UATERIALS POR REINSTATEMENT OY ROADS AND PAVED AREAS
Subbase and Base, Where trenches cross or run along surfaced roads and paved areas of which the surfaces
are scheduled to be reinstated, the Contractor shall obtain prhor approval of subbase and base materials
that may be required to supplement such materials lost during ercavation.
Gravel. Where trenches cross or run along gravel roads of which the surfaces are scheduled to be
reinstated, the Contractor shall, for the purpose of reinstatement, separately store the top 300 mm of
material excavated.
Bituminous Construction. Materials for bituminous construction shall comply with the applicable
requirements of the appropriate of the following specifications:
Primer ......................................... SABS 748 or SABS 749
Cutback bitumens or emulsions ..................... SABS 308 or SABS 309
Coarse aggregate (stone chips) .................... SAEG 1083
Asphalt Carpet. An asphalt carpet shall consist of either of the follouinq mixes:
a) 6,7 mm coarse aggregate (stone chips) .......... 100 parts by mass, plus
RC 250 cutback bitumen ......................... 7 parts by mass of emulsion
premix Grade 60 bitumen emulsion 8 parts by mass of emulsion
or
b) 6,7 mm coarse aggregate (stone chips) .......... 100 parts by mass, plus ...............
SELECTION. The Contractor, in addition to complying with 5.4, shall not wastefully dispose of excavated
material that complies with 3.3 and 3.4.
The Contractor is not required to use selective methods of excavating but may, if he so wishes, screen,
wash or otherwise treat excavated material in order to produce material suitable for the bedding. He
shall take positive steps to avoid burying or contaminating materials which otherwise would be suitable
for use as
a) selected fill for the blanket or selected granular mateiial for the cradle, unless other materials
have been specified, or
b) topsoil, or
c) road materials for re-use in terms of 5.9.
when otherwise suitable material from a trench is contaminated, the Contractor shall, to make up any
shortfall, obtain (at his own expense if the contamination is due to his methods of working) suitable
material from other excavations on the Site, or by opening up borrow pits, or by importing from commercial
or other sources.
Subject to the requirements of 3.5, hard rock and boulder13 from excavations that conform to the
classification given in Subclauses 3.1.2(c)-(e) (inclusive) of SABS 1200 D or Subclauses 3.1.2(c)-(e)
(inclusive) of SAES 1200 DA, as applicable, shall be incorporated in the backfill. The Engineer m y
direct that the material be suitably mixed with other backfill material.
PLANT
EXCAVATION EQUIPMENT. The Contractor may use trenching plant that will excavate to a width such that the
side allowance does not exceed the appropriate value specified in 5.2 by more than 50 X , except that
where, in terms of the project specification or of the drawings, the base width of a trench for a
pipeline or a portion of a pipeline is not to exceed the minimum base width or a stated value, the
Contractor shall use trenching plant that will produce the required trench width or he shall accept
responsibility for all costs incurred in strengthening the relevant pipeline.
CONTROL OF WATER. The Contractor shall use appropriate techniques or provide plant such as pumps, well
points and sheeting or close timbering for keeping the trenches sufficiently free from water to enable
him to lay pipes true to line and level and to bed them soundly, all as specified in this specification
(see 5.1.2).
COMPACTION EQUIPMENT. The Contractor may use mechanical compaction equipment but he shall select such
equipment and operate it in such a manner that the pipeline, duct or cable is not stressed or damaged.
Machine compaction shall not be used directly above the pipe until sufficient backfill has been placed to
ensure that machine compaction loads transmitted to the top OF the pipe are no greater than would be
imposed by nonnal road traffic over a pipeline with cover of depth 600 mm.
CONSTRUCTION
PRECAUTIONS
General. The requirements of Subclause 5.1 of SABS 1200 D or Subclause 5.1 of SABS 1200 DA, as
applicable, shall apply in addition to the requirements of _ _ -- - 5.1.2 below.
Stormwater, Seepage and Dewatering of Excavations
Throughout the Works. In dealing with water as required in terms of Subclause 5.5 of SABS 1200 A or
Subclause 5.3 of SABS 1200 AA, as applicable, and Subclause 5.1.3 of SABS 1200 D or Subclause 5.1.4 of
SABS 1200 DA, as applicable, the Contractor shall, subject only to such particular items as are scheduled
for designated hazards in terms of 5.1.2.2, properly and adequately protect the Works from flooding and
damage by stormwater, flow from springs, and seepage.
Special water hazards. The Engineer may schedule particular items for dealing with a special water hazard
at a designated point or in a designated part ot the Works and as required in terms of the project
specification (see 8.3.2 and 8.3.4(b)).
Sloping ground. In the case of a trench on sloping ground, the Contractor shall take approved measures
(such as the construction of cross-embankments) to minimize erosion in the trench and adjacent ground
from which vegetation has been removed.
Accoemodation of Traffic and Access to Properties. Where the work affects the operation or safety of
public traffic,
a) in addition to complying with the relevant requirements of Subclause 5.1.6 of SABS 1200 D or Subclause
5.1.8 of SABS 1200 DA, as applicable, the Contractor shall
1) constmct or put in order such bypaes(e6) as may be required to deviate traffic from portions of the
road that are to be affected by the construction; or
2) where half-width construction is ordered or approved (as in the case of most direct crossings of
roads), so arrange his work that the traffic will at all times have free one-lane access to at least half
the width of the roadway;
3) wherever possible, where half-width construction is used, ensure that the whole road is open at night
and, at the end of each day's work, is left in a good and safe trafficable condition, complete with the
traffic signs and the protection facilities specified in Subclause 5.1.6 of SABS 1200 D or Subclause
5.1.8 of SABS 1200 DA, as applicable;
7 SABS 1200 DB-1989
Earthworks (pipe trenches)
4) ensure that the usable width of road is,
i) for two-way t r a f f i c , at l e a s t 6 m, and
ii) for single-lane t r a f f i c , at least 4 m for each lane; and
b) the Contractor shall provide and allow reasonable access to persons occupying properties that f a l l
within or adjoin the area over which he is working. If, for any reason, such access has to be closed for
any period(s) during the construction period, the persons affected shall be given reasonable notice, in
writina. of each such neriod of closina. <.
