Wastewater sampling and test procedures practice questions
20 free practice questions from 40 CFR 136.1 to 136.3. Each answer is explained and linked to the rule it comes from.
Wastewater sampling and test procedures
20 questions across 6 topics. After each answer you see why it is right, with a link to the official source.
Tip: press A, B, C or D to answer and Enter for the next question. Nothing you answer leaves your browser.
Review all 20 questions
Prefer to read? Here is every question in the Wastewater sampling and test procedures set, grouped by topic. Open a question to see the answer, why it is right and the official source.
Applicability and definitions
1. Under 40 CFR 136.1(a)(3), the Part 136 procedures must be used for measurements required for which of these?
- A. Laboratory proficiency tests a lab runs for its own customers
- B. Certifications issued by States pursuant to section 401 of the Clean Water Act
- C. Air emission permits issued under the Clean Air Act
- D. Monitoring of drinking water at the consumer's tap
Show answer
Answer: B. Certifications issued by States pursuant to section 401 of the Clean Water Act
Section 136.1(a)(3) lists "Certifications issued by States pursuant to section 401 of the Clean Water Act (CWA), as amended."
Source: eCFR: 40 CFR 136.1, Applicability (as of Nov 4, 2026)
2. Besides Part 136 itself, which part of title 40 does 136.1(b) name for performing the measurements required for a sewage sludge permit application under section 405(f) of the Clean Water Act?
- A. Part 503
- B. Part 261
- C. Part 60
- D. Part 141
Show answer
Answer: A. Part 503
"The procedure prescribed herein and in part 503 of title 40 shall be used to perform the measurements required for an application submitted to the Administrator or to a State for a sewage sludge permit under section 405(f) of the Clean Water Act".
Source: eCFR: 40 CFR 136.1, Applicability (as of Nov 4, 2026)
3. For the purposes of the NPDES program, what does 136.1(c) require when more than one test procedure is approved under Part 136 for a pollutant?
- A. The oldest approved procedure must be used
- B. The permittee may use whichever approved procedure costs the least
- C. The laboratory must run every approved procedure and report the average
- D. The test procedure must be sufficiently sensitive as defined at 40 CFR 122.21(e)(3) and 122.44(i)(1)(iv)
Show answer
Answer: D. The test procedure must be sufficiently sensitive as defined at 40 CFR 122.21(e)(3) and 122.44(i)(1)(iv)
"When more than one test procedure is approved under this part for the analysis of a pollutant or pollutant parameter, the test procedure must be sufficiently sensitive as defined at 40 CFR 122.21(e)(3) and 122.44(i)(1)(iv)."
Source: eCFR: 40 CFR 136.1, Applicability (as of Nov 4, 2026)
4. Under the definition of detection limit in 136.2(f), the analyte concentration must be distinguishable from what?
- A. The permit limit for the pollutant
- B. The method blank results
- C. The highest calibration standard
- D. The concentration in the upstream receiving water
Show answer
Answer: B. The method blank results
Detection limit is "the minimum concentration of an analyte (substance) that can be measured and reported with a 99% confidence that the analyte concentration is distinguishable from the method blank results".
Approved test procedures and alternatives
5. Under 136.3(a), what controls when the reporting requirements of 40 CFR parts 122 and 125 conflict with reporting requirements associated with a listed method?
- A. The provisions of 40 CFR parts 122 and 125
- B. Whichever requirement the laboratory selects
- C. The stricter of the two, as chosen by the analyst
- D. The method's own reporting requirements
Show answer
Answer: A. The provisions of 40 CFR parts 122 and 125
In that event, "the provisions of 40 CFR parts 122 and 125 are controlling and will determine a permittee's reporting requirements."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
6. Under 136.3(c), when the Director establishes limitations on the discharge of a parameter for which there is no test procedure in Part 136 or in 40 CFR parts 405 through 499, who specifies the test procedure?
- A. The manufacturer of the sampling equipment
- B. The permittee's contract laboratory
- C. The Director
- D. The Alternate Test Procedure Program Coordinator
Show answer
Answer: C. The Director
"In these instances the test procedure shall be specified by the Director."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
7. Under 136.3(d), upon whose recommendation may the Administrator approve additional alternate test procedures for nationwide use?
