ARCHIVED REPORTS_1988_2 - Laserfiche WebLink

Home Browse Search

When the sampling period is to be concluded, the timer first closes the solenoid valve and then turns off the pump. At this time the sample containers or cartridges are sealed and removed for laboratory analysis. New containers or cartridges may be installed if additional sampling is desired such as would be the case with the 10 -day sampling programs mandated for hazardous waste disposal facilities. In response to the need for sampling while walking a grid across the surface of a landfill or patrolling the perimeter of an impoundment, a more portable version of the sampler is shown in Figure 3. Again, All components are stainless steel and Teflon. This sampling system has been designed to meet the sampling requirements of the Calderon landfill monitoring bill (AB 3525) for collecting ambient air samples. A Teflon and glass snorkle can be attached to enable the sampling technician to conveniently draw air from just above the surface of the landfill. If stationary use is planned, the sampling system can be controlled by a progaable timer that allows the system to be set up the day before sampling is to take place. A Teflon -faced stainless steel diaphragm pump capable of providing six liters per minute at no load is used to supply the system from a six foot intake line. The outlet of the pump is connected to a stainless steel four-way fitting configured with a 0-60 psig pressure gauge, a 10-15 prig excess flow vent and a stainless steel line connected to the "Back Pressure flow controller". The flow controller can be adjusted to fill the can at a rate which is approprote for the intendedl sampling period (is. 25 minutes). The flow controller maintains a constant downstream flow rate so that the sample cons can be filled at the some rate over the course of the entire sampling period. The solenoid valves which are part of both types of integrated samplers are the stainless steel magnelatch type and therefore do not require power to hold them open once they have been opened. This prevents outgassing such as is sometimes observed in other types of solenoid valves. After passing through the solenoid valve, the sample is directed to the canister. The sampling line is preflushed with site air prior to being connected to the system thereby removing any contamination which might- have been acquired during shipment and storage. If timed operation is planned, the sampler can then be turned on and off by means of an automatic timer. Thus the sampling technician needs only to place the sampler and collect the canister afterwards. ADVANTAGES AND DISADVANTAGES OF THE METHODS Bag samples involve less contact with reactive surfaces than do cartridges. If properly possivated, the same is true for the steel containers. Therefore there is less chance of irreversible absorptive losses with these two container types. Bogs are more fragile, however, and have shorter holding times than do cartridges. The steel container