Title:
Leak resistant concrete septic tank
Kind Code:
A1


Abstract:
A method for constructing a leak resistant concrete septic tank and the associated tank is provided. In one embodiment, the method includes pouring an integral tub having an integral tub cap and an integral tub sidewall. The integral tub may have a base attachment surface. Following pouring, the integral tub is cured. Once cured, the integral tub may be oriented to position the base attachment surface over a gravity base form. A base may be created in the gravity base form. The base attachment surface may be positioned at an integral tub set height from a bottom surface of the gravity base form. The base has a base thickness and a base ledge. The tub set height may be less than the base thickness. When the base is poured, a joint may be formed between the integral tub and the base. The formation of the joint encloses an influent chamber.



Inventors:
Wheeler, Richard (Blue Creek, OH, US)
Application Number:
11/484512
Publication Date:
01/17/2008
Filing Date:
07/11/2006
Assignee:
Stacey Wheeler
Primary Class:
International Classes:
B65D88/76
View Patent Images:
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Primary Examiner:
HONG, JOHN C
Attorney, Agent or Firm:
Luper Neidenthal & Logan (Colombus, OH, US)
Claims:
I claim:

1. A method for constructing a leak resistant concrete septic tank (50), comprising: (A) creating an integral tub (100) by pouring concrete into a gravity tub form (30) such that the concrete first fills a sidewall form portion (34) of the gravity tub form (30) to create at least one integral tub sidewall (300) and then, with continued pouring, the concrete fills a top portion (32) of the gravity tub form (30) creating an integral tub cap (200), wherein, (i) the integral tub cap (200) has a cap interior surface (210) and a cap exterior surface (220), and (ii) the integral tub sidewall (300) has a sidewall interior surface (310), a sidewall exterior surface (320), and a base attachment surface (340), (B) curing the integral tub (100) until the integral tub (100) is sufficiently strong, (C) orienting the integral tub (100) within a gravity base form (40) such that the base attachment surface (340) is at an integral tub set height (350), wherein the tub set height (350) is measured from the base attachment surface (340) to a bottom surface (42) of the gravity base form (40), (D) creating a base (500) by pouring concrete into the gravity base form (40) such that the base (500) has a base interior surface (510), a base exterior surface (520), a base perimeter (530), a ledge (540), and a base thickness (550), wherein the tub set height (350) is less than the base thickness (550), whereby the concrete contacts the base attachment surface (340) and then, with continued pouring, the concrete proceeds up the sidewall interior surface (310) and the sidewall exterior surface (320) thereby forming a joint (600) between the base (500) and the integral tub (100) such that the sidewall interior surface (310), the cap interior surface (210), and the base interior surface (510) enclose an influent chamber (15); and (E) curing the base (500) such that the base (500) hardens around the base attachment surface (340) and a portion of the integral tub sidewall (300) such that the joint (600) substantially prevents a liquid influent (10) from leaking out of the influent chamber (15) through the joint (600) during operation of the leak resistant concrete septic tank (50).

2. The method for constructing a leak resistant concrete septic tank (50) of claim 1, further including the steps of: (i) creating an influent port (800) through the integral tub sidewall (300) such that the influent port (800) extends from the sidewall exterior surface (320) to the sidewall interior surface (310), and (ii) creating an effluent port (900) through the integral tub sidewall (300) such that the effluent port (900) extends from the sidewall exterior surface (320) to the sidewall interior surface (310).

3. The method for constructing a leak resistant concrete septic tank (50) of claim 2, further including the steps of: (i) installing an influent fitting (810) into the influent port (800), and (ii) installing an effluent fitting (910) into the effluent port (900), such that when the influent (10) flows into the influent chamber (15) though the influent fitting (810), the influent (10) is treated, and an effluent (20) flows out of the influent chamber (15) through the effluent fitting (910).

4. The method for constructing the leak resistant concrete septic tank (50) of claim 1, wherein during the step of creating the integral tub (100), the integral tub sidewall (300) further includes positioning a reinforcement member (360) substantially longitudinally within the integral tub sidewall (300) so that the reinforcement member (360) protrudes from the base attachment surface (340) an extension distance (362), such that during the step of creating the base (500), the reinforcement member (360) extends into the base (500).

5. The method for constructing the leak resistant concrete septic tank (50) of claim 4, wherein the extension distance (362) that is less than the integral tub set height (350).

6. The method for constructing the leak resistant concrete septic tank (50) of claim 4, wherein the extension distance (362) is substantially equal to the integral tub set height (350).

