CHAPTER TWO - MEASUREMENT OF EARTHWORK
Excavation is measured by volume and the quantities are given in the Bill of Quantities in m3. Description features for excavation and a summary of the CESMM notes are given in Table 1. Excavation is measured the net size of the excavated void with no allowance for working space. The volume being that before the material is excavated.
The item descriptions for excavation state what happen to the excavated material when it is excavated whether the material is "for re-use" or "for disposal" (meaning disposal off site or disposal on site), the location of the disposal must be stated. If for disposal on site there is a spreading or other deposition requirement it must be identified in the item description. If there is a filling requirement, such as spreading of the material to designed profiles, a filling and compaction item in addition to the excavation item should be measured.
|Unless otherwise stated all excavations are deemed to be in natural material other than top soil or rock and all excavated materials are deemed to be for re-use. The excavation in an item is deemed to start at the Original Surface and finish at the Final Surface. The item descriptions "Excavation of cuttings" or "Excavation of foundations", "General excavation" without further wording, each denoted by application of the provisions above. The material to be excavated is natural material other than top soil or rock, that it is for re-use and that the excavation in the item starts at the Original Surface and finishes at the Final Surface. Works for which separate items are not required are noted in the first panel of Table 2.1 (Source : CESMM).|
|2.1.1 Excavation Of Cuttings|
Excavation of cuttings is measured by volume and is given in m3 in the Bill of Quantities. Example of item description for the excavation of the cutting is shown in cross-section in the diagram, Figure 2.1 and Table 2.2. The item description assume :
i) The excavation starts at the Original Surface and finishes at the Final Surface,
ii) There is no top soil at the Original Surface,
iii) All material excavated are for disposal.
The quantity attached to an item would be the volume of the material to be excavated. The excavation of cuttings sometimes require to be measured in stages.- It is normal for a specification to require that the bottom of 150-300mm of the excavation is left, to protect the formation, and excavated immediately prior to the laying of the base material.
Similarly, where is the top soil and it is specified to be excavated separately form other material. The excavation of the top soil is a stage of excavation for which a separate item must be given.Figure 2.3 and Table 2.2, below shows excavation of the cuttings, in stages. The item descriptions assume :
|2.1.2 Excavation For Walls at Sides Of Cuttings |
When wall are required at the sides of cuttings, the excavation to accommodate the wall and its backfilling is classified as general excavation. The depth of the excavation being taken down to the formation of the pavement abutting the face of the wall. Any excavation below the pavement level classified as excavation of foundations. This is illustrated in Figure 2.4. Additional detail could be provided by a diagram on the drawings indicating the measurement for measuring the excavation. The CESMM requires that item descriptions for "Excavation of Foundations" must state the location and limits of the excavation where is not clear.
2.1.3 Excavation below embankments
Where an embankment is to be constructed on steeply sloping round, the surface may be specified to be benched in steps or trenched. The steps or trenches can be classified as "Excavation of cuttings", it should be identified by the phrase "benched in steps below embankments" or "trenched below embankments.
2.2 GENERAL EXCAVATIONS
2.2.1 Excavation for Structure and Foundations
The volume measured for the excavation of a structure or foundation is the volume occupied by or vertically above any part of the structure or foundation. The application of three situations is illustrated in the Figure 2.6.
2.3 EXCAVATION ANCILLARIES
2.3.1 Trimming of Slopes
|2.3.2 Preparation of Surfaces|
Preparation of surfaces is measured superficially in square meters to the extent that earthworks are to receive Permanent Works other than earthworks. The item covers merely preparing the surface to the required profiles and configurations. It would not include any material or additional
2.3.3 Double Handling of Excavated Material
Double handling excavated material is measured only when double handling is required. Consequently, excavation and filling items are deemed to include double handling that may be necessary to carry out the earthworks.
Double handling if excavated material is measure d by volume and is given in the Bill of Quantities in m3; The volume shall be that if the void formed in stockpile. When calculating the volume of double handling if excavated mate.ial for the quantities in the Bill of Quantities, an allowance will need to be made for the difference in bulk f the material in the stockpile and its bulk when used as filling.
When calculating the volume of material for double handling at the site the volume of the stockpile will need to be measured both before and after the material has been removed.
2.3.4 Dredging to remove silt
Dredging to remove silt is applicable only to silt which accumulated during the maintenance period and is required to be removed. The quantities for the Bill of Quantities will require to be estimated and measured on completion.
2.4 FILLING AND COMPACTION
|2.4.2 Embankments |
The classification embankments applies not only to those for roads and railways but also in dam construction. Embankments are measured by volume and the unit of measurements is in m3. The measured volume will include any designed volume for long term settlement. Specimen item description for the embankments shown in cross section in the diagram Figure 2.8 are given at table below the diagram.
|2.4.3 Filing and Compaction to Stated Thickness|
The classification "to stated thickness" applies to filling and compaction of a required thickness, such as a uniform bed or hardcore under a ground slab of a structure, a layer of draining material to form a drainage blanket, and the like.
Filling and compaction of this classification is measured superficially and the thickness is stated in the item descriptions. The actual thickness having been thus stated it is necessary to include that standard phrase ' to stated thickness " in the descriptions. When carried out on the surfaces inclined at an angle of exceeding 10 degrees to the horizontal the item description must so state. The unit of measurement is m2.
The descriptive feature "Pitching" applies to the facing of earthwork with stones of block of hard material, usually placed close together to protect the surface.
The work is measured superficially and is given in the Bill in m2, It must be stated in the item description when work is to surfaces exceeding 10 degrees to the horizontal. All item descriptions for pitching must state the nature and the dimensions and the depth or thickness of the materials used for the work. Nominal sizes for pitching, thickness 200mm, broken limestone size 200 x 150 mm.
2.4.5 General Filling and Compaction
General filling and compaction is the to make up levels over areas and in situations which would not be appropriately classified under the other Second Division descriptive features. The unit of measurements is m3.
2.5 EARTHWORKS : GENERAL GUIDELINES
i) Excavation measured with no allowance for bulking.
- Excavation rate = transportation + excavate + deposit cannot exceed 200m (RM 3.00)
- more than 200m distance of excavation and deposition the rate will rise (>RM 3.00)
iii) Separated item will be provided when the amount of filling required exceeds the amount from the excavation.
CHAPTER TWO - MEASUREMENT OF EARTHWORK...cont'd2.6 WORKED EXAMPLES
ASSIGNMENT (INDIVIDUAL): IMPORTANT!!!
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