[Federal Register Volume 78, Number 161 (Tuesday, August 20, 2013)]
[Notices]
[Pages 51254-51255]
[FR Doc No: 2013-20202]

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SECURITIES AND EXCHANGE COMMISSION

[Release No. 34-70198; File No. SR-DTC-2013-09]

Self-Regulatory Organizations; The Depository Trust Company;
Notice of Filing and Immediate Effectiveness of Proposed Rule Change To
Eliminate Special Procedures for Securities Offered Pursuant to
Regulation S, Category 3, Under the Securities Act of 1933

August 14, 2013.
    Pursuant to Section 19(b)(1) of the Securities Exchange Act of 1934
(``Act'') \1\ and Rule 19b-4 thereunder,\2\ notice is hereby given that
on July 31, 2013, The Depository Trust Company (``DTC'') filed with the
Securities and Exchange Commission (``Commission'') the proposed rule
change described in Items I, II and III below, which Items have been
prepared primarily by DTC. DTC filed the rule change pursuant to
Section 19(b)(3)(A) \3\ of the Act and Rule 19b-4(f)(4) \4\ thereunder,
so that the proposal was effective upon filing with the Commission. The
Commission is publishing this notice to solicit comments on the rule
change from interested parties.
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    \1\ 15 U.S.C. 78s(b)(1).
    \2\ 17 CFR 240.19b-4.
    \3\ 15 U.S.C. 78s(b)(3)(A).
    \4\ 17 CFR 240.19b-4(f)(4).
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I. Self-Regulatory Organization's Statement of the Terms of Substance
of the Proposed Rule Change

    The purpose of the proposed rule change is to eliminate special
procedures of DTC for securities offered pursuant to Regulation S \5\
(``Reg S''), Category 3, under the Securities Act of 1933 (``Securities
Act'').\6\
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    \5\ 17 CFR 230.901-230.905 and Preliminary Notes.
    \6\ 15 U.S.C. 77a et seq.
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II. Self-Regulatory Organization's Statement of the Purpose of, and
Statutory Basis for, the Proposed Rule Change

    In its filing with the Commission, DTC included statements
concerning the purpose of and basis for the proposed rule change and
discussed any comments it received on the proposed rule change. The
text of these statements may be examined at the places specified in
Item IV below. DTC has prepared summaries, set forth in sections (A),
(B), and (C) below, of the most significant aspects of these
statements.

(A) Self-Regulatory Organization's Statement of the Purpose of, and
Statutory Basis for, the Proposed Rule Change

    (i) DTC's Policy Statement on the Eligibility of Foreign Securities
(the ``Policy'') sets forth the criteria and procedures for making the
securities of foreign issuers (``Foreign Securities'') eligible for
deposit and book-entry transfer through the facilities of DTC.\7\
Foreign Securities eligible for book-entry services include those
offered and sold without registration under the Securities Act
\8\pursuant to Regulation S (``Reg S Securities'').\9\ This includes
Category 1 securities, Category 2 securities, and Category 3 securities
as defined therein (``Category 1, 2, and 3 Securities'',
respectively).\10\ Category 3 of the primary offering safe harbor of
Regulation S includes the equity securities of non-reporting foreign
issuers with substantial U.S. market interest in the subject
securities. In addition to an offshore transaction requirement and
prohibition on directed selling efforts, further requirements might
have to be met to qualify for the first safe harbor. The applicable
requirements depend on the extent to which there is a nexus with the
United States, with more stringent requirements applying the greater
the need is for protection of U.S. investors. The spectrum ranges from
Category 1, where the likelihood of the securities flowing back into
the United States is least, to Category 3, where that likelihood is
greatest.\11\ This rule filing relates to a change in procedures for
Category 3 Securities.
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    \7\ For additional information please see the Policy as set
forth in the DTC Rules. See also SEC Release No. 34-56277 (August
17, 2007), 72 FR 48709 (August 24, 2007) [File No. DR-DTC-2007-04]
for the rule filing implementing the Policy.
    \8\ 15 U.S.C. 77a et seq.
    \9\ Regulation S provides an exemption from the Section 5
registration requirements of the Securities Act of 1933, as amended,
for offerings made outside the United States by both U.S. and
foreign issuers. A securities offering, whether private or public,
made by an issuer outside of the United States in reliance on safe
harbors provided under Regulation S need not be registered under the
Securities Act. See 17 CFR 230.901-230.905 and Preliminary Notes.
    \10\ Category 1 of the primary offering safe harbor of Reg S
includes the securities of foreign issuers for which there is no
substantial U.S. market, securities being offered by foreign (or
domestic) issuers in overseas directed offerings, securities of
foreign governments and securities being offered by foreign issuers
pursuant to employee benefit plans. Category 2 of the primary
offering safe harbor of Reg S includes the equity securities of
reporting foreign issuers, the debt securities of foreign (or
domestic) reporting issuers, and the debt securities of nonreporting
foreign issuers even if there is substantial U.S. market interest in
the securities.
    \11\ See 17 CFR 230.903.
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    Historically, at the request of issuers in consideration of their
own requirements for compliance with applicable law, Category 3
Securities held at DTC have been more tightly controlled than the other
Categories. DTC accordingly required additional documentation from
issuers for chills on deliveries of Category 3 Securities among
Participants for a limited period in connection with the underwriting
distribution of those securities. For the reasons described below, DTC
hereby proposes to eliminate these additional requirements and the
related chills.
    Pursuant to the Policy noted above, Issuers and Participants are
responsible to comply with the Securities Act and the rules and
regulations of the Commission thereunder in any transaction in Foreign
Securities through the facilities of DTC. Additionally, prior to
securities being made eligible at DTC, issuers are required to deliver
a Letter of Representations (``LOR'') to DTC which reflects the
issuer's agreement to comply with the requirements set forth in DTC's
Operational Arrangements (the ``OA'') with respect to securities it has
issued that are held at DTC.\12\ With respect to Reg S Securities, the
LOR also includes a ``Reg S Rider'' with representations of the Issuer
that, at the time of initial issuance, the securities were subject to
applicable transfer restrictions but were eligible for transfer under
Regulation

S.\13\ In addition to the above, the Reg S Rider includes a further
rider for Category 3 Securities (the ``Category 3 Rider''). The
Category 3 Rider reflects the issuer's acknowledgement that the subject
securities will be subject to a ``Deliver Order Chill'' \14\ until DTC
receives a notice from the issuer or agent that the chill should be
removed (except that the chill may be temporarily lifted for certain
transfers relating to depositary banks of certain non-U.S. clearing
entities).\15\
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    \12\ The Operational Arrangements set forth the criteria for
eligibility of securities for DTC services. See www.dtcc.com for a
copy of the OA.
    \13\ Pursuant to its Rules & Procedures (including the OA), DTC
does not in any way undertake, or have any responsibility, to
monitor or ascertain the compliance of any transactions in the
securities with any of the provisions of: (i) Rule 144A; (ii) of
other exemptions from registration under the Securities Act or any
other state or federal securities laws; or (iii) of offering
documents. The Reg S Rider provides for the issuer's acknowledgement
of DTC's role in this regard.
    \14\ A chill imposed by DTC automatically prevents processing of
certain transactions among Participants.
    \15\ Specifically, the chill does not encompass deliveries via
DTC's Deposit/Withdrawal at Custodian (DWAC) system in Participant
accounts maintained by banks that act as depositaries for
Clearstream S.A. and Euroclear.
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    The Category 3 Rider is a redundant statement of issuer's
obligations under the applicable securities laws and DTC's Rules &
Procedures and is generally no longer used efficiently or effectively
by Issuers. Further, DTC is not responsible for issuer and Participant
compliance with Reg S and is unable to determine whether the Category 3
chill is properly imposed or lifted. Also, the existence of a chill
relating to the Category 3 Rider may preclude timely deliveries among
Participants. For these reasons, DTC proposes to delete the Category 3
Rider to the Reg S LOR and to eliminate Category 3 Deliver Order
Chills. As a conforming change to the OA, DTC will delete any reference
to the Category 3 Reg S Rider.
    (ii) The proposed rule change is consistent with the requirements
of Section 17A(b)(3)(F) \16\ of the Securities Exchange Act of 1934, as
amended (the ``Act''), and the rules and regulations thereunder
applicable to DTC as it is designed to promote the prompt and accurate
clearance and settlement of securities transactions. The rule filing
will harmonize DTC's processes across Categories of Reg S Securities,
reduce costs and operational burden associated with the imposition and
lifting of Deliver Order Chills by DTC, and promote efficiency with
respect to deliveries of affected securities, as applicable.
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    \16\ 15 U.S.C. 78q-1(b)(3)(F).
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(B) Self-Regulatory Organization's Statement on Burden on Competition

    DTC does not believe that the proposed rule change will have any
impact, or impose any burden, on competition since it relates solely to
the elimination of a redundant procedure, which may create a processing
burden for DTC, Participants, and issuers.

(C) Self-Regulatory Organization's Statement on Comments on the
Proposed Rule Change Received From Members, Participants, or Others

    Written comments relating to the proposed rule change have not been
solicited or received. DTC will notify the Commission of any written
comments received by DTC.

III. Date of Effectiveness of the Proposed Rule Change and Timing for
Commission Action

    The foregoing rule change will become effective pursuant to Section
19(b)(3)(A) \17\ of the Act and paragraph (f)(4) of Rule 19b-4 \18\
thereunder on a date to be announced by DTC via Important Notice. At
any time within 60 days of the filing of the proposed rule change, the
Commission summarily may temporarily suspend such rule change if it
appears to the Commission that such action is necessary or appropriate
in the public interest, for the protection of investors, or otherwise
in furtherance of the purposes of the Act.
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    \17\ 15 U.S.C. 78s(b)(3)(A).
    \18\ 17 CFR 240.19b-4(f)(4).
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IV. Solicitation of Comments

    Interested persons are invited to submit written data, views, and
arguments concerning the foregoing, including whether the proposed rule
change is consistent with the Act. Comments may be submitted by any of
the following methods:

Electronic Comments

     Use the Commission's Internet comment form (http://www.sec.gov/rules/sro.shtml); or
     Send an email to<EMAIL_ADDRESS>Please include
File Number SR-DTC-2013-09 on the subject line.

