ASTM D6538-12(2019)
(Guide)Standard Guide for Sampling Wastewater With Automatic Samplers
Standard Guide for Sampling Wastewater With Automatic Samplers
SIGNIFICANCE AND USE
4.1 This guide provides persons responsible for designing and implementing wastewater sampling programs with a summary of the types of automatic wastewater samplers, discusses the advantages and disadvantages of the different types of samplers, and addresses recommended procedures for their use. The field settings are primarily, but not limited to, open channel flows in enclosed (e.g., sewer) systems or open (e.g., streams or open ditches, and sampling pressure lines) systems.
SCOPE
1.1 This guide covers the selection and use of automatic wastewater samplers, including procedures for their use in obtaining representative samples. Automatic wastewater samplers are intended for the unattended collection of samples that are representative of the parameters of interest in the wastewater body. While this guide primarily addresses the sampling of wastewater, the same automatic samplers may be used to sample process streams and natural water bodies.
1.2 The guide does not address general guidelines for planning waste sampling activities (see Guide D4687), development of data quality objectives (see Practice D5792), the design of monitoring systems and determination of the number of samples to collect (see Guide D6311), operational details of any specific type of sampler, in-situ measurement of parameters of interest, data assessment and statistical interpretation of resultant data (see Guide D6233), or sampling and field quality assurance (see Guide D5612). It also does not address sampling groundwater.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3.1 Exception—The inch-pound units given in parentheses are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6538 − 12 (Reapproved 2019)
Standard Guide for
Sampling Wastewater With Automatic Samplers
This standard is issued under the fixed designation D6538; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This guide covers the selection and use of automatic
D4687 Guide for General Planning of Waste Sampling
wastewater samplers, including procedures for their use in
D5088 Practice for Decontamination of Field Equipment
obtaining representative samples. Automatic wastewater sam-
Used at Waste Sites
plers are intended for the unattended collection of samples that
D5612 Guide for Quality Planning and Field Implementa-
are representative of the parameters of interest in the waste-
tion of a Water Quality Measurement Program
water body. While this guide primarily addresses the sampling
D5681 Terminology for Waste and Waste Management
of wastewater, the same automatic samplers may be used to
D5792 Practice for Generation of Environmental Data Re-
sample process streams and natural water bodies.
lated to Waste Management Activities: Development of
1.2 The guide does not address general guidelines for
Data Quality Objectives
planning waste sampling activities (see Guide D4687), devel-
D6233 Guide for DataAssessment for Environmental Waste
opment of data quality objectives (see Practice D5792), the 3
Management Activities (Withdrawn 2016)
design of monitoring systems and determination of the number
D6311 Guide for Generation of Environmental Data Related
of samples to collect (see Guide D6311), operational details of
to Waste ManagementActivities: Selection and Optimiza-
any specific type of sampler, in-situ measurement of param-
tion of Sampling Design
eters of interest, data assessment and statistical interpretation
of resultant data (see Guide D6233), or sampling and field
3. Terminology
quality assurance (see Guide D5612). It also does not address
3.1 Definitions—For definitions of terms used in this guide,
sampling groundwater.
refer to Terminology D5681.
1.3 The values stated in SI units are to be regarded as
4. Significance and Use
standard. No other units of measurement are included in this
standard. 4.1 This guide provides persons responsible for designing
and implementing wastewater sampling programs with a sum-
1.3.1 Exception—Theinch-poundunitsgiveninparentheses
mary of the types of automatic wastewater samplers, discusses
are for information only.
the advantages and disadvantages of the different types of
1.4 This standard does not purport to address all of the
samplers, and addresses recommended procedures for their
safety concerns, if any, associated with its use. It is the
use. The field settings are primarily, but not limited to, open
responsibility of the user of this standard to establish appro-
channel flows in enclosed (e.g., sewer) systems or open (e.g.,
priate safety, health, and environmental practices and deter-
streams or open ditches, and sampling pressure lines) systems.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
5. Automatic Versus Manual Sampling (2, 3)
dance with internationally recognized principles on standard-
5.1 The advantages and disadvantages of manual and auto-
ization established in the Decision on Principles for the
matic sampling are summarized in Table 1. The decision as to
Development of International Standards, Guides and Recom-
whether to use manual or automatic sampling involves many
mendations issued by the World Trade Organization Technical
considerations in addition to equipment costs. In general,
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
This guide is under the jurisdiction of ASTM Committee D34 on Waste Standards volume information, refer to the standard’s Document Summary page on
Management and is the direct responsibility of Subcommittee D34.01.03 on the ASTM website.
