AU2014100661A4 - Ground Drainage Method - Google Patents

Abstract

For buildings which suffer penetrating wetness in walls and floors below ground level, the method entails sinking a bore into the ground adjacent the wall to a depth deeper than the footing, inserting a permeable drainage duct in the bore, filling the space between the duct and the bore boundary with small stones and installing a pump at or near the bottom of the duct which intermittently pumps collected water through the conduit to waste. Figure 2 2014-06-17,C:\Users\SharlfeDocmnwnisSPECFICAIONSnorganinnpatnpd,7 PRIOR A-RT L; N t~36 '14

Description

1 TITLE OF INVENTION Ground Drainage Method TECHNICAL FIELD [0001] This invention concerns a method of remedial drainage for properties affected by the entry of water through walls and floors which are below ground level. BACKGROUND [0002] Many highset houses built on sloping blocks of land have at least one wall of the lower floor partially below the external ground level. Similarly, many older houses that have been raised and built in under also are partly below ground. [0003] It is quite common for these houses to leak and allow groundwater into the lower floor area. This is particularly prevalent in houses built after about 1960. The presence of water in the environment inside the building can make the area unusable and can create significant health risks for the occupants. As time passes this problem is affecting more and more dwellings. [0004] The construction process was to excavate and level the site to just beyond the perimeter of the building. Concrete footings and floors were poured and then perimeter masonry walls were erected. These walls were painted with a bituminous substance to provide a level of waterproofing to prevent groundwater from entering the building through the wall. The external area was then back-filled with gravel or soil and the surface landscaped as required by the owner. Sometimes an ag drain was installed at the base of the wall to drain away excess groundwater. This was the typical construction process during the 1960's, 1970's and into the 1980's. [0005] This arrangement appears to have had an effective lifespan of about thirty years. Over that time fine silt and sediment has settled into the ag drain (if installed) and drastically, or totally, reduced the function of the drain to remove groundwater from the site, The bituminous 2014-06-17,C:\Uers\Shadene\Documens\SPECIFICATIONS\mrgan innpatopd.1 2 substance painted on the wall became aged and brittle. It lost its elasticity. This means any movement of the building producing cracks, even cracking too fine to see, will result in cracking in the bituminous coating. This then allows water to contact, and pass through, the wall. Therefore a build-up of groundwater enters the house. [0006] Conventional methods to overcome this situation are impractical and in many cases almost impossible. [0007] The most common approach is to excavate the complete area of the wall and to re-apply new and probably more modern and sophisticated waterproofing product to the wall. This means the wall has to be completely exposed, and cleaned of all moisture and dirt ready to accept the new product. This work has to be done by hand because invariably there is insufficient room between the wall and the boundary for excavating machinery to work. Even allowing for the work to be done by hand, in many cases it is impossible because the lack of room or other infrastructure means the excavated area is not large enough for workers to be able to work at the base of the wall safely. Occupational Health and Safety legislation is quite detailed on safety requirements when entering and working in excavations. SUMMARY OF INVENTION [0008] The apparatus aspect of the invention provides a method of preparing a site on which a building stands, for drainage comprising sinking an upright bore in ground adjacent the wall of the building to a depth equal or greater than the footing of the building, inserting a permeable drainage duct in the bore, filling the space between the duct and the bore boundary with coarse particulate material which drains at a faster rate than the surrounding ground and installing a pump at or near the bottom of the duct which lifts drainage water through a conduit to waste. [0009] The bore is sunk using a water jet to create slurry and removing the slurry by vacuum extraction. [0010] The bore may be undercut. 