Abstract:
A unitary or modular, pre-cast, drive-down pit system suitable for use in a heavy equipment wash installation. The completed pit collects runoff generated by the washing of heavy equipment such as construction, industrial, farming, or road-building equipment. The pre-cast concrete separation unit and separate wall sections have tongue and groove mating ends that facilitate assembling the pit and provide for sealing against leakage of water. The wall sections have built-in rebar attachment and water block elements at an angle so as to provide for a strong and waterproof bond with the ramp floor. The ramp floor is concrete, poured after installation of the separation unit and the wall sections to complete the finished drive-down pit. The separation unit has up to four chambers: a primary solids collection section; a secondary solids settling chamber; a free oil separating section; and a pump water holding section.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to solids and free oil/water separation devices. More particularly, the present invention relates to a pre-cast unitary or modular assembly forming a pit for the pretreatment of water in a washpad installation for construction equipment and the like. 
     2. Description of the Related Art 
     Recent legislation has imposed strict limitations on the release of pollutants. This is particularly true in sensitive watershed areas such as that for the Chesapeake Bay watershed area. Construction equipment, road building equipment, farm equipment, and the like tend to collect oil and grease on their surfaces, along with dust and dirt, some of which clings to the oil-covered surfaces. It is necessary to periodically wash this equipment with pressure washers, resulting in wash water polluted with dirt, gravel, stones oil, and greases. It is also desirable to recycle the wash water for use in the pressure washers. 
     In response to the environmental requirements, it has become common practice to provide a drive-down pit for separating the wash water from dirt, stones, and gravel by settling, and oil and grease by consumption with enzymes or use of skimmers. This pretreatment of the wash water is necessary, regardless of the type of equipment being used for the recycling and/or discharge of the wash water. Such pits have a primary separation section where stones, gravel, and clumps of dirt are allowed to sink to the bottom. It is necessary to periodically remove such coarse material by providing a ramp for driving down a front-loading tractor into the water-containing pit and removing this material by manipulating the bucket of the tractor and backing out of the pit up the ramp. 
     The free oil and grease float to the water surface and is captured and then consumed by enzymes placed in table form in the pit or skimmed from the pit and removed for proper disposal. The enzymes are effective during summer months, while skimming is used in colder weather. Pretreated water is pumped from the pit as dirty water drains into the pit from the wash pad. The pretreated water is further cleaned by various types of separation equipment to be recycled to the pressure washers or discharged. 
     It typically takes two to three weeks to build forms and pour the concrete to complete the construction of the floor, walls, and ramp of such a pit, costing valuable labor time and delaying the use of a wash installation. Water leakage is a problem due to the multiple pours required, which may undermine the pit. It would be desirable to provide a unitary or modular pit system which can be customized for any pretreatment requirements and which can be quickly installed with the elimination or minimization of concrete pouring. Such a system would eliminate the need for building concrete casting forms and eliminate water leakage. 
     Thus a pre-cast drive-down pit system solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The present invention is a unitary or modular, pre-cast, drive-down pit system suitable for use in a heavy equipment wash installation. The installed pit collects runoff generated by the washing of heavy equipment such as construction, industrial, farming, or road-building equipment. The modular system has a pre-cast concrete separation unit and a drive-down section. The drive-down section has separate modular walls having tongue and groove mating ends for mating with the separation unit. The tongue and groove mating ends facilitate assembly of the pit and provide for positive sealing against leakage of water. The walls have built-in rebar attachment and water block elements at a predetermined angle so as to provide for a strong and waterproof bond with the ramp floor. The ramp floor is concrete, poured after installation of the separation unit and the wall sections to complete the finished drive-down pit. The separation unit has up to four chambers: a primary solids collection chamber; a secondary solids settling chamber; a free oil separating chamber; and a sump pump chamber. The unitary system includes the separation unit and the drive-down section cast of concrete as a single unit. 
     The separation unit design provides for a hydraulic line depth to accommodate the apparatus to remove heavy solids. This depth is determined by overflow dams for flow of water successively traveling between the separation chambers, the free oil separating chamber having a standpipe and conduit for feeding the sump pump chamber of the separation unit. The separate wall sections feature an inner surface with a vertical face and an outer surface having an outward protruding footing or base. The modular nature of the pre-cast collection and separation pit of the present invention allows a quick leak-proof installation for the collection and pretreatment of water from a washing pad. 
     It is an aspect of the invention to provide improved elements and arrangements thereof for the purposes described which is cost effective, dependable and fully effective in accomplishing its intended purposes. 
     These and other aspects of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an environmental side elevation view partially broken away, of the modular drive-down water separation and purification pit of the present invention. 
