CESSPOOL

Abstract: An installation for underground dispersal of liquid effluent in which a cowling (2) has a number of spaced apart barriers (4) which act to dam liquid effluent to provide periodic inundation into side channels (17) which are provided by degradable structures such as cardboard. The installation is closed to limit ventilation and hence inhibit root growth within the confined area of the structure. The system is adapted to promote break down of sludge by providing accessible conditions for worms.

Description: CESSPOOL This invention relates to dispersal of liquid effluent including both a method of dispersal and an arrangement for effecting such dispersal using ground 5. soakage. There are many problems associated with dispersal of liquid effluent into a ground soakage installation. The liquid effluent in a typical instance emanates from a sewage treatment installation which is often 10. referred to as a septic tank. Liquid effluent resulting from sewage discharge into a septic tank system will conventionally carry significant suspension of solid particles which may subsequently settle and form what is usually referred 15. to as "sludge". Difficulties in effecting ground dispersal of such liquid effluent include initially preparing the ground for any distribution network adequate for a reasonable period of time to effectively disperse any 20. effluent. A next difficulty relates to the type of soil in which the dispersal is to be effected so that if the soil is generally of a non-absorbing or non-porous type, a very large dispersal area might be necessary 25. to provide adequate eventual soakage for an adequate sewage system. A further difficulty is that with any fixed conduit system providing for dispersal of the liquid, it has been hitherto considered that use of water seeking roots of above the ground plants or trees will eventually result in a total blocking of the conduits destroying any overflow capacity in a very short time. Further, sludge carried by any effluent will 5. settle and eventually block any distribution soakage area and there has been no previously considered effective economic system which might maintain adequate ground soakage capacity where sludge build up is being effected. The above problems are generally well known 10. and the result of such problems is that any liquid effluent dispersal arrangement within a ground soakage area can have a very short life whereupon a new installation must be provided or a sewage tank must be emptied by separate pumping and separate dispersal in another 15. area. I have found by using specific techniques that I can reduce the difficulties hitherto experienced with liquid effluent dispersal systems within a ground soakage area which have the result of either extending 20. the expected life of such a ground soakage dispersal installation or reducing the cost in that such a large dispersal area is not necessary for a given liquid effluent handling capacity either on a continuous or random peak basis. 25. An explanation of the respective features will assist in a full understanding of this invention. Perhaps the biggest difficulty with respect to dispersal is the sludge build up in that any ground soakage system will eventually become blocked by such 30. sludge and unless this is mechanically subsequently removed, the installation as such becomes useless for effective further dispersal. I have discovered that in certain conditions, some " types of earth worm can be active within sludge with a result that an otherwise impervious sludge settlemen layer will be broken up so as to become at least to 5. some extent porous and in the preferred instance, it has been found that the sludge will actually be devoured by such worms providing for reactivation of the surrounding ground area for liquid effluent dispersal. It is presumed in this case that the liquid 10. effluent is mainly water and that the effluent contains nothing that would be pathogenic for any type of earth worm that is appropriate. In order to encourage growth of worms, it has been found necessary that the soil shall not be saturated, 15. but if the installation promotes keeping such soil generally moist, then worm growth can be substantially enhanced. To understand how this can be achieved, consideratio of the normal pattern of effluent from either a domestic 20. residence or a commercial residence must be understood, and it will be appreciated that this is generally on a periodic basis in which substantial quantities of effluent will arise perhaps once or only twice during a twenty-four hour day. 25. Accordingly, this invention can reside in an installation for effecting underground dispersal of liquid effluent including a below ground soakage locality, and a conduit arranged to direct liquid effluent from an outlet through said locality, said conduit being shaped such that, 30. or having apertures therethrough such that liquid effluent flowing along the conduit can pass therethrough, the condui further having barriers at spaced intervals along the conduit adapted to act as, in each case a weir, to limit the passage of some liquid effluent there past, and channels extending from each side of the conduit, in each case having 5. an inner end in liquid communication with liquid which can be dammed behind each respective barrier and adapted to provide for extended ground soakage contact to a side of the conduit. By providing such weirs, a selected head of 10. effluent can be held in respect of each side channel so that such a head of water can be maintained over a significant period of time, typically for a significant part of a twenty-four hour period, but that a remaining period of such