1、Designation: D5980 16Standard Guide forSelection and Documentation of Existing Wells for Use inEnvironmental Site Characterization and Monitoring1This standard is issued under the fixed designation D5980; the number immediately following the designation indicates the year oforiginal adoption or, in
2、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 guide covers the use of existing wells for environ-mental site characterizatio
3、n and monitoring. It covers thefollowing major topics: criteria for determining the suitabilityof existing wells for hydrogeologic characterization andgroundwater quality monitoring, types of data needed todocument the suitability of an existing well, and the relativeadvantages and disadvantages of
4、existing large- and small-capacity wells.1.2 This guide should be used in conjunction with GuideD5730, that provides a general approach for environmental siteinvestigations.1.3 This guide does not specifically address design andconstruction of new monitoring or supply wells. Refer toPractices D5092
5、and D5787.1.4 This guide does not specifically address groundwatersampling procedures. Refer to Guide D5903.1.5 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety conce
6、rns, 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.1.7 This guide offers an organized collection of informationor a series of options
7、and does not recommend a specificcourse of action. This guide cannot replace education orexperience and should be used in conjunction with professionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This guide is not intended to represent orreplace the standard of care
8、 by which the adequacy of a givenprofessional service must be judged, nor should this guide beapplied without consideration of a projects many uniqueaspects. The word “Standard” in the title of this documentmeans only that the document has been approved through theASTM consensus process.2. Reference
9、d Documents2.1 Pertinent guides addressing specific information neces-sary to utilize existing wells for hydrologic and water-qualitydata for environmental site characterization. A comprehensivelist of guides, standards, methods, practices, and terminology iscontained in Guide D5730. Other guidance
10、documents cover-ing procedures for environmental site investigations withspecific objectives or in particular geographic settings may beavailable from federal, state, and other agencies or organiza-tions. The appropriate agency or organization should becontacted to determine the availability and mos
11、t current editionof such documents.2.2 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD5092 Practice for Design and Installation of GroundwaterMonitoring WellsD5254 Practice for Minimum Set of Data Elements toIdentify a Ground-Water SiteD5408 Guide for Set of Data Elemen
12、ts to Describe aGroundwater Site; Part OneAdditional IdentificationDescriptorsD5409 Guide for Set of Data Elements to Describe aGround-Water Site; Part TwoPhysical DescriptorsD5410 Guide for Set of Data Elements to Describe aGroundwater Site;Part ThreeUsage Descriptors (With-drawn 2016)3D5521 Guide
13、for Development of Groundwater MonitoringWells in Granular AquifersD5730 Guide for Site Characterization for EnvironmentalPurposes With Emphasis on Soil, Rock, the Vadose Zoneand Groundwater (Withdrawn 2013)31This guide is under the jurisdiction of ASTM Committee D18 on Soil andRockand is the direct
14、 responsibility of Subcommittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved Oct. 1, 2016. Published October 2016. Originallyapproved in 1996. Last previous edition approved in 2010 as D598096(2010)1.DOI: 10.1520/D5980-16.2For referenced ASTM standards, visit the ASTM
15、 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.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes s
16、ection appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5753 Guide for Planning and Conducting Borehole Geo-physical LoggingD5787 Practice for Monitoring Well ProtectionD5903 Guide for Planning and P
17、reparing for a GroundwaterSampling EventD5979 Guide for Conceptualization and Characterization ofGroundwater Systems3. Terminology3.1 DefinitionsFor common definitions of technical termsused in this standard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 supply (
18、production) well, nwell primarily installedfor public supply, irrigation, and industrial use. Supply wellsmay be used as an observation well.4. Significance and Use4.1 This guide describes a general approach for the use ofexisting wells in environmental investigations with a primaryfocus on the subs
19、urface and major factors affecting the surfaceand subsurface environment.4.2 Existing wells represent a valuable source of informa-tion for subsurface environmental investigations. Specific usesof existing wells include:4.2.1 Well driller logs provide information on subsurfacelithology and major wat
