The present invention is a foundational cistern. The present invention is an evolutionary panelized foundation system that uses known pre-casting technologies, functions structurally in similar ways to traditional systems, yet provides building designers with a multitude of new benefits in combination with the objectives of reduced construction time, energy, and water conservation. Stored rainwater in the cistern provides thermal mass for heating for a supported structure, and may be used for nonpotable uses. Given appropriate on-site water treatment, potable uses of stored rainwater may be contemplated as well. The foundational cistern of the present invention may be coupled to other foundational cisterns and structural elements of the supported structure. The present invention offers a multitude of advantages not currently known in the art of foundation products.

This application claims the benefit of U.S. Provisional Application No. 61/054,179 filed May 19, 2008. 
    
    
     BACKGROUND 
     Buildings consume roughly 36% of America's energy production and 12% of its potable water. Innovative building foundation designs are needed to significantly reduce this profile if we are to meet forthcoming water conservation and carbon dioxide emission standards. Use of pre-cast concrete for the construction of building foundations has been underway for over fifteen years, thereby establishing a precedent for use of off-site fabricated concrete panels used primarily for residential basement construction. At the same time, increased awareness about the environment has brought water conservation to the forefront, resulting in consumers who desire to create buildings that are ecologically sensitive, efficient, and economical. Cisterns have been used for many years as a means of containing rainwater and other liquids for long-term storage needs. 
     There is a need for innovation in the field of foundation design that addresses significant reduction in time required to construct building foundations, reduction of energy consumption, and enhanced water conservation. Presently no apparatus accounts for and addresses all of these combined concerns. 
     SUMMARY OF THE INVENTION 
     The present invention is a foundational cistern. The present invention is an evolutionary panelized foundation system that uses known pre-casting technologies, functions structurally in similar ways to traditional systems, yet provides building designers with a multitude of new benefits in combination with the above objectives of reduced construction time, energy, and water conservation. The present invention utilizes specific combinations of pre-cast septic tank based design and pre-cast wall systems, resulting in a foundation system that forms sealed crawl spaces, virtually eliminates the need for ducted air transfer through the application of open air plenum technology, and stores large amounts of rainwater collected from the roof of the structure. The current design of the present invention will provide approximately 7,000 gallons of stored water per approximately 1,000 square feet of single story dwellings, and approximately 3,500 gallons for two story buildings, or structures of similar area. The stored rainwater in the cistern provides thermal mass for heating the structure, and may be used for nonpotable uses such as irrigation, gardening, cleaning outdoor items, and the like. Moreover, it is contemplated that through the use of appropriate on-site water treatment, potable uses for stored rainwater in the foundational cistern is feasible. The present invention offers a multitude of advantages not currently known in the art of foundation products. 
     In one aspect, the present invention offers a significant reduction of energy consumption needed to heat buildings by moderating insulated sealed crawl space temperature variations. The present invention is compatible with earth sheltering finished grade designs, which augment steady state temperatures within the present invention's sealed crawl space design. The foundational cistern of the present invention augments controlled building mass thermal inputs by harvesting steady state temperature variations within soils averaging 55 degrees Fahrenheit beneath buildings. When properly used, this produces lowered heating loads for occupied space immediately above such foundations. 
     In one aspect, the present invention may be designed for construction of insulated sealed crawl spaces thereby saving heating operational utility expenditures for the life of the structure. 
     In another aspect, foundation cistern of the present invention also results in a reduction of detailed site excavation and building foundation construction time by about a factor of 10 (estimated installation time is one to two days in lieu of up to a range of ten to twenty days), thereby potentially lowering equivalent building foundation construction labor costs by up to 20% and minimizing exposure to weather related construction delays. 
     In yet another aspect, present invention also provides a complete structural foundation system for one or two story residential and light commercial buildings of up to two stories, having brick or stone veneer and which can bear normal roof loads having spans of up to approximately 40 feet under certain circumstances (e.g., type IV and V building loads in accordance with international, State of North Carolina, and local building code requirements). 
