ASTM D6538-00
(Guide)Standard Guide for Sampling Wastewater With Automatic Samplers
Standard Guide for Sampling Wastewater With Automatic Samplers
SCOPE
1.1 This guide covers the selection and use of automatic wastewater samplers including procedure 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 wastewateer 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 systemsand determination of the number of samples to collect (see Practice 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 GuideD5612). It also does not address sampling groundwater.
1.3 The values stated in SI units are to be regarded as the standard. 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:D6538–00
Standard Guide for
Sampling Wastewater With Automatic Samplers
This standard is issued under the fixed designation D 6538; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 4840 Guide for Sampling Chain-of-Custody Procedures
D 5088 Practice for Decontamination of Field Equipment
1.1 This guide covers the selection and use of automatic
Used at Nonradioactive Waste Sites
wastewater samplers including procedures for their use in
D 5283 Practice for Generation of Environmental Data
obtaining representative samples. Automatic wastewater sam-
Related to Waste Management Activities Quality Assur-
plers are intended for the unattended collection of samples that
ance and Quality Control Planning and Implementation
are representative of the parameters of interest in the waste-
D 5612 Guide for Quality Planning and Field Implementa-
water body. While this guide primarily addresses the sampling
tion of a Water Quality Measurement Program
of wastewater, the same automatic samplers may be used to
D 5792 Practice for Generation of Environmental Data
sample process streams and natural water bodies.
Related to Waste ManagementActivities: Development of
1.2 The guide does not address general guidelines for
Data Quality Objectives
planning waste sampling activities (see Guide D 4687), devel-
D 5851 Guide for Planning and Implementing a Water
opment of data quality objectives (see Practice D 5792), the
Monitoring Program
design of monitoring systems and determination of the number
D 5956 Guide for Sampling Strategies for Heterogeneous
of samples to collect (see Practice D 6311), operational details
Wastes
of any specific type of sampler, in-situ measurement of
D 6233 Guide for Data Assessment for Environmental
parameters of interest, data assessment and statistical interpre-
Waste Management Activities
tation of resultant data (see Guide D 6233), or sampling and
D 6311 Practice for Generation of Environmental Data
field quality assurance (see Guide D 5612). It also does not
Related to Waste Management Activities: Optimizing
address sampling groundwater.
Sampling Design
1.3 The values stated in SI units are to be regarded as the
E 856 Definitions of Terms and Abbreviateions Relating to
standard. The inch-pound units given in parentheses are for
Physical and Chemical Characteristics of Refuse Derived
information only.
Fuel
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 composite sample, n—a combination of two or more
priate safety and health practices and determine the applica-
samples. (D 1129)
bility of regulatory limitations prior to use.
3.2 representative sample, n—a sample collected such that
2. Referenced Documents it reflects one or more characteristics of interest (as defined by
the project objectives) of a population from which it was
2.1 ASTM Standards:
collected. (D 5956)
D 1129 Terminology Relating to Water
3.3 sample, n—a portion of material taken from a larger
D 3694 Practices for Preparation of Sample Containers and
quantity for the purpose of estimating properties or composi-
for Preservation of Organic Constituents
tion of the larger quantity. (E 856)
D 3856 Guide for Good Laboratory Practices in Laborato-
ries Engaged in Sampling and Analysis of Water
4. Significance and Use
D 4687 Guide for General Planning of Waste Sampling
4.1 This guide provides persons responsible for designing
and implementing wastewater sampling programs with a sum-
This guide is under the jurisdiction of ASTM Committee D34 on Waste mary of the types of automatic wastewater samplers, discusses
Management and is the direct responsibility of Subcommittee D34.01.01 on
the advantages and disadvantages of the different types of
Planning for Sampling.
samplers and addresses recommended procedures for their use.
Current edition approved May 10, 2000. Published July 2000.
Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 11.02.
