1、Designation:D591220Standard Practice for(Analytical Procedure)Determining Hydraulic Conductivityof an Unconfined Aquifer by Overdamped Well Response toInstantaneous Change in Head(Slug)1This standard is issued under the fixed designation D5912;the number immediately following the designation indicat
2、es 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.Scope*1.1 This practice covers the determination of hydraulic
3、conductivity from the measurement of inertial force free(overdamped)response of a well-aquifer system to a suddenchange in water level in a well.Inertial force free response ofthe water level in a well to a sudden change in water level ischaracterized by recovery to initial water level in an approxi
4、-mate exponential manner with negligible inertial effects.1.2 The analytical procedure in this practice is used inconjunction with the field procedure in Test Method D4044/D4044M for collection of test data.1.3 LimitationsSlug tests are considered to provide anestimate of hydraulic conductivity.The
5、determination of stor-age coefficient is not practicable with this practice.Because thevolume of aquifer material tested is small,the values obtainedare representative of materials very near the open portion of thecontrol well.NOTE1Slug tests are usually considered to provide estimates of thelower l
6、imit of the actual hydraulic conductivity of an aquifer because thetest results are so heavily influenced by well efficiency and borehole skineffects near the open portion of the well.The portion of the aquifer that istested by the slug test is limited to an area near the open portion of the wellwhe
7、re the aquifer materials may have been altered during well installation,and therefore may significantly impact the test results.In some cases,thedata may be misinterpreted and result in a higher estimate of hydraulicconductivity.This is due to the reliance on early time data that is reflectiveof the
8、 hydraulic conductivity of the filter pack surrounding the well.Thiseffect was discussed by Bouwer(1).2In addition,because of the relianceon early time data,in aquifers with medium to high hydraulicconductivity,the early time portion of the curve that is useful for this dataanalyses is too short(for
9、 example,HlnRe/rw!5F1.1lnH/rw!1A1BlnD 2 H!/rw#L/RwG21(2)if D=HlnRe/rw5F1.1lnH/rw!1CL/rwG21(3)NOTE2Other analytical solutions are given by Hvorslev and Cooperet al;(2,3,4)however,they may differ in their assumptions andapplicability.NOTE3Bouwer(1)provided discussion of various applications andobserva
10、tions of the procedure described in this practice.NOTE4Practice D4104/D4104M describes the analytical solutionfollowing Cooper et al(3).NOTE5The use of the symbol K for the term hydraulic conductivityis the predominant usage in groundwater literature by hydrogeologists,whereas,the symbol k is common
11、ly used for this term in soil and rockmechanics and soil science.4.3 More recent work(Zlotnik et al.2010(5)have revealedthat the shape factors used for calculation of hydraulic con-ductivity(K)in the Bouwer and Rice model may result in theunder estimation of K by as much as 25%to 40%dependingon the
12、well construction and aquifer characteristics.Pleaserefer to the work of Zlotnik et al.(2010)(5)for a discussion ofthe development of general steady state shape factors for thecondition of an overdamped,partially penetrating well.4.4 Numerous commercial computer software programs areavailable to eva
13、luate slug test data.Only those programs thatprovide analysis of the data based on graphical curve matching,rather than simply least-squares analysis,and allow for thegeneration of data plots should be used.5.Significance and Use5.1 Assumptions of Solution:5.1.1 Drawdown(or mounding)of the water tab
14、le aroundthe well is negligible.5.1.2 Flow above the water table can be ignored.5.1.3 Head losses as the water enters or leaves the well arenegligible.5.1.4 The aquifer is homogeneous and isotropic.NOTE6Slug and pumping tests implicitly assume a porous medium.3For referenced ASTM standards,visit the
15、 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.D5912 202Fractured roc
16、k and carbonate settings may not provide meaningful dataand information.5.2 Implications of Assumptions:5.2.1 The mathematical equations applied ignore inertialeffects and assume that the water level returns to the static levelin an approximate exponential manner.5.2.2 The geometric configuration of the well and aquiferare shown in Fig.1,that is after Fig.1 of Bouwer and Rice(1).5.2.3 For filter-packed wells,Eq 1 applies to cases in whichthe filter pack remains saturated.If some of the filter pa