     In one aspect, the foundation cistern of the present invention provides low cost rainwater storage which can be recycled for on-site “non-potable” uses such as landscape irrigation, storm water mitigation, as well as serve as an earth coupled thermal transfer medium for heating and indirect cooling of inhabited areas. As stated above, with treatment, water may be potable. The present invention provides sealed storage of collected rainwater beneath the exterior building perimeter. Increased exposure to water vapor is avoided through the incorporation of separate air vent connections for each cistern. In contrast, prefabricated water containment systems are placed outside of building foundation perimeters costing about $0.50 more per stored gallon. The present invention avoids such costs because no further excavation is needed other than those normally associated with conventional foundation construction. 
     In another aspect, foundational cistern of the present invention eliminates use of poured-in-place concrete and masonry construction. This allows for the elimination of separate poured-in-place footings along with their specialized excavations, as well as time consuming, labor intensive, hand laid concrete block (CMU) typically used for continuous foundation perimeter walls. 
     In another aspect, the present invention provides an ideal extraction medium for the control and elimination of radon gas through use of a continuous gravel foundation medium. 
     In one aspect, the present invention is compatible with open plenum air distribution without exposure to high humidity normally associated with conventional practice (when properly installed and maintained). 
     In yet another aspect, the present invention may be designed for use in conjunction with either spray applied or rigid insulation board products intended for installation around the panelized building foundation perimeter. 
     In one aspect, the present invention may be sized to be compatible with either panelized or modular building components, which typically involve significantly less “embodied energy” relative to conventionally framed building construction. 
     In another aspect, the foundational cistern of the present invention may utilize local and readily available pre-cast septic tank industry resources, which are presently available throughout all United States jurisdictions. 
     In yet another aspect, the present invention addresses LEED (Leadership in Energy and Environmental Design) certification credits 556.1; 556.2; WE 3.1; and WE 3.2. 
     These and other benefits can be utilized by existing structures through a combination of retrofitted building load bearing pre-cast concrete cisterns, new building pre-cast concrete cisterns, and building load bearing pre-cast concrete walls. Given complete structural interface of these products, foundation building systems for both new buildings and building additions using the present invention is feasible and capable of providing builders, architects, and structural engineers with an alternative means of transferring building loads to bearing soil while taking advantage of the benefits indicated above. 
     Such advantages attained through the use of the foundation cistern of the present invention are vast. There are some circumstances where the present invention would not be applicable, such as: locations not exposed to rainfall, some structures requiring full height basement construction throughout their foundation perimeters, construction sites having soils types or inappropriate excavation characteristics or bearing building loads, and commercial buildings producing static and live loads in excess of approximately 2,700 pounds per lineal foot of foundation wall perimeter. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following drawings, description and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the accompanying advantages of this invention will become more readily appreciated as the same becomes understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1   a  is an isometric drawing showing an array of foundational cisterns forming a sealed, insulated crawl space. 
         FIG. 1   b  is an isometric rendering demonstrating the relationship between wood framed floor and walls with the foundational cistern unit of the present invention, according to one embodiment. 
         FIG. 2   a  is an illustration of the underside (typical) of an optional top cover unit configuration, identifying load bearing concrete positions of the foundational cistern of the present invention, according to one embodiment. 
         FIG. 2   b  is an illustration of the underside of an alternative top cover unit configuration, identifying load bearing concrete positions of the foundational cistern of the present invention, according to one embodiment. 
         FIG. 2   c  is an illustration of yet another underside top cover unit configuration, identifying load bearing concrete positions of the foundational cistern of the present invention, according to one embodiment. 
         FIG. 2   d  is an illustration of still an additional underside top cover unit configuration, identifying load bearing concrete positions of the foundational cistern of the present invention, according to one embodiment. 
         FIG. 3  is an illustration of a vertical cross-section of the foundational cistern, detailing elements and environment of use, according to one embodiment. 
         FIG. 4  is a depiction of a horizontal cross-section of the present invention demonstrating thickened corner, columns, pilaster column, web stiffener, and access hatch opening, in one embodiment. 
         FIG. 5   a  is a vertical section view at a pre-cast wall panel illustrating connection of the top cover of the present invention to an adjacent pre-cast concrete wall panel, according to one embodiment. 
         FIG. 5   b  is a plan section view of the connection of the top cover of the present invention to base unit, and connection to a pre-cast wall panel, in one embodiment of the present invention. 
         FIG. 5   c  illustrates, in a vertical section view, the detail of the connection between the top cover of the present invention and a pre-cast concrete wall panel, as in one embodiment. 
