BACKGROUND OF THE INVENTION

A sewer system connects a source of wastewater, such as a private residence, to a sewage treatment facility. A wastewater collection system is what gathers the wastewater and rain run off and moves it to the sewage treatment facility. A conventional wastewater collection system uses a peak-flow concept in which wastewater moves the sewage to the sewage treatment facility as fast as the wastewater enters the system. ^' With minimal exception, the wastewater collection system sends the sewage immediately and directly to the sewage treatment facility. In practice, however, the supply of wastewater is not constant so that the sewage treatment facility experiences an uneven demand.

The uneven supply of sewage to the sewage treatment facility causes problems. Major precipitation events (thunderstorms, hurricanes, etc.) can supply so much wastewater that the sewage treatment facility cannot treat all of it. Unless the sewage treatment facility has substantial excess capacity, raw, untreated sewage flows out of the sewage collection system through storm drains directly into lakes, rivers and oceans, thus bypassing the sewage treatment facility entirely. Some sewer systems have been designed to rely on periodic floods to flush the sewage collection systems and prevent the supply lines from clogging. The result of such design can be large scale pollution of the environment. It has recently been estimated that every year 84 billion gallons of raw, untreated sewage bypasses New York City's sewage treatment facilities every year — the equivalent of 220,000 Olympic size swimming pools of pollution. While other cities have

SUBSTITUTE SHΞET

less sewage bypass, the damage caused by lesser discharges sometimes can be greater when, for example, there is not much fresh water to start with before it is polluted.

The problem can be much worse when the need for sewage bypass is not limited to rare instances. Conventional wastewater collection systems convey sewage at a variable rate that corresponds almost exactly to the rate at which it is produced. The variations in the rate of production is predictable and has daily, weekly or yearly cycles. It is known that an average community can generate half or more of the daily flow in a 2-4 hour period — usually in early evening when families are at home preparing meals, washing clothes, bathing, etc. and when restaurants and other evening activities are in full swing. The sewage treatment facility, however, only works so fast. The conflict between the wide swings in the rate of collection of wastewater and the limited rate at which the sewage treatment facility can process it has predictable consequences. For one, a (very expensive) sewage treatment plant has to be built with enough capacity to accommodate the maximum predictable sewage delivery. Much of its capacity is not used during off peak times — which is most of the time.

Another predictable consequence of existing wastewater collection systems is that predictable variations in the production of sewage can exceed the capacity of the sewage treatment facility as the amount of sewage produced increases from year to year. Such increases, caused by, for example, a growing population, can result in raw, untreated sewage bypassing the sewage

treatment facility on a regular basis. The timing and amount of sewage bypass are not entirely unpredictable.

The areas experiencing the most rapid economic growth — such as the suburban and southwestern United States, the state of Florida as well as much of the "third world" — are regions that are chronically short of fresh water to start with. These developing regions simply cannot afford to contaminate what little fresh water they have with raw, untreated sewage. Existing sewage systems can nevertheless bring about precisely such pollution.

Existing wastewater collection systems can be classified into different types. Gravity systems use gravity to bring the wastewater to the sewage treatment facility. Gravity systems also collect storm water, which serves to flush the wastewater collection system. Most common in larger municipalities, gravity systems can supply a treatment facility with ten times or more of the average amount of wastewater during a storm. Often most of this wastewater bypasses the sewage treatment facility and thus produces significant pollution. The sewer lines in gravity systems must be oversized to handle the peak-flow which adds to the expense of their installation. The oversized sewer lines also may lack sufficient flow during slack periods to scour the lines. This effect is particularly pronounced where seasonal or periodic fluctuations in population, common in recreational communities, cause drastic variations in the output of wastewater. The sewer lines often become clogged from grease solidification. The fermentation and decomposition of organic matter can cause the formation of sewage gasses, some of which, such as

hydrogen sulfide gas, produce a noxious odor in the com¬ munity, while others, such as methane, are flammable and therefore dangerous.

An alternative type of wastewater collection system uses pumps to force wastewater through the system. Called a pressure system, it need not rely on storm water for a periodic cleaning and thus can be made less subject to infiltration by storm water and less apt to have raw, untreated sewage bypass the sewage treatment facility during storms.