         FIG. 2A  is a plan view of the pit installation of  FIG. 1 , with an equipment room such as a pump and filter facility and wash pad. 
         FIG. 2B  is a plan view of the drive-down water separation pit of  FIG. 1  with grates and railing in place. 
         FIG. 3  is a sectional view of the water separation unit of  FIG. 1 . 
         FIG. 4A  is a detail view of the water separation unit connection with a drive-down wall unit of  FIG. 1  prior to assembly. 
         FIG. 4B  is an end view of the drive-down pit wall units of  FIG. 1 . 
         FIG. 4C  is a front elevation view of the pit wall units and water separator unit as joined and before construction of ramp. 
         FIG. 5  is a detail view of the connection of the water separation unit and the drive-down pit wall unit of  FIG. 1  in plan view. 
         FIG. 6  is a plan view of another embodiment of the water separation unit of the invention. 
         FIG. 7  is a side elevation view of the drive-down pit wall unit of  FIG. 1 . 
         FIG. 8  is a diagrammatic detail view in elevation of the finished connection between the water purification unit, the drive-down pit wall unit, and the poured ramp of  FIG. 1  as joined. 
         FIG. 9  is an environmental side elevational view, partially broken away, of another embodiment of the present invention. 
         FIG. 10  is a plan view of the embodiment of  FIG. 9 . 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is unitary or a modular, pre-cast, drive-down pit system suitable for use in a heavy equipment wash installation. 
     Referring to  FIG. 1 , there is shown a side elevation, view, partially broken away, of the modular drive-down pit system of the present invention as installed, generally referred to by the reference No.  10 . Modular drive-down pit system  10  includes a generally rectangular separation unit  12  and pit wall units  14 . Water separation unit  12  has a front wall  16 , an intermediate wall  18  and a rear wall  20 , all between sidewalls  22 . Sidewalls  22  extend equally and substantially forward of separation unit front wall  16 . A rear longitudinal wall  24  is parallel to and spaced from sidewalls  22 , extending between intermediate wall  18  and rear wall  20 . Separation unit  12  has a horizontally disposed floor  26  extending from the front ends of sidewalls  22  to the rear wall  20  to form an integral unit. 
     The forward portions of sidewalls  22  and floor  26  define a primary solids separation section  28  for separating heavy components from the wash runoff water entering pit  10  through settling. The front wall  16 , intermediate wall  18 , sidewalls  22 , and floor  26  define secondary solids separation section  30  for separating finer dispersed solids from the water through settling. Rear longitudinal wall  24  separates the section formed defined by intermediate wall  18 , rear wall  20 , sidewalls  22  and floor  26  into an oil separation section  32  and a sump pump section  35 . 
     An oil separation standpipe and exit conduit  34  extends from a point proximate the floor of oil separation section  32  and connects oil separation section  32  with sump pump section  35  at hydraulic level  52 . A submersible pump  36  is located in sump pump section  35  for removal of the pretreated water from the pit system  10 . Water separation unit  12  has a handrail  38  extending along the upper surface of sidewalls  22  and front wall  16  to surround primary solids separation section  28 . 
     The sidewalls of pit wall units  14  each have an outward-extending footer  41  along the lower portions of respective pit wall units  14 . Each sidewall  40  has an imbedded ramp waterblock element  42  extending inward along a sloping angle from the forward end  64  to the connection joint  48  connecting water separation unit  48  and pit wall units  14 . A series of rebar connectors  43  are embedded in each sidewall below waterblock element  42  and spaced therealong. A concrete ramp  46  is poured over a gravel bed G and backfill earth E to form a ramp section  44  and complete the installation of the modular drive-down water pretreatment pit  10 . 
     As shown, the ramp  46 , as poured, seals over waterblock  42  making a watertight joint. Rebar (not shown) is attached between the rebar connectors  43  extending from opposite sidewalls  40  of pit wall units  14  before pouring the concrete of ramp  46  for reinforcement of the ramp. A connection  50  is made between separation unit floor  40  and ramp  46  upon pouring the ramp  46 . The gradation of the wash pad is shown in hidden line  54  along the upper portion of drive-down pit  10 . Each pit wall unit  14  has a handrail  60  extending along its respective upper edge. Water runoff from the wash pad enters the pit  10  at runoff water entry  56 . Separation unit cover grates  58  cover the secondary solids separation section  30 , the oil separation section  32 , and the sump pump section  35 . 
