1、Designation: D5521/D5521M 13Standard Guide forDevelopment of Groundwater Monitoring Wells in GranularAquifers1This standard is issued under the fixed designation D5521/D5521M; the number immediately following the designation indicates theyear of original adoption or, in the case of revision, the yea
2、r 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 guide covers the development of screened wellsinstalled for the purpose of obtaining representative ground-
3、water information and water quality samples from granularaquifers, though the methods described herein could also beapplied to wells used for other purposes. Other well-development methods that are used exclusively in open-borehole bedrock wells are not described in this guide.1.2 The applications a
4、nd limitations of the methods de-scribed in this guide are based on the assumption that theprimary objective of the monitoring wells to which themethods are applied is to obtain representative water qualitysamples from aquifers. Screened monitoring wells developedusing the methods described in this
5、guide should yield rela-tively sediment-free samples from granular aquifer materials,ranging from gravels to silty sands. While many monitoringwells are considered “small-diameter” wells (that is, less than10 cm 4 in. inside diameter), some of the techniquesdescribed in this guide will be more easil
6、y applied to large-diameter wells (that is, 10 cm 4 in. or greater insidediameter).1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of
7、 the other. Combiningvalues from the two systems may result in non-conformancewith the standard.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 p
8、ractices and determine the applica-bility of regulatory limitations prior to use.1.5 This guide offers an organized collection of informationor a series of options and does not recommend a specificcourse of action. This document cannot replace education orexperience and should be used in conjunction
9、 with professionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged, nor should thisdocument be applied without considerat
10、ion of a projects manyunique aspects. The word “Standard” in the title of thisdocument means only that the document has been approvedthrough the ASTM consensus process.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD3740 Practice for Minimum Re
11、quirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD5088 Practice for Decontamination of Field EquipmentUsed at Waste SitesD5092 Practice for Design and Installation of GroundwaterMonitoring Wells3. Terminology3.1 Definitions:3.1
12、.1 For definitions of common terminology terms usedwithin this guide, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 air entrapmenttrapping of air or other gas in porespaces of the formation or filter pack during development withcompressed air.3.2.2 air lift pumpa
13、 device consisting of two pipes, withone (the air line) inside the other (the eductor pipe), used towithdraw water from a well. The lower ends of the pipes aresubmerged, and compressed air is delivered through the innerpipe to form a mixture of air and water. This mixture rises inthe outer pipe to t
14、he surface because the specific gravity of thismixture is less than that of the water column.1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved Aug. 1
15、, 2013. Published September 2013. Originallyapproved in 1994. Last previous edition approved in 2005 as D5521 05. DOI:10.1520/D5521_D5521M-13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vol
16、ume information, refer to the standards Document Summary page 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 States13.2.3 air linea small vertical air pipe
17、used in air-liftpumping. It usually extends from the ground surface to near thesubmerged lower end of the eductor pipe. The length of the airline below the static water level is used in calculating the airpressure required to start air-lift pumping.3.2.4 annular sealmaterial used to provide a seal b
18、etweenthe borehole and the casing of a well. The annular seal shouldhave a hydraulic conductivity less than that of the surroundinggeologic materials and be resistant to chemical or physicaldeterioration.3.2.5 backwashingthe reversal of water flow caused bythe addition of water to a well that is des
19、igned to loosen bridgesand facilitate the removal of fine-grained materials from theformation surrounding the borehole.3.2.6 bailing (development)a development technique us-ing a bailer which is raised and lowered in the well to create astrong inward and outward movement of water from theformation t
20、o break sand bridges and to remove fine materialsfrom the well.3.2.7 cable tool drillinga drilling technique in which adrill bit attached to the bottom of a weighted drill stem is raisedand dropped to crush and grind formation materials. Inunconsolidated formations, casing is usually driven as drill
21、ingproceeds to prevent collapse of noncohesive materials into theborehole.3.2.8 eductor pipethe vertical discharge pipe used inair-lift pumping, submerged at least one third but usually twothirds of its length below the pumping water level in the well.3.2.9 filter-packed wella well in which the natu
22、ral forma-tion materials adjacent to the well screen has been replaced bya filter pack material.3.2.10 formation damagereduction of formation hydraulicconductivity at the borehole wall caused by the drillingprocess. May consist of compaction, clay smearing, cloggingof pores with drilling mud filtrat
23、e, or other drilling-relateddamage.3.2.11 hydraulic jettinga well-development method thatemploys a jetting tool with nozzles and a high-pressure pumpto force water outwardly through the well screen, the filterpack, and sometimes into the adjacent geologic unit, for thepurpose of dislodging fine sedi
24、ment and correcting formationdamage done during drilling.3.2.12 indicator parameterschemical parameters, includ-ing pH, specific conductance, temperature and dissolved oxy-gen content, which are used to determine when formationwater is entering a monitoring well.3.2.13 jettingsee hydraulic jetting.3
25、.2.14 naturally developed wella well in which the for-mation materials collapse around the well screen, and fineformation materials are removed using standard developmenttechniques.3.2.15 overpumpinga well-development technique that in-volves pumping the well at a rate that exceeds the designcapacit
26、y of the well.3.2.16 rawhidingstarting and stopping a pump intermit-tently to produce rapid changes in the pressure head in the well.3.2.17 sandlockingrefers to the accumulation of sand andother sediment on development tools while they are working inthe well screen, resulting in the tools becoming l
