- After numerous complaints about the return of the stench at the Milnerton Lagoon, the City of Cape Town says there have been approximately 11 collapses on the existing 900 mm diameter fibre cement sewer pipeline on Montague Drive since 21 August.
- On 17 December, environmentalist Caroline Marx posted video footage and photos of raw sewage overflows pouring into the Diep River and Milnerton Lagoon via the Theo Marais canal – 23 days after a predirective was issued against the City ordering them to stop.
- Residents claim these huge overflows of raw sewage into the Table Bay Nature Reserve are continuing daily, resulting in a foul stench causing adverse health symptoms in nearby residents.
After numerous complaints about the return of the stench at the Milnerton Lagoon, the City of Cape Town says there have been approximately 11 collapses on the existing 900 mm diameter fibre cement sewer pipeline on Montague Drive since 21 August.
“These are all at various stages of repair.
“This is due to ageing infrastructure (of approximately 50 years old), as well as excessive sewer flows from stormwater ingress as well as sand ingress which results in the sewer operating under pressurised conditions,” says Zahid Badroodien, Mayco member for water and sanitation.
“Residents will be aware of the recurring discharge emanating from the Koeberg Pump Station emergency discharge point,” he adds.
Badroodien assured the community that an additional 10-inch pump is on site and will be used to alleviate the pressure on the network.
“The pump is planned to be used to support the increased capacity to pump via an additional temporary rising main to Potsdam from PS. Unfortunately, the line has been vandalized and quotes are being obtained to repair the line,” he says.
Raw sewage
On 17 December, environmentalist Caroline Marx posted video footage and photos of raw sewage overflows pouring into the Diep River and Milnerton Lagoon via the Theo Marais canal – 23 days after a predirective was issued against the City ordering them to stop, she says.
“Following an inspection and investigation by the Western Cape Department of Environment aka the Green Scorpions in November during which raw sewage was again observed overflowing into the Diep River from the Koeberg Road sewage pump station, a predirective was issued against the City on 24 November instructing them to provide an action plan to prevent these overflows within seven days,” she says.
Marx adds that these huge overflows of raw sewage into the Table Bay Nature Reserve are continuing daily, resulting in a foul stench causing adverse health symptoms in nearby residents “and yet again devastating the previously recovering Diep River/ Milnerton Lagoon estuary ecosystem”.
“While problems caused by the sewer line collapses in Montague Gardens are acknowledged, the need to upgrade this line was identified in 2011 and the possibility of excess sand entering the line and damaging pumps was foreseeable.
“The need for a temporary overflow pond at Koeberg Road sewage pumpstation was identified in 2020. The City has had over two months to take effective emergency action since the overflows started in October but has failed,” she says.
Badroodien says in the beginning of November an existing sewer pipeline was damaged during the construction (trenchless micro-tunnelling) of the new bulk sewer pipeline, which is being installed between the Theo Marais Canal and Koeberg Road.
“Damage to the sewer pipeline resulted in sewage seeping into the canal, and impacting on the tunnelling operation.
“As such, the contractor blocked the damaged sewer pipeline in an upgradient manhole on the eastern side of Koeberg Road.
“This resulted in the sewage overflowing into an adjacent stormwater manhole leading to the canal.
“Unfortunately it does not appear possible to bypass the damaged sewer line, or install a layflat pipeline across Koeberg Road due to the high traffic volumes,” he says.
Short to medium term plan
Badroodien says the City has plans for repairs:
- Water Pollution Control Teams activated and on site;
- Pump Station Team on site attending to any necessary repairs that can be undertaken;
- At the collapses of the Montague Bulk Sewer line over pumping with mobile pumps is underway;
- Repairs of the collapses are ongoing. The pipeline is deep at an average depth of around 5 m, which together with the high water flows complicates the repairs thereof;
- A temporary berm has been constructed in the canal in close proximity to the Montague Bulk Sewer Collapse to contain sewer flows and enable the contaminated water to be pumped, via a mobile pump, into a sewer manhole leading to the Koeberg Road Sewer Pump Station.
Long term plan, investments
- Koeberg Pump Station Upgrade which includes emergency discharge pond as well as sand trap and the
- R470 million Milnerton Bulk Sewer upgrade.
“Residents say when effluent levels are low the pump station is able to cope.
“However, at peak times when levels are high pumps are not able to cope with the high volumes due to the impact of sand ingress on our pumps. Please do consider reducing flush frequency, taking shorter showers as well as reducing sources of other grey water,” Badroodien says.