Paper Comments

     Send paper comments in triplicate to Elizabeth M. Murphy,
Secretary, Securities and Exchange Commission, 100 F Street NE.,
Washington, DC 20549-1090.

All submissions should refer to File Number SR-DTC-2013-09. This file
number should be included on the subject line if email is used. To help
the Commission process and review your comments more efficiently,
please use only one method. The Commission will post all comments on
the Commission's Internet Web site (http://www.sec.gov/rules/sro.shtml). Copies of the submission, all subsequent amendments, all
written statements with respect to the proposed rule change that are
filed with the Commission, and all written communications relating to
the proposed rule change between the Commission and any person, other
than those that may be withheld from the public in accordance with the
provisions of 5 U.S.C. 552, will be available for Web site viewing and
printing in the Commission's Public Reference Room, 100 F Street NE.,
Washington, DC 20549, on official business days between the hours of
10:00 a.m. and 3:00 p.m. Copies of such filings also will be available
for inspection and copying at the principal office of DTC. All comments
received will be posted without change; the Commission does not edit
personal identifying information from submissions.

    You should submit only information that you wish to make available
publicly. All submissions should refer to File Number SR-DTC-2013-09
and should be submitted on or before September 10, 2013.

    For the Commission by the Division of Trading and Markets,
pursuant to delegated authority.\19\
Kevin M. O'Neill,
Deputy Secretary.
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    \19\ 17 CFR 200.30-3(a)(12).
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[FR Doc. 2013-20202 Filed 8-19-13; 8:45 am]
BILLING CODE 8011-01-P


B 1 State of Oregon Department of Environmental Quality Memorandum Date: 4/ 16/ 98 To: File From: Bob Baumgartner Subject: Columbia Slough Winter Dissolved Oxygen Analysis Background: The Columbia Slough is water quality limited ( WQL) for dissolved oxygen. Pulses of low dissolved oxygen concentrations are associated with deicing events at the Port of Portland international airport ( PDX).

The federal Clean Water Act requires that pollution control plans defined as Total Maximum Daily Loads ( TMDLs) be established for WQL limited streams. The federal Clean Water Act requires TMDLs to be established with existing data, include a reasonable margin of safety to cover uncertainty with existing knowledge, establish a load for background where possible, and allow for future growth and development.

The TMDL for dissolved oxygen defines separate loading capacities ( LC) which varies with stream flow and the dissolved oxygen criteria applied. In order to establish allocations that reflect the pulses of storm driven events the LC also varies by the duration of the low dissolved oxygen events. The State dissolved oxygen criteria varies in relationship to the duration of the low oxygen event. The instantaneous instream DO should not fall below 4 mg/ l, the seven ( 7) day average of the daily minimums should not fall below 5 mg/ l, and the lowest thirty ( 30) day average of the daily means should not fall below 6.5 mg/ l.

The loading capacity ( LC) and margin of safety ( MOS) are estimated using both existing field data and available literature. This memorandum summarizes the available information that was used to identify the loading capacity and subsequent allocations. The approach used, as are all models, is a simplification of reality. The discharges are assumed to be plug flows. The available data and literature were used to select reasonable model inputs. Field conditions were selected to represent likely worst case scenarios.

The TMDL distributes allocations to the three ( 3) defined sources; de icing loads, storm water loads, and background. The storm water load is further subdivided between loads regulated by the designated management agencies and permitted industrial storm water.

AMBIENT DATA:

The Columbia Slough is listed as being WQL based on observation of substandard dissolved oxygen. The instream dissolved oxygen is influenced in part by the instream BOD5 concentrations. Temperature directly influences the dissolved oxygen concentration by establishing the level of saturation and indirectly by controlling the rate of reactions that influence B 2 dissolved oxygen levels. Much of the ambient data is available in a series of documents and memoranda published by Portland State University ( PSU) and supported by the City of Portland ( Wells( 1992), Wells and Berger ( 1995) Wells et al ( 1996)). Much of this information is also reviewed and presented in the Columbia Slough Water Body Assessment ( CH2MHill 1995) conducted for the City of Portland. Ambient data is available from the City of Portland and from DEQ.

Ambient Dissolved Oxygen Data: Substantial review of historical dissolved oxygen data is contained in the Water Body Assessment ( CH2MHill 1995).

Field data for dissolved oxygen can be reviewed to determine the magnitude of the DO problems. Comparison of the ambient conditions associated with depressed oxygen can be used to define the conditions that result in the low oxygen.

Critical conditions for low dissolved oxygen appear to occur following freezing weather, followed by warm rain with increasing temperature in the receiving stream. In the Lower Columbia Slough increasing stage from the Willamette appears to be associated with depressed oxygen. This is likely due to increased residence time and reduced aeration.

Several periods of low dissolved oxygen have been observed in both the Lower and Upper Columbia Slough. Continuous monitoring data collected by the City of Portland is the most robust record of the low DO occurrences. Some ancillary data may also be recorded, however, coincident instream BOD data is sparse. Low dissolved oxygen data have been observed and associated with de icing events for several years. This data is summarized in Table 1.

The February 1995 low DO event in the Lower Slough occurred following a cold period when instream temperatures increased and river stage increased due to high water in the Willamette River. Increasing stream temperatures also occurred at MCDD1 during the event.

Wells and Berger ( 1996) discuss the two ( 2) significant low dissolved oxygen events observed during late 1995, early 1996. The events occurred following cold periods followed by rain. Figure 1 shows the decreasing instream DO levels as the instream temperature began to rise. Table 1, Dissolved Oxygen Data Lower Columbia Slough Date DO Location of DO Load Estimate High BOD 1/ 10 25/ 95 1 SJB 2/ 4 9/ 95 < 5 SJB 2/ 19 24/ 95 0 SJB 2/ 21/ 95 0 Landfill 12/ 10/ 95 0 N. Denver 1/ 28/ 96 > 4 N. Denver 1/ 18/ 96 2/ 10/ 96 0 N. Denver 2/ 4 5/ 96 2/ 15/ 96 4 SJB 2/ 4  5/ 96 12/ 30/ 96 > 1 N. Denver 78 Upper Columbia Slough 1/ 15 25/ 95 > 4 2 MCDD1 2/ 5 19,95 > 5> 4 MCDD1 75 11/ 16/ 95 > 5 MCDD1 1/ 28/ 96 > 2 MCDD1 1/ 18 30/ 96 2/ 3 4/ 96 > 1 MCDD1 2/ 4 5/ 96 B 3 Instream conditions are characterized by warming stream temperatures and stagnation in the Lower Slough due to increased stage because of high water in the Willamette. The low DO events lasted from 5 to 10 days in the Lower Slough. No oxygen sag was observed at stations upstream of the airport discharge. Similar physical conditions and low dissolved oxygen were observed in December 1996 January 1997. Continuous data recorded in December 1996 January 1997 shows the dissolved oxygen sag becoming apparent at RM 6.9 as early as 12/ 27 28. At N. Denver Bridge the minimum dissolved oxygen of 0.99 mg/ L occurred at 2100 hours at 12/ 30/ 96 and recovery began by the end of the day, 12/ 31. Near RM 2.9 the minimum DO occurred near 0500 on 1/ 4/ 97, several days later than when peak BOD5 measures were recorded. However, BOD5 concentrations would also be reduced by degradation rates. The plug of low DO occurred about 4.3125 days later at RM 2.9. The average velocity was estimated as the difference in time from minimum DO divided by distance ( 3.8 miles/ 4.3 days) as 0.054 f/ s, similar to the velocities estimated using observed BOD5 data. Observed stream temperature near 5.2 C had begun to increase by the time the minimum DO was recorded at RM 6.7 Stream temperatures had increased substantially to near 7.1 C by the time the minimum DO was recorded near RM 2.9. Willamette River stage was near 10.3 feet during this period.

Previous storm monitoring in the Slough did not suggest reduced dissolved oxygen associated with storm water discharge ( City of Portland BES, 1989). There were three storm event monitoring efforts conducted by the City of Portland on May 22, April 21 and May 2, 1988. The dissolved oxygen during these events was not reduced to near water quality standards during these surveys.

Occasional periods of reduced oxygen are apparent in the field data that are not known to be associated with de icing events. This field data would suggest conditions other than de icing influence ambient dissolved oxygen levels. Simulations presented by Wells and Berger ( 1995) indicate oxygen reduction during storm events to near the dissolved oxygen standard after the estimated de icing load was eliminated. The simulations suggests that storm water and CSOs may reduce dissolved oxygen in the Slough, however, the storm water induced reduction of dissolved oxygen is not well defined with existing data.

Ambient BOD measures: Ambient BOD concentration is the result of natural background contribution, source loading of BOD, and decay. Where information of source loads and background are known or can be reasonably approximated, ambient measures of BOD can be compared to estimates of loading and dilution to determine if such estimates appear to reasonably explain the observed conditions. Where associated with hydraulics data, observed changes in ambient BOD concentration may be used to estimate instream decay rates. Dissolved Oxygen and Temperature in the Lower slough following De icing 0 2 4 6 8 10 16 Dec 21 Dec 26 Dec 31 Dec 5 Jan 10 Jan Date mg/ l , C Temp. at NDB Temp. SJB DO at NDB DO at SJB Figure 1, Dissolved Oxygen and Temperature in the Lower Slough B 4 Instream BOD5 concentrations reported by the City Portland vary from greater than detection to below detection ( Nancy Hendricksen, BES, personnel communication) ( Figure 2). Maximum recorded concentrations are 75 mg/ l BOD5 . Well defined spatial trends are not apparent in the data provided by the City of Portland. Using the existing information the estimated mean BOD5 concentration in the Columbia Slough is 2.5 mg/ l BOD5 A maximum instream BOD of 150 mg/ l is presented graphically as BODu by Wells and Berger ( 1995) for the Columbia Slough near Alderwood. Measured BOD5 of > 70 mg/ l is illustrated for near MCDD4, and > 60 mg/ l near NE Alderwood in February 1995. During deicing events in 1995 1996 the observed oxygen demand concentrations reported by the City of Portland frequently exceed the maximum reporting level of 20 mg/ l BOD5 ( Nancy Hendricksen, personnel communication).

