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RESPONSE TO COMMENTS 

City of Puyallup

Wastewater Treatment Plant

NPDES Permit WA0037168

September 23, 2014

On April 6, 2013, the U.S. Environmental Protection Agency (EPA) issued a public notice 

for the reissuance of the City of Puyallup Wastewater Treatment Plant (WWTP) National 

Pollutant Discharge Elimination System (NPDES) Permit No. WA0037168. This Response 

to Comments provides a summary of significant comments and provides corresponding EPA 

responses. The comments resulted in the following changes to the permit:

 Acute Whole Effluent Toxicity (WET) testing is eliminated and the trigger for 

accelerated testing and the Toxicity Reduction Evaluation is changed to a TUc of 1.9.

The WET test species and tests are clarified. 

 The reporting date for WET testing is changed “from with the discharge monitoring 

reports (DMR) for the month following sample collection” to “with the DMRs for the 

month following the receipt of the results from the laboratory.”

 The typographical error referencing Part II.G. in Condition III.I., Public Notification 

is corrected to reference Part II.F.

 The effluent limitation range for pH is increased from a lower value of 6.4 in the draft 

permit to a lower value of 6.1 in the final permit. The final pH range is the same as in 

the previous permit.

 The arsenic Minimum Level (ML) for effluent monitoring in Table 2 of the permit is 

changed from 10 μg/L to 0.5 μg/L.

 Condition I.B.7. is revised to allow a method that detects and quantifies arsenic.

 Condition I.D.8. is revised to allow a method that detects and quantifies arsenic.

 The frequency of toxic organics sampling required under the pretreatment monitoring 

requirements, Part II.A.8.i) is clarified and established as once per year. 

 Exceptions to pH violations applicable to continuous monitoring are added.

 To allow sufficient time for completion, the submission of the local limits evaluation 

is delayed to December 31, 2015.
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After consultation with the Puyallup Tribe and as required by the final 401 Certification the 

following conditions are added to the final permit:

1. Quarterly monitoring of endosulfan monitoring is required for five years. This will 

allow a sufficient number of samples to determine if the discharge has reasonable 

potential to cause or contribute to a violation of the Puyallup water quality standards 

for endosulfan.

2. A study is added to the permit to identify the source of lead and zinc in the effluent 

and identify opportunities for reduction. Lead and zinc effluent limitations are 

eliminated in the reissued permit based on the Puyallup’s authorized mixing zone. 

Authorization of a mixing zone is contingent on this added study. 

A second condition of the mixing zone authorization is monitoring at the edge of the 

mixing zones. This condition is added to the permit. 

3. A Mercury Minimization Plan and annual status report is added to the Permit.

4. The Tribe is authorizing a mixing zone for lead, zinc and mercury as identified in the 

table below. With these mixing zones, there is no reasonable potential to violate the 

water quality standards for these pollutants.

Minimum Mixing Zone for No Reasonable

Potential to Violate the Puyallup Water Quality Standards

(Percent of Receiving Water Flow)

lead zinc Mercury

Acute End of Pipe 2.1 End of Pipe

Chronic 3.3 4.0 20

Comments were received from the following:

Robert Andreotti, Director of Public Works, City of Puyallup (City)

1. Comment: With the exception of one Total Recoverable Zinc result in November 2006, 

the violations listed below are in error.

1. 31 July 2009 – Total Recoverable Mercury. The value reported was above the 

threshold of the method detection limit, 0.0001 μg/L, but too low as to be 

quantifiable. Puyallup has never had an effluent mercury result that exceeds 

limitations.

2. 30 Jun 2006 – Nitrogen Ammonia, Total –The origin of the values listed are 

unknown. Puyallup’s records indicate that for the month of June 2006 the 
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monthly ammonia average was 0.49 mg/L and that the daily maximum value was 

1.30 mg/L. Both values are well below permit limitations and consistent with 

typical concentrations.

3. 30 April 2008 – Lead, Total Recoverable – The values reported on Puyallup’s

DMR for April 2008 list the monthly average value of 0.5 μg/L and a monthly 

maximum value of 0.5 μg/L. These values are well below the limits of 6.1 μg/L 

and 10.5 μg/L, respectively. 

Response: The EPA agrees the Fact Sheet Table 1 listing of total recoverable mercury 

and total recoverable lead as violations is an error. The listing of nitrogen ammonia as a 

violation could not be verified. This comment does not result in any changes to the 

permit.

2. Comment (City): The effluent limits in Table 3 of the Fact Sheet for the draft permit 

contain the following errors.

BOD5, mg/L, lb/day, percent removal – A sampling frequency of 5 episodes per 

week is listed; whereas, Puyallup’s existing permit and draft permit list 3 episodes 

per week.

TSS, mg/L, lb/day, percent removal - A sampling frequency of 5 episodes per 

week is listed; whereas, Puyallup’s existing permit and draft permit list 3 episodes 

per week.

Fecal Coliform Bacteria, #/100 ml - A sampling frequency of 5 episodes per week 

is listed; whereas, Puyallup’s existing permit and draft permit list 3 episodes per 

week.

pH, std. units - The Maximum Daily Limit for Puyallup’s existing permit is listed 

in the Fact Sheet as 6.4 – 9.0 standard units; whereas, the actual existing permit 

limitation is 6.1 to 9.0.

Response: The EPA agrees with the comment, the Fact Sheet was incorrect and 

inconsistent with the draft permit. The sampling frequency for BOD5, TSS, and fecal 

coliform was correct in the draft and final permit and is 3 episodes per week. The percent 

removal for BOD5 and TSS is calculated from the average values for the month. The 

effluent limit for pH in the final permit is revised (see response to Comment # 15). 

3. Comment: Fact sheet Table 4 - Receiving Water Monitoring Requirements in the

Puyallup River does not contain monitoring requirements for mercury; whereas, annual 

testing is required in the draft permit. Additionally, copper is listed without indicating 

speciation; whereas, in the draft permit it is listed as dissolved.

Response: The receiving water monitoring requirements in the permit are correct and are 

required. Annual mercury receiving water monitoring is required and dissolved copper is 

the species required to be reported. 
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4. Comment: Fact Sheet Section E. Outfall Evaluation states: 

“In early 1998 the City modified the existing diffuser to prevent damage by gravel

and rocks. The diffuser ports are now angled downstream with a “Tide Flex” valve

connected with a neoprene sleeve and flange. To ensure that the new diffuser is not 

damaged by sediment deposition, the draft permit requires the City to conduct an

annual outfall evaluation.”

The draft permit does not contain this requirement.

Response: The fact sheet was inconsistent with the permit. However the permit is the 

enforceable document, not the fact sheet. In accordance with the permit, the City is not 

required to conduct an outfall evaluation.

5. Comment: The Fact Sheet requires the City to conduct a comprehensive 

infiltration/inflow study identifying the causes of untreated/primary treated overflows and 

submit a report within three years that contains deadlines for correcting the problems. 

However, this requirement is not in the draft permit and Puyallup objects to its inclusion 

for the reasons below.

1. The Fact Sheet states that Puyallup is to perform ...evaluation of the sewerage facility 

and a system-wide inventory/evaluation survey that identifies the causes of the 

untreated/primary-treated overflows.... The word ‘causes’ suggests that Puyallup has 

had an ongoing problem with untreated/primary-treated overflows. However, with the 

exception of one equipment failure that resulted in a limited duration overflow in 

2013, the Puyallup treatment plant has had no other overflows in the fifteen years 

since a major upgrade that began in 2008.

2. The design of the Puyallup’s facility does not physically allow for the intentional 

bypass of primary or partially treated wastewater.

3. The City completed a comprehensive city-wide infiltration and inflow study in 2012 

where 24 individual basins were monitored and the volume of infiltration and inflow 

was characterized.

4. Puyallup continues in 2014 to identify and repair major sources of infiltration and 

inflow with $300,000 allocated in its capital budget to infiltration/inflow reduction 

and dry-weather smoke-testing pending for later in 2014. An additional $250,000 

allocated to system improvements.

Response: The fact sheet is inconsistent with the permit. The permit, not the fact sheet is 

the enforceable document. Since the permit does not contain this requirement, the City is 

not required to conduct a comprehensive infiltration/inflow study.