Pressure systems, however, also have problems. Pressure systems are subject to the same periodic variations in the rate of flow as are gravity systems. Engineers therefore must design sewage treatment facilities, sewer lines and safety systems far larger than normally needed. Pressure systems have the same problem accommodating growth as do gravity systems and thus can have the same need to periodically have raw, untreated sewage bypass the sewage treatment facility during times of peak flow.

In addition to having some of the same problems as gravity systems, pressure systems have problems all their own. The pumps needed to maintain a pressure system must be large enough to move all the wastewater as fast as it is generated. Most of the pumps in any given pressure system, may attempt to pump sewage into the same sewer lines simultaneously during peak periods. All pumps pushing sewage into the same line at the same time causes the pumps to work against one another. The result is less pump ef¬ ficiency, longer pump running time, shorter pump life and

inflated electric power consumption at peak periods. It also adds greatly to the cost of the sewer system. The high cost of pressure systems can be a prohibitive factor for smaller municipalities, "third world" countries, etc.

Another problem with pressure systems is what happens during a power outage when there is no electricity to operate the pumps. Pressure systems have only the small volume of pump basins. A minimal reserve capacity, often as little as 60 gallons or less, is all that can absorb wastewater until power can be restored. Official estimates from the United States Environmental Protection Agency (EPA) estimate that the average household produces 200 gallons of wastewater daily. Hence, pressure systems can convert otherwise minor power outages into emergencies by forcing raw, untreated sewage to back up into homes and businesses.

There is a need in the art for a better way to collect municipal sewage. Solving the problem requires allocating assets — sewer lines, treatment and storage facilities, pumps etc. — in a more productive manner. Many schemes for allocating such assets are possible and, indeed, many solutions have been tried. Each allocation scheme to date, however, has required sewer lines that are oversized so as to accommodate peak flows rather than optimally sized for continuous use. Growing communities still must go through the considerable expense of upgrading existing treatment facilities since they lack the ability to utilize existing capacity during off-peak periods. Municipal facilities are neither completely sealed against groundwater infiltration so that only wastewater requiring treatment is conveyed to the treatment facility nor

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prepared to avoid having to have raw, untreated sewage bypass the sewage treatment facility during more predictable peak demands. Likewise, it has not been possible to have the pumps in a pressure system cooperate in a way that maximizes efficiency and minimizes their run time, power consumption and wear.

Another type of sewer system is a septic system. These systems use a septic tank to perform an initial, partial treatment of raw sewage before discharging the partially treated sewage into the ground. Septic systems have several problems. There is a limit as to the density to which septic systems can be installed; exceeding this density causes the partially treated sewage to contaminate ground water. Septic systems are thus limited to relatively rural, sparsely populated areas. Septic tanks themselves cannot process all sewage. Over time there is a buildup of sludge in the bottom of septic tanks that must be pumped out periodically. Septic systems therefore are limited in applicability and troublesome in terms of maintainability while also having a well demonstrated ability to cause unacceptable pollution of the environment and specifically of groundwater that is often used for drinking.

SUMMARY OF THE INVENTION

The present invention involves locating one or more accumulator tanks along a sewer line and preferably at or near a source of sewage. Each tank has a pump that can repeatedly empty the accumulator tank of wastewater by pumping it out and into a sewer line. Each tank can store wastewater until a time when it is expedient to pump it to a sewage treatment facility by. The flow of wastewater through the collection system can be maintained at a constant rate or regulated in any way as desired. The sewage system is closed to infiltration of rain water so that, together with the regulated flow, there should be no need to have raw, untreated sewage bypass the sewage treat¬ ment facility.

The features of the present invention involve storing wastewater in an accumulator tank that is buried below ground and reinforced so as to be pumped dry repeatedly without deforming the tank. Pumps are located in or near the accumulator tank. The wastewater collection system can be controlled by having one or more pumps send the wastewater from its associated accumulator tank to the sewage treatment facility through a sewer line. The one or more pumps for the one or more accumulator tanks can be controlled using an open loop control system such as provided by a preset timer. Alternately, a plurality of accumulator tanks can be linked by way of a telecommunica¬ tions network to a control center to provide a closed loop control system. A digital computer can be programmed to operate the pumps so as to make the flow of wastewater more constant and to otherwise optimize the performance of the entire sewer system. The control center may receive

information from each accumulator tank, the flow reaching the sewage treatment facility, or other indicators, in a real time feedback loop to control the wastewater collection system.