         FIG. 5   d  is a horizontal section illustration of a typical bolt connection between the base unit and a pre-cast concrete wall panel, as in one embodiment of the present invention. 
         FIG. 5   e  is a rendering of a horizontal section view of a connection between the base unit and a pre-cast concrete wall panel, as in one embodiment. 
         FIG. 6   a  is a horizontal plan section illustrating an alternative connection between a foundational cistern and a precast concrete wall segment, as in one embodiment. 
         FIG. 6   b  is a horizontal plan section demonstrating the interior section view of an alternative connection between two adjacent foundation cisterns, as in one embodiment. 
         FIG. 6   c  is an elevation view showing a welded connection between two adjacent foundation cisterns, as in one embodiment. 
         FIG. 7  is a vertical section rendering of the top cover primary load bearing lintel section and base unit of the present invention, in cross section, as in one embodiment. 
         FIG. 8  is a vertical section illustration of the non-primary load bearing top cover turn down edge with a knock out hole and the keyway at base unit of the present invention, as in one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is the best currently contemplated modes for carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention. 
     The principal purpose of the present invention, in one embodiment, is to utilize custom designed pre-cast concrete rainwater and non-potable water containment structures as adjunct building foundation components capable of supporting design loads of up to approximately 2,700 pounds per lineal foot at a building's perimeter load bearing locations. 
     The foundational cistern of the present invention is composed of four vertical walls ( FIG. 1 ), which are attached to a floor section, forming the base unit  118 . The four vertical walls may take on many dimensions and may form a variety of shapes. It is further contemplated that vertical wall reinforcement may be added or deleted to serve the needs of the building. In the preferred embodiment, four vertical walls are used. In this embodiment the two longer walls, that are opposite and parallel to one another, measure approximately 13 feet and 4 inches in width and 4 feet in height. The two shorter walls, that are positioned opposite and parallel to one another, in this preferred embodiment, measure approximately 5 feet 4 inches in width and 4 feet in height. 
     The floor section of the base unit  118 , measures approximately 13 feet and 4 inches by 5 feet and 4 inches, in this preferred embodiment. The floor section of each foundation cistern, in one embodiment, would be thickened to approximately 6″ in depth at specific locations whereby it would be possible to cast deformed reinforcing bars into the corner intersection formed by the floor of the tank and adjacent vertical walls. The reinforcing in this embodiment would allow the floor of the tank to react to the loads being transferred from the walls and lateral forces from the building structure above. The flat floor of the foundation cistern  158 , in this embodiment, would then be seen as a foundation footing replacement in compliance and exceeding minimum code requirements of 16″ wide×6″ depth plain concrete footings. Moreover the remaining portion of the base is sloped  157  to augment evacuation of stored rainwater in the foundational cistern, as is further illustrated in  FIG. 3 , and described below. 
     One of the vertical walls contains an opening  102  that can be accessed by an average-sized person, and may serve as a maintenance hatchway. In the preferred embodiment, the access opening  102  is circular in shape, although other shapes may be implemented and contemplated, as would be known by one skilled in the art. The access opening  102  may be covered by a hinged or bolted door  116  having a gasket or “o” ring, thus preventing the egress of material contained within the foundational cistern. A hinged or bolted door  116  may be water tight, as in the preferred embodiment of the invention. In the preferred embodiment, the access opening  102  measures not more than approximately 24 inches in diameter. 
     In the interior of the base unit  118  of the foundational cistern, there is a concrete stiffener  104 . The concrete stiffener  104  adds resistance to bending of the longer foundational cistern vertical walls when supporting loads by the building above. In a preferred embodiment of the present invention, the concrete stiffener  104  measures approximately 4 feet and 10 inches in width and approximately 1 foot and 10 inches in height, and its position ranges between approximately 1 foot 8 inches to 1 foot 10 inches above the floor section of the base unit  118 . Additionally, knock out holes  129  may be present to accommodate overflow of liquid to prevent the foundational cistern from filling completely with fluid, as in the preferred embodiment. The structural integrity and rigidity of the present invention is further supported by reinforcing bars  120  running vertically through the four corners and middle of the wall opposite the wall containing the access opening  102 . Reinforcing bars  120  also run horizontally through the foundational cistern base unit  118  floor  158 . The pilaster column  115  allows the present invention to tolerate the loads imposed by the structure the foundational cistern is supporting. Either a bolted or weld plate connection  117  is present in both the top and the lower outer edge of the base unit  118  and top cover  101  unit that facilitates the connection of the foundational cistern to other foundational cisterns, pre-cast wall panels, or similar material, as in one embodiment of the invention.  FIG. 1   a  illustrates the foundational cistern and its attachment to a pre-cast wall panel  119  and the pre-cast wall panel's  119  relationship to other structural elements of the building, a continuation of the pre-cast concrete panel  114  and rigid insulation  108 . Other aspects and elements of the base unit  118  will be described below. 