6. Comment: Puyallup strongly objects to the requirement to sample for arsenic in the 

Puyallup River. Although the CWA may authorize EPA to require sampling and reports 
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the basis of the requirement does not seem justified by EPA’s or the Department of 

Ecology’s reckoning.

The Department of Ecology study, Results and Recommendations from Monitoring 

Arsenic Levels in 303(d) Listed Rivers in Washington (Ecology publication number 02-

03-045) (Ecology Report), states: 

“There is significant uncertainty regarding the accuracy of the current 

arsenic criteria for human health. Even EPA is reluctant to impose the

 criteria (62 FR 42179, August 5, 1997) that they promulgated on Washington

 State through the National Toxic Rule.”

Low-level sampling and analysis is fraught with opportunities for accidental 

contamination and erroneous results. Puyallup does not possess the expertise to handle or 

filter samples for dissolved arsenic. The rigorous sampling, handling, and analytic 

requirements are detailed in the Ecology report as well as in EPA Method 1669. As stated 

in the Ecology Report, sampling and analytic costs are high for the different speciations 

of arsenic. Puyallup does not believe it has the responsibility or capability to recharacterize or augment the arsenic data collected by the Department of Ecology. This is 

a task best left to the expertise of a regulatory agency such as EPA or the Department of 

Ecology. 

Response: The EPA believes the City has the capability and responsibility to conduct 

the sampling for total and inorganic arsenic in the Puyallup River.

Federal regulations at 40 CFR122.44 (vii) states 

“When developing water quality-based effluent limits under this paragraph the 

permitting authority shall ensure that:

(A)The level of water quality to be achieved by limits on point sources established 

under this paragraph is derived from, and complies with all applicable water 

quality standards;...”

The Puyallup Water Quality Standards contain both total arsenic criteria for protection 

of aquatic life and inorganic arsenic criteria for protection of human health. It is the 

responsibility of the City of Puyallup to provide the monitoring necessary to ensure that 

its discharges comply with the water quality standards.

On page 3.2 of EPA’s Permit Writers Manual,, September 2011, Section 3.2 Major 

Components [of an NPDES permit], Permit Bullet 3 states:

All NPDES permits consist, at a minimum of...

“Monitoring and Reporting Requirements: Used to characterize wastestreams and 

receiving waters (emphasis added) ...”

The permit includes both inorganic and total recoverable arsenic monitoring for 

reasonable potential determination of aquatic life and human health arsenic criteria. 

Monitoring for the Ecology Report conducted in 2002 at the Meridian Street Bridge 

(Monitoring Station 10A070) upstream of the discharge only included one inorganic 
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arsenic sample, the speciation of the criteria for protection of human health. One sample 

is inadequate to determine reasonable potential for violations of the human health 

standard for arsenic. The ambient water quality data for inorganic arsenic is necessary to 

assess the reasonable potential for the effluent to exceed the inorganic arsenic criteria.

Therefore inorganic receiving water monitoring is retained. 

The permit is unchanged. 

7. Comment: The Ecology Report contains other salient facts that argue against the 

proposed arsenic sampling:

...the comparability of the data is confounded by differences in the year and season of 

collection, sampling procedures, analytical methods, and detection limits.

Response:

 To address concerns about variation in arsenic concentration by year, the effluent 

and receiving water monitoring is required over five years.

 To address concerns about variation in arsenic concentrations over different 

seasons, effluent and receiving water monitoring is required to occur during all 

four seasons.

 As the City reported on Application Form 2A Part D, Supplemental Application 

Information, the analytical method for arsenic is 200.8. This method will allow a 

minimum level (ML) of 0.5 μg/L. Table 2 in the permit is revised to include an 

ML of 0.5 μg/L for arsenic.

 The total recoverable, dissolved and inorganic arsenic monitoring is required by 

the Puyallup Tribe’s 401 Certification and must be included in the permit under 

Clean Water Act Section 401(d).

Arsenic monitoring is retained in the final permit.

8. Comment: The Ecology Report stated arsenic levels in Washington rivers and streams 

should be attributed to natural sources, unless shown otherwise. The Ecology Report also 

stated exceedances of the National Toxics Rule arsenic criteria are to be expected in 

Washington rivers and streams. Additionally, as noted in the Department of Ecology 

report, background concentrations of arsenic in the Puyallup River already exceed Tribal 

human health standards by nearly 56 times.

Response: The permit is consistent with the recommendations in the Ecology 

Report. The Ecology Report for the Puyallup River shows background concentrations of 

total recoverable arsenic exceeding the human health criteria. However human health 

criteria is based on inorganic arsenic The Ecology Report contained only one sample of 

inorganic arsenic. One sample is inadequate for a reasonable potential determination for 

arsenic discharges to violate the water quality standards for human health. Adding to the 
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uncertainty of inorganic arsenic in the receiving water is provided in a conclusion in the 

Ecology Report on page 14 qualifying its data by the statement: “These dissolved data 

may underestimate total inorganic arsenic by a substantial amount.”

The Ecology Report is inconclusive regarding the source of arsenic in the Puyallup 

River. If the exceedance is from anthropogenic sources as demonstrated by the 

monitoring the sampling will aide in an evaluation of the need for listing of arsenic in the 

vicinity of the discharge. 

Further, the Puyallup Tribe is requiring the monitoring of arsenic in the 401 Certification. 

The Ecology Report on page 16 states “it is not possible to state with certainty what the 

natural background is for arsenic in Washington rivers and streams. Additional 

monitoring will help identify natural background.” The permit provides this additional 

monitoring. 

The Ecology Report states “Water quality data considered for future 303(d) arsenic 

listings should clearly demonstrate that any exceedances of standards are due to 

anthropogenic sources, and should include some measurement of total inorganic arsenic”. 

The permit provides the monitoring recommended by the Ecology Report. As the fact 

sheet states the permit requires the City to conduct a limited round of inorganic arsenic 

monitoring to determine whether or not there should be a follow up study to determine if 

arsenic in the treatment plant effluent is naturally-occurring arsenic, or if it is of 

commercial or industrial origin.

The permit is unchanged. 

9. Comment: Puyallup operates an Industrial Pretreatment Program required, approved, 

and periodically audited by EPA. All commercial and industrial users complete a 

comprehensive survey to determine the nature of their business and the character of 

pollutants discharged. Users either receive discharge permits from the City or Letters of 

Authorization (LOA) to discharge. Puyallup has an arsenic limitation in its sewer use 

ordinance that was developed using EPA methodology and approved by EPA. Puyallup 

has no known commercial or industrial contributors of arsenic. Consequently, arsenic 

sampling is not justified on the basis of determining if arsenic in the treatment plant 

effluent is naturally-occurring arsenic, or if it is of commercial or industrial origin.

While it is reasonable to conclude that potable water likely contributes arsenic to the 

wastewater effluent it is not contributed at the concentrations given in the Fact Sheet. 

Response: The City’s arsenic limitation in its sewer use ordinance and the arsenic in the 

potable water supply are not adequate to characterize effluent discharges for arsenic. The 

influent arsenic monitoring and concentrations in the potable water supply may not be 

representative of arsenic in the effluent. Arsenic in the potable water supply could 

explain the source of arsenic in the Puyallup WWTP effluent but it is the effluent that 

must be monitored. Monitoring effluent discharges is required to characterize the 
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discharges. The permit requires monitoring of the effluent for inorganic arsenic since the 

criteria for protection of human health is inorganic arsenic not total arsenic.

The Department of Ecology determined in 2002 that arsenic concentrations in 

Washington rivers and streams are typically in the range of 0.2 - 1.0 ug/L, whereas 

concentrations greater than 2 to 5 ug/L may indicate contamination from anthropogenic 

sources. 

Further, the potable water supply from the Green River may vary by season as it does in 

the Puyallup River causing seasonal variations in arsenic discharged from the WWTP. 

Seasonal monitoring during the four seasons will characterize any variations that may 

occur. The seasonal arsenic monitoring remains as a permit condition. 

As the fact sheet stated the ambient and effluent monitoring will aide in determining if 

the arsenic is naturally occurring or from commercial or industrial origin. 

10. Comment: As part of its Pretreatment Program the City has been conducting bi-annual 

testing and reporting of its influent and effluent for total arsenic concentrations for 10 

years resulting in approximately 140 tests of influent and effluent over this time period. 

