(4E) Work Supervision
Presentation for LRN Training
Hom Nath Lamsal, LRN Construction Specialist
August 2015
Rural Access Programme Development through access 1 Module Contents
Method statements Supervision checklists Site inspection record books Site instructions Safety
Rural Access Programme Development through access 2 METHOD STATEMENTS
Rural Access Programme Development through access 3 Method Statements
Define the way in which particular work tasks must be carried out in accordance with specifications and drawings Outline the risks involved in carrying out a particular work task and provide a step-by- step guide to carrying out the work safely Detail the labour, materials, tools, and equipment requirements for a work task Ensures that all actors involved have a clear understanding of the standard and safe process to execute a work item
Rural Access Programme Development through access 4 Example Method Statement Work Item: Construction of a gabion retaining wall Procedure: Setting out of wall as per approved Working/ construction drawing Earthwork commencement only after acceptance of setting out by IoW/ARE/RE Excavation to be confined within the line of excavation as defined in the drawing, no over excavation Excavated material kept aside, no throw Foundation shoring, bracing (if required) Checking and approval of foundation: level, inward slope, soil type. Practice of trimming down outer side of trench has been noticed abundantly
Rural Access Programme Development through access 5 Example Method Statement Contd.
Rural Access Programme Development through access 6 Example Method Statement Contd. Procedure Contd.: Assembling of gabion boxes in open flat hard space (not inside the foundation trench), lacing of sides and diaphragms Placing of gabion boxes in foundation trench, lacing of adjacent gabion boxes to each other (no twisting of selvage wires) Stone masonry work (not dumping) in simultaneous layers in all compartments of gabion boxes (3 layers in 1 m and 2 in 0.5 m deep) Corner stones and staggered vertical joints in courses of stone
Rural Access Programme Development through access 7 Example Method Statement Contd. Procedure Contd.: Horizontal bracing in each layers from each compartments of boxes looped two adjoining meshes Upper face of gabion box if not covered will have vertical bracing as above @ 2 ties/ sq.m. Compartments are filled 50 mm above the box top to allow subsequent settlement All hinges of gabion box lids will face outer face of wall
Rural Access Programme Development through access 8 Example Method Statement Contd.
Rural Access Programme Development through access 9 Example Method Statement Contd.
Rural Access Programme Development through access 10 Example Method Statement Contd.
Rural Access Programme Development through access 11 Example Method Statement Contd. Procedure Contd.: Supervising staff to inspect every layers prior to proceeding with upper layer construction Lids of gabion boxes will be tied to all diaphragms Lids then stretched to their selvage boarders and laced Simultaneous backfilling behind the gabion wall @ 15 cm layers with watering and compaction as the wall progresses Site clearance
Rural Access Programme Development through access 12 Example Method Statement Contd. Requirements Labour: Skilled labour, unskilled labour Material: Gabion boxes / mattress, stone, binding wires Instruments/Tools: Auto level, pipe level, pegs, string, measuring tape (30 / 5 m), pickaxe, shovel, Doko, wheel barrow, rope, dressing hammer, plumb bob, pliers, binding tool, rammer, wire cutter
Rural Access Programme Development through access 13 Example Method Statement Contd. Health and Safety: Personal Protective Equipment (PPE): All workers must wear a safety helmet, high visibility vest, gloves, and safety footwear at all times Work sign boards and barricades need to be in place Site rules must be adhered to Clear, and safe, access ways must be in place Work conducted at heights must be done by workers with appropriate training Workers must have access to a first aid facility at all times
Rural Access Programme Development through access 14 Example Method Statement Contd.
