A ‘dam’ shame – Lake of Doom desperately needs remidiation

This is according to Rod Genricks, director of Turncard Trading, who specialises in the remediation of lakes and ponds.

His proposal on how to remediate the lake carries the backing of the Boksburg Lake Forum, which has been struggling for years to find a suitable solution to bring the lake back to its glory days.

The Advertiser recently reported that any mediation work on the lake by the metro has been halted, as an Environmental Impact Assessment report is not available, red-taping any sort of action.

However, according to Boksburg Lake Forum executive committee member Derek Fox, the problem is that the metro cannot use the expensive dredging machine to remove all the sludge from the lake, because the water is toxic.

“There is now a solution, which comes in the form of Genricks’ proposal. This will allow the lake’s toxic water to be properly treated before the dredging machine can be deployed to remove the sludge.

“However, action needs to be taken soon, since the summer rains are coming, which stirs up the sludge at the bottom of the lake that will bring the terrible odour to the fore.”

According to Genricks, the treatment of using Eco Tabs will cost the metro around R4-m. Once this has been done, the metro can then start removing the excessive sand, possibly relocate it to form an island in the middle of the dam.

“We have two problems in Boksburg. One is the excessive sewage that is pouring into the water because of a sewerage plant running beyond its capacity, and secondly, the sand that has been deposited into the water over the years because of mining.

“To treat the dam demands a two-fold approach: One is treating the water, and the other is to remove the silt and sand.”

The Advertiser has over the last couple of years written numerous articles on proposed treatments of the lake, featuring proposals, among many others, to build a silt trap. So far, not much has happened.

Genricks says that a silt trap will not help, as the damage has already been done.

“The state of our water in general in this country is a huge cause of concern. Let us take, for example, at our sewerage plants, which is being overloaded in terms of work, because of a lack of upgrade.

“What happens is that any sewerage plant over time needs to process more raw sewage because of growing housing and business developments. In the scenario, for example, in Boksburg, the sewerage plant is a running beyond its capacity, so it is pumping polluted water back into the streams and rivers.

“This has a knock-on effect, because rivers are connected. As rivers connect, the pollution is spreading, and further impacting crops.

“We even have video footage of people from the informal settlements washing vegetables in such water, only to be sold later.

“We are facing a major crisis, because polluted water is a breeding ground for superbugs, and it has dire consequences on our health and well-being.

“There are, however, means and ways of dealing with toxic and polluted water. Chlorine is also not the answer, because it doesn’t deal with the E-coli problem.”

Genricks has spearheaded numerous projects where a toxic or severely polluted body of water has undergone a successful remediation process. This includes, for example, Bruma.

“We had a case where a body of water was so foul it was basically battery water. You could not even walk into the water, because it will eat your shoes. We had to build ramps, and use a helicopter and a hover craft to take water samples.

“We treated the water, and within a month, the PH levels and oxygen levels were restored, resulting in vegetation growing once again around the water.

“With the right approach and the right support, bodies of water that are critical can be brought back to life, which is also the case with the Boksburg lake.

“I firmly believe any remediation process requires a balanced approach, such as ensuring that any existing wetlands remain in tact.

“Once the Boksburg Lake is remediated, it will not cost a lot to maintanance. If we treat this lake properly, then complete restoration of the phosphate cycle of the dam will occur within three months.”

Fox says that it is critical to get the lake back to its former glory days, in order to draw tourism.

“We are still trying to get the African Village of the ground, but what will it help if the lake is in such a mess. Again, why did they build the boathouse when the lake needs urgent attention?”

Fox feels that Genricks’ proposal is the best option.

“However, for this to work, it will take private funding. And this is what we are looking for – companies who are willing to come on board to support us in this remediation process.”

Genricks’ overview and proposed interventions for the lake:

Boksburg Lake covers an area of approximately 13 hectares in extent and approximately 3m in depth. This area has been steadily filled with contaminants including silt, heavy metals, raw sewage and other organic and inorganic material over a period of years.

The sludge is clearly anaerobic in nature, which is indicative of the odours being released from the sludge. This in itself is indicative of a low dissolved oxygen (DO) level and turbidity levels, while the dam is bordering on turning totally eutrophic. Coupled with this there is an evidently high-level of pathogens including E-coli.

Algae is a clear indication of high Nitrate and particularly Phosphate levels.

Without going into the source of the pollutants, which are clearly from upstream spillages and releases the impact downstream, is also worrying and needs to be addressed as well.

Many interventions have been discussed, all of which have basically been of a mechanical nature, which includes the use of a dredger to pump the sludge into holding ponds from where it can be dried and removed.

The problem with the sludge is toxic in nature, and an EMI would have to be done before any intervention could take place, and then a suitable dumping site would need to be found.

We know that as in the case of Bruma Lake, this was not a viable option, as no one was prepared to accept the sludge.

* Eco-Tabs

In order to overcome the above problems, we propose that an application of Eco Tabs and shock would reduce the sludge to an extent that the silt volume could be ascertained, and this could then be pumped into the centre of the lake, making small islands out of the now clean silt.

All smells could be neutralised immediately, as the application of oxygen into the base of the sludge achieves this very effectively.

This operation would mean that the treatment could begin immediately, as no EMI is required in order to remove the sludge. The pathogens and heavy metals will be dealt with, meaning the silt removal can be done at a substantially lower cost.

* Remediation

An application of a combination of Eco Shock and Eco tabs to the dam will achieve the following:

* Super saturation of the water with oxygen, evidence of this will be seen immediately through fish activity.

* Remediation of the sludge, as sludge will initially be forced from the bottom, rising to the surface.

*Immediate odour reduction such as control of H2S and NH3, including complete elimination of unpleasant odours (oxidation of reduced sulphur species and elimination of ammonia produced under anaerobic conditions).

* Mass reduction in anaerobic bacterial activity.

* Significant nutrient reduction (Phosphates).

* Mass increase in anaerobic bacterial activity and other microbial activity.

* Reduction in Algae firstly through removal of food source, secondly through removal of the algal bio-layer leaving the algae susceptible to bacteria.

* Water will start to clear as the sludge is digested.

* Reduction in the amount of organic matter such as animal waste and sewage (suspended and dissolved solids).

* Enhanced aerobic microbial degradation of organic matter leading to reduction in Chemical Oxygen Demand (COD) and toxicity.

* Reduction in anaerobic bacteria, thus preventing anaerobic degradation of organic matter and avoiding purification.

* Immobilisation of heavy metals.

* Oxidation of inorganic matter such as nitrites and sulphides.

*Better pH control (alkalinity prevents accumulation of organic acids and carbon dioxide and reacts with other anions in water).

* Sediment is maintained in an oxidised state just below the surface throughout all the seasons, which prevent dangerously low dissolved oxygen in bottom water when sediment is disturbed.

* Reduced foaming caused by Nocardia, Cyanobacteria and other filamentous microorganisms.

* Detoxifies cyanide and a number of other toxins in the water column sediment.