1、Designation: D5978 96 (Reapproved 2011)1Standard Guide forMaintenance and Rehabilitation of Groundwater MonitoringWells1This standard is issued under the fixed designation D5978; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、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.1NOTEEditorial changes were made throughout in December 2011.INTRODUCTIONThis guide for maintenance and rehabilitation pro
3、motes procedures appropriate to groundwatermonitoring wells installed to evaluate the extent and nature of contamination, progress of remediation,and for long-term monitoring of either water quality or water level.1. Scope1.1 This guide covers an approach to selecting and imple-menting a well mainte
4、nance and rehabilitation program forgroundwater monitoring wells. It provides information onsymptoms of problems or deficiencies that indicate the need formaintenance and rehabilitation. It is limited to monitoringwells, that are designed and operated to provide access to,representative water sample
5、s from, and information about thehydraulic properties of the saturated subsurface while minimiz-ing impact on the monitored zone. Some methods describedherein may apply to other types of wells although the range ofmaintenance and rehabilitation treatment methods suitable formonitoring wells is more
6、restricted than for other types ofwells. Monitoring wells include their associated pumps andsurface equipment.1.2 This guide is affected by governmental regulations andby site specific geological, hydrogeological, geochemical,climatological, and biological conditions.1.3 This standard does not purpo
7、rt 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 applica-bility of regulatory limitations prior to use.1.4 This guide offers an organized collection o
8、f 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 with professionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This ASTM standard is not inten
9、ded 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 consideration of a projects manyunique aspects. The word “Standard” in the title of thisdocument means only that the document has been app
10、rovedthrough the ASTM consensus process.2. Referenced Documents2.1 ASTM Standards:2D652 Method of Test for Measuring Mica Stampings Usedin Electronic Devices and Incandescent Lamps (With-drawn 1956)3D653 Terminology Relating to Soil, Rock, and ContainedFluidsD1889 Test Method for Turbidity of Water
11、(Withdrawn2007)3D4044 Test Method for (Field Procedure) for InstantaneousChange in Head (Slug) Tests for Determining HydraulicProperties of AquifersD4412 Test Methods for Sulfate-Reducing Bacteria in Waterand Water-Formed DepositsD4448 Guide for Sampling Ground-Water Monitoring WellsD4750 Test Metho
12、d for Determining Subsurface LiquidLevels in a Borehole or Monitoring Well (ObservationWell) (Withdrawn 2010)3D5088 Practice for Decontamination of Field EquipmentUsed at Waste Sites1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcomm
13、ittee D18.21 on Groundwater andVadose Zone Investigations.Current edition approved Dec. 1, 2011. Published December 2012. Originallyapproved in 1996. Last previous edition approved in 2005 as D597896(2005).DOI: 10.1520/D5978-96R11E1.2For referenced ASTM standards, visit the ASTM website, www.astm.or
14、g, 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.Copyright ASTM International, 100 Barr Harbo
15、r Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5092 Practice for Design and Installation of Ground WaterMonitoring WellsD5254 Practice for Minimum Set of Data Elements toIdentify a Ground-Water SiteD5299 Guide for Decommissioning of Groundwater Wells,Vadose Zone Monitoring De
16、vices, Boreholes, and OtherDevices for Environmental ActivitiesD5408 Guide for Set of Data Elements 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
17、Elements to Describe aGround-Water Site;Part ThreeUsage DescriptorsD5472 Test Method for Determining Specific Capacity andEstimating Transmissivity at the Control WellD5474 Guide for Selection of Data Elements for Groundwa-ter InvestigationsD5521 Guide for Development of Ground-Water MonitoringWells
18、 in Granular Aquifers2.1.1 In addition, ASTM Volume 11.01 on Water (I) andVolume 11.02 on Water (II) contain numerous test meth-ods and standards that may be of value to the user of thisguide.3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms in thisstandard, refer to Term
19、inology D652 and Guide D5521.3.2 Definitions of Terms Specific to This Standard:3.2.1 well developmentactions taken during the installa-tion and start-up of a well for the purpose of mitigating orcorrecting damage done to the adjacent geologic formationsand filter materials that might affect the wel