Because of the rigorous sampling requirements for low-level analysis, and the time 

required to specially clean and prepare equipment for ‘clean’ sampling per EPA Method 

1669, Puyallup requests that the proposed quarterly sampling be removed from the draft 

permit and replaced with adding inorganic arsenic to the list of pollutants to be tested in 

Part II.A.8., pg. 18 for pretreatment. By doing this six separate samples of both influent 

and effluent will be taken twice annually for five years on three consecutive weekdays 

rather than the four annual samples proposed in the draft permit. 

Response: See Response to Comment 7 Bullet 2 concerning seasonal sampling. The 140 

samples was required by the pretreatment requirements of the permit. That sampling 

requires one sample between January 1 and June 30 and one sample between July 1 and 

December 30. This monitoring frequency is not equivalent to quarterly seasonal sampling.

Bi-annual sampling does not provide the seasonal sampling frequency required to 

characterize the discharges for arsenic. Arsenic varies by season as stated in the Ecology 

Report. “During low flow, mainstem concentrations were 0.76 to 1.0 ug/L. 

Concentrations were lower during high flow – from 0.21 to 0.52 ug/L”

As the fact sheet states the monitoring of the inorganic, dissolved and total arsenic 

coinciding with quarterly ambient will help evaluate partitioning.

To the extent that pretreatment effluent monitoring required in Part II.A.8. satisfies the 

requirement for quarterly arsenic monitoring, these samples may be used to satisfy the 

requirements of Part II.B. Arsenic Monitoring. See Response to Comment 11.

The permit is unchanged. 

11. Comment: The methods used for sampling and analysis are typically dictated by the 

concentration of the analyte or the required sensitivity of the analytical procedure. In the 

case of drinking water, the Safe Drinking Water Act (SDWA) allows as much as 10 μg/L 
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(ppb); whereas, the human health criteria given the consumption of both water and 

aquatic organisms together is 0.018 μg/L (ppb) – a level 555 times lower than the 

SDWA.

The Ecology Report stated the NTR [National Toxic Rule] arsenic criteria are at or below 

the detection limits of routinely available analytical methods 

The water quality concentration of 0.018 μg/L (ppb) requires special clean sampling 

procedures as prescribed by EPA Method 1669 (EPA 1995). Puyallup’s water sampling 

is conducted at a level of care required for a limit of 10 μg/L (ppb) and does not use these 

techniques. Therefore, analytical ‘blips’ are probable. Of 27 potable water sampling 

events conducted 2002 through 2011, only 4 were at the level cited in the Fact Sheet. 

Additionally, Puyallup’s effluent arsenic data, graphed in the Fact Sheet (pg.16) shows a 

maximum concentration below 1.4 μg/L (ppb). Based on 69 influent clean sampling 

episodes conducted since 2003, Puyallup has never reported an influent value exceeding 

2.8 μg/L.

Response:. See Response to Comment 6.

The EPA disagrees that sampling and analytical sensitivity must be at the level of the 

human health standards. The sensitivity must be at a level to detect arsenic concentrations

or at the ML.

Effluent Monitoring

For all effluent arsenic monitoring Puyallup must use sufficiently sensitive analytical 

methods which meet the following:

(i) Use a method that detects and quantifies the level of arsenic, or

(ii) Use a method that can achieve a maximum ML less than or equal to those 

specified in Table 2 Maximum MLs for Pollutants Not Subject to Effluent 

Limitations

Table 2 requires an arsenic ML of 10 μg/L for effluent monitoring. The EPA is requiring 

the most sensitive ML from an EPA approved analytical test method. The most sensitive 

ML is 0.5 μg/L from the approved analytical methods 200.8, Inductively Coupled 

Plasma-Mass Spectrometry (ICP-MS) and 200.9, Graphite Furnace Atomic Absorption, 

for effluent monitoring of total and dissolved arsenic. The ML in Table 2 is changed 

from 10 μg/L to 0.5 μg/L.

The graph on page 16 of the fact sheet shows a minimum arsenic total recoverable 

concentration of 0.6 μg/L. The Comprehensive Non-Conventional Pollutants Effluent 

Sampling , City of Puyallup WPCP submitted with the application reported arsenic levels 

between 0.6 μg/L and 1.3 μg/L, and total recoverable arsenic monitoring by Ecology at 

the Meridian Street Bridge from 2012 and 2013 ranged from 0.51 μg/L to 1.12 μg/L. 

Based on these samples a method with a ML of 0.5 μg/L will detect the minimum 

concentration of total recoverable arsenic.
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The levels of inorganic arsenic concentrations, the speciation of the human health criteria, 

are unknown and must be characterized. The ML remains at 0.036 ug/L.

The requirement to either detect and quantify the concentration or achieve the ML applies 

to all parameters without effluent limitations. Therefore the following Condition replaces 

Condition I.B.7. that restricted monitoring to methods that can achieve MLs for 

parameters without limits. 

Final Condition I.B.7.

“For all effluent monitoring, the permittee must use sufficiently sensitive analytical 

methods which meet the following:

Parameters with an effluent limit. The method must achieve a minimum level (ML) less 

than the effluent limitation unless otherwise specified in Table 1 Effluent Limitations and 

Monitoring Requirements.

Parameters that do not have effluent limitations.

(i) The permittee must use a method that detects and quantifies the level of the 

pollutant, or

(ii) The permittee must use a method that can achieve a maximum ML less than or 

equal to those specified in Table 2 Maximum MLs for Pollutants Not Subject to 

Effluent Limitations;

For parameters that do not have an effluent limit, the permittee may request different 

MLs. The request must be in writing and must be approved by EPA.

See also Part III.D Monitoring Procedures”

Ambient Monitoring

The MDL for ambient total recoverable and dissolved arsenic are 0.5 mg/L. This MDL is 

above the human health standard. The sensitivity must be at a level to detect arsenic 

concentrations or at the MDL.

The draft permit required samples that achieve method detection limits (MDL) that are 

less than or equal to those in Table 3. To further address the comment on detection limits 

at the human health standard Condition I.D.8. is changed to allow the arsenic sampling 

method to achieve either detection and quantification or the MDLs. 

“With the exception of arsenic samples must achieve method detection limits (MDLs) 

that are equivalent to or less than those listed in Table 3. The permittee may request 

different MDLs. The request must be in writing and must be approved by EPA. 
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For arsenic the permittee must use sufficiently sensitive analytical methods which 

detects and quantifies the level of arsenic or a method that can achieve a maximum MDL 

less than or equal to those specified in Table 3.”

In various sections of the Ecology Report and the Fact Sheet based on limited data 

arsenic was reported above the human health standard.

 Total recoverable concentrations range from approximately 0.76 ug/L to over 1.5 

ug/L during low flows as shown on pages 16 and 17 of the fact sheet. 

 The Ecology Report reported ambient arsenic during high flows in the range of

0.21 ug/L to 0.52 ug/L

 The Ecology Report reported for the Puyallup River a mean total receiving water 

arsenic level of 0.71 μg/L and a minimum of 0.47 μg/L well above the human 

health standard (data from August 2001 - August 2006) and for the most part 

above the 0.5 μg/L ML. 

 The Ecology Report reported ambient arsenic during low flows between 0.76 and 

1.0 ug/L.

This limited data indicates arsenic in the Puyallup River is above the human health 

standard. However, this data is limited and insufficient to determine reasonable potential 

to violate the water quality standards for arsenic.

Except during periods of high flow a method with a ML of 0.5 ug/L is capable of 

measuring these concentrations.

The inorganic arsenic concentration in the Puyallup River was found to be 0.40 mg/L

based on one sample. This concentration is also higher then the human health criteria but 

with only one sample insufficient to determine a reasonable potential for human health. 

12. Comment: The draft permit requires total, dissolved, and inorganic arsenic monitoring 

quarterly for five years. In their study, the Department of Ecology typically collected 

samples from the Meridian Street Bridge in Puyallup or by wading into the river or with a 

sample bottle on the end of a polyethylene pole. Samples were primarily taken in spring 

and fall not during the wet season. All soils contain arsenic. Puyallup does not believe 

that an unbiased sample can be collected from the river bank and be guaranteed to be free 

of contamination from the bank itself. And, the only time the river can be safely waded is 

in mid-fall. 