The sequence in which different accumulator are emptied, however controlled, can be arranged to attain certain objectives. For example, pumping can be scheduled to avoid times of peak power consumption. Extended periods of low sewage generation in seasonal communities can be accommodated by delaying pumping until enough wastewater accumulates to scour the sewer line; this procedure should eliminate line clogging and the forming of dangerous and noxious gases. The reserve capacity of the accumulator tank can be made big enough to allow most service calls for events such as equipment maintenance to be made on a routine rather than emergency basis.

One embodiment of the present invention uses a single accumulator tank to enclose single or multiple pumps and can service multiple homes. The capacity of the ac¬ cumulator tank can be 1000 gallons or more. The accumulator tank collects wastewater using either gravity or forced flow. The accumulator tank has enough capacity to store the average output of six homes for 24 hours or longer. The sequence of activating individual pumps can be determined using known hydraulic analysis of the entire collection system so as to optimize flow, pumping ef¬ ficiency and energy savings. Individual pumps can be controlled in various ways such as by an electric timer in an open loop control system or by telemetry transmitted from a computer at a remote control center in a closed loop

control center. Manual overrides can also be provided in the event of a failure of the control system.

A desirable feature is a turnoff switch to shut off each pump when the wastewater reaches a predetermined minimum level in the accumulator tank. It is also possible to compensate for a malfunction in the timer or in the telemetry using a switch that automatically pumps out a set amount of the wastewater when it exceeds a predetermined level in the accumulator tank.

Another desirable feature is that the accumulator tank should be completely sealed so as to prevent any groundwater from infiltrating into the wastewater. Excluding groundwater and storm water, helps to ensure that there is no need for raw, untreated sewage to bypass the sewage treatment facility.

It is also a desirable feature that the accumulator tank have enough capacity to delay the need for pumping until the most optimal time. Meeting this requirement itself may often require that the accumulator tank hold all the wastewater produced during a known cycle. Such a cycle is usually a twenty-four hour period and can be less, such as a few hours, but is longer than individual discharge events. In this way the flow of wastewater from the accumulator tank to the sewage treatment can be made quite constant.

An advantage of the present invention is that it allows sewage treatment facility to operate at a more constant rate more of the time. Existing sewage treatment plants can thus treat greater amounts of wastewater without

having to incur the considerable expense of being enlarged. Another advantage is that pumping can be made more efficient by staggering the schedules of the pumps so as to avoid having numerous pumps operate at the same time on the same sewer line and thus pump against each other. The rate of flow from individual pumps increases, too, at the same time. Optimizing pumping sequences has the additional advantages of reducing the time during which the pumps must run, conserves energy and extends the life of the pump. Also, by scheduling pumping to avoid periods of peak electric power consumption, the present invention has the additional advantage of conserving electrical energy.

Another advantage of the present invention is that it provides the local sewer authority with a way to assure that the sewer lines are scoured by an adequate flow of wastewater. Proper scouring prevents line clogging plus hydrogen sulfide or other dangerous or various gasses from forming, thus providing the advantage of eliminating the noxious odors from this chemical action that plague some existing gravity and pressure systems. The present invention also has no need for storm water to flush the sewers and thus has the advantage of causing less water pollution.

The present invention also has an advantage over septic systems in that the grinder pump can be used to grind all the sewage to a fine slurry and pumps it to the treatment facility. There is no sludge to be hauled away as in conventional septic tank systems. Alternately, an effluent pump or sewage ejection pump can be used to eject the sewage directly into the sewer line. Either way, the present invention permits the effluent from one to six

residences or more to be collected in one accumulator tank and pumped to the treatment facility, whereas septic systems require a separate septic tank for each house. Perhaps the most important advantage of the present invention over that of septic systems, however, is that it works when septic systems cannot, such as when housing densities exceed the ability of the ground to absorb the output of the septic tank.

An added advantage of the present invention is lower costs for both equipment and installation when compared to conventional gravity or pressure sewer systems. Conventional pressure systems typically require a basin and pump system for each home, whereas the present invention requires only one pump for many homes, such as, for example, groups of four or six homes. Furthermore, the pump can be smaller and more economical because it need not work against other pumps operating at the same time on the same sewer line. The size of the sewer lines needed are also reduced since they need accommodate a more steady flow rather than the peak-flow, which results in a considerable saving in installation over both gravity and pressure systems.

