
respective pair of substantially vertically aligned pockets meet at
a junction therebetween.
39. An underground storage tank as set forth in claim 38, wherein
said junction between said base walls of said receiving pockets is
a molded connection.
40. An underground storage tank comprising: a shell having an outer
wall, the outer wall including an upper side having a top surface,
the outer wall defining a chamber therein; at least one manway
leading into the chamber, the manway including a collar adapted for
receiving a cover thereon and a circumscribing trough recessed
downwardly from the collar and the top surface of the outer
wall.
41. An underground storage tank as set forth in claim 40, wherein
the shell includes a plurality of receiving pockets recessed
inwardly into the chamber, at least one of the receiving pockets
including an upright wall positioned adjacent to the trough of the
manway whereby liquid collected in the manway may drain into the
receiving pocket.
42. An underground storage tank as set forth in claim 41, wherein
the shell includes an arcuate, upright shoulder wall extending
downwardly to the trough from the top surface.
43. An underground storage tank as set forth in claim 42, wherein
the shell includes a pair of longitudinally spaced, dome-shaped
ends, each of the ends having an upright panel wall extending
downwardly to the trough and positioned opposite the arcuate,
upright shoulder wall.
44. An underground storage tank as set forth in claim 40, including
a reinforcement mount integrally molded into each of said receiving
pockets, and a reinforcement mounted on each of said reinforcement
mounts within the chamber which extends between respective
pockets.
45. An underground storage tank comprising a shell molded of
synthetic resin material and having an outer wall defining therein
a chamber, said shell including a pair of longitudinally spaced
ends and at least 1 L-shaped lug molded into the outer wall at each
of said ends presenting an upright opening between said lug and
said shell.
46. An underground storage tank as set forth in claim 45, wherein
said shell includes a vertically extending groove molded therein
and positioned interiorly of said L-shaped lug.
47. An underground storage tank as set forth in claim 45, wherein
said shell is elongated and includes two longitudinally spaced
substantially dome-shaped ends each having at least one flat
surface thereon substantially aligned along an upright plane
passing through a longitudinal axis of the shell, and including a
plurality of said L-shaped lugs positioned to extend from each of
said substantially dome-shaped ends.
Description
[0001] This application claims the benefit of U.S. Provisional
Application Serial No. 60/461,849 filed Apr. 10, 2003, and is a
Continuation-in-Part of application Ser. No. 10/055,440 filed Jan.
23, 2002.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention broadly concerns storage tanks which are
intended for use below grade for receiving and storing liquids and
solids, such as for use as a septic tank, pump tank, dose tank,
holding tank, or cistern. More particularly, it is concerned with
such a tank which may be molded of synthetic resin material and
configured for enhanced structural support and stability.
[0004] 2. Description of the Prior Art
[0005] Underground storage tanks are well known for use as septic
tanks and cisterns. Such tanks have long been constructed of
concrete and metal for their durability and extended life. However,
concrete tanks for storing liquid or septic tank use are heavy and
difficult to place, and maybe subject to leakage over extended
periods due to the shifting of the earth around the tank. Metal
tanks are expensive to fabricate and may be subject to
corrosion.
[0006] More recently, synthetic resin has been used to make
underground storage and septic tanks. Relatively large volume tanks
may be fabricated of fiberglass reinforced plastic, high density
polyethylene and other resilient synthetic resins using rotational
molding techniques. These tanks have significant advantages in
terms of cost and weight, and have proven useful for retaining and
storing water, sewage, and other materials. Examples of synthetic
resin storage tanks useful in water storage and septic tank
applications include those shown in U.S. Pat. Nos. 4,254,885,
4,961,670, 5,242,584, 5,361,930 and 6,328,890, and published U.S.
patent applications US2002-0153380A1 and US2002-0185433A1, the
disclosures of which are incorporated herein by reference.
[0007] One problem encountered during use of most underground
storage tanks is that the synthetic resin tanks may be subject to
deformation caused by a variety of factors. For example, when
filled with water, sewage or other liquid, the load on the tank by
the weight of the contents may cause significant distortion.
Another source of deformation is caused by changes in soil moisture
whereby the earth adjacent the tank may expand and contract. This
may occur unevenly, further complicating the ability of the
synthetic resin tank to withstand deformation caused by these
external forces. Tractors, farm animals and other sources of
surface loading may be transmitted to the underground tank, causing
deformation. In short, a wide variety of differences in internal
and external forces acting on the tank may cause the tank walls to
bend or flex. When significant bending or flexing occurs, the
manhole opening to the tank may deform sufficiently to prevent
attachment of the manhole cover, or cause separation of pipes and
fittings leading to the tank, or under severe loading and
environmental conditions cause cracking of the tank wall. Under
these circumstances, the tank may be rendered inoperative and must
be repaired, if possible, or replaced.