Similar elevated levels of BOD5 (  80 mg/ L) are reported by the City of Portland during a December 1996/ January 1997 event. Instream data were collected by the City of Portland to evaluate the pulses of low DO from de icing events. This data demonstrates that pulses of high BOD periodically move through the Columbia Slough. The timing and concentrations of the peak BOD5 at different locations may be used to calculate deoxygenation rates and travel times. The peak BOD5 concentration data drops from > 78 to 52 mg/ l between river miles 6.7 and 1.2 ( Figure 3). The peak BOD5 concentration occurred several ( 1.9 2.8) days later at river mile 1.2 than at river mile 6.7. The difference in peak concentrations suggest relatively slow velocities ( 0.08  0.12 f/ s). Relatively high ( 0.14 0.20 / day) BOD5 loss rates ( Kr) may be estimated by solving for Kr using: BOD BOD e rm RM K X v r 1 2 6 7 . . = . However the peak BOD5 data near river mile 1.2 is potentially influenced by dilution from the Willamette and dispersion. Instream BOD5 data suggest that peak concentrations near RM 6.7 were missed by the ambient monitoring. Similarly the peak BOD5 concentrations near RM 1.2 are not known. The BOD5 concentrations near river mile 2.9 suggest a plug of BOD5 on the order of four ( 4) days passed through the Lower Slough. This observation is consistent with the general length of the DO sag observed near Denver Bridge.

Ambient Temperature: Cursory observation of available data indicates stream temperatures were near 5C as measured at St. Johns Bridge at the initiation of the February 1995 de icing event ( Wells et al 1996). Over the next several days the dissolved oxygen dropped to anoxic conditions and the temperature increased to approximately 10C. A similar increase in temperature through the low dissolved oxygen event was observed during January 1997. Similarly, at MCDD1 the dissolved oxygen generally drops as temperature increases. Minimum temperatures were near 4C. Reduced Instream BOD, City of Portland, All station y =  0.8397x + 0.9395 R2 = 0.9626  2  1 0 1 2 3 4 5  4  3  2  1 0 1 2 3 4 Z Log( n) BOD Figure 2, BOD Distribution Columbia Slough BOD( 5)

0 10 20 30 40 50 60 70 80 12/ 30/ 96 12/ 31/ 96 1/ 1/ 97 1/ 2/ 97 1/ 3/ 97 1/ 4/ 97 Date mg/ l RM 6.7 RM 2.9 Figure 3, BOD by date and location B 5 dissolved oxygen conditions occurred at temperatures in the range of 7.5C to 12C. Continuous monitoring data was collected by the City of Portland between Julian Day 27 and 70 ( figure 25 Wells and Berger) in the Upper and Lower Slough. This data shows that the dissolved oxygen depressions observed occurred during periods where temperature was near 9C in the Lower Slough ( St. Johns Bridge) and near 8C in the Upper Slough ( MCDD1)

Willamette River stage: The stage of the Willamette river can substantially influence how fast water moves through the Lower Columbia Slough. As stage increases, water backs up into the Columbia Slough, resulting in reduced velocity, longer residence time ( stagnation) and reduced calculated aeration rates ( Wells and Berger 1995). The Willamette river stage frequently exceeded 15 feet MSL and occasionally exceeded 20 feet MSL during the winter 1996/ 97. The 12 day averages, estimated to be the residence time of water in the Slough at high stage and low flow, frequently approached or exceeded a stage of 15 feet MSL ( see Figure 4). The City of Portland ( 1989) reports that stage levels in the Columbia Slough of 14 to 17 feet are routinely reached.

RATES: Estimates of the loading capacity of the Columbia Slough are dependent upon estimates of the rates of reaction. The principle rates that influence dissolved oxygen in this analysis are the rate at which deoxygenation ( Kd) occurs from BOD and the rate of oxygen brought back into the Slough from aeration ( Ka). Temperature influences both of these rates and so is important in estimating the loading capacity. The dispersion rate ( Ex) can also significantly influence the loading capacity for the short term pulse loads of oxygen demand.

Calculation of Biochemical Deoxygenation ( decay) Rate ( kd) Estimates of Kd were derived from UBOD/ BOD5 information presented in the Final Evaluation of Alternatives for controlling the Environmental Impacts of De icing, LTI CH2M Hill, 4/ 29/ 1996 ( deicing study) and from percent theoretical oxygen demand at five days information provided by Union Carbide Corporation as part of information provided during public hearings. The Union Carbide data showed that most of the theoretical oxygen demand was consumed within 20 days. The theoretical oxygen demand therefore provides a reasonable estimate of the UBOD. Kd was calculated by two methods; a simple method based on the mathematical relationship between BODu and BOD5, and a least squared regression analysis of the data. The following section discusses both methods.

In table 2.4 of the de icing study, values from five day ( CBOD5) and Ultimate ( CBODu) were provided for both propylene and ethylene glycol and from Type 1 and Type 2 aircraft de icing fluids. Knowing the CBOD5 and BODu the Kd rate was calculated as: K Log BOD BOD T d n U =    ( ) 1 5 . Daily and 12 day average stage 0 5 10 15 20 25 30 9/ 8/ 95 10/ 28/ 95 12/ 17/ 95 2/ 5/ 96 3/ 26/ 96 5/ 15/ 96 7/ 4/ 96 Date MSL Stage 12 D avg Figure 4, Daily and 12 day average stage B 6 The Kd values calculated from the various data reported varied from 0.05/ day to 0.24/ day with a median of 0.143/ day and a standard deviation of 0.06. The rates were presumed to be measured at 20C. The calculated deoxygenation rates are similar to the range of 0.1/ day  0.2/ day at 20 C used by Wells and Berger ( 1995) in their modeling efforts, and are similar to and slightly less than estimated from limited instream data collected during December 1996, January 1997.

Biochemical deoxygenation rates expressed as a percentage of the theoretical oxygen demand were presented by Union Carbide for three ( 3) temperature ranges of 4, 10, and 20C for both ethylene and propylene glycol. The Kd was calculated by empirical regression of Log BOD BOD vs T n t u ( ).. 1  The slope of the regression provides a measure of the Kd. As seen in Figure 5, for propylene glycol, Kd was calculated to be 0.127 for data presented at 20 C.

Cursory observation of the raw data indicates that there is a considerable lag phase in the deoxygenation tests, especially at the 4C temperature test. Derivation of kd using the regression equation appears to be less influenced by the lag than would similar derivation using the simple calculations. The observed lag phase could result in an underestimation of the decay rate once the bacterial population was established. For ethylene glycol the observed Kd was 0.043/ day using all data ( Figure 6). Presuming that any lag phase was complete within 10 days a higher Kd of 0.049/ day was derived. Partially acclimated bacteria were used in the original tests.

To model the loading capacity of BOD, the median Kd of 0.143 at 20C was used. Empirical Derivation of Decay Rates for Propylene glycol at 20C y =  0.1274x  0.0834  3  2.5  2  1.5  1  0.5 0 0 5 10 15 20 Time ( days) LN( 1

BODt/ UBOD)

Figure 5, regression analysis for propylene glycol Kd for Ethylene Glycol at 4C y =  0.0428x + 0.129 R2 = 0.9668  1.5  1  0.5 0 0.5 0 10 20 30 40 Days Figure 6, regression analysis for ethylene glycol B 7 Influence of Temperature on Kd Reports provided by Union Carbide contained deoxygenation data for three temperature ranges. Observed Kd was derived for each of the three temperatures ( 4, 10, 20C) included in the study. The influence of temperature on Kd was expressed as theta where: K K d d t t =

20 20  ( ) and calculated directly as: K K t t 20 1 20   =   for each temperature ( 10, 4 C).

The decay rates were calculated as a percentage of the theoretical oxygen demand. The decay rates appear consistent with those reported earlier. The regression ( Reg) rates were described above, the simple rates are the median values of the Kd determined independently for each temperature. The influence of temperature expressed as theta has a median value of 1.102 and a standard deviation of 0.027. These results are summarized in Table 2.

The calculated theta is within the upper range of values typically used for carbonaceous BOD originating from municipal wastewater treatment plants ( Thomann and Mueller 1991 = 1.04, Tchoboanogolous and Schroeder ( 1985) ( 1.135 in Wells and Berger 1995). The influence on temperature is similar to that used by Wells and Berger in their modeling efforts. The formulation used by Wells and Berger would reduce deoxygenation rates more severely below 6 C, and less severely above 6 C than the calculated theta of 1.1.

A theta value of 1.10 is used in the loading capacity modeling.

Calculation of Aeration Rate ( Ka): A variety of aeration rates have been suggested for use in the Columbia Slough model. PDX presented Ka in the range of 3.1 4.0/ day from field data collected in April 1996. The field data was interpreted to suggest that the aeration rates used by Wells and Berger of less than 1/ day may underestimate aeration. The wide discrepancy may reflect the variability that could be observed in the Columbia Slough system. Aeration rates are often expressed as a mathematical function of stream depth and velocity. Both velocity and depth vary independent of flow in the Columbia Slough.

Lower Slough aeration rates: In the Lower Slough, during the winter, the stream depth is often controlled by the river stage of the Willamette and Columbia Rivers. When the Willamette river stage is high, water backs up into the Columbia Slough resulting in reduced advective flow out of the Slough. Cursory observation of available continuous monitoring data suggest that critically low dissolved oxygen levels ( anoxic) are associated with high river stage. During the 1995 oxygen depletion event the Table 2, Calculated decay rates and theta Propylene Ethylene T Reg Simple Reg Simple 20 0.127 0.138 0.188 0.151 10 0.066 0.067 0.066 0.055 4 0.053 0.026 0.042 0.028 Theta 10 1.07 1.07 1.11 1.11 4 1.06 1.11 1.09 1.11 B 8 river stage increased from near 6 ft MSL to 13 feet MSL. Aeration rates have not been measured during the periods of critically low dissolved oxygen.