20、er-bearing units in an area. Existingwells can also offer access for downhole geophysical loggingfor stratigraphic and aquifer interpretations. Examples includenatural gamma logs in cased wells and an entire suite ofmethods in uncased bedrock wells (see Guide D5753). Thisinformation can assist in de
21、veloping the preliminary concep-tual model of the site.4.2.2 Well tests using existing wells may provide informa-tion on the hydrologic characteristics of an aquifer.4.2.3 Monitoring of water levels in existing wells, providedthat they are cased in the aquifer of interest, allow developmentof potent
22、iometric maps and interpretations of groundwater flowdirections and gradients.4.2.4 Existing wells are the primary means by which re-gional drinking water quality is evaluated and monitored.4.2.5 Existing wells may assist in the mapping of contami-nant plumes, and in ongoing monitoring of groundwate
23、rquality changes at the site-specific level.4.3 Data from existing wells should only be used whencharacteristics of the well have been sufficiently documented todetermine that they satisfy criteria for the purpose for whichthe data are to be used.5. General Considerations in Selection and Use ofExis
24、ting Wells5.1 Selection and use of existing wells should take place inthe context of a conceptual framework consisting of a descrip-tion of the system, including, as necessary, physical andcultural characteristics, such as climate, hydrology, ecology,physiography, population, water use and land use,
25、 and hypoth-eses about processes of interest that occur within that system.A step-wise approach for conceptualization and characteriza-tion is a direct approach to develop the framework forHydrologic Systems as described in Kolm (1)4, (see GuideD5979). Conceptualization of hydrologic and regional gr
26、ound-water quality systems can be formulated using the methodsoutlined in Alley (2). The framework is reviewed and refinedby an iterative process of data collection and analysis, testinghypotheses with data collected, and identifying data needs tofurther revise the framework. Refinement must be made
27、 withinthe limits established by the accuracy, precision, and complete-ness of the data. Methods for data collection are selected thatwill provide data appropriate for testing hypotheses whichevaluate the conceptual framework.5.2 Well design and installation can greatly affect the qualityof groundwa
28、ter monitoring. Such effects apply both to existingwells and to wells specifically installed for a purpose. Theeffects of well design and installation, therefore, need to beconsidered regardless of whether existing wells are selected orif wells are specifically installed for a specific purpose. Them
29、ost common feature of an existing well that may render itunsuitable for water level measurement or water-quality moni-toring is that the well is completed in multiple hydrogeologicunits causing water levels and water-quality parameters toreflect a mixing of multiple hydrogeologic units. Such datacan
30、not be reliably compared with data from wells completed inthe individual hydrogeologic units.5.3 Major steps in the selection of existing wells forenvironmental investigations include: developing specific cri-teria for evaluating the suitability of existing wells in relationto the objectives of the
31、investigations (see Section 6), conduct-ing an inventory of existing wells in the area of interest (see8.1), documenting the characteristics of the wells identified inthe inventory that are relevant to the selection criteria (see 8.2),and identification of wells that satisfy the selection criteria (
32、seeSection 9).6. Well-Selection Criteria6.1 Assessing the suitability of existing wells for hydrologi-cal and groundwater quality studies requires development ofspecific well-selection criteria. The criteria are based onconsiderations of project objectives by defining the problem tobe solved, the co
33、nceptual framework, and data-collectionrequirements.6.2 Specific Well-Selection CriteriaSpecific criteria willdepend on the objectives of the investigation. The followinggeneral criteria will apply to most situations:6.2.1 The well is suitably located for use in relation to theconceptual framework.6
34、.2.2 The well must be completed in the targeted hydrogeo-logic unit or units.6.2.3 Well design and construction must not bias water levelmeasurements or water-quality sampling results (see Note 1).Section 7 provides information on the general characteristics ofmajor types of existing wells.NOTE 1Gil
