SCOPE OF WORK

This specification covers the requirement for slope stabilization and shore protection works and shall include contractor’s designing, detailing, quarrying, selection, transportation, furnishing, installing, inspection and testing of the works and conform to the requirement of this specification and the approved drawing.

The Contractor shall stabilize the embankment slope and protected it from erosions by means of riprap or rubble masonry or sod facing or gabion, over a geo-textile layer as shown on the drawings or as directed by the Owner.

CODES AND STANDARDS

The contractor shall comply with the requirements of the applicable codes and standards published by the following organizations:

ASTM : American Society for Testing Materials

USBR : United States Bureau of Reclamation

SII : Standard Industri Indonesia

RIPRAP

MATERIAL

The riprap material in relation with their common engineering functions is stone with sound of rock type and the size range of stones shall be 15 - 60 cm.

Contractor shall propose the materials suitable for each engineering function, location and type of the works to the Owner for approval.

Material properties such as mass per unit area, density, hardness and type of rock, shall be determined by the Contractor and submitted to the Owner for approval.

SETTING

Riprap shall be furnished and placed to the lines and grades as shown on drawing or as directed by the Engineer.

Stone of riprap shall be placed over a gravel bedding to produce a dense and stable rock blanket over the surface requiring protection, and shall be constructed within the specified tolerance to the lines and grades as shown on the drawing.

Riprap shall be placed to its full coarse thickness at one operation and in such a manner as to avoid displacing the underlying material.

The larger stones shall be well distributed, with smaller rock filling the space between them.

The entire mass of stones in their final position shall be roughly graded.

The finished riprap shall be free from objectionable pocket of small stones and cluster of larger stones.

Rearranging of individual stones by mechanical equipment or by hand will be required at the extent necessary to obtain a reasonably well graded distribution of stone sizes.

RUBBLE MASONRY

MATERIAL

The stone for rubble masonry shall be natural or crushed stone.

The stoned used shall be clean and must be washed if necessary in the opinion of the Owner.

Unless otherwise shown on the drawings, stones shall have minimum size not less than 25 cm.

The stones shall show a face of not less than 0.03 square meters and not more than 0.10 square meters in area and none shall be less than 125 mm in depth, they shall be laid to give a uniformly random apprearance and shall be selected in laying so as to present at even distribution of large and small stones on the face.

The rubble stone shall be placed with 1:3 cement - mortar after having joints throughly moistened the spaces between the stone and the surface joint shall be filled with 1: 3 cement - mortar.

PLACING

The rubble stone shall be hand - placed with uncoursed close joints to the line and grades as shown on the drawings or as directed by the Owner.

Where the rubble masonry is to be placed on a prepare foundation bed, the bed shall be firm and normal to or in steps normal to the face of the wall, and shall have been approved by Owner's before any stone is placed.

All stones shall be cleaned thoroughly and wetted immediately before being set, and the bed which is to receive them shall be cleaned and moistened before the mortar is spread. They shall be laid with their longest faces horizontal in full beds of mortar, and the joints shall be flushed with mortar.

The exposed faces of individual stones shall be parallel to the faces of the walls in which the stones are set.

If a stone is loosened after the mortar has taken initial set, it shall be removed, the mortar cleaned of, and the stone relaid with fresh mortar.

Care shall be taken to prevent the bunging of small stones or stones of the same size.

GABION

MATERIAL

The standard type gabions shall be a flexible hot-dip galvanized gabion with PVC coated of the type and size specified below. It shall be made of wire mesh of type and size as specified in the following:

· The mesh shall be hexagonal woven mesh, the joints formed by twisting each pair of wires through three half turns.

· The size of mesh conforms to standard specification issued by the factory and shall be not greater than 2/3 of the smallest stone filled in the gabion.

· All wire used in the fabrication of the gabions and in the wiring operations during construction shall be galvanized and "Mild Steel Wire", with an average tensile strength of 44 kg/sq.mm.

· The diameter of the wire used in the fabrication of the netting shall be not less than 3.2 mm according to engineering requirements.

The standard gabions shall have the following dimensions:

§ Length : 2.0, 3.0, or 4.0 m.

§ Width : 1.0 m

§ Height : 1.0 m for boxes, 0.3 or 0.5 for mattresses.

Sufficient lacing and connecting wire shall be supplied with the gabions for all the wiring operations to be carried out in the construction of the gabion work. The quantity of such wire is estimated to be 8 percent of the gabions supplied.

Broken rock for gabions have 150 mm minimum size and 300 mm maximum size.

Contractor shall propose the materials suitable for each engineering function, location and type of the works to the Owner for approval.