Aeration rates were initially estimated using an O'Connor Dobbins equation ( K u h a = 12 9 1 2 3 2 . ).

Stream velocity ( u) was estimated using generalized stream cross section data and discharge. Results were compared to detention time nomographs presented by Wells and Berger ( 1995). Velocity estimates using generalized stream physical conditions are similar to the velocities estimated using continuous monitoring data collected in December 1996 January 1997 of 0.05 to 0.12 f/ s at relatively high stage ( 5 15 MSL) and discharges of less than 250 cfs ( Figure 7).

Depth ( h) was estimated as the difference between bottom elevations reported by Wells and Berger ( 1995) and stage. As seen in Figure 8 and Table 3, the resulting estimates of aeration suggest that at the annual high stream stages typically observed of > 15ft MSL, the aeration rates would be substantially lower than at a more typical summer low flow range of 6 feet MSL.

5 7 9 11 13 15 50 100 150 200 250 300 0 0.2 0.4 0.6 0.8 1 1.2 Surface MSL Calculated Ka ( Occonner Dobbins) Using Surface Water MSL and Discharge for the lower Columbia Slough 1 1.2 0.8 1 0.6 0.8 0.4 0.6 0.2 0.4 0 0.2 Figure 8, Ka, Discharge, Stage Wind induced aeration may become an important contributor to the oxygen balance under conditions of high stage and low velocity.

Upper Slough aeration rates: Stream stage in the Upper Slough is regulated for flood control and stream depth is not necessarily a function of discharge. In the Upper Slough the stage is not directly related to the Willamette River stage. Aeration rates were estimated using generalized stream geometry data and discharge ( Figure 9). Results were compared to detention time data presented by Wells and Berger ( 1995). The generalized aeration rates may approximate averaged conditions, they will not represent specific locations. The Upper Slough is deeper and wider near MCDD1 resulting in reduced aeration rates compared to the estimated aeration rates for the rest of the Upper Slough 5 7 9 11 13 15 50 100 150 200 250 300 0 0.1 0.2 0.3 0.4 0.5 0.6 f/ s MSL Estimate Velocity by Stage and Discharge 0.5 0.6 0.4 0.5 0.3 0.4 0.2 0.3 0.1 0.2 0 0.1 Figure 7, Stage, Discharge, Velocity cfs/ MS L 5 10 15 20 100 0.65 0.13 0.06 0.03 200 0.98 0.19 9 0.08 0.05 300 1.16 0.23 0.10 0.06 Table 3: Lower Slough Est. Ka B 9 ( Table 4). The observed dissolved oxygen sags near MCDD1 may be a function of the lower aeration rates. The estimated aeration rates for the Upper Slough can exceed those estimated for the Lower Slough. Similar to the Lower Slough the aeration rates are much lower at a relatively high stage MSL of 8 feet as compared to a MSL of 6 feet. Estimated Ka is much lower at MCDD1.

Effect of wind on aeration rates: The equation used to calculate aeration is appropriate for moderately deep to deep channels ( 1ft < H < 30 ft) with velocities in the range of 0.5 fps < U < 1.6 fps ( EPA Technical Guidance Manual for Performing Waste Load Allocations, 1992). Velocities for the Columbia Slough, during critical time periods, range from 0.05 fps to 0.12 fps. Using the O'Connor Dobbins formula may underestimate the aeration rate, as Ka approaches zero as the depth increases. For these two reasons, the O'Connor  Dobbins formula may be inappropriate for the Columbia Slough.

Due to low velocities, with deep and stagnant waters, the Columbia Slough system is similar to a lake. DEQ evaluated equations for calculating gas transfer rates ( KL) and Ka for lakes and reservoirs. In such waterbodies the effect of wind on reaertion may be significant. Banks and Herrera ( Thomann and Mueller, 1987) suggest the following equation to estimate KL.

K U U U L w w w =   + 0 728 0 317 0 0372 1 2 2 . . .

where U is wind speed in m/ s and KL is the wind driven oxygen transfer coefficient in m/ day.

To determine an appropriate KL for the aeration calculations, wind data, Willamette River stage data and Columbia Slough DO data were evaluated for time periods when DO levels dropped to anoxic conditions. Using hourly average wind speed for the period of February 15 22, 1995, values for KL were calculated using the Banks and Herrera equation. A minimum daily average KL which represented the critical conditions was estimated. A minimum daily average Ka ( reaeration coefficient) was calculated using the following equation:

K K H a L = / where H is depth of the waterbody.

Effect of temperature on Ka: 6 8 10 50 100 300 0 0.5 1 1.5 2 2.5 3 3.5 4 Ka MSL Q Upper Slough Aeration ( O'Conner Dobbins)

Figure 9, Ka, Stage, Discharge Upper Slough At MCDD 1 cfs/ M SL 6 8 10 6 8 10 50 1.6 0.6 0.3 0.09 0.06 0.04 100 2.3 0.8 0.4 0.12 0.08 0.06 300 3.9 1.4 0.7 0.21 0.15 0.10 Table 4: Ka generalized for the upper Slough and for MCDD1 B 10 The reaeration coefficient was adjusted for temperature ( at 8 ° C) using the following equation: K K a a t t =

20 20  ( )

No specific information is available for estimating the influence of temperature on aeration rates. The standard default theta of 1.024 ( USEPA) is recommended. The minimum daily average KL was estimated as 0.577 m/ day and the minimum daily average Ka was estimated as 0.107 at 8 ° C.

Effect of dispersion on instream BOD: In any river, there is mixing that occurs along the river due to horizontal and vertical gradients in velocity. This phenomenon is known as longitudinal dispersion, and preliminary calculations indicate that peak downstream BOD concentrations will be reduced if dispersion is considered in the dissolved oxygen analysis. The Port of Portland calculated dispersion coefficients ( Ex) from reaeration studies conducted during April, 1996. Ex was estimated to be 2.3 ft2/ sec and 26.8 ft2/ sec, at flow rates in the Upper Slough of 50 cfs and 75 cfs, respectively. The pumping rates at MCDD1 were assumed to be 75 cfs and 300 cfs, respectively. DEQ estimated Ex using the following equation ( Thomann, 1987):

E U B HU x =   34 10 5 2 2 . ( ) * where U is the mean velocity in fps, B is the mean width in feet, H is the mean depth in feet, and U* is the shear velocity in fps.

Estimates of Ex obtained by this method were of the same order of magnitude for each selected flow as those calculated by the Port of Portland. DEQ used Ex values of 2.0 ft2/ sec for 100 cfs and 20 ft2/ sec for both 200 cfs and 300 cfs.

Results of sensitivity analyses demonstrate that dispersion affects the peak instream BOD values for short term discharges (< 1.5 days). During short discharge periods, the BOD load acts as a plug moving through the Slough. Increasing the discharge period results in the Port's discharge acting as a continuous discharge, with dispersion becoming insignificant. To simplify the analysis, the time of the Port's discharge is limited to one day.

Time to critical deficit : The dissolved oxygen reaches a maximum deficit at a " critical time" when the uptake of oxygen by the BOD is balanced by input of oxygen from the air: t K K Log K K D K K K L c a d n a d a d d * ( { ( ) } =       1 1 0 0 , where D0 is the initial oxygen deficit and Lo is the initial BODu. Under current conditions the Columbia Slough becomes so heavily loaded with organic material that oxygen will approach depletion, and anaerobic conditions will result. The start of the anaerobic condition occurs prior to the point where critical oxygen deficit would occur. Assuming no other sources, the point of recovery from anaerobic conditions will be dependent upon the aeration rates. Under the anaerobic conditions the rate of BOD decay will be satisfied by the aeration rate.

The expectation of the TMDL will be to eliminate the anaerobic conditions. Once the TMDL is successful dissolved oxygen will not fall below water quality standards. If the residence time of B 11 water in the Columbia Slough is longer than the time to critical deficit then the loading capacity is established by the critical oxygen deficit. If the residence time of water in the Slough is less than the time to critical oxygen deficit the loading capacity is defined by the dissolved oxygen deficit that occurs at the time water leaves the Columbia Slough and is diluted by water from the Columbia and Willamette Rivers.

The potential range for time to critical dissolved oxygen deficit was calculated for a range of Kd and  d as defined above, and for a range of the estimated Ka and  a with an assumed standard error of 0.03 ( USEPA). An initial oxygen deficit of zero was assumed. A total of 1000 calculations representing the potential ranges of Ka and Kd as adjusted by temperature were made for defined conditions of temperature and flow. The median calculated Tc for a flow of 100 cfs and stage of 15 MSL was > 22 days ( Figure 10).

Residence time is dependent upon the stage and discharge ( Table 5). The time to critical deficit is dependent substantially on the aeration and deoxygenation rates, which in turn are dependent upon temperature, stage, and discharge. However, under the assumed reasonable worst case conditions it appears the time to critical deficit is likely to be greater than the residence time of water in the Columbia Slough. The LC is determined by the residence time of water in the Slough.

OXYGEN DEMAND LOADS: The instream dissolved oxygen is in part dependent upon the loads of oxygen demanding material discharged to the Slough. The relative contribution of sources varies depending upon whether rainfall runoff or deicing is occurring. The substantive loads that are estimated with existing data include the de icing loads, storm water loads, and the net background loads. Critical Time @ 100 cfs, 15MSL 0 50 100 150 200 250 300 5 10 15 20 25 30 35 40 45 More Days Frequency .00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00%

Frequency Cumulative %

Figure 10, Time to critical DO deficit Q/ MSL 10 15 20 100 7.6 11.2 11.7 200 3.3 4.9 5.1 300 2.8 3.5 3.7 Table 5: Estimated Residence Time, Lower Slough only B 12 Combined Sewer Overflows: A substantial oxygen demand loads is contributed by CSOs. Current efforts will largely eliminate the CSOs. With elimination the WLA for CSOs will be zero and are therefore not further evaluated as part of the TMDL.