27、odged in thescreen. Also refers to the accumulation of sand and othersediment in the impeller section of a submersible pump,resulting in the impellers binding.3.2.18 sloughingcaving of formation materials into anunstabilized open borehole.3.2.19 spuddingthe operation, in cable-tool drilling, ofdrill
28、ing a collar hole and advancing a casing through overbur-den. Also a general term in rotary or diamond core drillingapplied to drilling through overburden.3.2.20 sumpa blank extension of easing beneath the wellscreen that provides a space for sediment brought into the wellduring development to accum
29、ulate.3.2.21 surge blocka plunger-like tool consisting of disksof flexible material (for example, neoprene) sandwiched be-tween rigid (for example, metal) disks that may be solid orvalved, and that is used in well development. See surging.3.2.22 surginga well-development technique in which asurge bl
30、ock is alternately raised and lowered within the wellcasing or screen, or both, to create a strong inward and outwardmovement of water through the well screen.3.2.23 tool stringthe drill pipe or drill rod and all attacheddrilling or development tools used in the borehole or well.3.2.24 turbidityclou
31、diness in water due to suspended andcolloidal material.3.2.25 well developmentthe act of repairing damage to theborehole caused by the drilling process and removing fine-grained materials or drilling fluids, or both, from formationmaterials so that natural hydraulic conditions are restored andwell y
32、ields are enhanced.4. Significance and Use4.1 A properly designed, installed, and developed ground-water monitoring well, constructed in accordance with PracticeD5092 should provide the following: representative samples ofgroundwater that can be analyzed to determine physicalproperties and water-qua
33、lity parameters of the sample orpotentiometric levels that are representative of the total hy-draulic head of that portion of the aquifer screened by the well,or both. Such a well may also be utilized for conducting aquifertests used for the purpose of determining the hydraulic prop-erties of the ge
34、ologic materials in which the well has beencompleted.4.2 Well development is an important component of moni-toring well completion. Monitoring wells installed in aquifersshould be sufficiently developed to ensure that they serve theirintended objectives. Well development methods vary with thephysica
35、l characteristics of the geologic formation in which themonitoring well is screened, the construction details of thewell, the drilling method used during the construction of theborehole in which the well is installed, and the quality of thewater. The development method for each individual monitoring
36、D5521/D5521M 132well should be selected from among the several methodsdescribed in this guide and should be employed by the wellconstruction contractor or the person responsible for monitor-ing well completion.4.3 The importance of well development in monitoringwells cannot be overestimated; all too
37、 often development is notperformed or is carried out inadequately. Proper and carefulwell development will improve the ability of most monitoringwells to provide representative, unbiased chemical and hydrau-lic data. The additional time and money spent performing thisimportant step in monitoring wel
38、l completion will minimizethe potential for damaging pumping equipment and in-situsensors, and increase the probability that groundwater samplesare representative of water contained in the monitored forma-tion. Practice D3740 provides evaluation factors for the activi-ties in this guide.NOTE 1The qu
39、ality of the result produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection
40、/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.5. Purposes of Monitoring Well Development5.1 Monitoring wells are deve
41、loped primarily for the fol-lowing reasons:5.1.1 To rectify damage done during drilling to the boreholewall and the adjacent formation (that is, clogging, smearing, orcompaction of formation materials) that may result in alocalized reduction in hydraulic conductivity of the formationnear the borehol
42、e (see Fig. 1);5.1.2 To remove fine-grained materials from the formationand filter pack (where applicable) that may result in theacquisition of turbid, sediment-laden samples;5.1.3 To stabilize formation and artificial filter pack mate-rials (where applicable) adjacent to the well screen (see Fig.23
43、);5.1.4 To retrieve lost drilling fluid (if drilling fluid was usedin the borehole installation process) that may alter the qualityof water in the vicinity of the well and interfere with waterquality analysis (see Fig. 33); and5.1.5 To maximize well efficiency and hydraulic communi-cation between th
44、e well and the adjacent formation to providefor the acquisition of representative groundwater samples andformation hydraulic test data.6. Conducting a Monitoring Well-Development Program6.1 Well Development ProcessThe well development pro-cess consists of three phases: predevelopment, preliminarydev
45、elopment, and final development.6.1.1 Predevelopment refers to techniques used to mitigateformation damage during well construction. This is particularlyimportant when using direct or reverse rotary drilling systemsthat depend on drilling fluid to carry cuttings to the surface andsupport an open bor
46、ehole. Control of drilling fluid properties,during the drilling operation and immediately prior to theinstallation of screen, casing, and filter pack, is very important.6.1.2 Preliminary development takes place after the screen,casing, and filter pack have been installed. Methods used toaccomplish t
47、his task include surging, bailing, hydraulic jetting,and air lifting. The primary purpose of this operation is to applysufficient energy in the well to facilitate rectification offormation damage due to drilling; removal of fine-grainedmaterials from the screen, filter pack, and formation; stabili-z
48、ation and consolidation of the filter pack; retrieval of drillingfluid (if used); and creation of an effective hydraulic interfacebetween the filter pack and the formation.6.1.3 During this phase of well development, the preferredtechnique is to gradually apply the selected method, increasingintensi
49、ty as long as the well responds to treatment. Responsegenerally is indicated by increased yields of water and sedi-ment. Intensive development of a well that appears to beplugged should not be attempted because damage and destruc-tion of the well may result.6.1.4 Final development refers to procedures performedwith a pump, such as pumping and surging, and backwashing.These techniques are used as the final step in achieving theobjectives of well development. If preliminary developmentmethods have been effective, the time required for finaldevelopment s