SETTING

Base Preparation

General

Prior to place gabion, strip the areas from any loose material, trees, organic materials, or deleterious matter. Excavated materials shall be hauled to and disposed of in the disposal area.

The foundation shall be excavated and back filled with approved materials to the depth and elevations shown on the approved drawings. Prior to the starting of excavation, the Contractor shall submit for the Owner's approval a detail drawings and plan of operation. Backfill shall be placed within the limits of the excavations or to the line and grades shown on the approved drawing or as directed by the Owner.

The surface upon which gabions are to be laid shall be thoroughly compacted and trimmed to the specified level or shape.

Placing on River Bed

The gabions shall be placed on horizontal surfaces, with their bottom and sides slightly embedded into the rock. Excavations for this embedment shall be carried out in accordance with the approved drawing or as directed by the Owner.

Placing on Excavation Slope

The surface slope of the excavation which will be protected by gabions shall be trimmed to an even grade and followed by the laying of geotextile as shown on the approved drawing or as directed by the Owner.

Existing voids shall be completely filled with small rock pieces. Gabions shall be secured to the surface slope by 3 m long steel bars 25 mm in diameter, driven through the gabions and set into the ground at 2 m centers.

Gabions shall be constructed to the shapes and dimension as shown on the Drawing or instructed by the Engineer. Gabions as constructed shall be within a tolerance of + 5 % on the height or width directed and + 3 % on the length directed.

The alignment of the gabions shall be correct within a tolerance of 100 mm of the directed alignment and the level of any course of gabion shall be correct to within a tolerance of 50 mm of the instructed level. In addition adjacent gabions shall not vary by more than 25 mm in line and/or level from each other.

All edges of the standard gabions including end panels and the diaphragms, if any, shall be mechanically selvedged in such a way as to prevent reveling of the mesh and to develop the full strength of the mesh.

Adjacent gabions shall be stitched together with lacing wire along touching edges.

Gabions boxes shall be laid broken bond throughout to avoid continuous joins both horizontally and vertically.

The sides shall be packed first in the form of a wall, using the largest pieces, with the majority placed as headers with broken joints to present a neat outside face. The interior of the gabion shall be hand packed with smaller pieces and the top layers shall be finished off with larger pieces. The whole interior and top layers shall be packed tightly and hammer into place.

Gabion materials shall be protected against damage. Damaged materials shall be repaired or replaced to the satisfaction of the Owner.

After placing a number of dip galvanized gabions, casings into position, they shall be linked by seam wires connecting their corners and filled with rock fragments. Subsequent gabions shall be tightly sewn to those already placed, the various layers of gabions shall also be connected to each other. Connections shall be made between full gabions; as well as between full and empty gabions. The filling materials shall be introduced into each gabion by hand, and placed so as to fill it as completely as possible.

GEOTEXTILE

MATERIAL

The geotextile shall be sufficiently dense to prevent piping of fine particles, shall be porous enough to prevent back pressure build‑up and shall be thick enough to contain any waterflow within it and thus prevent soil erosion causes surface instability.

The geotextile fabric shall meet the fully following requirements. If required, a sample of 1 m² shall be supplied to the Owner for approval and retention for purposes of comparative testing against materials randomly sampled from the site. The requirements are as follows:

The geotextile fabric shall be of the non‑woven type and comprises of continuous filaments of polypropylene polymer mechanically bonded to a homogeneous sheet. Geotextile manufactured from staple or waste or recycled fibers shall not be accepted.

The manufacturer is required to certify that the quality of polymer used in the manufacture of the geotextile is such that retention of at least 80% of original tensile strength values after 3 months continuous exposure to natural sunlight in Asian conditions will be achieved.

Fibers used in the manufacture of the geotextile shall be resistant to long term contact with damp cementitious substrates or acid or alkali leachate solutions in the pH range 2‑13.

Where the geotextile is required as filter in silty soil conditions, the minimum porosity of geotextile shall be > 80 %.

Each roll of geotextile supplied to the site shall have its grade and protection batch number clearly printed on the outer wrapper and at regular intervals along the length of each sheet to facilitate visual on‑site quality control.

REQUIRED MECHANICAL AND HYDRAULIC PROPERTIES

The geo-textile shall meet the fully following requirements.