Response: The data provided in the Ecology Report for spring is cited as the “high flow’ 

season sampled using polyethylene poles from shore or by wading and was representative 

of arsenic in the Puyallup River. The City can sample using this method to obtain 

representative samples. 
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The permit requires the City to work with the Puyallup Tribe to establish monitoring 

stations in the Puyallup River. The upstream monitoring station is required to be at a 

minimum distance of 100 feet from the facility’s outfall. Although it would be feasible to 

use the Meridian Street Bridge as it is more than 100 feet upstream from the facility’s 

outfall the City must work with the Puyallup Tribe to establish the monitoring station. 

Further, this monitoring is required by the Tribe’s 401 Certification and must be included 

in the permit under Clean Water Act Section 401(d).

13. Comment: In conclusion, it is unclear how EPA plans on using any collected data. The 

requirements have the potential to subject Puyallup to spurious and costly arsenic 

limitations based on caprice and not based on any realistic expectation that limitations 

will result in any measurable improvement toward meeting human health criteria.

Response: As the fact sheet states the permit requires the Permittee to conduct a limited 

round of inorganic arsenic monitoring to determine whether or not there should be a 

follow up study to determine if arsenic in the treatment plant effluent is naturallyoccurring arsenic, or if it is of commercial or industrial origin.

14. Comment: In Fact Sheet Part X. Other Legal Requirements discussing temperature 

monitoring as a reasonable and prudent measure the fourth paragraph states that 

continuous monitoring of effluent and river upstream monitoring is required. The draft 

permit requires both upstream and downstream monitoring.

Response: The fact sheet contains an error by not including the requirement for 

downstream monitoring. The fact sheet is not enforceable but is an explanation of the 

requirements in the permit. Although the fact sheet does not address downstream 

monitoring the permit does contain the requirement to monitor downstream. Therefore 

the City is required to conduct downstream monitoring.

15. Comment: Appendix C – Basis for Effluent Limitations, Table C-8 Determination of pH 

Limits erroneously uses the acute dilution factor of 1.9 rather than the chronic dilution 

factor of 13.6. The point of compliance with pH is the boundary of the chronic dilution 

zone. The corrected lower pH limit remains unchanged from 6.1 s.u. in the existing 

permit and is not 6.4 s.u. as indicated in the draft permit.

Response: The EPA agrees. The Table below shows at a discharge with a pH of 6.1 s.u. 

the City is within the water quality standard of 6.5. The effluent limitation for pH is 

changed from 6.4 in the draft permit to a final limit of 6.1. This is the same pH effluent 

limit in the previous permit. 
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16. Comment: The information on changes to the ammonia level is incomplete. Two of the 

items we checked appeared to be incorrect:

Appendix D states that 50 ammonia data points were used for ammonia calculations. 

Appendix E contains over 100 dates with ammonia data between August 2003 and 

December 2011. Which dates were used and what is the basis for their selection?

The coefficient of variation (CV) was calculated based on only 50 ammonia data points. 

The CV based on the complete set of data is significantly less than the 1.75 value used 

according to the fact sheet. Puyallup requests that EPA share the spreadsheet files used to 

make the calculations for ammonia Reasonable Potential and Limits.

1. Dilution Factor at Mixing Zone Boundary 13.600

2. Ambient/Upstream/Background Conditions

 Temperature (deg C): 15.90

 pH: 7.70

 Alkalinity (mg CaCO3/L): 20.10

3. Effluent Characteristics

 Temperature (deg C): 23.18

 pH: 6.10

 Alkalinity (mg CaCO3/L): 110.60

1. Ionization Constants

 Upstream/Background pKa: 6.41

 Effluent pKa: 6.36

2. Ionization Fractions

 Upstream/Background Ionization Fraction: 0.95

 Effluent Ionization Fraction: 0.35

3. Total Inorganic Carbon

 Upstream/Background Total Inorganic Carbon (mg CaCO3/L): 21

 Effluent Total Inorganic Carbon (mg CaCO3/L): 312

4. Condtions at Mixing Zone Boundary

 Temperature (deg C): 16.44

 Alkalinity (mg CaCO3/L): 26.75

 Total Inorganic Carbon (mg CaCO3/L): 42.55

 pKa: 6.41

 pH at Mixing Zone Boundary: 6.64

INPUT

OUTPUT

RESULTS

Based on the procedure in EPA's DESCON program (EPA, 1988. Technical Guidance on 

Supplementary Stream Design Conditions for Steady State Modeling. USEPA Office of Water, 

Washington D.C.)
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Response: Reasonable potential and effluent limitations for ammonia were developed 

seasonally. As the fact sheet states the data used are DMR results from August 2003 

through December 2011, there are 50 data points for this period during the months of 

November through April. The calculated CV is 1.754. Appendix D Table D-2 shows 50 

data points used for ammonia for the periods November through April and 52 data points 

for the periods May through October. The total is 102 data points. 

Seasonal Period 

from May through 

October

NH3 mg/L

Seasonal Period 

from November 

through April 

NH3 mg/L

8/31/2003 3.9

9/30/2003 2.3

10/31/2003 2.2

11/30/2003 2.6

12/31/2003 1.1

1/31/2004 2.7

2/29/2004 9.3

3/31/2004 1

4/30/2004 0.6

5/31/2004 0.7

6/30/2004 0.4

7/31/2004 1.3

8/31/2004 2.5

9/30/2004 0.8

10/31/2004 0.4

11/30/2004 0.5

12/31/2004 0.4

1/31/2005 0.8

2/28/2005 0.5

3/31/2005 0.6

4/30/2005 0.6

5/31/2005 0.4

6/30/2005 0.7

7/31/2005 1.6

8/31/2005 0.5

9/30/2005 2.1

10/31/2005 0.5

11/30/2005 0.3

12/31/2005 0.2

1/31/2006 1.8

2/28/2006 0.3
15

3/31/2006 0.3

4/30/2006 0.3

5/31/2006 0.5

6/30/20066

7/31/20062

8/31/2006 0.9

9/30/2006 2.3

10/31/2006 0.2

11/30/2006 1.2

12/31/2006 0.8

1/31/2007 3.9

2/28/2007 0.3

3/31/2007 1.1

4/30/2007 0.9

5/31/2007 0.1

6/30/2007 0.1

7/31/2007 1.4

8/31/2007 1.1

9/30/2007 0.9

10/31/2007 1.6

11/30/2007 0.2

12/31/2007 0.6

1/31/2008 0.2

2/29/2008

0

3/31/2008 0.1

4/30/2008 0.1

5/31/2008 0.1

6/30/2008 0.2

7/31/2008 1.5

8/31/2008 1.3

9/30/2008 0.8

10/31/2008 0.2

11/30/2008 0.2

12/31/2008 0.4

1/31/2009 4.3

2/28/2009 1.7

3/31/2009 0.2

4/30/2009 0.1

5/31/2009 0.1

6/30/2009 0.1

7/31/2009 0.3
16

8/31/2009 1.8

9/30/2009 2.9

10/13/2009 2.9

10/31/2009 1

11/30/2009 0.3

12/31/2009 0.1

1/31/2010 0.3

2/28/2010 0.1

3/31/2010 0.1

4/30/2010 0.1

5/31/2010 0.2

6/30/2010 0.1

7/31/2010 0.7

8/31/2010 1.8

9/30/2010 0.2

10/31/2010 0.4

11/30/2010 0.3

12/31/2010 0.4

1/31/2011 0.2

2/28/2011 0.1

3/31/2011 0.1

4/30/2011 0.2

5/31/2011 2.2

6/30/2011 7.3

7/31/2011 0.3

8/31/2011 0.2

9/30/2011 0.4

10/31/2011 0.6

11/30/2011 0.3

12/31/2011 0.7

Count 52 50

Mean 1.25 0.87

Standard deviation 1.422163 1.522384

CV 1.137731 1.749867

17. Comment: Ammonia limit calculations should be based on Puyallup River pH and 

temperature data pairs, not individual pH and temperature values. It is erroneous to 

assume that the 95th percentile value for pH would occur on the same day as the 95th

percentile for temperature. There is now a substantial amount of river pH and temperature 
17

data that can be used for data pair selection so “limited data” is not a valid argument for 

rejecting this method.

