1、Designation:D5785/D5785M20Standard Practice for(Analytical Procedure)for Determining Transmissivity ofConfined Nonleaky Aquifers by Underdamped WellResponse to Instantaneous Change in Head(Slug Test)1This standard is issued under the fixed designation D5785/D5785M;the number immediately following th
2、e 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 covers determina
3、tion of transmissivityfrom the measurement of the damped oscillation about theequilibrium water level of a well-aquifer system to a suddenchange of water level in a well.Underdamped response ofwater level in a well to a sudden change in water level ischaracterized by oscillatory fluctuation about th
4、e static waterlevel with a decrease in the magnitude of fluctuation andrecovery to initial water level.Underdamped response mayoccur in wells tapping highly transmissive confined aquifersand in deep wells having long water columns.1.2 This analytical procedure is used in conjunction with thefield pr
5、ocedure Test Method D4044/D4044M for collection oftest data.1.3 LimitationsSlug tests are considered to provide anestimate of transmissivity of a confined aquifer.This testmethod requires that the storage coefficient be known.As-sumptions of this practice prescribe a fully penetrating well(awell ope
6、n through the full thickness of the aquifer),but the slugtest method is commonly conducted using a partially penetrat-ing well.Such a practice may be acceptable for applicationunder conditions in which the aquifer is stratified and horizon-tal hydraulic conductivity is much greater than vertical hyd
7、rau-lic conductivity.In such a case the test would be considered tobe representative of the average hydraulic conductivity of theportion of the aquifer adjacent to the open interval of the well.The method assumes laminar flow and is applicable for a slugtest in which the initial water-level displace
8、ment is less than0.1 or 0.2 of the length of the static water column.1.4 This practice for analysis presented here is derived byvan der Kamp(1)2based on an approximation of the under-damped response to that of an exponentially damped sinusoid.A more rigorous analysis of the response of wells to a su
9、ddenchange in water level by Kipp(2)indicates that the methodpresented by van der Kamp(1)matches the solution of Kipp(2)when the damping parameter values are less than about 0.2and time greater than that of the first peak of the oscillation(2).1.5 UnitsThe values stated in either SI units or inch-po
10、und units are to be regarded separately as standard.Thevalues in each system may not be exact equivalents;thereforeeach system shall be used independently of the other.Combin-ing values from the two systems may result in non-conformance with the standard.Reporting of test results inunits other than
11、SI shall not be regarded as nonconformancewith this practice.1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.7 This practice offers a set of instructions for performingone or more specific operations.This docume
12、nt cannot replaceeducation or experience and should be used in conjunctionwith professional judgment.Not all aspects of the 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 servi
13、ce must be judged,nor should this document be applied without the considerationof a projects many unique aspects.The word“Standard”inthe title of this document means only that the document hasbeen approved through the ASTM consensus process.1.8 This standard does not purport to address all of thesaf
14、ety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.9 This international standard was developed in accor-dance wi
15、th internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.1This practice is under the jurisdiction of
16、 ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved May 15,2020.Published May 2020.Originallyapproved in 1995.Last previous edition approved in 2015 as D5785 15.DOI:10.1520/D5785_D5785M-20.2The boldface numbers given in parentheses refer to a list of references at theend of the text.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Har