1、Designation: D7048 04 (Reapproved 2010)Standard Guide forApplying Statistical Methods for Assessment and CorrectiveAction Environmental Monitoring Programs1This standard is issued under the fixed designation D7048; the number immediately following the designation indicates the year oforiginal adopti
2、on or, in 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. Scope1.1 The scope and purpose of this guidance is to present avariety of statistic
3、al approaches for assessment, complianceand corrective action environmental monitoring programs.Although the methods provided here are appropriate and oftenoptimal for many environmental monitoring problems, they donot preclude use of other statistical approaches that may beequally or even more usef
4、ul for certain site-specific applica-tions.1.2 In the following sections, complete details of selectstatistical procedures used in assessment and corrective actionprograms for environmental monitoring (soil, ground water,air, surface water, and waste streams) are presented.1.3 The statistical method
5、ology described in the followingsections should be used as guidance. Other methods may alsobe appropriate based on site-specific conditions or for moni-toring situations or media that are not presented in thisdocument.1.4 This practice offers an organized collection of informa-tion or a series of op
6、tions and does not recommend a specificcourse of action. This document cannot replace education,experience and professional judgements. Not all aspects of thispractice may be applicable in all circumstances. This ASTMstandard is not intended to represent or replace the standard ofcare by which the a
7、dequacy of a given professional servicemust be judged without consideration of a projects manyunique aspects. The word Standard in the title of this documentonly means that the document has been approved through theASTM consensus process.1.5 This standard does not purport to address all of thesafety
8、 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 requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2D5092 Practice for Design and Ins
9、tallation of GroundWaterMonitoring WellsD5792 Practice for Generation of Environmental Data Re-lated to Waste Management Activities: Development ofData Quality ObjectivesD6250 Practice for Derivation of Decision Point and Con-fidence Limit for StatisticalTesting of Mean Concentrationin Waste Managem
10、ent DecisionsD6312 Guide for Developing Appropriate Statistical Ap-proaches for Ground-Water Detection Monitoring Pro-grams3. Terminology3.1 Definitions:3.1.1 assessment monitoringinvestigative monitoring thatis initiated after the presence of a contaminant has beendetected in ground water above a r
11、elevant criterion at one ormore locations. The objective of the program is to determine ifthere is a statistical exceedance of a standard or criteria at aPotential Area of Concern (PAOC) or at the ground waterdischarging to surface water interface, and/or to quantify therate and extent of migration
12、of constituents detected in groundwater above applicable criteria.3.1.2 compliance monitoringas specified under 40 CFR264.99, compliance monitoring is instituted when hazardousconstituents have been detected above a relevant criterion atthe compliance point during RCRA detection monitoring.Ground-wa
13、ter samples are collected at the compliance point,facility property boundary, and upgradient monitoring wells foranalysis of hazardous constituents to determine if they areleaving the regulated unit at statistically significant concentra-tions above background.3.1.3 corrective action monitoringunder
14、 RCRA, correc-tive action monitoring is instituted when hazardous constitu-ents from a RCRA regulated unit have been detected at1This guide is under the jurisdiction ofASTM Committee D18 on Soil and Rockand is the direct responsibility of Subcommittee D18.21 on Ground Water andVadose Zone Investigat
15、ions.Current edition approved July 1, 2010. Published September 2010. Originallyapproved in 2004. Last previous edition approved in 2004 as D704804. DOI:10.1520/D7048-04R10.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For A
16、nnual 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.statistically significant concentrations between the compliancepoint and
17、the downgradient facility property boundary asspecified under 40 CFR 264.100. Corrective action monitoringis conducted throughout a corrective action program that isimplemented to address ground-water contamination. At non-RCRA sites, corrective action monitoring is conductedthroughout the active pe
18、riod of corrective action to determinethe progress of remediation and to identify statistically signifi-cant trends in ground-water contaminant concentrations.3.1.4 detection limit, DLthe true concentration at whichthere is a specified level of confidence (for example, 99 %confidence) that the true