[0008] There has thus developed a need for an improved tank of
synthetic resin construction having an enhanced ability to
withstand internal and external forces without significant
deformation which leads to tank failure.
SUMMARY OF THE INVENTION
[0009] These objects have largely been met by the tank of the
present invention. The tank hereof is designed to resist
deformation, particularly in the region of the manhole opening. In
addition, the tank hereof includes internal reinforcements which
help resist the collapse of the upper wall downwardly toward the
lower wall or upwardly from the lower wall to the upper wall. The
reinforcements may be distributed within the internal chamber of
the tank to maintain the initial shape of the tank even when
subjected to significant external forces and/or filled with liquid.
Further, the tank may be constructed so that the reinforcements do
not significantly affect the capacity of the tank.
[0010] The tank of the present invention includes a shell which is
preferably molded in a unitary member of a synthetic resin
material. The shell is provided with at least one opening.
Preferably, the shell has an opening sufficiently sized to permit
ingress and egress of a human into the chamber within the tank, and
additional openings to permit the attachment of pipes for the
receipt and discharge of liquid, such as water or sewage. The shell
is molded into an elongated shape along a major axis with rounded
ends and when viewed along its major axis, its upper wall is seen
to be generally arcuate and the lower portion of the shell has
arcuate edges with a relatively large radius which aids in
distributing loading on and from within the shell. Furthermore, the
upper wall and lower wall are provided with reinforcing pockets
formed therein which resist deformation when the tank is filled and
placed below ground. The reinforcing pockets are preferably
arranged in sets, whereby the reinforcing pockets in one set are
aligned with respective reinforcing pockets in another set. The
arrangement is most preferably such that a reinforcing pocket may
be aligned both vertically with another reinforcing pocket and
laterally across from another reinforcing pocket formed in the
shell.
[0011] The tank hereof may be constructed with several alternative
ways of reinforcement. In one alternative configuration, the
reinforcing pockets alone are used to maintain the shape of the
tank and resist deformations. In this configuration, the
reinforcing pockets are closed and the tank is configured for
maximum volume, with the shell of the tank resisting deformation.
The reinforcement pockets may also be designed with additional
depth, such that two reinforcement pockets positioned in
substantial vertical alignment are closely proximate or meet at all
or a portion of their base wall, so that the two vertically aligned
reinforcement pockets cooperate with one another to provide mutual
support.
[0012] In a second alternative configuration, the reinforcing
pockets are also closed but configured to act as reinforcing mounts
which project inwardly into the chamber. The reinforcing mounts are
preferably configured and oriented in opposition to one another,
elongated reinforcing members may be coupled to the mounts between
opposing sections of the shell. Thus, the reinforcing mounts are
molded into the wall of the shell and configured to resist collapse
of one part of the wall towards another and do not provide
additional openings into or through the shell. Moreover, the
reinforcing mounts are preferably located at indentations molded
into the tank whereby the indentation walls provide structural
strength and support to the adjacent arcuate portion of the shell
in combination with the internal reinforcements. That is to say,
the indentation walls help carry the loading of the shell along
with the reinforcements such that the shell and internal
reinforcements act in combination.
[0013] In this embodiment, the reinforcements are preferably
discrete members which are mounted on the reinforcing mounts. Most
preferably, the reinforcements are tubular members which may be
cylindrical in configuration and oriented substantially vertically
in use. The reinforcements maybe provided of a chemically resistant
material, such as high density polyethylene, and may be perforated
whereby the capacity of the tank is not substantially reduced by
their inclusion, yet the structural support provided is not
significantly affected. The reinforcements are preferably installed
by obtaining access to the chamber within the shell through manway
openings, and use of a jack, ram or other shiftable member capable
of moving the shell apart between opposing reinforcement mounts,
inserting the reinforcements between the mounts to be received
thereon. Because the load carried by the reinforcements is
primarily compressive, it is not necessary to affix the
reinforcements to the mounts by the application of fasteners such
as screws, bonding agents or thermal bonding, although this can be
done if desired. Most preferably, the mounts include sleeves which
partially extend into each end of the reinforcements to hold the
reinforcements in position against lateral displacement or
dislodgment from the mounts.