Response: When selecting a reasonable worst-case value for temperature and pH, the 

EPA and states use the percentile value derived from a cumulative frequency distribution 

analysis of a complete data set of pH data and a complete set of temperature. This 

provides more conservative protection for water quality and is more practical than 

attempting to pair pH and temperature.

The Technical Support Document for Toxics Control (EPA, 1996) recognizes the use of 

paired data when extensive data are available. The City is asking for a change from the 

steady state modeling using worse case conditions for pH and temperature with “single, 

constant inputs for effluent flow, effluent concentration, background receiving water 

concentration (RWC)[i.e. ammonia], receiving water flow, and meteorological conditions

(e.g., temperature)” (Section 4.5.1 Wasteload Allocation Methods, page 78). The 

alternative, dynamic modeling, includes more than simply finding pairs. It requires more 

data “using estimates of effluent variability and the variability of receiving water 

assimilation factors to develop effluent requirements in terms of concentration and 

variability. The outputs from dynamic models can be used to base permit limits on 

probability estimates of receiving water concentrations rather than worst-case 

conditions.” “In general, dynamic models account for the daily variations of [i.e. 

temperature and pH] and relationships between flow, effluent, and environmental

conditions and therefore directly determine the actual probability that a water quality 

standards exceedance will occur.” “Dynamic modeling determines an LTA that will be 

adequately protective of the WLA, which relies on actual flow data thereby reducing the 

need to rely on worst case critical flow condition assumptions.”

For example the continuous simulation models have the advantage compared to steadystate formulation of “cross-correlation and interaction of time-varying pH, flow 

temperature, pollutant discharges, and other parameters are incorporated.” However they 

require significantly more data for input information for the application of the time-series 

model.

The TSD lists the Lognormal Probabilistic Dilution Model, Monte Carlo Simulation 

Model and continuous simulation models. The EPA will consider such models submitted 

by the City when data to support them are available. 

The permit is unchanged. 

18. Comment: The ammonia value listed in Appendix E for ammonia on June 20, 2006, is 

5.0 mg/L; however, the actual recorded value was 1.27 mg/L. 

Response: The EPA cannot verify the comment. Changing the June 20, 2006 ammonia 

concentration from 5.0 mg/L to 1.27 mg/L does not change the determination of 

reasonable potential for ammonia for the seasonal period from November through April. 

With the substitution of 1.27 mg/L for 5.0 mg/L the City still has a reasonable potential to 
18

violate the water quality standards from November through April. The permit is 

unchanged. 

19. Comment: The data used to calculate Reasonable Potential for copper needs to be 

clarified. The Reasonable Potential Calculations and Limits calculations contained in 

Table D-2 of the Fact Sheet indicate that 60 samples were used in the calculation. The 

tables in Appendix E, pages 82 – 89 of the Fact Sheet, list 160 effluent values for copper 

from August 2003 through March 2013. Values listed between 8/31/03 and 3/31/08 are 

seemingly listed twice and there is no value listed for 12/31/09 but there are two values 

listed for 1/31/10.

Discounting duplicate entries, there are 116 available data points available on Fact Sheet 

pages 82 – 89. It is not clear which 60 samples were selected or the reason for their 

selection. 

Because the Coefficient of Variation (CV) and the Reasonable Potential Multiplier 

(RPM) are determined from the selected data set, it is important that Puyallup both 

understand and have the opportunity to examine this data used for these calculations prior 

to adoption of the copper limitation.

Because of the selection of data points, differences in calculated values, and the methods 

used are not clear, Puyallup requests that EPA share the spreadsheet files used to make 

the calculations for copper Reasonable Potential and Limits.

Response: The EPA agrees. There are duplicates in the tables for copper on pages 82 

through 89 in Appendix E. Based on the DMRs there are 116 data points between 8/31/03 

and 3/31/08 to calculate the reasonable potential for copper as listed below.

7.2 ug/L 08/31/2003

11. ug/L 09/30/2003

10.6 ug/L 10/31/2003

9.8 ug/L 11/30/2003

10.5 ug/L 12/31/2003

12. ug/L 01/31/2004

9.7 ug/L 02/29/2004

8.1 ug/L 03/31/2004

10.7 ug/L 04/30/2004

10.8 ug/L 05/31/2004

13.4 ug/L 06/30/2004

6.1 ug/L 07/31/2004
19

11.8 ug/L 08/31/2004

. ug/L 09/30/2004

12.2 ug/L 10/31/2004

14.9 ug/L 11/30/2004

13.4 ug/L 12/31/2004

13.8 ug/L 01/31/2005

12.3 ug/L 02/28/2005

15.1 ug/L 03/31/2005

12. ug/L 04/30/2005

9.6 ug/L 05/31/2005

12.5 ug/L 06/30/2005

22.3 ug/L 07/31/2005

16.3 ug/L 08/31/2005

17.4 ug/L 09/30/2005

18.5 ug/L 10/31/2005

. ug/L 11/30/2005

15.6 ug/L 12/31/2005

10.1 ug/L 01/31/2006

13.1 ug/L 02/28/2006

13.2 ug/L 03/31/2006

14.2 ug/L 04/30/2006

16.4 ug/L 05/31/2006

18.4 ug/L 06/30/2006

20.9 ug/L 07/31/2006

14.6 ug/L 08/31/2006

13.8 ug/L 09/30/2006

14.9 ug/L 10/31/2006

17.9 ug/L 11/30/2006

12.4 ug/L 12/31/2006

9. ug/L 01/31/2007

15.5 ug/L 02/28/2007

11.7 ug/L 03/31/2007

12.7 ug/L 04/30/2007

4.5 ug/L 05/31/2007

3.7 ug/L 06/30/2007
20

3. ug/L 07/31/2007

3.1 ug/L 08/31/2007

5.5 ug/L 09/30/2007

6.5 ug/L 10/31/2007

4.2 ug/L 11/30/2007

6. ug/L 12/31/2007

3.9 ug/L 01/31/2008

4.3 ug/L 02/29/2008

5.2 ug/L 03/31/2008

2.8 ug/L 04/30/2008

2.6 ug/L 05/31/2008

2.9 ug/L 06/30/2008

3.4 ug/L 07/31/2008

2.8 ug/L 08/31/2008

2.9 ug/L 09/30/2008

2.8 ug/L 10/31/2008

4.1 ug/L 11/30/2008

4.2 ug/L 12/31/2008

4.3 ug/L 01/31/2009

3.2 ug/L 02/28/2009

2.8 ug/L 03/31/2009

3.7 ug/L 04/30/2009

4.4 ug/L 05/31/2009

3.9 ug/L 06/30/2009

2.6 ug/L 07/31/2009

3.8 ug/L 08/31/2009

4.2 ug/L 09/30/2009

7.7 ug/L 10/31/2009

3.4 ug/L 11/30/2009

5. ug/L 12/31/2009

7.7 ug/L 01/31/2010

5. ug/L 02/28/2010

4.9 ug/L 03/31/2010

7.5 ug/L 04/30/2010

4.4 ug/L 05/31/2010
21

2.7 ug/L 06/30/2010

3.1 ug/L 07/31/2010

3.8 ug/L 08/31/2010

4.2 ug/L 09/30/2010

5.2 ug/L 10/31/2010

6.4 ug/L 11/30/2010

4.9 ug/L 12/31/2010

4.9 ug/L 01/31/2011

4.4 ug/L 02/28/2011

4.8 ug/L 03/31/2011

8.1 ug/L 04/30/2011

6.4 ug/L 05/31/2011

6.3 ug/L 06/30/2011

4. ug/L 07/31/2011

4. ug/L 08/31/2011

3.5 ug/L 09/30/2011

6.7 ug/L 10/31/2011

6.1 ug/L 11/30/2011

5.4 ug/L 12/31/2011

5.9 ug/L 01/31/2012

6.1 ug/L 02/29/2012

5.9 ug/L 03/31/2012

4.8 ug/L 04/30/2012

5. ug/L 05/31/2012

3.4 ug/L 06/30/2012

5.9 ug/L 07/31/2012

5.2 ug/L 08/31/2012

5.2 ug/L 09/30/2012

4.8 ug/L 10/31/2012

4.3 ug/L 11/30/2012

5.6 ug/L 12/31/2012

6. ug/L 01/31/2013

5.9 ug/L 02/28/2013

6.9 ug/L 03/31/2013
22

116. Count

4.829 Standard Deviation

7.751 Average

0.623 CV

22.3 max

Using the 116 data points and using the same spreadsheet and the same equations 

provided in the Technical Support Document the results lead to the same conclusion as is 

in the fact sheet i.e. a reasonable potential to exceed water quality standards was found 

for copper. Using the same procedure as in the fact sheet the resulting limits for copper 

were compared to effluent limits in the previous permit, with the more stringent limits

being selected for the new permit.

