1、Designation: D5786 17Standard 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 ado
2、ption 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 methods for controlling draw-down and measuri
3、ng 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).1.3 The appropriate field and analytical procedures fordetermining hydraulic propertie
4、s 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 applic
5、a-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 applic
6、able 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
7、 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 ContainedFluidsD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and
8、Rock asUsed in Engineering Design and ConstructionD4043 Guide for Selection of Aquifer Test Method inDetermining Hydraulic Properties by Well Techniques3. Terminology3.1 DefinitionsFor common definitions of terms used inthis practice, refer to Terminology D653.4. Summary of Practice4.1 This practice
9、 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
10、Constant drawdown test procedures are used with ap-propriate analytical procedures to determine transmissivity,hydraulic conductivity, and storage coefficient of aquifers.NOTE 1The quality of the result produced by this standard isdependent on the competence of the personnel performing it and thesui
11、tability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itself assurereliable result
12、s. Reliable results depend on many factors: Practice D3740provides a means of evaluating some of those factors.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 appa
13、ratus 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.1This practice is under the jurisdiction of ASTM Committee D18 on
14、 Soil andRock and is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved Jan. 1, 2017. Published January 2017. Originallyapproved in 1995. Last previous edition approved in 2012 as D5786 95 (2012).DOI: 10.1520/D5786-17.2The boldface
15、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
16、onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on s
17、tandardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16.3 Head measurements can be made using one of thefollowing apparatuses:6.3.1 Standpi
18、peA pipe or piece of well casing may beinstalled to extend above the elevation of the discharge. Thisstandpipe will also extend above the elevation of the head inthe control well. This standpipe will allow for direct measure-ment of the water level.6.3.2 Pressure MeasurementA pressure gauge (mechani
19、-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 th
20、at 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 thickness of the aquifer) as effi-ciently as practical to reduce head loss between the aquifer andthe well. Well development should be
21、 as complete as practicalto eliminate additional production of sediments (aquifer par-ticles or drill cuttings) and consequent changes in well effi-ciency during the test.7. Procedure7.1 Pretest Procedures:7.1.1 Select Aquifer Test MethodDevelop a conceptualmodel of the site hydrogeology and select
22、the appropriateaquifer test method in accordance with Guide D4043. Observethe requirements of the selected test method with regard tospecifications for the control well and observation wells.7.1.2 Field ReconnaissanceMake a field reconnaissanceof the site before conducting the test to collect as muc
23、h detailas practical on the depth, continuity, extent, and preliminaryestimates of the hydrologic properties of the aquifers andconfining beds. Note the location of existing wells and water-holding or conveying structures that might interfere with thetest. Turn off nearby wells well before the test,
24、 and disableautomatic pump controls throughout the anticipated test period.Alternately, it may be necessary to pump some nearby wells orallow them to flow throughout the test. If so, the discharge shallbe at a constant rate, and not be started or stopped during thetest and prior to the test for a du
25、ration equal to that of the test.The control well should be equipped with a pipeline orconveyance structure adequate to transmit water away from thetest site, such that the structure does not impede the flow ofwater from the control well.7.1.3 Construction of Control WellScreen the control wellthrou
26、ghout the full extent of the aquifer to be tested.7.1.4 Test of Control WellTest the control well by allowingthe well to flow and then stopping the flow. Based on therecovery response, make a preliminary estimate of the hydrau-lic properties of the aquifer and estimate the initial flow ratefrom the
27、control well expected during the aquifer test.7.1.5 Testing Observation WellsTest observation wells orpiezometers prior to the aquifer test to make sure that they arehydraulically connected to the aquifer. Accomplish this byadding or withdrawing a known volume of water (slug) andmeasure the water-le
28、vel response in the well. The resultantresponse should be rapid enough to make sure that the waterlevel in the observation well or piezometer will reflect thewater level in the aquifer during the test. Alternatively, ifobservation wells are flowing, measure their response in amanner similar to that