[0014] In a third alternative, the reinforcing pockets include
openings therein. The openings communicate fluidically with one
another by molded-in-place columns. The columns are preferably
molded by the use of kiss-throughs in the moulding process, whereby
the columns are formed integrally with the shell. The columns allow
water to drain down through the columns or permit a rising water
table in the earth to rise through the columns while retaining
isolation of the tank contents from such water. It may be
appreciated that the molded-in-place columns may be more
economically molded than the insertion of the interior columns as
described above, but with the consequent disadvantage of loss of
some storage capacity. The columns may be molded to be tapered
along their length so that the columns are generally frustoconical
in configuration. Alternatively, the molded-in-place columns may
present an hourglass-type shape, where they taper to a narrowest
portion intermediate the openings in the upper and lower
reinforcing pockets.
[0015] The shell is preferably configured in an elongated
orientation having modified dome-shaped ends, provided a modified
extended spherical configuration. Stabilization lugs, as shown in
my pending U.S. patent application Ser. No. 10/055,440 filed Jan.
23, 2002, the disclosure of which is incorporated herein by
reference, are located at the corners of the shell and are
integrally molded therein, the lugs including openings therein for
receiving rods or other anchoring members. As mentioned above, the
shell preferably includes one, and most preferably two or more
manway openings integrally molded therein. The manway openings are
preferably circular and have a collar with a circumscribing trough
adjacent thereto. The trough is permitted to flex and deform under
vertical loading in use, and as a result, the collar is isolated
from much of the deformation which would otherwise occur. By the
use of such a circumscribing trough, the collar retains its shape
under a variety of loading conditions and thus the manway cover can
be coupled to the collar under such varying load conditions.
Moreover, the manway openings are recessed to a sufficient degree
to isolate not only the rims of the manways but also their covers
from extension above the upper wall of the shell and thereby reduce
deformation due to external forces or the contents of the tank. By
such a construction, the usual problems associated with synthetic
resin tanks designed for underground storage of liquids such as
water tanks, septic tanks and the like are large ameliorated.
[0016] Another feature of the tank of the present invention is the
inclusion of lifting lugs and adjacent, complementally located and
configured recesses. These lugs and recesses are preferably molded
into the
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of my new underground storage
and septic tank showing the shell having the stabilization lugs,
reinforcements, and the collar with the circumscribing troughs on
the manway openings, with the manway covers shown attached to the
shell and inlet and vent pipes shown in dashed lines;
[0018] FIG. 2 is a plan view of the underground storage and septic
tanks of FIG. 1, showing the circumscribing troughs around the
manway openings and the reinforcement mounts in the top of the
shell;
[0019] FIG. 3 is a side elevational view of the tank showing the
longitudinally and laterally spaced receiving pockets each with a
reinforcement mount and the covers mounted on the collars of the
manways;
[0020] FIG. 4 is a perspective view shown in vertical section along
line 4-4 of FIG. 2 to show the reinforcements in vertical
orientation between opposed reinforcement mounts;
[0021] FIG. 5 is a vertical cross-sectional view taken along line
5-5 of FIG. 3, showing the reinforcement members and the
reinforcement mounts in the chamber of the tank with the cover
removed;
[0022] FIG. 6 is an enlarged, fragmentary vertical sectional view
of one of the manways showing the trough and the collar;
[0023] FIG. 7 is an enlarged, bottom view of one of the covers for
the manway;
[0024] FIG. 8 is an enlarged, vertical sectional view taken along
line 8-8 of FIG. 7 through one of covers and showing the cover in
an inverted orientation;
[0025] FIG. 9 is a perspective view of a second embodiment of the
tank of the present invention wherein the receiving pockets are
provided with openings and the ends of the tank include a
castellated extension for receiving inlet and vent piping, shown in
dashed lines;
[0026] FIG. 10 is a top plan view of the tank of FIG. 9 with one of
the covers attached to a manway and the other manway having the
cover removed;
[0027] FIG. 11, is a side elevational view of the tank of FIG.
