DESIGN : DEAR PLUMBERS
23
Rainwater and stormwater design
By
D . S ( Vollie ) Brink Pr . Eng . MSAICE , MPMISA
The practical experience of the plumber and even the architect and engineer about rainwater and stormwater seems to be very limited .
Rainwater and stormwater have serious legal implications if it was not correctly designed and correctly installed .
The Plumber ’ s theoretical knowledge and practical competence is basically the installation of prefabricated house gutters which have become outdated as it has become a ‘ provide-and-install ’ installation by a specialist who is not a plumber .
There is really no plumbing skill required anymore in the installation of house gutters and the plumber can use his \ her time better on real plumbing work .
The gutters available on the market also do not make provision for the various climatic areas and make gutters and down pipes to suit the rainfall of the areas , it is a ‘ onesize-fits-all ’.
There is also a gap when it comes to rainwater and stormwater design in the practical training of many buildings water systems . Instead , it is left to persons with no theoretical knowledge nor practical experience , who in many cases , use manufacturers to design the systems of large buildings for them .
Many developers also do not appoint geotechnical engineers , often with serious consequences later for the owners of the development .
One very large business complex , which has a river running through the building had serious problems . This building ’ s rainwater / stormwater was not designed by an engineer , and the owners experience constant serious water damage . Many developers are not aware that they have to provide stormwater retention facilities and failure to do so often ends up with serious repercussions and claims and costs .
Large roof areas require correct roof rainwater management systems design .
Roof rainwater systems and stormwater drainage management requires specialist competent engineers – mostly civil engineers .
Roof rainwater and the site stormwater systems must be addressed including with subsoil drainage and stormwater retention preferably all by one competent specialist engineer .
The stormwater / rainwater / subsoil drainage / rainwater retention of a development and buildings can cause serious legal implications and are often neglected by developers when the design is left to someone who is not competent .
I was recently asked by a plumber to help with advice on a complex where the subsoil water system and rainwater design and installation was done by a , shall I say ‘ someone ’ who is obviously not competent and it was a disaster to say the least . High retaining walls have collapsed , a makeshift subsoil system is in the wrong position and outlets made in the wrong positions cause serious damage during rain , causing flooding of the building where rainwater is running more than a metre high through the houses . This is not a problem it is a disaster , and not the work of a plumber .
Perhaps it would help to get a copy of the local by-laws of the responsible municipality and study it , then leave it to a competent engineer to do the design .
Don ’ t accept work for which you are not qualified , and not experienced nor competent to perform . PA
Kind regards ,
Vollie
Vollie Brink is one of the industry ’ s longest-serving wet services engineers . He continues to serve on SABS committees and has been involved in the Green Building Council ’ s Green Star rating system . Brink continues to consult for various organisations while enjoying a wellearned retirement .
“ Roof rainwater systems and
stormwater drainage management requires specialist competent engineers – mostly civil engineers .”
July 2021 Volume 27 I Number 5 www . plumbingafrica . co . za