City's water recycling crippled

More than a week after the heavy fuel oil spill at Namibia Dairies, which halted Windhoek's water recycling, there is still no reclamation of water taking place.

This has resulted in NamWater having to produce the daily shortfall of 18 000 cubic metres of potable water which is usually produced by the Windhoek Goreangab Operating Company (WINGOC).

Experts have further said that it could cost more than N$30 million for the rehabilitation and clean-up of the city's sewage reticulation system.

Goreangab Dam is currently taking between 24 000 and 27 000 cubic metres of raw sewage daily.

Providing an update on the spill that occurred at the Namibia Dairies plant in Avis on 3 February, the CEO of the City of Windhoek, Robert Kahimise, said the incident resulted in the shutdown of both the Gammams Water Treatment Plant and as the Goreangab Water Reclamation Plant that is operated by WINGOC.

“This means there is no reclamation of water taking place currently as a result of the incident.”

Kahimise explained that the manufacturing processes at Namibia Dairies require high levels of hygiene and sterilised equipment. Boilers are used to heat water which is used not only for sterilisation, but also to pasteurise milk.

The boilers are fuelled with heavy furnace oil (HFO), a crude oil which is supplied by Engen Namibia. This crude oil is contained in a 24 000-litre steel reservoir at Namibia Dairies.

Kahimise said HFO has a relatively low density and needs to be heated and circulated continually, even during the time that the plant is not operational.

“The heating of HFO is an automated process and needs no supervision.”





According to him a safety valve malfunctioned during the early morning hours of 3 February and caused a rupture in the pipeline supplying HFO to the boilers.

The entire 24 000 litres of HFO spilled through drainage holes in the boiler room and into oil traps on site, where most of it could be contained, but an estimated 6 000 litres eventually spilled into the sewerage system.

Namibia Dairies discovered the spill on the morning of 3 February and immediately informed the City's pollution control section, after which the Gammams Waste Water Treatment Plant was immediately shut down.

All influent was diverted from the intake of the treatment process and spilled into an open area at Gammams.

Kahimise said oil-contaminated influent flooded the lower-lying areas of the Gammams plant and eventually found its way into the Goreangab Dam.

“Some of the contaminated influent progressed into the primary settlers of the plant before it was shut down.”

WINGOC was also informed about the shutdown at Gammams and had to shut down their water reclamation processes the same day.

“The shutdown of both plants was crucial as a precaution not to pollute biological processes required to produce potable water,” said Kahimise.

Meanwhile, a joint response team consisting of officials from Namibia Dairies and the City was formed to strengthen the efforts to contain and clean up the oil spill and to provide the relevant support in the rehabilitation initiative.

Namibia Dairies also engaged experts who managed to clean and remove a total of 18 000 litres of HFO mixed with water from its site and this was safely disposed at the Kupferberg landfill site.

According to Kahimise an oil spill expert from South Africa did an assessment of the damage and proposed rehabilitation procedures in an attempt to reduce further pollution.

“Based on the assessment, a total of N$32 million was quoted for rehabilitation over a timeframe of two months, to clean the affected reticulation system.”

Kahimise said a second and third opinion will be sourced before a decision on this matter is taken.

He said with the Gammams Waste Water Plant out of action, no water is delivered to WINGOC for the reclamation of potable water.

According to him WINGOC produces 18 000 cubic metres of potable water daily and this shortfall is currently being supplied by NamWater.

The oil spill has also affected the operations of two contractors at Gammams.

These operators are Cape Advance Engineering, which produces electricity from digested sludge, and Biosolids, which uses dry digested sludge to produce fertiliser.

Fish in the maturing ponds at Gammams are dying because of the oil contamination and a lack of oxygen.

“People residing near or on the banks of Goreangab Dam are cautioned not to use the dam water for any reason,” said Kahimise.

He said incoming sewage, or influent, at Gammams was still spilling into the Goreangab Dam although the oil contamination has significantly reduced.

“It is believed that the entire sewage reticulation route from Namibia Dairies to Gammams is contaminated with HFO, as the oil attaches and penetrates cement surfaces.”

This means that traces of HFO will continue to wash off with sewage over time.

Kahimise said the treatment process may soon commence once the influent reaches a specific quality which is fit for treatment. This is being monitored daily by scientific services.

ELLANIE SMIT