9;
[0028] FIG. 12 is a vertical cross-sectional view taken along line
12-12 of FIG. 11, showing the molded-in tubular members extending
vertically between openings in the receiving pockets as having a
frustoconical shape;
[0029] FIG. 13 is a vertical cross-sectional view taken along line
12-12 of FIG. 11 showing an alternate configuration of the
molded-in tubular members as tapered to a waist which is narrowed
relative to cross-sectional areas of the openings;
[0030] FIG. 14 is a side elevational view of two of the tanks of
FIG. 9 in stacked, top-to-top relationship, with portions of the
upper wall of each tank broken away to show the lifting lugs of
each tank are nested into recesses of the other tank stacked
therewith;
[0031] FIG. 15 is a perspective view of a third embodiment of the
tank of the present invention, wherein the receiving pockets have a
substantially flat, imperforate base wall;
[0032] FIG. 16 is a vertical cross-sectional view taken transverse
to the longitudinal axis of the tank of FIG. 15 and similar to the
view shown in FIG. 12, showing the chamber within the tank;
[0033] FIG. 17 is a side elevational view of a further embodiment
of the tank of the present invention, showing the receiving pockets
extending in a vertical direction such that the vertically aligned
receiving pockets meet to provide mutual support, the opposite side
being substantially a mirror image; and
[0034] FIG. 18 is a vertical cross-sectional view taken along line
18-18 of FIG. 17, showing the interconnection of the base walls of
the receiving pockets substantially midway along the side walls of
the shell.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0035] Referring now to the drawings, a underground storage and
septic tank 10 may be used for receiving, storing and discharging
liquids such as water or a combination of liquids and solids such
as sewage. The tank 10 broadly includes a shell 12 and at least
one, and preferably a plurality of covers 14 removably mounted on
the shell 12. The shell 12 encloses a chamber 16. The shell 12 and
the covers 14 are preferably rotationally molded of a synthetic
resin such as high density polyethylene (HDPE), and is of unitary
construction. The covers 12, and the details of the manways on
which they are mounted, are shown in FIGS. 7 and 8 and are common
to each of the embodiments described herein. As used in this
application, the terms "upright", "vertical", and "horizontal" are
used for ease of reference in regard to the position of the tank 10
in normal operation.
[0036] In the tank 10 shown in FIGS. 1-6, at least one, and
preferably a plurality of reinforcements 18 are mounted in upright
orientation within the chamber 16. The shell 12 is unitary and
molded as a single unit. The shell 12 includes at least one, and
preferably a plurality of manways 20, an outer wall 22,
reinforcement mounts 24, and stabilization lugs 26. The outer wall
22 of the shell 12 is preferably configured along a longitudinal
axis which extends generally along line 4-4 of FIG. 2, and a
vertical plane extending upwardly through the longitudinal axis
substantially bisects the tank 10 lengthwise. The tank 10 is
elongated with generally dome-shaped ends 28 and 30. The manways 20
are provided along the upper wall 32 of the outer wall 22 when the
tank 10 is in use. Each of the manways includes an upright
cylindrical collar 34 surrounded by a trough 36 which is recessed
inwardly toward the chamber 16. The outer wall 22 also includes a
lower wall 37 having arcuate lateral edges and a substantially flat
bottom surface, and may have a side wall 39 which is substantially
flat in an upright direction and which partially wraps around the
dome-shaped ends.
[0037] The shell also includes a plurality of receiving pockets 38
each of which include a pair of opposing side walls 40 and 42, an
upright inboard wall 44 and a generally laterally extending base
wall 46, the reinforcement mounts 24 being integrally molded as a
part of the base wall 46. The receiving pockets 38 are arranged in
opposed pairs both vertically and laterally when the tank 10 is in
use. Thus, receiving pockets 38a and 38b, 38c and 38d, and 38e and
38f are laterally displaced relative to each other along the upper
side 32 of the outer wall 22, and receiving pockets 38g and 38h,
38i and 38j, and 38k and 38l are laterally displaced relative to
each other along the lower side 48 of the outer wall 22. In
addition, receiving pocket 38a is positioned in alignment above
receiving pocket 38g, receiving pocket 38b is positioned in
alignment above receiving pocket 38h, receiving pocket 38c is
positioned in alignment above receiving pocket 38i, receiving
pocket 38d is positioned in alignment above receiving pocket 38j,
receiving pocket 38e is positioned in alignment above receiving
pocket 38k, and receiving pocket 38f is positioned in alignment
above receiving pocket 38l. The vertical alignment of the receiving
pockets 38 permits the mounting of the reinforcements 18 on the
reinforcement mounts 24 between the base walls 46, and the
longitudinal and lateral spacing of the receiving pockets 38
provides additional strength to the shell 12 in addition to the
strength added by the reinforcements 18.
