66 / 72
DECEMBER • 2016
Construction
WORLD
64
The AfriSam Innovation Award for Sustainable Construction
E
REHABILITATION OF BRUMA LAKE
The key objectives of the remedial work were to address
community problems, in particular the bad odour and aesthetics
which characterised the lake. The remedial work aimed to reduce
the public health risks and to restore the aesthetics and amenity
of the area for the public and the surrounding business community.
Initial land-based surveys were conducted in an attempt to
quantify the amount of material that had ultimately silted up the
entire lake but these were found to be impractical. The contractor
employed the use of Lidar Survey, once draining the lake of surface
water, to gain a clearer picture of just how much silt had collected
over the years.
This technology also allowed for intermittent aerial
photography to judge progress over the duration of the project.
The contractor subsequently procured a drone-mounted camera
with which aerial photography and videography could be carried
out on an ad hoc basis.
Being a public space, the rehabilitation of Bruma Lake affected
both the social aspects of the area as well as public and private
business in the area and immediate surrounds.
The architectural design incorporated existing elements of
the lake and surrounds into the design of new elements with
natural rock components to soften the harsh look and feel existing
concrete basin and dam wall. Mounds and soft-rounded slopes
ensured attractive flowing greens inviting people into the public
space from outside.
Wetlands and hydraulics expert Chris Brooker (cba
Expert Engineers) executed the engineering design for the
Bruma is a 30 year-old suburb of Johannesburg,
South Africa. It is noted for a small (5 hectares)
man-made lake which, until the commencement
of this project, was being treated to reduce water-
borne pollution. The pedestrian bridge crossing
the original lake has also played an integral part in
facilitating ease of access to the business district,
recreational and retail facilities.
project and also acted as principal agent for the client.
The proposed river bed was intended to replace the existing
lake and the meticulous design was specified based on necessary
environmental factors and shear forces experienced during worst-
case conditions. The recovered silt was used for backfilling the
remainder of the lake basin to create a recreational park.
Immediately upstream the Queens Wetland area was
rehabilitated. Over and above the wetland rehabilitation, stringent
controls were put in place to monitor river conditions both
upstream and downstream. This enabled the environmental control
officer to determine the impact, if any, that the construction works
may have on the quality of water being released downstream.
The start of the project also saw the successful rescue of birds’
nests by the contractor with numerous eggs reportedly hatching at
a local conservancy.
Inoculation/prophylactic measures were taken for all persons
who entered the site due to the initial potential for exposure to
hazardous materials. This was a strict prerequisite to anyone who
wished to gain entry into the lake basin.
The in-situ soil was treated with limestone lime to aid in the
natural breakdown of hazardous inorganics as well as balance the
soil PH.
The main scope of the project was completed within time
(June 2015), save for the bridge works which were determined
to be greater than expected and therefore collected a separate
programme due to progressive design and adaptations as well as
long lead items, completing March 2016.
Through constant interaction between the contractor, principal
agent and the project team numerous cost-saving initiatives were
explored to prevent the project from exceeding budget.
Treatment of hazardous material rather than spoiling off site
meant that the risk of exposure to same would be limited to the
confines of the site.
The construction had a very low impact on surroundings/
environment and the end results has proved to have a high impact
on public perception and improved quality of life with an equally
positive long term impact on environment (treatment of hazardous
material, protection of birdlife). Through the rebuilding of the
pedestrian bridge the project was able to reinstate safe access to
area for the public and local business community. The project may
have a direct impact on the revival of Bruma business hub.
Project information
• Company entering: Basil Read
• Client: Johannesburg Development Agency (for
City of Johannesburg)
• Start date: June 2014
• End date: March 2016
• Main contractor: Basil Read
• Architect: JDLEA
• Principal agent: cba Specialist Engineers
• Project manager: LDM Project Management
• Quantity surveyor: Walker Mare Quantity Survey
• Consulting engineer: cba Specialist Engineers
• Subcontractor: ARQ
• Subcontractor: AfriSam
• Project value: R75-million
Winner