Construction World

CONSTRUCTION WORLD

SEPTEMBER

2015

ENVIRONMENT

Return effluent is treated, purified

sewage water that, instead of being

released back into nature or the

ocean, is returned for industrial

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

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-

Boost to metro’s

FRESH WATER SUPPLY

An innovative system to utilise return effluent from the

Cape Recife Waste Water Treatment Works (WWTW),

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.

The Cape Recife WWTW holding pond.

ST TIO W L

SE TE E

2015