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|Title:||Evaluation of four well casing materials for monitoring selected trace level organics in ground water|
|Authors:||U.S. Army Toxic and Hazardous Materials Agency.|
Parker, L. V. (Louise V.)
Jenkins, Thomas F.
Black, Patrick B.
|Keywords:||Ground water quality|
Trace level organics
Well casing materials
|Publisher:||Cold Regions Research and Engineering Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||CRREL report ; 89-18.|
Abstract: In this study we examined four well casing materials, polyvinyl chloride (PVC), Teflon, stainless steel 304 (SS 304) and stainless steel 316 (SS 316), to determine their suitability for monitoring selected trace level organic constituents in ground water. Analyte solutions containing pieces of the different well casings were compared to controls that did not contain any well casing material. The aqueous test solution contained approximately 2 mg/L of each of the following organic substances: hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), trinitrobenzene (TNB), cis- and trans-1,2-dichloroethylene (CDCE and TDCE), m-nitrotoluene (MNT), trichloroethylene (TCE), chlorobenzene (CLB), and o-, p-, and m-dichlorobenzene (ODCB, PDCB, and MDCB). Mercuric chloride was added to prevent biodegradation of the analytes. The two sets of isomers for DCE and DCB were selected to examine the effect of structure on sorption. Samples were taken after 0 hour, 1 hour, 8 hours, 24 hours, 72 hours, 7 days (168 hours), and approximately 6 weeks (1000 hours). There was no loss of any analyte in the samples that contained either type of stainless steel casing, although both types of casing rusted. The greatest losses were seen in samples that contained Teflon casings, especially for the chlorinated organics. Losses of PDCB and MDCB were the greatest, 16% and 18%, respectively, after only 8 hours. While losses were also observed for the samples containing PVC casing, the rate of loss was much slower, and usually 24 hours or more elapsed before losses were significant (more than 5%). After the 1000-hour samples were taken, the casings were rinsed and placed in clean vials containing fresh water and left for three days to allow for desorption. From both plastic casings we recovered measurable quantities of all the organics that had been lost from solution. We were able to correlate the loss of hydrophobic organic constituents in the ground water containing the Teflon casings with the substance's octanol-water partition coefficients, although this correlation overestimates losses of hydrophilic organics. Our results indicate that Teflon casings are probably not suitable for monitoring trace level organics. For wells that are purged and sampled within an 8- to 24-hour period, PVC well casings probably are suitable for monitoring trace level organics.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||CRREL Report|
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