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COLORADO LEGACY LAND <br /> - ATTAC UMMARY TABLE OF GROUNDWATER WELL PURGING FROM VARI TURE$OUR <br /> Oxidation- No. Minimum <br /> pH Specific Dissolved Reduction Temperature Turbidity Consecutive Frequency Purge Volume Maximum Purge Alternate Criteria Comments Screen Length Reference <br /> Conductivity Oxygen Potential Readings or time Volume or time Applicability <br /> ORP or Eh <br /> volumes must he Indicator Parameters <br /> removed Stabilization. <br /> regardless of <br /> indicator "This document cannot replace <br /> education or experience and <br /> parameter <br /> levels should be used in conjunction <br /> with professional judgment". <br /> Purge until "Parameters should be selected <br /> parameters are based on knowledge of water <br /> stable. chemistry and analytes of interest, <br /> or regulatory requirements,or <br /> both." <br /> "The acceptable variation of <br /> values to define stabilization and <br /> the minimum number of <br /> consecutive stable readings.." <br /> "..should be defined in the <br /> sampling and analysis plan." <br /> USEPA Science and Ecosystem <br /> Support Division uses multiple <br /> "Frequently volume purging for"typical"wells. <br /> enough to No set criteria for establishing the <br /> Should Not Be Should Not Be Stable(not provide a number of measurements needed <br /> ±0.1 ±5% ±0.2 mg/L Used Used defined)or 3 sufficient number 3 well volumes 5 well volumes None to document parameter stability. Not Specified USEPA(2013) <br /> <10 NTU of measurements <br /> to evaluate If parameters have not stabilized <br /> stability" within 5 well volumes,it is at the <br /> discretion of the project leader to <br /> sample or continue purging. <br /> ±10%when> ±10%when>5 <br /> ±0 ± 0 0.5 mg/L or + o >_5 minute Specific to low-flow sampling..1 /o 3 three values< 10 mV 3/o NTU or three 3 intervals Not Specified 2 hours None p g• s 10 ft. USEPA(2017) <br /> 0.5 m L values<5 NTU <br /> Each'h well Actual number of well volumes to <br /> +10%when volume after be removed is based on <br /> ±0.1 ±3% ±0.3 mg/L ±10 mV ----------------- ->10 NTU 3 removal of 1 to 3 well volumes 6 well volumes None stabilization of indicator :510 ft. USEPA(2018) <br /> 1.5 well volumes. parameters. <br /> References: <br /> ASTM.2012.Standard Guide for Purging Methods for Wells Used for Groundwater Quality Investigations.Designation:D6452-99(Reapproved 2012).ASTM International,West Conshohocken,PA. <br /> Barcelona,M.J.and J.A.Helfrich.1986.Well construction and purging effects on ground-water samples.Environmental Science and Technology.20:1179-1184. <br /> Barcelona,M.J.,H.A.Wehrmann,and M.D.Varljen.1994.Reproducible well purging procedures and VOC stabilization criteria for groundwater sampling.Ground Water,32:12-22. <br /> Karklins,S.1996.Groundwater Sampling Desk Reference.Wisconsin Department of Natural Resources.September. <br /> U.S.Environmental Protection Agency(USEPA).1985.Practical Guide for Ground-Water Sampling.EPA/600/2-85/104.USEPA,Ada,OK. <br /> U.S.Environmental Protection Agency(USEPA).1992.RCRA Ground-Water Monitoring: Draft Technical Guidance.Office of Solid Waste.USEPA,Washington,DC.November. <br /> U.S.Environmental Protection Agency(USEPA).1996.Low-Flow(Minimal Drawdown)Ground-Water Sampling Procedures.EPA/540/S-95/504.April. <br /> U.S.Environmental Protection Agency(USEPA).2002.Ground-Water Sampling Guidelines for Superfund and RCRA Project Managers.EPA 542-S-02-001.May. <br /> United States Geological Survey(USGS).2005.National Field Manual for the Collection of Water Quality Data.Techniques of Water-Resources Investigations,Book 9. <br /> United States Environmental Protection Agency(USEPA).2013.Groundwater Sampling.SESDPROC-301-R3.USEPA,Athens,GA. <br /> United States Environmental Protection Agency(USEPA).2017.Low Stress(low flow)Purging and Sampling Procedure for the Collection of Groundwater Samples.EQASOP-GW4.USEPA Region 1,North Chelmsford,MA. <br /> United States Environmental Protection Agency(USEPA).2018.Standard Operating Procedure for the Standard/Well-Volume Method for Collecting a Ground-Water Sample from Monitoring Wells for Site Characterization.https:///www.epa.gov/sites/.production/files/2015- <br /> 06/documents/finalgwsamp sop.pdf.Accessed 4-18-18. <br /> PAGE 24 OF 24 <br />