Our environment

by John
(Harare)

What we need in Zimbabwe are qualified environmentalists, there are many with opinion but based on nothing.

We encourage more and more dams for hydro-power which reduce the area for game, there are little or no laws regulating what we do on the shores causing erosion and eventual flooding - yet so many with unreasoned opinion when someone comes up with a project which has it all, stops the flooding in Mozambique and also promotes development in an eco friendly way in line with vegetation and animal life.

Comments for Our environment

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Apr 08, 2014

continued
by: John

Recently, Karibs Dam has been once again in the news.
A late friend of mine Prof Harlen Wwho was at the time CEO of zesa, and on the world utilities committee spoke with me on Kariba. The investigations team abandoned the idea of increasing capacity atb the dam by the addition of more generators as it was far too dangerous.
He was also concerned as was I wity the siltation which was causing strain in the dam wall and eccessive wear on the turbines and asked me to design a method of removing same which I did.
Zambexzi River Authority state that the dam needs to be maintained and repaired!
Zesa have decided that the Chinese expand the hydro station.
I have asked for an appointment with the Minister on the subject who has I believe been misinformed.
1. As a designer of patented equipment that manufactured concrete to an indestructible standard tested by CSIR in Pretoria the advice of ZRA is very suspect.
First concrete does not decay over years it gets harder thus their comment that the dam is 50 years old and needs maintenance is rubbish, - concrete cannot be maintained - the bunkers in Germany were so hard drills failed to work when they tried to remove them. When it cracks you replace it as is always done in the construction industry. A crack in concrete generally means that the mixture was wrong.
There is also incredible weight of siltation against the wall and friable rock supporting the dam. To give an indication of the siltation in the Zambezi a recent calculation from Tete to the coast where it currently floods calculated 50 million tons of silt needs to be removed.
The short answer is that the dam should have been built on friable rock either as friable rock unlike concrete gets more friable with age.
The solution is to disregard the opinion of ZRA and get real engineers in from overseas as there is a very dangerous situation .
The erosion cause by the spillway is of very minor importance as concrete, even a layman knows is used to support parkades and skyscrapers and thus is capable of suspending in space without cracking. Additionally claiming concrete needs maintenance is a joke as they suggest we should take all concrete structures to pieces all over the world for periodic maintenance - ridiculous!
Solution is and im confident that experienced surveyors and engineers from overseas will agree is either to drain the dam and dismantle to current dam wall and rebuild same in a stronger location or use the funds to build a large thermal power station releasing more land for game agriculture and minerals.
Whatever is decided, we need the advice of real engineers urgently as if there be a slight earth tremor or unnecessary vibration from expansion or spurious attempts to reinvent the wheel there will be a disaster which I believe will take out Cabora Bassa as well.

Jan 01, 2016

MEANWHILE
by: Bruce Crofts

Hi, John (Harare) I was on site at Kariba, early 1956. At that
time all that had been done was a dirt road from MAKUTI
to the Dam Site. Nothing on the North Bank. The diversion
tunnel was under construction. The Suspension Bridge was
already built. Road Bridge underway. Cementation were and IMPRESIT were working on the North Bank Coffer Dam.
I was not concerned with the DAM. I was employed by a
Salisbury firm of Quantity Surveyors - C.S Parsons & Ptnrs
who were retained by Richard Costain (Afrca) who had been awarded the C3 Contract to Build the Kariba Township over 5 Hills high above the Damsite. I am a Builder's Surveyor responsible for a profitable Final A/C
Costain were happy to assist Imprest who as Civil Engrs were pleased to have Builders close at hand.I was on site for 2Yrs 6 Months full time. I saw progress on a daily basis. I am not an Engineer.
This was a fantastic Project, English Engrs, Alexander
Gibbs & Ptnrs. Top Italian Construction Copany.
I am positively sure, that if the Dam was in any danger
of " Failing " Right now, as I type - a second Dam Wall
would be under Construction some 5 or 10 Miles down
the Gorge to protect the lives of all those who live down
stream. BC.

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