Other advantages of the controlled flow method of the present invention over systems now employed include better utilization of the treatment facility resulting in reduced size and/or elimination of capacity upgrading costs. The present invention is fully compatible with existing sewer systems since it allows the full content of new sewer connections to be scheduled for delivery to the sewage treatment facility during off-peak periods. The present invention thus helps to reduce the dumping of raw

sewage bypass caused when the sewage treatment facility lacks capacity to handle increased peak flows resulting from growth.

The present invention also has practical advantage for local sewer authorities. Large capacity storage eliminates nearly all off-hour emergency service calls. Problems such as equipment failures and electrical outages and the like are not emergencies because the accumulator tank can store the wastewater for a long enough period of time to allow for a more normal response to a malfunction such as equipment failure or an electrical outage.

An advantage to controlling each pump from a central station, such as in a closed loop control system, is that telemetry can be made two way. Thus, trouble shooting can be done at the central computer using data from such as the remote sites as well as the sewage treatment facility and the flow rate can be adjusted in real time in response to the measured parameters. Two way telemetry also permits extensive data to be collected from the entire wastewater collection system. Backup systems, such as automatic timers, maximum and minimum wastewater level detectors in the accumulator tanks can compensate for any error in the telecommunications network or in the computer control system.

It is an object of the present invention to solve each of the foregoing problems with gravity and pressure sewer systems.

It is another object of the present invention to provide a way to process wastewater in a more continuous flow.

It is another object of the present invention to provide municipalities with a more economical way of building and expanding a wastewater collection system so as to better accommodate growth.

It is another object of the present invention to provide a way to arrange and use the assets of a sewer system that permits rational management and facilitates real time reallocation of those assets.

It is another object of the invention to control the flow of sewage to a wastewater treatment facility by distributing sewage storage and transmission assets so as to optimize the efficiency of a given sewage treatment system by enabling it to operate at a more or less continual rate.

These objectives, features and advantages of the present invention, and more, will become apparent from a more detailed explanation of one way of implementing the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a representation, in generalized form, of a complete sewer system using the wastewater collection system according to the present invention.

Figure 2 is a sectional view of one embodiment of an accumulator tank of the present invention.

Figure 3 is a top view of the accumulator tank shown in Figure 2.

Figure 4 shows a block diagram of one type of control system for an accumulator tank of the type shown in Figures 2 and 3.

DETAILED DESCRIPTION

Figure 1 depicts one way of constructing a wastewater collection system according to the present invention in a sewer system of, for example, the pressure system type. A main sewer line 101 delivers wastewater from a plurality of auxiliary sewer lines 102 to a sewage treatment facility 100 that is adjacent a body of water 50. One of a plurality of connection lines 103 connect one of a plurality of accumulator tanks 10 to the auxiliary sewer line 102 or to the main sewer line 101. One or more connection lines 104 connect a site of origin 105, such as a residence, to an accumulator tank 10.

Each of the connection lines 104 should be big enough to carry the maximum expected flow of wastewater from the site of origin 105 and need not differ from conventional sewer hookups. Each accumulator tank 10 can have at least enough capacity to store all the wastewater produced from all the sites of origin connected to it through a complete cycle. Such a complete cycle for private residences and commercial business establishments typically would be a full day but can be only a part of a day or many days or longer. There is no need for all the accumulator tanks to be the same size. Indeed, the size of the accumulator tank can be changed to accommodate different numbers or types of sites of origin as well as different anticipated flow volumes of wastewater. Conversely, it is possible to install one size of ac¬ cumulator tank in most of the wastewater collection system and then tc compensate for differences in the amounts or times at which the sites of origin 105 discharge wastewater

by changing the timing or frequency of pumping of a particular accumulator tank 10.

The auxiliary sewer lines 102 depicted in Figure 1 need only be large enough to accommodate a substantially constant flow of wastewater from the accumulator tanks which each services. The size required to accommodate a continuous flow of wastewater from the accumulator tanks 10 is necessarily less than that required to accommodate the combined peak flow from all of the sites of origin 105. Thus, the present invention allows for reducing the expense of sewer installation by reducing the size of the sewer lines. While it is still desirable even with the present invention, to design the sewer lines larger than necessary as a safety precaution just as for existing sewer lines, the present invention reduces the amount by which the lines must be oversized to accommodate unexpected flows. Safety considerations thus enhance the savings from reduced costs of constructing sewer lines as compared to more conventional gravity or pressure systems. The actual design of a sewer line can be arrived at using known methods once the foregoing flow rates are factored in.