     The base unit  118  of the foundational cistern sits on a specified gravel base  106  (see  FIG. 3 ). The specified gravel base  106  sits on the compacted or undisturbed bearing soil  105 . Perforated pipe  147  is used to prevent lateral transfer of ground water beneath the foundational cistern assembly. The foundational cistern may be connected to a pre-cast wall panel  119  by a bolt or welded anchor connection  117 . In  FIG. 1   b  a view of this connection is illustrated. More detailed views are shown in  FIGS. 5   a - 5   e  and are described in more detail below.  FIG. 1   b  illustrates the base unit of the cistern where the base unit  118  is connected to a pre-cast wall panel  119 . 
     The top cover  101  of the present invention is placed on top of the base unit  118  for the foundational cistern to be operable. Thus, the top cover  101  is of a similar shape and plan area size as the base unit  118  in the final product. The top cover  101  may also be equipped with knock out holes  129  to allow the egress of excess fluid within the cistern and to accommodate transfer of stored water to nearby foundational cisterns, when present as in one embodiment. Additionally, a vent to the roof  103  is present, as in one embodiment, to allow the escape of air being pressurized or depressurized due to level changes in the water, as well as to vent water vapor from the cistern. Each of the four side edges of the top cover  101  contain reinforcing bars  120  to add strength to the cover. As shown in  FIGS. 2   a - 2   d , the edges of the top cover  101  are thickened and contain elements to withstand loads imposed by the building. Connection of the top cover  101  to the base unit  118  is further illustrated in  FIGS. 3 ,  7  and  8  and is described below. 
     When in use, the top cover  101  is connected to pre-cast wall paneling  119  or rigid insulation  108  as in one embodiment of the invention. A sole plate  130  (approximately two by six, in one preferred embodiment of the invention) is placed beneath the top cover  101  and positioned by the presence of shaped keyways  146 , as in one embodiment of the invention (see  FIGS. 3 and 7 ). The sole plate  130  then connects to the subflooring  155 , and furring strips  143  of the structure (see  FIGS. 1   b  and  3 ). Above the top cover  101  the wall framing of the structure is placed in alignment with the sole plate  130 . The top cover  101  is attached to the sole plate  130  by an anchor bolt  121  (further described below). Two by four (or two by two, as in another embodiment) furring strips  143  are placed on the top cover  101 , and radient heat distribution openings  112  are provided at the edges of those furring strips  143  that facilitate heating or cooling air flow from the foundational cistern to the building. Moreover, top mounted flange  156  are present in the flooring, as are floor joists  144  and a treated horizontal ledger  109  as illustrated in  FIG. 1   b.    
       FIGS. 2   a - 2   d  are illustrations of the underside portion of the top cover  101  of the foundational cistern, focusing on the turn down and lintel edges  122  of the top cover  101 . Anchor bolt  121  connections are depicted and illustrate potential locations where the top cover  101  may be attached to the subflooring  155 .  FIGS. 2   a - 2   d  show multiple turn down edges, locations  122  and  113 , and at load bearing walls. In the preferred embodiment, the primary load bearing turn down lintels  122  are 8 inches by 8 inches having 64 square inches of 5,000 psi concrete cross sectional area at all reinforced concrete lintel locations. Lintels and turn down edges are also depicted in  FIG. 3 . Note that turn down edges  113  may be present on any vertical wall of the top cover  101 .  FIG. 2   a  shows turn down lintels  122  on three sides of the top cover  101  where primary structural building loads are anticipated, as in one embodiment. It is contemplated and useful to include non-structural turn down edges  163  on only one side ( FIG. 2   c ), two sides ( FIGS. 2   b  and  2   d ), or three sides ( FIG. 2   a ). Moreover, monolithic turn down lintels  122  are only utilized where either continuous or point primary load reactions are anticipated from the building being supported by the foundational cistern, as is consistent with one embodiment of the invention. The top cover  101  rests on top of the base unit  118 , and is sealed thereon by way of a keyway seal at the joint  146 . This element is further described in  FIGS. 7 and 8 . 
