Standard Specification for Road and Bridge

SECTION 800 – QUARRIES, BORROW PITS, STOCKPILE AND SPOIL AREAS

801. GENERAL
Unless otherwise stated in the contact, it is the responsibility of the Contractor to select the sources of aggregates for concrete, stone for base, sub base, bituminous mix base binder course and wearing course, chipping for surface, rock fill for swamps etc. and the sources of natural/suitable materials, such as fill material, for the construction of embankments, gravel for sub base, base, surfacing and shoulder. Such sources shall be designated as rock quarries, quarries, alluvial deposits and borrow and are defined in Clause 802. Certain rock quarries, quarries, alluvial deposits, borrow pits may have or have been identified prior to the commencement of the contract and the Engineer shall instruct the Contractor as to which of these shall be utilized for the extraction as natural or suitable materials to be used in the works.

Provisions are included in subsequent clause of this Specification for additional rock quarries, quarries, alluvial deposits borrow pits to be identified and located by the Contractor during the contract. Stockpile and spoil shall be located by the Contractor subject to the approval the Engineer.

802. DEFINITIONS
(1) Rock Quarry
A rock quarry is an open surface working in massive rock form which stone is removed by drilling and blasting for use in the works.

(2) Quarry
A quarry is an open surface working form which stone or aggregate for sub base, base and surfacing are extracted for use in the works.

(3) Alluvial Deposit
An alluvial deposit is a site where gravel and aggregate of alluvial origin are extracted for use in the works.

(4) Borrow Pit
A borrow pit is a site from which loose material, other than stone, is removed for use in the works.

(5) Stockpile Area
A stockpile area is an area where material such as topsoil, fill material, gravel or aggregate is stockpiled prior to use in the works.

(6) Spoil Area
A spoil area is a site upon which surplus or unsuitable materials arising out of works are dumped within or beyond the road reserve as indicated on the Drawing or directed by the Engineer.

803. LOCATING MATERIAL SOURCES
(1) The Contractor shall be responsible for locating all material sources and for the acquisition or renting of all land required for rock quarries, quarries, alluvial deposit, borrow pits, spoil and stockpile areas and for access thereto in accordance with the Conditions of Contract.

The location and size of rock quarries, quarries, alluvial deposit borrow pits, spoil and stockpile areas proposed by the Contractor shall be subject to the approval of the Engineer.

The Engineer shall withhold his approval, if in his opinion the rock quarry, quarry, alluvial deposit, borrow pit, spoil and stockpile area, or access into them.
(a) will have a detrimental effect on the environment;
(b) would be very difficult to acquire;
(c) is in or near an urban centre;
(d) will require an access road which is excessively long;
(e) has excessively thick layers of overburden;
(f) covers too large an area;
(g) would constitute a danger to the public;
(h) is an excessive distance from the location where the material is to be used or removed from; or
(i) a source of suitable material is closer.

(2) The Contractor shall submit for the Engineer’s approval full information regarding the proposed location of the material source not later than 30 days after issue the order to commence the works of all rock quarries, quarries, alluvial deposits, borrow pits, spoil and stockpile areas that the Contractor will require for the whole the works.

The Contractor’s written notice shall include the following for each rock quarry, quarry, alluvial deposit, borrow pit, spoil and stockpile areas:
(a) A plan at 1:500 scale in ink on a stable transparent material giving details of:
i) plot boundaries;
ii) owners names and addresses, and if appropriate identification numbers;

iii) the District, Location, Registration Section and Number for each plot;
iv) local details such as building, fences, types and areas of cultivation and services, all agreed with the Land Owners; and
v) areas to be used for working areas, stockpile areas, safety blasting zones etc;

(b) Cadastral maps covering the areas to be acquired when available.

(c) Detail of the proposed access road route.