TEST TYPE	REQUIREMENT	TEST METHOD

Nominal mass (g/m²)	Min. 325	ISO 9864
Thickness (mm)	Min. 2.9	ISO 9863
Wide width tensile strength (kN/m) (According to ASTM D4595)	Min. 24	ISO 10319
Minimum tensile elongation () at break % (According to ASTM D4595)	Min. 80/40	ISO 10319
CBR puncture strength (N) (According to DIN 54307)	Min. 3850	ISO 12236
Maximum effective opening size O₉₀ (mm	Max. 0.09	ISO 12956
Permeability under pressure 2 kPa	Min. 3 x 10 ^-3	ISO 11058
Water Flow :
- Vertical 100 mm head (l/m²/s)	Min. 117	ISO 11058
- Horizontal 20 kPa	Min. 16	ISO 12958

STORAGE AND INSTALLATION

The geotextile shall be delivered to site with an outer protective wrapper. Long term site storage shall include additional coverings to protect the geotextile from exposure to the elements.

Installation of the geotextile shall be in accordance with the manufacturer's instructions. If required, the manufacturer's installation requirements shall be made available to the Owner in writing.

Geotextile overlaps shall be sufficient to prevent parting during placement of initial fill and under construction and operating conditions. On soft soils subject to settlement the overlap shall be at least 1.0 m to avoid parting during the settlement process. Alternatively, the geotextile overlap may be heat fused or hand or machine sewn using single or double‑stitch portable sewing machines and appropriate polypropylene or other synthetic thread. In critical applications the seam strength shall be equal or greater them 90% of the tensile strength of the geotextile itself.

The geotextile shall not be subjected to direct construction vehicle traffic and backfill operations shall closely follow laying of the sheet.

After placing a number of geotextile sheets into position, the gabion shall be placed as shown on the drawing and/or as directed by the Owner.

The Contractor shall be responsible for avoiding damage to the geotextile during placement and compaction of the initial fill layer. The capability of the geotextile to resist installation damage shall be considered by the Contractor prior to submission of materials to the Owner for approval.

If required by the Owner, the Contractor shall at no charge excavate down to the geotextile at regular intervals to visually check against construction damage and on completion of the inspection, backfill and re-compacted. Damaged geotextile areas shall be fully exposed and overlaid with an additional layer of geotextile prior to backfilling.

In the event that consistent visible damage to the geotextile is observed, the Contractor shall be obliged per the Owner's instruction to upgrade the quality of geotextile used in subsequent sections of the construction.

INSPECTION AND TESTING

The Contractor shall be responsible for all inspection and testing work as required.

The Owner may, during the course of the work, inspect the various phases of the work at the site for full compliance with all requirements of this specification and the design drawings.

SLOPE STABILIZATION

The contractor shall comply with the requirements of the applicable codes and standards published by the following organizations:

RIPRAP

MATERIAL

The riprap material in relation with their common engineering functions is stone with sound of rock type and the size range of stones shall be 15 - 60 cm.

Contractor shall propose the materials suitable for each engineering function, location and type of the works to the Owner for approval.

Material properties such as mass per unit area, density, hardness and type of rock, shall be determined by the Contractor and submitted to the Owner for approval.

SETTING

Riprap shall be furnished and placed to the lines and grades as shown on drawing or as directed by the Engineer.

Stone of riprap shall be placed over a gravel bedding to produce a dense and stable rock blanket over the surface requiring protection, and shall be constructed within the specified tolerance to the lines and grades as shown on the drawing.

Riprap shall be placed to its full coarse thickness at one operation and in such a manner as to avoid displacing the underlying material.

The larger stones shall be well distributed, with smaller rock filling the space between them.

The entire mass of stones in their final position shall be roughly graded.

The finished riprap shall be free from objectionable pocket of small stones and cluster of larger stones.

Rearranging of individual stones by mechanical equipment or by hand will be required at the extent necessary to obtain a reasonably well graded distribution of stone sizes.

RUBBLE MASONRY

MATERIAL

The stone for rubble masonry shall be natural or crushed stone.

The stoned used shall be clean and must be washed if necessary in the opinion of the Owner.

Unless otherwise shown on the drawings, stones shall have minimum size not less than 25 cm.

The rubble stone shall be placed with 1:3 cement - mortar after having joints throughly moistened the spaces between the stone and the surface joint shall be filled with 1: 3 cement - mortar.

PLACING

The rubble stone shall be hand - placed with uncoursed close joints to the line and grades as shown on the drawings or as directed by the Owner.

Where the rubble masonry is to be placed on a prepare foundation bed, the bed shall be firm and normal to or in steps normal to the face of the wall, and shall have been approved by Owner's before any stone is placed.

The exposed faces of individual stones shall be parallel to the faces of the walls in which the stones are set.

If a stone is loosened after the mortar has taken initial set, it shall be removed, the mortar cleaned of, and the stone relaid with fresh mortar.

Care shall be taken to prevent the bunging of small stones or stones of the same size.

