~1:::11211 ELECTRIC POWER 1::1- RESEARCH INSTITUTE Memorandum 

Date: May 16, 2007 

TO: Ron Jordan, EPA 

FROM: Naomi Goodman, EPRI 

SUBJECT: SUPPLEMENTAL INFORMATION: SAMPLING COAL-FIRED 

ELECTRIC POWER PLANT WASTEWATERS 

The following information provides a detailed discussion of best practices for collection of 

wastewater samples during the EPA Steam Electric Power Generating Point Source Category 

sample collection effort. This memorandum supplements EPRI's document Sampling and 

Analytical Plan Guidance for Water Characterization ofCoal-Fired Steam Electric Utility 

Facilities, March 2007. Topics covered in this memorandum include best sampling practices for 

each wastewater matrix, collection of split samples, and other recommendations. 

Summary of Sampling Recommendations by Wastewater Stream 

EPA's Generic Sampling and Analysis Plan for Coal-Fired Steam Electric Power Plants, May 

11, 2007 identifies six target wastewaters. Supplemental guidance on sampling and analysis for 

the EPA target wastewaters and other potential sampling locations is summarized below. 

Ash Pond Influent 

Identifying the best sample location in an ash pond can be challenging, and will be site-specific. It 

may not be possible to find one spot where all flow into an ash pond is mixed together, especially 

if influent pipes come in at different points along the ash pond shoreline. If all inputs to the pond 

combine into a single flow and are channelized within the ash delta, it may be possible to collect a 

sample at the downstream (in-pond) end of the ash delta. This will depend upon accessibility and 

plant safety requirements. 

The ash pond int1uent sample should be collected as a composite, due to variations in the t1ow 

into a pond \vith sluice cycling and other plant processes. Composites can be collected with an 

automatic sampler or by pooling multiple manual grab samples collected over time. If manual 

composites are used, the composite should encompass at least one sluice cycle. If automatic 

compositers are used, a 24-hour composite can be collected. In this case, care will be needed to 
position the sampling suction line to avoid clogging and to check to ensure water is being 

collected. 

Summary of Sampling Recommendations for Wastewater Streams 

Sample Clean or Recommended Analytical Considerations 

Location Conventional Sample Type 

Sampling 

Ash Pond Conventional Composite, due Will have high solids and possible 

Influent to variations in chemical interferences 

sluicing 

Ash Pond Clean Grab Samples should be low in suspended 

Effluent solids (<30 mg/L), and relatively low in 

matrix interferences (unless FGD 

discharges to pond). 

FGD Treatment Conventional Composite (see Will have high solids and chemical 

System Influent discussion interferences 

below) 

FGD Treatment Clean Grab (assuming Will have high chemical interferences 

System After system has 

Primary equalization 

Clarification tank) 

FGD Treatment Clean Grab (assuming Will have high chemical interferences 

System Effluent system has 

equalization 

tank) 

Final Effluent Clean Grab Expect low matrix interferences 

Source Water Clean Grab Expect low matrix interferences 

If a sample must be collected before bulk ash settling (i.e., early in the delta), the composite 

should be shaken and then allowed to settle for 1 hour prior to decanting the supernatant sample 

containers. It is recommended that filtering for dissolved metals analysis be done by pumping 

some of the composited sample, after settling, through an in-line cartridge filter into sample 

containers. 

Ash Pond Effluent 

Samples should be pumped directly from the ash pond discharge stream. Compositing is not 

essential, due to mixing within the pond. Filtering for dissolved metals analysis should be 

accomplished by pumping water from the pond through an in-line cartridge filter into cleaned 

sample containers. 

I 
.. 

It is recommended that filtering for dissolved metals analysis be accomplished by pumping some 

of the sample through a filter into sample containers. 

FGD Treatment System Influent 

FGD blowdown quality may be highly variable in flow and composition, and contains high solids. 

Samplers should consult the FGD system operators during the site reconnaissance to answer the 

following questions: 

• Does FGD wastewater flow continuously to the treatment system? 

• Does flow vary over time? 

• Is solids loading in the FGD wastewater consistent, or does it change with time or fuel 

changes? 

The answers to these questions will determine the amount of coordination with operators that will 

be required in collecting the sample. 

A composite sample is recommended. The composite should consist of a series of grab samples, 

collected over time and mixed together in a large container. A manual composite is recommended 

rather than an automatic sampler at this location, because the high-solids stream (potentially 5% 

or more) could plug an automatic sampler's suction hose. 

It is recommended that filtering for dissolved metals analysis be done by pumping some of the 

composited sample, after settling, through an in-line cartridge filter into sample containers. 

Samples should not be collected from the treatment system equalization tank if any liquid or 

sludge streams other than FGD blowdown are discharged to the tank. 

Operating data and observations of the wastewater flow and color should be recorded during 

sampling, as these observations will be critical to interpretation of the analytical results. 

FGD Treatment System Mid-Point (After Primary Clarification) and Effluent 

Samples should be taken directly from a sampling tap or pumped directly from the effluent tank. 

Assuming there is an equalization tank in the system, compositing is not essential. If sampling 

from a tank, samples should be collected by pumping rather than dipping, to avoid collecting 

floating materials. If sampling from a tap, it is recommended to collect samples for dissolved 

metals analysis by filling a cleaned container from the tap, mixing the collected water, and then 

pumping the collected water through an in-line cartridge filter into sample containers. Extra filters 

should be made available, as solids in the effluent may plug the filter. 

