ASTM_D_5786_-_95_2012.pdf

Designation:D578695(Reapproved 2012)Standard Practice for(Field Procedure)for Constant Drawdown Tests in FlowingWells for Determining Hydraulic Properties of AquiferSystems1This standard is issued under the fixed designation D5786;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the methods for controlling draw-down and measuring discharge rates and head to analyze thehydraulic properties of an aquifer or aquifers.1.2 This practice is used in conjunction with analyticalprocedures such as those of Jacob and Lohman(1)/(2),2andHantush(3)/(4).1.3 The appropriate field and analytical procedures fordetermining hydraulic properties of aquifer systems are se-lected as described in Guide D4043.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.5 This practice offers a set of instructions for performingone or more specific operations.This document cannot replaceeducation or experience and should be used in conjunctionwith professional judgment.Not all aspects of this practice maybe applicable in all circumstances.This ASTM standard is notintended to represent or replace the standard of care by whichthe adequacy of a given professional service must be judged,nor should this document be applied without consideration ofa projects many unique aspects.The word“Standard”in thetitle of this document means only that the document has beenapproved through the ASTM consensus process.2.Referenced Documents2.1 ASTM Standards:3D653 Terminology Relating to Soil,Rock,and ContainedFluidsD4043 Guide for Selection of Aquifer Test Method inDetermining Hydraulic Properties by Well TechniquesD4750 Test Method for Determining Subsurface LiquidLevels in a Borehole or Monitoring Well(ObservationWell)(Withdrawn 2010)43.Terminology3.1 DefinitionsFor definitions of terms used in thispractice,see Terminology D653.4.Summary of Practice4.1 This practice describes the field procedures for conduct-ing an aquifer test on a well that is flowing,that is,the head inthe well remains above the top of the well casing.This methodinvolves inducing a constant drawdown and measuring thevarying discharge rate from the control well.5.Significance and Use5.1 Constant drawdown test procedures are used with ap-propriate analytical procedures to determine transmissivity,hydraulic conductivity,and storage coefficient of aquifers.6.Apparatus6.1 Various types of equipment can be used to measure theflow rate of the well.The equipment shall be sized so that itdoes not constrict the flow rate from the well.6.2 An apparatus shall be placed on the control welldischarge line such that the well can be shut in to prevent flowprior to conducting this field procedure and so that theapparatus will not constrict flow from the well when it isallowed to flow.6.3 Head measurements can be made using one of thefollowing apparatuses:6.3.1 StandpipeA pipe or piece of well casing may beinstalled to extend above the elevation of the discharge.This1This practice is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved May 1,2012.Published December 2012.Originallyapproved in 1995.Last previous edition approved in 2006 as D5786 95(2006).DOI:10.1520/D5786-95R12.2The boldface numbers in parentheses refer to a list of references at the end ofthis standard.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 standpipe will also extend above the elevation of the head inthe control well.This standpipe will allow for direct measure-ment of the water level following methods described in TestMethod D4750.6.3.2 Pressure MeasurementA pressure gauge(mechani-cal gage,manometer,or pressure transducer)may be installedbelow the shut-in mechanism in the control well.Determinethe head elevation by adding the pressure reading(expressed inthe height of the water)to the elevation of the sensor of thepressure gage.6.4 Control WellThis practice requires that water flowfrom a single well.This well,known as the control well,shallbe drilled and completed such that it transmits water from theaquifer(usually the entire thi