Construction World September 2015

ENVIRONMENT

Boost to metro’s FRESH WATER SUPPLY

An innovative system to utilise return effluent from the Cape Recife Waste Water Treatment Works (WWTW), designed by leading local firm, AfriCoast Consulting Engineers, will significantly increase the water available for industrial and irrigation use – and, in turn, reduce demand on Port Elizabeth’s precious fresh water supply.

hole water used to irrigate the beachfront gardens and sports fields within economically viable reach. The concept was initiated with the NMBM Parks Department and Beach Managers. The beachfront, Port Elizabeth’s primary tourist attraction, currently uses potable water in flower beds but the grassed areas are not irrigated, leaving them less appealing than they could be. Increased demand Van de Merwe said a lack of funding and other priorities had slowed the project, which was initially designed and proposed by AfriCoast in 2006 and again re-examined in 2011, however work on the Return Effluent Scheme was now being implemented in parallel with the expansion of the Cape Recife WWTW. He said approval for the proposal, as well as the environmental impact assessment, was expected to be obtained by the first half of 2016, with construction taking approximately one year. “Water supply is a critical priority for the municipality and its stakeholders. There is increased demand on the available water sources due to expansion and densification of areas within the metropolitan area. “If all goes according to plan, returned irrigation water should be available to consumers by 2018,” he said. “The beach- front, golf course, schools and NMMU will benefit through the availability of irrigation water from return effluent at a substantially reduced price than that of potable water. “An existing return effluent scheme has been supplying the NMMU North and South Campuses and the Humewood Golf Course with irrigation water since the early eighties. The water is extracted from the primary holding pond at the treatment works and pumped up to supply reservoirs and ponds at the university and the golf course via metered connections,” said Van de Merwe. “However, the system is over 30 years old and in very bad shape. It will eventually be abandoned and replaced with the more comprehensive and sustainable proposed Cape Recife Return Effluent Scheme.” Port Elizabeth-based AfriCoast is a national leader in the field of water sanitation engineering and is the lead consultant for the return effluent scheme between the Fish Water Flats WWTW and the Coega Indus- trial Development Zone (IDZ). The firm also recently made headlines as lead engineering consultancy for the multimillion Nooitgedacht WTW project, which recently received finan- cial input from government in its promise to provide a long term fresh water solution for the Nelson Mandela Bay area.

of treated effluent of around 9 megalitres to a daily average of 18 megalitres, effectively meeting the demand for reclaimed irrigation water,” he said. “Currently, gardens and sports fields across the city are being irrigated with expen- sive, potable (drinking) water – an invaluable resource in the water-scarce Nelson Mandela Bay Metropolitan area. Borehole water is used to augment the supply of irrigation water, but that has negative environmental outcomes, including lowering the water table. “Yet in the meantime, thousands of litres of useable, treated effluent are being discharged every day through a wetland system and into the ocean, in the vicinity of the Noordhoek Lighthouse.” The Cape Recife Return Effluent Scheme aims to utilise this currently wasted return effluent in lieu of the potable and bore-

Return effluent is treated, purified sewage water that, instead of being released back into nature or the ocean, is returned for industrial

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utilisation, irrigation and other uses. The water quality conforms to standards set by the Department of Water Affairs. AfriCoast Consulting Engineers project manager Gerrie van de Merwe said the firm’s professional responsibilities, aside from construction monitoring and project management, include “the physical designs of the pump station, rising main, balancing reservoir, gravity irrigation feeder pipeline, irrigation reticulation systems and measure- ment of usage. “Cape Recife WWTW’s upgrade is currently under design. Once completed, the capacity of the treatment works will increase from a current maximum daily production

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The Cape Recife WWTW holding pond.

CONSTRUCTION WORLD SEPTEMBER 2015 ST TIO W L SE TE E 2015