16 DESIGN : DEAR PLUMBERS
Storm water must preferably not be pumped and must be designed to gravitate . Drainage pipes must be large enough to discharge storm water and materials that can cause blockages ; such pipes are usually 300mm diameter to 400mm diameter . Additionally , Catch-pits must also be large enough to prevent blockages and prevent rubble to cover the grid .
Where a property is the lower property and there are well placed weeping holes in the boundary wall to spread the storm water , then the owner of the lower property is not allowed to block these weeping holes . The owner of the lower situated property must accept the storm water from the higher situated property .
It is not worthwhile to take legal action to solve disputes , rather work together and solve the problems with competent engineering .
Storm water management / design solutions must be an integral part of the design of the building and its services and allow the owner ( s ) a lifelong peaceful occupation of the property and its services . If there is no municipal storm water connection for the property , then the storm water from the property must exit above ground level at a position as agreed with the local authority .
A storm water pipe which collects storm water must exit above ground level somewhere on the property or out of the property and the best and most cost-effective system is a system that is designed to gravitate . Pumped systems can be very expensive and are not always reliable and need back-up power and reliable maintenance .
• The calculations of a storm water system are critically important and require competence , experience , and correct assumptions .
• The rainfall of the specific area must be used for calculations and depending on the area , the design can be for 1:100 years and lately it can even be much more .
• Roof storm water / rainwater design is also critically important to be designed by a competent engineer and to have a safe building such as hospitals , old age homes , shopping centres and office buildings , etc .
• The costs to repair damage are usually more than an engineering design and installation . The design and installation must take into consideration climate change .
• Another important part of storm water is “ maintenance ”. If a storm water system is not maintained and regularly cleaned , and specifically before the rain season , then you can expect problems and damage , and even loss of life .
• Storm water management systems are not designed for , and cannot cope , with flooding .
• The design of a system must also consider hail as it can seriously block gutters , box gutters , parapet wall gutters and channels , etc .
• Large buildings and vulnerable buildings , etc ., must have provision for emergency communication and emergency services .
The design and installation of a storm water management system of a building is usually left to the last minute and in many cases is never provided and left as a saving , with dire consequences later for the body corporate or the new owner – this should be made an offence .
I have seen many buildings where the storm water was connected to the nearest sewer connection . The stormwater management system of specifically large buildings with large roofs should be a priority and need more attention by the building inspectorate .
I have come across many buildings with “ NO ” storm water system and serious consequences and damage for the owners . In most cases the original developers / owners have disappeared , drawings are not available and eventually become a costly problem for the body corporate . This also means that the building inspector approved the building for occupation without storm water system . PA
www . plumbingafrica . co . za @ plumbingonline @ plumbingonline @ PlumbingAfricaOnline August 2022 Volume 28 I Number 6