1、OSHA Office of Training and Education1Excavation HazardsCave-ins are the greatest risk Other hazards include: Asphyxiation due to lack of oxygen Inhalation of toxic materials Fire Moving machinery near the edge of the excavation can cause a collapse Accidental severing of underground utility linesOS
2、HA Office of Training and Education2Injury and DeathExcavating is one of the most hazardous construction operationsMost accidents occur in trenches 5-15 feet deepThere is usually no warning before a cave-inOSHA Office of Training and Education3DefinitionsExcavation a man-made cut, cavity, trench, or
3、 depression formed by earth removal.Trench a narrow excavation. The depth is greater than the width, but not wider than 15 feet.Shield - a structure able to withstand a cave-in and protect employeesShoring - a structure that supports the sides of an excavation and protects against cave-insSloping -
4、a technique that employs a specific angle of incline on the sides of the excavation. The angle varies based on assessment of impacting site factors. OSHA Office of Training and Education4Focus of Training The greatest risk at an excavation How to protect employees from cave-ins Factors that pose a h
5、azard to employees working in excavations The role of a competent person at an excavation siteOSHA Office of Training and Education5 Protection of EmployeesEmployees should be protected from cave-ins by using an adequately designed protective systemProtective systems must be able to resist all expec
6、ted loads to the systemOSHA Office of Training and Education6 Requirements for Protective SystemsA well-designed protective system Correct design of sloping and benching systems Correct design of support systems, shield systems, and other protective systemsPlusAppropriate handling of materials and e
7、quipment PlusAttention to correct installation and removal Equals Protection of employees at excavationsOSHA Office of Training and Education7Design of Protective SystemsThe employer shall select and construct : slopes and configurations of sloping and benching systems support systems, shield system
8、s, and other protective systemsShield - can be permanent or portable. Also known as trench box or trench shield.Shoring - such as metal hydraulic, mechanical or timber shoring system that supports the sides Sloping - form sides of an excavation that are inclined away from the excavationOSHA Office o
9、f Training and Education8Protect Employees Exposed to Potential Cave-inslSlope or bench the sides of the excavation,lSupport the sides of the excavation, or lPlace a shield between the side of the excavation and the work areaOSHA Office of Training and Education9Cave-in HazardThis excavation has ina
10、dequate support posts and egress accessInadequate protective systemOSHA Office of Training and Education10Inadequate Protective System l This worker is in a trench with no protective system, that is not sloped or benched and has no means of egressOSHA Office of Training and Education11Factors Involv
11、ed in Designing a Protective SystemlSoil classificationlDepth of cutlWater content of soillChanges due to weather and climatelOther operations in the vicinityOSHA Office of Training and Education12ShoringGeneral Provides a framework to work in Uses wales, cross braces and uprights Supports excavatio
12、n wallsOSHA tables provide shoring data Must know soil type Must know depth and width of excavation Must be familiar with the OSHA TablesOSHA Office of Training and Education13Trench ShieldA trench shield was built around this work areaOSHA Office of Training and Education14Hydraulic Trench SupportU
13、sing hydraulic jacks the operator can easily drop the system into the holeOnce in place, hydraulic pressure is increased to keep the forms in placeTrench pins are installed in case of hydraulic failureOSHA Office of Training and Education15Materials and EquipmentEquipment used for protective systems
14、 must not have damage or defects that impair function. If equipment is damaged, the competent person must examine it to see if it is suitable for continued use. If not suitable, remove it from service until a professional engineer approves it for use.OSHA Office of Training and Education16Protection
15、 from Vehicles Install barricades Hand/mechanical signals Stop logs Grade soil away from excavation Fence or barricade trenches left overnightOSHA Office of Training and Education17Hazardous ConditionsThe weight and vibrations of the crane make this a very hazardous condition. They should not be wor
16、king under this crane.OSHA Office of Training and Education18SpoilsDont place spoils within 2 feet from edge of excavationMeasure from nearest part of the spoil to the excavation edge Place spoils so rainwater runs away from the excavationPlace spoil well away from the excavationOSHA Office of Train
17、ing and Education19Other Excavation HazardsWater accumulationOxygen deficiencyToxic fumesAccess/EgressFallsMobile equipmentOSHA Office of Training and Education20Water is HazardousWhen water is present in an excavation it is extremely hazardous to enterNote that these workers are not wearing hardhat
18、s to protect them from materials falling into the trenchOSHA Office of Training and Education21Water = Cave-in HazardThese workers must be protected from cave-in. Note the water in the bottom of the trench. This is a very hazardous condition!OSHA Office of Training and Education22Hazardous Atmospher
19、eTest excavations more than 4 feet before an employee enters the excavation for: Oxygen deficiency High combustible gas concentration High levels of other hazardous substancesOSHA Office of Training and Education23Means of EgressA stairway, ladder, or ramp must be present in excavations that are 4 o
20、r more feet deep, and within 25 feet of the employeesThis ladder does not meet the requirements of the standardThe ladder should extend 3 feet above the excavationOSHA Office of Training and Education24Access and EgressThese two ladders which are lashed together are not an adequate means of egressTh
21、e ladder should extend 3 feet above the top of the excavationOSHA Office of Training and Education25Protection from Falls, Falling Loads, and Mobile EquipmentInstall barricadesUse hand / mechanical signalsGrade soil away from excavationFence or barricade trenches left overnightUse a flagger when sig
22、ns, signals and barricades are not enough protectionOSHA Office of Training and Education26 Competent Person Must have had specific training in and be knowledgeable about: Soils classification The use of protective systems The requirements of the standardMust be capable of identifying hazards, and a
23、uthorized to immediately eliminate hazardsOSHA Office of Training and Education27Inspections of ExcavationsA competent person must make daily inspections of excavations, areas around them and protective systems: Before work starts and as needed, After rainstorms, high winds or other occurrence which
24、 may increase hazards, and When you can reasonably anticipate an employee will be exposed to hazards.OSHA Office of Training and Education28Inspections of ExcavationsIf the competent person finds evidence of a possible cave-in, indications of failure of protective systems, hazardous atmospheres, or
25、other hazardous conditions: Exposed employees must be removed from the hazardous area Employees may not return until the necessary precautions have been takenOSHA Office of Training and Education29Site Evaluation PlanningBefore beginning excavation: Evaluate soil conditions Construct protective syst
26、ems Test for low oxygen, hazardous fumes and toxic gases Provide safe in and out access Contact utilities Determine the safety equipment neededFissureOSHA Office of Training and Education30Summary The greatest risk in an excavation is a cave-in. Employees can be protected through sloping, shielding, and shoring the excavation. A competent person is responsible to inspect the excavation. Other excavation hazards include water accumulation, oxygen deficiency, toxic fumes, falls, and mobile equipment.
