Midmar Water Treatment Plant Upgrade

Submitted for PPS - SAICE Project Awards 2020

Received a Commendation at CESA/AON Engineering Excellence Award for projects from R 50 to R 250 million

Employed a sizeable labor force from the local community

Challenges

All of this work had to be carried out with minimal disruption to the production of water and brought online without affecting the environmental compliance of the plant's discharge to the Umgeni River.
Managing a multi-disciplinary team of designers, contractors, and sub-contractors while meeting the client's wishes and changing requirements proved to be one of the most significant challenges faced by the consulting team.

Solutions

Upgrades to the chemical dosing system, an additional new super pulsator clarifier, and six new rapid gravity sand filters at the main water treatment works. A new backwash water recovery tank, two new clariflocculators, and a gravity thickener at the sludge treatment works with associated mechanical, electrical, control, and instrumentation upgrades and integration were also implemented.
Covered full multi-disciplinary design that included process, chemical, civil and structural, mechanical, and electrical control and instrumentation engineering, as well as overall responsibility for occupational health and safety, environmental monitoring, construction supervision, final testing, and commissioning of the plant.

Highlights

Increasing the capacity of the plant greatly improved the ability of the client to provide a valuable basic resource to a wider community.
The project was completed within the agreed time extensions.
Re-engineering of the design for the backwash plant outlet to the river. It was constructed from excavated rocks and boulders to ensure an aesthetic yet functional structure that blends into the surroundings as it is visible to the public from the other side of the river.

Project numbers

The Midmar WTP required upgrading from a design operating capacity of 250 ML/d on a raw water intake basis to a raw water intake of 395 ML/d, corresponding to a treated water production capacity of 375 ML/d.
The tendered price of the project was R 190,438,595.76 including contingencies and escalation, but excluding VAT.
During the course of construction, the client requested a number of fairly significant changes in scope that resulted in additional budget being allocated to the project. The project came in with a final construction cost of R 230,375,127.34.
The CPG value achieved by Icon was in excess of 41%.
Construction commenced in May 2015 and was completed by June 2019.
Extension of the existing chlorination building to house a new 28 ton chlorine isotainer tanker, with associated new wet scrubber designed to meet the requirements of the MHI assessment, weighbridge, and integration to existing chlorine dosing system and SCADA.
New 100 ML/day pulsator.
Six new rapid gravity sand filters
Two new 17.5 m diameter clariflocculators complete with associated pipework.
New 15.5 m diameter gravity thickener.
Upgrades to the power supply at the Mills Falls pumpstation
Replacement of three existing pumps and the addition of a new pump and motor (675kW) with VSD drive at the Midmar dam raw water pumpstation to accommodate the increased flow in two parallel pipelines (one new pipeline implemented by others).