Gabion basket with only 3 sides complete
Rural Access Programme Development through access 15 Key Notes on Construction of Masonry Wall (Dry, Mortared, Gabion, Composite) Mostly used – random rubble masonry partially coursed Stone to be sound/hard and angular in shape, free from shakes/flaws/cracks Sp. gravity not less than 2.5 85% of stone to be of size > 0.01 m3 Shall not absorb water more than 5% (in 24 hrs. immersion)
Rural Access Programme Development through access 16 Key Notes on Construction of Masonry Wall Contd. (Dry, Mortared, Gabion, Composite) Spalls/chips and voids not to occupy >20% volume of wall in dry masonry Spalls and mortar not to occupy > 30% of volume of wall in mortared masonry Stone to be hammer dressed on face, sides and beds Vertical joints in every layer to be staggered and horizontal lapping not < 10 cm
Rural Access Programme Development through access 17 Key Notes on Construction of Masonry Wall Contd. (Dry, Mortared, Gabion, Composite) Bond stone to be provided At least one on every 0.5 m2 exposed face Cross-section (face) to be not < 15cm×15cm A thorough bond stone for wall up to 60 cm th. For thicker walls, two or more bond stones overlapping not < 15cm Plum (vertical) stone to be embedded at 90cm interval to join successive courses
Rural Access Programme Development through access 18 Key Notes on Construction of Masonry Wall Contd. (Dry, Mortared, Gabion, Composite) Foundation is to be excavated at right angle to the face batter. Beds of the stone shall be laid at right angle to the batter. Header stones are to be laid over stretcher stone in consecutive courses (layers). The uppermost layer of dry wall to be laid on edge to keep the stone intact
Rural Access Programme Development through access 19 Quality of Materials and Testing Provisions Stone – visual inspection to ensure hard/sound and free of cracks/shakes Cement – cube test for compressive strength GI Wire – Zinc coating and tensile strength test Gradation, CBR,PI, MDD, OMC for subgrade and pavement layers
Rural Access Programme Development through access 20 SUPERVISION CHECKLISTS
Rural Access Programme Development through access 21 Supervision Checklists A tool for site manager to ensure high standard of site supervision Includes critical activities that needs to be checked Requires collection of evidence, e.g. photos Any changes/variations in the work are noted in the supervision checklists
Rural Access Programme Development through access 22 Sample Supervision Checklist 1 Setting out: SN Description Yes/ No
1 Is the location/chainage of structure correct? 2 Is the setting out work true to line?
3 Is the setting out work true to level?
4 Are the excavation lines true to line?
Rural Access Programme Development through access 23 Sample Supervision Checklist 2 Excavation and construction of Foundations: SN Description Yes/ No
1 Is the foundation work true to line?
2 Is the foundation work true to level? 3 Is the slope of the foundation platform correct? 4 Is there any side casting of spoils? 5 Is the foundation soil appropriate?
Rural Access Programme Development through access 24 Sample Supervision Checklist 3 Production, placing, and filling of gabions:
SN Description Yes/ No 1 Are the gabion boxes properly laced? 2 Are the gabion boxes properly braced? 3 Is the stone quality of the right standard? 4 Are the corner stones correctly placed? 5 Are the vertical joints alternating?
Rural Access Programme Development through access 25 Sample Supervision Checklist 4 Other works: SN Description Yes/ No 1 Are safety measures complied with at all times? 2 Are there adequate temporary works in place? 3 Are there any works to be measured which will covered up? 4 Are there any changes/variations required compared to the drawings?