The copper CV and RPM are now determined from the same data set from 8/31/03 and 

3/31/08 as provided by the City in their DMRs and stated in the comment. The 

procedures, methods and data set are clear and agree with the City’s proposed data set. 
23

Water Body Type Freshwater Facility: 

Dilution Factors: Acute Chronic

1.9 13.6

13.6

13.6

Nov-April May-Oct Total As AMMONIA, Criteria as Total NH3 AMMONIA, Criteria as Total NH4 ARSENIC (dissolved) 7440382 2 MARSENIC (inorganic)

CADMIUM - 7440439 4M Hardness dependentCHROMIUM(TRI) -16065831 5M Hardness dependentCOPPER - 744058 6M Hardness dependentENDOSULFAN a 959988 11P, b 33213659 12PLEAD - 7439921 7M Dependent on hardness MERCURY 7439976 8MNICKEL - 7440020 9M - Dependent on hardnessSELENIUM 7782492 10M

5 0 5 2 2 6 2 6 2 6 2 3 116 6 102 100 2 6 2 6 

1.75 1.14 0.23 0.23 0.47 0.67 0.623 0.6 0.52 2.34 0.25 0.67 

6 8 6 6 1.38 0.18 2.7 22.3 0.05 1 0.02 3 1.1 

1.1 0.0027 2.4

0.4 0.4 1.03 0.02 0.26 0.94 0 0.05 0.008 0.52 0 

0 0 0.002 0.415

Acute 8 5 140 360 - 1.3266 878.21 6.974 0.22 19.439 2.4 666.25 2 0 

Chronic 1 9 3 1 190 - 0.3355 67.591 3.1707 0.056 0.3838 0.012 47.14 5 

- - - 0.018 - - - 0.93 - 0.14 610 - 

Acute - - 1 - 0.865 - 0.862 - 0.687 0.95 - 

Chronic - - 1 - 0.865 - 0.862 - 0.687 - 0.95 - 

N N Y Y N N N N N N N N 

Aquatic Life Reasonable Potential

1.184 0.913 0.227 0.227 0.447 0.609 0.573 0.555 0.489 1.367 0.246 0.609 

0.912 0.915 0.838 0.838 0.838 0.819 0.961 0.464 0.956 0.955 0.838 0.838 

3.16 2.38 1.36 1.36 1.82 2.37 1.38 3.82 1.36 2.37 1.39 2.26 

Acute 114 8 3 1.473 0.000 0.159 3.489 14.409 0.100 0.514 0.029 2.333 1.310 

Chronic 1 6 1 2 1.092 0.000 0.039 0.711 2.822 0.014 0.115 0.011 0.773 0.183 

YES NO NO n/a NO NO YES NO NO NO NO NO 

Aquatic Life Limit Calculation

4 3 0 3 3 3 3 1 3 3 3 3 3 

1.75 1.14 0.6 0.6 0.6 0.6 0.623 0.6 0.6 0.6 0.6 0.6 

1.75 1.14 0.6 0.6 0.6 0.6 0.623 0.6 0.6 0.6 0.6 0.6 

Acute 161.14 265.7 683.07 - 2.5026 1668.4 12.405 0.418 36.89 4.5528 1265.4 3 8 

Chronic 253.36 416.7 2571 - 4.3113 915.96 31.277 0.7616 4.5899 0.0624 634.56 6 8 

Long Term Averages, ug/L Acute 20.682 48.23 219.32 - 0.8035 535.69 3.8575 0.1342 11.845 1.4618 406.3 12.201 

Chronic 128.8 263.6 1356 - 2.2739 483.11 16.141 0.4017 2.4209 0.0329 334.69 35.865 

20.682 48.23 219.32 0 0.8035 483.11 3.8575 0.1342 2.4209 0.0329 334.69 12.201 

1.00 1.00 1.00 1.00 0.87 1.00 0.86 1.00 0.69 1.00 0.95 1.00 

53.8 66.3 360.6 0.0 1.5 794.2 9.7 0.2 5.8 0.1 579.2 20.1 

161.1 265.7 683.1 0.0 2.9 1504.6 14.4 0.4 11.0 0.1 1097.2 38.0 

Puyal

Receiving Water Data

90th Percentile Conc., ug/L

Geo Mean, ug/L

Human Health Carcinogenic

Human Health Non-Carcinogenic

Aquatic Life

Coeff of Variation (Cv)

Calculated 50th percentile 

Effluent Conc. (when n>10)

Pollutant, CAS No. & 

NPDES Application Ref. No.

Effluent Data

# of Samples (n)

Effluent Concentration, ug/L 

(Max. or 99th Percentile)

Unionized NH3

Aquatic Life Criteria, 

ug/L

Carcinogen?

s

WQ Criteria for Protection of 

Human Health, ug/L

Metal Criteria 

Translator, decimal

Water Quality Criteria

Maximum Daily Limit (MDL), ug/L

# of Compliance Samples Expected per month

Pn

Multiplier

Max concentration (ug/L) at edge of...

Reasonable Potential? Limit Required?

LTA Coeff. Var. (CV), decimal

Permit Limit Coeff. Var. (CV), decimal

Limiting LTA, ug/L

Metal Translator or 1?

Average Monthly Limit (AML), ug/L

Waste Load Allocations, ug/L
24

Calculated Copper 

limits Using 116 data 

points

Copper Limits 

from Previous 

Permit

Limit for New 

Permit

Average Monthly 

Limit (AML)

9.7 ug/L 8.5 ug/L 8.5 ug/L

Maximum Daily Limit 14.4 ug/L 13.7 ug/L 13.7 ug/L

Section 402(o) of the Clean Water Act and federal regulations at 40 CFR §122.44 (l) 

generally prohibit the renewal, reissuance or modification of an existing NPDES permit 

that contains effluent limits, permit conditions or standards that are less stringent than 

those established in the previous permit (i.e., anti-backsliding) but provides limited 

exceptions. Section 402(o)(1) of the CWA states that a permit may not be reissued with 

less-stringent limits established based on Sections 301(b)(1)(C), 303(d) or 303(e) (i.e. 

water quality-based limits or limits established in accordance with State treatment 

standards).

The more stringent copper limits are the limits in the previous permit which the Tribe has 

certified are protective and are therefore retained. 

The permit is unchanged. 

20. Comment: Additionally, we contend that the copper and other metals limitations 

included in the existing permit are premised on erroneous data taken prior to 2002 not 

using ‘clean sampling methods’.

In June 2003, the City concluded a 12 month trace metals study using clean sampling 

methods (Wastewater Treatment Facility Trace Metals Study, February 2004, Gray & 

Osborne No. 02443). This study was presented to EPA and the Puyallup Tribe. Based on 

21 sampling episodes it was found that there was no reasonable potential to exceed lead, 

mercury, and zinc water quality standards. EPA has drawn the same conclusion in the 

draft permit.

More importantly, the coefficient of variation (CV) for copper dropped to 0.29 and the 

limits were recalculated by Puyallup using EPA’s permit level calculation methods. 

Using the new CV value, Puyallup believes its limits should have been established at 11.2 

μg/L for the monthly average rather than the existing 8.5 μg/L. The values indicated on 

page 50 of the Fact Sheet indicate an AML of 10.1 μg/L and a MDL of 14.4 μg/L, 

despite the draft permit limits remaining unchanged from the existing limits.

Following the study, in May 2004 letters were sent to EPA, the Puyallup Tribe, and the 

Department of Ecology asking that limits for lead, mercury, and zinc be removed from 

Puyallup’s permit and that the copper limitation be revised.

When the City failed to receive a response, a letter was sent to Michael Lidgard, NPDES 

Permit Unit Manager, on January 25, 2005, requesting that Puyallup’s permit be 

reopened and revised. The request met the requirements of 40 CFR 124.5 as it was in 
25

writing and contained facts and reasons supporting the request. There was no response to 

this request, as well.

