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WONGI WATERHOLES JUNE INNUNDATION

 

The image above  is a google of Wongi Waterholes and Lenthalls dam, it clearly indicates what the normal water level of the holes should generally be , The image was taken by satelite in 2006 .

The  image above is a close up of the loop road and where the extraction pump has been set up , it clearly shows that the ‘natural’ water level for the wetlands is approximtely 70 mts from the loop rd .  

 

The images below were  taken  on friday June 6th at 12.06pm , they  clearly show that the water level on the waterholes side  of the loop rd , was level with the bottom of the white marker post . This equates to an unatural elevated level of approximate 1.4 mters .

 The natural drawdown rate ( or drainage) of these wetlands during a typical flood episode would be  ca 24hrs (this has been anecdotally confirmed by local long term residents) .

The IROL (Interim Resource Operations Liscense) granted to WBW from the Ministers department ( QNRW) states the following , ”

 

  

 

 

 

S2.6

Upon the raising of Lenthalls Dam, water is not to be backed up so as to cause flood

 

inundation of the Wongi Waterholes above the present levels experienced at the time of

granting the Licence.

Any structure, (including any embankments, gates, syphons or pumps) that is designed

to protect the Wongi waterholes from flooding by the raised dam full supply level is to

be operated in a manner that protects the Wongi Waterholes from prolonged flood

inundation.

When the drainage pipe at Loop Road is inundated so that the flood flap on the

downstream end of the drainage pipe is closed,

the level in the Wongi Waterholes must

be reduced until no more water drains into the pump well at Wongi Waterholes

(described in S1.4) at a rate consistent with the natural draw down rate that would have

existed prior to the raising of Lenthalls Dam.

The image below was taken on the 10 th of june , 4 days ( 96 hrs ) after the water was level with the white guide marker post .This indicates that after 6 days of pumping the level has only been reduced by ca 300mm .  It is believed that the extraction pump commenced ca the 4th june , which indicates that water level has remained artificially elevated  for ca 6-10 days , which has not ‘protected Wongi Waterholes from prolonged flood innundation” , as required under the IROL .

So we need to ask , ‘ is this a demonstration of ‘Best  Management Practise’ from a corporation which boasts of  having and implementing a  sustainable environmental water management mantra,  globally ?.

The evidence speaks for itself , you can only mimic a ‘natural drawdown rate’, if you can extract the water at the same volume of Megalitres per hour that would naturally occur , ( 24hrs ) without 2 metre crest gates .

The alternative is to ensure that the crest gates are lowered for sufficient time to ‘mimic’ the ‘natural drawdown rate ” .

 

 The evidence suggets that a ‘mimicking’  of drawdown rate  is not achievable if you will only allocate one pump , as a public relations excercise,   rather than a commitment to  abiding by the requirements of an operational license .

 FEB 2008 INNUNDATION

QNRW officers inspecting levels in Feb .

 FAILING, FAILING, OVER THE BURRUM WAVES!

 
 

 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

One comment

  1. EMAIL COPIES

    “Peter,

    RE:TOPS Gate Failure – likely inoperable when Water levels reached 26.69 in early June 08

    1. Is it possible for the calibration to be up or down from the level – indeed maybe water levels were higher?

    2. From What date would the calibration be out?

    3. We note in the early June event Wongi was topped over ( Wongi Water hole joined Wongi Flat) which indicates the water levels in Wongi Flat and the wider dam were at least RL26.5 probably higher – why were the gates not working? ( Remember we also have photos at the gate wall in june that will indicate height and provide an indication as to whether the calibration is accurate or not)

    3.1 How can you evidence that the calibration is actually out?

    3.2 How long do you claim the calibration has been inaccurate?

    Public Saftey is reliant on accurate reporting of the Dam and TOPS gates operational capacity ( or lack of it ) and of accurate reporting of water levels, if the dam supervisor cannot be trusted what evidence do you ask him to provide? Who is the third party?

    4. Incident reports – When we first contacted NRW we asked for a copy of the incident report written in FEB 08 – I recall the incident report was to be supplied in 72 Hours of the event – that is an incident report should have been generated around 29 January and again around 12 Febuary a third report would be generated for the June event. Would you please provide these three reports. ( I note they have not been included in the FOI documents)

    RESPONSE
    “Because the dam gate operations are not controlled by the BoM water level sensors, I am not willing to get involved in the accuracy of the ‘levels’ it produces at this stage. It is a reporting issue, and as such, is an issue for the BoM and possibly the dam owner (I am not sure how it is funded). It just depends on how often they update their calibrations etc. However, I am not totally surprised by the difference – it probably had not been ‘calibrated’ for some time. I know the errors can be either positive or negative. The main issue is knowing what the actual water level is … and that is typically the role of the dam supervisor.

    I am unaware as to why members of the public were not allowed access to the dam on 3/6/08. It may just be a case that they wish to control who goes onto their property from a public risk perspective. Again that is not an issue that I have any power to control.

    I am hoping to visit WBW towards the end of next week to discuss these uses with them and get a first hand look at the issues you have raised.

    Peter Allen
    Director Dam Safety (Water Supply)
    Water Industry Regulation
    Telephone 07 3224 7636, Mobile 0418 728 755 Facsimile 07 3224 7999
    Email peter.allen@nrw.qld.gov.au
    http://www.nrw.qld.gov.au



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