4 5
Annual Book of ASTM Standards, Vol 11.04. Annual Book of ASTM Standards, Vol 04.09.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D6538
TABLE 1 Advantages and Disadvantages of Manual versus
6.1.2 Provide information about instantaneous concentra-
Automatic Sampling of Wastewater (3)
tions of pollutants,
Type Advantages Disadvantages
6.1.3 Allow collection of samples of varied volume,
Manual Low capital cost Increased variability due to
6.1.4 Corroborate composite samples,
sample handling
Personnel can compensate for Inconsistency in collection 6.1.5 Monitor parameters not amenable to compositing (for
various situations
example, pH, temperature, dissolved oxygen, chlorine, purge-
Personnel can document High cost of labor assuming
able organics (unless a specialized sampler is used), oil and
unusual conditions composite or multiple grab
samples are collected
grease and others specified by a permit which may include
No maintenance Repetitious and monotonous
phenols, sulfites and hexavalent chromium).
task for personnel
Extra samples can be collected 6.1.6 Characterize a waste stream in detail where rapid
in a short time if necessary
fluctuations of parameters occur (sequential grabs).
6.2 Composite Samples—Composite samples are collected
Automatic Consistent samples Considerable maintenance for
batteries and cleaning;
over time, either by continuous sampling or by mixing discrete
susceptible to plugging by
samples, and represent the average characteristics of the waste
solids
stream during the compositing period. Composite samples are
Decreased variability caused by Restricted in size to the general
sample handling specifications
collected when stipulated in a permit, when average pollutant
Minimal labor requirement for Greater potential for sample
concentration during the compositing period is to be deter-
sampling contamination
mined, and when wastewater characteristics are highly vari-
Capable of collecting multiple May be subject to damage by
grab and multiple aliquot vandals
able. There are four types of composite samples.
composite samples
6.2.1 Time Composite Samples—This method requires dis-
High capital cost
crete sample aliquots be collected in one container at constant
time intervals. The method is appropriate when the flow of the
streamisconstant(flowratedoesnotvarymorethan 610 %of
5. Automatic Versus Manual Sampling (1, 2)
the average flow rate (4)) or when flow monitoring equipment
5.1 The advantages and disadvantages of manual and auto-
is not available. The EPA allows time-proportional sampling
matic sampling are summarized in Table 1. The decision as to
and requires samples be collected every 15-min, on average,
whether to use manual or automatic sampling involves many
over a 24-h period.
considerations in addition to equipment costs. In general,
6.2.2 Flow-Proportional Composite Samples—There are
manual sampling is indicated when infrequent samples are
two methods used for this type of sample (4). The most
required from a site, when biological or sediment samples, or
commonly used method with automatic samplers collects a
both, are also required, when investigating special incidents,
constant sample volume at varying time intervals proportional
where sites will not allow the use of automatic devices, for
to stream flow based on input from a flow monitor (for
most bacteriological sampling, where concentrations remain
example, a 200-mL aliquot is collected for every 5000 L of
relatively constant, etc. The use of automatic samplers is
flow). In the other flow-proportional compositing method, the
indicated where frequent sampling is required at a given site,
sample is collected by varying the volume of each aliquot as
where long-term compositing is desired, where simultaneous
the flow varies, while maintaining a constant time interval
sampling at many sites is necessary, etc.Automatic sampling is
between the aliquots.
often the method of choice for storm-generated discharge
6.2.3 Sequential Composite Samples—A sequential com-
studies, for longer outfall monitoring, for treatment plant
posite sample is composed of a series of short-period compos-
efficiency studies, where 24-h composite samples are required,
ites, each of which is held in an individual container, for
etc. The user should review 7.1.22 before selecting manual or
example, four sample aliquots are composited (one every 15
automatic sampling.
min) to form hourly composites (4). The 24-h sequential
6. Types of Samples Collected by Automatic Samplers
composite is then manually made by compositing the indi-
6.1 GrabSamples—As defined under the U.S. Environmen- vidual 1-h composite sample.
tal Protection Agency’s (EPA) National Pollutant Discharge
6.2.4 Continuous Composite Samples—This method re-
Elimination Program, grab samples are individual samples
quires that the sample be collected continuously at a constant
collected over a period of time not exceeding 15 min and are
rate or proportional to flow (4). This method is seldom used
representative of conditions at the time of sampling (4). Grab
with automatic samplers.
samples are sometimes also called individual or discrete
samples (5). Sequential grab samples are a series of grab
7. Attributes of Automatic Samplers
samples collected at constant increments of either time or flow
7.1 The EPA (6) developed a list of attributes of the ideal
and provide a history of variation. Grab samples are appropri-
automatic sampler for their use and EPA Region 4 (7) and
ate when samples are needed to:
others (3) have noted other important attributes. These at-
6.1.1 Characterize an effluent that is not continuous,
tributes and requirements may be specific to EPA’s use and
were primarily directed at suction lift type automatic samplers.