       FIG. 3  further illustrates detailing of the present invention. For instance, as in one embodiment of the invention, a treated horizontal ledger  109  (2 by 4) is in contact with the top cover  101 . Other elements of the subflooring  155 ,  143 ,  144 , and  156  are described above and further illustrated in  FIG. 3 . The relationship of the anchor bolt  121  to the subflooring above the top cover  101  is also illustrated in  FIG. 3 . The slope  157  of the bottom floor of the base unit  118  is also shown. The 8 by 8 lintels  122  that provide load-bearing support to the structure above are also depicted. The keyway seal at joint  146  between the top cover  101  and base unit  118  is also shown, as is the access opening  102 . Reinforcing dowels  124  that provide structural rigidity to the present invention are also shown. Knock out holes  129  that may be opened to admit rain water or to prevent the cistern from filling entirely with liquid are shown in a variety of positions. As would be known by one skilled in the art, there may be only one, or a multitude of knock out holes  129  that be present in a plurality of positions. 
     The environment surrounding the foundational cistern is also shown in  FIG. 3 . Earth backfill  100  is used to stabilize and insulate the present invention, as is practiced in one embodiment. In one preferred embodiment, earth backfill  100  is present up to 4 feet in height at the exterior sides of the base unit  118  and wall panels  119 . Transference of loads from the bottom of the foundation cistern tanks of the present invention to bearing soils would be negotiated by use of approximately 4″ thick gravel base  106  placed on undisturbed grade or compacted select fill in one embodiment. The gravel medium  106  would be drained via use of industry standard 4″ diameter perforated plastic pipe  147  to daylight or gravel sump as is known in the art. Some soil types would require further consideration, yet still employ the present invention. The other side of the foundational cistern, in this preferred embodiment is the sealed crawlspace  107 . 
       FIG. 4  shows a horizontal cross-section of the present invention. This view provides added understanding to elements like the pilaster column  115  that provides added structural support to the mid-section of the present invention. Reinforcing bars  120  are shown in the four corners and mid section of the foundational cistern, as in one embodiment of the invention. Also shown, are the thickened corners  125  of the present invention, which provide depth of concrete for connections, and vertical transfer of building loads from above. Monolithic turn down lintels  122  described in  FIGS. 2   a - 2   d  are also identified in  FIG. 4 . The concrete stiffener  104  is in contact, on both sides, with reinforcing dowels  124 , which provides added structural support to the mid-section of the foundational cistern. The access hatch opening  102  and vertical door assembly  116  are also shown. 
       FIG. 5   a  is a vertical section view at a pre-cast concrete wall panel  119 . The top cover  101  of the foundational cistern is connected to the subflooring above through the use of an anchor bolt  121  that connects the top cover  101  to an offset sole plate  130 , as in one preferred embodiment of the invention. As demonstrated the sole plate  130 , and pre-cast wall panel  119  are in connection with the rigid insulation  108  of the building. Other means of fastening concrete to subflooring are known and may be contemplated by one of ordinary skill in the art. A nut and washer  127  may be used on the wall framing anchor bolt  121  to secure a structural connection between the foundation cistern and the building, or structure, above it. The opening used to house the galvanized bolt  137  is cast oversize in order to follow with a grouted connection of the imbedded bolt  137  used for connecting the foundational cistern assembly to adjacent foundation components. This method is used for other openings in concrete described in this invention. Reinforcing bars  120  are present in the top cover  101  as identified previously. The 8 by 8 lintel  122  is also identified (as described in  FIGS. 2   a - 2   d ). A ½ inch shim space  126  is present to allow leveling of the top cover  101  once it is placed on the base unit  118  of the present invention, which allows a means of leveling the top cover  101  to required building tolerances. An injection channel  132  is provided for the purpose of completely filling the oversized opening with epoxy grout to assure complete coverage of the bolt  137 . 