7. The method for constructing the leak resistant concrete septic tank (50) of claim 1, wherein the integral tub set height (350) is between approximately 10% and approximately 60% of the base thickness (550).

8. The method for constructing the leak resistant concrete septic tank (50) of claim 1, wherein the sidewall exterior surface (320) is formed with a plurality of gripping fixtures (322) such that the gripping fixtures (322) ease rotation of the integral tub (100).

9. The method for constructing the leak resistant concrete septic tank (50) of claim 8, wherein the gripping fixtures (322) are indentations (323).

10. The method for constructing the leak resistant concrete septic tank (50) of claim 1, wherein the ledge (540) has a ledge width (542) measured from the sidewall exterior surface (320) to the base perimeter (530), and the ledge width (542) is between approximately 1 inch and approximately 6 inches.

11. The method for constructing the leak resistant concrete septic tank (50) of claim 1, wherein during curing of the base (500), as the base (500) hardens, compressive stresses are formed in the sidewall interior surface (310) and tensile stresses are formed in the sidewall exterior surface (320).

12. A method for constructing a leak resistant concrete septic tank (50), comprising: (A) creating an integral tub (100) by pouring concrete into a gravity tub form (30) such that the concrete first fills a sidewall form portion (34) of the gravity tub form (30) to create at least one integral tub sidewall (300) and an integral partition wall (400) and then, with continued pouring, the concrete fills a top portion (32) of the gravity tub form (30) creating an integral tub cap (200), wherein, (i) the integral tub cap (200) has a cap interior surface (210) and a cap exterior surface (220), (ii) the integral tub sidewall (300) has a sidewall interior surface (310), a sidewall exterior surface (320), and a base attachment surface (340), and (iii) the integral partition wall (400) has a influent chamber surface (410) and an effluent chamber surface (420), (B) curing the integral tub (100) until the integral tub (100) is sufficiently strong, (C) orienting the integral tub (100) within a gravity base form (40) such that the base attachment surface (340) is at an integral tub set height (350), wherein the tub set height (350) is measured from the base attachment surface (340) to a bottom surface (42) of the gravity base form (40), (D) creating a base (500) by pouring concrete into the gravity base form (40) such that the base (500) has a base interior surface (510), a base exterior surface (520), a base perimeter (530), a ledge (540), and a base thickness (550), wherein the tub set height (350) is less than the base thickness (550), whereby the concrete contacts the base attachment surface (340) and then, with continued pouring, the concrete proceeds up the sidewall interior surface (310) and the sidewall exterior surface (320) thereby forming a joint (600) between the base (500) and the integral tub (100) such that the sidewall interior surface (310), the cap interior surface (210), and the base interior surface (510) enclose an influent chamber (15), and the sidewall interior surface (310), the cap interior surface (210), the base interior surface (510), and the effluent chamber surface (420) enclose an effluent chamber (25); and (E) curing the base (500) such that the base (500) hardens around the base attachment surface (340) and a portion of the integral tub sidewall (300) such that the joint (600) substantially prevents a liquid influent (10) from leaking out of the influent chamber (15) through the joint (600) and the joint (600) substantially prevents the influent (10) from leaking out of the effluent chamber (25) through the joint (600) during operation of the leak resistant concrete septic tank (50).

13. The method for constructing a leak resistant concrete septic tank (50) of claim 12, further including the steps of: (i) creating an influent port (800) through the integral tub sidewall (300) such that the influent port (800) extends from the sidewall exterior surface (320) to the sidewall interior surface (310), (ii) creating an effluent port (900) through the integral tub sidewall (300) such that the effluent port (900) extends from the sidewall exterior surface (320) to the sidewall interior surface (310), and (iii) creating a passageway (430) through the integral partition wall (400) such that the passageway (430) extends from the influent chamber surface (410) to the effluent chamber surface (420) whereby the influent chamber (15) is in fluid communication with the effluent chamber (25).

14. The method for constructing a leak resistant concrete septic tank (50) of claim 13, further including the steps of: (i) installing an influent fitting (810) into the influent port (800), and (ii) installing an effluent fitting (910) into the effluent port (900), such that when the influent (10) flows into the influent chamber (15) though the influent fitting (810), the influent (10) is treated, and then the influent (10) flows into the effluent chamber (25) through the passageway (430) for further treatment, thereby creating an effluent (20) which flows out of the effluent chamber (25) through the effluent fitting (910).

15. The method for constructing the leak resistant concrete septic tank (50) of claim 12, wherein during the step of creating the integral tub (100), the integral tub sidewall (300) further includes positioning a reinforcement member (360) substantially longitudinally within the integral tub sidewall (300) so that the reinforcement member (360) protrudes from the base attachment surface (340) an extension distance (362), and during the step of creating the base (500), the reinforcement member (360) extends into the base (500).

