1、Designation: D 5980 96 (Reapproved 2004)Standard Guide forSelection and Documentation of Existing Wells for Use inEnvironmental Site Characterization and Monitoring1This standard is issued under the fixed designation D 5980; the number immediately following the designation indicates the year oforigi
2、nal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers the use of existing wells for environ-mental
3、site characterization and monitoring. It covers thefollowing major topics: criteria for determining the suitabilityof existing wells for hydrogeologic characterization andground-water quality monitoring, types of data required todocument the suitability of an existing well, and the relativeadvantage
4、s and disadvantages of existing large- and small-capacity wells.1.2 This guide should be used in conjunction with GuideD 5730, that provides a general approach for environmentalsite investigations.1.3 This guide does not specifically address design andconstruction of new monitoring or supply wells.
5、Refer toPractices D 5092 and D 5787.1.4 This guide does not specifically address ground-watersampling procedures. Refer to Guide D 5903.1.5 The values stated in SI units are to be regarded as thestandard. However, dimensions of materials used in the waterwell industry are given in inch-pound (Englis
6、h) units byconvention; therefore, inch-pound units are used where neces-sary in this guide.1.6 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 practi
7、ces 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 and does not recommend a specificcourse of action. This guide cannot replace education orexperience and should be used in conjunction with pr
8、ofessionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This guide is not intended to represent orreplace the standard of care by which the adequacy of a givenprofessional service must be judged, nor should this guide beapplied without consideration of a projects man
9、y uniqueaspects. The word “Standard” in the title of this documentmeans only that the document has been approved through theASTM consensus process.2. Referenced Documents2.1 Pertinent guides addressing specific information neces-sary to utilize existing wells for hydrologic and water-qualitydata for
10、 environmental site characterization. A comprehensivelist of guides, standards, methods, practices, and terminology iscontained in Guide D 5730. Other guidance documents cover-ing procedures for environmental site investigations withspecific objectives or in particular geographic settings may beavai
11、lable from federal, state, and other agencies or organiza-tions. The appropriate agency or organization should becontacted to determine the availability and most current editionof such documents.2.2 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 4750 Test Method for D
12、etermining Subsurface LiquidLevels in a Borehole or Monitoring Well (ObservationWell)D 5092 Practice for Design and Installation of GroundWater Monitoring Wells in AquifersD 5254 Practice for a Minimum Set of Data Elements toIdentify a Ground-Water SiteD 5408 Guide for Set of Data Elements to Descri
13、be aGround-Water Site; Part OneAdditional IdentificationDescriptorsD 5409 Guide for Set of Data Elements to Describe aGround-Water Site; Part TwoPhysical DescriptorsD 5410 Guide for Set of Data Elements to Describe aGround-Water Site; Part ThreeUsage DescriptorsD 5474 Guide for Selection of Data Ele
14、ments for Ground-Water InvestigationsD 5521 Guide for Development of Ground-Water Monitor-ing Wells in Granular Aquifers3D 5730 Guide for Site Characterization for Environmental1This guide is under the jurisdiction of ASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommitte
15、e D18.21 on Ground Water andVadose Zone Investigations.Current edition approved May 1, 2004. Published May 2004. Originallyapproved in 1996. Last previous edition approved in 1996 as D 5980 - 96e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service a
16、t serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Purposes with Emphasis on Soil, Rock,
17、the Vadose Zoneand Ground WaterD 5753 Guide for Planning and Conducting Borehole Geo-physical LoggingD 5787 Practice for Monitoring Well ProtectionD 5903 Guide for Planning and Preparing for a Groundwa-ter Sampling EventD 5978 Guide for Maintenance and Rehabilitation ofGround-Water Monitoring WellsD
18、 5979 Guide for Conceptualization and Characterizationof Ground-Water Systems3. Terminology3.1 DefinitionsExcept as noted below, all definitions arein accordance with Terminology D 653:3.1.1 aquifer, na geologic formation, group of forma-tions, or part of a formation that is saturated and is capable
19、 ofproviding a significant quantity of water (see Practice D 5092).3.1.2 monitoring well (observation well), na special welldrilled in a selected location for observing parameters such asliquid level or pressure changes or for collecting liquidsamples. The well may be cased or uncased, but if cased,
20、 thecasing should have openings to allow flow of borehole liquidinto or out of the casing.3.1.3 observation well, nfor the purposes of this guide, anexisting well constructed for other purposes that is also used tomeasure water levels and to collect ground-water qualitysamples. Observation well may
21、be referred to as “well” in thisguide.3.1.4 supply (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 environm
22、ental investigations with a primaryfocus on the subsurface 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 prov
