Sewerage and waste disposal

Dec.15.06

An important aspect of the new Building Regulations which would come into effect in 2007 is how to manage sewage and waste disposal.

The Building Regulations comprise the Code and Guidelines. The Code covers all buildings over 2500 sq. ft in area and more than two storeys in height. The contents of the code is of a highly technical nature and are mainly prepared for the major operators in the building industry – architects, engineers, etc. The Guidelines cover buildings/structures up to 2500 sq ft and two storeys high.{{more}}

According to the Code, every building intended for human habitation, or in which human beings are to be employed shall be designed to provide for a sewerage system of drainage to a septic tank or more efficient treatment facility of a design to be approved by the Chief Environmental Health Officer.

The developer must provide a system or systems to fully satisfy the need for sewage collection, treatment and disposal of effluent and sludge. The system (s) proposed must direct

special attention to the use of topography, the layout of the developments, roadways, and the location of treatment plants and outfalls.

Sewage and waste disposal facilities shall be designed and constructed in accordance with the Central Water and Sewerage Authority Regulation and with the public health legislations and regulations. Management of sewage and waste is different for each of the two categories however this series on the building code deals specifically with that for homes.

It is of particular note that ‘Pit Latrines’ are accepted under the building regulations as a means of disposal of sewage – contrary to the unfortunate rumours which were circulated throughout the state earlier in the sensitization programme. The Building Guidelines provide specific standards by which these should be built. Some of the issues that should be taken into considerations in constructing pit latrines are as follows:

The guidelines state that a pit latrine should not be located within 12 feet of a house or 50 feet from a river or other water course or storm drain.

The type of soil in which the latrine is to be constructed must be able to absorb the material and the guidelines provide a step-by-step instruction for conducting percolation tests to determine how the latrine should be constructed.

For example, if incorrectly constructed on a slope, the pit latrine could contribute to a landslide.

The guidelines also recommend a double-vault and well ventilated system. Essentially these are two pits dug side by side. The method to be used for ensuring there is no cave in is also specified in the guidelines. One pit is covered by the concrete slab which allows for decomposition of the waste in a dry state.

Ventilation is a critical aspect of the new design because gases build up in waste and can explode if not properly vented. The guidelines show how to properly vent a pit latrine by placing a PVC pipe painted black on the eastern side with a wire mess at the top of the pipe.

The reason for the pipe being painted black is so that the air in it would be rapidly heated and therefore rise. Secondly, placing the pipe on the eastern side allows for quick heating as the Sun rises in the east. Thirdly, flies will spawn in the pit and this pipe will be their way out. From where they are in the pit, they will fly towards the daylight which is at the end of the pipe. To prevent them getting out and potentially spreading harmful bacteria the fine wire mesh is placed at the end of the pipe trapping and eventually killing them.

OTHER DISPOSAL METHODS

Other sewage and waste disposal methods apart from pit latrine include septic tanks and soak-aways which were described in this series in the Searchlight Newspaper of December 8, 2006.

In addition tile field and absorption fields may be used by those people with adequate land space. It will involve trenching laying rabacca material, and perforated PVC piping.

In larger buildings, treatment plants ranging from a simple rudimentary design to complex primary and secondary treatment processes can be used.

Further information and guidance can be obtained from the Environmental Health Division.