Final Effluent 

Samples should be collected directly from the effluent discharge. Compositing is not essential 

unless multiple discharge points arc sampled at one facility. Filtering for dissolved metals 
analysis should be accomplished by pumping water from the effluent location through an in-line 

cartridge filter into sample containers. If samples are collected from a sample tap, it may be better 

to collect into a clean container, and then filter through the filter cartridge. 

Source Water Samples 

In order to determine the amount of pollutants that are contributed from the source water body, a 

source water sample should be collected. This sample should be collected and analyzed using 

trace level clean techniques. If dissolved samples are to be collected, the sample should be 

pumped through a filter cartridge. If samples are collected from a sample tap, it may be better to 

collect into a clean container, and then filter through the filter cartridge. 

Collection of Split Samples 

The goal of split sample collection is to generate paired samples that represent the same water 

composition as closely as possible. The recommended techniques for preparing splits are: 

1. Pumped samples (effluents and other relatively low solids streams)- use a Y-splitter to 

simultaneously collect paired samples for each parameter. An equal flow should be routed 

into each ofthe paired bottles. Pre-cleaned Y -splitters and pump tubing should be 

provided for each sampling location and discarded after sampling is completed, to avoid 

cross-contamination. Oil and grease (HEM/SGT-HEM) should not be sampled through a 

splitter. 

2. Pumped or grab samples (high solids streams) excluding solids, and filtered samplescollect sufficient sample for paired bottles into a pre-cleaned, dedicated container large 

enough for both the EPA and split sample volume. Shake container or mix the water 

thoroughly with an agitator, let settle, and pump from the supernatant through a Y-splitter 

into paired sample bottles. 

3. Pumped or grab samples (high solids streams) including solids -collect sufficient sample 

for paired bottles in a pre-cleaned, dedicated container large enough for both the EPA and 

split sample volume. Shake container or mix the water thoroughly with an agitator, and 

while still well mixed, pump through a Y-splitter into paired sample bottles. 

The total volume that must be collected at each sampling location is calculated in Attachment A. 

The volume was calculated from Table 2-3 in the EPA's Generic Sampling and Analysis Plan, 

May 11, 2007. It was assumed for these calculations that a field duplicate of the split samples 

will not be required, and that MS/MSDs for the split samples will be prepared from the same 

container as the parent sample. The total volume of sample required at each sampling location if 

samples will be submitted for clean metals analysis is 27.4 liters (7.2 gallons). If only 200-series 

metals analyses will be required, the total volume is 19.4liters (5.1 gallons). 

To collect a composite sample sufficient for all parameters and splits, a large container will be 

needed, such as a plastic carboy or bucket of appropriate materials, cleaned per specifications of 

the clean sampling methods. Composites should be kept on ice while they are being collected; a 

larger outer container full of ice can be placed around the container used to collect the composite. 

.. 
.. 

Other Field Sampling and Analytical Considerations 

• Ensure that sufficient ultrapure, analyte-free water is sent from the laboratory for preparing 

blanks. For example, if a bottle blank, field blank and equipment blank are to be collected for 

the full suite of parameters in EPA's plan, at least 32 liters of water from the laboratory will 

be needed. 

• Guidance should be given to analytical laboratories on which samples are from the FGD 

wastewater (influent, midpoint and effluent) and ash pond influent locations, as these will 

likely pose matrix interference challenges for the laboratory. 

• It is recommended that at least one sample of each matrix (FGD water, ash pond water) be 

collected in advance of the EPA site sampling visits, so that the EPA laboratory can practice 

working with the matrices involved to help avoid problems with the actual samples. 

Cc: 

P. Chu, EPRl 
Attachment A. Total Sample Volume Requirements for EPA and Split Samples into One Collectio

Container 

.: 

" 

, .,_ 

··"' . ; ,,. EPA EPAQC Split Split 

' ; 

Low-Level ' •' ' . , Sarqple Volume MS/ 

' 

Method? Parameter ; . MSD* "

Classical 

BOD5 1 1 X X 

Group I (a) 1.5 1.5 1.5 X 

Group II (b) 1.1 ** 2 I X 

HEM/SGT-HEM I 2 X X 

Metals 

X Low-level total mercury (Method 163 1) 0.5 0.5 0.5 

X Low-level dissolved mercury (Method 1631) 0.5 0.5 0.5 

X Low-level total elements by ICP/MS 0.5 0.5 1 

(9 elements, Method 1638) 

X Low-level dissolved elements by ICP/MS 0.5 0.5 1 

(9 elements, Method 1638) 

X Low-level hexavalent chromium (Method 1636) 0.5 0.5 1 

Routine hexavalent chromium 0.2 0.2 

Total metals, 27 element quantitation 0.5 0.5 I 

(Methods 200.7, 200.8, 200.9) 

Dissolved metals, 27 element quantitation 0.5 0.5 I 

(Methods 200.7, 200.8, 200.9) 

Speciation of As and Se X X 0.375 

TOTAL VOLUME without Low-Level Metals (liters) 5.8 7.7 5.9 

TOTAL VOLUJ\!E with Low-Level Metals (liters) 8.3 10.2 .__ 9.0 

-

(a) Group I includes TSS, TDS, sulfate, and chloride. 

(b) Group II includes ammonia as nitrogen, nitrate/nitrite as nitrogen, TKN, and total phosphorus. 

*-Note: It is recommended that matrix spike I matrix spike duplicates be collected in the same bottle as the native sample, with a large

sufficient volume. This is recommended in order to ensure that the same matrix is collected. 

**- per EPA Sampling Plan