Sampling Equipment. The last approved version of this historical standard is referenced on
Current edition approved Sept. 1, 2019. Published September 2019. Originally www.astm.org.
approved in 2000. Last previous edition approved in 2012 as D6538 – 12. DOI: The boldface numbers given in parentheses refer to a list of references at the
10.1520/D6538-12R19. end of the standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6538 − 12 (2019)
TABLE 1 Advantages and Disadvantages of Manual versus
specified by a permit which may include phenols, sulfites, and
Automatic Sampling of Wastewater (1)
hexavalent chromium).
Type Advantages Disadvantages
6.1.6 Characterize a waste stream in detail where rapid
Manual Low capital cost Increased variability due to
fluctuations of parameters occur (sequential grabs).
sample handling
Personnel can compensate for Inconsistency in collection
6.2 Composite Samples—Composite samples are collected
various situations
Personnel can document High cost of labor assuming over time, either by continuous sampling or by mixing discrete
unusual conditions composite or multiple grab
samples, and represent the average characteristics of the waste
samples are collected
stream during the compositing period. Composite samples are
Low maintenance Repetitious and monotonous
task for personnel
collected when stipulated in a permit, when average pollutant
Extra samples can be collected
concentration during the compositing period is to be
in a short time if necessary
determined, and when wastewater characteristics are highly
Automatic Consistent samples Considerable maintenance for
variable. There are four types of composite samples.
batteries and cleaning;
6.2.1 Time-Composite Samples—This method requires dis-
susceptible to plugging by
solids
crete sample aliquots be collected in one container at constant
Decreased variability caused by Restricted in size to the general
time intervals. The method is appropriate when the flow of the
sample handling specifications
streamisconstant(flowratedoesnotvarymorethan 610 %of
Minimal labor requirement for Greater potential for sample
sampling contamination
the average flow rate (4)) or when flow monitoring equipment
Capable of collecting multiple May be subject to damage by
is not available. The EPA allows time-proportional sampling
grab and multiple aliquot vandals
composite samples and requires samples be collected every 15 min, on average,
High capital cost
over a 24-h period.
6.2.2 Flow-Proportional Composite Samples—There are
two methods used for this type of sample (4). The most
commonly used method with automatic samplers collects a
constant sample volume at varying time intervals proportional
manual sampling is indicated when infrequent samples are
to stream flow based on input from a flow monitor (for
required from a site, when biological or sediment samples, or
example, a 200-mL aliquot is collected for every 5000 L of
both, are also required, when investigating special incidents,
where sites will not allow the use of automatic devices, for flow). In the other flow-proportional compositing method, the
sample is collected by varying the volume of each aliquot as
most bacteriological sampling, where concentrations remain
relatively constant, etc. The use of automatic samplers is the flow varies, while maintaining a constant time interval
indicated where frequent sampling is required at a given site, between the aliquots.
where long-term compositing is desired, where simultaneous
6.2.3 Sequential Composite Samples—A sequential com-
sampling at many sites is necessary, etc.Automatic sampling is
posite sample is composed of a series of short-period
often the method of choice for storm-generated discharge
composites, each of which is held in an individual container,
studies, for longer outfall monitoring, for treatment plant
for example, four sample aliquots are composited (one every
efficiency studies, where 24-h composite samples are required,
15 min) to form hourly composites (4). The 24-h sequential
etc. The user should review 7.1.23 before selecting manual or
composite is then manually made by compositing the indi-
automatic sampling.
vidual 1-h composite sample.
6.2.4 Continuous Composite Samples—This method re-
6. Types of Samples Collected by Automatic Samplers
quires that the sample be collected continuously at a constant
6.1 Grab Samples—As defined under the U.S. Environmen-
rate or proportional to flow (4). This method is seldom used
tal Protection Agency’s (EPA) National Pollutant Discharge
with automatic samplers.
Elimination Program, grab samples are individual samples
collected over a period of time not exceeding 15 min and are
7. Attributes of Automatic Samplers
representative of conditions at the time of sampling (4). Grab
7.1 The EPA (6) developed a list of attributes of the ideal
samples are sometimes also called individual or discrete
automatic sampler for their use and EPA Region 4 (7) and
samples (5). Sequential grab samples are a series of grab
others (1) have noted other important attributes. These attri-
samples collected at constant increments of either time or flow
butes and requirements may be specific to EPA’s use and were
and provide a history of variation. Grab samples are appropri-
primarily directed at suction lift type automatic samplers. Not
ate when samples are needed to:
all these sampler characteristics will be important to all users,
6.1.1 Characterize an effluent that is not continuous.
but their consideration may guide persons selecting automatic
6.1.2 Provide information about instantaneous concentra-
samplers. The desirable features of automatic samplers listed
tions of pollutants.
below have been summarized and combined from the refer-
6.1.3 Allow collection of samples of varied volume.
enced documents.
