Lydenburg Outfall Sewer

The Lydenburg outfall sewer consist of the introduction of a new outfall sewer for the proposed future developments in Lydenburg. The expected high rate of residential development earmarked for Lydenburg in the near future has resulted in the urgent upgrading of all water and sanitation infrastructure in order to accommodate any future development.  The Lydenburg outfall sewer include the following infrastructure:



•    The new outfall sewer (500ND) from the upstream end of the new Lydenburg Extension 6 up to the position of the existing Mashishing sewer pump station.
•    A new sewer pump main crossing the Dorp River.
•    A steel bridge structure over the Dorp River
•    A 2575m long concrete or HDPE outfall sewer pipe that follows the route of the existing Lydenburg outfall sewer. The diameter varies from 525mm to 750mm.

DETAILS OF THE WORKS

The sewer outfall system consist of three sections. An upper gravity section from the source to the new sewer pump station. The second portion being the sewer pump station and the sewer pump main across the Dorp River. The third section being a  gravity main from the pump main pressure break to the existing Lydenburg sewage treatment plant.

Upper sewer outfall section:

The outfall sewer commences at the upstream end of the currently developed Lydenburg Extension 6 and terminates at the new sewer pump station. The sewer gradient is rather flat and a large diameter sewer is introduced in order to accommodate all the flow generated by the future developments upstream of Lydenburg extension 6. The design peak wet weather flow for the outfall sewer section is 512l/s. This is a very large volume and needs to be accommodated in a large diameter pipe. The outfall sewer consist of a 525mm diameter concrete pipe.

Sewer Pump station:

The existing sewer pump infrastructure consist of a newly refurbished sump structure with 2 x Gorman Rupp pumps which pump sewage through a 150mm diameter steel pipeline across the Dorp River to a sewer manhole located on the Corner of Potgieter and Voortrekker streets. The current sewer flows contributing to the existing sewer pump station duty point are approx 10l/s. This existing sewer pump station will become redundant and the new sewer pump station currently under construction will accommodate the flows generated by the existing townships.
The new sewer pump station consist of the following:

•    Cabling and switchgear for all 4 Gorman Rupp T10 pumps (3 duty + 1 standby). All Pump control and safety measures.
•    2 x Gorman Rupp T10 pumps (1 duty + 1 standby), a flow of 137 l/s is achieved. These pumps must be running at 1050
     rpm and be supplied with 55 kW motors and switchgear. The pumps only require 37 kW motors at this stage, but the final
     requirements dictate the 55 kW motors. Pump and motor pulleys are used to determine the revolutions and by supplying
     the pumps with the larger motors mean that only the pulleys need to be replaced in order to achieve the higher duty point at a later stage.
•    The complete pump manifold inside the pumping station is also to be provided. Future pumps can then only connect onto it
     and the connecting pipe work gets supplied with each pump.
•    Installing an additional Gorman Rupp T10 pump running at 1150 rpm. Again, the pump is supplied with a 55kW motor although it now only requires a 45 kW motor.
•    Changes the pulleys on the existing duty and standby pump in order to run the pumps at 1150 rpm in order to achieves a flow of 320 l/s.
•    Connecting pipe work, including specials, for the above pump to connect onto the existing delivery manifold and suction special cast into the pump station wall.
•    Installing an additional Gorman Rupp T10 pump running at 1,250 rpm. The pump is supplied with and requires a 55kW motor.
•    Changes the pulleys on the existing duty and standby pumps in order to run the pumps at 1250 rpm achieving a flow of 495 l/s.
•    Connecting pipe work, including specials, for the above pump to connect onto the existing delivery manifold and suction special cast into the pump station wall.
•    The sump now provides 2 hours storage at ADWF for the above pumping capacity. Again adding the 28 l/s of the T6’s, the resulting pumping capacity is now
      28+495=523 l/s.

Lower sewer outfall section:

The 2,575m long, 525mm / 750mm gravity outfall sewer from the pressure break sump in Potgieter Street to the Sewage Treatment Plant. This sewer has 2 stream crossing. The pipe configuration at these locations consist of 500mm and 750mm diameter steel (coated and mortar lined) pipe respectively placed on reinforced concrete pedestals at these locations. The gravity portion of the sewer has two minor road crossings and one major road crossing.


Additional Info

  • Province: Mpumalanga
  • City or Town: Thaba Chweu
  • Project Date: 2008 to 2009
  • Project Value: R 19 000 000
  • Client Name: Mpumalanga Housing Finance Corporation
Last modified on Wednesday, 20 November 2013 08:38
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