Sediment Oxygen Demand: Sediment oxygen demand ( SOD) can substantively influence dissolved oxygen. A single measure of SOD in the Columbia Slough of 2g 02/ m2/ day is similar to the sediments of other Western Oregon rivers. Sediment oxygen demand is influenced by ambient temperature with a default theta (  ) of 1.072 ( USEPA). The SOD was presumed not significant compared to other sinks of oxygen for this analysis.

De icing Loads: De icing loads to the Columbia Slough were estimated using COD measures and presumed flow by Fish ( 1996). Wells and Berger ( 1995) estimated contributions from de icing by using field data and estimates for rates of aeration and deoxygenation. No direct instream information is available to demonstrate the influence that the de icing loads have on instream BOD5 concentrations. Estimates of the influence of de icing loads were compared to instream concentrations using simple dilution calculations and the results may be compared to instream BOD5 measures. Unfortunately, available instream measures occurred during different periods than the measured de icing loads. The instream concentrations would also be influenced by several processes such as dispersion and decay. Comparisons may only provide an approximation of whether the observed instream concentrations are within a reasonable order of magnitude of what would be expected by de icing loads.

De icing loads of BOD were estimated by Fish ( 1996) for events in January and February of 1996. The BOD5 concentrations were estimated from COD data using empirical correlations developed for the airport. The loads were estimated using presumed " worst case" pumping discharge rates. Peak loads calculated for the February event were on the order of 3.1 lb./ second at 6,470 mg/ l BOD5. During the January event peak loads were on the order of 2 lb./ second at 1784 mg/ l BOD5. The resulting instream concentrations are not available. Estimates of loads using presumed flow ranges are similar to observed peak instream BOD5. B 13 The instream BOD5 concentrations resulting from the estimated de icing loads can be estimated by a simple mass balance using presumed stream flow ( Figure 11). This exercise demonstrates that loads would be periodic pulses moving through the Columbia Slough. Subsequent dispersion would reduce maximum concentrations and act to spread out the period of the pulse.

During the January event the loads were derived principally from subbasin six ( 6) of the Port. Since flow data was not readily available the instream concentrations was calculated for three ( 3) assumed discharge rates ( 150, 200, 300 cfs) and an ambient concentration of 1 mg/ l BOD5 ( Figure 11). On other occasions instream measures of > 80 mg/ l have been reported. The reported instream BOD5 levels of > 80 mg/ l do not appear unreasonable for peak ambient concentrations for an event of this magnitude.

Maximum instream concentrations were estimated for the February 1996 event for presumed ambient flows of between 200 and 1,000 cfs and background BOD5 of 1 mg/ l ( Figure 12). Instream flow and BOD5 measures are not available. Significant deicing load contributions occurred for both subbasin six ( 6) and seven ( 7). The peak loads for both were assumed to occur simultaneously.

The Willamette river was near or above flood stage during this period. However, the actual flow rate in the Slough is not known. Peak BOD5 loads in the range of observed peak concentrations of 80 mg/ l or greater would not be unreasonable.

Storm water BOD5 loads: Numerous efforts have been made to estimate the BOD contribution of storm water to the Slough system. Storm water BOD5 loading have been estimated for the City of Portland as part of earlier CSO studies. Wells and Berger ( 1995) estimated storm water loads through calibration of receiving water quality models. Municipal storm water permits predicted storm water loads using runoff equations and assigned concentrations using field data. Each of these efforts is discussed below.

Urban runoff modeling ( SIMPTM) conducted by OTAK estimated an overall storm water BOD5 of   5 mg/ l for the City of Portland. The SIMPTM model used local rainfall data, and Bellevue Instream BOD using assumed flow, January 18 19 event 0 20 40 60 80 100 120 140 0 5 10 15 20 Hours BOD5 150 200 300 Figure 11, Instream BOD Estimated BOD using Estimated Peak Mass Load, February Event and Assumed Discharge 0 50 100 150 200 250 0 200 400 600 800 1000 Discharge mg/ l BOD Figure 12, Estimated BOD B 14 NURP data supplemented with data collected in Portland. The SIMPTM program simulates pollutant loading from land use and incorporates the influence of local drainage conveyance systems on the total loading of particulate and associated parameters, such as BOD.

In the MS4 permit applications the overall average BOD5 load is dependent upon the mix of land use, runoff coefficients used for each land use and assigned BOD5 concentration. The simulations do not account for any losses of BOD5 through the storm water system. This information was used to develop storm water loading estimates for the Columbia Slough as part of the Columbia Slough Water Body Assessment ( CH2MHill 1995).

Wells and Berger ( 1995) cite calibration with field BOD5 and dissolved oxygen data as demonstrating that the estimates made by OTAK better fit observed conditions than the more simple models used to develop storm water permit estimates. As part of the calibration efforts to better represent observed instream DO and BOD5 Wells and Berger reduced storm water concentrations as estimated in the Water Body Assessment ( CH2Mhill, 1995) by 50% and 75 %. Although this calibration improved model comparison to field conditions Wells believed additional reduction may be warranted.

Table 6 summarizes these storm water BOD estimates.

Table 6: Summary of estimates of storm water BOD concentration DEQ initially used 11 mg/ L as the concentration of BOD5 from storm water in the estimation of the BOD loading capacity. The City of Portland commented that the representative storm water BOD5 concentrations should be reduced from 11 mg/ L to near 5 mg/ L. To respond to this comment, DEQ estimated the storm water BOD concentration by two methods: calculation of a flow weighted mean urban runoff concentration and solution of a simple mass balance. These two methods are discussed in detail below.

Flow weighted mean method: A flow weighted mean urban runoff BOD5 concentration for the Columbia Slough was derived using land use distributions and associated event mean concentrations. The results of this calculation are summarized in Table 7. Source mg/ L BES SIMPTM ( mean) 5.2 Gresham MS4 ( mean) 5 Portland MS4 ( mean) 19 WBA CH2MHill ( mean) 21 Wells and Berger calibration ( mean) 11 ( 50% reduction of initial calibration) B 15 Table 7: Flow weighted man The calculated weighted mean concentration of 20.39 mg/ l BOD5 is greater than the recommended 5 mg/ l to represent urban runoff. The BOD associated with land use classification for vacant and open spaces were below the proposed 5 mg/ l BOD5. The land use classifications for residential, industrial, commercial, and traffic corridor had event mean concentrations exceeding the proposed 5 mg/ l. Available data suggest that industrial storm water provides a significant contribution to the overall storm water BOD5 loads to the Columbia Slough. Industrial storm water has higher BOD5 concentrations than other land uses.

Mass balance: A simple comparison of dilution rates and instream concentrations can be used to estimate storm water concentrations. This approach is similar to the calibration efforts used by Wells and Berger for a single event. A calibrated SWMM model was used to estimate urban storm water flows and transport these flows through the Slough. Backwater and tidal effects were ignored. Dilution was estimated by assuming a constant background flow of 75 cfs in the Slough. The BOD concentration uninfluenced by storm water was assumed to consistent with the median BOD of 2.5 mg/ l BOD5. The dilution was calculated for each day and specific location where BOD was monitored in the Slough. The storm water concentration was then directly calculated as:

{ } C Q Q Q C C C d storm background simulate background observed background observed =     + . The simple mass balance provides an indication of how close calibrated storm water concentrations from multiple sampling efforts rather than a single effort would compare to the simulated storm water runoff concentrations. The results of this calculation are summarized in Table 8.

Table 8, storm water BOD5 concentrations This analysis suggest that the City of Portland's calibration estimate that storm water typically contributes 5 mg/ l BOD5 to the Slough is reasonable. The interquartile range for estimated BOD from storm water varies from 2 to > 15 mg/ l. Mean, median, and geometric mean estimates varied between 5.3 to 28 mg/ l, but were typically less than 11 mg/ l. The highest estimates may reflect the influence of de icing materials on instream BOD5 concentrations used to calculate storm water loads. The reason for the LAND USE EMC RUN OFF AREA Residential 9.35 0.39 0.105 Industrial 54.05 0.68 0.14 Commercial 10.78 0.82 0.164 Open 3.84 0.14 0.132 Vacant 3.84 0.41 0.438 Traffic 13.65 0.91 0.023 ( average) 15 Sum ( BOD* Runoff* area) =

Sum ( Runoff* area) 20.39 MCDD1 LOWER RM 6.9 LOWER RM 4.9 25% 2.0 2.0 2.0 Mean 28 8.6 11.4 Median 6.0 8.8 7.7 Geomean 7.0 5.3 8.3 75% 15.6 11.7 7.4 B 16 discrepancy between the estimates based on instream calibration and the storm water model estimated are not known. Substantial errors could occur because of uncertain estimates for dilution, hydrologic transport, loss mechanisms, and uncertain load/ land use/ runoff estimates.

It appears reasonable to conclude that the instream BOD5 concentrations are less than would be expected from simple dilution models using storm water concentrations estimated using simple runoff models ( i. e. the flow weighted mean method). The reduction is on the order of 50% of the load, and may be greater. However, further decrease beyond the proposed 50% reduction may imply precision that does not exist. The storm water BOD5 contribution is therefore estimated as 10 mg/ L.

Background BOD5  BODu: The background BOD5 as applied represents the concentration of BOD5 originating from natural anthropogenic sources other than storm water and de icing loads. The mean ( log normalized) of 2.5 mg/ l BOD5 may provide a site specific estimate of background BOD5 that is consistent with the relatively high range of BOD observed in the Slough compared to other western Oregon streams.

A background flow of 70 CFS is consistent with the volume of water reported in the Columbia Slough Water Body Assessment for groundwater and upstream sources of water.

