ARCHIVED REPORTS_XR0005851 CASE 2

Home Browse Search

1 1. Sample retrieval systems suitable for the valid 4.2 Purging ' collection of volatile organic samples are positive displacement bladder pumps, gear driven submersible In a nonpumping well, there will be little or no pumps,syringe samplers and bailers(Barcelona, 1984, vertical mixing of the water, and stratification will Nielsen, 1985) Field conditions and other constraints occur The well water in the screened section will ' will limit the choice of appropriate systems The mix with the ground water due to normal flow focus of concern must remain to provide a valid patterns,but the well water above the screened section sample for analysis,one which has been subjected to will remain isolated,become stagnant,and may lack ' the least amount of turbulence possible the contaminants representative of the ground water Persons sampling should realize that stagnant water Treatment of the sample with sodium thiosulfate may contain foreign material inadvertently or preservative is required only if there is residual deliberately introduced from the surface,resulting in ' chlorine in the water that could cause free radical an unrepresentative sample To safeguard against chlorination and change the identity of the original collecting nonrepresentative stagnant water, the contaminants It should not be used if there is no following guidelines and techniques should be tchlorine in the water adhered to during sampling Holding time for volatiles analysis is seven days It is 1 As a general rule,all monitor wells should be imperative that the sample be shipped or delivered pumped or bailed prior to sampling Purge daily to the analytical laboratory The bottles must be water should be containerized on site or shipped on their sides to aid in maintaining the airtight handled as specified in the site specific seal during shipment, with adequate packing and protect plan Evacuation of a minimum of cooling to ensure that they arrive intact one volume of water in the well casing, and preferably three to five volumes, is For collection of volatile organic samples, refer to the recommended for a representative sample work plan to ensure that 40 mL glass sample vials In a high-yielding ground water formation Ile with Teflon lined septa are ordered and in sufficient and where there is no stagnant water in the numbers Check sampling supplies, field kit for well above the screened section, evacuation chlorine, preservatives, Parafilm, foam sleeves and prior to sample withdrawal is not as critical coolers Due to the extreme trace levels at which However, in all cases where the monitoring ' volatile organics are detectable, cross contamination data is to be used for enforcement actions, and introduction of contaminants must be avoided evacuation is recommended Trip blanks are incorporated into the shipment ' package to provide a check against cross 2 When purging with a pump(not a bailer), the contamination pump should be set at the screened interval, or if the well is an open-rock well, it should 4.0 INTERFERENCES AND be set at the same depth the sample will be POTENTIAL PROBLEMS collected When sampling a screened well, the sample should also be collected from the 41 General same depth the pump was set at ' The primary goal in performing ground water 3 The well should be sampled as soon as sampling is to obtain a representative sample of the possible after purging ground water body Analysis can be compromised by field personnel in two primary ways (1) taking an 4 Analytical parameters typically dictate unrepresentative sample,or(2)by incorrect handling whether the sample should be collected of the sample There are numerous ways of through the purging device, or through a ' introducing foreign contaminants into a sample, and separate sampling instrument these must be avoided by following strict sampling procedures and utilizing trained field personnel 5 For wells that can be pumped or bailed to dryness with the equipment being used, the ' well should be evacuated and allowed to • 2 1