     Referring to  FIG. 2A  there is shown a plan view of a construction equipment wash installation having a wash pad and circulation system  70  shown in connection with the inventive modular drive-down water pretreatment pit  10 . Wash pad and circulation system  70  has a sloping wash pad  72 , preferably of concrete. A catwalk  74  divides the wash pad  72  and the pit  10  for ease in pressure washing of equipment by a workman. An equipment room  76  contains pumps, filters, and conduits of conventional configuration for final filtering of recycle water from pit  10 , supplying wash nozzle supply line  78  and wash nozzle  80  with filtered water for washing equipment parked on wash pad  72 . A rainwater diverter  82  is put in place when the pit and circulating system are not in use to divert rainwater draining from pad  42  to pit  10 . A closure  84  is placed so as to complete the channel between the pad  72  and pit  10  at runoff water entry  56  when the rainwater diverter  82  is removed for washing operations. 
     An electrical pump service conduit  88  is connected with pump  36  through pump electrical service aperture  86  in the sidewall  22  of pump water collection section  35  for electrical service supplied from pump and filter facility  76 . A pump water conduit  92  conducts water from sump pump  36  through pump water conduit aperture  90  in sidewall  22  and into equipment room  76 . A filter flush return conduit  96  extends from pump and filter facility  76  and through filter flush return line aperture  94  in sidewall  40  so as to return water used in periodic flushing of filters to ramp section  44  for separation of solids from the flush water. Apertures  86  and  90  may be located in rear wall  20  as desired and the unit  12  may be supplied with both pairs of apertures, each filled with knockout plugs for fitting different size conduits. 
     Referring to  FIG. 2B  there is shown a plan view of the modular drive-down heavy solids separation pit  10 . A stream of water, lighter solids, and free oil flows from primary solids separation section  28  over cutout dam  98  in front wall  16  at the hydraulic fill level (see hydraulic fill line  52  of  FIG. 1 ) and into secondary solids separation section  30 . The water and free oil then flow over cutout dam  100  at the hydraulic fill level and into oil separation section  32 . The oil floats and collects on the surface of the water while water flows up through the standpipe of standpipe and conduit  34 , and through the conduit to pump water collection section  35 . Grates  58  are shown covering sections  30 ,  32 , and  35  for safety. Handrails  38  and  60  surround the primary solids separation section  28  and the pit wall units  12  for safety. 
     Referring to  FIG. 3 , there is shown a sectional view of the water separation unit  12 . The oil separation section feed cutout dam  100  is shown providing access between secondary solids separation section  30  and oil separation section  32 . Separation unit grating ledges  104  are shown cut into walls  16 ,  18 ,  29  and sidewall  22 . Water block strips  102  are shown as hidden lines between the floor  28  and outer walls including rear wall  20  and sidewalls  22 . Another water block strip  102  is embedded in the floor  28  at connection joint  50  (see  FIG. 1 ). A series of spaced rebar connections  106  are embedded in floor  28  at points spaced above water block strip  102  (see  FIG. 4C ). These rebar connections  106  may be located above the water block element  102  as an alternative. The floor of concrete ramp  46 , when poured, surrounds the water block strip  102  forming a waterproof joint. Rebar may be attached to rebar connection  106  and extended at an angle upward to reinforce the ramp  46  when poured with cement. This rebar may be attached at right angles to the crosswise rebar described as attached to ramp rebar connectors  43  as discussed above (see  FIG. 1 ). 
     Referring to  FIGS. 4A–4C  and  FIG. 5 , there is shown a side elevation view illustrating the wall connection  48 , a rear elevation view of the spaced pit wall units  14 , a front elevation view of the assembled pit wall units  14  and separation unit  12  as assembled, and a detail plan view of the wall connection  48 , respectively. As seen in  FIGS. 4A and 5 , each wall  40  of pit wall units  14  has a tongue  110  extending rearwardly along its rear end  66 . Separation unit sidewalls  22  each have a groove  112  at its forward end  68 . Groove  68  extends to the floor  26  of separation unit  12 . Steel skid plates  118  are located below the joint to allow easy assembly of tongue  110  into groove  112 . Spacing bolts  114  are imbedded into groove  114 , the heads of which act as spacers within the joint  48  for sealant  134 . 
     Steel securing guide straps  122  are mounted on opposite sides of each wall  22  and extend forwardly from separation unit sidewall forward ends  68  having flared guide ends  124  for receiving and centering walls  40  of pit wall units  14 . Guide straps  122  are mounted into walls  22  by securing bolts  128 . Once walls  40  are mated with walls  22 , additional securing bolts  128  are introduced through guide straps  122  and secured into walls  40 . Chamfers  130  at the outer corners of walls  22  and chamfers  132  at the outer corners of walls  40  expedite the introduction of sealant  134  to form a waterproof joint  48 . 
