NPDES Compliance Inspection Manual

Transcription

NPDES ComplianceInspection ManualChapter 5EPA Publication Number: 305-K-17-001Interim Revised Version, January 2017

U.S. EPA Interim Revised NPDES Inspection Manual 2017CHAPTER 5 –SAMPLINGContentsA. Evaluation of Permittee Sampling Program and Compliance Sampling .99Objectives and Requirements . 99Significant Industrial User Monitoring Program. 100Biosolids Monitoring Program. 100Toxicity Testing Program . 100StormWater Program . 100B. Sampling Procedures and Techniques . 100Wastewater Sample Collection Techniques . 101EPA Sample Identification Methods . 106Wastewater Sample Preservation and Holding Time. 106Transfer of Custody and Shipment of Samples . 107Quality Control . 108Quality Assurance Project Plan . 112Data Handling and Reporting . 113C. References. 113D. Permittee Sampling Inspection Checklist . 115List of TablesTable 5-1. Compositing Methods . 102Table 5-2. Quality Control Procedures for Field Analysis and Equipment . 110Associated AppendicesM.N.Example Chain-of-Custody FormUpdated Fact Sheet: Department of Transportation Hazardous Materials TrainingRelated WebsitesAgency-wide Quality System Documents: stemdocumentsChapter 5 – Page 98

U.S. EPA Interim Revised NPDES Inspection Manual 2017A.EVALUATION OF PERMITTEE SAMPLINGPROGRAM AND COMPLIANCE SAMPLINGWastewater sampling/analysis is an integral part of the National Pollutant DischargeElimination System (NPDES) Compliance Monitoring Program. NPDES permits contain specificand legally enforceable effluent limitations and monitoring requirements.OBJECTIVES AND REQUIREMENTSWhen evaluating the permittee sampling program, the inspector should: Verify that the permittee's sampling program complies with the permit. Verify that the permittee's sampling program complies with:– Title 40 of the Code of Federal Regulations (CFR), sections 136.1 to 136.6 andAppendices A, B, and C (Guidelines for Establishing Test Procedures for the Analysisof Pollutants) for wastewater samples; and 40 CFR Part 503.Document potential violations to support enforcement action.In addition, specific objectives of the sampling conducted by inspectors include the following: Verify compliance with effluent limitations.Verify accuracy of reports and program self-monitoring.Support enforcement action.Support permit development reissuance and/or revision.Determine the quantity and quality of effluent.Sampling, analysis, preservation technique, sample holding time, and sample containerrequirements are provided under 40 CFR Part 136 as authorized by section 304(h) of the CleanWater Act (CWA). Chapter 7 contains more information on required analytical procedures"Laboratory Analyses Techniques Evaluation." See the checklist for use in evaluating thepermittee's sampling program at the end of this chapter.For all NPDES permittees the inspector should perform a review of sampling procedures andquality control measures the facility uses to ensure the integrity of sample data.To evaluate sampling procedures, assess the following eight areas: Sample site locationsSample collection techniquesField measurementsSample labeling (including locations) and documentationSample preservation and holding timeTransfer of custody and shipment of samplesQuality controlChapter 5 – Page 99