The operation of the wastewater collection system shown in Figure 1 would be as follows. The sites of origin 105 would produce sewage at a first rate corresponding to whatever the rate happens to be. Wastewater coursing through the applicable connection line 104 moves the wastewater to the accumulator tank 10 for the particular site of origin. The rate of production of the sewage directed to each of the accumulator tanks 10 would be highly irregular and subject to peak flows that, it iε

contemplated, would be substantially above the average rate of flow.

In operation, the accumulator tanks 10 would store the wastewater from each of the sites of origin which supply it. At other times, determined by the timer at each accumulator tank and that may or may not correspond to the arrival of wastewater, each accumulator tank would dump its contents into the connection line 103 at a second rate corresponding to a predetermined discharge rate. The connection line transports the wastewater to the sewage treatment facility 100 by way of sewer lines 101 and 102. The times at which each accumulator tank is emptied would be determined so as to maximize the efficiency of the total sewer system, to compensate for a full accumulator tank, or other predetermined condition. In any event, the second rate of flow of wastewater from the accumulator tanks would be more constant than the rate of flow from the sites of origin and thus permit the sewage treatment facility to operate at a more constant rate for more of the time than possible if wastewater came there directly from the sites of origin at the rate of flow corresponding to the rate of production.

It is contemplated that the present invention would be implemented in a sewer system of the pressure system type. There is no reason, however, that the present invention could not be applied to a gravity system, too. Indeed, distributing accumulator tanks 10 in a gravity system would provide considerable advantage in regulating and smoothing the flow of wastewater and could significantly help to make the flow of sewage to the sewage

treatment facility more constant, or at least more controllable, in a gravity system, too.

It should be appreciated that Figure 1 illustrates but one embodiment of the present invention. There is no limit as to the location or capacity of accumulator tanks as used in a wastewater collection system. Figure 1 depicts the accumulator tanks 10 as being close to the sites of origin 105 which each services because such a distribution of accumulator tanks minimizes the size of the sewer lines 102. Likewise, the wastewater collection system depicted in Figure 1 minimizes somewhat the number of accumulator tanks 10 by arranging each in the center of a "star" configuration in which each receives wastewater directly from multiple sites using conventional sewer hookups. Other configurations are possible and, while not as ideal as that shown in Figure 1, may be more practical for reasons unrelated to the cost of sewer lines or accumulator tanks. For example, larger accumulator tanks could be positioned to store wastewater from the auxiliary sewer line 102 or a plurality of tanks could be distributed along the sewer lines 102 or 101 to even out peak flows to the sewage treatment facility 100. All these alternate arrangements provide accumulator tanks and means for accumulating waste water in accord with the present invention. Likewise, a wastewater collection system could operate with a combination of accumulator tanks and direct flow lines such as would happen by adding the accumulator tanks of the present invention to an existing wastewater collection system.

Figure 2 illustrates one possible construction of an accumulator tank 10 for use in the present invention.

The containment vessel of the accumulator tank 10 can be made of fiberglass or polyethylene reinforced with an embedded steel plate for additional support. As shown, the accumulator tank 10 has a capacity of, for example, 1200 gallons.

One way to provide the accumulator tank 10 with maximum strength is by using a spherical shape. A spherical shape also directs the wastewater to the center of the bottom of the tank where the pump(s) 12 can most efficiently remove it. A spherical accumulator tank can also be molded in two halves and nested for shipment to the installation site and joined by a flange 19. Of course, the accumulator tank 10 could have some other shape.

It is thought to be desirable, for aesthetic and health reasons, that the accumulator tank 10 be buried when installed whenever practical. It is therefore essential that the accumulator tank be strong enough that it not to collapse when, in use, it is repeatedly pumped empty. Conventional septic tanks are normally filled in use and thus rely on the pressure generated by their internal wastewater to offset the pressure of the ground. Thus, while the accumulator tank 10 of the present invention has the same size and shape as a known septic tank, it is necessarily more resilient to external pressure. Suitable accumulator tanks can be manufactured to predetermined specifications by fiberglass products manufacturers such as AK Industries in Plymouth, Indiana by, for example, modifying the design of an existing septic tank.

One way to implement the present invention is by enhancing the strength of an existing septic tank.