       FIG. 5   b  shows a plan section at the lower galvanized bolt  137 , showing the connection of the base unit  118  and the pre-cast concrete wall panel  119 . A one-inch cast opening  141  may be sealed with epoxy grout  139  after connection. The one-inch cast opening  141  is placed 4½ inches from the bottom of the top cover  101  of the unit and 4½ inches from the bottom of the base unit  118 , as in one preferred embodiment. As shown, the monolithic turn down edge  113  portion of the top cover  101  is used, as in one embodiment. The 11/16 opening  148  is placed 4½ inches from the outside edge of the pre-cast concrete wall panel  119 , and is directed through the pre-cast concrete wall panel  119  and into the top cover  101  for about 5 inches, in the monolithic turn-down lintel  122  portion of the top cover  101 , as in one preferred embodiment of the invention. The lower cast opening  148  may have a galvanized bolt  137  (in one preferred embodiment a ⅝ galvanized bolt), that is secured by a nut and washer  127  (and in one preferred embodiment, a 1¾ inch washer) and connects the pre-cast concrete wall panel  119  to the base unit  118  of the foundational cistern. The opening  141  may be filled with epoxy grout  139  in the finished product of the present invention. The shim space  159  between the top cover  101 , base unit  118  and pre-cast concrete wall panel  119  may be sealed with caulk  138  and accommodate shim washers  135  (and in one preferred embodiment ⅛ inch thick shim washers), and sealant  133 . The number of shim washers can be adjusted to compensate for variations in distance between adjacent precast foundation components, i.e., the base unit  118  and pre-cast concrete wall panel  119 , as is apparent to one skilled in the art. In one preferred embodiment, the sealant  133  used in conjunction with the present invention is nominally about ½ inch thick wide and of a depth as prescribed by the sealant manufacturer, however it is contemplated that other sealants including elastomeric caulking and the like may be used and would be apparent to one skilled in the art. A similar bolt connection and injection channel  136  in the top cover  101  is also shown in  FIG. 5   a  which is intended to align adjoining base units  118  and top covers  101  of additional foundational cisterns vertically and can be employed for the attachment of the top cover  101  to other cistern units or pre-cast wall panels. 
     An elevation view bolt connection at the top cover  101  adjacent to a pre-cast concrete wall panel  119  is shown in  FIG. 5   c . An anchor bolt  121  secures a sole plate  130  (that is part of the subflooring for the structure above), to the pre-cast wall panel  119 , which is adjacent and level with the top cover  101  of the foundational cistern. In one preferred embodiment, the anchor bolt  121  continues 5 inches into the pre-cast wall panel  119  at its strongest location (corner). Other attachment means would be appropriate and are known by those skilled in the art. Between the underside of the sole plate  130  a compressible filler  134  is placed between the top of the cover unit  101 , where there is a monolithic turn-down edge  113 , and the underside of the sole plate  130  to form an infiltration barrier preventing exposure to convected outdoor unconditioned air. A retaining pin  131  restrains the bolt from being pulled out. Bolts may be held in place by injecting epoxy grout. In the space between the top cover  101  and pre-cast wall panel  119 , flat washer shims  135  may be used as needed to occupy the space  126 . Sealant or caulk  138  may be used to occupy the exterior and interior perimeter of that space. Between the top cover  101  and lower base unit  118 , shim space  126  is present to allow flexibility for leveling of the top cover  101  before the subflooring is placed. In one preferred embodiment, the shim space  126  is approximately ½ inch. 
     A detailed view of the connection between the base unit  118  and a pre-cast wall panel  119  is shown in  FIG. 5   d . To facilitate connection of the base unit  118  of the foundational cistern and a pre-cast wall panel  119 , an injection channel  132  (that is 5 inches deep into the base unit in the preferred embodiment) is used to accommodate insertion of the retaining pin  131  and epoxy grout. That bolt  137  may be held in place within the pre-cast base unit  118 , in part through the use of a nut and washer  127 , thence subjected to use after approximately 24 hours, as in one preferred embodiment. Other means of fastening and securing fasteners to the pre-cast wall panel  119  and base unit  118  are contemplated and known by those skilled in the art. This view also provides further detail as to the thickened and reinforced concrete corner  125 , which is present in all four of the base unit  118  corners. A shim space  159  is present in between the base unit  118  and pre-cast wall panel  119  that may be secured with sealant as previously described. Flat washer shims  135  may be used to occupy that space where the bolt  137  is placed between the base unit  118  and pre-cast wall panel  119 . Also note that the base unit  118  and pre-cast wall panel  119 , sit on a gravel base  106 , as depicted in  FIG. 3 . 