Rural Access Programme Development through access 26 Rectification of Works
If defects are found while inspecting the works, necessary instructions are to be issued for rectification Different procedures for RBG and contractor works to issue instructions in case of non-compliance with the specifications and drawings
Rural Access Programme Development through access 27 SITE INSPECTION RECORD BOOKS
Rural Access Programme Development through access 28 Site Inspection Record Book
Daily record of site activities, also called Daily Site Diary Maintained by site supervisor (normally lowest tier of supervision), but reviewed and signed-off regularly by the RE Used to maintain a constantly up to date record of the site, and the works
Rural Access Programme Development through access 29 Site Inspection Record Book Contd. Site Inspection Record Book must include: Site weather conditions Details of on-going, and planned, activities No. of labours on site No., and type, of equipment on site Type and amount of materials on site Details of any work stoppages Details of any verbal direction given on site Record of monitoring/supervision visits and advice from other project personnel (ARE, RE, DTL, DC, DDC, DTO, etc.) Rural Access Programme Development through access 30 Example Site Inspection Record Book
Daily Site Diary
Weather consdition: Date: Road Name: Package no. Contractor/ RMUC: Activities: SN Location Description Labour (no.) Material Equipment
Comments:
Recorded by: Siganture: Name: Designation:
Rural Access Programme Development through access 31 SITE INSTRUCTIONS
Rural Access Programme Development through access 32 Site Instructions A written instruction given to contractor, RMUC, or RBG in order to improve site works Must be signed by recipient and issuer Site instruction is issued to: Rectify any defects Improve work methodology Change order if any Improve safety aspects
Rural Access Programme Development through access 33 Sample Site Instruction SITE INSTRUCTION NAME OF ROAD Ramaghat Singhasen (RS2) CORRIDOR: Contract ID No. DDC/ 071/72/ 069DR12 INSTRUCTION NUMBER 1
Name of Contractor: Rastra Sewa Nirman Sewa DATE OF ISSUE 2-Mar-11
LOCATION CH 5+400 ISSUED BY Muga Lal Yadav / IoW *geotextile laid not on back of wall, instead placed in between the gabion boxes of 3rd layer *stones are simply packed in mid of two gabion boxes, the width of REASON FOR ISSUE filled is approx. 1.3 m *stones in 3rd layer of gabion boxes are not tightly packed *do not meet specification of laying of geotextile & packing of boulders * Dismantle three 2x1x1 gabion boxes and take out geotextile from underneath of boxes INSTRUCTION DETAILS *Re filled same boxes with proper packing, tightly. * Placed and filled one additional boxes of size 1.5x1x1 in gap, where dry stone were packed earlier. STATE OF WORKS AT TIME OF ISSUE (a) Not started
(b) In Progress 3rd layer of gabion boxes just completed
(c) Completed
(d) Other
EFFECT ON WORKS
(a) None (b) Remobilisation of RBG /SBG (c) Construction Materials (e.g. stones, Gabion boxes * three boxes of size 2 x 1 x 1 are to re used etc.) delivered / Received at * one box of size 1.5 x 1 x 1 is to be bring from Purchha store site Delays to dismantle three gabion boxes of 2 x 1 x 1 and to re- fill (d) Delays or disruption the boxes (e) Other REMARKS (If any drawing or others)
Contractor's worker told that they do not know about ' how to use geotextile'. This is the first they used and placed it underneath and in between of boxes to avoid any possible theft.
ISSUED BY SIGNATURE ……………….
………… RECEIVED BY SIGNATURE ….. DISTRIBUTION TO: Contractor, DTO, DTA
Rural Access Programme Development through access 34 SAFETY
Rural Access Programme Development through access 35 Definitions Hazard: Anything with the potential to damage, harm, or cause adverse health effects under certain work conditions Risk: The probability that a person will be harmed or experience an adverse health effect if exposed to a hazard Accident: A physical or mental injury following an exposure to hazards
Rural Access Programme Development through access 36 Site Safety Safety is the control of recognised hazards to attain an acceptable level of risk and reduce accidents Key elements: PPE First aid Site supervision Method statements Training Commitment from all workers at all levels
Rural Access Programme Development through access 37 Hazard Control Hierarchy
1. Elimination or substitution 2. Engineering controls 3. Safety devices 4. Warning systems 5. Administrative controls
Rural Access Programme Development through access 38 Identification and Mitigation of Hazards Identify steps involved in works Identify hazards related to each step Apply hazard control hierarchy Determine methods to mitigate against remaining hazards Ensure that everyone is aware of the hazards and the relevant mitigation measures
Rural Access Programme Development through access 39 Improving Site Safety
Everyone is responsible No matter how many times you have conducted a particular task make sure to review the method statement and assess the hazards before starting Use PPE – not a choice Avoid unsafe work practices and conditions, and report these to the site supervisor
Rural Access Programme Development through access 40 Site Safety Checklist For site safety officer Circulated by TMO in English and Nepali Covers all aspects of site safety, including: PPE First aid Provisions for public access Protection from falling debris
Rural Access Programme Development through access 41 END
Rural Access Programme Development through access 42