16. The method for constructing the leak resistant concrete septic tank (50) of claim 15, wherein the extension distance (362) that is less than the integral tub set height (350).

17. The method for constructing the leak resistant concrete septic tank (50) of claim 15, wherein the extension distance (362) is substantially equal to the integral tub set height (350).

18. The method for constructing the leak resistant concrete septic tank (50) of claim 12, wherein the integral tub set height (350) is between approximately 10% and approximately 60% of the base thickness (550).

19. The method for constructing the leak resistant concrete septic tank (50) of claim 12, wherein the sidewall exterior surface (320) is formed with a plurality of gripping fixtures (322) such that the gripping fixtures (322) ease rotation of the integral tub (300).

20. The method for constructing the leak resistant concrete septic tank (50) of claim 12, wherein the gripping fixtures (322) are indentations (323).

21. The method for constructing the leak resistant concrete septic tank (50) of claim 12, wherein the ledge (540) has a ledge width (542) measured from the sidewall exterior surface (320) to the base perimeter (530), and the ledge width (542) is between approximately 1 inch and approximately 6 inches.

22. A leak resistant concrete septic tank (50) comprising: an integral tub (100) formed with an integral tub cap (200) and at least one integral tub sidewall (300), wherein when the integral tub (100) is formed by pouring concrete into a gravity tub form (30) such that, (i) the integral tub sidewall (300) is formed by pouring concrete into a sidewall form portion (34) of the gravity tub form (30), with the integral tub sidewall (300) having a sidewall interior surface (310), a sidewall exterior surface (320), and a base attachment surface (340), and the integral tub sidewall (300) has a reinforcement member (360) protruding from the base attachment surface (340); and (ii) the integral tub cap (200) is formed by continuing to pour concrete into a top form portion (32) of the gravity tub form (30), with the integral tub cap (200) having a cap interior surface (210) and a cap exterior surface (220); a base (500) formed with a base interior surface (510), a base exterior surface (520), a base perimeter (530), a base ledge (540), and a base thickness (550), wherein the base ledge (540) has a ledge width (542) measured from the base perimeter (530) to the sidewall exterior surface (320) such that the ledge width (542) is between approximately 1 inch and approximately 6 inches; and a leak resistant joint (600) joining the integral tub sidewall (300) to the base (500), wherein the leak resistant joint (600) is formed between the base (500) and the integral tub (100) as the base attachment surface (340) of the integral tub (100) is positioned within a gravity base form (40) at an integral tub set height (350) above a bottom surface (42) of the gravity base form (40) such that when the base (500) is poured, the concrete contacts the base attachment surface (340) and, with continued pouring, the concrete proceeds up the sidewall interior surface (310) and the sidewall exterior surface (320), and wherein the integral tub set height (350) is between approximately 10% and 60% of the base thickness (550), and the reinforcement member (360) extends an extension distance (362) from the base attachment surface (340) to the end of the reinforcement member (360) and that is substantially equal to the integral tub set height (350).

Description:

TECHNICAL FIELD

The instant invention relates to concrete structures, and, more particularly, to a method for constructing a leak resistant septic tank by pouring an integral tub having an integral tub cap and an integral tub sidewall, followed by curing the integral tub and pouring a base around a portion of the integral tub sidewall such that a joint is formed between the base and the integral tub.

BACKGROUND OF THE INVENTION

In the United States, all new homes must be connected to a public or a private waste treatment system. One type of private waste treatment for treating human waste, more commonly called wastewater, is a septic tank connected to a subsurface soil absorption field. The septic tank is a container, usually installed underground, that accepts wastewater and initiates the waste treatment process. The subsurface soil absorption field is sometimes referred to as a leach bed or drain field. Like the septic tank, the drain field is installed underground. It is connected on the downstream side of the septic tank and distributes the treated wastewater within a large volume of soil. In turn, the soil completes the treatment of the sewage. Nearly all private waste treatment systems are septic tanks connected to drain fields. However, in a minority of situations, the septic tank may be connected to a seepage pit. Septic tanks are commonly used in rural areas, or where public sewage systems are not available. This is true for nonresidential buildings as well. Accordingly, there are millions of septic tank wastewater treatment systems in the United States.