23、ide information on subsurfacelithology and major water-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
24、 (see Guide D 5753). Thisinformation can assist in developing 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 i
25、n the aquifer of interest, allow developmentof potentiometric maps and interpretations of ground-waterflow directions.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,
26、 and in ongoing monitoring of ground-waterquality 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 C
27、onsiderations in Selection and Use ofExisting 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,physiogr
28、aphy, population, water use and land use, 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 GuideD 5979). Conce
29、ptualization of hydrologic and regionalground-water quality systems can be formulated using themethods outlined in Alley (2). The framework is reviewed andrefined by an iterative process of data collection and analysis,testing hypotheses with data collected, and identifying dataneeds to further revi
30、se the framework. Refinement must bemade within the limits established by the accuracy, precision,and completeness of the data. Methods for data collection areselected that will provide data appropriate for testing hypoth-eses which evaluate the conceptual framework.5.2 Well design and installation
31、can critically affect thequality of water level measurements and ground-watersamples. Such effects apply both to existing wells and to wellsspecifically installed for a purpose. The effects of well designand installation, therefore, need to be considered regardless ofwhether existing wells are selec
32、ted or if wells are specificallyinstalled for a specific purpose. The most common feature of anexisting well that may render it unsuitable for water levelmeasurement or water-quality monitoring is that multiplehydrogeologic units are connected causing water levels andwater-quality parameters to refl
33、ect a mixing of multiple hydro-geologic units. Such data cannot be reliably compared withdata from wells completed in the individual hydrogeologicunits.5.3 Major steps in the selection of existing wells forenvironmental investigations include: developing specific cri-teria for evaluating the suitabi
34、lity of existing wells in relationto the objectives of the 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 id
35、entification of wells that satisfy the selection criteria (seeSection 9).6. Well-Selection Criteria6.1 Assessing the suitability of existing wells for hydrologi-cal and ground-water quality studies requires development of4The boldface numbers in parentheses refer to the list of references at the end
36、 ofthis standard.D 5980 96 (2004)2specific well-selection criteria. The criteria are based onconsiderations of project objectives by defining the problem tobe solved, the conceptual framework, and data-collectionrequirements.6.2 Specific Well-Selection CriteriaSpecific criteria willdepend on the obj
37、ectives 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.6.2.2 The well must be completed in the targeted hydrogeo-logic unit or units.6.2.3 Well design and construction must not bias w
38、ater levelmeasurements or water-quality sampling results (see Note 1).Section 7 provides information on the general characteristics ofmajor types of existing wells.NOTE 1Gillham et al. (3), provides information on the suitability ofmaterials coming in contact with water samples and that table provid
39、esinformation on the compatibility of well casing materials with differentorganic 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
40、 point, that is, a crackedcasing allowing non-screened water into the 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 construedas recommended cri
41、teria.6.3.1 A project to determine the quality of potable groundwater 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.
42、6.3.2 All wells or a subset of wells down-gradient from ahazardous-waste site would be unsuitable to include in anetwork designed for a study to determine non-point sourceground-water quality.6.3.3 Choosing a well located down-gradient of a complexmix of land uses would be inappropriate in a study d
43、esigned toassess the effects of specific land uses on ground-water quality.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
44、of PVC (polyvinylchloride) withglued joints would not be suitable for sampling if the volatile-organic compounds of interest in the ground water 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
45、.6 Selecting an observation well in an area undergoingrapid development would be avoided in constructing a networkof wells for evaluating long-term trends in ground-waterquality because of the possibility of the well being destroyedby later development.7. General Characteristics of Major Types of Ex
46、istingWells7.1 There are two general categories of existing wellsavailable for hydrologic and ground-water 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 monito
47、r hydrologic orwater-quality studies, or both (see 7.4). Each type of well 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 industrialpurpo
48、ses.7.2.1 Advantages:7.2.1.1 Documentation of well construction commonly 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
49、 water in an aquifer or aquifer system thansmall-capacity wells, and thus can provide a more integratedmeasure of regional ground-water 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 quantity 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 a
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