twenty-four hours will allow for exhaustion 15. of-such a head whereby the extended soakage area is alternatively inundated but then allowed to dry out to some extent. The discovery is that by selection of the weir height in conjunction with the soil type, the length 20. of the side channels and the spacing of the weirs together with a knowledge of the supply rate and periods between inundation from the source, can lead to such extended soakage area being able to be kept in a relatively moist state rather than maintained in a saturated state 25. and this can substantially promote worm growth in the vicinity. With such worm growth, this results in significant quantities of sludge being consumed by the worms keeping the channels effectively clear for subsequent passage 30. of liquid effluent. It will be further seen that such a result provides for a substantial soakage area that can be achieved somewhat more economically than has hitherto been the case in that the extended soakage area must be taken into account, and this can be provided with very economic means for providing the channels rather than a central conduit which must be permanent and therefore costly. 5. Apart from this of course, the fact that the soakage system will, with adequate worm growth, maintain soakage over a very extended time, means that it is economically much better than a system which will cease to be useful after a somewhat shorter period. 10. A number of other important aspects of this invention will be appreciated in the detailed description of the preferred embodiment, and by reference to claims appended to this specification. Reference is now made to the embodiment which 15. is described with the assistance of drawings in which - FIG. 1 is a partly cut away view of a part of an installation according to this embodiment prior to a top soil layer being located over the installation; 20. FIG. 2 is an end view in cross-section of the installation as shown in Fig. 1; and FIG. 3 is a side elevation of the installation .. specifically as in Fig. 2. Referring to the drawings, the installation 25. which is adapted to effect underground dispersal of liquid effluent provides a below ground soakage locality 1, and a conduit 2 which is in the form of a cowling made.of a relatively rigid plastics material which acts to maintain an open passageway therebeneath, the cowling having an open 30. bottom 3. The conduit 2 in the form of a cowling has a plurality of barriers 4 which are located at spaced apart intervals, each of the barriers extending across the width of the conduit 2, and in fact extending signi- 5. ficantly below the sides 5 and 6 of the cowling shape of the conduit 2. Each of the barriers 4 has a side portion 7 which is attached by rivet 8 to the side wall of the cowling shape of the conduit 2. 10. A lowermost edge of each barrier 4 is shaped to provide a flat bottom which can thereby provide a resting foot on the floor of any trench. Each barrier has a V-shape cut out portion 9, the lower edge of which at 10 is about two-thirds of 15. the height of the edge 5 of the conduit 2 above the foot of each barrier 12. The installation 1 as a whole is located in soil 13 which is cut in the form of a trench having side walls 14 and 15 and a bottom 16. 20. In practice the depth of the bottom of the trench 16 can be significantly greater than that shown in Fig. 2 and a technique known as .back-filling can be used so that where the soil is non-friable, it can be of advantage to assist general absorption and soakage 25. characteristics of the soil, especially beneath the dispersal area. Located so as to extend to each side of the conduit 2 are tubes 17 which are made from a biodegradable material, specifically in this case cardboard, with 30. the expectation that after a modest period of inundation with liquid effluent, these will disintegrate leaving, however, a channel through the earth. Each tube 17 is located so that an inner end 18 extends so as to be in liquid communication with liquid which can be dammed behind a respective barrier 4 and especially so that a lower edge 19 can be below 5. a lower edge of the weir 10. The tubes 17 are located so as to be on a downwardly outwardly inclined angle so that liquid which will pass through the conduit 2 will also tend to inundate the respective tubes 17 and channels resulting therefrom. 10. In an installation as shown, the first steps of installing such an installation are to dig the trench and back-fill earth so that there is an upper surface as at 20 with a flat apex portion at 21. It has been found advantageous to also provide 15. for corrugated cardboard with the corrugations extending in the direction of elongation of the conduit 2 to act as a first floor and subsequent to the location of the respective conduit 2 together with the tubes 17, there is located over all of these a further covering 20. of corrugated cardboard at 22, the purpose being to limit passage of earth into the space immediately below the sides 5 and 6 of the conduit 2. Once the installation is in place as in Fig. 1, the earth is then filled over the top of this arrangemen 25. so that the total installation as shown in Fig. 2 is fully below, and indeed substantially below, the upper ground level at 23. With the installation as shown, this is supplied from the outlet of a septic tank and is subject to 30. periodic inundation over conventional periods of a twenty-four hour day. A factor, however, in the total arrangement is that a furthest end of the conduit 2 is closed so that the total conduit apart from an entry inlet which is also beneath the ground although marginally accessible 5. to atmosphere, is that the whole system is therefore