(d) Technical supporting information relevant to rock quarries, quarries, alluvial deposits, borrows pits, including:

i) Summary of geophysical surveys (electric, and/or seismic), geotechnical survey, indicating for alluvial deposit the thickness of layers, thickness of overburden, lenticular beds depth and configuration of the bedrock, etc., and in addition for rock quarries, the discontinuity families, the intervals between discontinuities, thickness and nature of the infilling, the Weathering Index.

ii) Laboratory results including petrographic identification, and for alluvial deposit material, grading, tests on the fine fraction (PI, SE, Methylene Blue test, Mica content, Organic matters), tests on the coarse fraction (LAA, AIV, ACV, Micro Deval, FI, Adhesivity test), CBR test, or for quarry material, LAA, AIV, ACV, Micro Deval, Adhesivity test, Specific Gravity, Water Absorption.

iii) Conclusions on qualities and quantities.

(3) Where the Contractor uses a rock quarry, quarry, alluvial deposit, or a borrow pit identified or instructed by the Engineer he shall obtain the Engineer’s approval of the areas required for the rock quarry, quarry, alluvial deposit, or borrow pit and of the siting of the access roads into the rock quarry, quarry, alluvial deposit, or borrow pit. The Engineer may required the Contractor to modify his requirements for any of the reasons outlined in Sub-clause 803 (1) (a), (b), (c), (d) or (f).

Where rock quarries, quarries, alluvial deposits, or borrow pits, available for inspection at the time of the Tender, are instructed by the Engineer the Contractor shall satisfy himself as to the quality and quantity of materials available before providing the information required in this Clause. Should such investigations reveal tat there is insufficient suitable material for the use for which such material sources were intended, the Contractor shall immediately inform the Engineer in writing and the Engineer shall either direct that such sources are extended or that new sources shall be used.

(4) When a rock quarry, quarry, alluvial deposit, borrow pit spoil or stockpile area has insufficient suitable material or area for the use for which it was intended the Contractor shall propose in writing that either any existing rock quarry, quarry, alluvial deposit, borrow pit, spoil or stockpile area be extended or that a new rock quarry, quarry, alluvial deposit, borrow pit spoil or stockpile area shall be used. The approval and acquisition of such new or extended rock quarries, quarries, alluvial deposits, borrow pits, spoil or stockpile areas shall in accordance with all the above provisions of this Clause for the acquisition of the original rock quarries, quarries, alluvial deposits, borrow pits, spoil or stockpile areas.

804. SAFETY AND PUBLIC HEALTH REQUIREMENTS
The Contractor shall comply with the prevalent laws and Regulations including those of the Local Authority regarding public health and safety in respect of the operation of rock quarries, quarries, alluvial deposit, borrow pits, spoil or stockpile areas, and in the absence of, or in addition to such Regulations, shall comply with the following conditions :-

(1) All areas of work, if they are not naturally under water, shall be drained and kept drained where a quarry or borrow pit has been excavated such that it will not drain naturally, it shall be kept pumped dry while being used.

(2) The Contractor shall confine his operations solely to the areas provided and shall demarcate the boundary of the area and erect temporary or permanent fencing as instructed by the Engineer.

(3) Where the height of any face exceeds 1 metre, the Contractor shall provide, erect and maintain at his own expense stock proof fencing and gates to prevent unauthorized access to the top of the working face.

(4) On completion of the work all faces shall be neatly trimmed to a slope flatter than 1:4. Where this is impracticable or where the working face is to be left exposed, the edge shall be permanently fenced, as instructed by the Engineer and measurement and payment for such fencing shall be in accordance with Section 400.

(5) On completion of work temporary fences and all temporary structures shall be demolished and removed. All latrine pits shall be filled in and drained. The site shall be topsoiled and left neat and tidy.

805. ACCESS ROADS AND TRAFFIC CONTROL
The Contractor shall comply with the provisions of Clause 103 and with the Conditions of Contract with regard to the construction and maintenance of access roads to rock quarries, quarries, alluvial deposits, borrow pits spoil and stockpile areas and with regard to traffic operations thereon.

