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Groundwater Assessment Plan Comments (cont'd) Paqe # Comment 38 A figure depicting the soil gas sampling probe and the related components described on this page should have been provided. Moreover, since Tracer is doing the actual sampling, they have their awn internal workplan that describes their sampling protocol. Tracer's sampling protocol should have been included in this workplan. 38 The first line of this page refers to field personnel ensuring that all soil gas sampling equipment blanks are negative prior to sampling. What is the procedure if an organic constituent is detected in a blank? 43 The last paragraph indicates that one of 6" samples fran each Shelby tube sample will be placed in a sealed ziplock bag, and the headspace analyzed 5-10 minutes later fon total volatiles. In order to better determine the total volatile content of the sample, the soil cone should be broken-up while in the container. Moreover, a constant exposure period (say 10 minutes) should be maintained to ensure relative consistency in the results. Presumably, the sample bags would need to be opened to allow the OVA probe inside (i.e. , the bags are not equiped with a specific port for the OVA probe). A device with a finite OVA access point would be preferable. 44 The first paragraph indicates that 25 ppm above background will be used as the cut-off point for performing laboratory VOC analyses on the soil specimens. The criteria for the selection of Lhis value should be explained, and a reference provided. 46 Paraaraph 3 states that the middle 6" brass tube will be used for chem cal analyses, if passible. Please explain "if possible". 47 Paragraph 4 states that the on-site geologist will determine which three soil samples are to be analyzed in the event that all of the OVA readings in a cone run are belay the 25 ppm above background threshold. It should be stated that the selection of these three will be based on the relative magnitude of OVA readings and soil discoloration, odor, etc. 50 The second sentence discusses the removal of 1.5' of surface soil prior to sampling. For reasons given previously, this uppermost soil layer should be sampled and analyzed. 51 Paragraph 2 discusses the collection of rinsate blank samples. It is unclear, however, whether the sample is being taken fran a specific rinsing event, or fran an aggregate of the rinsate samples for the entire sampling day. Sampling fran the latter would be inappropriate, given that the aggregate sample has been exposed fon several hours and is about to be analyzed for volatiles. As such, an initial and final rinsate blank sample (not from an aggregate sample) should be collected.