Standard Operating Procedure
Bureau of Land and Water Quality
Date: May 5, 2015
Doc num: DEPLW0949
Bureau of Land and Water Quality
Division of Environmental Assessment
Lake Assessment Program
Standard Operating Procedure
Collection of Grab (discrete) Samples
1. Applicability. This procedure is used by the Lake Assessment Section, the Maine Volunteer
Lake Monitoring Program (VLMP) and Maine lake assessment cooperators.
2. Purpose. This procedure is used to obtain water samples from discrete locations in the water
column. Grab samples are often used to obtain water for dissolved oxygen / temperature
determinations using chemical kits and to obtain water for total phosphorus analysis, but may be
used for many other parameters.
3. Definitions
3.1. Vertical Sampling Device. Vertical sampling devices hang such
that water passes through the unit in a vertical manner. A Kemmerer
Bottle is a type of vertical sampling device that uses a tripping
mechanism that is attached to a center rod. Numerous other vertical
sampling devices are available; selection is often based on durability,
parameter requirements, and operational effectiveness.
3.2. Horizontal Sampling Device. A horizontal sampling device hangs
such that water passes through the unit in a horizontal manner. A Van
Dorn Bottle is one type of horizontal sampling device. Numerous other
horizontal sampling devices are available; selection is often based on
durability, parameter requirements, and operational effectiveness.
4. Responsibilities
4.1. Certification. It is the responsibility of the individual obtaining this data to maintain current
certification through the VLMP/MeDEP for the parameter(s) he or she collects.
It is the
responsibility of project leaders to make sure field assistants have current training and
certification.
4.2. Data recording. It is the responsibility of the individual obtaining this data to record the
results and additional qualifying information on current field sheets obtained from the agency or
through the VLMP program.
4.3. Data Submissions
4.3.1. Agency Staff. It is the responsibility of the individual obtaining this data to place
completed data sheets in the appropriate hanging gray 'hot file' located in lake assessment staff
area.
4.3.2. VLMP. It is the responsibility of the volunteer monitor to submit completed data sheets to
VLMP staff. The VLMP staff accumulates sheets then scans sheets for placement in DropBox.
Division of Environmental Assessment
Lake Assessment Section
Collection of Grab (discrete) Samples
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Standard Operating Procedure
Bureau of Land and Water Quality
Date: May 5, 2015
Doc num: DEPLW0949
The Regional Data Entry Coordinator accesses the DropBox and enters the data into an approved
data entry program and submits to VLMP staff. The data files are emailed and data sheets are
mailed to Lake Assessment staff at DEP in Augusta, Maine. Some cooperators submit data
sheets and electronic data files directly to Lake Assessment staff. Specific submission deadlines
are established at the beginning of each field season.
4.3.3. Safety. It is the responsibility of all persons aboard the watercraft to wear a personal
floatation device suitable for his or her weight requirements. It is the responsibility of the team
leader in each sampling team to be familiar with DEP safety guidelines for the operation of small
boats with and without motors and to relate pertinent elements to his or her fellow team
member(s).
4.3.4. Equipment Selection. The selection of a grab sampling / discrete sampling device is the
responsibility of the project manager. Selection is often based on durability, operational
effectiveness and parameter requirements. The latter is probably the most important criteria to
evaluate prior to investing in equipment; it is worth consulting with the analytical laboratory and
checking ‘Standard Methods’ to identify parameter collection device restrictions/limitations.
[For example, water samples to be analyzed for metals are best collected in a plastic or Teflon
device.]
4.3.5. Equipment Maintenance. It is the responsibility of the person overseeing a sampling
program to make sure equipment maintenance is routinely performed and documented in a log.
6. Guidelines and Procedures
6.1. Sample Location. Grab samples are most often obtained from waters at the deepest spot on
the lake. The boat must be anchored to avoid drifting. Avoid areas with heavy accumulation of
surface debris and signs of gasoline/oil on the water surface.
6.2. Record Pertinent Information. Label the sample bottle(s) with the lake name (or
abbreviation), 4 digit lake identification number (a/k/a MIDAS number), the sample station (01
is generally the deepest location), date, depth, depth units and type (G for grab). Note pertinent
information in designated areas of field sheet (DEP 142a or equivalent). Any additional
information may be recorded in the comments area. Pens and markers that have water-soluble
inks must not be used. In general, permanent ink pen, pencil or Sharpie permanent markers work
well.