substantially not ventilated. Further, the direction and shape of members through which the liquid effluent is directed to flow is such that these will cause the effluent minimal 10. turbulence and in any event no free fall so as to cause undue mixing of the liquid with atmosphere. The two purposes here are, firstly, to keep the liquid effluent with as little entrained oxygen as possible and, secondly, to maintain the system with 15. as much retained gas as is possible resulting from decaying solids within the effluent. By maintaining the installation in such a condition, it is firstly found that if the liquid is kept essentially as anaerobic, this will inhibit root growth at least 20. in areas consistently inundated with such liquid. Further, if the area above such liquid is kept so as to maintain what effectively is a marsh gas atmosphere this has also been found to inhibit root growth into the enclosed area. 25. After some usage, consistent inundation has been found to cause the cardboard material to disintegrate and eventually rot. It is found that during this process, worm population build-up is such that the worms themselves will obtain 30. access to sludge retained within the tube and as the structure of the tube disintegrates, so however worm population and their associated burrows will develop to the extent that sludge build-up and worm populations will become compatible providing for a long-term continuing maintenance of channels in a laterally extending location to 5. the side of the main conduit 2. The method of use of such an installation is of course to provide this from time to time with liquid effluent so that there will be periodic inundation periods and drying out periods providing for maintenance 10. of moist areas compatible to worm growth in the soil to the side of a main conduit. It is found that with an installation of this type, its life can be significantly extended over an installation of similar length using presently known 15. techniques. Moreover, the installation according to this embodiment can be located in the immediate vicinity of trees having roots which are known to be aggressively active in seeking moisture and the trees in fact can 20. be adequately sustained by the moisture of the system without rapid blocking that has been hitherto the experienc in systems of previous design. The improvement then is to provide an arrangement which can be used in the close vicinity of trees, and 25. indeed provide sustenance to such trees or other plants, will be self-sustaining because of the active maintenance of worms and which will allow such involvement without reducing the effectiveness over a long period of time of the soakage ability.

Claims: 1. An installation for effecting underground dispersal of liquid effluent including a below ground soakage locality, a conduit arranged to direct liquid effluent from an outlet through said locality, said conduit 5. being shaped such that, or having apertures therethrough such that liquid effluent flowing along the conduit can pass therethrough, the conduit further having barriers at spaced intervals along the conduit adapted to act as, in each case, a weir to limit the passage 10. of some liquid effluent there past, and channels extending from each side of the conduit, in each case, having an inner end in liquid communication with liquid which can be dammed behind each respective barrier and adapted to provide for extended ground soakage contact. 2. An installation as in claim 1 further characterised in that the conduit comprises a cowling having an open bottom. 3. An installation as in either claims 1 or 2 further characterised in that the extended ground soakage contact is provided by channels initially effected from biodegradable structures. 4. An installation as in the last preceding claim further characterised in that the said biodegradable structures are comprised of cardboard. 5. An installation as in any one of the preceding claims further characterised in that each of the barriers is shaped to include a lowermost narrow portion providing for a channelling of overflow liquid effluent. 6. An installation according to any one of the preceding claims further characterised in that the said conduit is in the form of a cowling, the outer lowermost sides of which extend at a height higher 5. than an overflow level for each of the respective barriers. 7. An installation as in any one of the preceding claims in which each of the channels extending from each side of the conduit has its inner end at a level higher than an outer end. 8. An installation according to any one of the preceding claims wherein the conduit and channels are closed from access to atmosphere to the extent that they are non ventilated. 9. An installation according to any one of the preceding claims which is adapted by reason of closure of ends and otherwise arranged so as to substantially retain any gases given off during rotting of materials 5. within the installation. 10. An installation according to any one of the preceding claims wherein the arrangement is such that liquid effluent directed into the installation will be adapted to flow such that this will not be caused 5. to free fall. 11. An installation according to the last preceding claim wherein the installation is adapted to maintain the good effluent therein in an anaerobic state. 12. An installation substantially as described in this specification with reference to and as illustrated by the accompanying drawings.

Inventors: LUITJES GERRIT HENDRICUS, LUITJES, GERRIT, HENDRICUS
Applicants: LUITJES GERRIT HENDRICUS, LUITJES, GERRIT, HENDRICUS
Application year: 1986
Main classification: E03F11
IPC codes: C02F3, E03F1