Every two years, the Institute of Municipal Engineering of Southern Africa (IMESA) invites local, provincial and government or semi-government authorities and their engineering consultants to submit entries for the IMESA Biennial Project Excellence Awards. This year, the awards were held on 28 October in conjunction with the 78^th IMESA Conference at the Durban ICC Arena

Two projects in which engineering consulting firm Aurecon was involved walked away with coveted awards at the ceremony.

The first of these was Preekstoel Water Treatment Works (WTW) for the Water and Wastewater category, while Wolwedans Human Settlement Development was announced winner of the Community Upliftment category.

“The success of these challenging projects reflects the impressive commitment and determination of the municipalities involved,” commented  Aurecon South Africa’s managing director, Albert Geldenhuys.

More about Preekstoel WTW

Having experienced its most severe drought during September 2010 and April 2012, the catchment area of the De Bos Dam, which is the main water source for the Greater Hermanus area, was holding below capacity. In fact, the dam content had dropped to below 18% of its full supply capacity by May 2012.

In response the Overstrand Municipality in the Western Cape developed a series of groundwater well fields to supplement the surface water being sourced from De Bos Dam. But, the groundwater being pumped has high concentrations of iron and manganese, which must be removed. Problems associated with high concentrations of these minerals in potable supply range from aesthetic affects on tap water, fabric stains and water distribution networks being clogged with thick biofilm, caused by microorganisms that use iron and manganese in their metabolism. (Biofilm is present to some degree within most reticulation systems and their are even variants which form on the enamel of living organism’s teeth)

Given that the groundwater will in future make up a substantial portion of the total quantity of water treated at Preekstoel WTW, and since the groundwater scheme has been expanded to cater for the growing demand of the Greater Hermanus area, especially during peak holiday periods, it became necessary for the treatment of the various well fields to be integrated and upgraded to ensure reliable achievement of target water quality. As a result, a new project was implemented to up the water supply and treatment capacity of the Preekstoel WTW. Aurecon was appointed to provide water and wastewater treatment services for this important upgrade project.

To contend with metals in borehle water, a biological plant was built next door to the existing plant at the Preekstoel WTW for treating a maximum of 10 meglitres per day. After an extensive period of monitoring and optimising, plant cultures had established sufficiently to deliver treated water meeting the SANS 241:2011 quality requirements of the build.

Aurecon commended the Overstrand Municipality “for providing a cost effective and innovative means of securing the Greater Hermanus water supply requirements, as well as protecting the area against future droughts.”