Conventional septic tanks are not designed to be pumped empty; rather, they depend on water pressure from water in the tank to offset the pressure imposed by the surrounding earth. Pumping a conventional septic tank empty while it is installed can cause it to collapse or at least to experience structural deformation which can result in rupture of the tank. Repeatedly emptying a septic tank is to cause structural deformations in most existing large volume septic tanks once they are buried after installation.

The present invention contemplates that one way to overcome this disadvantage is by enhancing the strength of an existing septic tank. For example, the "model S" fiberglass septic tank made by AK industries normally has walls that are h inches (about 6.25mm) thick. The tank allows for storing 1000 gallons (about 3,785 liters) and an additional 200 gallon (about 757 liters) free board volume above the liquid level at a 52 inch (about 1.3m) height. This tank can be modified to be emptied repeatedly by increasing the thickness of the wall to 3/8 inches (about 9.4mm) . The internal rail system 13 and base plate 14 provide additional internal support to the tank. The rail further joins the top of the tank at a cross brace 13' as shown in Figure 3 to further increase the internal support of the tank.

One of the advantages that is inherent in using the relatively large tank described above is that the amount of structural reinforcing needed is less as measured on a basis of per unit of volume. This is a relationship of the amount of structural reinforcement of the walls of the tank as a ratio of the volume of the tank.

It is to be appreciated that the accumulator tank 10 has a size comparable to that needed to supply septic service to a single residence. The present invention, in contrast, permits this tank to service multiple residences at once rather than just one. The expense added in reinforcing the tank over and above that needed for a conventional septic system is thus more than off set by increasing many fold the number of residences that it can service.

Figure 2 shows a submersible pump 12 suspended by a stainless steel or other type of rail system 13 within the accumulator tank 10. The pump can be, for example, a two- horsepower Barnes SGV grinder pump. Alternately, an effluent pump could be used such as a Barnes STEP (Sewage Treatment Effluent Pump) pump or a sewage ejection pump such as a Barnes type SE sewage ejection pump. All three of these types of pumps are made by made by the assignee of the present application. A moveable stainless steel or other type of piping 26 connects the pump 12 to a stationary PVC or other type of pipe for teeing through a hydraulic sealing flange 17 in the stainless steel or other type of rail system 13. A lifting device such as a rope 25 permits the pump to be removed from the accumulator tank 10.

It is thought that placing the pump 12 in the accumulator tank should be the most optimal positioning in requiring less force to empty the accumulator tank. While it should be possible to place a pump near but outside the accumulator tank to repeatedly empty it, such a position would encounter greater fluid resistance from the pump due

to the longer connection line needed to exert the pumping force on the wastewater. While such a solution could work and is within the scope contemplated for the present invention, it is not considered optimal. Having one pump empty more than one tank, while also possible, is thought to be less desirable due to the increased fluid resistance mentioned above. The point of the present invention is to distribute pumps with the accumulator tanks rather than use enlarged sewer mains to transmit pumping force to the accumulator tanks. The pump could empty the accumulator tank either by pressure or by vacuum suction and thus could comprise a centrifugal self priming, solids handling pump such as the 4C02D pump made by Burks Pumps of Piqua, Ohio.

A ball or other type of check valve 20, a PVC or other type of union 21 and PVC gate or other type of valve 22 connect the stationary piping to the feeder line 103 through a riser region 30 which has a higher elevation than the top of the accumulator tank 10. The riser 30 extends the service entry to ground level.

A PVC or other type of pipe 104 connects the accumulator tank to one or more of the sites of origin 105 to receive the wastewater. As shown, the connection is a conventional gravity feed. Other connections can be devised that would work to supply sewage to an accumulator tank 10 for use in the present invention.

It is possible to mount the pump 12, such as a grinder, sewage ejection or effluent pump, directly on the 14 base to reduce installation costs. It is considered preferable, however, to mount two pumps in the accumulator tank and to make both pumps removable for easier servicing.

Figure 3 shows a top view of the accumulator tank shown in Figure 2 with two pumps 12 installed. Having a second pump both reduces the load that each pump must bear as well as provide a backup in the event that one of the pumps 12 fails. It is also possible to use one or more sewage ejection pumps for the pump 12 so as to send the wastewater to the water treatment facility in the form in which it is received from the site of origin. Such an alternate arrangement, of course, requires that the one or more sewage ejection pumps have an adequate capability to handle solids. Suitable sewage ejection pumps include the type SE series made by the assignee of the present application and are believed to be known in the art and, therefore, need not be described further. Effluent pumps are less capable of pumping solids and therefore are thought at present to be less desirable in applications requiring the pumping of solids.