- A. The Alternate Test Procedure Program Coordinator, Washington, DC
- B. The permittee's laboratory director
- C. The Regional Administrator of the Region where the discharge occurs
- D. The State drinking water administrator
Show answer
Answer: A. The Alternate Test Procedure Program Coordinator, Washington, DC
"The Administrator may approve additional alternate test procedures for nationwide use, upon recommendation by the Alternate Test Procedure Program Coordinator, Washington, DC."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
Table II and limited use changes
8. Under 136.3(e), how does the information in Table II rank against information in specific methods?
- A. Specific methods always take precedence over Table II
- B. The analyst chooses between them for each sample
- C. Table II applies only when a method gives no holding time
- D. Information in the table takes precedence over information in specific methods or elsewhere
Show answer
Answer: D. Information in the table takes precedence over information in specific methods or elsewhere
"Information in the table takes precedence over information in specific methods or elsewhere."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
9. Under 136.3(e), how may applications for limited use changes in preservation, containers or holding times for samples from a specific discharge be made?
- A. By a note in the laboratory's bench sheet, with no application needed
- B. By letters to the Regional Alternative Test Procedure (ATP) Program Coordinator or the permitting authority in the Region in which the discharge will occur
- C. By publishing a notice in the Federal Register
- D. By a phone call to the sampling equipment vendor
Show answer
Answer: B. By letters to the Regional Alternative Test Procedure (ATP) Program Coordinator or the permitting authority in the Region in which the discharge will occur
"Applications for such limited use changes may be made by letters to the Regional Alternative Test Procedure (ATP) Program Coordinator or the permitting authority in the Region in which the discharge will occur."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
10. What time frame does 136.3(e) set for the decision on a request to deviate from the prescribed Table II requirements?
- A. Within 10 days of receipt
- B. Within 1 year of receipt
- C. Within 30 days of the first sample
- D. Within 90 days of receipt of the application by the Regional Administrator
Show answer
Answer: D. Within 90 days of receipt of the application by the Regional Administrator
A decision on such a request "will be made within 90 days of receipt of the application by the Regional Administrator."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
Containers and preservation
11. In footnote 1 to Table II, what does the container code "PA" mean?
- A. Polyethylene only
- B. Plain amber glass
- C. Any plastic that is made of a sterilizable material (polypropylene or other autoclavable plastic)
- D. Low density polyethylene
Show answer
Answer: C. Any plastic that is made of a sterilizable material (polypropylene or other autoclavable plastic)
Footnote 1 says "PA" is "any plastic that is made of a sterilizable material (polypropylene or other autoclavable plastic)", while "LDPE" is "low density polyethylene."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
12. Under footnote 2 to Table II, for a composite sample collected with an automated sampler, when must the sample be refrigerated at ≤6 °C, unless Table II or the method specifies otherwise?
- A. During collection
- B. Only after it arrives at the laboratory
- C. Only if the holding time will exceed 48 hours
- D. Only after the last aliquot is analyzed
Show answer
Answer: A. During collection
For such a composite sample, "refrigerate the sample at ≤6 °C during collection unless specified otherwise in this Table II or in the method(s)."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
13. Under footnote 2 to Table II, if a composite measurement is required but a composite sample would compromise sample integrity, how are the individual grab samples collected at prescribed time intervals to be analyzed?
- A. Only the last grab sample is analyzed
- B. Only the grab sample with the highest reading is reported
- C. Separately, with the concentrations averaged
- D. They are poured together in the field without any check
Show answer
Answer: C. Separately, with the concentrations averaged
"Grab samples must be analyzed separately and the concentrations averaged." They may also be composited in the laboratory only "if the compositing procedure produces results equivalent to results produced by arithmetic averaging of results of analysis of individual grab samples."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
14. Under footnote 3 to Table II, when a sample is to be shipped by common carrier or sent via the U.S. Postal Service, who is responsible for ensuring compliance with the Department of Transportation Hazardous Materials Regulations?