6.1.4 Corroborate composite samples.
6.1.5 Monitor parameters not amenable to compositing (for 7.1.1 Capable of AC/DC operation with adequate dry bat-
example, pH, temperature, dissolved oxygen, chlorine, purge- tery energy storage for 120-h operation at 1-h sampling
able organics (unless a specialized sampler is used), and others intervals.
D6538 − 12 (2019)
7.1.2 Suitable for suspension in a standard manhole yet still 7.1.22.2 Ability to calibrate the sample pump volume, and
accessible for inspection and sample removal.Asecure harness calibrate any attached parameter modules.
or mounting device if the sampler is placed in a sewer. 7.1.23 Other Factors—Other factors (1) that should be
considered in selecting an automatic sampler are the:
7.1.3 Total weight, including batteries, less than 18 kg.
Compact and portable enough for one-person installation. 7.1.23.1 Expected variation in water or wastewater compo-
sition with time,
7.1.4 Sample collection interval adjustable from 10 min to
7.1.23.2 Variation of flow rate with time,
4h.
7.1.23.3 Specific gravity of the liquid,
7.1.5 Capable of collecting a single 9.5-L (2.5-gal) sample
and/or collecting 500-mL (0.13-gal) discrete samples in a 7.1.23.4 Concentration and density of suspended solids of
minimum of 24 containers.The individual sample aliquot must interest,
be at least 100 mL.
7.1.23.5 Presence of floating materials,
7.1.6 Capable of multiplexing repeated aliquots into dis- 7.1.23.6 Characteristicsofthesitewherethesamplerwillbe
crete bottles.
placed (e.g., space needed for the sampler placement),
7.1.7 One intake hose with a minimum inner diameter of
7.1.23.7 Range of intended use (a permanent site or travel-
0.64 cm (0.25 in.) and a weighted, streamlined intake screen
ing sampler),
which will prevent accumulation of solids.
7.1.23.8 Skill level required for installation and operation of
7.1.8 Intake hose liquid velocity adjustable from 0.6 to the sampler, and
3 m⁄s (2.0 to 10 ft/s) with dial setting.
7.1.23.9 The level of accuracy desired.
7.1.9 Minimum lift capacity of 6.1 m (20 ft).
8. Types of Automatic Samplers (1-3)
7.1.10 Explosion-proof construction.
7.1.11 Watertight exterior case to protect components in the 8.1 There are three main types of automatic samplers:
event of rain or submersion. suction lift, pressure or forced flow, and mechanical. Each has
its advantages and limitations and all types are available in
7.1.12 Exterior case capable of being locked, including lugs
models designed to preserve samples via cooling (iced or
for attaching steel cable to prevent tampering and to provide
refrigerated).While all automatic samplers can collect samples
security.
through time, some samplers are designed to be triggered by
7.1.13 An integral sample container compartment capable
inputs from online devices measuring flow, pH, temperature,
of maintaining samples at 4 to 6 °C for a period of 24 h at
conductance, etc., and collect samples under specific condi-
ambient temperatures up to 38 °C.
tions (for example, pH > 9.0).
7.1.14 Capable of operating in a temperature range from
–10 to 40 °C with the exception of the intake hose.
8.2 Suction Lift—Suction lift devices can be further subdi-
7.1.15 A purge cycle to flush the sample intake tubing
vided into peristaltic and vacuum-type samplers. Peristaltic
before and after each collection interval, and a mechanism to
pump devices are the most commonly used type in the United
sense and clear a plugged sample line and then collect the
States and use a rotating head to pinch a flexible hose, creating
complete sample. Samplers may be programmed to perform an
a vacuum to transport the sample to the container. Vacuum
air purge before and after sampling, and a liquid rinse before
devices (8) are more popular in Europe and use a vacuum
and after a sample is drawn.
pump to transport the sample to the sample container. Suction
7.1.16 Capable of collecting flow-proportional and time- lift samplers are portable, versatile due to their light weight,
composite samples.
and can purge the transport line between samples. Their main
7.1.17 Materials of construction that contact the sample limitationisthattheirliftcapacitywhichisclaimedtorangeup
must not compromise the integrity of the sample for the to 9 m but may be significantly less. Also, since suction lift
intended use. devices use a vacuum to transport samples, the
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