GABION

MATERIAL

The standard type gabions shall be a flexible hot-dip galvanized gabion with PVC coated of the type and size specified below. It shall be made of wire mesh of type and size as specified in the following:

· The mesh shall be hexagonal woven mesh, the joints formed by twisting each pair of wires through three half turns.

· The size of mesh conforms to standard specification issued by the factory and shall be not greater than 2/3 of the smallest stone filled in the gabion.

· All wire used in the fabrication of the gabions and in the wiring operations during construction shall be galvanized and "Mild Steel Wire", with an average tensile strength of 44 kg/sq.mm.

· The diameter of the wire used in the fabrication of the netting shall be not less than 3.2 mm according to engineering requirements.

The standard gabions shall have the following dimensions:

Sufficient lacing and connecting wire shall be supplied with the gabions for all the wiring operations to be carried out in the construction of the gabion work. The quantity of such wire is estimated to be 8 percent of the gabions supplied.

Broken rock for gabions have 150 mm minimum size and 300 mm maximum size.

Contractor shall propose the materials suitable for each engineering function, location and type of the works to the Owner for approval.

SETTING

Base Preparation

General

Placing on River Bed

Placing on Excavation Slope

Gabions shall be constructed to the shapes and dimension as shown on the Drawing or instructed by the Engineer. Gabions as constructed shall be within a tolerance of + 5 % on the height or width directed and + 3 % on the length directed.

All edges of the standard gabions including end panels and the diaphragms, if any, shall be mechanically selvedged in such a way as to prevent reveling of the mesh and to develop the full strength of the mesh.

Adjacent gabions shall be stitched together with lacing wire along touching edges.

Gabions boxes shall be laid broken bond throughout to avoid continuous joins both horizontally and vertically.

Gabion materials shall be protected against damage. Damaged materials shall be repaired or replaced to the satisfaction of the Owner.

GEOTEXTILE

MATERIAL

The geotextile shall be sufficiently dense to prevent piping of fine particles, shall be porous enough to prevent back pressure build‑up and shall be thick enough to contain any waterflow within it and thus prevent soil erosion causes surface instability.

The geotextile fabric shall meet the fully following requirements. If required, a sample of 1 m2 shall be supplied to the Owner for approval and retention for purposes of comparative testing against materials randomly sampled from the site. The requirements are as follows:

The geotextile fabric shall be of the non‑woven type and comprises of continuous filaments of polypropylene polymer mechanically bonded to a homogeneous sheet. Geotextile manufactured from staple or waste or recycled fibers shall not be accepted.

The manufacturer is required to certify that the quality of polymer used in the manufacture of the geotextile is such that retention of at least 80% of original tensile strength values after 3 months continuous exposure to natural sunlight in Asian conditions will be achieved.

Fibers used in the manufacture of the geotextile shall be resistant to long term contact with damp cementitious substrates or acid or alkali leachate solutions in the pH range 2‑13.

Where the geotextile is required as filter in silty soil conditions, the minimum porosity of geotextile shall be > 80 %.

Each roll of geotextile supplied to the site shall have its grade and protection batch number clearly printed on the outer wrapper and at regular intervals along the length of each sheet to facilitate visual on‑site quality control.

REQUIRED MECHANICAL AND HYDRAULIC PROPERTIES

STORAGE AND INSTALLATION

The geotextile shall be delivered to site with an outer protective wrapper. Long term site storage shall include additional coverings to protect the geotextile from exposure to the elements.

Installation of the geotextile shall be in accordance with the manufacturer's instructions. If required, the manufacturer's installation requirements shall be made available to the Owner in writing.

The geotextile shall not be subjected to direct construction vehicle traffic and backfill operations shall closely follow laying of the sheet.

After placing a number of geotextile sheets into position, the gabion shall be placed as shown on the drawing and/or as directed by the Owner.

The Contractor shall be responsible for avoiding damage to the geotextile during placement and compaction of the initial fill layer. The capability of the geotextile to resist installation damage shall be considered by the Contractor prior to submission of materials to the Owner for approval.

In the event that consistent visible damage to the geotextile is observed, the Contractor shall be obliged per the Owner's instruction to upgrade the quality of geotextile used in subsequent sections of the construction.

INSPECTION AND TESTING

The Contractor shall be responsible for all inspection and testing work as required.

The Owner may, during the course of the work, inspect the various phases of the work at the site for full compliance with all requirements of this specification and the design drawings.

Any work failing to meet the specified requirements, shall be rectified or replace by the Contractor at his expense with no cost to the Owner.

Artikel Terkait

The geotextile fabric shall meet the fully following requirements. If required, a sample of 1 m² shall be supplied to the Owner for approval and retention for purposes of comparative testing against materials randomly sampled from the site. The requirements are as follows: