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3. 2 EXCAVATIONS STOP WORK !!!

4. 3 Regulations OSH Standards Rule 1410 –Construction Safety OSH Standards Rule 1413-Excavation 29 CFR 1926 Sub Part P - Excavation

5. 4 AGENDA Introduction Terminologies Excavation Hazards General Requirements Prior to Excavation Soil Testing Excavation Safety Principles Maximum Allowable Slopes Methods of Excavation Protection OSH Requirements Contributory Factors in Excavation Collapse Excavation Safety Inspection Protection System Equipment & Handtools Heavy Equipment Operator & Spotter Strategies in Implementation of Excavation Activities

6. 5 INTRODUCTION Excavation is always important part of the construction works & mining, i.e, excavation of building & bridge foundations, trenching for buried pipelines & electrical poles, tunneling, etc. Strategic plan should be tabled & implemented while engage for this work. Accidents due to cave-in occur for excavations which are not shored or otherwise supported. Even rock that looks solid from a cursory inspection can collapse w/o warning. The sides of an excavation may need to be suitably shored, benched or sloped back to a safe angle of repose, depth and soil classification.

7. 6 INTRODUCTION (CONT) Other types of excavation accidents are caused by contact w/ above & under ground pipes and cables, by falls of equipment and person, by persons being struck by excavating equipment, and by hazardous atmosphere.

8. 7 INTRODUCTION (CONT) TYPICAL EXCAVATION SITE

9. 8 Typical Excavation Sites

10. 9 Excavation Hazards – Surface encumbrances – Utilities – Access/Egress – Vehicle traffic – Falling loads – Mobile equipment – Hazardous atmospheres – Water accumulation – Adjacent structures – Loose rock or soil – Falls – Cave-in

11. 10 GENERAL REQUIREMENTS PRIOR TO EXCAVATION Carry out joint site safety inspection with client / owner, consultant & company representatives. Identify & locate underground facilities / utilities, i.e., water / oil / gas pipelines, electric powerlines, telephone lines, sanitary sewer lines. Municipal Permit Requirements – Excavation Plan – Verify existing utilities – Refer to as built plans – Emergency / Contingency Plan – Public safety Proximity of adjacent structures Weather & moisture conditions Sources of the vibrations Adjacent road footpaths Method of excavation Other possible considerations

12. 11 Surface Encumbrances Need to be removed or supported e.g. fencing, piping, structure, materials

13. 12 Utilities Underground Locate prior to digging Certify deactivation Protect, support, or remove

14. 13 Access/Egress Note: Poor housekeeping --- # 1 cause of slips, trips and falls on construction projects – Debris kept cleared from work areas – Mark hazards – Barricade or cover holes Egress provided- - 25’ travel distance - ladders - ramps - stairs

15. 14 Vehicle Traffic Traffic Control Traffic Safety Vests

16. 15 Mobile Equipment Warning system – Barricades – Hand signals – Mechanical signals – Stop logs – Grade away from excavation

17. 16 Hazardous Atmosphere Test @ 4’ if suspected – LEL – Oxygen – CO – H2S – Petroleum – Other toxics

18. 17 Ventilation Displace hazardous gases and vapors Considerations – Heavier than air or lighter than air contaminant – Exhausting or blowing in – Volume/time required to lower concentrations to acceptable levels

19. 18 Water Accumulations Protection from hazards associated with water accumulation – Protection against cave-in – Water removal (pumping) – Run-off protection – Consider temporary shut-off of water lines

20. 19 Adjacent Structures Ensure structure stability – Shoring – Bracing – Underpinning – Or evaluation by P.E.

21. 20 Cave-in Protection from cave-in requires a systematic approach including: – Soil classification – Protective systems – Inspection – Employee training

22. 21 SOIL TESTING Soil testing shall be done by accredited Soil Testing Firm for the following reasons: – soil type – pre-planning – type of sloping / shoring required Compilation of Test Certificate

23. 22 EXCAVATION SAFETY PRINCIPLES

24. 23 SAFETY PRINCIPLES SOIL MECHANICS In trenching and excavation practices, SOIL is defined as any materials removed from the ground to form a hole, trench or cavity for the purpose of working below the earth’s surface.

25. 24 SAFETY PRINCIPLES SOIL MECHANICS Soil Mechanics point of view: 1 foot 500 psf 250 psf 100# 1 foot Figure 1. Forces exerted by a column of soil.

26. 25 SAFETY PRINCIPLES Figure 2. Mechanics of Trench Failure. (2a)(2b) TRENCH FAILURES (2c)(2d) (2e)

27. 26 SAFETY PRINCIPLES

28. 27 SAFETY PRINCIPLES SOIL CLASSIFICATION Stable Rock - natural solid mineral matter that can be excavated with vertical sides and remain intact while exposed. Type A - cohesive soil with unconfined compressive strength of 144 kPa or greater. Examples; clay, silty clay, clay loam, sandy clay, clay loam and silty clay loam and sandy clay loam.

29. 28 SAFETY PRINCIPLES SOIL CLASSIFICATION Type B - cohesive soil with unconfined compressive strength greater than 48 kPa but less than 144 kPa. Examples; angular gravel, silt, silt loam sandy loam Type C - cohesive soil with unconfined compressive strength of 48 kPa or less. Examples; gravel, sand, loamy sand submerged soil

30. 29 SAFETY PRINCIPLES TYPES OF SOIL COLLAPSE General zone of exposure The area where workers are exposed to mass soil/rock movement. Spoil pile slide.

31. 30 SAFETY PRINCIPLES TYPES OF SOIL COLLAPSE Side wall Shear Slough-in (Cave-in) Rotation

32. 31 MAXIMUM ALLOWABLE SLOPES

33. 32 METHODS OF EXCAVATION PROTECTION Sloping - please see table for maximum allowable slopes Benching Shoring / Timbering Sheet Piles Concrete Piles Micro piles Diaphragm Dewatering System

34. 33 OSH REQUIREMENTS

35. 34 OSH REQUIREMENTS GENERAL REQUIREMENTS TRAIN WORKERS

36. 35 OSH REQUIREMENTS GENERAL REQUIREMENTS PERSONAL PROTECTIVE EQUIPMENT (PPE)

37. 36 OSH REQUIREMENTS GENERAL REQUIREMENTS PROTECTION SYSTEMS The excavation or trench must either be sloped or supported as required to comply with OSHS Excavation over 6.6 m deep, protection system must be installed to prevent the movement & collapse of adjacent structure shall be designed by structural engineer & approved by the proper authority.

38. 37 OSH REQUIREMENTS 1/3 depth GENERAL REQUIREMENTS LOCATION OF EXCAVATED MATERIALS AND EQUIPMENT 1/3 depth, 1 m. min.

39. 38 OSH REQUIREMENTS GENERAL REQUIREMENTS PUBLIC PROTECTION & TRAFFIC CONTROL Traffic around the site must be controlled, and barricaded, signs and/or flag persons used as needed to control both vehicular and pedestrian traffic.

40. 39 OSH REQUIREMENTS GENERAL REQUIREMENTS PROVISION FOR ACCESS/ EGRESS A ladder must be located within 25 ft or 8m of a worker’s working position. d>1 m 0.83 m

41. 40 OSH REQUIREMENTS GENERAL REQUIREMENTS d>2 m 1.0 m PROVISION FOR BARRICADES

42. 41 OSH REQUIREMENTS GENERAL REQUIREMENTS EXPERIENCED SUPERVISOR An experienced and trained worker is designated to directly supervise each excavation project. - sloping and benching - shoring requirements - emergency rescue procedures.

43. 42 OSH REQUIREMENTS GENERAL REQUIREMENTS SITE INSPECTION Every part of an excavation over 2 m deep where workers work shall be inspected. A competent person shall conduct daily inspections of excavations, adjacent areas, and protective systems for evidence of a situation that could result to an accident.

44. 43 CONTRIBUTARY FACTORS IN EXCAVATION COLLAPSE Water (i.e., rain, natural ground water, near the water sources)! Improper sloping technique! improper impoundment of excavated soil! Wrong parking of heavy equipment, machines & vehicles! Improper barricade, light, sign, etc. No regular monitoring or inspection! No adequate training!