No direct measure of the background ultimate oxygen demand have been made. The background BOD deoxygenation rate was presumed to be the same as the rate for glycols. This rate may be greater than occurs for background BOD and provides a conservative estimate of BODu.

( BOD BOD e u Kd =     5 5 1 * .) The estimated BODu is   4.9 mg/ l.

DERIVATION OF THE TMDL ( LC WLA LA MOS): A dissolved oxygen TMDL is derived for the Columbia Slough using a very simple analytical solution to a dissolved oxygen balance. A much more complex model is available. However, the lack of robust synoptic data sets providing coincident loading and ambient information results in substantial uncertainty for describing the observed oxygen depletion in the Slough. Additionally, the uncertainty on the decay rates of glycols and the influence of temperature on decay rates increases the opportunity for discussion and debate about model calibration and application for the development of TMDLs. The lack of coincident ambient data and uncertainty about decay rates results in a large number of degrees of freedom and a more complex evaluation may not be more precise than a simple approach.

The federal Clean Water Act clearly states two ( 2) conditions that influence the TMDL. The TMDLs need to be established with existing data. The TMDL needs to contain an appropriate margin of safety to account for existing lack of knowledge.

The phased TMDL approach allows the refinement of the initial TMDL if more or better information becomes available. The implementation plan can include efforts to obtain information B 17 needed to modify the TMDL. The phased TMDL approach allows the TMDL to be modified using information developed during previous phases.

Initial TMDL A simple oxygen balance was developed to identify the initial TMDL and to test the sensitivity of the various rates and coefficients on the potential TMDLs. Estimates of the stream loading capacity were determined using the best available information on deoxygenation and aeration rates, and the influence of temperature on these rates. A reasonable critical condition for dissolved oxygen concentration was used to define the loading capacity.

The simple oxygen balance provides a means to discuss and evaluate alternative allocation strategies and is presented in terms of the oxygen deficit at a time ( t):

{ } { } { } DO DO K K K e e BOD DO DOe s t d a d K t K t u s K t d d a   =     +

0 0 , where S = saturation.

The initial TMDL, including a margin of safety can be described using the simple oxygen balance. The simple oxygen balance was modified to include the influence of dispersion on pulse loads of BOD. As a result of this modification, the de icing events are restricted to a single day.

This information can be used to determine whether further model refinement is needed to reduce the existing uncertainty. Reducing uncertainty will in effect allow a shift of the margin of safety to specific waste loads. This information may be used to focus discussion on what data and information is needed to refine the understanding of the oxygen depletion in the Columbia Slough.

Because of the magnitude of the observed DO problems it is reasonably assumed that further model refinement will occur. To date the information needed has not been collected. A phased TMDL will assure that the information needed will be collected in a timely manner and that controls will be implemented with an appropriate margin of safety.

From the information reviewed above the reasonable design conditions for determining the loading capacity ( LC) are:

Kd( 20) = 0.143/ day ( at 20C) Kd( 8) = 0.045/ day ( at 8C) Theta Kd = 1.10 Theta Ka = 1.024 Ka = 0.107/ day ( at 8C) Temperature = 8 C Background BOD5 = 2.5 mg/ l, Background BODu = 4.9 mg/ l Storm water BOD5 = 10 mg/ L De icing Bod5 = range of 100 to 2000 mg/ L to meet dissolved oxygen criteria time of discharge = 1 day Exx ( dispersion) = 2 for Q < 100 CFS Exx ( dispersion) = 20 for Q> 200 CFS Q ( total flow) = 2.83 m/ s ( 100 CFS), 5.66 m/ s ( 200 CFS), 8.5 m/ s ( 300 CFS) B 18 The residence time of water for calculating minimum dissolved oxygen condition includes the travel time from the airport to MCDD1 in the Upper Slough, and for the travel time through the Lower Columbia Slough. At a stage of 15 MSL in the Lower Slough the residence time varies from a < 5 days to near 12 days depending on discharge ( Table 9).

Table 9, residence time ( days)

The design conditions represent the best estimate of model input values and a reasonable set of hydraulic and temperature conditions that have been observed to generate critical dissolved oxygen depletion in the Columbia Slough.

Hydraulic conditions are different between the Upper and Lower Slough. The preliminary analysis suggest that the Lower Slough is more likely than the Upper Slough to have reduced oxygen levels due to elevated BOD. Allocations are established to achieve the DO criteria in the Lower Slough.

The simple oxygen balance was solved to determine the loading capacity of instream BOD. The objective of the LC is to achieve dissolved oxygen criteria of 6.5 mg/ l as a long term average, 5.0 as an event minimum average, and 4.0 as an absolute minimum. The criteria are used to define the LC for an event hourly maximum, event mean, and long duration discharge. This approach allows the LC and subsequent WLAs to vary dynamically with pulse events of the storm water driven loads.

Allocation Strategy: Several allocation strategies are available. The three ( 3) principle allocations are for background, storm water, and de icing loads. The TMDL is described as the instream target BOD5 concentration and varies with flow ( TMDL ( kg/ d) = BOD5( mg/ l) * Q( m/ s) * conversion factor).

Several alternatives were evaluated for distributing loads between storm water and de icing loads. From this review there appears to be two ( 2) reasonable strategies.

1) Allocate the storm water loads at their current estimated concentration and loads. The reduction in loads needed to achieve the LC would be taken from the de icing load.

2) Equal relative efforts: Under the equal relative effort alternative the reduction of both storm water and de icing loads is proportional to the calculated increase in BOD5 in the Columbia Slough. There are two ( 2) alternative methods used to define what is equal equivalent effort. Information presented by Wells and Berger ( 1995) was used as the reference condition for deriving equal relative efforts. The WLA would be determined as the reduction from the existing reference condition. The initial allocation reduced 4.5 pounds of de icing load for each pound of storm water. Alternatively, if the mass ratio is perceived to be the equitable representation of equivalent effort there would be 3.8 pounds BOD reduced in de icing load for each pound of storm water ( Table 10). Q Lower Upper Residence 100 11.2 2 13.2 200 4.9 1 5.9 300 3.5 1 4.5 B 19 Table 10, equal mass reduction calculation The relative influence of storm water loads would be unique for each set of streamflow, runoff, and de icing event conditions. The relative load is also dependent upon the uncertain estimates of both storm water and deicing quality and loads. The relative reduction is unique for each condition. It would not be possible to derive unique reductions for each condition.

Reasonable Margin of Safety: A TMDL must be established with a reasonable margin of safety to account for uncertainty in existing information on loads and receiving water response. The margin of safety also needs to account for the uncertainty in achieving the assigned load allocations. A substantial amount of uncertainty exists in the current estimates of the loading capacity. A margin of safety of 20% was assigned to the estimates of LC for the three ( 3) flow regimes and three ( 3) oxygen criteria.

The amount of uncertainty associated with the selection of Kd,  kd, Ka, and  ka was determined by defining probability density functions. The mean and defined standard deviation for Kd, and  kd are described above. The calculated Ka, and  ka were assigned a coefficient of variation of 0.03 from USEPA guidelines for conducting uncertainty analysis ( QUAL2EU). All distributions were presumed to be normal. The loading capacity was determined as the Lo that would create a deficit equal to the difference between saturation and the state water quality standard ( dispersion was not included in this analysis): DO DO K K K e e s stnd d d a K t K t d a

        ( ) . The dissolved oxygen was assumed to be initially at saturation. The residence time of water in the Slough was derived above and estimated to be less than the critical time for achieving minimum dissolved oxygen. The distribution of calculated loading capacities is presented in Figure 13.

The calculation of LC depends on both the selection of a reference residence time and the physical hydraulic conditions used. The approach used presumed reasonable worst case physical hydraulic conditions of a 15 ft MSL stage, and a temperature of 8C. The loading capacity was determined for a criteria of 4.0 mg/ l DO. A greater loading capacity would be expected under less severe hydraulic conditions. A greater range for loading capacity would be estimated if the stage, temperature, and residence time were allowed to vary, however the LC is described for specific discharge levels. A discharge of 200 cfs was used in the uncertainty analysis. C Q Mass Storm 10 345.0 18596 de ice 2000 6.5 70070 BKG 2.5 70.0 943 8.7 BKG + Storm 39 BKG + Storm + de ice 39/ 8.7 = 4.5 Mass de ice / Mass Storm : 70070/ 18596 = 3.8 Histogram 0 50 100 150 200 250 300 350 10 15 20 25 30 35 40 45 50 55 60 65 70 More BOD( 5) BIN Range Frequency .00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00%

Frequency Cumulative %

Figure 13, distribution of estimated LC B 20 An appropriate margin of safety needs to provide reasonable assurance that achievement of the WLAs will result in achievement of water quality standards. The margin of safety should also provide an objective measure of the uncertainty with existing knowledge. The allocation to the margin of safety may be redistributed if additional information is developed which improves the precision of the estimated loading capacity.

Table 11, range of LC The margin of safety was defined as a function of the normal variate ( z) for the range of LC ( Figure 14). Over 68% of the values fall between +/ 1z, and over 95% of the values fall between +/ 2z. A range of 1z indicates the most likely range and 2z represents the reasonably potential range ( Table 11).

The MOS is calculated as: 215 168 215 . .

.   , = 21.8%,   20%. This value represents one standard deviation around the average LC calculated. A MOS of 20% is applied to all flow rates and DO criteria. Allocating a margin of safety reduces the amount of BOD that may be distributed to other sources. Additional data could act to reduce the MOS and allow some of the mass to be reallocated.

TMDL LC, WLAs, LA s: Allocations are expressed as a loading capacity that varies with flow as determined for a reasonable design condition.

The allocations are distributed to three ( 3) classes of sources; background, storm water and deicing The storm water loads are divided between permitted industrial storm water and urban runoff from areas managed by the designated management agencies. The storm water and deicing loads are for those loads that reach the Columbia Slough, rather than those loads that are generated. Both storm water and de icing loads may be treated between where they are generated and the Slough. A 20% margin of safety is taken from the LC and reserved.

