Working in excavations

You are exposed to many hazards during a construction work day. If you work in excavations, the chief hazard is the danger of cave-ins. 

Ever have to probe for and diffuse a land mine Most people can happily say no. But for construction workers, probing for midergromid utilities, or working in excavations with rmder-ground utilities exposed, the resemblance can be close. 

Responding to a complaint of potentially unsafe conditions at a building under construction in Massachusetts, OSHA inspectors found that employees of a general contractor, and its concrete subcontractor, were working in excavations up to 14 feet deep that lacked protection against a collapse of their sidewalls. 

Employees will not work in excavations where water has accumulated, unless measures have been taken to remove the water from the... 

Excavation work is an essential part of the construction process and one of the most hazardous. Building foundations and the instaiiation of drainage, sewage and other services require trenches to be excavated. Because it is a hazardous operation several people are killed or seriously injured each year whilst working in excavations. Many are killed or injured by excavation wall collapses and falls of materials, others by contact with buried services. Excavation work has to be properly planned, managed, supervised and carried out to prevent accidents and ill health to workers. 

A recent survey of accidents has shown that there are on average seven fatalities each year in excavation work. Over a five year period, the survey showed that fatal and major injuries to workers, who were working in excavations, were caused by the following events ... 

There are about seven deaths each year due to work in excavations and these are often related to the composition and structure of the soil which forms the walls of the excavation. Many types of soil, such as clays, are self-supporting but others, such as sands and gravel, are not. The walls of excavations can collapse without any warning resulting in death or serious injury. Many such accidents occur in shallow workings. It is important to note that, although most of these accidents affect workers, members of the public can also be injured. 

Perform job hazard analyses (JHAs) prior to beginning work to determine potential hazards of the job and their controls such as leaking flammable vapors from equipment that had previously contained hydrocarbons, control of ignition sources, working in excavations, and lockout/tagout. 

Employees shall not work in excavations in which there is accumulated water or in excavations in which water is accumulating unless adequate precautions have been taken to protect employees against the hazards posed by water accumulation. The precautions necessary to protect employees adequately vary with each situation but could include special support or shield systems to protect from cave-ins, water removal to control the level of accumulating water, or use of a safety harness and lifeline. If water is controlled or prevented Irom accumulating by using water removal equipment, the water removal equipment and operations shall be monitored by an authorized person to ensure proper operation. 

Safety hazards are treated in the same manner. For example, workers who work in trenches in clean areas of the site would be covered by the OSHA Excavation and Trenching Standard, Subpart P, 29 CFR 1926. Workers who work in trenches in contaminated areas would fall under both Subpart P and HAZWOPER. Workers who do not work in trenches fall under HAZWOPER only when working in contaminated areas and would not be covered by either standard when working solely in clean areas, provided they are not exposed to safety hazards resulting from hazardous waste operations. 

Je ryl was probably not used in Egypt before Ptolemaic times (87). A. Lucas stated that the mines in the Red Sea hills, which were mentioned by Strabo and Pliny the Elder, were probably the only source of beryl in ancient times (87). In 1817 F. Cailliaud discovered the emerald mines near Mt. Zabara nearly in the same state in which they had been left by the engineers of the Ptolemies. He penetrated into a vast number of excavations and subterraneous canals, some of which are so deep that four hundred men may work in them at once.. .. M. C. himself set about working the mines, and he has presented six pounds of emeralds to Mahommed Ali Pashaw (88). 

Analyses by R. Nasini and R. Grassini indicated that boric acid entered into the composition of the brilliant coral red glazes on the Aretme vases (first century B.C. to first century A.D.) excavated at Arezzo (57, 76). Because of the seal, or impression, on the bottom, these vases were known as terra sigillata ware. Paul Diergart of the research staff of the Royal Porcelain Works in Berlin questioned these analyses, however (58). 

A rtifacts and works of art have been carved from bone and ivory from prehistoric times. The importance of these objects to art historical scholarship is well documented. In recent years, many ivory artifacts have been recovered in excavations in the Ancient Near East from such... 

Uses For work in soft rock, or in hard rock where a shattering effect is not desired also in sand, clay, and earth excavation where the material is a little too hard for blasting powder. Has to a large extent displaced the straight nitroglycerine dynamite. 

EUTRON ACTIVATION ANALYSIS IS A VERY SENSITIVE TECHNIQUE for trace element determinations in various samples. If there are no elements that mutually interfere, the purely instrumental version of this method is often chosen for its established advantages such as accuracy, speed, sensitivity, simultaneous multielement determination, and sample preservation (1). For these reasons, instrumental neutron activation analysis (INAA) was applied to samples taken from a series of metal-working residues excavated at Tel Dan, Israel, from 1985 to 1986. 

Excavation and concrete work in freezing weather can be very expensive and should be avoided. In some instances the construction site may have to be shut down during the winter months. 

A rectangular building foundation is to have dimensions of 18 X 24 m. The bottom of the footings will lie below the water table. To be able to work in dry conditions, it is desired to temporarily lower the water table by at least 2.5 m throughout the area proposed for excavation. 

The quicksilver mines at Almaden in the province of Ciudad Real, Spain, are the richest and most valuable in Europe, normally producing about half the world s supply of the metal. They were worked at the time of the Punic Wars, 600 b.c., and the first actual excavations are believed to have taken place at this time.. They cover an area of some 12 square miles, and as yet but a small proportion has been worked. In 1927 the output was 2,500 tons in 1935 it was 1,227 tons, the output having been restricted in 1930 the present production is not known. Mercury mining is an unhealthy task, and in the early days it was allotted to slaves later it was the duty of convicts, and the Spanish Government at one time granted exemption from military service to men who had been at Almaden for two years. 

---