2O14-06-1,C\Users\Sharkne\DocumenIs\SPECFICATIONSnrgan innpatipd,2 3 [0011] The end of the bore may be 100-1000mm deeper than the surface of the footing of the building. [0012] The pump is submersible and operation is intermittent in response to float control. Advantageous Effects of Invention [0013] 1. The installation dries the ground in contact with the building and prevents seepage. [0014] 2. The installation has a longer life than ag pipes. BRIEF DESCRIPTION OF DRAWINGS [0015] Embodiments of the invention are now described with reference to the accompanying drawings, in which: [0016] Figure 1 is a sectional side view of the prior art method of drainage. [0017] Figure 2 is a sectional side view of the method according to the innovation. DESCRIPTION OF EMBODIMENTS [0018] Referring to Figure 1, external masomy wall 2 stands on concrete footing 4 and floor 6 extends to wall 2. The outer face of wall 2 has a waterproof paint coating 8 which extends from footing 4 to ground level 10. [0019J An ag pipe 12 located at floor level in the ground runs along the wall and around the building to a place where the ground level is lower so that the pipe 12 can emerge and drain by gravity to a street drain or join the stormwater system of the building. The ground portion 14 is backfill. 2014-06-17,C:\UsersSharnefDlocuments\SPECIFICATIONSxmorganinnpaLnpd,3 4 [0020] Referring now to Figure 2, installation begins by excavating a hole 16 of approximately 450mm diameter to a depth at least a metre or more below the house floor level. This task is performed using vacuum excavation from the surface. This will enable the hole to be "belled out" so that it has a larger diameter at the base. The hole axis 18 is spaced from the wall, but the bottom of the hole 20 will increase in size so it reaches to the wall below floor level. Into this hole is lowered a PVC pipe 22 of approximately 300mm diameter. [00211 The lower half of this pipe is already cut with a diagonal array of slots 24, each approximately 3nun wide. The bottom of the pipe is capped by a plastic cap 26 with several small holes. The space between the outside of the pipe and the hole boundary is filled with clean stones 28 ranging in size from 5mm to 10mm. [0022] A Grundfos® submersible electric pump 30 is placed in the bottom of the pipe. The pump is controlled by float switches. The pump has a delivery hose 32 attached that rises to the surface and continues to a drainage point or other selected place of discharge. The pump has a built in power supply cord 34 that rises to the surface and connects to the household power supply system. The top of the pipe at ground level enters a square PVC 36 box that has a detachable/removable lid. [0023] The installation removes groundwater from the vicinity of the wall. Groundwater invariably travels via the easiest path or egress. In this instance groundwater near the wall 2 will find its way to the gravel 28 surrounding the pipe. As it passes through the gravel it will enter the pipe through the slots 24 cut in the pipe. It will then sink to the bottom of the pipe. [0024] When the water 38 in the pipe 22 reaches a pre-deterimined depth, say 500mm, the float switch will activate the pump 30 and the water will be pumped to the surface and be discharged through the surface drainage pipework which already exists to drain rainwater. When the pipe 22 is empty, the float switch will de-activate the pump 30. [0025] This process will repeat as required and the groundwater will never reach the floor level. It will therefore never lie against the wall and so will not penetrate the wall. The pump is 2014-06-17,Cn\Usrs\ShadennDocuts\SPECtFICATIONSunrgmnnpatwpd,4 5 designed to handle some fine solids, so any fine sediment or silt will be discharged with the water. [0026] It is to be understood that the word "comprising" as used throughout the specification is to be interpreted in its inclusive form, ie. use of the word "comprising" does not exclude the addition of other elements. [0027] It is to be understood that various modifications of and/or additions to the invention can be made without departing from the basic nature of the invention. These modifications and/or additions are therefore considered to fall within the scope of the invention, 2014-06-17,C:Users\Shrlen)ocuments\SPECIFICATIONSrnorganinnpat npd,5

Claims (5)

1. A method of preparing a site on which a building stands, for drainage comprising sinking an upright bore in ground adjacent the wall of the building to a depth equal or greater than the footing of the building, inserting a permeable drainage duct in the bore, filling the space between the duct and the bore boundary with coarse particulate material which drains at a faster rate than the surrounding ground and installing a pump at or near the bottom of the duct which lifts drainage water through a conduit to waste.

2. A method as claimed in Claim 1, wherein the bore is sunk using a water jet to create slurry and removing the slurry by vacuum extraction.

3. A method as claimed in Claim 1 or 2, wherein the bore is undercut.

4. A method as claimed in Claim 2 or 3, wherein the end of the bore is 100-1000mm deeper than the surface of the footing of the building.

5. A method as claimed in any one of Claims 1-4, wherein the pump is submersible and operation is intermittent in response to float control.

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