20、ls ability toproduce representative samples.3.2.2 well maintenanceany action that is taken for thepurpose of maintaining well performance (see Discussion) andextending the life of the well to provide samples that arerepresentative of the groundwater surrounding it. Maintenanceincludes both physical
21、actions taken at the well and thedocumentation of those actions and all operating data in orderto provide benchmarks for comparisons at later times.3.2.2.1 DiscussionDesired level of well performance canvary depending on the design objectives.3.2.3 well preventive maintenanceany well maintenanceacti
22、on that is initiated for the purpose of meeting somepreestablished rule or schedule that applies while well perfor-mance is still within preestablished ranges.3.2.4 well reconstructive maintenanceany preventive orrehabilitative well maintenance action involving the replace-ment of a major component
23、(for example, pump, surfaceprotection).3.2.5 well redevelopmentany preventive or rehabilitativewell maintenance action, taken after start-up, for the purpose ofmitigating or correcting deterioration of the filter pack oradjacent geologic formations, or both, due to the wellspresence and operation ov
24、er time, usually involving physicaldevelopment procedures, applied in reaction to deterioration.3.2.6 well rehabilitationfor the purposes of this guide,synonymous with well rehabilitative or restorative mainte-nance.3.2.7 well rehabilitative or restorative maintenanceanywell maintenance action that
25、is initiated for the purpose ofcorrecting well performance that has moved outside of prees-tablished ranges.4. Significance and Use4.1 The process of operating any engineered system, such asmonitoring wells, includes active maintenance to prevent,mitigate, or reverse deterioration. Lack of or improp
26、er main-tenance can lead to well performance deficiencies (physicalproblems) or sample quality degradation (chemical problems).These problems are intrinsic to monitoring wells, which areoften left idle for long periods of time (as long as a year),installed in non-aquifer materials, and installed to
27、evaluatecontamination that can cause locally anomalous hydrogeo-chemical conditions. The typical solutions for these physicaland chemical problems that would be applied by owners andoperators of water supply, dewatering, recharge, and otherwells may not be appropriate for monitoring wells because of
28、the need to minimize their impact on the conditions thatmonitoring wells were installed to evaluate.4.2 This guide covers actions and procedures, but is not anencyclopedic guide to well maintenance. Well maintenanceplanning and execution is highly site and well specific.4.3 The design of maintenance
29、 and rehabilitation programsand the identification of the need for rehabilitation should bebased on objective observation and testing, and by individualsknowledgeable and experienced in well maintenance andrehabilitation. Users of this guide are encouraged to consult thereferences provided.4.4 For a
30、dditional information see Test Methods D1889,D4412, D5472, and Guides D4448, D5409, D5410 and D5474.5. Well Performance Deficiencies5.1 Proper well design, installation, and development canminimize well performance deficiencies that result in the needfor maintenance and rehabilitation. Practice D509
31、2 and GuideD5521 should be consulted. Performance deficiencies include:sand, silt, and clay infiltration; low yield; slow responses tochanges in groundwater elevations; and loss of production.5.2 Preventable Causes of Poor Well Performance:5.2.1 Inappropriate well location or screened interval. Thes
32、emay be unavoidable if a requirement for site characterization ormonitoring exists,5.2.2 Inappropriate drilling technique or methodology formaterials screened,5.2.3 Inadequate intake structure design (screen, filtermaterial, and so forth),5.2.4 Inappropriate well construction materials. This maylead
33、 to corrosion or collapse,5.2.5 Improper construction, operation, or maintenance, orcombination thereof, of borehole or well, wellhead protection,well cap, and locking device,5.2.6 Ineffective development,D5978 96 (2011)125.2.7 Inappropriate pump selection, and5.2.8 Introduction of foreign substance
34、s.5.3 Physical Indicators of Well Performance DeficienciesInclude:5.3.1 Sand, Silt, and Clay InfiltrationCauses include in-appropriate and inadequate well drilling (for example, augerflight smearing), improper screen and filter pack, impropercasing design or installation, incomplete development, scr