19、concentration is greater than zero.3.1.5 detection monitoringa program of monitoring forthe express purpose of determining whether or not there hasbeen a release of a contaminant to ground water. Under RCRA,Detection Monitoring involves collection of ground-watersamples from compliance point and upg
20、radient monitoringwells on a semi-annual basis for analysis of hazardous con-stituents of concern, as specified under 40 CFR 264.98. Resultsare evaluated to determine if there is a statistically significantexceedance of the ground-water protection criterion and/orbackground. At non-RCRA sites, monit
21、oring is conducted in asimilar manner and results are compared to criteria to deter-mine if there is a statistically significant exceedance.3.1.6 direct push samplingground-water sampling con-ducted with a device that is temporarily pushed into the groundwith a hydraulic system or with a hammer. Aft
22、er ground-watersample collection, the device is removed from the ground.Examples include Geoprobet, Hydropuncht direct push, andenvironmental soil probe.3.1.7 false negative ratethe rate at which the statisticalprocedure does not indicate contamination when contamina-tion is present.3.1.8 false posi
23、tive ratethe rate at which the statisticalprocedure indates contamination when contamination is notpresent.3.1.9 lognormal distributiona frequency distributionwhose logarithm follows a normal distribution.3.1.10 lower confidence limit, LCLa lower limit that has aspecified probability (for example, 9
24、5 %) of including the trueconcentration (or other parameter). Taken together with theupper confidence limit, forms a confidence interval that willinclude the true concentration with confidence level thataccounts for both tail areas (for example, 90 %).3.1.11 lower prediction limit, LPLa statistical
25、estimate ofthe minimum concentration that will provide a lower bound forthe next series of k measurements from that distribution, or themean of m new measurements for each of k sampling locations,with specified level of confidence (for example, 95 %).3.1.12 nonparametrica term referring to a statist
26、ical tech-nique in which the distribution of the constituent in thepopulation is unknown and is not restricted to be of a specifiedform.3.1.13 nonparametric prediction limitthe largest (or sec-ond largest) of n background samples. The confidence levelassociated with the nonparametric prediction limi
27、t is a functionof n, m and k.3.1.14 normal distributiona frequency distribution whoseplot is a continuous, infinite, bell-shaped curve that is sym-metrical about its arithmetic mean, mode and median (whichare numerically equivalent). The normal distribution has twoparameters, the mean and variance.3
28、.1.15 outliera measurement that is statistically inconsis-tent with the distribution of other measurements from which itwas drawn.3.1.16 parametrica term referring to a statistical tech-nique in which the distribution of the constituent in thepopulation is assumed to be known.3.1.17 quantification l
29、imit, QLa lower limit on the con-centration at which quantitative determinations of an analytesconcentration in the sample can be reliably made duringroutine laboratory operating conditions. The QL is typicallydescribed quantitatively as the true concentration at which thesignal to noise ratio of me
30、asured concentration or instrumentresponse is 10:1. The signal to noise ratio is often determinedby a percent relative standard deviation of 10 %.3.1.18 potential area of concernareas with a documentedrelease or likely presence of a hazardous substance that couldpose an unacceptable risk to human he
31、alth or the environment.3.1.19 phase I environmental site assessmentnon-intrusive investigation that identifies PAOCs which may re-quire further investigation in subsequent phases of work.3.1.20 phase II environmental site assessment, ESIintrusive survey to confirm or deny existence of a release int
32、othe environment at a PAOC at levels which may adverselyimpact public health or the environment.3.1.21 upper confidence limit, UCLan upper limit that hasa specified probability (for example, 95 %) of including thetrue concentration (or other parameter). Taken together withthe lower confidence limit,
33、 the UCL forms a confidenceinterval that will include the true concentration with confidencelevel that accounts for both tail areas.3.1.22 upper prediction limit, UPLa statistical estimate ofthe maximum concentration that will not be exceeded by thenext series of k measurements from that distributio
34、n, or themean of m new measurements for each of k sampling locations,with specified level of confidence (for example, 95 %) basedon a sample of n background measurements.3.2 Symbols: = the true population mean of a constituentx= the sample-based mean or average concentration of aconstituent computed
