ASTM_D_5092_-_D_5092M_-_16.pdf

Designation:D5092/D5092M16Standard Practice forDesign and Installation of Groundwater Monitoring Wells1This standard is issued under the fixed designation D5092/D5092M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This practice describes a methodology for designing andinstalling conventional(screened and filter-packed)groundwa-ter monitoring wells suitable for formations ranging fromunconsolidated aquifers(that is,sands and gravels)to granularmaterials having grain-size distributions with up to 50%passing a#200 sieve and as much as 20%clay-sized material(that is,silty fine sands with some clay).Formations finer thanthis(that is,silts,clays,silty clays,clayey silts)can bemonitored but the well may not yield sufficient water requiredfor sampling,and fine filter pack and screen requirements aredifficult and costly to install.Use of coarser filter/screens infine formations will result in wells with unstable filter packsand associated elevated sample turbidity that may adverselyaffect sample accuracy and data quality objectives.Thispractice is not applicable in fractured or karst rock conditions,but may be applicable for other porous rock formations.1.2 The recommended monitoring well design and installa-tion procedures presented in this practice are based on theassumption that the objectives of the program are to obtainrepresentative groundwater samples and other representativegroundwater data from a targeted zone of interest in thesubsurface defined by site characterization.1.3 This practice when used on coarse grained sand andgravel aquifers,in combination with proper well development(D5521),proper groundwater sampling procedures(D4448),and proper well maintenance and rehabilitation(D5978),willpermit acquisition of groundwater samples free of artifactualturbidity,eliminate siltation of wells between sampling events,and permit acquisition of accurate groundwater levels andhydraulic conductivity test data from the zone screened by thewell.For wells installed in fine-grained formation materials,itis generally necessary to use much finer pre-packed wellscreens(6.3.3.2)and/or employ sampling methods that mini-mize screen intake flow velocity,and disturbance of the wellcolumn including suspension of settled solids in the well.Using low-flow purging and sampling techniques(D6771)orpassive sampling devices(D7929)are two means to minimizethe potential sample bias associated with turbidity.1.4 This practice applies primarily to well design andinstallation methods used in drilled boreholes.Other standards,including Guide D6724 and Practice D6725,cover installationof monitoring wells using direct-push methods.1.5 UnitsThe values stated in either inch-pound units orSI units presented in brackets are to be regarded separately asstandard.The values stated in each system may not be exactequivalents;therefore,each system shall be used independentlyof the other.Combining values from the two systems mayresult in non-conformance with the standard.Equivalent valuesgiven in parentheses are shown for mix designs and sievessizes.1.5.1 Sieve Designations(Specification E11)are identifiedusing the“alternate”system,for example,#40,#200 sieve etc.with nominal opening size in inches and particle sizes in mm.See Specification E11 for standard metric sieve sizes.1.5.2 Well screen slots are expressed in inches and themetric equivalent is given in the terminology section and whennecessary in the standard(see 3.3.6).1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026,unless superseded by this standard.1.7 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.1.8 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.Nat 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.1This 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