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Page 3-3 . Section 3 . 2 <br /> 13 . Two samples of cuttings from Well No. 1 and one sample from <br /> Well No. 2 are proposed. The first cuttings to be collected <br /> from a depth of 35 feet in each well, or five feet below the <br /> grout seal. Since the current water level in the vicinity <br /> of these wells is in the range of 16 to 21 feet bgs it would <br /> be prudent to sample within one to two feet of the base of <br /> the grout seal. If the casing has deteriorated at a depth <br /> which would allow groundwater from any of the contaminated <br /> horizons in the upper "120 feet to enter the casing, the <br /> groundwater level within the casing may be found to be much <br /> higher than the 1942 level of 60 feet bgs. Also, the <br /> magnitude of historical fluctuations in groundwater level <br /> since 1942 and the possible effects on groundwater flow <br /> directions must be considered. <br /> Because the contaminants of concern are known as "sinkers" <br /> and will typically sink to the bottom of the water column, <br /> it would seem reasonable to retrieve further cuttings <br /> samples from the lower portions of the wells, perhaps <br /> adjacent to or below the original perforations to determine <br /> whether there has been downward migration of contaminants. <br /> • State in the text whether the DLA will retrieve further <br /> cuttings samples, as recommended. <br /> Pages 3-3 and 3-4 . Section 3 . 3 <br /> 14 . There is no mention of any purging procedures prior to <br /> retrieval of groundwater samples. No matter what the <br /> condition of the casing, sampling the groundwater without <br /> purging, after drilling out the sand pack and quite possibly <br /> introducing "potable water and drilling fluids" will not <br /> produce data representative of the quality of groundwater in <br /> Wells No. 1 and 2 . It is suggested that a controlled <br /> purging of the wells be performed, while monitoring <br /> groundwater parameters such as pH, Eh, specific conductance <br /> and temperature to estimate when the aquifer water has <br /> entered the well. If integrity of the casing is a concern, <br /> then perhaps the video logging of the wells should be <br /> performed prior to and after presampling purging. After <br /> purging the turbidity should be lower in the well, offering <br /> a better resolution of the video logging and also would <br /> provide information on whether the purging has caused any <br /> further damage to the casing, perhaps opening new <br /> perforations which should be considered in decisions on <br /> sampling depths of the groundwater. <br /> • State in the text whether DLA will use controlled <br /> purging. <br /> 5 of 12 <br />