This article is about PROCEDURE/METHOD STATEMENT FOR EARTHWORK and focusing to the engineers, technicians and supervisors. You will find lot of documents related to this article. Just navigate our website www.paktechpoint.com and find more articles. Please! Do not forget to subscribe our You tube channel also. Thanks in Advance.
PLEASE SUBSCRIBE OUR PAKTECHPOINT YOUTUBE CHANNEL
PROCEDURE/METHOD STATEMENT FOR EARTHWORK-CIVIL
This blog applies to excavation of, and/or filling with topsoil, subsoil, sediments, rock and/or other underlying materials on which the soil is formed. Such as structures footings, grade beams, pits, manholes, retaining walls, catch basins, concrete structure foundations, and any other structure that does not need any special de-watering system and other facilities where the bottoms of foundations are above underground water level for project.
I) SURVEY OF SITE
a) Verify the detail of excavation according to the latest Approved for Construction (IFC) drawings before start of the work. Conduct a survey. verify coordinates and mark the location and the limits of the area to be excavated. Allowance should be provided to have enough working space between the foundation to be constructed and the outer edge of the bottom of the excavation for the personnel and forms, bracing and supports to be installed. In marking the excavation limits, consideration should also be given for additional area to accommodate side slopes of the excavation.
b) Detem1ine the depth of the excavation from the existing ground taking reference from the latest AFC drawing. Always for levels bench marks to be followed.
c) Coordinate with other disciplines involved, verify any existing service/utility lines such d) All excavations shall be “flagged’- off at all times. Those deeper than 1.5 meters shall be ”hard baJTicaded” as well.
e) Establish survey elevation control points that fill placement not exceeding 200mm loose layer as required per standard.
2) EXCAVATION OPERATION
a) Set up barricades and signboards around the area to prevent unwanted personnel from entering the excavation site.
b) Rep011 immediately to the company for any unknown underground installation encountered during excavation. Stop work and wait for further instructions in this case.
3) CAREFUL EXCAVATION
a) Use mechanical excavator whenever possible and if the site condition permits. Excavate manually around existing U/G structure or in congested areas here the use of power machines is not possible.
b) When heavy equipment such as backhoe and dump trucks are in use, a trained person shall be assigned to direct the traffic at the place of work and closely monitor the status of excavation work.
c) Barricade shall be placed around the machine operation area.
d) Where the excavation site is close to the existing structures, sufficient shoring and bracing system shall be planned and approved by contractor and then built against the excavation wall to prevent any possible collapse of the excavation slope and also damage to the structures. Where the excavation extends below the foundation of existing adjacent structures well planned and approved measures to protect that structure must be provided.
e) Excavate up to the desired level, width and length as required to conform to the latest
IFC drawing. The vertical tolerance shall be as per specification.
f) If the area does not permit the stockpiling of excavated materials, transport and store the excavated materials to a designated stockpile area. These excavated materials shall be used again as selected fill upon approval of contractor.
g) When the desired bottom elevation is reached, level and compact the ground by using an appropriate machine such as 1 ton roller, jumper or plate compactors up to the required level and density to conform with the Project Specification requirement.
h) Remove and replace with compacted structural fill, any sort of contaminated soil, if any, found at excavation bottom.
i) Over excavation shall be backfilled & compacted properly.
j) Clarify to CSD all excavation works for foundations reaching deeper than Elevation 2.2m MSL where geo textile were laid to be damaged due to excavation.
4) TRENCHING UNDERGROUND PIPING
a) All excavations shall be restored so its surface contour blends in with the surrounding area. Areas of roadways and pavement shall be excavated and restored in accordance with SAES-Q-006 and GI-1021.000
b) If trench de-watering is necessary no construction shall stai1 until the design of the dewatering system has been approved by the Saudi Aramco Representative. Trench de watering system shall be in accordance with SAES-A-114. Dewatering systems shall not discharge into existing sewers or completed sections of new sewers without the approval of the authorities having jurisdiction on the maintenance of the sewer systems. It shall also not discharge into open surface areas without the approval of the authorities having jurisdiction on the maintenance of the area.
c) The bottom of the trench shall be dry or sufficient drained so that there is no standing water before the support and bedding layers are placed and compacted. The bedding layer must be sufficiently drained so that there is no standing water on the bedding layer before the pipe is installed.
d) At the end of every work shift, personal performing the pipe installation shall ensure that the pipe ends are capped to prevent the egress of foreign material, and the piping is anchored to prevent floatation.
f) The depth of the trench shall be dug deep enough to provide a minimum ground cover above the top of the pipe, as required in Table 3 of this Standard, and a ground bed of at least 150 mm in depth below the bottom of the pipe.
g) The width of the trench should be wide enough to allow room for jointing, but in any case not less than shown in Table 2 of this Standard.
5) BACKFILL AND COMPACTION
Backfilling will be carried out by following the norms as set out hereunder column:
a) Backfilling will be done only after the curing time for the cast-in-situ concrete is completed, surface preparation and water proofing done to concrete below ground level.
b) Backfilling will be done using appropriate material or selected granular material when required, in unifonn horizontal layers not exceeding 300mm loose thickness. Each layer will be compacted to a dry density, depending on the area of working. When granular material is used, it will be compacted to a firm and stable condition using an appropriate compacting device. Backfill material shall conform to relevant Project Spec.
c) Backfilling will proceed symmetrically around the structure, whenever possible to do so.
d) Where earth pressure likely to act upon the structure, the backfilling will start only after the concrete has achieved 80% of the characteristic strength. ln no case the backfilling will be done before the concrete is cured for seven days.
e) Excavation sides slopes will be stepped with each layer to avoid wedging of the fill material between the structure and side walls.
f) Backfill around concrete structure not to be stai1ed until concrete repair works are completed and specified coatings are applied and fully cured on the concrete surface.
g) The water for the compaction will be sprayed uni form ly. If required, the fill material will be ploughed to uniform water content before compacting. If drying is required, the same will be done by way of natural drying. In case additional dry material is added for drying, care will be taken to sec that the layer thickness does not exceed as specified.