29、described for the control well. Rede-velop wells or piezometers with unusually sluggish response.7.1.6 Measure the pressure head in the shut-in control welland observation wells (if any) to determine the trend of waterlevels before the commencement of the test. This period shouldbe equal to the leng
30、th of the flowing portion of the test.7.2 Test Procedure:7.2.1 Based on pretesting results and the conceptual modelof the site (see Guide D4043), select the duration of the test.7.2.2 Shut in the Control WellCompletely stop flow fromthe control well prior to conducting the test for a period as longa
31、s the anticipated duration of the flowing portion of the test.7.2.3 Discharge from Control WellAllow the control wellto flow at a variable rate. The flow rate will vary naturally tomaintain a constant drawdown at the control well.7.2.4 Measure Discharge RateMeasure and record thedischarge rate frequ
32、ently during the early phase of discharge;increase the interval between measurements in a logarithmicmanner as pumping continues.NOTE 2Table 1 presents a suggested frequency of discharge measure-ments.7.2.5 Measure Water LevelMeasure and record the waterlevels in nearby wells at a frequency similar
33、as presented inTable 1.7.3 Post-Testing Procedures:7.3.1 Tabulate water levels, including pre-flowing (shut-in),flowing, and post-flowing levels. For each well or piezometerrecord the date, clock time, time since flowing started orstopped, and the measurement point.7.3.2 Tabulate the rate of dischar
34、ge of the control well, thedate, clock time, time since flowing started or stopped, and themethod of measurement.7.3.3 Prepare a written description of each well, describingthe measuring point, giving its elevation and the method ofobtaining the elevation, and the distance of the measuring pointabov
35、e the mean land surface.7.3.4 Plot the Rate of Discharge Versus TimePrepare aplot of the rate of discharge versus the time since dischargebegan.8. Report: Test Data8.1 Record as a minimum the following general information(data).TABLE 1 Example of Measurement FrequencyFrequency Elapsed Time1 measurem
36、ent every:30 s 3 min1min 3to15min5 min 15 to 60 min10 min 60 to 120 min20 min 2 to 3 h1h 3to15h5 h 15 to 60 hD5786 1728.2 Prepare a report containing field data including a de-scription of the field site, plots of water level and dischargewith time, and preliminary analysis of data:8.2.1 An introduc
37、tion stating the purpose of the test, datesand times water-level measurements commenced, dates andtimes the control well was shut in, dates and times the controlwell began to flow, and the stabilized head in the control wellprior to the test.8.2.2 The as-built description and diagrams of control wel
38、ls,observation wells, and piezometers.8.2.3 A map of the site showing area well locations, thedistances between wells, and locations of all geologic bound-aries or surface-water bodies which might affect the test.8.2.3.1 The locations of wells and boundaries that affect theaquifer tests need to be k
39、nown with sufficient accuracy toprovide a valid analysis. For most analyses, this means thelocations should provide data points within the plotting accu-racy on the semilog or log-log graph paper used in the analysis.Radial distances from the control well to the observation wellsusually need to be k
40、nown with 60.5 %. For prolonged large-scale testing, it may be sufficient to locate wells from maps oraerial photographs. However, for small-scale tests, well loca-tions should be surveyed using land surveying methods. Whentest wells are deep relative to their spacing it may be necessaryto conduct w
41、ell-deviation surveys to determine the true hori-zontal distance between well screens in the aquifer.8.2.4 Include tabulated field data collected during the test.8.2.5 The names and organizations of personnel performingthe tests and calculations.9. Keywords9.1 aquifers; aquifer tests; control wells;
42、 groundwater; hy-draulic conductivity; observation wells; storage coefficient;transmissivityREFERENCES(1) Jacob, C. E., and Lohman, S. W., “Nonsteady Flow to a Well ofConstant Drawdown in an Extensive Aquifer,” American GeophysicalUnion Transactions, Vol 33, No. 4, 1952, pp. 552569.(2) Lohman, S. W.
43、, “Ground-Water Hydraulics,” Professional Paper 708,U.S. Geological Survey, 1972.(3) Hantush, M. S., “Nonsteady Flow to Flowing Wells in LeakyAquifer,” Journal of Geophysical Research, Vol 64, No. 8, 1959, pp.10431052.SUMMARY OF CHANGESCommittee D18 has identified the location of selected changes to
44、 this standard since the last issue(D5786 - 95(2012) that may impact the use of this standard. (January 1, 2017)(1) Removed jargon and superlatives.(2) Updated Terminology section.(3) Edited Section 3 and 8 titles to reflect current D18requirements.(4) Added D3740 to referenced ASTM Standards and ad
45、dedNote 1 to the Significance and Use Section.(5) Added names and organizations performing work to reportSection 8.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly ad
46、vised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, eithe
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