806. SITE CLEARANCE AND REMOVAL OF TOPSOIL AND OVERBURDEN
Unless otherwise specified in the contract or instructed by the Engineer, the Contractor shall clear the sites of all rock quarries, quarries, alluvial deposits, borrow pits, spoil and stockpile areas in accordance with Section 200 but measurement and payment shall be made in accordance with this Section. All existing fences, tree, hedges and other features which the Engineer shall instruct shall not be removed or otherwise dealt. They shall be protected in accordance with Section 200.

Unless otherwise directed by the Engineer, the Contractor shall remove topsoil and/or overburden from rock quarries, quarries, alluvial deposits, borrow pits and spoil and stockpile areas. The Engineer shall direct whether topsoil shall be stripped and stockpiled separately or shall be excavated and spoiled together with the overburden. If suitable, the Engineer may direct for the use of overburden in the works.

On completion of the work in any rock quarry, quarry, alluvial deposit, borrow pit, spoil or stockpile area the overburden and/or topsoil which has not been used in the works shall be pushed back, spread and landscaped over the area of the rock quarry, quarry, alluvial deposit, borrow pit, spoil or stockpile area. Where topsoil has been stockpiled separately, it shall be pushed back and spared over the rock quarry, quarry, alluvial deposit, borrow pit, spoil or stockpile area after landscaping unless the Engineer has instructed that it shall be used for topsoiling in accordance with Section 600.

807. SELECTION, MIXING AND STOCKPILING OF MATERIALS
Before a quarry, alluvial deposit or borrow pit is opened, the Engineer shall instruct the Contractor as to the type of material to be excavated and the areas and depth to be worked. The Engineer may require specific operations of equipment according to the characteristics of the raw material and the characteristics of the final product to be obtained in accordance with Clause 808 and 809 or other relevant Section of those Specifications.

The Contractor may be required to mix selected material by bulldozing into stockpiles and/or face loading by shovel. The stockpiles shall be formed at least six weeks before intended use of the material which are to be treated and at least three weeks before intended use for materials which are not to be treated.

The Contractor shall ensure that oversize material, clay humus or unsuitable material encountered in the working operations is separated from the materials proposed for use in the works and such inferior material shall be removed tot spoil. A separate stockpile shall be used for each type and grading of material.

When removing material from stockpiles, none of the underlying material shall be mixed with it, and generally at least the bottom 100 mm layer shall be left behind. Should any stockpile prove surplus to requirements, the Contractor shall spread the material over the area of the quarry or borrow pit unless directed otherwise by the Engineer.

808. PRE-SELECTION OF MATERIALS
When necessary to meet requirements of the Specifications for materials extracted from quarries or alluvial deposits the Contractor shall carry out a preliminary size selection or screening of the raw material as follows:

(1) Size Selection
The size selection shall be carried out by unloading the material through appropriate grids to select the size fraction which contains the required fraction of the required type of stone specified in the Specifications, based on the identification of the petrographic composition of the various size classes of the raw material through laboratory trials in accordance with Clause 506.

The size selection shall be carried out provided the conditions given in Table 8.1 are fulfilled where:
R_p (%) = the minimal ratio between the quantity of required material obtained after processing (including selection, crushing, screening etc.) and the initial quantity of raw material treated.

Q min (m³) = the minimal quantity of processed materials of such type required for the works.

A, B, = Classes of material to be produced designated in accordance with the General Classification of materials specified in Section 600.

Table 8.1: Conditions for Pre-selection of Size

Quality classes to be produced	Construction Work		Maintenance works
	Rp (%)	Q min (m3)	Rp (%)	Q min (m3)
A	40	7500	35	4000
B	70	85000	60	20000

(2) Quality Control of the Size Selection
Materials of quality classes A or B shall be tested according to their use in conformance with the relevant Sections of these Specifications.

When the requirements of the final products are not met, the Engineer may require the Contractor to control the quality of the size selection.

The quality of the size selection shall be assessed by sampling 1000 boulders or stone in every 500 m3 of pre-selected material and counting the boulders or stones of the required petrographic types. If the percentage of such boulders or stones in the sample is less than 0.8 of the expected percentage, the corresponding pre-selected materials shall be pre-selected again.