6. SAFETY CONTROL
1) Contractor Safety Supervisor shall carry out the safety site inspections to ensure that safety requirements laid out in the safe work plan are being followed during and after the excavation work. Safety Manager/ Supervisor shall review Safety Action Plan and secure Work Permit if necessary prior to start of any activities job safe analysis will be strictly followed.
a) Barricading of excavation and “swing” areas of equipment shall be checked prior to the b) Equipment, tools and materials inspection. All equipment for excavation works shall have
to be inspected by Safety Manager/ Supervisor prior to forwarding to contractor Safety Department inspection prior to its use at site to ensure safe worthiness at work. The compactors likewise shall have to be checked by Safety Manager/ Supervisor prior to their use on site and during the execution of work. The inspection Reports shall be kept for record.
c) Prior to work commencing, a Risk Assessment shall be produced by the supervisor. Review and comments to be generated by contractor civil supervisor and safety supervisor to carry through safe practice.
d) All persons involved in the activities including members of the labor force shall be suitably trained.
e) Persons involved in Excavation work shall be provided with and use the necessary PPE and as a standard each person shall wear a Safety Helmet and Safety footwear. The requirement for additional PPE shall be identified in the Risk Assessment and may include the use of the following:
• Eye protection.
• Hand Protection.
• Dust masks.
• Reflective jackets if working in the vicinity of moving traffic.
• And any other necessary PPE
Note: The issue and use of PPE is the final step in protecting people and must not be see as the only safety control method. Risks must be reduced to the smallest amount possible and the PPE is the ‘back up’ equipment.
2) Hazardous substances likely to be used during civil work i.e. concrete, bitumen (paving work), black coal tar paint for concrete foundations, lubricants etc shall be used safely in accordance with the information from a Material Safety Data Sheet (MSDS).
3) The relevant safety information including PPE, First aid, Fire prevention, Spillage control etc shall be extracted from the detailed MSDS and a brief MSDS made covering the key points. This information shall be communicated via tool box talks to all persons who are likely to be exposed to the substances and in addition a copy of the MSDS provided to the site nurse or nominated first aider.
4) The brief MSDS shall be posted in the working area were the substance is in use for all persons to be reminded of the safe working requirements.
5) All plant and equipment involved in the work shall be operated by suitably trained and licensed personnel as per Contractors, Companys and local requirements. Any lifting equipment to be used during the work shall have had 3rd party inspections and posses’ up to date ce11ificates etc. In addition, the equipment shall be inspected by Contractor and a sticker affixed to the inside of the windshield to denote current inspection. Associated lifting equipment i.e. slings, chains etc and electrical or hydraulic tools used during the work will be inspected and color coded in accordance with Contractors color coding procedure.
6) All plant and equipment in operation including cranes shall be controlled by a trained signal man wearing a high visibility reflective jacket and operators shall only take direction from the nominated signalman. A site survey shall be carried out to identify any overhead services i.e. electric cables. supply pipes etc and these shall be protected with goal posts and warning signs with the signalman in full attendance when plant and equipment pass under or work close to these overhead services.
7) Prior to any excavation work commencing suitable measure shall be taken to identify any existing underground services and shall include contact with the Company, a study of any available site layouts, the use of a locater and digging of trial holes by hand. Once these have been identified they shall be clearly marked in addition, the requirement of a permit to work will need to be established depending on site conditions and Company requirements especially if the excavation can effect or be effected by any existing ‘live services’ and or is classed as a confined space. For confined space working suitable rescue equipment must be available with trained rescue personnel on stand by.
2) Industry Codes and Standards
American Society for Testing and Materials
• ASTM C 136 Sieve Analysis of Fine and Coarse Aggregates
• ASTM D422 Particle-Size Analysis of Soils
• ASTM D 1140 Standard Test Methods for Amount of Material in Soils Finer than the No. 200 (75-um) Sieve
• ASTM D1556 Standard Test Method for Density and Unit Weight of Soil in Place by the Sand-Cone Method
• ASTM Dl557 Laboratory Compaction Characteristics of Soil Using Modified Effort 56,000 ft-lbf/ft3 (2700 KN-M/M3)
• ASTM D2167 Standard Test Method for Density and Unit Weight of Soil in Place by the Rubber Balloon Method
• ASTM D2487 Classification of Soils for Engineering Purposes
• ASTM D2937 Standard Test Method for Density of Soil in Place by the Drive-Cylinder Method
• ASTM D4253 Maximum Index Density and Unit Weight of Soils Using a Vibratory Table
• ASTM D4254 Minimum Index Density and Unit Weight of Soils and Calculation of Relative Density
• ASTM D4318 Liquid Limit, Plastic Limit and Plasticity Index of Soils Test
• ASTM D6938 Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)
PIP CVS02100 Site Preparation, Excavation, and Backfill Specification