In a residential setting utilizing a private wastewater treatment system, such as a septic tank and drain field, wastewater flows into the septic tank and resides in a chamber where the wastewater undergoes separation. Settling produces a floating layer of scum, a bottom layer of sludge, and an intermediate layer of liquid. Anaerobic activity decomposes and compacts some of the solid waste in the sludge layer. The scum layer consists of those materials that float and do not decompose or decompose very slowly. An effluent, consisting primarily of the intermediate liquids, flows out of the septic tank and into the drain field. As previously described, the drain field is designed to disperse the intermediate layer of liquid over a large area within the ground and permits the soil to complete the process of filtering contaminants from the water. Because the septic tank and drain field are generally passive systems, where flow is influenced only by gravity, design and installation of the system are critical.

Various factors are taken into account in the septic tank design. First, wastewater contains a plethora of bacteria and viruses that are known biohazards. Diseases such as dysentery, cholera, hepatitis, and others can be transmitted by untreated waste, particularly if the waste reaches a water supply. Therefore, to protect public health septic tanks cannot leak. As an added difficulty, since septic tanks, as well as drain fields, are subterranean, visual inspection of the conditions of the various parts is impossible without extensive excavation. Leaks in the septic tank are usually not apparent, unless the leak manifests itself visually at the soil surface, via an offensive odor, or biologically through ground water contamination. Once a leaking septic tank has been identified it has usually been leaking for a lengthy period of time.

To prevent leaks, the septic tank must resist fracture due to the unrelenting pressures exerted on its exterior by the soil and additional pressure created by other objects that travel on the surface above the septic tank position. The septic tank must also bar entry of any subsurface water. Another design requirement is to limit the quantity of sludge and scum that enters the drain field as they tend to plug the drain field, inhibiting the treatment system's overall performance. Finally, septic tanks must be designed to endure these environment and operational challenges for decades without repair.

Additionally, septic tanks are usually designed to treat relatively large quantities of wastewater per twenty-four hour period. In general, tank capacities measure upwards from 750 gallons. While a variety of materials meet these challenges, septic tanks are most economically and commonly constructed of concrete.

Concrete is a mixture of cement and aggregate. The types of cement and the mixing ratios of aggregate and cement developed for specific purposes are too numerous to list here. However, the cement in concrete undergoes hydration when exposed to water. The hydration reaction of the calcium aluminosilicates cause the concrete to harden by adhering and binding the aggregates into a single mass. Curing concrete involves providing the necessary environmental conditions for the concrete to hydrate and obtain its optimum properties, particularly its strength.

There remains an unfulfilled need for a method of constructing a leak resistant concrete septic tank which is cost effective to manufacture, yet is of a robust design capable of resisting continuous soil pressures while operating to contain wastewater for many years.

SUMMARY OF INVENTION

In its most general configuration, the present invention advances the state of the art with a variety of new capabilities and overcomes many of the shortcomings of prior devices in new and novel ways. In its most general sense, the present invention overcomes the shortcomings and limitations of the prior art in any of a number of generally effective configurations. The instant invention demonstrates such capabilities and overcomes many of the shortcomings of prior methods in new and novel ways.

The present invention is a method for constructing a leak resistant concrete septic tank, and the associated tank. In one embodiment of the instant invention, the method for constructing the leak resistant concrete septic tank may begin by first creating an integral tub by pouring concrete into a gravity tub form. The concrete first fills a sidewall form portion to create at least one integral tub sidewall. A precast component is positioned within the gravity tub form. With continued pouring, the concrete fills a top form portion encasing the precast component to create an integral tub cap. In an embodiment of the integral tub, the integral tub may be a monolith with the integral tub sidewall having a sidewall interior surface, a sidewall exterior surface, a sidewall perimeter, and a base attachment surface. The base attachment surface may connect the sidewall interior surface to the sidewall exterior surface at one end of the integral tub sidewall.

The integral tub cap has a cap interior surface, a cap exterior surface, and a cap perimeter. Once the integral tub is poured, the concrete should be allowed to harden until the integral tub is sufficiently strong to handle. The integral tub may be positioned within a gravity base form at an integral tub set height. The tub set height may be measured from the base attachment surface to a bottom surface of the gravity base form.

Once the integral tub is positioned at the integral tub set height, the base may be poured. The base has a base interior surface, a base exterior surface, a base perimeter, a ledge, and a base thickness. In one embodiment of the instant invention, the tub set height is less than the base thickness. While pouring the base, the concrete contacts the base attachment surface prior to the base being fully poured. In another embodiment, the ledge may have a ledge width that extends from the sidewall exterior surface to the base perimeter. The ledge width may help stabilize the septic tank while it is submerged.

Once the poured concrete base hardens around the base attachment surface and a portion of the integral tub sidewall, a joint is formed. As a result, the sidewall interior surface, the cap interior surface, and the base interior surface enclose an influent chamber. The joint substantially prevents a liquid influent from leaking out of the influent chamber through the joint during operation of the leak resistant concrete septic tank.

