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City invests in bettering the health of Milnerton Lagoon through short-term interventions and upgrade of Potsdam WWTW

The City’s Water and Sanitation Directorate is implementing ongoing remedial work at Potsdam Wastewater Treatment Works (WWTW) that will result in treating effluent received from homes, businesses and industry to a better quality. The City has also implemented short-term interventions in the Milnerton Lagoon to address diffuse sources of pollution.

Implemented short-term interventions

The Lower Diep River, including the Milnerton Lagoon, is in a poor ecological state due to diffuse sources of pollution. The City has identified and implemented critical short-term interventions that address the quantity of pollution entering the system.

The Directorate has sandbagged the Erica Road Outfall, creating a barrier between the pollution and the lagoon. The sandbags benefit the entire system by limiting lagoon water being pumped to Potsdam that Is functioning at capacity and protecting the lagoon from untreated sewage. This is a temporary solution and the impact thereof will still need to be established. The City has also conducted a high level feasibility assessment of implementing a low flow diversion which will potentially do away with the need for pumping at Erica Road Outlet.

The City is installing litter traps on identified stormwater outfalls that will capture solid waste before it enters the natural system. The litter traps will catch solid waste that enters the stormwater channels from Milnerton, Royal Ascott, Joe Slovo, and Phoenix.

Potsdam Remedial Work

Wastewater Treatment Works (WWTWs) like Potsdam have an important function to ensure that wastewater from homes, businesses and industries is treated optimally to be released as  effluent into the environment via our waterways for reuse purposes.

Since 2019, these are some key infrastructure investments that have taken place:

Refurbishing primary settlement tanks (PSTs):

Refurbished PSTs will reduce the loads to the bioreactor more efficiently and will greatly impact the effluent quality positively.

08 Plant’s PSTs:

By the end of last week, the last of three PSTs was commissioned. Refurbishments included concrete structure repairs, replacing bottom and top scraper rubbers, replacing the greasing system, stilling wells, scumbox, and centre bearings.

97 Plant’s PSTs:

Currently, both PSTs at this Plant are operational. One PST has already been refurbished, and the plan is to renovate the other in December 2022.

Containing wall built around Reed Bed No. 1:

This helps to increase the capacity of the reed bed, which assists with retaining any spills and overflows within the system, allowing the City to pump wastewater back into the treatment process. It also prevents contaminated flow from entering the Theo Marais canal via the reed beds.

97 Plant’s Settled Sewage Sump Refurbishment

This sump was recently commissioned after it was repaired and refurbished.

This sump houses four pumps that pump sewage through the 97 Plant. Over the years, because the concrete had deteriorated, stones and pieces of concrete entered the pumps and caused major damages, which resulted in not enough sewage being pumped to the 97 Plant, which caused hydraulically overloading of the 08 Plant.

The refurbishment and repairs allow more sewage to be sent to the 97 Plant and ease the hydraulic load on the 08 Plant.

Various Plant Infrastructures Maintenance and Repairs:

The City has started a process to repair and paint various roads, buildings and infrastructure to ensure the Plant complies with Health and Safety requirements according to legislation to provide a safe working environment for staff, stakeholders and visitors.

‘Potsdam WWTW is an old facility that we are steadily working towards an upgrade. We have placed Potsdam on the Mayoral Priority Programme, and the City closely monitors Potsdam WWTW’s operations.

‘Our operational team progressively attends to the maintenance and refurbishing of the older infrastructure and equipment. This is, in addition, to gradually adding new technology and upgrading plant capacity between now and 2026,’ said Councillor Siseko Mbandezi, acting Mayoral Committee Member for Water and Sanitation. 

Potsdam Upgrade

Potsdam WWTW is benefiting from a  R5-billion capacity upgrade from treating 47 million litres of wastewater per day to 100 million litres per day.

The City is currently upgrading the Potsdam WWTW to increase its capacity to accommodate the urban growth in the area. Cutting-edge membrane technology is also being added to ensure high wastewater treatment standards.

Potsdam WWTW falls within the Diep River catchment. This is one of the largest catchments in the city at over 1 500 km2 in size, half of which falls outside of the metro boundaries in the Swartland.

The Phase 1 demolition on the property is already complete. The project is currently at the end of the procurement phase, with mechanical and civil tenders awarded to contractors subject to a 21-day appeal period, the Section 33 process being completed and Council budget approval.

A Section 33 process is required for projects exceeding three years, including a public participation process. It will require Council approval before entering into a contract with a service provider.

Currently, the project is split into two components:

1.    Mechanical and electrical tender:

This tender is for the design, supply, installation and commissioning of mechanical and electrical infrastructure to upgrade and expand Potsdam WWTW.

2.    Civil tender:

This tender is for the civil construction of infrastructure and buildings to upgrade and expand Potsdam WWTW, including demolition works.

The City’s Bid Adjudication Committee has approved the award of both the civil and mechanical and electrical tenders for the Potsdam upgrade subject to the completion of a Section 33 process (construction greater than a three-year period) and Council budget approvals.

Community meeting

The public is invited to attend the second quarterly meeting, where the City will provide an update on the condition of Milnerton Lagoon and current interventions to help improve its water quality.

Details:

Date:    Wednesday, 30 November 2022

Time:    18:30 to 21:00

Venue: Leibrand van Niekerk Community Hall in Table View

Should there be any changes to these details, this will be communicated.

Source: City Of Cape Town

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