Common use of Sampling Procedure Clause in Contracts

Sampling Procedure. The first field visit was performed on April 18, 1989 for the purpose of identifying as many of the B-series well▇ ▇▇ possible. Well▇ ▇▇▇t were identified were marked for easy identification during sampling. Well▇ ▇▇▇ing removable caps were sounded. The total depth of the well and the depth to water, when found, were recorded. Well▇ ▇▇▇taining standing water were pumped out and observed to determine whether water levels recovered. This pumping was performed to ensure that water present in the well represented groundwater rather than water that had collected in the PVC probe. In each case where water was pumped from a well, the water level rapidly recovered, indicating that the water level represented the actual groundwater level. The status of the existing well▇ ▇▇▇ summarized in Table 2. Once the sampleable B-series well▇ ▇▇▇e identified, the first phase of soil vapor sampling ensued. The second and third phases of sampling followed the construction of the new vapor well▇. The objective of subsurface landfill gas sampling is to collect samples of soil vapor that are chemically representative of the well air. The soil vapor sample collection device is depicted in Figure 3. The device is designed such that the sample can be collected without passing through the sampling pump. The device utilized teflon tubing which minimizes the potential for interaction with sample constituents or the introduction of contaminants. However, the B-series well▇ ▇▇▇e constructed with sampling lines of flexible plastic tubing (Tygon) that acted as the small inflow line to the collection device. The sampling device is constructed with a 3-way stopcock that permits the purging of the sampling lines prior to sample collection. Prior to the use of the air sampling device, all materials were washed with a mild detergent and rinsed with distilled water and allowed to air dry for at least 24 hours. The tedlar bags used for sample collection were prepared by Sequoia Analytical Laboratory by flushing them with ultra-high pure-grade nitrogen. Five days had passed between the installation of the new vapor well▇ ▇▇▇ the date of their sampling. The target sample volume for each of the samples was five liters or more, collected over a two to four hour period. The pumping rate ranged from 25 to 50 cc/minute. The amount of air moved through the sampling pump is not the same as the sample volume, since the pump serves in providing a pressure drop in the sampling container rather than in directly collecting the air. There are some losses associated with the creation of the pressure differential. Actual sampling periods ranged from 2 hours to over 6 hours. A trip blank was submitted for each of four sampling days. The trip blank consisted of a tedlar bag that was flushed and then filled with nitrogen by the laboratory. Trip blanks were transported with the other sampling bags to the site and returned to the laboratory for analysis. All samples were analyzed within 24 hours of receipt at the laboratory. Figure 3: Components of Direct Air Sampling System Used in Soil Vapor Investigation This diagram depicts a cup-shaped air sampling tool, with a handle and rectangular pump connected to the center of the tool by a tube called a "Vacuum Line Polyethylene Tube." 111 Copies of the sampling data analysis request forms and chain-of-custody records for the samples are contained in Appendix A.