[0038] The base wall 46 of the receiving pockets is extends
substantially horizontally when the tank 10 is in its normal
position of use. The upright inboard wall 44 of the receiving
pockets may lie in a plane substantially parallel to a vertical
plane through the longitudinal axis of the tank 10, as is shown in
regard to pockets 38c, 38d, 38i and 38j, or lie in a plane which
intersects a vertical plane through the longitudinal axis as is
shown in regard to the upright inboard walls 44 of receiving
pockets 38a, 38b, 38e, 38f, 38g, 38h, 38k and 38l. Such an angled
orientation may be useful to provide greater support when the
pockets 38 are positioned with greater lateral spacing so that they
are located on the dome-shaped ends 28 and 30 as shown in the tank
10 of FIGS. 1-6. The receiving pockets may be grouped into sets for
ease of reference. Thus, a set of receiving pockets 38 may include
receiving pockets 38a, 38c and 38e along one side of the upper wall
of the tank, and another set 38g, 38i and 38k which are positioned
respectively beneath the pockets 38a,38c and 38e. Another grouping
maybe to consider the receiving pockets on one side of a upright
plane bisecting the tank in one set (e.g., receiving pockets 38a,
38c, 38e, 38g, 38i and 38k) and the receiving pockets on the other
side of the bisecting plane in another set (e.g., receiving pockets
38b, 38d, 38f, 38h, 38j and 38l). Further, the receiving pockets 38
can be grouped into pairs, such as superposed pairs 38a and 38g,
38b and 38h, etc.) or lateral pairs (e.g., 38a and 38b, 38c and
38d, 38g and 38h, etc.).
[0039] The upper wall 32 of the outer wall of the shell 12 is
generally arcuate when viewed along the longitudinal axis as seen
in FIG. 5, and includes an arcuate top surface 48 having arcuate
edges 50 and 52 from which an arcuate, upright shoulder wall 54
extends downwardly to the trough 36 of each of the manways 20. The
domed-shaped ends 28 and 30 also include margins 56 and 58
respectively, from which an arcuate, upright panel wall 60 extends
downwardly to the trough of each of the manways 20. The upright
shoulder wall 54 is longitudinally separated from and opposed to
the upright panel wall 60 for each of the manways 20, with
receiving pockets 38 separating them. The receiving pockets 38a and
38b communicate with one of the troughs 36 and receiving pockets
38e and 38f communicate with the other of the troughs 36. This not
only relieves stress on the manways 20 but also faciliates drainage
from the troughs 36 down into the receiving pockets 38 so that
water or other material collected into the troughs does not enter
the chamber through the manways when the covers are removed. The
receiving pockets 38 are all provided with radiused internal
corners to reduce stress concentrations and facilitate load
transfers through the receiving pockets to the outer wall.
[0040] The dome-shaped ends 28 and 30 each include an upright
recess 62 extending inwardly toward the chamber and having a flat
end-facing wall 63, and also present upright flat end walls 64. The
upright recesses 62 extend vertically the majority of the height of
the tank 10. The recesses 62 provide additional structural rigidity
to the shell 12 and enable an anchoring member to be received
therein to retard longitudinal or lateral movement of the tank 10.
Also, as shown in that application, the outer wall of the shell may
include a plurality of longitudinally spaced, circumferentially
oriented reinforcing ribs to provide additional strength to the
shell 12. The tanks 10 are also preferably provided with suitable
passages including fittings for receiving piping and provided with
gaskets or the like, preferably located in the recesses of the dome
shaped ends, by which liquid such as water or a combination of
liquids and solids as in sewage may be received and discharged, all
as shown in my co-pending U.S. application Ser. No. 10/055,440, the
disclosure of which is incorporated herein by reference. Thus, the
flat end-facing walls of the recesses 62 on the dome-shaped ends 28
and 30 are suitable for allowing the installer to make a hole into
the tank 10 for the mounting of vent piping 65 and inlet piping 67
for introducing liquid such as water or sewage into the chamber
16.
[0041] The stabilization lugs 26 are located in opposed pairs on
the dome-shaped ends 28 and 30 to be essentially positioned at
corners of the shell 12, each of the stabilization lugs 26 being
molded in hollow, substantially L-shaped configurations integrally
with the outer wall 22 to provide a hole 66 for the receipt of
rods, posts or other anchoring members through the hole 66. The
stabilization lugs 26 thus fluidically communicate with the chamber
16, and include a first arm 80 extending substantially horizontally
and substantially parallel to the longitudinal axis and a second
arm 82 extending substantially horizontally and substantially
perpendicular to the longitudinal axis.