Existing Services that Intersect or Adjoin Trenches. The requirements of Subclause 5.1.2 of SABS 1200 D
or Subclause 5.1.3 of SABS 1200 DA, as applicable, shall apply.
MINIMUM BASE WIDTHS. Unless otherwise specified (see 4.1) i n the project specification or on the
drawings or elsewhere in the specifications, the base width of a trench (see Drawing DB-4) s h a l l be not
less than the exteriial diameter of the pipe barrel plus t w i c e the side allowance determined from the
following table :
External diameter of pipe barrel, oun Side allowance on each side, mm
I
Over Up to - and including - 125
125 700
700 1 000
1 000 2 000
2 000 -
300 (See (b) below)
300
400
500
600
a)
bl
Where t w o or more pipes are to be placed i n one trench, the base width of the trench shall be not less
than the sum of the external diameters of the pipe b a r r e l s plus the side allowance for each outer pipe
plus, between each pair of adjacent pipes, the average of the side allowance for each pipe.
The minimum base width for pipes of external diameter not exceeding 125 mm and laid at a depth not
exceeding 1,5 m may be less than 600 mm for flexible continuous piping t h a t , in terms of the drawings,
project specification or schedule, requires no bedding or jointing in the trench.
SITE CLEARANCE. The Contractor s h a l l c l e a r (as specified i n SABS 1200 C) an area of sufficient width
along the route of the pipeline t o ensure t h a t h i s selection operations are not hampered (see 3.7).
Where trenches are i n servitudes or wayleaves of specified width, the Contractor shall ensure that
clearing and damage t o plant growth is r e s t r i c t e d to the servitude or wayleave area.
EXCAVATION. Pipe trenches shall be excavated in lengths approved by the Engineer, to widths t h a t , in
each case, provide at l e a s t the appropriate side allowance (within trench supports and wales, i f any)
given in 5.2, and such that half of the base width is on e i t h e r side of the designated centre-line of the
pipe. The sides of each trench from the b o t t o m up shall be as nearly v e r t i c a l as possible for at least
the height of the bedding. (See also the requirements relating to the stockpiling of excavated material
given in 3.7 and those relating to excavated material given in Subclause 5.1.4.3 of SABS 1200 D or i n
Subclause 5.1.6 of SABS 1200 DA, as applicable.)
TWCH BOTTOM. Material t h a t the Engineer considers to be unsuitable as the b o t t o m of the trench shall be
excavated to the depths and disposed of in the manner directed. The resulting space s h a l l be r e f i l l e d ,
as ordered, with approved material and compacted as directed.
Should bedding of the pipeline in accordance with SABS 1200 LB form part of the contract, the depth of
the trench shall be such t h a t the specified depth of the cradle can be placed under the pipeline, and the
trimming and grading of the b o t t o m of the trench shall be such t h a t the barrel of each length of pipe can
be uniformly supported over its f u l l length, free at the joints, and a t the correct grades and levels.
Except where the trench excavation is in rock, hard objects and boulders that may adversely a f f e c t the
uniformity of the foundation shall be removed t o a depth of 100 nun b e l o w the specified trench b o t t o m .
Where the b o t t o m of the trench has been loosened during excavation, it shall be compacted a t OHC to 90 %
of modified AASHTO maximum density prior t o bedding and pipelaying.
The bottom of trenches s h a l l be s u f f i c i e n t l y s t r a i g h t (or true to alignment i n the case of curved
pipelines) to enable the pipes to be laid without reduction of the side allowances given i n 5.2 and in
conformity with the applicable tolerances specified i n any standardized specification covering pipework
t h a t forms p a r t o f the contract.
BACKFILLING
General. Backfilling of pipe trenches s h a l l commence a f t e r the pipe has been laid and firmly bedded in
the specified cradle and the blanket has been placed and adequately compacted a t OMC around, under the
overhang and over the top of the pipe to the height of blanket cover specified elsewhere in the contract
(see Drawing DB-1).
Backfilling shall be carried out i n accordance with 5.6.2 over the f u l l e x t e n t of the actual trench
excavation and to original ground level, except where otherwise directed. Unless prior approval has been
obtained, no f i l l i n g shall be placed i n water. (See also 5.1.2.)
Material for Backfillinq. Unless the Contractor is authorized by the Engineer to use other material
(see 5.6.5), material for backfilling above the bedding (cradle and blanket) s h a l l be obtained from
trench excavations.
Hard and rock material s h a l l be incorporated in the b a c k f i l l above the bedding only to the extent
approved. Depending on the quality of the material, the Engineer may d i r e c t t h a t it be suitably mixed
with other b a c k f i l l material.
In areas subject to road traffic loads and where the available backfill has a PI higher than 12, the
Contractor shall obtain specific instructions f r o m the Engineer before proceeding with the placing of the
backf ill,
Disposal of Soft Excavation Material. Excavation material f r o m the trench, which is unsuitable or has
become surplus because of bulking, displacement by the pipe and importation, shall be disposed of along
the trench servitude within the freehaul distance from the source of such excavation material, unless
otherwise required in terms of the project specification.
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