     As best seen in  FIG. 4C , water block strips  102  are embedded in the front end of floor  28  and extends between footers  41  of sidewalls  40 . Also, rebar connections  106  are embedded in the front end of floor  28  and extend forward and upward therefrom. The rebar connections are spaced along floor  28  between footers  41  of sidewalls  40 . The rebar connections  43  are embedded in walls  40  and spaced below embedded water blocks  42  of pit wall units  14 . Cutout dam  98  in water separation unit front wall  16  establishes the hydraulic level(see  FIG. 4 ) and allows water, free oil, and fine disperse solids to pass from the primary solids separation section into the next secondary solids separation section. 
     Referring to  FIG. 6 , there is shown a plan view of another embodiment of the water separation unit of the present invention referred to by the reference No.  140 . Water separation unit  140  is identical in construction and features as water separation unit  12  described above with the exception that there is a single section  132  acting as a free oil separation section and a pump water collection section, the pump  30  being at the side opposite the feed cutout dam  100 . There is no wall comparable to the rear longitudinal wall  24  and no standpipe and conduit  34  as in the water separation unit  12 . Enzyme tablets or skimming is used for free oil removal and the submerged pump  30  pumps treated water from the lower portion of the section  142 . A large grate  58  covers the entire oil separation and pump water section  132 . 
     Referring to  FIG. 7 , there is shown a side elevation view of the inner side of wall  40  of a pit wall unit  14 . Waterblock  42  is embedded in cement wall  40  and slopes downward from wall forward end  64  to wall rear end  66 . Imbedded rebar connectors  43  are shown spaced along and under waterblock  42 . The concrete ramp  46  to be poured is shown in ghost lines. The washpad grade line  54  leads to the wash water runoff entry  56 . 
     Referring to  FIG. 8 , there is shown a diagrammatic detail view of the completed joints  48  and  50  of  FIG. 1 . Concrete ramp  46  has been poured with waterblock strip  42  and rebar connection  43  extending into the poured concrete ramp  46 . Waterblock strip  102  is recessed in the forward edge of separation unit floor  26  (see  FIGS. 3 and 4C ) and the extreme rear end of waterblock strip  42  bears against strip  102  to form a waterproof joint. Rebar connectors  106  is embedded in the forward edge of separation unit floor  26  and engages the poured concrete ramp  46  (connected rebar extending from rebar connectors  43  and  106 ). Sealant  134  surrounds tongue  108  on three sides and then extends inward and outward between wall rear end  66  and separation unit tongue receiving groove separation unit sidewall forward ends  68  (see  FIG. 5 ). The head of spacing bolt  114  provides spacing for sealant  134 . Securing guide straps  122  secure sidewall  22  to wall  40 . 
     Referring to  FIGS. 9 and 10 , there is shown a side elevation view, partially broken away, and a plan view, respectively, of another embodiment of the drive-down pit system of the present invention as installed, which is pre-cast as a single unit generally referred to by the reference No.  210 . Unitary drive-down pit system  210  includes a generally rectangular separation section  212  and a drive-down section  214 . Water separation section  212  has a front wall  216 , an intermediate wall  218  and a rear wall  220 , all between sidewalls  222 . Sidewalls  222  extend equally and substantially forward of separation section front wall  216 . A rear longitudinal wall  224  is parallel to and spaced from sidewalls  222 , extending between intermediate wall  218  and rear wall  220 . Separation section  212  has a horizontally disposed floor  226 . 
     The forward portions of sidewalls  222  and floor  226  define a primary solids separation section  228  for separating heavy components from the wash runoff water entering pit  210  through settling. The front wall  216 , intermediate wall  218 , sidewalls  222 , and floor  226  define secondary solids separation section  230  for separating finer dispersed solids from the water through settling. Rear longitudinal wall  224  separates the section formed defined by intermediate wall  218 , rear wall  220 , sidewalls  222  and floor  226  into an oil separation section  232  and a sump pump section  235 . 
     An oil separation standpipe and exit conduit  234  extends from a point proximate the floor of oil separation section  232  and connects oil separation section  232  with sump pump section  235  at hydraulic level  252 . A submersible pump  236  is located in sump pump section  235  for removal of the pretreated water from the pit system  210 . Water separation section  212  has a handrail  238  extending along the upper surface of sidewalls  222  and front wall  216  to surround primary solids separation section  228 . 
     For construction purposes, rebar loops or the like (not shown) may be embedded as attachments for grasping by a crane in the upper wall surfaces of the water separation section and the drive-down section  214 . These attachments may by cut away after installation. 