       FIG. 5   e  is a plan section at the lower anchor bolt. Continuous layers of rigid insulation  108  are adjacent to both the base unit  118  and pre-cast concrete wall panel  119 . Between the base unit  118  and pre-cast concrete wall panel  119 , a shim space  159  is present, which may be occupied by caulk  138  at its exterior locations to a depth as prescribed by the caulking or sealant manufacture, as is apparent to one skilled in the art. In one preferred embodiment, the shim space  159  is approximately ½ inch, and may be occupied by flat washer shims  135 . An opening to facilitate connection of the base unit  118  to the pre-cast wall panel  119  houses a bolt  121  that is secured to the pre-cast concrete wall panel  119  by a nut and washer  127 . This opening is located approximately 4 and ½ inches from the edge of the base unit  118  and pre-cast concrete wall panel  119  and may be filled with epoxy grout  139 . A second opening  136  in the base unit  118  is formed by use of temporary polystyrene filler at the channels  140  and may be used as an alternative bolt channel connection. These one-inch diameter opening injection channels and alternate bolt connection  136  may house a galvanized anchor bolt accessible for installation at the interior crawl space side of the wall. Reinforcing bars  120  that add rigidity to the foundational cistern are labeled for reference. The crawlspace  107  is also denoted to show the environment of the invention associated with the attached pre-cast wall panel  119 . 
       FIG. 6   a  shows a plan section at the embedded weld plates  162 , which provides an alternative to the bolted connections previously described. A fillet weld  149  is used to connect the two components, here a base unit  118  and pre-cast wall panel  119 , via a 6 inch by 6 inch weld plate  152 . A 6-inch deformed bar  151 , as in one preferred embodiment of the invention, facilitates the structural connection of the steel angle  162  to the concrete cistern. Reinforcing bars  120  are denoted in the cistern corner and used for increasing structural connection strength. Space between the cistern and the adjacent structure is adjusted by steel shims  150  and sealed with caulk  138 . An alternative bolt connection or cast-in and deformed bar  161  is also shown. A weld plate  152  forms a high strength connection between either two adjacent cisterns  118 , or a foundational cistern  118  and adjacent pre-cast concrete wall  119 . 
       FIG. 6   b  closely parallels the welded connection design purpose described in  FIG. 6   a . It has the primary function of joining two adjacent base units  118 , along with their respective top covers  101 . This combination thereby avoids the need of exposing any connection hardware penetrations to the stored rainwater. 
       FIG. 6   c  is an elevation view showing how the weld plate  152  is connected via two fillet welds  149 , the individual embedded steel angles  162 , which are each cast in their respective base units  118  or to a pre-cast wall panel  119 . As such, the base unit  118  and pre-cast wall panel  119  are shown resting on the gravel base  106 . As in  FIG. 6   b , isolation of all connection components from stored rainwater is achieved. 
     The top cover  101  and its relationship to the base unit  118  is further shown in  FIG. 7 . The anchor bolt  121  used to connect the top cover  101  to subflooring is shown. The reinforcing bars  120  that run horizontally through the top cover  101  are denoted. In one preferred embodiment, the reinforcing bars  120  are approximately 2 and ⅛ inches from the side edge of the top cover  101 , and approximately 2 and ¼ inches from the top edge of the top cover  101 . The reinforcing bars  120  are approximately 3 and ¾ inches from one another to form a square pattern, as in one preferred embodiment of the invention. As is well known in the art, other patterns of placing the reinforcing bars  120  varying in number and size may be used to accomplish the same task, assuring the structural integrity of the top cover  101 . The lower left reinforced bar is approximately 2 and ½ inches from the bottom edge of the top cover  101 , as in one preferred embodiment of the invention. The top cover  101  at its outer edge is overall approximately 8 and ¾ inches in the preferred embodiment of the invention. Portions of the top cover  101  that are not at the edges are approximately 3 inches thick in this preferred embodiment. The space between the top cover  101  and the base unit  118 , which is identified as a keyway seal or joint  146  in  FIG. 3 , is filled with nonshrink grout  153 . Proper infill of the keyway  146  with nonshrink grout  153  produces a shimming effect  154 . Such space is necessary to level the top cover  101  so it is appropriate to support the subflooring of the structure. The tapered uppermost wall of the base unit  118  is approximately 3 inches wide near the connection of the base unit  118  to the top cover  101 . The monolithic turn down lintel  122  provides lateral transfer of concentrated and uniformly distributed building structural loads, loads to pilaster columns  115 , and thickened corners shown in  FIGS. 1   a  and  1   b.    
