FLOOD05005 - Laserfiche WebLink

Home Browse Search

CHAPTER 4 VISUAL INSPECTION 21 U WHAT AND WHY SO IMPORTANT Visual inspection performed on a regular basis is the most economical aid a dam owner can use to assure the safety and long life of the structure. Visual inspec- tion is a straightforward procedure that allows any properly trained person to make an accurate assess- ment of a dam's condition. The inspection involves careful examination of the surface on all parts of the structure. The equipment required is not expensive and the inspection usually can be completed in less than one day. The essentials of the inspection will be discussed after a look at useful inspection equipment and inspection findings that must be recorded. 4.2 INSPECTION EQUIPMENT AND ITS USE HARD HAT - A hard hat is recommended for inspecting large outlets or working in construction areas. INSPECTION CHECK LIST - Serves as a reminder to inspect for all important conditions. An example is presented at the end of this chapter. NOTEBOOK AND PENCIL ~ It is very important to write down observations at the time they are made. This reduces mistakes and the need to return to the area to refresh the inspector's memory. TAPE RECORDER - A small portable tape record- ercan also be used effectively to make a record offield observations. CAMERA - Photographs provide a reliable record of observed field conditions. They can be valuable in comparing past and present configurations. An inex- pensive model usually takes pictures good enough for inspection records. HAND LEVEL - This is needed to locate accurately areas of interest and to determine embankment heights and slope. PROBE - A probe can provide information on con- ditions below the surface, such as the depth and soft- ness of a saturated area. Also, by observing moisture brought up on the probe's surface, the inspector can decide whether an area is saturated or simply moist. An effective and inexpensive probe can be made by removing the head from a golf club. POCKET TAPE - Many descriptions are not accu- rate enough when estimated or paced. The pocket tape provides accurate measurements which allow meaningful comparisons to be made. FLASHLlG HT - The interior of an outlet in a small dam can often be inspected adequately without crawl- ing through by using a good flashlight or fluorescent lantern. SHOVEL - A long-handled shovel is useful in clear- ing drain outfalls, removing debris, locating monitor- ing points, and killinll snakes and rodents. ROCK HAMMER - Questionable-looking nprap . or concrete can be checked for soundness with a rock hammer. Care must be taken not to break through thin spots or cause unnecessary damage. BONKER - The condition of support material behind concrete or asphalt faced dams cannot be determined by observing the surface of facing. By firmly tapping the surface of the facing material, con- ditions below can be determined by the sound pro- duced when the material is tapped. Facing material fully supported by fill material produces a uclicku or ubink" sound, while facing material that is over a void or hole in the facing produces a "c1onk" or "bonk" sound. The bonker can be made of I Y.-inch hard wood dowel with a metal tip firmly affixed to the tapping end. A rubber shoe like those on some furni- ture legs is recommended for the other end to allow the bonker to be used as a walking aid on steep, slippery slopes. BINOCULARS - These are useful for inspecting limited access areas especially on concrete dams. GALLON CONTAINER AND TIMER ~ These are used to make accurate measurements of leakage flows. Establishing the time it takes the seepage flow to fill the gallon bucket enables the inspector to calcu- late the number of gallons per minute. Various con- tainer sizes may be required, depending on the flow rates. FIGURE 4.2-1 INSPECTION EQUIPMENT - Notebook, pencil, hand- level, camera, tape recorder and tape, binoculars, pro be, hard hat, pocket tape, flashlight, bonker, shovel" rock hammer, bucket and stopwatch, bugspray, flagging tape and stakes, waterproof boots. STAKES AND FLAGGING TAPE ~ These are used to mark areas requiring future attention and to stake the limits of existing conditions, such as cracks and wet areas, to allow future comparison. WATER TIG HT BOOTS - These are often required when inspecting various areas of the dam site where standing water is present. BUG REPELLENT - Biting bugs can gravely reduce the efficiency and effectiveness of the inspector and sO:lr his disposition. SNAKE BITE KIT -In areas where rattlesnakes or other poisonous snakes might be present, it is recom- mended that a snake bite kit be kept handy.