Referring to Figure 2 again, three level switches such as polypropylene mercury floats 24, 18, and 28 pivot on a PVC or other type float pole 23 to perform various level related functions within the tank 10.

Once the pump or pumps 12 are running the float 24 pivots downward to turn the pump or pumps 12 off when the liquid level 11 in the tank 10 reaches the minimum level.

In the event of a timer or telemetry start signal failure, float 18 pivots upward to turn on the pump or pumps 12 as a safety feature. In the event of any failure which allows the liquid to continue to rise float 28 turns on an alarm when the liquid reaches maximum level.

The present invention contemplates controlling the wastewater collection system by operating a pump located inside the accumulator tank. Figure 4 shows a block diagram that represents one such control. A switch 201 controls a pump 200. The switch 201 closes when the level of the liquid in the tank rises above a minimum level as measured by the float in the tank. The timer 202, which can be located at the pump control, starts the pump at a predetermined time by completing the circuit to a power source 205. Conversely, the switch 201 can open the circuit and turn off the pump 200 when the accumulator tank is empty. The timer 202 can be a part of a control panel 203 the exact construction of which can be implemented by a person having ordinary skill in the art using known principles.

The switch 201 can remain open if there is not enough liquid in the accumulator tank. An open switch 201 prevents the pump from starting even if the timer 202 attempts to initiate pumping. Conversely, an overflow switch 204 can override the timer 202 and turn the pump on in the event that the accumulator tank becomes full prior to the initiation of a pumping sequence at the predetermined time. Switch 201 can then shut off the pump when the tank is empty in the same manner described above.

The output of the accumulator tanks can be controlled by controlling the operation of the pump 12. In the embodiment shown in Figure 4, this control can be a simple timer mechanism 40 such an electrical clock. Such a clock preferably has a memory that can retain instructions for operation in the event of a power outage. The timer shown in Figure 4 can do this for awhile, such as 5 days or

longer, it being understood that shorter and longer times are also possible. The timer 40 can operate by commencing pumping at a predetermined time and continuing until the float 24 in Figure 2 indicates that the wastewater 11 has been emptied. The pump 12 then shuts off and waits for its next programmed start up before repeating the cycle. It is desirable that the accumulator tank be able to pump prior to its programmed pumping if it becomes full. Such an unusually high wastewater generation could be caused by any number of factors. In such an event, the mercury float switch 18 pivots upward and commences the operation of the pump. This operational signal overrides the preprogrammed timer. The duration of this emergency pumping can last until the tank is emptied as indicated by position 24 or until the level of wastewater 11 reaches some position intermediate to positions 23 and 24 as shown in Figure 1.

As illustrated, the accumulator tank 10 of the present invention uses a pump 12 to control the discharge of the wastewater 11 to feed a pressure sewer system of the type shown in Figure 1. There is no reason, however, why control over the discharge of the wastewater 11 could not be done in a gravity system with the control discharge being done using some other means.

An alternate method of controlling the accumulator tanks of the present invention involves connecting each to a telecommunications network such as a conventional telephone system which is illustrated in the most general of ways by the dashed lines 110 in Figure 1. Preferably the telecommunications network provides two-way communication between each of the accumulator tanks and a central control center. Figure 1 illustrates this link

with dashed drop lines 111 and 112 shown as connecting the accumulator tanks and sewage treatment facility, respectively, to the telephone system. The accumulator tanks can then direct information on the level of wastewater 11 both before and during pumping. The control center can generate telemetry to each of the accumulator tanks to control the pumping in such a way as to maximize the efficiency of the total wastewater collection system. While this telemetry could travel over existing telephone or conventional lines, other telecommunication lines such as fiber optic lines, CA-TV, cellular telephone or other remote radio microwave, laser optical or satellite connections, etc., or combinations thereof, can be fully adequate substitutes.

The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which iε intended to be protected should not be construed as limited to the particular embodiments described in the foregoing specification since these particular examples merely illustrate the invention defined by the following claims and in no sense to restrict the scope of the claims. The foregoing disclosure is not intended to restrict the range of equivalent structures or components but rather to expand both in ways never before thought of.