     A detailed cross-section of the present invention is shown in  FIG. 8 . This illustration further depicts the relationship between the top cover  101  and base unit  118  of the foundational cistern, and the keyway seal at joint  146 . Reinforcing bars in the top cover  120  are shown at openings in excess of 3 inches in diameter, as well as knock out holes  129 , which may be present to allow the ingress and egress of material contained within the cistern. Sealant, nonshrink grout  153  and grout shims  154  are used to seal the top cover  101  to the base unit  118  after the top cover has been leveled  101  appropriately for the subflooring of the structure to be placed on top of it. The non primary load bearing monolithic down turn edge  163  is designed to carry approximately 60 pound live loads and approximately 10 pound dead loads transmitted over spans not exceeding approximately 16 feet of uniform loading. 
     Structures to be supported by the present invention, in one embodiment, would involve light framed Type V building construction, as is known in the art. Associated loads typically are anticipated to be continuous. Point loads can be accommodated as needed where turn down lintels  122  are present. Load transfer, in the preferred embodiment, would occur near the outside framing line of structures above and across a typical 2 by 6 dimensional sole plate  130  bolted to imbedded anchor bolts  121  per IBC code and equivalent requirements. These vertical structural loads from above the foundation cistern of the present invention would then be transferred onto the pre-cast concrete wall section of the foundation cistern located immediately beneath the anchored sole plate, which is to be secured via these embedded bolt connections (see  FIGS. 5   a ,  5   c ,  5   d , and  5   e ). 
     Currently, typical septic tank vertical wall sections are a minimum of 2¾″ in thickness. By comparison, Superior Wall pre-cast sections, that may be used in one embodiment of the present invention, are using about 1¾″ thick sections. The IBC code table 1805.5 (1) requires a minimum of 7½″ thickness of plain concrete to restrain unstable backfill exceeding 4′ in height. Assuming a design constraint of a maximum backfill depth of less than 4′, local building officials can approve use of engineered (depth dimensions exceeding the 2¾″ minimum) vertical septic tank walls, as may be used in one embodiment of the present invention. Thickness of the walls of the present invention may vary as required to restrain less than four feet of unbalanced backfilled soil, while addressing lateral load reactions from various dynamic loads. 
     Either ⅝″ diameter bolt cavity spaces or embedded plates with attendant deformed bar anchors (similar to pre-cast concrete tilt wall components) would be cast or “let-in” the exposed surfaces of the upper and lower outside corners of each foundation cistern bearing wall in one embodiment. These bolts, or plates, when properly aligned, would enable individual foundation cistern units to be attached to one another in this embodiment (see  FIGS. 5   b ,  5   c ,  5   e ,  6   a ,  6   b , and  6   c ). Once connections are completed, it is anticipated the attached series of foundation cistern tanks would then be capable to reacting to differing soil bearing pressures and building loads imposed from above, in unison (see  FIG. 1   a ). That is to say their attached exterior concrete walls would serve as a continuous structural diaphragm up to a specified design load limit to be governed by the overall length of the attached foundation cistern array, and point loads being imposed by building framing above. 
     Live load characteristics affecting the individual units of the present invention must be taken into consideration, as the foundation cisterns are planned for use as water containment vessels having a fill level of up to 4 feet in depth, in one embodiment. In one embodiment of the present invention, total loads acting on the bearing soil include: LL and DL of structure above, LL and DL of foundation cistern including up to 1,500 gallons of water in a nominal  12  foot by 4 foot plan area at the floor of the cistern, and DL of gravel all cumulatively acting on bearing soil. 
     Moreover, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Thus, it is intended that the invention cover all embodiments and variations thereof as long as such embodiments and variations come within the scope of the appended claims and their equivalents.