Response: The EPA reevaluated the data as described in response to Comment No. 20 

above. Based on that evaluation, EPA is retaining the existing limits because of 

prohibitions on backsliding. See Response to Comment 19.

21. Comment: EPA now promotes methodologies for determining copper limits that it 

considers improvements over the old EPA hardness-based criteria used to establish 

Puyallup’s copper limitations. Hardness-based criteria is used to establish limitations in 

both Puyallup’s existing permit and its draft permit. The two methods promoted by EPA 

are the Biotic Ligand Model (BLM) for Copper and Streamlined Water-Effects Ratio 

Procedure for Discharges of Copper (EPA -822-R-01-005). 

Puyallup requests that it be permitted to submit a test plan for use of the Biotic Ligand 

Model (BLM) and/or Water-Effects Ratio testing for accurate determination of 

Puyallup’s effluent copper limitation.

Response: Federal regulations at 40 CFR122.44 (vii) states: 

“When developing water quality-based effluent limits under this paragraph the 

permitting authority shall ensure that:

(A)The level of water quality to be achieved by limits on point sources established 

under this paragraph is derived from, and complies with all applicable water quality 

standards;...”

Copper water quality standards derived from a BLM or a water effects ratio are not the 

applicable water quality standards for copper. The applicable water quality standards are 

the current Puyallup Tribes water quality standards for copper. 

Some of the requirements to make BLM and water effects ratio derived copper standards 

applicable to the water quality-based effluent limits in the Puyallup NPDES permit are:

 Revising the Puyallup water quality standards

 Consultation with the U.S. Fish and Wildlife Service (USFWS) on revising the 

Puyallup standards 

 Consultation with the National Marine Fisheries Service (NMFS) on revising the 

Puyallup standards

 EPA approval of the revision

The permit is unchanged. 
26

22. Comment: On December 4, 2013, HDR Engineering, Inc. completed a report reviewing 

different wastewater treatment technologies for their ability to meet discharge limits

associated with revised human health water quality criteria (HHWQC). HDR conducted 

both a literature review of potential technologies and an engineering review of their

capabilities to evaluate and screen treatment methods for meeting revised effluent limits

for four constituents of concern: arsenic, benzo(a)pyrene (BAP), mercury, and

polychlorinated biphenyls (PCBs). Currently, there are no known facilities that treat to the

HHWQC and anticipated effluent limits that are under consideration.

Among numerous other findings, HDR concluded that compliance with a HHWQC for

arsenic of 0.018 μg/L appears unlikely. Most treatment technology performance

information available in the literature is based on drinking water treatment applications

targeting a much higher Safe Drinking Water Act (SDWA) maximum contaminant level

(MCL) of 10 μg/L.

Response: This comment is outside the scope of the reissued permit since the permit 

does not require treatment of arsenic, BAP, mercury or PCBs. 

23. Comment: The 24 hour notification of violation requirement in Condition I.B.2. needs to 

be clarified to address circumstances where analytical results are not immediately 

available. As required in the draft permit, Puyallup may be placed in jeopardy of 

violating this requirement. For example, metals testing, for which there is a maximum 

daily limit, is analyzed for Puyallup by a commercial laboratory and the results are not 

available for two to three weeks after the sample is collected. The results, therefore, are 

not available within 24 hours of violation. Adding language to the draft permit such as 

‘...or within 24 hours of the analytical results being known....’ would correct this 

problem. 

Response: This clarification is already in the permit, violations must be reported when 

the City becomes aware of the circumstances.

Condition I.B.2. states:

“The permittee must report within 24 hours any violation of the maximum daily 

limits for all parameters for which there is a max daily limit in Table 1 above. 

Violations of all other effluent limits are to be reported at the time that discharge 

monitoring reports are submitted (See III.B. and III.H.).”

However, Footnote 2 in Table 1 referring to 24 hour notification of a violation states:

“2. Reporting is required within 24 hours of a maximum daily limit or 

instantaneous maximum limit violation. See Sections I.B.2. and III.G.”

Section III.G. clarifies the 24 hour reporting requirement:
27

G. “Twenty-four Hour Notice of Noncompliance Reporting

1. The permittee must report the following occurrences of noncompliance by 

telephone within 24 hours from the time the permittee becomes aware of 

the circumstances: (emphasis added)

...(d) any violation of a maximum daily discharge limitation for applicable 

pollutants identified in Part I.B.”

The permit is unchanged.

24. Comment: Additionally, because of the challenges associated with the maintenance and 

calibration of continuous monitoring pH instrumentation in a wastewater flow stream 

there is the potential for instantaneous pH excursions, considered Daily Minimum or 

Daily Maximum violations, in the proposed permit. For example, an instantaneous or 

short duration 0.1 pH excursion above or below the minimum or maximum pH limit 

would technically be considered a violation and would need to be reported within 24 

hours. 

We believe it would be prudent and reasonable to place limits on the 24 hour reporting 

requirement in order to mitigate the potential for nuisance ‘emergency’ reporting of 

relatively inconsequential or short-term limit excursions unlikely to have an adverse 

human health or environmental effect. 

Response: Condition I.B.7. requires the use of methods that can achieve a ML less than 

the effluent limitation. This requires the City to maintain and calibrate the continuous pH 

instrumentation to monitor and ensure compliance with the pH limits. Condition I.B.2. 

does not require reporting within 24 hours of pH exceedances, only the toxic pollutants 

copper and ammonia. This is clarified in the final permit.

Federal regulation at § 401.17 pH Effluent limitations under continuous monitoring. 

States:

“(a) Where a permittee continuously measures the pH of wastewater pursuant to a 

requirement or option in a National Pollutant Discharge Elimination System (NPDES)

permit issued pursuant to section 402 of the Act, the permittee shall maintain the pH of 

such wastewater within the range set forth in the applicable effluent limitations 

guidelines, except excursions from the range are permitted subject to the following 

limitations: 

(1) The total time during which the pH values are outside the required range of pH values 

shall not exceed 7 hours and 26 minutes in any calendar month; and 

(2) No individual excursion from the range of pH values shall exceed 60 minutes.”

This exception to excursions are added to the permit. 

Further, as part of the reporting the City may provide information related to 40 CFR 

133.102(c) that states:
28

“(c)pH. The effluent values for pH shall be maintained within the limits of 6.0 to 9.0 

unless the publicly owned treatment works demonstrates that: (1) Inorganic chemicals are 

not added to the waste stream as part of the treatment process; and (2) contributions from 

industrial sources do not cause the pH of the effluent to be less than 6.0 or greater than 

9.0.”

25. Comment: There appears to be an error in the WET testing requirements. In Condition 

I.C.4 the acute toxicity trigger is listed as 1 TUa. This should be 1.9 TUa based on the 

outfall dilution value cited throughout the Fact Sheet. We assume this is an error because 

there is no discussion or justification provided in the fact sheet. If the 1 TUa toxicity 

trigger is not an error, no basis has been provided for this change and therefore we 

request additional time to evaluate the impact of this change.

Also, the draft permit only contains a trigger for accelerated testing for the annual acute 

test. Under the current permit, accelerated chronic testing is required if the annual acute 

test exceeds the acute toxicity threshold.

Response: Permittees are typically only required to perform acute or chronic toxicity 

testing, depending on the dilution available for toxicity. Per EPA guidance at 

EPA/505/2-90-001 at p. 58., acute toxicity testing is recommended when the dilution of 

the effluent is greater than 1000:1 at the edge of the mixing zone, and chronic toxicity 

testing is recommended when the dilution of the effluent falls below 100:1 at the edge of 

the mixing zone. The percentage effluent at the edge of the mixing zone is also referred 

to as the receiving water concentration (RWC). The mixing zone authorized by the 

Washington State Department of Ecology provides for a RWC of 52.6% effluent which is 

1.9:1. Therefore the final permit will only require chronic toxicity testing. Acute toxicity 

testing and the acute toxicity trigger in Condition I.C.4. are deleted from the final permit

and all other references to acute toxicity monitoring is removed from the permit. The 

trigger for accelerated testing in condition I.C.4. is changed to 1.9 TUc. 

26. Comment: Chronic Toxicity – Under Puyallup’s existing permit, accelerated chronic 

toxicity testing is required when the no observable effects threshold (NOEC) exceeds 

11.5 TUc (chronic toxicity units), which is equivalent to chronic toxicity observed in a 

test of diluted effluent at a concentration of 8.7% in river water or synthetic river water. 

