(PTY) LTD
There is no fast rule in respect of any design or size of french drain; therefore, the following suggested data is given as a guideline only, and is applicable when read in conjunction with our copyright sketch plans.
The depths and lengths of an herringbone configuration may vary according to site conditions, such as the quantity of water being discharged and soil permeability. Further, the advantages to be considered in the design/location of a french drain are (a) an high percolation rate of the soil in the area and (b) of prolific vegetation in the area such as evergreen trees or any other form of growth with an all year round water demand. Alternatively, in the planning stages it might well be advantageous to locate the herringbone drain beneath a garden or lawn.
(1) Diameter (110, 75 or 50mm) and lengths of piping may vary according to soil conditions and volumetric flow.
(2) Standard domestic kit form comprises 2,00 metres X 110mm or 75mm diameter plain pipe from septic tank to soakaway, followed by 16,00 metres specially perforated 110mm or 75mm diameter piping and fittings.
(3) Grease trap, piping and related fittings optional extra items.
(4) Soakaway/French drain should not be located less than 2,00 metres from septic tank, but may be located on a downward slope as far as desirable for convenience of site lay-out.
(5) All sections of drainage work may be extended to suit site conditions.
(6) All junctions and joints loose fitted - PVC welding not required.
(7) On occasions where the French drain may not be constructed near a borehole, or close to a public stream, or in solid rock, we are able to design and supply an holding tank to be located behind the septic tank, complete with a submersible pump and float switch to transfer the fluid to a suitable site.
EXTRA OPTIONAL ITEMS - PRICES ON REQUEST
(A) Grease trap - plus gulley head, if required.
(B) Piping 110mm or 75mm diameter.
(C) Bend 45 degree X 110mm or 75mm diameter.
(D) Junction 45 degree X 110mm or 75mm diameter.
Much has been written in the past by many respected authorities on the subject of design / location / advantages / disadvantages and other theories. It is thus that we emphasise that the basis of our suggested requirements should be accepted as being a combination of the knowledge we have gained "in the field" over past decades and all that has been written by others in researching rural sanitation.
Our "Poly-Rib" septic tank has been acclaimed by users as the ultimate solution to on-site sewage disposal, from townships and plot holders to informal settlements - giving the owner the equivalent of the "city dweller" type of sanitation at a fraction of the cost of a sewage connection and ongoing effluent removal charges.
Until recent years, it was common practice to dig as large a hole as possible and fill it with every size of boulder, brick rubble and stone in sight. Modern day methods have proved that the most efficient type of soakaway/french drain is one that creates the maximum area of wall surface, which permits the fluid to exit horizontally in all directions.
For example, in the past a hole of say 3 x 3 x 1 metres would necessitate an excavation of 9 cubic metres, producing a wall percolation area of 12 square metres; our design as per sketch (applicable to the "Poly-Rib" septic tank) produces approximately 35 square metres of wall percolation area for an equivalent of 9 cubic metres excavation. The advantages are thus incalculable over designs of yesteryears, and far more simple to construct.