The allocation for the airport is divided between the Port of Portland ( PDX) and the Oregon Air National Guard ( ANG).

Storm water runoff allocations have been split between industrial and urban runoff. The storm water target loads may also be expressed as an event mean target concentration. The storm water BOD5 reaching the Columbia Slough is allocated to 46% originating from permitted industrial storm water and 54% from other urban runoff. Distribution of estimated LC for BOD( 5)

1 10 100  5  4  3  2  1 0 1 2 3 4 5 Z mg/ l Figure 14: Estimated LC vs Normal Variate ( Z)

z LC ( mg/ l) BOD5 % difference Low High Low Avg. High Range ( avg. low)/ avg. 1.95 1.98 13.3 21.5 35.6 22.3 38.0% 1.00 1.00 16.8 21.5 27.9 11.1 21.8% B 21 Future Growth and Development From application of the SIMPTM model the City of Portland predicted a 150% increase in storm water pollutant loading over current loads to the Columbia Slough ( City of Portland 1989). Future growth therefore receives 1/ 3 of the storm water allocation.

The allocation of mass loads is summarized in Table 12.

Table 12, BOD allocations REFERENCES CH2MHill 1995, Waterbody Assessment Columbia Slough TMDL Development, written for the City of Portland.

City Of Portland, Bureau of Environmental Services, 1989, Columbia Slough Planning Study Background Report.

EPA, 1992, Technical Guidance Manual for Performing Waste Load Allocations, Book ii: Streams and Rivers.

Fish, William, Ph. D., 1996, Portland International Airport Deicing Impact Study 1995 1996, Final Report, Prepared for the Port of Portland.

Hendrickson, Nancy, 1997, Discussion of City of Portland BOD data.

Thomann, Robert, and Mueller, John, 1987, Principles of Surface Water Quality Modeling and Control, Harper and Row, Publishers, Inc.

Wells S. A., and C. J. Berger ( 1995) Hydraulic and Water Quality modeling of the Upper and Lower Columbia Slough: Model calibration, verification, and management alternatives report for 1992 1995. Research supported by the City of Portland BES. Flow ( m3/ sec) BKG Future Growth DMA Industrial SW PDX ANG MOS TMDL WLA to achieve 4.0 mg/ L DO criteria, BOD5, kg/ day 2.83 428 188 201 175 3342 413 1200 5947 5.66 428 869 931 809 8752 1082 3237 16108 8.50 428 1585 1702 1479 11641 1439 4568 22842 11.33 428 2435 2608 2267 17679 2185 6981 34583 WLA to achieve 5.0 mg/ L DO criteria, BOD5, kg/ day 2.83 428 187 200 174 2801 346 1034 5170 5.66 428 854 914 795 7225 893 2784 13893 8.50 428 1553 1664 1446 9645 1192 3992 19920 11.33 428 2361 2529 2198 14825 1832 6089 30262 WLA to achieve 6.5 mg/ L, DO criteria, BOD5, kg/ day 2.83 428 183 198 172 1978 244 801 4004 5.66 428 822 889 773 4935 610 2114 10571 8.50 428 1500 1607 1396 6652 822 3132 15537 11.33 428 2251 2411 2095 10504 1298 4795 23782 B 22 Wells S. A., C. J. Berger, and M. B. Eberle ( 1996). Modeling and Monitoring the Columbia Slough System 1995/ 1996. Research supported by the City of Portland., BES.


[Federal Register Volume 86, Number 43 (Monday, March 8, 2021)]
[Rules and Regulations]
[Pages 13196-13200]
[FR Doc No: 2021-04720]

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 180

[EPA-HQ-OPP-2019-0665; FRL-10020-34]

Quizalofop ethyl; Pesticide Tolerances

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This regulation establishes tolerances for residues of
quizalofop ethyl in or on multiple commodities which are identified and
discussed later in this document. The Interregional Project Number 4
(IR-4) requested these tolerances under the Federal Food, Drug, and
Cosmetic Act (FFDCA).

DATES: This regulation is effective March 8, 2021. Objections and
requests for hearings must be received on or before May 7, 2021, and
must be filed in accordance with the instructions provided in 40 CFR
part 178 (see also Unit I.C. of the SUPPLEMENTARY INFORMATION).

ADDRESSES: The docket for this action, identified by docket
identification (ID) number EPA-HQ-OPP-2019-0665, is available at http://www.regulations.gov or at the Office of Pesticide Programs Regulatory
Public Docket (OPP Docket) in the Environmental Protection Agency
Docket Center (EPA/DC), West William Jefferson Clinton Bldg., Rm. 3334,
1301 Constitution Ave. NW, Washington, DC 20460-0001. The Public
Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through
Friday, excluding legal holidays. The telephone number for the Public
Reading Room is<PHONE_NUMBER>, and the telephone number for the OPP
Docket is<PHONE_NUMBER>.
    Due to the public health concerns related to COVID-19, the EPA
Docket Center (EPA/DC) and Reading Room is closed to visitors with
limited exceptions. The staff continues to provide remote customer
service via email, phone, and webform. For the latest status
information on EPA/DC services and docket access, visit https://www.epa.gov/dockets.

FOR FURTHER INFORMATION CONTACT: Marietta Echeverria, Acting Director,
Registration Division (7505P), Office of Pesticide Programs,
Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Washington,
DC 20460-0001; main telephone number:<PHONE_NUMBER>; email address:
<EMAIL_ADDRESS>
SUPPLEMENTARY INFORMATION:

I. General Information

A. Does this action apply to me?

    You may be potentially affected by this action if you are an
agricultural producer, food manufacturer, or pesticide manufacturer.
The following list of North American Industrial Classification System
(NAICS) codes is not intended to be exhaustive, but rather provides a
guide to help readers determine whether this document applies to them.
Potentially affected entities may include:
     Crop production (NAICS code 111).
     Animal production (NAICS code 112).
     Food manufacturing (NAICS code 311).
     Pesticide manufacturing (NAICS code 32532).

B. How can I get electronic access to other related information?

    You may access a frequently updated electronic version of EPA's
tolerance regulations at 40 CFR part 180 through the Government
Publishing Office's e-CFR site at http://www.ecfr.gov/cgi-bin/text-idx?&c=ecfr&tpl=/ecfrbrowse/Title40/40tab_02.tpl.

C. How can I file an objection or hearing request?

    Under FFDCA section 408(g), 21 U.S.C. 346a, any person may file an
objection to any aspect of this regulation and may also request a
hearing on those objections. You must file your objection or request a
hearing on this regulation in accordance with the instructions provided
in 40 CFR part 178. To ensure proper receipt by EPA, you must identify
docket ID number EPA-HQ-OPP-2019-0665 in the subject line on the first
page of your submission. All objections and requests for a hearing must
be in writing and must be received by the Hearing Clerk on or before
May 7, 2021. Addresses for mail and hand delivery of objections and
hearing requests are provided in 40 CFR 178.25(b).
    In addition to filing an objection or hearing request with the
Hearing Clerk as described in 40 CFR part 178, please submit a copy of
the filing (excluding any Confidential Business Information (CBI)) for
inclusion in the public docket. Information not marked confidential
pursuant to 40 CFR part 2 may be disclosed publicly by EPA without
prior notice. Submit the non-CBI copy of your objection or hearing
request, identified by docket ID number EPA-HQ-OPP-2019-0665, by one of
the following methods:
     Federal eRulemaking Portal: http://www.regulations.gov.
Follow the online instructions for submitting comments. Do not submit
electronically any information you consider to be CBI or other
information whose disclosure is restricted by statute.
     Mail: OPP Docket, Environmental Protection Agency Docket
Center (EPA/DC), (28221T), 1200 Pennsylvania Ave. NW, Washington, DC
20460-0001.
     Hand Delivery: To make special arrangements for hand
delivery or delivery of boxed information, please follow the
instructions at https://www.epa.gov/dockets/where-send-comments-epa-dockets. Additional instructions on commenting or visiting the docket,
along with more information about dockets generally, is available at
http://www.epa.gov/dockets.

II. Summary of Petitioned-For Tolerance

    In the Federal Register of May 8, 2020 (85 FR 27346) (FRL-10008-
38), EPA issued a document pursuant to FFDCA section 408(d)(3), 21
U.S.C. 346a(d)(3), announcing the filing of a pesticide petition (PP
9E8803) by IR-4, Rutgers, the State University of New Jersey, 500
College Road East, Suite 201W, Princeton, NJ 08540. The petition
requested that 40 CFR 180.441 be amended by establishing tolerances for
residues of the herbicide quizalofop ethyl convertible to 2-methoxy-6-
chloroquinoxaline, expressed as quizalofop ethyl, in or on carinata at
1.5 parts per million (ppm); cottonseed subgroup 20C at 0.1 ppm; fruit,
pome, group 11-10 at 0.1 ppm; fruit, small, vine climbing, except fuzzy
kiwifruit, subgroup 13 07F at 0.1 ppm; fruit, stone, group 12-12 at 0.1
ppm; pennycress, meal at 2 ppm; pennycress, seed at 1.5 ppm; and
sunflower subgroup 20B at 3 ppm. Additionally, the petition requested,
upon approval of the above tolerances, to remove the existing
tolerances in 40 CFR 180.441(a) in or on cotton, undelinted seed at 0.1
ppm and sunflower, seed at 1.9 ppm. That document referenced a summary
of the petition prepared by AMVAC Chemical Corporation, the registrant,
which is available in the docket, http://www.regulations.gov. Two
comments were received on the notice of filing. EPA's response to these
comments is discussed in Unit IV.C.
    Based upon review of the data supporting the petition, EPA
corrected several tolerance definitions and is not establishing a
tolerance on pennycress, meal, as proposed by the petitioner. The
reasons for these changes are explained in Unit IV.D.