45. 44 Simple Slope Type A - 3/4:1 Type B - 1:1 Type C - 1½ :1

46. 45 Benching Type A Type B (cohesive soil) Type C NA

47. 46 Shoring

48. 47 Timber Shoring

49. 48 Aluminum Shoring

50. 49 Shields (Trench Boxes)

51. 50 Protective Systems Removal – Employees clear of area under shields during removal – Shoring removed from the bottom up, SLOWLY! – Backfill with removal

52. 51 SITE INSPECTION EXCAVATION SAFETY INSPECTION uInspection shall be conducted prior during after each hazard changing event. uDaily Inspection shall be conducted on excavations adjacent areas protective systems for possible cave-ins failure of protective systems hazardous atmospheres other hazardous conditions

53. 52 SITE INSPECTION EXCAVATION SAFETY INSPECTION SAMPLE DAILY INSPECTION uSurface Conditions Cracks or Cracking Spoil piles set back 2’ from edge No equipment or material near edge No standing water in excavation No sources of vibration uBanks and Sides of Slope or Bench Cracks or Cracking Spalling Change in Soil type Slope adequate for soil

54. 53 SITE INSPECTION EXCAVATION SAFETY INSPECTION SAMPLE DAILY INSPECTION uShoring and Shielding In place No leakage on hydraulic cylinders Wedges tight uAccess and Egress Access every 25 feet Stairs, ladders and ramp set properly

55. 54 SITE INSPECTION EXCAVATION SAFETY INSPECTION SAMPLE DAILY INSPECTION uExisting Utilities Support Adequate Loose Materials Utilities identified and protected. uWeather Rain Typhoon, Storm, Wind uPPE Reflectorized vests in vehicular areas Hard hats, steel-toe shoes, etc. being used as specified.

56. 55 PROTECTION SYSTEM EXCAVATION SAFETY INSPECTION uSLOPING AND BENCHING The slope and configuration of sloping and benching system shall be selected and constructed by competent person. uSHORING AND SHIELDING

57. 56 PROTECTION SYSTEM SELECTION OF PROTECTION SYSTEMS Is the excavation more than 3 feet or 1 meter Is the excavation entirely in stable rock Excavation may be made with vertical sides Excavation must be sloped, shored, or shielded Figure A. Preliminary Decisions Is there potential for cave-in? Go to Figure C Go to Figure B NOYES NO YES SHORING OR SHIELDING SELECTED SLOPING SELECTED

58. 57 PROTECTION SYSTEM SELECTION OF PROTECTION SYSTEMS Figure B. Sloping Options Sloping selected as the method of protection Will soil classification be made in accordance with the maximum allowable configurations and slopes, or designs using tabulated data, or design by a registered engineer. Excavation must comply with one of the three options: Option 1 Design using requirements of Soil Classification and requirements of sloping and Benching. Option 2 Designs using other tabulated data Option 3 Design by a registered Professional Engineer. Excavation requires a slope of 1 1/2H and 1V (34 deg.) NOYES

59. 58 PROTECTION SYSTEM SELECTION OF PROTECTION SYSTEMS Figure C. Shoring and Shielding Options Shoring and Shielding selected as the method of protection Soil classification is required when shoring or shielding is used. The excavation must comply with one of the following four options. Option 1 Design using requirements of Soil Classification and requirements of Timber Shoring for Trenches. Option 2 Designs using Manufacturer’s Tabulated Data Option 3 Designs using other tabulated data. Option 4 Design by a registered professional Engineer.

60. 59 EQUIPMENT & HANDTOOLS EQUIPMENT – Backhoe – bulldozer – wheel Loader – Grader – Rock Breaker HANDTOOLS – Shovel – Pickax – Pneumatic hammer – etc.

61. 60 HEAVY EQUIPMENT

62. 61 BACKHOE

63. 62 Back Hoe

64. 63 PNEUMATIC HAMMER

65. 64 EXCAVATION SAFETY What’s wrong with this photo?

66. 65 Thank you