35、lham et al. (3), provides information on the suitability of4The boldface numbers in parentheses refer to the list of references at the end ofthis standard.D5980 162materials coming in contact with water samples and that table providesinformation on the compatibility of well casing materials with dif
36、ferentorganic contaminants.6.2.4 The well is accessible for measurements and sam-pling.6.2.5 The wells maintenance condition may not compro-mise it as a sampling point; however, there are examples thatmay compromise it as a sampling point, that is, a crackedcasing allowing non-screened water into th
37、e well.6.3 Examples of Well Selection CriteriaThe following areillustrative examples of criteria for specific investigation ob-jectives (see Note 2).NOTE 2These are illustrative examples and should not be construed asrecommended criteria.6.3.1 A project to determine the quality of potable ground-wat
38、er might require the following selection criteria: wellsselected must be used for public water supply, must begeographically distributed over the entire aquifer of interest,and must be able to be sampled prior to any water treatment.6.3.2 All wells or a subset of wells down-gradient from ahazardous-
39、waste site would be unsuitable to include in anetwork designed for a study to determine non-point sourcegroundwater quality.6.3.3 Choosing a well located down-gradient of a complexmix of land uses would be inappropriate in a study designed toassess the effects of specific land uses on groundwater qu
40、ality.6.3.4 A supply well screened over a long interval would notbe appropriate for investigating small-scale vertical variationsin water quality down-gradient of a landfill, or for potentio-metric mapping.6.3.5 A well constructed of PVC (polyvinylchloride) withglued joints would not be suitable for
41、 sampling if the volatile-organic compounds of interest in the groundwater also arefound in the glue used to join the sections of well casing.Similarly, a well constructed of steel may not be suitable forthe sampling of metals.6.3.6 Selecting an observation well in an area undergoingrapid developmen
42、t would be avoided in constructing a networkof wells for evaluating long-term trends in groundwater qualitybecause of the possibility of the well being destroyed by laterdevelopment.7. General Characteristics of Major Types of ExistingWells7.1 There are two general categories of existing wellsavaila
43、ble for hydrologic and groundwater quality studies:large- and small-capacity supply or production wells installedfor drinking, irrigation, and industrial use (see 7.2 and 7.3); andwells specially designed and installed to monitor hydrologic orwater-quality studies, or both (see 7.4). Each type of we
44、ll hasits own general advantages and disadvantages.7.2 Large-Capacity Supply WellsLarge-capacity supplywells are usually developed for drinking water systems thatsupply multiple households, and for irrigation and industrialpurposes.7.2.1 Advantages:7.2.1.1 Documentation of well construction commonly
45、 isgood.7.2.1.2 Large-capacity wells generally are well developedand fully purged.7.2.1.3 Long-term access may be possible, particularly formunicipal wells.7.2.1.4 Large-capacity wells generally provide a larger ver-tical mix of water in an aquifer or aquifer system thansmall-capacity wells, and thu
46、s can provide a more integratedmeasure of regional groundwater quality than small-capacitywells.7.2.1.5 Much of the water produced for irrigation andmunicipal water is from large-capacity wells equipped withtaps which allow a direct sample of the pumped water.7.2.1.6 Long-term water-quality and quan
47、tity data may beavailable.7.2.2 Disadvantages:7.2.2.1 Large-capacity wells may not have flow-rate con-trols and a sampling point near the well head.7.2.2.2 High pumping rates may entrain artifacts, such ascolloids or suspended material, into the sample stream.7.2.2.3 Pumping schedules could be irreg
48、ular: for example,irrigation wells generally are pumped seasonally, and couldlead to seasonal variations in water quality that actually are anartifact of the pumping regime.7.2.2.4 Large capacity wells may have a long vertical gravelpack, screened or open intervals might span more than oneaquifer or
49、 aquifer system, making them unsuitable for poten-tiometric mapping or water quality monitoring. For example,dilution of contaminant concentrations wells with long screenintervals may result in large errors if concentrations are usedfor detailed delineation of the geometry and concentrations ofcontaminant plumes or for detection of contaminants in lowconcentrations (Pohlmann and Alduino (4).7.2.2.5 Wells with high pumping rates may draw water fromwater-bearing units other than those screened even if the wellis screened solely within one unit; thus, the vertical integrat
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