6.3. Surface Grabs. No sampling device is required to obtain a subsurface grab sample. Rinse
the sample container or collection jug with surface water three times; wash hands in surface
water to dislodge any water-soluble contaminants. Obtain sample on opposite side of boat from
where rinsing was done. Invert the container and plunge into water to a depth of about six
inches. Slowly rotate the container to a horizontal or upright position while slowly moving it
away from the boat. The inversion minimizes contamination from debris floating on the water
surface. Movement away from the boat minimizes contamination from hands and the boat. Note
Division of Environmental Assessment
Lake Assessment Section
Collection of Grab (discrete) Samples
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Standard Operating Procedure
Bureau of Land and Water Quality
Date: May 5, 2015
Doc num: DEPLW0949
that some analyses require wearing of Teflon or latex gloves to further reduce risk of
contamination.
6.4. Obtaining Grab Samples with Discrete sampler. Rinse the collection jug or sample
container with surface water three times; wash hands in surface water to dislodge any watersoluble contaminants. Set the tripping mechanism on the sampling device. Rinse the sampling
device in surface water allowing water to drain from spigot(s), if they are designed such that they
trap water. Obtain samples from the opposite side of the boat that rinsing was done. Lower the
sampling device to the desired depth (begin with the shallowest depth and finish with the deepest
sample). Raise and lower the device 3-6 times to make sure that water trapped in the device
during descent has been replaced with water from the desired depth. Fire tripping mechanism.
This is generally accomplished by releasing a weight or messenger that travels down the marked
line to the device causing it to trap water within. Some simpler designs require the user to jerk
the line abruptly causing the device to trap water. Follow the manufacturer’s instructions. Raise
the device. Keep hands away from the spigot opening. Release a small amount of water from
the device to flush the spigot. Rinse the sample container and cap with a small amount of water
three times. Rinse any measuring device in the same manner. Decant the required amount of
water into the measuring device or sampling container in such a way that water does not come in
contact with hands or external surfaces of the sampling device. Repeat process as needed. When
obtaining samples near the sediment, take care not to incorporate sediments into the sample. If
sediment is accidentally collected, discard it. Allow the boat to drift 10-15 feet away by letting
out additional anchor line, rinse the device thoroughly with surface water, and try again lowering
0.5 meters less of line.
6.5. Equipment Care. At the beginning of the season, check the line used to lower the device
for worn spots and knots. If worn spots risk loss of the device, replace the line. Remove all
knots. Check that the depth marks are accurate and that the ‘zero’ meter position is indicated on
the device. Lines on horizontal devices generally use the center of the opening as ‘zero’ for
measuring purposes. Vertical devices may have ‘zero’ at the bottom, center or top of the device;
the position of ‘zero’ should be clearly indicated with permanent marker on the exterior of
vertical sampling devices so the user is better able to avoid contact with sediments.
All moving parts should operate freely. Devices having surgical tubing or a ‘bungie’ that closes
and seals the device will require periodic replacement of those portions as the rubber deteriorates
over time. The manufacturer is generally willing to perform the replacement for a fee. Some
equipment can be repaired by the user.
During the sampling season, it is important to store grab samplers in a cool location out of direct
sunlight. Sunlight will deteriorate rubber portions of the equipment and cause markings to fade.
Grab samplers should be stored either in an open position or be allowed completely dry before
being stored. If stored in a case, the case should be allowed to thoroughly dry before closing.
Grab samplers that are used in saline waters should be well rinsed with fresh water following
each use before stored dry.
Division of Environmental Assessment
Lake Assessment Section
Collection of Grab (discrete) Samples
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Standard Operating Procedure
Bureau of Land and Water Quality
Date: May 5, 2015
Doc num: DEPLW0949
At the beginning and end of the season, grab samplers must be rinsed in distilled or deionized
water, dried, inspected, and stored clean and dry in a dry location out of direct sunlight. Record
‘winterization’ date and equipment repairs in Equipment Log.
6. References
Refer to manufacturer’s instructions for any additional details.
Retired SOPs. The following publications contain procedures that have been used between 1970
and 1996/2001. The current SOP provides more detail than its predecessors and should be used
in place of the following.
Pearsall, W., 1997. "Instruction Manual for Baseline Water Quality Sampling". State of
Maine, Department of Environmental Protection, Division of Environmental Assessment.
DEPLW-96-19-A97.
Potvin, J. and L. Bacon, 1993. "Standard Field Methods for Lake Water Quality
Monitoring". State of Maine Department of Environmental Protection, Division of
Environmental Assessment.
Pearsall, W., Circa 1991. “Understanding Maine’s Lakes and Ponds: A Guide for the
Volunteer Monitoring Program.” State of Maine Department of Environmental Protection,
Division of Environmental Evaluation and Lakes Studies.
Welch, B., J. Potvin and M.E.Dennis. Circa 1981 (various undated editions of ‘Red Book’).
“Understanding Maine’s Lakes and Ponds”. Lay Monitoring Program, Department of
Environmental Protection
Original SOP: Linda Bacon, December 2003
Revision 1: Linda Bacon, May 5, 2015
Division of Environmental Assessment
Lake Assessment Section
Collection of Grab (discrete) Samples
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