Rockfill, rip-rap, drains, and filters
a) Stone for rip-rap shall be so placed on the bedding layers as to produce a reasonably well-graded mass
of rock with the minimum practicable percentage of voids.
b) The larger stones shall be well distributed and the entire mass of stones in their final position
shall be roughly graded to conform to the gradation specified. The finished rip-rap shall be free from
unacceptable pockets of small stones and clusters of large stones. Rip-rap shall be placed to its full
course thickness in one operation and in such a manner as to avoid displacing the bedding material. The
finished layer of rip-rap shall be a well-integrated, stable mass of rock.
c) Unless otherwise specified in the project specification, no compaction will be required for rip-rap.
d) Non-vertical filter layers may, subject to approval, be connected with short vertical sections (giving
a stepped effect), to suit the Contractor's method of working. The cost of extra material used for this
purpose will be for the Contractor's account.
e) Rockfill for use in the downstream toe and other portions of the embankment shall be dumped, and
exposed surfaces finished off to present a neat appearance. Unless otherwise specified in the project
specification, no compaction will be required for rockfill materials.
f) Where any source of rockfill is designated, no guarantee is given or implied that the source will
provide material that complies with 3.2.3 as regards quality or grading limits, or that it will be
adequate in quantity. Where any part or the whole of a designated source of rockfill does not comply
with 3.2.3 or is not adequate in quantity, the Contractor shall locate and obtain approval for one ur
more other sources of rockfill and the terms of 5.2.2.3 and 5.2.5 shall apply to such material and the
source ( 6 ) .
Rockfill and filter materials that do not comply with the requirements of 3.2.3 for quality and grading
limits shall not be used and shall be removed from the Site.
Backfilling around structures (outlet works)
a) General. No backfilling shall be commenced until permission to do so has been given by the Engineer.
Embankments shall be constructed simultaneously on both sides of structures to minimize unequal loading.
Where shown on the drawings or ordered, all trenches and other excavations outside structures shall be
carefully refilled with approved material in layers of thickness not exceeding 250 mm uncompacted.
During the placing of each layer, the fill material shall be well rolled and compacted, sufficient water
being added uniformly to ensure that the density specified for the particular zone is achieved. Each
layer shall be completed before the next is added.
In general, fill material shall not be deposited in water but it may be so deposited in exceptional
circumstances (such as to facilitate dewatering) with the prior consent of the Engineer.
b) Restricted. Where the use of conventional plant for compacting adjacent to a structure is not
possible, the material to be compacted shall be spread in loose layers of thickness not exceeding 250 mm
and compacted by means of mechanical tampers to at least the density specified for that particular zone.
Finishing
Final grading. On completion of earthworks to the finished level and of backfilling of all trenches, the
whole surface shall be graded, shaped, and compacted to final grades and levels.
Gravel cappin . After the final grading has been completed, the Contractor shall place the gravel
capping and c%rpact it to a Proctor density of at least 95 % and a compacted thickness of at least
300 mm.
Topsoiling. Where scheduled, topsoil on level and slightly graded areas shall be lightly compacted by
wheeled vehicles or by tamping, and trimmed neatly to the required lines, grades, and levels. The final
thickness of topsoil after compaction shall be at least 75 nun.
Grass or other vegetation. Where and as scheduled, grass or other vegetation shall be planted after
topsoiling has been completed. On completion of planting, the planted area shall be neatly trimmed and
well watered.
The Contractor shall ensure that the planted areas are not permitted to dry out. Any grass or other
vegetation, as applicable, which fails to grow shall be replaced by the Contractor at his own expense
with fresh grass, or other vegetation, or seed, as appropriate, until full cover is obtained.
Where seeding of grass directly onto the compacted earthfill is ordered and scheduled, the Contractor
shall loosen the surface to a maximum depth of 20 nun, and apply seed and fertilizer at the rates of
application ordered or scheduled.
Pitching of surfaces. On completion of final grading in terms of 5.2.4.1, designated surfaces shall,
where scheduled, be pitched with stone or other materials of the type and in the manner shown on the
drawings and specified in the project specification.
Gabions. Where scheduled, gabions shall be constructed to the details and in the manner specified in the
project specification.
Transport for Earthworks
Freehaul. Provided that the quantity to be moved from (or to) a particular designated site to (or from)
the dam wall does not exceed 20 % of that scheduled or stated in the project specification for such
movement between such points, the haulage for use or for disposal of material in or from scheduled
excavations, embankments, borrow pits within the dam basin, and other designated borrow areas will be
regarded as freehaul. Where, in the case of any particular movement, the quantity actually handled
exceeds the said 20 %, the excess quantity shall be subject to a freehaul of 0,5 km.
Overhaul. Haulage of excavated material beyond the applicable freehaul distance specified in
5.2.5.1
will be regarded as overhaul. Irrespective of the method of haulage adopted for the movement of
excavated maierial from the point of excavation to the point of placing, overhaul distances will be
classified as follows:
a) Short haul:
b) Long haul:
The Contractor shall not incur overhaul expenses except where authorized in writing (see 8.3.8).
TOLERANCES
GENERAL. The degree of accuracy of the finished work and the permissible deviations (PD) (see Clause 6
of SABS 1200 A, SABS 1200 AA, or SABS 1200 AD, as applicable) shall be within the appropriate of the
limits given in 6.2.
Over 0,5 and up to 1,0 km in excess of freehaul by a designated route;
Over 1,0 km in excess of freehaul by a designated route.
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