Rimer's Creek Water Treatment Works

Project Status: Completed

Project Duration: 16 Months

Project Cost: R42M

ABOUT THIS PROJECT

This part of the Lowveld is better known for its rich gold and asbestos deposits, mine disasters and Jock of the Bushveld than infrastructure development. During 2014, following a lengthy political process, a decision was taken by government to amalgamate the then Mjindi Local Municipality, earlier known as Barberton, with the capital of Mpumalanga, Mbombela Municipality. As part of the amalgamation, a ‘wedding gift’ from government was funding for the refurbishment and upgrading of bulk water infrastructure to the residents who now seemingly transferred their political expectations to bigger concern at the capital.

One of the projects identified and prioritised was the refurbishment and upgrading of the Rimer’s Creek Water Treatment Works including the outlet works of the main raw water source, the Lomati Dam.

Following a lengthy procurement process for professional service providers our company was awarded the work as preferred service provider and work commenced in all earnest.

The Rimer’s Creek Water Treatment Works (WTW), situated in the Barberton Nature Reserve, approximately two kilometres south of Barberton in Mpumalanga, was upgraded to a level where it would be able to treat a sufficient amount of water for a future population of approximately 87 000 persons at the required drinking water standard, SANS 241. The treatment works serves the communities in Barberton and the surrounding area. The old works consisted of chemical dosing, up-flow filtration and disinfection facilities.

The project focussed on the upgrading of the WTW to a design capacity of 15 megalitres per day with the addition of a formalised chemical dosing facility, oxidation, sedimentation and sludge-handling processes and a supernatant and wash-water recycling facility.

The works that formed part of the project can be summarised as:

A new chemical dosing facility;
A cascade;
Two circular clarifiers;
Sludge drying beds;
Refurbishment of a filter;
Interconnecting pipework;
Formalisation of the stream and low-level river crossing;
Access road;
Refurbishment of Lomati Dam outlet works; and
Associated electrical works and telemetry.

The works receives its raw water from the Lomati Dam through an integrated gravitational system of outlet works, chambers, a tunnel, pipes and the creek. With only a chemical dosing and up-flow filtration processes, the water could not be treated to the required standard. Traces of iron and manganese were found in the raw water, which the current processes were unable to remove/treat. Due to the latter, processes such as oxidation in the form of a cascade and sedimentation in the form of circular clarifiers were proposed.

The capacity of the old works, when operating under perfect conditions, was sufficient. However, due to the recent droughts and lack of sludge treatment and recycling facilities, the filter backwash cycles had been neglected. Subsequently, the works could only operate at approximately 80% of its design capacity. Similarly, the raw water quality deteriorated because of the changing catchment characteristics of the Lomati Dam. The design capacity for the upgraded works were to remain at 15 megalitres per day.

With the works located inside the Barberton Nature Reserve adjacent the Rimer’s Creek, a lengthy environmental process was concluded with environmental authorisation granted as well as a water use licence. The environmental management programme was stringently enforced to ensure that minimal disruption and damage was caused during construction. The addition of the sludge-handling process further ensured that the ecological system downstream of the works can be restored to normal conditions.

The location of the works, due to some steep slopes and a stream dissecting the old and the extended works, proved to be challenging. The design team and contractor had to implement innovative ways to make the upgrade fit for purpose.

Various level platforms had to be created for infrastructure while ensuring that the hydraulics through the works remained unaffected.

The stream was formalised with the use of various gabion walls, weirs, a stilling basin and a low-level river crossing to protect the works in the event of heavy rains. Rock for the gabions was obtained by breaking larger boulders from excavations on site.

Old, unused slow sand filters were converted to sludge drying beds, thus ensuring that no sludge was being discharged into the stream.

Apart from the usual employment of local labour, local subcontractors were appointed to construct valve chambers and gabions under stringent training and supervision of the resident engineer and contracts manager.

The project was completed and successfully handed over to the employer during June 2019.

Acknowledgement

We are pleased to acknowledge contributions by the professional team in delivering the project successfully and save to the Municipalities expectations nl;

Peter Marota : Project Manager - Mbombela Municipality
Johan Jooste (Pr Eng.) : Project Manager - Department Water Sanitation
AD Watts (Pr Tech Eng.) : Project Manager - AFI Consult
Krynauw Coomans (Pr Tech Eng., PMP) : Design Technologist - AFI Consult
Oloff Bergh (Pr Eng., Pr CM) : Construction Manager - AFI Consult
Banie Lundie (Pr Tech Eng., Pr CPM) : Project and Construction Manager

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