U.S. EPA Interim Revised NPDES Inspection Manual 2017 Data handling and reportingSIGNIFICANT INDUSTRIAL USER MONITORING PROGRAMIt is the responsibility of the permitted Publicly Owned Treatment Works (POTW) with apretreatment program to oversee sampling procedures of industrial users and to conductcompliance monitoring of its own. Therefore, during a Pretreatment Compliance Inspection(PCI) or audit, the inspector may also need to evaluate POTW sampling procedures forsignificant industrial users who discharge to the POTW in addition to evaluating the samplingprocedures of any permitted POTW. According to the General Pretreatment Regulations, 40CFR 403.12(o), industrial users and POTWs subject to 40 CFR 403.12 reporting requirementsmust maintain the following monitoring records: Date, exact place, method and time of sampling, and name of samplerDate of analysisName of analystAnalytical techniques/methods usedAnalytical resultsDuring a PCI or an audit, the inspector evaluates the POTW industrial user monitoring programwith respect to the criteria specified in the POTW pretreatment program. Elements of thesampling scheme will include the eight areas addressed above and any other areas specificallyaddressed in the pretreatment program. Chapter 9 discusses the focus of this evaluation ingreater detail.BIOSOLIDS MONITORING PROGRAMChapter 10 discusses evaluation of a permittee’s biosolids monitoring program. Lists ofapproved biosolids analytical methods, sample containers, preservation techniques, andholding times for biosolids samples can be found on EPA’s website ation-biosolids-managers#analytical.TOXICITY TESTING PROGRAMChapter 8 discusses evaluation of a permittee’s Whole Effluent Toxicity testing program. Inaddition, for methods manuals for Whole Effluent Toxicity testing go oxicity-methods.STORMWATER PROGRAMChapter 11 provides considerations for performing stormwater monitoring.B.SAMPLING PROCEDURES AND TECHNIQUESWhether an inspector is evaluating a permittee's sampling program or conducting compliancesampling on the permittee's effluent, that inspector must be familiar with the procedures andtechniques necessary for accurate sampling of wastewaters. The following discussion detailsChapter 5 – Page 100

U.S. EPA Interim Revised NPDES Inspection Manual 2017the procedures for sample collection, preservation, sample transfer including chain-of-custody,quality control, and data handling.WASTEWATER SAMPLE COLLECTION TECHNIQUESSample collection is an important part of the compliance monitoring program. Without propersample collection procedures, the results of such monitoring programs are neither useful norvalid, even with the most precise and accurate analytical measurements.Selection of Representative Sampling SitesNormally, samples should be collected at the location specified in the permit. In someinstances, the sampling location specified in the permit may not be adequate for the collectionof a representative sample. In that case, the inspector should determine the mostrepresentative sampling point available and collect a sample at that location as well as thelocation specified by the permit (or chosen by the permittee). If the facility disagrees, thereason for the conflict must be documented for later resolution by the permitting authority.Sample TypesTwo types of sample techniques are used: grab and composite. For many monitoringprocedures, the regulations at 40 CFR Part 136 do not specify sampling type. For theseprocedures, the NPDES permit writer determines the appropriate sample type based on thedata objective, and/or the required analytical method and specifies the sampling technique inthe NPDES permit.Grab Samples. Grab samples are individual samples collected at a specific time not exceeding15 minutes and are representative of the conditions at the time the sample is collected. Thesample volume depends on the type and number of analyses to be performed. The collection ofa grab sample is appropriate when a sample is needed to: Represent an effluent that does not discharge on a continuous basis.Provide information about instantaneous concentrations of pollutants at a specific time.Allow collection of a variable sample volume.Corroborate composite samples.Monitor parameters not amenable to compositing (e.g., pH, temperature, dissolvedoxygen, chlorine, purgeable organics, oil and grease, coliform bacteria, and othersspecified by the NPDES permit, which may include phenols, sulfites, and hexavalentchromium).Composite Samples. Composite samples are samples collected over time, either by continuoussampling or by mixing discrete samples. Composite samples represent the averagecharacteristics of the wastestream during the compositing period. Composite samples arecollected when: Average pollutant concentration during the compositing period is desired.Mass per unit time loadings are calculated.Chapter 5 – Page 101

