1、Designation: D 5978 96 (Reapproved 2005)Standard Guide forMaintenance and Rehabilitation of Ground-Water MonitoringWells1This standard is issued under the fixed designation D 5978; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th
2、e 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.INTRODUCTIONThis guide for maintenance and rehabilitation promotes procedures appropriate to ground-watermonitoring wel
3、ls 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 maintenance and rehabilitation program forground-water monitori
4、ng 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 samples from, and information about thehydraulic properties of
5、 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 restricted than for other types ofwells. Monitoring well
6、s 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 The values stated in SI units are to be regarded as thestandard.1.4 This standard do
7、es 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 applica-bility of regulatory limitations prior to use.1.5 This guide offers an organized
8、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 with professionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This ASTM standard
9、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 consideration of a projects manyunique aspects. The word “Standard” in the title of thisdocument means only that the document
10、has been approvedthrough the ASTM consensus process.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 1889 Test Method for Turbidity of WaterD 4044 Test Method for (Field Procedures) DeterminingInstantaneous Change in Head (Slug Tests) for Dete
11、rmin-ing Hydraulic Properties of AquifersD 4412 Test Methods for Sulfide Reducing Bacteria inWater and Water-Formed DepositsD 4448 Guide for Sampling Ground Water MonitoringWellsD 4750 Test Method for Determining Subsurface LiquidLevels in a Borehole or Monitoring Well (ObservationWell)D 5088 Practi
12、ce for Decontamination of Field EquipmentUsed at Nonradioactive Waste SitesD 5092 Practice for Design and Installation of GroundWater Monitoring Wells in AquifersD 5254 Practice for the Minimum Set of Data Elements toIdentify a Ground-Water SiteD 5299 Guide for the Decommissioning of Ground WaterWel
13、ls, Vadose Zone Monitoring Devices, Boreholes, andOther Devices for Environmental ActivitiesD 5408 Guide for the Set of Data Elements to Describe a1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Ground Water andVad
14、ose Zone Investigations.Current edition approved Jan. 1, 2005. Published February 2005. Originallyapproved in 1996. Last previous edition approved in 1996 as D 597896.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
15、Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Ground-Water Site; Part 1Additional Identification De-scriptorsD 5409 Guide for
16、 the Set of Data Elements to Describe aGround-Water Site; Part 2Physical DescriptorsD 5410 Guide for the Set of Data Elements to Describe aGround-Water Site; Part 3Usage DescriptorsD 5472 Test Method for Determining Specific Capacity andEstimating Transmissivity at the Control WellD 5474 Guide for S
17、election of Data Elements for Ground-Water InvestigationsD 5521 Guide for Development of Ground Water Monitor-ing Wells in Granular Aquifers2.1.1 In addition, ASTM Volume 11.01 on Water (I) andVolume 11.02 on Water (II) contain numerous test methodsand standards that may be of value to the user of t
18、his guide.3. Terminology3.1 Definitions:3.1.1 Except where noted, all terms and symbols in thisguide are in accordance with the following publications in theirorder of consideration:3.1.1.1 Terminology D 653,3.1.1.2 Guide D 5521,3.1.1.3 Compilation of ASTM Standard Terminology, 7thEdition, 1990, and
19、3.1.1.4 Websters Ninth New Collegiate Dictionary, 1989.3.2 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
20、 that might affect the wells 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 ground water surrounding it. Mainten
21、anceincludes both physical 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 maintena
22、nceany well maintenanceaction 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
23、-ment of a major component (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 wel
24、lspresence and operation over 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 maintenanceanywe
25、ll maintenance action that 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 deter
26、ioration. Lack of or improper 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 m
27、aterials, and installed to evaluatecontamination that can cause locally anomalous hydro-geochemical conditions. The typical solutions for these physi-cal and chemical problems that would be applied by ownersand operators of water supply, dewatering, recharge, and otherwells may not be appropriate fo
28、r monitoring wells because ofthe 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.
29、4.3 The design of maintenance 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 the
30、references provided.4.4 For additional information see Test Methods D 1889,D 4412, D 5472, and Guides D 4448, D 5409, D 5410 andD 5474.5. Well Performance Deficiencies5.1 Proper well design, installation, and development canminimize well performance deficiencies that result in the needfor maintenanc
31、e and rehabilitation. Practice D 5092 and GuideD 5521 should be consulted. Performance deficiencies include:sand, silt, and clay infiltration; low yield; slow responses tochanges in ground-water elevations; and loss of production.5.2 Preventable Causes of Poor Well Performance:5.2.1 Inappropriate we
32、ll location or screened interval. Thesemay 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, filter ma-terial, and so forth),5.2.4 Inappropriate w
33、ell construction materials. This maylead 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,5.2.7 Inappropriate pump selection, and5.2.8 Introducti
34、on of foreign substances.5.3 Physical Indicators of Well Performance DeficienciesInclude:D 5978 96 (2005)25.3.1 Sand, Silt, and Clay InfiltrationCauses include in-appropriate and inadequate well drilling (for example, augerflight smearing), improper screen and filter pack, impropercasing design or i
35、nstallation, incomplete development, screencorrosion, 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
36、.5.3.2 Low YieldCauses include dewatering, 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 interferenc
37、e, and chemical or micro-bial plugging or 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 unsupporte
38、d casing (that is, in caves orbecause of faulty grout), corrosion and subsequent failure ofscreen and casing, improper casing design, local site opera-tions, freeze-thaw, or improper chemical or mechanical reha-bilitation.5.3.5 Observation of physical damage or other indicator.6. Sample Quality Degr
39、adation6.1 All of the preceding physical well 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 c
40、hange inwell or aquifer chemistry that results 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 ormagnesiu
41、m carbonate or sulfate, iron, or sulfide compoundscan 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.
42、Biofouling may be accompa-nied by corrosion 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, g
43、alvanized steel, carbon steel,and low carbon 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 solven
44、ts may degrade PVC and otherplastics. Other 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
45、 of monomers (such asvinyl chloride) to the 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 corro
46、sion at less extremevalues. Expression of corrosion 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 purg
47、ing and sampling proceduresand devices used 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 inc
48、rease turbidity.6.2.5 Change in Sand/Silt Content 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 pr
49、oceduresand devices used can affect the sand/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 Ground WaterSamples)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 i