[0042] The reinforcement mounts 24 are positioned in the receiving
pockets 38 and preferably configured with a flat, substantially
annular base 68 and a short cylindrical stub tube 70 extending from
the base 68 inwardly from the inner surface 71 of the pockets 38
into the chamber. Alternatively, the reinforcement mounts could be
molded as simple recesses or grooves along the inner surface 71 of
the base wall of the receiving pockets 38 to hold the
reinforcements in position. The stub tube 70 has an enclosed end 72
to maintain the chamber against leakage therethrough. The
reinforcements 18 are members, and preferably tubes, in the shape
of cylinders complemental to the configuration of the mounts 24 so
that the ends 74 and 76 of the reinforcements 18 are engaged
against the base 68 and held against lateral movement by the tubes
70 of the mounts. Because the end 72 of each mount 24 is enclosed,
the reinforcements 18 may be provided with perforations 73 to
permit the flow of liquid therein so that no substantial reduction
of the volume of the chamber is caused by the use of the
reinforcements 18 therein. It may be appreciated that the tubes
could be square or a variety of other shapes in cross section, and
that the base 68 could be enclosed if desired so that the
reinforcements 18 are received within the tubes 70 rather than
positioned with the tubes 70 extending into the reinforcements 18
as shown in the drawings. The receiving pockets 38 positioned on
opposite sides of the manways 20 receive water draining off of the
troughs 36 and the base wall of each receiving pocket 38 is
inclined downwardly from the inboard to the outboard to facilitate
further drainage.
[0043] The collars 34 of each of the manways 20 include recesses in
the rim 74 which receive complementally positioned and spaced
radially inwardly projecting lugs 78 on the covers 14 so that the
covers 14 (shown in FIGS. 7 and 8 detached from the tank 10) may be
pushed down and twisted into locking condition with the manways.
The manways 20 may also receive risers thereon which increases the
effective depth below grade in which the tanks 10 may be placed.
The tanks 10 are also preferably provided with suitable passages
including fittings for receiving piping and provided with gaskets
or the like, preferably located in the recesses of the dome shaped
ends, by which liquid such as water or a combination of liquids and
solids as in sewage may be received and discharged, all as shown in
my co-pending U.S. application Ser. No. 10/055,440, the disclosure
of which is incorporated herein by reference. Also, as shown in
that application, the outer wall of the shell may include a
plurality of longitudinally spaced, circumferentially oriented
reinforcing ribs to provide additional strength to the shell
12.
[0044] The shell 12 is preferably integrally molded of synthetic
resin, such as high density polyethylene by rotational molding. The
covers 14 are separately molded also preferably of a synthetic
resin such as high-density polyethylene and are double-walled,
having a space between the upper and lower wall layers which
provides both thermal insulation and greater resistance to
impact.
[0045] In the case of tank 10, the reinforcement mounts 24 are
molded into the shell. The reinforcements 18 may be of a variety of
materials but are preferably molded of a synthetic resin such as
high-density polyethylene or polyvinylchloride (PVC). After the
completion of the molding, the shell 12 is entered through the
manway 20 and the base walls 46 are pushed apart by a mechanical
jack or ram or by the strength of the installer so that the
reinforcements 18 may be positioned over the tubes of the
reinforcement mounts 24. Once the separating force applied between
the receiving pockets 38 is removed, the reinforcements 18 are
firmly positioned between the opposing mounts 24 and captured
thereon. In the embodiment illustrated in FIGS. 1-6, the
reinforcements 18 are in upright, substantially vertical
orientation, but the receiving pockets and their opposing mounts
could be formed so that the reinforcements 18 are lateral,
substantially horizontally oriented, or a combination of some
upright orientations and some laterally oriented. For example, if
some of the receiving mounts are formed in the upright inboard wall
44 of laterally spaced receiving pockets, e.g. receiving pockets
38a and 38b, then the reinforcements 18 could be positioned for
providing lateral reinforcement. Moreover, in the construction of
the tank 10 hereof, receiving mounts could be formed in both the
base walls 46 and the upright inboard walls 44 of the receiving
pockets, so that the reinforcements 18 could be mounted in both
vertical and horizontal orientations, providing yet further
strength and reinforcement to the shell 12 without substantially
affecting the capacity of the chamber.
[0046] A second embodiment of the tank 10A of the present invention
is shown in FIGS. 9 through 14, with like numbers used to represent
like features. With regard to the tank 10A, a plurality of ribs 90
are formed in the outer wall 22 to provide additional structural
rigidity in a circumferential direction. The ribs 90 are formed by
slots 92 extending inwardly toward the chamber 16, and include
upright slots 94 which are formed in the side walls 37 and extend
into the upper wall 32 and the lower wall 39, upper transverse
slots 96 extending across the upper wall 32, and lower transverse
slots 98 extending across the lower wall. As may be seen by FIG. 9,
some of the upright slots 94 extend between and communicate with
superposed pairs of the receiving pockets 38 to further promote
drainage and provide structural rigidity. In addition, at least one
of the upper transverse slots 96 extends between and communicates
with two laterally spaced receiving pockets, and as seen in FIG.