- A. The permitting authority
- B. The receiving laboratory only
- C. The Regional ATP Coordinator
- D. The person offering such material for transportation
Show answer
Answer: D. The person offering such material for transportation
"The person offering such material for transportation is responsible for ensuring such compliance."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
15. Under footnote 18 to Table II, to which samples does the preservation temperature not apply?
- A. Samples shipped overnight
- B. Samples collected in winter
- C. Samples held in glass containers
- D. Samples that are analyzed immediately (less than 15 minutes)
Show answer
Answer: D. Samples that are analyzed immediately (less than 15 minutes)
"The preservation temperature does not apply to samples that are analyzed immediately (less than 15 minutes)."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
16. Footnote 19 to Table II says an aqueous sample may be collected and shipped without acid preservation. Unless the sample must be analyzed within 24 hours of collection, when must the acid then be added?
- A. Just before the analysis begins
- B. At least 24 hours before analysis
- C. Only when the sample is a soil or sediment sample
- D. Within 90 days of sample collection
Show answer
Answer: B. At least 24 hours before analysis
"An aqueous sample may be collected and shipped without acid preservation." The acid must be "added at least 24 hours before analysis to dissolve any metals that adsorb to the container walls"; "If the sample must be analyzed within 24 hours of collection, add the acid immediately (see footnote 2)."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
Holding times
17. Footnote 4 to Table II says the times listed are the maximum times samples may be held before the start of analysis. What is a permittee or monitoring laboratory obligated to do if it knows that a shorter time is necessary to maintain sample stability?
- A. Hold the sample for the full time listed, because Table II takes precedence
- B. Obtain a variance from the Regional ATP Coordinator before analyzing the sample sooner
- C. Hold the sample for a shorter time
- D. Add a second preservative so the listed holding time can still be used
Show answer
Answer: C. Hold the sample for a shorter time
Footnote 4 says "The times listed are the maximum times that samples may be held before the start of analysis and still be considered valid." It adds: "A permittee or monitoring laboratory is obligated to hold the sample for a shorter time if it knows that a shorter time is necessary to maintain sample stability."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
18. Under footnote 4 to Table II, when does the holding time begin for a set of grab samples composited in the field or laboratory?
- A. At the time of collection of the last grab sample in the set
- B. At the time of collection of the first grab sample in the set
- C. When compositing in the laboratory is finished
- D. At midnight on the day of collection
Show answer
Answer: A. At the time of collection of the last grab sample in the set
"For a set of grab samples composited in the field or laboratory, the holding time begins at the time of collection of the last grab sample in the set."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
19. Under footnote 4 to Table II, what two things are needed before samples may be held for longer periods than the times listed?
- A. A signed chain-of-custody form and a cooler with ice
- B. Data on file showing the analytes are stable for the longer time for the specific types of samples, and a variance from the Regional ATP Coordinator under 136.3(e)
- C. Approval from the sampling equipment manufacturer and a second analyst
- D. A written note from the plant operator and a duplicate sample
Show answer
Answer: B. Data on file showing the analytes are stable for the longer time for the specific types of samples, and a variance from the Regional ATP Coordinator under 136.3(e)
Samples may be held longer "only if the permittee or monitoring laboratory have data on file to show that, for the specific types of samples under study, the analytes are stable for the longer time, and has received a variance from the Regional ATP Coordinator under § 136.3(e)."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)
Footnotes for specific tests
20. Footnote 23 to Table II extends the fecal coliform holding time for sewage sludge (biosolids) only, using EPA Method 1680 or 1681. Which sample types does it list?
- A. All sewage sludge samples regardless of treatment
- B. Raw influent and primary effluent
- C. Class A composted, Class B aerobically digested, and Class B anaerobically digested
- D. Final effluent samples from lagoons
Show answer
Answer: C. Class A composted, Class B aerobically digested, and Class B anaerobically digested
The extension covers "the following sample types using either EPA Method 1680 (LTB-EC) or 1681 (A-1): Class A composted, Class B aerobically digested, and Class B anaerobically digested."
Source: eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)