In another embodiment of the instant invention, the septic tank may be poured with the integral tub having an integral partition wall. The integral partition wall has an influent chamber surface and an effluent chamber surface. After the base is poured and the joint is formed, an influent and an effluent chamber are enclosed by the integral cap, integral sidewalls, and the base interior surface. A passageway may be cut or drilled through the integral partition wall, or the passageway may be formed in the integral partition wall. The passageway fluidly connects the influent chamber with the effluent chamber.

In another embodiment of the instant invention, the integral tub sidewall has at least one reinforcement member. The reinforcement member protrudes from the base attachment surface an extension distance. The reinforcement member extends into the base and may enhance the strength of the joint.

The system of the instant invention enables a significant advance in the state of the art. The instant invention is, in addition, widely applicable to a large number of applications. Variations, modifications, alternatives, and alterations of the various preferred embodiments may be used alone or in combination with one another, as will become more readily apparent to those with skill in the art with reference to the following detailed description of the preferred embodiments and the accompanying figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Without limiting the scope of the present invention as claimed below and referring now to the drawings and figures:

FIG. 1 is an isometric view of an embodiment of the gravity tub form, showing creation of the integral tub, not to scale;

FIG. 2 is a cross-sectional view of the embodiment of the gravity tub form taken along section line 2-2 of FIG. 1, showing the filling of the sidewall form portion of the gravity tub form, not to scale;

FIG. 3 is a cross-sectional view of the embodiment of the gravity tub form taken along section line 2-2 of FIG. 1, showing the filling of the top form portion of the gravity tub form, not to scale;

FIG. 4 is an isometric view of an embodiment of the integral tub, not to scale;

FIG. 5 is a cross-sectional view of the embodiment of the integral tub, taken along section line 5-5 of FIG. 4, not to scale;

FIG. 6 is an isometric view of an embodiment of the integral tub being positioned with respect to an embodiment of the gravity base form, not to scale;

FIG. 7 is an isometric view of an embodiment of the integral tub and the pouring of an embodiment of the base with the integral tub substantially in position, not to scale;

FIG. 8 is a cross-sectional view of the embodiment of the integral tub and base taken along section line 8-8 of FIG. 7, not to scale;

FIG. 9 is an isometric view of an embodiment of the leak resistant concrete septic tank, not to scale;

FIG. 10 is a cross-sectional view of the embodiment of the leak resistant concrete septic tank taken along section line 10-10 of FIG. 9, showing an exploded view of an embodiment of a joint, not to scale;

FIG. 11 is an isometric view of an embodiment of the integral tub having a partition wall, not to scale;

FIG. 12 is a cross-sectional view of the embodiment of the integral tub taken along section line 12-12 of FIG. 11, not to scale;

FIG. 13 is an isometric view of an embodiment of the leak resistant concrete septic tank having a partition wall and inspection ports, not to scale; and

FIG. 14 is a cross-sectional view the embodiment of the leak resistant concrete septic tank taken along section line 14-14 of FIG. 13, not to scale.

DETAILED DESCRIPTION OF THE INVENTION

The method of constructing a leak resistant concrete septic tank of the instant invention enables a significant advance in the state of the art. The preferred embodiments of the device accomplish this by new and novel arrangements of elements and methods that are configured in unique and novel ways and which demonstrate previously unavailable but preferred and desirable capabilities. The detailed description set forth below in connection with the drawings is intended merely as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and features may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention.

Referring now generally to FIGS. 1 through 14, the present invention is a method for constructing a leak resistant concrete septic tank (50) and the resulting leak resistant concrete septic tank (50). The method may generally be described as first, pouring an integral tub (100), then allowing the integral tub (100) time to harden, followed by positioning the integral tub (100) so that a base (500) may be poured in contact with the integral tub (100), and lastly, allowing the base (500) to harden thereby forming a joint (600) between a portion of the integral tub (100) and the base (500). Now these steps will be described in detail.