11, some of the lower transverse slots 98 extend across to
communicate with laterally opposed receiving pockets 38, while
others of the lower transverse slots 98 extend between the arcuate
portions of the lower wall longitudinally intermediate the
receiving pockets 38 on the lower wall.
[0047] The upper wall 32 is also provided with lifting lugs 100
extending upwardly from the top surface 42 which include a
transverse opening 102 to facilitate receipt of a hook or cable for
lifting the tank 10A. A recess 104 is formed in the upper wall 32
in side-by-side relationship immediately adjacent each of the
lifting lugs 100. The sizing and positioning of the recesses 104
and lifting lugs 100 is complementary, whereby two tanks 10A can be
stacked in top-to-top relationship as shown in FIG. 14, with the
lifting lugs 100 of one of the tanks 10A received in the recesses
of the other of the tanks 10A. This aids in positioning the tanks
10A for transport or storage and reduces incidents of damage to the
lifting lugs 100 during transport.
[0048] The dome shaped ends 28 and 30 of the tank 10A are slightly
modified to provide a castellated extension 106 on the flat
end-facing wall 63. The provision of this castellated extension at
each end facilitates the mounting of vents or inlet piping to the
tank 10A by raising the height where an opening can be placed, thus
allowing more liquid to be received into the tank 10A because the
vent and inlet can be positioned at a greater height and remain
above the level of the liquid in the tank 10A.
[0049] The receiving pockets 38 in tank 10A are modified such that
the upright inboard walls 44A are oriented to be substantially
parallel with an upright axis through the longitudinal axis of the
tank, which is located at the same position as line 4-4 of FIG. 2.
Further, the base walls 46A are provided with openings 108 therein.
The openings 108 in each of the base walls 46A are fluidically
connected by upright tubular members 110 integrally formed with the
shell 12 by kiss-offs in the rotational molds. The tubular members
110 are best seen in FIGS. 12 and 13, and are integrally molded
with the shell to prevent the escape of liquid from the tank 10A or
the intrusion of liquid or debris into the tank. The tubular
members 110 may be configured as tapered, frustoconically shaped
tubes 112 as shown in FIG. 12, which taper from a greater
cross-sectional area of the opening 108A in the upper receiving
pocket 38A of the superposed pair to the opening 108B in the lower
receiving pocket 38A' of the pair. Alternatively, the tubular
members may be configured with an hourglass shape having a waist
112 with a narrower cross-sectional area than either of the
openings in the upper receiving pocket or the lower receiving
pocket of the superposed pair as illustrated in FIG. 13. The
tubular members provide structural support within the tank 10A and
increase rigidity, and further a flow of some of the water or other
liquid which collects on the base walls 46A to drain through the
tubular members 110 rather than around the outside of the
walls.
[0050] FIGS. 15 and 16 show a third embodiment of the tank 10B.
Tank 10B is similar in all respects to tank 10A, with the exception
that no reinforcements are provided between the base walls 46B of
the receiving pockets 38B. The base walls 46B are substantially
smooth and are imperforate. In many applications, the reinforcement
pockets 38B will provide sufficient structural rigidity that no
internal reinforcements are needed. Also, the limited amount of
ribbing on the tanks 10, 10A and 10B allows relatively greater wall
thickness without the addition of resin during the molding process.
A typical wall thickness of a 1000 gallon tank having a thin wall
where substantially ribbing is required is about 1/4 inch, whereas
substantially the same amount of resin produces a wall thickness of
1/2 inch in a tank having little or no ribbing, such as the tanks
hereof. Thus, the tanks of the present invention which have little
or not ribbing utilize the receiving pockets 38 to gain structural
rigidity without the necessity of adding substantial additional
resin to increase wall thickness.
[0051] FIGS. 17 and 18 show a modified version of the tank 10C of
FIGS. 15 and 16, wherein the receiving pockets 38C have a greater
vertical extension than the receiving pockets of tanks 10, 10A and
10B. The receiving pockets 38C are imperforate and do not include
openings in their base walls 46C. The side walls 40C and 42C as
well as the upright inboard wall 44C have a greater vertical
extension, such that the depth of the pockets 38C is increased in a
direction transverse to the longitudinal axis of the tank 10C. The
base walls 46C of the receiving pockets 38C which are in
substantial vertical alignment meet at a junction 114 formed by a
kiss-off in the rotational molding process, such that the resin
forming the shell fuses together at the junction 114. The base
walls 46C form an inlet 116 outboard of the junction 114 as seen in
FIG. 18, but the inlet 116 does not fluidically communicate with
the chamber 16. The base walls 46C also form a cove 118 inboard of
the junction 114 which fluidically communicates with the chamber
16. The inlets 116 and the coves 118 lie outboard of the vertical
plane passing through the longitudinal axis of the tank 10C, which
is in the same location as illustrated by line 4-4 of FIG. 2. The
junction 114 extends longitudinally along the receiving pocket 38C
to connect to the side walls 40C and 42C and is positioned more
proximate the upright inboard wall 44C than the closest side wall
39 and thus allows the upright inboard walls 44C and the side walls
40C and 42C of the lower receiving pocket 38C of the pair of
receiving pockets to provide support to the upper receiving pocket
38C positioned thereabove.