This is the concentration at which there can be no effect on the survival, growth, or 

reproduction of the test organisms. 

Under the draft permit there is both a survival endpoint and sublethal endpoints; however, 

there are no requirements listed for the chronic endpoints that would trigger accelerated 

testing. Additionally, the survival endpoint is listed as TUc = 100/NOECm meaning that 

the threshold is exceeded if there is mortality of test organisms in 100% effluent. The 

draft also lists 52.6% effluent as being the dilution associated with the chronic toxicity 

trigger although no subsequent procedure is defined.

Response: The draft permit failed to provide the necessary specificity regarding which 

chronic tests will be required. EPA will revise the final permit to specify that the chronic 
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tests will be the fathead minnow larval survival and growth test (test method 1000.0 in 

EPA-821-R-02—013) and the ceriodaphnia dubia survival and reproduction test (test 

method 1002.0 in EPA-821-R-02-013). These test methods, and their endpoints, are 

identical to the test methods in the previous permit. 

27. Comment: It is not clear whether any additional chronic tests are required under the draft 

permit if accelerated testing is triggered based on the annual acute test results. The 

current permit requires that a toxicity reduction evaluation (TRE) is initiated if an 

accelerated test exceeds a toxicity threshold, and further accelerated testing can end if a 

toxicity identification evaluation (TIE) is also initiated. Under the draft permit, initiation 

of a TRE justifies ending the accelerated testing without the additional requirement of 

initiating a TIE.

Response: Acute testing is not required in the final permit. The toxicity threshold is 

chronic toxicity. The final permit states the permittee may (emphasis added) initiate a TIE 

as part of the overall TRE process. The permit also states if a TIE is initiated prior to 

completion of the accelerated testing, the accelerated testing schedule may be terminated, 

or used as necessary in performing the TIE.

28. Comment: Lastly, toxicity testing is performed for Puyallup by a laboratory 

recommended by the Department of Ecology that specializes in this type of testing. 

Unless the sampling and testing is conducted at the very beginning of a month, the results 

will not be available for submittal with the following month DMR.

Response: Reporting toxicity tests required Condition I.C.6.a) is changed as follows:

The permittee must submit the results of the toxicity tests with the discharge monitoring 

reports (DMR) for the month following sample collection receipt of the results from the 

lab.

29. Comment: The draft requires continuous temperature monitoring 100’ upstream of the 

plant outfall and 302’ downstream, respectively. The center of the outfall diffuser array is 

located about 70’ from the south river bank. To accurately monitor temperature 

representative of the downstream edge of the mixing zone will require placement of a 

downstream monitoring station about 70’ from the south bank. The placement of the 

upstream station is likely less problematic because it does not need to be centered on the 

diffuser array as long as it is 100’ upstream and outside of influence of the diffusers.

 

Because of changes in surface elevation of as much as 20’, significant variations in flow 

between critical flow and extreme storm events, debris carried during storm events, and 

shoulder-to-shoulder fishermen during salmon season, we believe it will be difficult to 

maintain, service, and recover data from the proposed continuous monitoring stations. 

The most practical time to access these locations for monitoring purposes is in the fall 

when the river is typically at its lowest.
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Puyallup is concerned about the time and complexity of meeting this requirement. In the 

absence of detailed guidance on how the City is expected to establish these monitoring 

stations, maintain the recording devices, and collect data from the devices, we 

recommend a monitoring requirement designed around temperature measurements taken 

during the critical flow time of the year when the potential for adverse effects are greatest 

and the ability to access equipment in the river is most practical. 

Response: The Puyallup Tribe’s temperature standard applies for the full year not just 

during low flow periods. The receiving water must be characterized for the year. Data 

loggers have been successful at another location storing a year of temperature data during 

periods when access for recovery was not possible. During this period maintenance of the 

thermistors was not required. For example the TidbiT v2 Water Temperature Data 

Logger - UTBI-001 has a battery life of five years and requires no other service 

according to Onset Hobo Data Loggers, maintains an accuracy of 0.2 oC and has a data 

logger with a capacity 42,900 hours or 4.9 years with the permit required 8,760 data 

points at one hour recording intervals. 

Condition I.D.1. requires the City to work with the Puyallup Tribe to develop a receiving 

water monitoring plan. This plan must include a continuous temperature monitoring plan 

for both effluent temperature monitoring and surface water temperature monitoring. The 

Puyallup Tribe is capable and experienced at providing the necessary guidance on 

locating temperature monitoring stations. The permit is unchanged. 

30. Comment: Part II.D.9. seemingly is a redundant requirement because EPA and the Tribe 

will receive monitoring results throughout the term of the permit per II.D.10. However, 

the language of II.D.10 states that surface water monitoring results must be reported on 

the monthly Discharge Monitoring Report (DMR). DMR’s do not typically have a format 

easily accommodating data that is only submitted quarterly or annually. Puyallup 

recommends that the reporting language in Part I.E.6. of Puyallup’s existing permit be 

retained and replace the language of the draft permit.

Response: Conditions II.D.9. and II.D.10 are not in the permit. However, Conditions 

I.D.9. and I.D.10 are in the permit and refer to submission of monitoring results. 

Condition I.E.6. of the previous permit states:

“Receiving water monitoring results must be submitted to the EPA and the Puyallup 

Tribe Environmental Department with the January Discharge Monitoring Report.”

Condition I.D.9 requires submission of the monitoring reports with the monthly DMRs 

for the EPA to ensure in a timely manner the City is conducting the monitoring without 

waiting until the end of the year. DMRs are used for submission of quarterly results from 

other permittees without problems and will be used without problems for the City’s 

reporting. 

31. Comment: We assume that the required Toxic Organic Sampling under Condition 

II.A.8.i) will satisfy a portion of the required sampling under Part I.B.9, pg. 8, but would 
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like clarification. Additionally, Puyallup requests that language be added ...once during 

the cycle of this permit... for clarification of when and how often the Toxic Organics 

Sampling must be performed during the permit cycle.

Response: The toxic organic sampling requirement in Condition II.A.8.i) of the 

pretreatment requirements can satisfy a portion of the required sampling required under 

Part I.B.9, effluent testing required by Part D of NPDES application Form 2A, which 

states:

“To the extent that effluent monitoring required by other conditions of this permit 

satisfies this requirement, these samples may be used to satisfy the requirements of this 

paragraph.”

Toxic organic sampling is required once per year for the following reasons:

 To characterize the discharges for toxic organic discharges. 

 To determine if a local limit study is needed

 To identify treads in toxic organic discharges and inflow

A toxic organic sampling frequency of once per year is added to the permit. 

32. Comment: The language of Condition II.F. Emergency Response and Public 

Notification Plan is too broad making interpretation difficult and potentially leading to 

the requirement for public notification for events that have little or no health or 

environmental effects. While we feel public notification is a reasonable addition to the 

draft permit, the language needs to be clarified and the notification requirements better 

defined so that it does not result in unnecessary notifications that serve no greater good. 

For example, is the ‘Plan’ only invoked in the event of an unanticipated bypass or 

overflow or is it also invoked at any time any effluent limitation in the permit is exceeded 

as stated in the draft permit? Is the language applicable to instantaneous pH excursions, 

monthly or weekly violations of BOD5, TSS, copper or other such results that may have 

little or no health or environmental effects or in situations where the violation only 

becomes evident after the event has transpired? 

The language of Part II.F. is sensible in the context of a discharge that is immediately 

dangerous to human health or the environment but it does not make sense in the context 

of exceeding “any effluent limitation in the permit...” such as BOD5, TSS, copper or 

other such results that may have little or no health or environmental effects or the 

violation only becomes evident after the event has transpired? 

Response: The plan and public notice is only for “an overflow...that may endanger 

health and unanticipated bypasses or upsets that exceed any effluent limitation in the 

permit.” Public notification is not required any time any effluent limitation in the permit 
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is exceeded, only those that exceed an effluent limitation due to an unanticipated bypass 

or upset or an overflow that may endanger health.

The permit is unchanged. 

33. Comment: Condition III.I., Public Notification reference to Part II.G. is erroneous and 

should reference Part II.F.

Response: The EPA agrees. The reference is changed to Part II.F.