35、eencorrosion, or collapse of filterpack. In rock wells, causesinclude the presence of fine material in fractures. The presenceof sand, silt, or clay can result in pump and equipment wearand plugging, turbid samples, filterpack plugging, or combina-tion thereof.5.3.2 Low YieldCauses include dewaterin
36、g, collapse orconsolidation of fracture or water-bearing zone, pump mal-function or plugging, screen encrustation or plugging, andpump tubing corrosion or perforation.5.3.3 Water Level DeclineCauses include area or regionalwater level decline, well interference, and chemical or micro-bial plugging o
37、r encrustation of the borehole, screen, orfilterpack.5.3.4 Loss of ProductionUsually caused by pump failure,but can also be caused by dewatering, plugging, or wellcollapse.5.3.4.1 Well CollapseCan be caused by tectonism, groundsubsidence, failure of unsupported casing (that is, in caves orbecause of
38、 faulty grout), corrosion and subsequent failure ofscreen and casing, improper casing design, local siteoperations, freeze-thaw, or improper chemical or mechanicalrehabilitation.5.3.5 Observation of physical damage or other indicator.6. Sample Quality Degradation6.1 All of the preceding physical wel
39、l performance deficien-cies can result in sample quality degradation by dilution,cross-contamination, or entrainment of solid material in watersamples. In addition, chemical and biological activity can bothdegrade well performance and sample quality. Any change inwell or aquifer chemistry that resul
40、ts from the presence of thewell can interfere with accurate characterization of a site.6.2 Physical IndicatorsChemical and biological activitythat can lead to sample quality degradation include:6.2.1 Chemical EncrustationPrecipitation of calcium ormagnesium carbonate or sulfate, iron, or sulfide com
41、poundscan reduce well yield and specific capacity.6.2.2 Biofouling (Biological Fouling)Microbial activitycan result in slime production and the precipitation of iron,manganese, or sulfur compounds and occasionally other ma-terials such as aluminum oxides. Biofouling may be accompa-nied by corrosion
42、or encrustation, or both, and can result inreduced specific capacity and well yield. Biochemical depositscan interfere with sample quality by acting as chemical sieves.6.2.3 CorrosionCorrosion of metal well and pump com-ponents (that is, stainless steel, galvanized steel, carbon steel,and low carbon
43、 steel) can result from naturally aggressivewaters (containing H2S, NaCl) or electrolysis. The presence ofcontaminants contributes to corrosion through contributions tomicrobial corrosion processes and formation of redox gradi-ents. Nonaqueous phase solvents may degrade PVC and otherplastics. Other
44、environmental conditions such as heat orradiation may contribute to material deterioration (such asenhanced embrittlement). Metals such as nickel or chromiummay be leached from corroding metals. Degradation of plasticwell components may result in a release of monomers (such asvinyl chloride) to the
45、environment (see Note 1).NOTE 1Naturally aggressive (for metals) waters have been defined aslow pH (2 mg/L), high H2S (1 mg/L), high dissolvedsolids (1000 mg/L), high CO2(50 mg/L), and high Clcontent (500mg/L). However, local conditions may result in corrosion at less extremevalues. Expression of co
46、rrosion is also dependent on materials load.6.2.4 Change in TurbidityCauses include biofouling andintake structure, screen or filter pack clogging or collapse.Increase in turbidity may not always be the result of a problemwith the well. Changes in the purging and sampling proceduresand devices used
47、can affect the turbidity of water from amonitoring well. For example, using a bailer where a pumpwas previously utilized, or pumping at a higher rate thanpreviously used could increase turbidity; likewise, pumping awell that was previously bailed could increase turbidity.6.2.5 Change in Sand/Silt Co
48、ntent or Particle CountsCauses include biofouling (resulting in clogging or sloughing)and intake structure clogging or collapse. Increase in thesand/silt content may not always be the result of a problemwith the well. Changes in the purging and sampling proceduresand devices used can affect the sand
49、/silt content of water froma monitoring well. For example, using a bailer where a pumpwas previously utilized, or pumping at a higher rate thanpreviously used could increase the sand/silt content; likewise,pumping a well that was previously bailed could increase thesand/silt content.6.3 Chemical Indicators (Observed in GroundwaterSamples)Chemical and biological activity that can lead tosample quality degradation include (see Note 2):NOTE 2Changes in chemical indicators can also be a result ofsite-wide changes in hydro-geochemistry.6.3.1 Iron (Changes
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