[0052] In use, after a hole or pit is excavated in the ground for
receiving the tank 10 and suitable preparation such as a liner or
gravel or sand is poured into the excavated pit to provide a base,
the shell 12 is lowered into the pit. A sling may be used to lower
the shell 12, or alternatively cables with hooks or the like may be
connected to the lifting lugs or to the stabilization lugs at the
corners of the shell for lifting and lowering the shell 12 into
position. Added support and stability may be achieved by contouring
the pit to conform to the receiving pockets 38 in the upper wall 32
and/or lower wall 39. That is, the receiving pockets 38 provide
locations for anchoring the tank by resisting movement, and further
gain structural support not only in the shell 12 as designed, but
also by providing a location for the receipt of external support by
providing earth fill or adding masonry support into the receiving
pockets 38. Rods or stakes may be driven through the holes 66 and
into the ground in the pit for holding the shell in position, and
pipes may be connected to suitable fittings to deliver and
discharge liquid and/or liquids and solids into the shell 12 and
vents installed as shown in the dashed lines in FIGS. 1, 9 and 15.
As noted above, risers may be coupled to the manways 20 depending
on the depth of the upper side of the shell relative to the surface
of the soil surrounding the tank 10 as ultimately graded. Covers 14
are then mounted on the manways 20 or risers, and then the final
grading is performed and the tank 10 is ready for use.
[0053] The receiving pockets 38 are uniquely configured such that
their upright inboard walls 44 are at least about 15% and
preferably about 20% or more of the height of the shell 12, and the
base walls 46 are at least about 15% and preferably about 20% or
more of the width of the shell 12. The 90.degree. angle between the
upright inboard wall 44 and the base wall 46 acts like a gusset to
aid in transferring the loads from a horizontal to a vertical
direction and vice versa. By providing arcuate wall surfaces
adjacent and intermediate the receiving pockets, the receiving
pockets 38 not only give support to resist flattening or
"parallelogramming" of the tank 10 when external loads are placed
on the tank, but also serve to transfer loads in a vertical
direction to a horizontal direction so that the side fill in the
pit around the shell 12 yields additional support. Vertical loads
might be caused by a tractor or other vehicle driving over the
tank. Horizontal loads might be caused by ground heave, seismic
events or traffic on the surface not over but adjacent to the tank.
Thus, the receiving pockets 38 may transfer side loading through
the base wall 46 to the upright inboard wall 44 to more evenly
distribute external forces to the earth supporting the tank.
[0054] Another advantage of the present invention is that even
though external forces or weight of the contents of the tank may
cause minor deformations, such deformations are largely isolated
from the manway and the cover secured thereon. By the provision of
the trough surrounding the collar, the trough permits yielding of
the adjacent wall while limiting the transfer of deformation to the
collar. This is beneficial in allowing access to be gained to the
interior of tank notwithstanding a large passage of time during
which many external events may have occurred which would bind the
cover in other synthetic resin subterranean tanks.
[0055] Although preferred forms of the invention have been
described above, it is to be recognized that such disclosure is by
way of illustration only, and should not be utilized in a limiting
sense in interpreting the scope of the present invention. Obvious
modifications to the exemplary embodiments, as hereinabove set
forth, could be readily made by those skilled in the art without
departing from the spirit of the present invention. For example, as
noted above, the shell 12 may be provided with relatively thinner
walls by providing circumferentially extending transverse ribs in
the outer wall. Multiple passages with fittings may be provided for
additional pipes to deliver or discharge liquid. PVC T-pipes may be
provided internally of the tank, and the pipes may extend
downwardly to the bottom of the tank for connection to a pump for
pumping water or other liquid from the tank.
[0056] The inventor hereby states his intent to rely on the
Doctrine of Equivalents to determine and assess the reasonably fair
scope of his invention as pertains to any apparatus not materially
departing from but outside the literal scope of the invention as
set out in the following claims.
* * * * *