809. PROCESSING
The Contractor shall use adequate processing equipment and methods to achieve the characteristics and performance of the aggregates to be produced. The processing methods may include successive steps such as primary crushing, screening for elimination of fine and soft material, secondary crushing and recycling, washing.

The Contractor shall carry out site trials in accordance with Clause 507 using the Constructional Plant and methods proposed for selecting and processing the materials to demonstrate their suitability to achieve the material requirements specified in the Specifications.

(1) Crushing
The crushing process shall include all crushing stages, such as primary crushing, secondary crushing or grinding (after primary screening) tertiary grinding (after secondary screening), as necessary to meet the requirement of the final product specified in the Specifications.

The feeding hoppers shall be equipped with appropriate devices, such as drawer or vibrating metallic desk, to allow for a regular and full charge supply of the material to the crushers.

Depending on the type, size and characteristics of the raw material, equipment required to meet aggregate characteristic and performances requirements may include the use of equipment given in Table 8-2 according to the classes of quality of the materials to be produced.

Table 8.2: Crushing Equipment According to Quality Classes of Final Material Product.

Quality classes of the final product	Type of equipment
	Primary crushing	Secondary crushing or grinding	Tertiary Grinding
A or B
In general	Jaw Crusher or Gyratory Crusher (for more than 1000T/h only)	Cone Grinder or Gyratory Grinder (for more than 1000T/h only)
Quartzite & Sand Production	Gyratory Crusher (for more than 1000T/h only)	Cone Grinder or Gyratory Grinder	Cone Grinder (Gyradisc)
Limestone	Jaw Crusher or Large Opening Percussion Crusher	Impact Crusher (& recycling)
C1	Jaw Crusher	Cone Grinder (& recycling)
D1	Jaw Crusher	(& recycling)

 

(2) Screening
The Contractor shall eliminate polluted or soft materials after the primary crushing by screening the crushed materials through a 50 mm mesh screen. The Engineer may instruct the Contractor to modify the above mentioned size for the elimination of soft materials according to the results of the laboratory trials.

In case of materials sensitive to crushing, the Engineer may instruct the Contractor to carry out a secondary screening after the secondary crushing.

(3) Recycling and Sand Production
According to the type and quality of materials to be produced, and notably the sand materials, the Contractor shall include in the crushing process the recycling of the coarse fraction resulting from the primary crushing through the secondary crusher or through the secondary or tertiary grinder.

(4) Washing
Where the washing of aggregate is required to meet the cleanliness requirements, and notable for the chippings for surface dressing, the Contractor shall incorporate to the processing plant an appropriate washing station including adequate equipment such as vibratory washing machine, a washing screw, washing tube etc. and of adequate capacity.

Sand with too high mica content shall be washed using appropriate equipment such as screw classifiers, paddle wheel etc.

(5) Testing
Each type of final products shall be tested in accordance with the tests and frequencies of testing as specified in the relevant Sections of these Specifications.

(6) Records
The Contractor shall maintain records in respect of the following data throughout the production period:
(a) daily production
(b) testing result, in accordance with the test schedules specified in the relevant Sections of these Specifications.
(c) Incident occurred during the production, if any.

810. MATERIAL UTILISATION
All materials from rock quarries, quarries, alluvial deposits, borrow pits as instructed by the Engineer shall only be used for permanent works shown on the Drawing or instructed by the Engineer and any other use shall be subject to the Engineer’s approval.

811. MEASUREMENT AND PAYMENT
No separate measurement and payment shall be made in respect of all items in this Section, if otherwise not specified in the contract. The Contractor shall be deemed to have allowed the cost of complying all requirements of this Section elsewhere in his rates including al site clearance, overburden and topsoil removal, access roads to rock quarries, quarries, alluvial deposits, borrow pits, spoil or stockpile areas and reinstatement including landscaping and spreading topsoil.

Where the Engineer has instructed that overburden or topsoil will be used in the works, measurement and payment shall be in accordance with the relevant Sections of these Specifications.