In one embodiment of the instant invention, the method for constructing the leak resistant concrete septic tank (50) may begin by first creating the integral tub (100) by pouring concrete into the gravity tub form (30), as seen in FIG. 1. The concrete first fills a sidewall form portion (34) of the gravity tub form (30) to create at least one integral tub sidewall (300), as seen in FIG. 2. With continued pouring, the concrete fills the gravity tub form (30) vertically. As seen in FIG. 3, the concrete fills a top portion (32) of the gravity tub form (30) creating an integral tub cap (200). In one embodiment of the instant invention, prior to pouring an integral tub cap (200), a precast component (260) is positioned within the gravity tub form (30). Thus, as the integral tub cap (200) is poured concrete encases a portion of the precast component (260) to form the integral tub cap (200). One skilled in the art would recognize that other methods and forms may be used to create the integral tub (100). Alternatively, the gravity tub form (30) may be oriented so that the top form portion (32) fills first followed by the sidewall form portion (34). In essence then, the orientation of the gravity tub form (30) and the filling of the form (30) may be opposite to that which was previously described.

As best seen in FIGS. 4 and 5, in an embodiment of the integral tub (100), the integral tub (100) may be a monolith with the integral tub sidewall (300) having a sidewall interior surface (310), a sidewall exterior surface (320), a sidewall perimeter (330), and a base attachment surface (340). While the integral tub sidewall (300) may have a substantially rectangular shape, as seen in FIG. 4, other shapes are possible. As those skilled in the art will observe and appreciate, and by way of example and not limitation, the integral tub (100) may be formed with an integral tub sidewall (300) having a cylindrical shape. In an embodiment of the integral tub (100) having a substantially rectangular shape, as seen in FIG. 4, the sidewall perimeter (330) is formed with a sidewall proximal edge (332), a sidewall distal edge (334), a sidewall sinistral edge (336), and a sidewall dextral edge (338).

The integral tub cap (200), as seen generally in FIG. 5, has a cap interior surface (210), a cap exterior surface (220), and a cap perimeter (230). In an embodiment of the integral tub cap (200), the integral tub cap (200) may have an influent inspection port (240) that extends from the cap interior surface (210) to the cap exterior surface (220). As seen in FIGS. 2 and 3, the embodiment of the integral tub cap (200) is poured around the precast component (260) thereby forming the influent inspection port (240). However, as those skilled in the art will observe and appreciate, the influent inspection port (240) may be cut into the integral tub cap (200) at some point following the pouring of the integral tub (100). In another embodiment of the instant invention, the influent inspection port (240) may encompass the entire cap perimeter (230). In the embodiment of the integral tub (100), as seen in FIGS. 6, 7, and 9, the cap perimeter (230) generally forms a similar shape as the sidewall perimeter (330). In this rectangular embodiment, the cap perimeter (230) has a cap proximal edge (232), a cap distal edge (234), a cap sinistral edge (236), and a cap dextral edge (238), as seen in FIG. 7. As one skilled in the art will recognize, the cap perimeter (230) may have a variety of shapes and those shapes may be independent of the sidewall perimeter (330).

Once the integral tub (100) is poured, the concrete is allowed to harden until the integral tub (100) is sufficiently strong such that the integral tub (100) will support its own weight and resists fracture. In an embodiment of the instant invention, as seen in FIGS. 1 through 5, the integral tub (100) is poured with the base attachment surface (340) oriented down, although one with skill in the art will recognize that this is not a requirement of the present invention. To proceed with the construction, the integral tub (100) may be oriented with the base attachment surface (340) over a gravity base form (40), as seen in FIG. 6. In another embodiment of the present invention, reorientation of the integral tub (100) is eased by forming a plurality of gripping fixtures (322), seen only in FIG. 13, on the sidewall exterior surface (320). By way of example, and not limitation, the gripping fixtures (322) may be a plurality of indentations (323). The indentations (323) may allow a mechanical fixture to be releasably attached to the integral tub (100) and thus permit the integral tub (100) to be more easily positioned. As one skilled in the art will observe and appreciate, and as previously mentioned, the gravity tub form (30) may be constructed such that the base attachment surface (340) is up. In this orientation the integral tub sidewall (300) would be poured last and, consequently, the integral tub cap (200) would be poured first. In addition, the precast component (260) may or may not be used depending on the economics of using the precast component (260) to form the influent inspection port (240).

In the embodiment of the instant invention, as seen in FIGS. 6, 7, and 8, the integral tub (100) may be positioned within the gravity base form (40) having a gravity base form perimeter (44) at an integral tub set height (350), as seen in FIG. 8. As seen in FIG. 7, the sidewall perimeter (330) may be encircled by the gravity base form perimeter (44). The tub set height (350), best seen in FIG. 8, is measured from the base attachment surface (340) to a bottom surface (42) of the gravity base form (40).

