9 SADS 1200 DE-1984 Small earth dams

5.2.3.3

5.2.3.4

5.2.4 5.2.4.1

5.2.4.2

5.2.4.3

5.2.4.4

5.2.4.5

5.2.4.6

5.2.5 5.2.5.1

5 ..2.5.2

6. 6.1

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.

SABS 1200 DE-1984 Small earth dams

Item

1) Embankment crest level ............................. 2) Horizontal crest width ............................. 31 Horizontal width of rockfill and earthfill zones ... 4) Thickness of filter and drainage layers ............ 5) Thickness of rip-rap ............................... 6) Topsoil thickness on downstream face ...............

layers, rip-rap, and crest ....................... 8) Gravel capping ..................................... 7) Hoxizontal position of earthfill zones, filter

1 As stated in the project specification, if required.

10

PD from designated dimensions, mm

Degree of accuracy :[I1 11 I

* + 100, - 0 * * 2 300

2 300 * *

* + 100, - 0 * * + 25 % of specified *

thickness, - 0 + 50, - 0

* 2 500 * - 0, no top limit

* *

6.2

7. 7.1

7.2

7.3

7.4

7 . 5

tII

POSITIONS, LEVELS, DIMENSIONS, AND MOISTURE CONTENT a) positions, levels, and dimensions. Subject to the lines of the completed work being satisfactory to the Engineer, the following tolerances shall apply to the positions, levels, and dimensions of the finished work, due allowance being made for the expected settlement given on the drawings or specified in the project specification:

I1 I

* *

Item

2 2 * + 3 , - 1 * + 1 , - 3 *

1) Homogeneous fill material...........................

2 ) Core zone .......................................... 3) Outer zones ........................................ 4) Random fill material ............................... 5) Dispersive soil ....................................

* As stated in the project specification, if required.

+ 2 , - 3 : I + 3 , - 0 I : Should the results of the tests on any particular layer or part of a layer of a compacted fill show that the moisture content is not within the appropriate of the limits given above, the compacted layer or part of the layer shall be harrowed and wetted or dried, as applicable, and recompacted, all at the Contractor's expense.

TESTING EXPLORATORY HOLES. The Engineer may require the Contractor to drill, auger, or excavate holes in advance of the start of construction to determine founding conditiona or for other purposes. when so requested by the Engineer, the Contractor shall provide labour, tools, machinery, and equipment for sinking such exploratory holes and for refilling them. The operations specified in this subclause will be paid for as daywork.

TAKING AND TESTING OF SAMPLES. The Contractor shall carry out sufficient tests to satisfy himself as to the consistency of materials placed in embankments, around and over pipes, and as backfill to structures. In addition he shall carry out routine compaction control tests to ensure that the specified densities are being attained. Records of the test results and the Working sheets shall be kept in a systematic manner and shall be submitted to the Engineer on a regular basis. Routine in-situ control tests will be carried out by the Engineer at such frequency as he considers necessary for the proper evaluation of the quality of the embankment, etc. (See also 5.2.3.2(e) and 8.1.3.)

MATERIAL OR COMPACTION STANDARD NOT TO SPECIFICATION. Where the Engineer's tests reveal that the material used does not comply with the applicable requirements of the specification, or that the compaction specified has not been attained, the Contractor rihall so rectify the work that the material complies with the said requirements and the compaction specified is attained.

TRIAL EMBANKMENT. The Engineer may order the construction of a trial embankment to test the properties and compaction characteristics of the earthfill material. In such an event the Contractor shall construct the trial embankment in the manner specified for the main embankment. Payment for such work will be made in terms of 8.3.7.

DENSITY. The density of the earthfill shall be measured in accordance with the standard Proctor test (see ASTM D 698). Should the average Proctor density determined from 10 consecutive routine compaction control tests at random locations in the earthfill fall below the specified density, the Engineer may order that, before further material is placed, the Contractor submit a revised compaction procedure for approval by the Engineer.

11 SABS 1200 DE-1'784 Small earth dams

8 . 8.1 8.1.1

8.1.2

8.1.3

8.1.4

8.2 8.2.1

8.2.2

8.2.3

8.2.4

8.3 8.3.1 8.3.1.1

8.3.1.2

5.3.1.3 8.3.1.4

8.3.1.5

Should the Engineer consider that any area in the earthfill is not receiving adequate compaction he may require specific tests to be carried out. should the Proctor density determined in any specific test be more than 5 percentage points belor that required for the layer, the material in the area of work represented by that specific test shall be reworked until it complies with the said requirement or it shall be removed from the emhankment, as directed, at the Contractor's expense.

