The Civil Engineering Contractor November 2018 | Page 21

ON SITE
Group’s Civils division, under
CEO Archie Rutherford, is aimed
at transforming it into a one-stop
contractor. The Civils division
specialises in the construction of roads
and earthworks, as well as installation
of services such as water, sewer,
and stormwater reticulation. It has
also established a Concrete division
specialising in all forms of structural
concrete work.
“We have a substantial and growing
pipeline of project work. I am
confident that the group will grow to
be in a position to compete with the
large public construction companies
in the near future. Apart from being
majority black women-owned, most
of our staff are young, which means
they represent the next generation of
management and technical expertise,”
Moodley says.
Scope of work
There are currently between 50 and
60 people working on site at any time
— a number which is anticipated to
ramp up considerably in the medium
term, before civils work ends in
about one year. Motheo site agent
Helgard Brink explains that Motheo
has been tasked with Phase One of
the development, encompassing the
provision of bulk services of the 7.5ha
site. This phase includes construction
of about 3.8km of asphalt roads,
requiring 36 000m 3 of earthworks
and layer works.
The scope of work also involves
construction of 3 500m of stormwater
piping, 1 900m of water pipes, and
500m of sewerage pipes, as well as four
attenuation ponds requiring 8 000m 3
of excavation and waterproofing with
HDPE (high-density polyethylene)
liners. A multi-barrel portal culvert
bridge construction over a perennial
waterway adds to the complexity. A
major component of the scope is the
bulk electrical connections, requiring
the upgrade of two municipal
electrical substations to facilitate the
development. There are two main
intersections to be constructed, and
some road widening, to facilitate
access to the development.
The much larger Phase Two will
involve construction of the residential
units and communal facilities. A total of
7.5ha of clearing had to be undertaken
in preparation for the construction
of the roads, attenuation ponds, and
pipelines. The four attenuation ponds
are to be constructed to manage water
run-off caused by flash floods. Due to
the large surface area of the site, about
4 000m 3 of attenuation volume
will be created, as compared to a
500m 3 or 600m 3 volume on a more
typical site.
“We are catching the bulk of the
water run-off on site, caused by the
hard surfaces created on significant
portions of the land. This will
allow the overflow to be released
back slowly into the natural water
system. Every new development
has to have such ponds to catch
floodwater that, in the normal course
of events, would naturally drain off,
but which is prevented from doing
so by consolidation of the surfaces,”
says Brink.
The bridge over the river requires
400m 2 of concrete and 45 tonnes of
steel. Most of the concrete is precast
for the bridge’s portal culverts,
with three barrels of three-by-three
culverts. In the past, the site had also
been used as an informal dumping
area. This has to be removed, and
later taken off site to a solid-waste
landfill site.
The underlying dolomite required
careful design consideration from what
would be a typical plan. For instance,
the water pipes had to be built with
more expensive HDPE pipes and the
sections welded together to ensure
there was no leakage. “The site is
highly sensitive due to its dolomitic
nature, and dolomite doesn’t like
water. We therefore needed special
pipes that would not leak,” says Brink.
The contractor was appointed on
20 April. Permits and way leaves
were granted, and the contractor
commenced
construction
on
28 May. Works are scheduled to
be completed by 29 May 2019.
The design of the works has also
The project includes the construction of 3.8km of asphalt
roads, requiring 36 000m 2 of earthworks and layer works.
www.civilsonline.co.za
CEC November 2018 | 19