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<br />(7) Meters or kits for testing pH. The degree of acidity or alkalinity <br />of soil and water is measured in terms of pH. Testing to determine <br />pH is performed when evaluating durability problems. Meters or test <br />kits may be needed for field testing the pH of soil and water. Empty <br />containers may be needed for sampling soil and water when a <br />laboratory analysis of pH is to be performed. <br /> <br />(8) Resistivity meters. These devices may be needed to measure the <br />electrical resistivity of soil at locations where corrosion problems <br />are found. Electrical resistivity provides an indication of the <br />relative quantity of soluble salts in the soil or backfill materials. <br /> <br />Section 2. SAFETY <br /> <br />2-2.0. General. <br /> <br />The safety of the inspector is extremely important. It is therefore essential <br />that inspectors be aware of and practice safe work procedures. Safety <br />considerations related to culvert inspection are discussed in this section. <br /> <br />2-2.1. Confined Spaces. <br /> <br />a. Hazards. Culverts with inadequate ventilation, such as those with one <br />end blocked by debris, or long runs of culvert pipe in urban drainage systems, <br />may develop a lack of oxygen or hazardous concentrations of toxic gases. <br />Oxygen depletion may result from the slow oxidation of organic matter. Toxic <br />gases, often heavier than air, may seep into and collect in poorly ventilated <br />culverts. When there is any doubt about the quality of air or adequacy of <br />ventilation, safety procedures should be followed. <br /> <br />b. Safety Procedures. <br /> <br />(1) Where air quality is questionable, tests for oxygen content and the <br />presence of hazardous gases should be conducted prior to entry. <br />Hazardous gases may include toxic gases such as hydrogen sulphide and <br />carbon monoxide, and combustible gases such as methane. A variety of <br />devices are available for measuring oxygen levels and detecting <br />hazardous gases. Testing devices for field use range from clip on <br />badges which change color in the presence of a particular gas to <br />portable or hand-held instruments which measure the levels of various <br />gases. Audible alarms are provided with some models. The devices <br />and test procedures used should meet applicable State or Federal <br />Standards such as Occupational Safety and Health Association (OSHA) <br />standards. <br /> <br />(2) When oxygen levels are found to be below established minimum levels, <br />or noxious gases exceed recommended levels, persons should not be <br />allowed to enter the space until proper oxygen and gas contents are <br />established by mechanical ventilation. <br /> <br />12 <br />