U.S. EPA Interim Revised NPDES Inspection Manual 2017 Wastewater characteristics are highly variable.The four primary methods of composite sample collection are time compositing, flowproportion compositing, sequential compositing, and continuous compositing. Table 5-1 liststhe advantages and disadvantages of these methods. The permit may specify which type ofcomposite sample to use. Composite samples are collected either manually by combiningmultiple grab samples or by using automatic sampling equipment. Inspectors should considervariability in wastestream flow rate, parameter concentrations and the approved EPA methodswhen choosing compositing methods, sampling equipment (tubing and containers), and qualityassurance procedures. The compositing methods are as follows: Time Composite Sample: This method requires discrete sample aliquots collected in onecontainer at constant time intervals. This method is appropriate when the flow of thesampled stream is constant (flow rate does not vary more than 10 percent of theaverage flow rate) or when flow monitoring equipment is not available.Table 5-1. Compositing MethodsMethodAdvantagesTime CompositeConstant sampleMinimal manual effort;volume, constant timerequires no flowinterval betweenmeasurement.samples.Flow-Proportional CompositeConstant sampleMinimal manual effort.volume, time intervalbetween samplesproportional to streamflow.Constant time intervalMinimal instrumentation.between samples,sample volumeproportional to totalstream flow at time ofsampling.Constant time intervalbetween samples,sample volumeproportional to totalstream flow since lastsample.Chapter 5 – Page 102Minimal instrumentation.DisadvantagesCommentsMay lack representativeness forhighly variable flows.Widely used in bothautomatic and manualsampling.Requires accurate flowmeasurement readingequipment; manual compositingfrom flowchart.Widely used inautomatic as well asmanual sampling.Manual compositing fromflowchart in absence of priorinformation on the ratio ofminimum to maximum flow;chance of collecting too small ortoo large individual discretesamples for a given compositevolume.Manual compositing from flowchart in absence of priorinformation on the ratio ofminimum to maximum flow;chance of collecting too small ortoo large individual discretesamples for a given compositevolume.Used in automaticsamplers and widelyused as manualmethod.Not widely used inautomatic samplersbut may be donemanually.

U.S. EPA Interim Revised NPDES Inspection Manual 2017Table 5-1. Compositing MethodsMethodSequential CompositeSeries of short periodcomposites, constanttime intervals betweensamples.Series of short periodcomposites, aliquotstaken at constantdischarge increments.Continuous CompositeConstant samplevolume.Sample volumeproportional to streamflow.AdvantagesDisadvantagesUseful if fluctuations occurand the time history isdesired.Requires manual compositing ofaliquots based on flow.Useful if fluctuations occurand the time history isdesired.Requires flow totalizer; requiresmanual compositing of aliquotsbased on flow.Minimal manual effort,requires no flowmeasurement highly variableflows.Minimal manual effort, mostrepresentative especially forhighly variable samplevolume, variable pumpingcapacity and power.Requires large sample capacity;may lack representativeness forhighly variable flows.CommentsCommonly used;however, manualcompositing is laborintensive.Manual compositing islabor intensive.Practical but notwidely used.Requires accurate flowNot widely used.measurement equipment, largesample volume, variable pumpingcapacity, and power. Flow-Proportional Composite Sample—in one method, a constant sample volume iscollected at varying time intervals proportional to stream flow (e.g., 200 milliliterssample collected for every 5,000 gallons of flow). In the other method (which has twovariations, see Table 5-1), the sample is collected by increasing the volume of eachaliquot as the flow increases, while maintaining a constant time interval between thealiquots. Sequential Composite Sample—this method requires discrete samples collected inindividual containers at constant time intervals or discharge increments; for example,samples collected every 15 minutes, composited into separate containers each hour.The discrete samples can then be manually flow-proportioned to form the compositesample. Alternatively, a constant sample volume is collected at constant dischargevolume increments measured with a flow totalizer. Continuous Composite Sample—collect this sample continuously from the wastestream.The sample may be constant volume, or the volume may vary in proportion to the flowrate of the wastestream.Influent Sample Collection. Document and take influent samples at points of high turbulenceflow to ensure good mixing. In some instances, the most desirable location may not beaccessible. Ensure sampling points are located prior to any internal facility return lines, andsampling equipment should be placed so that it does not interfere with flow measuring devices.The preferred sampling points for raw wastewater are at the most downstream location fromthe collection lines, but prior to preliminary treatment:Chapter 5 – Page 103