     Drive-down section sidewalls  240  extend forward from the front portions of separation section sidewalls  222 , and drive-down section floor  241  extends forward from the front portion of separation section floor  226 (see  FIG. 10 ). Imbedded rebar  243  is shown reinforcing ramps  246  and may be employed throughout the structure of unitary drive-down pit  210  as desired. Drive-down section ramps  246  extend inward from sidewalls  240  and are spaced by drive-down void section  312  forming inner ramp sidewalls  314  extending upward from drive-down void floor  316 . Drive-down section ramps  246  slope downward from wash pad entry  256  in drive-down front wall  264  ending at separation section  212 . Drive-down section void floor  316  extends rearward from front wall  264  and joins separation section floor  226 . Drive-down void section  312  reduces the weight and materials requirements of the unitary pre-cast separation pit  210 . The treads or tires of a front load vehicle bridge the drive-down void section  312  and are supported by drive-down ramps  246  during vehicle entry, solids oval, and vehicle exit. 
     The gradation of the wash pad is shown in hidden line  254  along the upper portion of unitary drive-down pit  210 . Each pit wall  214  has a handrail  260  extending along its respective upper edge. Water runoff from the wash pad enters the pit  210  at runoff water entry  256 . Separation unit cover grates  258  cover the secondary solids separation section  230 , the oil separation section  232 , and the sump pump section  235 . 
     Referring more particularly to  FIG. 10 , a stream of water, lighter solids, and free oil flows from primary solids separation section  228  over cutout dam  298  in front wall  216  at the hydraulic fill level (see hydraulic fill line  252  of  FIG. 9 ) and into secondary solids separation section  230 . The water and free oil then flow over cutout dam  300  at the hydraulic fill level and into oil separation section  232 . The oil floats and collects on the surface of the water while water flows up through the standpipe of standpipe and conduit  234  and through the conduit to sump pump water collection section  235 . Grates  258  are shown covering sections  230 ,  232 , and  235  for safety. Handrails  238  and  260  surround the primary solids separation section  228  and the drive-down section  212  for safety. 
     Pump electrical service line aperture  286 , pump water line aperture  290  and secondary solids section feed conduit  298  are optionally pre-cast in unitary drive-down pit  210  to serve the same functions as electrical service line aperture  86 , pump water line aperture  290 , and secondary solids section feed conduit  98  as described above in the embodiment of  FIG. 2   b.    
     The pre-cast unitary or modular units may be of any desired size to form a pit with appropriate capacity. As an example, the overall length of the pit may be 432″ with a water separation unit length of 144″ and pit wall unit lengths of 288″. The overall height of the pit is 42″ and the width is 102″. The water separation unit has a floor, front wall, intermediate wall and rear wall of 6″ in thickness. The water separation unit sidewalls are 6″–8″ in thickness as are the walls of the pit wall units. The ramp has a slope of 1¼′ per lineal foot. The wash pad grade has a slope of ⅛″ per liner foot. 
     The length of the primary solids separation section is 54″. The length of each of the secondary solids separation section, the free oil separation section, and the pump water collection section is 36″, respectively. The width of the primary and the secondary solids separation sections is 86″, respectively. The free oil separation section is 4′10″ and the pump water collection section is 30″ in width, respectively. The steel skid plates under each pit wall joint is ½″×12″×24″ steel plate. The tongue of the pit wall joint is 2½″ in width by 3″ in length by 41¾″ in height and extends to the top surface of the pit wall unit. 
     The depth of the groove in the forward ends of the water separation unit sidewalls is 3″ and the height is 42″. The grate size of the secondary solids separation section is 39½by 89½″. The spacer bolts are ½″×1½″ hex head bolts having heads of ¼″ in thickness, providing for ¼″ joint sealant space. The rebar is #6 rebar. The water block is plastic or robber strip of 4″ width by ¼″ thickness. The footers of the pit wall units extend 6″ outward from the foot of the walls and are 6″ in height, extending the length of the pit wall units. The hydraulic level in the pit is 24″ above the floor of the water separation unit and the section feed cutout dams are 24″ above the floor. The water entrance to the pit is 11″ below the top surface of the pit wall units. The poured surface of the ramp is six inches in thickness. The joint securing guide straps are 18″×2″×¼″ steel. 
     In the operation of the pit, solids collected in the primary solids separation section is periodically removed by scooping with the scoop of a tractor as described above. The secondary solids separation section is emptied of collected fines be a pit cleaner suction device which transfers the collected fines to the primary solids separation unit. Enzyme tablets used to consume the collected oil are, for example, Biopucks, available from Landa cleaning systems, Camas, Wash. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.