Once the integral tub (100) is positioned at the integral tub set height (350), the base (500) is poured. Concrete is poured into the gravity base form (40), as seen in FIGS. 7 and 8, thereby contacting the base attachment surface (340) and a portion of the integral tub sidewall (300). Once poured, the base (500) has a base interior surface (510), a base exterior surface (520), a base perimeter (530), a ledge (540), and a base thickness (550), as seen in FIG. 10. In one embodiment of the instant invention, as seen in FIG. 8, the tub set height (350) is less than the base thickness (550). By positioning the base attachment surface (340) at the tub set height (350), that is, the base attachment surface (340) is positioned at a height less than the base thickness (550), the concrete may contact the base attachment surface (340) before the base (500) is fully poured. After the concrete has contacted the base attachment surface (340), with continued pouring, the concrete may proceed up the sidewall interior surface (310) and the sidewall exterior surface (320). In another embodiment of the instant invention, the integral tub set height (350) is between approximately 10% and approximately 60% of the base thickness (550). This range has been found to be particularly effective for forming a leak resistant joint (600) for 750 to 10,000 gallon tanks.

In another embodiment, the ledge (540) has a ledge width (542), as seen in FIG. 10, measured from the sidewall exterior surface (320) to the base perimeter (530), of between approximately 1 inch and approximately 6 inches. The ledge (540) may help stabilize the septic tank (50) when it is submerged within the earth by providing a surface whereby ballast, such as soil or gravel, may be added. Since flow through the septic tank (50) is due to the force of gravity, keeping the septic tank (50) at the correct elevation and orientation is critical to the system's operation.

As seen in FIGS. 9 and 10, once the poured concrete base (500) sets and hardens around the base attachment surface (340) and a portion of the integral tub sidewall (300), the joint (600) between the integral tub (100) and the base (500) is formed. As a result, the sidewall interior surface (310), the cap interior surface (210), and the base interior surface (510) enclose an influent chamber (15). The joint (600) substantially prevents a liquid influent (10) from leaking out of the influent chamber (15) through the joint (600) during operation of the leak resistant concrete septic tank (50).

In another embodiment of the instant invention, as the base (500) hardens around the portion of the integral tub sidewall (300) compressive stresses may develop in the sidewall interior surface (310). Similarly, tensile stresses may also develop in the sidewall exterior surface (320). Both the tensile and compressive stresses may develop due to contraction of the base (500) as the concrete hardens thereby pulling the sidewall (300) inward. The resulting stresses may improve the strength of the joint (600) thus making the septic tank (50) less likely to develop leaks during operation. Any external pressures, such as that due to the soil, acting upon the integral tub sidewall (300) must overcome any surface stresses that develop due to contraction of the base, in addition to the inherent strength of the concrete, before the integral tub sidewall (300) will rupture.

As one skilled in the art will observe and appreciate, the base (500), like the integral tub (100), may have other shapes. In the embodiment of the instant invention where the base (500), as seen in FIG. 9, is rectangular, the base perimeter (530) has a base proximal edge (532), a base distal edge (534), a base dextral edge (536), and a base sinistral edge (538). The integral tub (100) may also be substantially rectangular, although it is not necessary that the integral tub (100) and the base (500) have similar shapes. By way of example and not limitation, the base (500) may be circular with the integral tub (100) being rectangular, and the opposite situation is also possible. That is, the integral tub (100) may be substantially cylindrical with the base (500) being substantially rectangular.

In another embodiment of the instant invention, as seen in FIGS. 11, 12, and 13, the septic tank (50) may be formed with the integral tub (100) having an integral partition wall (400). During the step for creating the integral tub (100), concrete is poured into the gravity tub form (30). The concrete first fills the sidewall form portion (34) and a partition wall form portion (36) of the gravity tub form (30) to create the integral tub sidewall (300) and the integral partition wall (400), respectively. The concrete then continues to fill the gravity tub form (30) vertically. The concrete finally fills the top form portion (32) of the gravity tub form (30) to create the integral tub cap (200). In one particular embodiment, precast components (260) are positioned within the top form portion (32) of the gravity tub form (30). When the top form portion (32) is filled with concrete, the concrete encases a portion of each precast component (260) to form the integral tub cap (200). As seen in FIGS. 12, 13, and 14, the integral partition wall (400) has an influent chamber surface (410) and an effluent chamber surface (420). After the base (500) is poured and the joint (600) is formed, the influent chamber (15) is enclosed by the sidewall interior surface (310), the cap interior surface (210), the influent chamber surface (410), and the base interior surface (510). In addition to the influent chamber (15), an effluent chamber (25) is enclosed by the cap interior surface (210), the sidewall interior surface (310), the effluent chamber surface (420), and the base interior surface (510). A passageway (430) is cut or drilled through, or, in another embodiment, may be formed in, the integral partition wall (400). The passageway (430) fluidly connects the influent chamber (15) with the effluent chamber (25). As seen in FIG. 14, the passageway (430) is created through the integral partition wall (400) such that the passageway (430) extends from the influent chamber surface (410) to the effluent chamber surface (420).