U.S. EPA Interim Revised NPDES Inspection Manual 2017 Waste flowing from the last process in a manufacturing operation, for an industrial user.Pump wet well (if turbulent).Upstream collection lines, tank, or distribution box following pumping from the wet wellor sump.Flume throat.Aerated grit chamber.Upstream siphon following the comminutor (in absence of grit chamber).If it is not possible to sample at a preferred point, choose an alternative location and documentthe basis for choosing that location.Effluent Sample Collection. Collect effluent samples at the location specified in the NPDESpermit. Occasionally, municipal plant permits may specify sampling prior to chlorination. Forthese plants, monitor all parameters at the upstream location except fecal coliforms, pH, andtotal residual chlorine. Collect wastewater for use in bioassays at the location specified in thefacility's NPDES permit.Collect samples either manually (grab or composite) or with automatic samplers (continuous orcomposite). The following general guidelines apply when taking samples: Take samples at a location specified in the NPDES permit and/or at a location selectedto yield a representative sample. Use the sampling method (grab, composite, continuous) specified in the permit. Someparameters that must be collected as an individual grab sample are dissolved oxygen,total residual chlorine, oil and grease, coliform bacteria, purgeable organics, sulfides,cyanide, and total phenols. Avoid collecting large nonhomogeneous particles and objects. Collect the sample facing upstream to avoid contamination. Do not rinse sample container with sample when collecting oil and grease andmicrobiological samples, but fill the container directly to within 2.5 to 5 cm from thetop. Fill the container completely if the sample is to be analyzed for purgeable organics,oxygen, ammonia, hydrogen sulfide, free chlorine, pH, hardness, sulfite, ammonium,ferrous iron, acidity, or alkalinity. Collect sufficient volume to allow for quality assurance testing. (see EPA’s websitehttps://www.epa.gov/cwa-methods for a listing of all approved sampling methods. Eachsampling method will indicate the required sampling equipment, sampling containersand sampling volume, but additional volumes may be necessary for quality assurancetesting.)Chapter 5 – Page 104

U.S. EPA Interim Revised NPDES Inspection Manual 2017The following general guidelines apply when using automatic samplers: Collect samples where the wastewater is well mixed. Collect the sample near the centerof the flow channel at 0.4 to 0.6 depth (mid-depth). Obtain a sufficient volume of sample to perform all required analyses plus anyadditional amount for quality control. Individual portions of a composite sample shouldbe at least 100 milliliters to minimize sampler solids bias. For automatic samplers that use a peristaltic pump, obtain adequate flow rates in thesampler tubing to effectively transport the suspended solids. To avoid solids bias, thevelocity of the wastewater in sample tubing should be at least 2 feet per second (fps)and the tubing diameter should be at least 0.25 inch. Time of sample collection begins when the last aliquot is dispensed into the compositesample container.Sample VolumeThe volume of sample collected depends on the type and number of analyses needed, asreflected in the parameters to be measured. Obtain the volume of the sample sufficient for allthe required analyses plus an additional amount to provide for any split samples or repeatanalyses. EPA approved sampling methods provide a guide to sample volumes required fordetermining the constituents in wastewater (available at https://www.epa.gov/cwa-methods).Consult the laboratory receiving the sample for any specific volume required. EPA's Methods forChemical Analysis of Water and Wastes (EPA, 1979a) and Handbook for Sampling and SamplePreservation of Water and Wastewater (EPA, 1982), and the current EPA-approved edition ofStandard Methods for the Examination of Water and Wastewater (American Public HealthAssociation (APHA), American Water Works Association (AWWA), and Water EnvironmentFederation (WEF), 2013) contain specific recommended minimum sample volumes for differentpollutant parameters.Sample ContainersThe regulations at 40 CFR Part 136 describe required sample containers, sample preservation,and sample holding time. EPA approved sampling methods indicate appropriate samplecontainers for each analysis It is essential that the sample containers be made of chemicallyresistant material unaffected by the concentrations of the pollutants measured. In addition,sample containers must have a closure that will protect the sample from contamination. Collectwastewater samples for chemical analysis in plastic (polyethylene) containers. Exceptions tothis general rule are oil and grease samples, pesticides, phenols, polychlorinated biphenyls(PCBs), and other organic

Verify that the permittee's sampling program complies with the permit. Verify that the permittee' s sampling program complies with: – Title 40 of the Code of Federal Regulations (CFR),sections 136.1 to 136.6 and Appendices A, B, and C (Gui