MEASUREMENT AND PAYMENT BASIC PRINCIPLES General. Except where the small dam forms part of a project necessitating the inclusion of SAUS 1200 A in the contract document, measurement of and payment for preliminary and general liabilities will be dealt with in terms of Subclause 8.3.1 of SABS 1200 N). Measurement. The basic principles of measurement of the volume of the earthworks required f o r the construction of a small dam are as follows: a) The quantity will be measured only as fill in the embankment, a separate item being scheduled for each source from which such fill is to be obtained; b) Excavations that are necessary for the core trench, footings, spillway, and ancillary works will l!r measured as for the creation of the hole only; c) Borrow areas will be designated; d) Agreement must be reached on Site as to the proportion of each zone of the embankment that is to c'unie from each source. The measurement of depths for restricted excavations (see 3.1.2(aI (2)) will be based on the assumption that untrimmed general earthworks or bulk general excavation to finished level, or both, were complctt~d before the restricted excavation was started. Payment. The basic principle of payment for earthworks is that, except in the case of 8.1.Z(b), the rat.e shall cover the cost of excavation, haulage, and re-use (spreading and compacting) in forming embankments, terraces, etc., and the disposal of surplus material within an area designated on the .drawings or in the project specification. The cost of additional tests carried out by the Contractor will be dealt with as daywork provided that, where the results of the tests indicate that the materials or workmanship, or both, do not comply with the applicable requirements of the specification, the cost shall be borne by the Contractor. Where the results of the tests prove compliance with the specification, the cost will be borne by the Employer. Classification of Excavations. Separate items will be scheduled for each part of the work covered by 8.1.2(b). The material excavated will, where practicable, be regarded as bulk excavation and will be classified in terms of 3.1.2(a) (l), (b) (l), or (c), as applicable.

COMPUTATION OF QUANTITIES General. Subject to the terms of 8.2.2, the volume of' embankments (see 8.1.2(a)) and excavations (see 8.1.2(b)) will be calculated from the original levels and the dimensions of the finished shapes, sections, and profiles as shown on the drawings or ordered. No embankment fornied and no excavation made outside the specified lines and levels will be included in the measurement unless such extra work has been done on the written instructions of the Engineer. Volumes of material removed incidentally during site clearing operations as specified in 5.2.1.1(a) and (b) will be neglected in both embankment and excavation quantities, but the volumes (calculated from the areas and depths) moved in the stripping of the site in terms of 5.2.1.2 or in excavation of stated depths of topsoil will be added to the embankment volume or deducted from the excavation volume, as applicable. Checking Cross-Sections. Should he wish to check the Engineer's quantities, the Contractor may, at his own expense, take the levels and prepare the cross-sections necessary for the measurement and computation of quantities. The Engineer may conduct such check tests on the Contractor's cross-sections as he considers necessary to confirm their accuracy and adequacy. Failure on the part of the Contractor to submit his own cross-sections to the Engineer before commencing construction will be held to indicate his preparedness to accept the levels and cross-sections provided by the Engineer for the purpose of measurement and payment of quantities and, in the event of such failure, no subsequent claim in this regard will be considered. Rip-rap. The volume of rip-rap will be computed by multiplying the specified controlled thickness (see 2.3) by the surface area of the embankment as determined from the levels existing after stripping and excavation of the foundation, and from the slopes given on the drawings or ordered. Filter and Drainage Layers. The volume of sand and gravel materials imported for use in filter and drainage layers will be computed from the finished shape, sections, and thickness shown on the drawings or ordered. Unless extra work has been done on excavation for filter and drainage layers on the written instructions of the Engineer, no allowance will be made for extra materials used.

SCHEDULED ITEMS site Clearance

The area measured will be that ordered in writing or shown on the drawings to be cleared and stripped. Except for the removal and disposal of trees and stumps of girth exceeding 1 m, the rate shall cover the cost of complying with 5.2.1.l(a) and (b) and 5.2.1.2. Remove and grub large trees (complete with stumps) or stumps only, as scheduled, of girth a) over 1 m and up to and including 2 m ................................................... Unit: NO. b) over 2 m and up to and including 3 m ................................................... Unit: NO. c) over 3 m, in increments of 1 m ......................................................... Unit: NO. The girth of a tree or stump will be measured at the narrowest point of the tree or stump in the first metre of its height above ground level. Trees and stumps of girth exceeding 1 m will be measured individually and classified according to size in increments of 1 m as indicated above. The rate shall cover the cost of clearing and grubbing trees and stumps of all sizes, cutting branches, backfilling holes, and removing, transporting, and disposing of all such trees, stumps, and branches and associated material.

Extra-over 8.3.1.1 for removal and recovering of fencing .................................. Unit: The rate shall cover the cost of complying with 5.2.1.l(d). Extra-over 8 . 3 . 1 . 1 for recovering other scheduled material ................................ Unit: Sum The sum shall cover the cost of complying with 5.2.1.l(e) for the material scheduled.

--

Clear and strip Site Unit: ha or m 2 ......................................................................

Extra-over 8.3.1.1 for removal of rocks, etc.. as specified in 5.2.1.l(c) Unit: m 3 ................. m3