35、 from n background measurements whichdiffers from because of sampling variability, and other errors2= the true population variance of a constituents2= the sample-based variance of a constituent computedfrom n background measurementss = the sample-based standard deviation of a constituentcomputed fro
36、m n background measurementsy= the mean of the natural log transformed data (also thenatural log of the geometric mean)sy= the standard deviation of the natural log transformeddatan = the number of background (offsite or upgradient) mea-surementsD7048 04 (2010)2k = the number of future comparisons fo
37、r a single monitor-ing event (for example, the number of downgradient monitor-ing wells multiplied by the number of constituents to bemonitored) for which statistics are to be computeda = the false positive rate for an individual comparison (thatis, one sampling location and constituent)m = the numb
38、er of onsite or downgradient measurementsused in computing the onsite mean concentrationa* = the site-wide false positive rate covering all samplinglocations and constituentst = the 100(1 a) percentage point of Studentst-distribution on n 1 degrees of freedomHL= the factor developed by Land (1971) (
39、1)3to obtain thelower 100(a) % confidence limit for the mean of a lognormaldistributionHU= the factor developed by Land (1971) (1) to obtain theupper 100(a) % confidence limit for the mean of a lognormaldistribution4. Summary of Guide4.1 The guide is summarized as Figs. 1-7. These figuresprovides a
40、flow-chart illustrating the steps used in computingthe comparisons to regulatory or health based ground-waterprotection standard (GWPS) in assessment and correctiveaction environmental monitoring programs.5. Significance and Use5.1 The principal use of this standard is in assessment,compliance and c
41、orrective action environmental monitoringprograms (for example, for any facility that could potentiallycontaminate ground water). The significance of the guidance isthat it presents a statistical method that allows comparison ofground-water data to regulatory and/or health based limits.5.2 Of course
42、, there is considerable USEPA support forstatistical methods applied to detection, assessment and cor-rective action monitoring programs that can be applied toenvironmental investigations. For example, the 90 % upperconfidence limit (UCL) of the mean is used in SW846 (Chapter9) for determining if a
43、waste is hazardous. If the UCL is lessthan the criterion for a particular hazardous waste code, thenthe waste is not a hazardous waste even if certain individualmeasurements exceed the criterion. Similarly, in the USEPAStatisticalAnalysis of Groundwater Monitoring Data at RCRAFacilities Addendum to
44、the Interim Final Guidance (1992) (2),confidence intervals for the mean and various upper percentilesof the distribution are advocated for assessment and correctiveaction. Interestingly, both the 1989 and 1992 USEPA guidancedocuments (2, 3) suggest use of the lower 95 % confidencelimit (LCL) as a to
45、ol for determining whether a criterion hasbeen exceeded in assessment monitoring. The latest USEPAguidance in this area (that is, the draft USEPA UnifiedStatistical Guidance) calls for use of the LCL in assessmentmonitoring and the UCL in corrective action. In this way,corrective action is only trig
46、gered if there is a high degree ofconfidence that the true concentration has exceeded the crite-rion or standard, whereas corrective action continues untilthere is a high degree of confidence that the true concentrationis below the criterion or standard. This is the general approachadopted in this g
47、uide, as well.5.3 There are several reasons why statistical methods areessential in assessment and corrective action monitoring pro-grams. First, a single measurement indicates very little aboutthe true concentration in the sampling location of interest, andwith only one sample there is no way of kn
48、owing if themeasured concentration is a typical or an extreme value. Theobjective is to compare the true concentration (or some intervalthat contains it) to the relevant criterion or standard. Second, inmany cases the constituents of interest are naturally occurring(for example, metals) and the natu
49、rally existing concentrationsmay exceed the relevant criteria. In this case, the relevantcomparison is to background (for example, off-site soil orupgradient ground water) and not to a fixed criterion. As such,background data must be statistically characterized to obtain astatistical estimate of an upper bound for the naturally occur-ring concentrations so that it can be confidently determined ifonsite concentrations are above background levels. Third, thereis often a need to compare numerous potential constituents ofconcern to criteria or background