In another embodiment of the instant invention, as seen in FIG. 14, during the step of creating the integral tub (100), the integral tub sidewall (300) has a reinforcement member (360) that is positioned substantially longitudinally within the integral tub sidewall (300). As one skilled in the art will recognize, and by way of example and not limitation, the reinforcement member (360) may be rebar that is commonly used to enhance the concrete's strength. The rebar may be straight, as seen in FIG. 14, or bent in such a manner to prevent pullout. The reinforcement member (360) protrudes from the base attachment surface (340) an extension distance (362) as measured from the base attachment surface (340) to the exposed end of the reinforcement member (360). Consequently, during the step of creating the base (500), the reinforcement member (360) extends into the base (500). The reinforcement member (360) may enhance the strength of the joint (600) making the joint (600) resistant to fracture due to the continuous pressures exerted on the sidewall interior surface (310) by the sludge, liquid, scum, and gases within the septic tank (50) and by the soil and liquid pressures bearing against the sidewall exterior surface (320). In one embodiment of the instant invention, the extension distance (362) may be less than the integral tub set height (350). In another embodiment of the instant invention, as seen in FIG. 14, the extension distance (362) is substantially equal to the integral tub set height (350). Therefore, when the integral tub (100) is positioned within the gravity base form (40), the reinforcement member (360) supports the integral tub (100) at the integral tub set height (350). When the base (500) is poured, the concrete encases that portion of the reinforcement member (360) that extends from the base attachment surface (340).

In another embodiment of the instant invention, as seen in FIGS. 9 and 10, the leak resistant concrete septic tank (50) has an influent port (800) extending from the sidewall exterior surface (320) to the sidewall interior surface (310), and an effluent port (900) extending from the sidewall exterior surface (320) to the sidewall interior surface (310). The ports (800, 900) may be cut or drilled through the sidewall surfaces (310, 320) following hardening of the integral tub (100) or following hardening of the base (500), or the ports (800, 900) may be formed during pouring of the integral tub sidewall (300). In another embodiment of the instant invention, as seen in FIGS. 13 and 14, an influent fitting (810) may be installed into the influent port (800), and an effluent fitting (910) may be installed into the effluent port (900). The fittings (810, 910) may provide connectivity to the upstream wastewater source and to the downstream treatment systems. Therefore, when the septic tank (50) is connected to a waste source, the influent (10) flows through the influent fitting (810) into the influent chamber (15) where initial treatment begins. The influent (10) then eventually flows into the effluent chamber (25) where treatment continues. Finally, with continued flow of additional influent (10) into the influent chamber (15), an effluent (20) flows out of the effluent chamber (25) through the effluent fitting (910) to a drain field or other downstream sewage treatment system.

In the embodiment of the instant invention seen in FIGS. 11 through 14, where the septic tank (50) is formed with the influent and effluent chambers (15, 25), labeled in FIG. 14 only, each chamber (15, 25) may have an inspection port (240, 250) for inspecting the ports (800, 900) or for inspecting the fittings (810, 910) or for determining the level of the scum, liquid, and sludge in each chamber (15, 25). As one skilled in the art will appreciate, the inspection ports (240, 250) also provide openings in the septic tank (50) enabling the septic tank (50) to be periodically emptied. While the inspection ports (240, 250) are shown as cylindrical extensions of the integral cap (200), as one skilled in the art will observe and appreciate, the inspection ports (240, 250) may be flush with the cap exterior surface (210) and may have a variety of other shapes. In another embodiment of the instant invention, the inspection ports (240, 250) are covered with removable lids (700), as seen in FIGS. 13 and 14. The lids (700) keep debris out of the septic tank (50) while simultaneously trapping the decomposition gases within the septic tank (50).

Numerous alterations, modifications, and variations of the preferred embodiments disclosed herein will be apparent to those skilled in the art and they are all anticipated and contemplated to be within the spirit and scope of the instant invention. For example, although specific embodiments have been described in detail, those with skill in the art will understand that the preceding embodiments and variations can be modified to incorporate various types of substitute and or additional or alternative materials, relative arrangement of elements, and dimensional configurations. Accordingly, even though only few variations of the present invention are described herein, it is to be understood that the practice of such additional modifications and variations and the equivalents thereof, are within the spirit and scope of the invention as defined in the following claims. The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or acts for performing the functions in combination with other claimed elements as specifically claimed.