Not all these sampler characteristics will be important to all
The boldface numbers given in parentheses refer to a list of references at the
end of the standard. users but their consideration may guide persons selecting
D6538
automatic samplers. The desirable features of automatic sam- 7.1.22 Other Factors—Other factors (3) that should be
plers listed below have been summarized and combined from considered in selecting an automatic sampler are the:
the referenced documents. 7.1.22.1 Expected variation in water or wastewater compo-
7.1.1 Capable of AC/DC operation with adequate dry bat- sition with time,
7.1.22.2 Variation of flow rate with time,
tery energy storage for 120-h operation at 1-h sampling
intervals. 7.1.22.3 Specific gravity of the liquid
7.1.22.4 Concentration and density of suspended solids of
7.1.2 Suitable for suspension in a standard manhole yet still
interest,
accessible for inspection and sample removal.Asecure harness
7.1.22.5 Presence of floating materials,
or mounting device if the sampler is placed in a sewer.
7.1.22.6 Characteristicsofthesitewherethesamplerwillbe
7.1.3 Total weight, including batteries, less than 18 kg.
placed,
Compact and portable enough for one-person installation.
7.1.22.7 Range of intended use (a permanent site or travel-
7.1.4 Sample collection interval adjustable from 10 min to 4
ing sampler),
h.
7.1.22.8 Skill level required for installation and operation of
7.1.5 Capable of collecting a single 9.5-L (2.5-gal) sample
the sampler, and
and/or collecting 500-mL (0.13-gal) discrete samples in a
7.1.22.9 The level of accuracy desired.
minimum of 24 containers.The individual sample aliquot must
be at least 100 mL.
8. Types of Automatic Samplers (1,2,3)
7.1.6 Capable of multiplexing repeated aliquots into dis-
8.1 There are three main types of automatic samplers,
crete bottles.
suction lift, pressure or forced flow, and mechanical. Each has
7.1.7 One intake hose with a minimum inner diameter of
its advantages and limitations and all types are available in
0.64 cm (0.25 in) and a weighted, streamlined intake screen
models designed to preserve samples via cooling (iced or
which will prevent accumulation of solids.
refrigerated).While all automatic samplers can collect samples
7.1.8 Intake hose liquid velocity adjustable from 0.6 to 3
through time, some samplers are designed to be triggered by
m/s (2.0 to 10 ft/s) with dial setting.
inputs from online devices measuring flow, pH, temperature,
7.1.9 Minimum lift capacity of 6.1 m (20 ft).
conductance, etc., and collect samples under specific condi-
7.1.10 Explosion proof construction.
tions (for example, pH >9.0).
7.1.11 Watertight exterior case to protect components in the
8.2 Suction Lift—Suction lift devices can be further subdi-
event of rain or submersion.
vided into peristaltic and vacuum type samplers. Peristaltic
7.1.12 Exterior case capable of being locked, including lugs
pump devices are the most commonly used type in the United
for attaching steel cable to prevent tampering and to provide
States and use a rotating head to pinch a flexible hose creating
security.
a vacuum to transport the sample to the container. Vacuum
7.1.13 An integral sample container compartment capable
devices (8) are more popular in Europe and use a vacuum
of maintaining samples at 4 to 6°C for a period of 24 h at
pump to transport the sample to the sample container. Suction
ambient temperatures up to 38°C.
liftsamplersareportable,versatileduetotheirlightweightand
7.1.14 Capable of operating in a temperature range from–
can purge the transport line between samples. Their main
10 to 40°C with the exception of the intake hose.
limitationisthattheirliftcapacitywhichisclaimedtorangeup
7.1.15 A purge cycle to flush the sample intake tubing to 9 m but may be significantly less. Also, since suction lift
before and after each collection interval, and a mechanism to
devices use a vacuum to transport samples, they cause some
sense and clear a plugged sample line and then collect the degassing of the sample and are generally unsuitable for
complete sample.
sampling dissolved gases and volatile organic compounds
(VOC). Peristaltic pump samplers can be used to collect
7.1.16 Capable of collecting flow-proportional and time-
composite samples. pressurizedlinesamplesifthepressureislessthan100kPa(15
psi). Vacuum systems must use a flow-through cell which adds
7.1.17 Materials of construction that contact the sample
cost to the system.
must not compromise the integrity of the sample for the
8.3 PressureorForcedFlow—With p
...
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