Field Methods for the Full Scale Tests Sample Clauses

Field Methods for the Full Scale Tests. Figure 4.1 illustrates a typical configuration for the full-scale flood tests that were completed as part of the current study. A pressure transducer was used to measure the water level in the pond as a function of time. During the filling stage of the test, which typically lasted several hours, water was discharged into the pond and the depth of water increased. The draining stage of the test started when the discharge was terminated. The water level in the pond decreased with time during this draining stage as the water infiltrated through the bottom and sides of the pond. The draining stage lasted from 12 hours to several days, depending upon the rate of infiltration. The pressure transducer, model 15 PSI PS9800 from Instrumentation Northwest, Inc., has an accuracy of 0.1 percent. For a water level in a pond of 24 inches (61 cm), the degree of accuracy is ± 0.18 inches (0.45 cm). The transducer, supported by a steel post that is driven into the pond bottom, measures the height of water above the bottom of the transducer. The transducer is connected to an automatic data acquisition system that collects measurements at pre-determined time intervals. For this study the time interval was 10 minutes. The water used to fill the ponds was obtained by connecting a 2.5-inch (6.35-cm) diameter hose to a fire hydrant. The flow rate, which was controlled with a valve at the hydrant, was measured with a water meter provided by the local water utilities. These meters measure to the nearest 10 cubic feet (0.3 cubic meter). Surveying measurements were taken to calculate the pond geometry. A level and tripod were used to measure elevation along the pond bottom and side slopes. Elevation measurements were collected along transects with a horizontal spacing between measurements of approximately 4 to 6 feet (1.2 to 1.8 m), depending on the site. The length and width of the pond bottom were measured with a steel tape measurer. The side slopes (change in elevation divided by change in horizontal distance) ranged from 0.3 to 0.7 for the three sites.