III. Aggregate Risk Assessment and Determination of Safety

    Section 408(b)(2)(A)(i) of FFDCA allows EPA to establish a
tolerance (the legal limit for a pesticide chemical residue in or on a
food) only if EPA determines that the tolerance is ``safe.'' Section
408(b)(2)(A)(ii) of FFDCA defines ``safe'' to mean that ``there is a
reasonable certainty that no harm will result from aggregate exposure
to the pesticide chemical residue, including all anticipated dietary
exposures and all other exposures for which there is reliable
information.'' This includes exposure through drinking water and in
residential settings but does not include occupational exposure.
Section 408(b)(2)(C) of FFDCA requires EPA to give special
consideration to exposure of infants and children to the pesticide
chemical residue in establishing a tolerance and to ``ensure that there
is a reasonable certainty that no harm will result to infants and
children from aggregate exposure to the pesticide chemical residue. . .
.''
    Consistent with FFDCA section 408(b)(2)(D), and the factors
specified in FFDCA section 408(b)(2)(D), EPA has reviewed the available
scientific data and other relevant information in support of this
action. EPA has sufficient data to assess the hazards of and to make a
determination on aggregate exposure for quizalofop ethyl including
exposure resulting from the tolerances established by this action.
EPA's assessment of exposures and risks associated with quizalofop
ethyl follows.
    In an effort to streamline its publications in the Federal
Register, EPA is not reprinting sections that repeat what has been
previously published for tolerance rulemakings of the same pesticide
chemical. Where scientific information concerning a particular chemical
remains unchanged, the content of those sections would not vary between
tolerance rulemakings and republishing the same sections is
unnecessary. EPA considers referral back to those sections as
sufficient to provide an explanation of the information EPA considered
in making its safety determination for the new rulemaking.
    EPA has previously published a number of tolerance rulemakings for
quizalofop ethyl, in which EPA concluded, based on the available
information, that there is a reasonable certainty that no harm would
result from aggregate exposure to quizalofop ethyl and established
tolerances for residues of that chemical. EPA is incorporating
previously published sections from those rulemakings as described
further in this rulemaking, as they remain unchanged.
    Toxicological Profile. For a discussion of the Toxicological
Profile of quizalofop ethyl, see Unit III.A. of the February 23, 2018
rulemaking (83 FR 8006) (FRL-9972-30).
    Toxicological Points of Departure/Levels of Concern. For a summary
of the Toxicological Points of Departure/Levels of Concern used for the
safety assessment, see Unit III.B. of the December 1, 2016 rulemaking
(81 FR 86581) (FRL-9950-89).
    Exposure Assessment. Much of the exposure assessment remains the
same, although updates have occurred to accommodate exposures from the
petitioned-for tolerances. These updates are discussed in this section;
for a description of the rest of the EPA approach to and assumptions
for the exposure assessment, see Unit III.C. of the February 23, 2018
rulemaking.
    EPA's dietary exposure assessments have been updated to include the
additional exposure from the new uses of quizalofop ethyl on brassica
carinata; fruit, pome, group 11-10; fruit, small, vine climbing, except
fuzzy kiwifruit, subgroup 13-07F; fruit, stone, group 12-12; and
pennycress and the crop subgroup expansions for cottonseed subgroup 20C
and sunflower subgroup 20B. The assessment used the same assumptions as
the February 23, 2018 final rule concerning tolerance level residues
and default processing factors for all processed commodities except
sunflower oil, where an empirical factor was used.
    Updated average percent crop treated values were used for the
following crops that are currently registered for quizalofop-ethyl:
Beans, green: 2.5%; canola: 5%; cotton: 1%; dry beans/peas: 15%; peas,
green: 2.5%; soybeans: 2.5%; sugar beets: 1%; and sunflowers: 5%; and
100% crop treated for other registered and new uses of quizalofop
ethyl.
    Anticipated residue and PCT information. Section 408(b)(2)(F) of
FFDCA states that the Agency may use data on the actual percent of food
treated for assessing chronic dietary risk only if:
     Condition a: The data used are reliable and provide a
valid basis to show what percentage of the food derived from such crop
is likely to contain the pesticide residue.
     Condition b: The exposure estimate does not underestimate
exposure for any significant subpopulation group.
     Condition c: Data are available on pesticide use and food
consumption in a particular area, and the exposure estimate does not
understate exposure for the population in such area.
    In addition, the Agency must provide for periodic evaluation of any
estimates used. To provide for the periodic evaluation of the estimate
of PCT as required by FFDCA section 408(b)(2)(F), EPA may require
registrants to submit data on PCT.
    In most cases, EPA uses available data from United States
Department of Agriculture/National Agricultural Statistics Service
(USDA/NASS), proprietary market surveys, and the National Pesticide Use
Database for the chemical/crop combination for the most recent 6 to 7
years. EPA uses an average PCT for chronic dietary risk analysis. The
average PCT figure for each existing use is derived by combining
available public and private market survey data for that use, averaging
across all observations, and rounding to the nearest 5%, except for
those situations in which the average PCT is less than one. In those
cases, 1% is used as the average PCT and 2.5% is used as the maximum
PCT. EPA uses a maximum PCT for acute dietary risk analysis. The
maximum PCT figure is the highest observed maximum value reported
within the recent 6 years of available public and private market survey
data for the existing use and rounded up to the nearest multiple of 5%.
    The Agency believes that Conditions a, b, and c discussed above
have been met. With respect to Condition a, PCT estimates are derived
from Federal and private market survey data, which are reliable and
have a valid basis. The Agency is reasonably certain that the
percentage of the food treated is not likely to be an underestimation.
As to Conditions b and c, regional consumption information and
consumption information for significant subpopulations is taken into
account through EPA's computer-based model for evaluating the exposure
of significant subpopulations including several regional groups. Use of
this consumption information in EPA's risk assessment process ensures
that EPA's exposure estimate does not understate exposure for any
significant subpopulation group and allows the Agency to be reasonably
certain that no regional population is exposed to residue levels higher
than those estimated by the Agency. Other than the data available
through national food consumption surveys, EPA does not have available
reliable information on the regional consumption of food to which
quizalofop-ethyl may be applied in a particular area.
    Drinking water, non-occupational, and cumulative exposures.
Drinking

water exposures and residential (non-occupational) exposures are not
impacted by the new uses, and thus have not changed since the last
assessment. EPA's conclusions concerning cumulative risk remain
unchanged from the February 23, 2018 rulemaking.
    Safety Factor for Infants and Children. EPA continues to conclude
that there is reliable data to support the reduction of the Food
Quality Protection Act (FQPA) safety factor. See Unit III.D. of the
February 23, 2018 rulemaking for a discussion of the Agency's rationale
for that determination.
    Aggregate Risks and Determination of Safety. EPA determines whether
acute and chronic dietary pesticide exposures are safe by comparing
dietary exposure estimates to the acute population adjusted dose (aPAD)
and the chronic population adjusted dose (cPAD). Short-, intermediate-,
and chronic-term risks are evaluated by comparing the estimated
aggregate food, water, and residential exposure to the appropriate
points of departure to ensure that an adequate margin of exposure (MOE)
exists. For linear cancer risks, EPA calculates the lifetime
probability of acquiring cancer given the estimated aggregate exposure.
    An acute dietary exposure assessment was not conducted as
toxicological effects attributable to a single dose were not
identified. Chronic dietary risks are below the Agency's level of
concern of 100% of the cPAD: They are 92% of the cPAD for all infants
less than 1-year old, the population subgroup with the highest exposure
estimate. Quizalofop-ethyl is classified as a Category D chemical, i.e.
``Not Classifiable as to Human Carcinogenicity;'' therefore,
quantification of chronic risks using a non-linear approach will
adequately account for all chronic toxicity, including any potential
carcinogenicity that would result from exposure. There are no
registered or new uses of quizalofop ethyl that would result in
residential exposure, therefore the aggregate risk estimates are
equivalent to the chronic dietary (food and water) risk estimates and
are not of concern.
    Therefore, based on the risk assessments and information described
above, EPA concludes there is a reasonable certainty that no harm will
result to the general population, or to infants and children, from
aggregate exposure to quizalofop ethyl residues. More detailed
information about the Agency's analysis can be found at http://www.regulations.gov in the documents titled ``Quizalofop-P-ethyl.
Human-Health Risk Assessment in Support of the Proposed New Uses on
Carinata, Pennycress, Pome Fruit (Group 11-10), Stone Fruit (Group 12-
12), and Small Vine-climbing Fruit, Except Fuzzy Kiwifruit (Subgroup
13-07F); and Use Expansions for Sunflower and Cottonseed (Subgroups 20B
and 20C)'' in docket ID number EPA-HQ-OPP-2019-0665.

IV. Other Considerations

A. Analytical Enforcement Methodology

    For a discussion of the available analytical enforcement method,
see Unit IV.A. of the February 23, 2018 rulemaking.

B. International Residue Limits

    In making its tolerance decisions, EPA seeks to harmonize U.S.
tolerances with international standards whenever possible, consistent
with U.S. food safety standards and agricultural practices. EPA
considers the international maximum residue limits (MRLs) established
by the Codex Alimentarius Commission (Codex), as required by FFDCA
section 408(b)(4).
    The Codex has not established MRLs for quizalofop ethyl.

C. Response to Comments

    Although two comments were submitted to the docket in response to
the May 8, 2020 Notice of Filing, only one specifically related to this
tolerance action. The commenter requested that EPA deny IR-4's request
for tolerances for quizalofop ethyl on cotton sunflower seeds out of a
concern for the general health impacts of pesticides.
    Although the Agency recognizes that some individuals believe that
pesticides should be banned on agricultural crops, the existing legal
framework provided by section 408 of the FFDCA authorizes EPA to
establish tolerances when it determines that the tolerance is safe.
Upon consideration of the validity, completeness, and reliability of
the available data as well as other factors the FFDCA requires EPA to
consider, EPA has determined that the quizalofop ethyl tolerances are
safe. The commenter has provided no information indicating that a
safety determination cannot be supported.

D. Revisions to Petitioned-For Tolerances

    The commodity definition for carinata has been revised to brassica
carinata, seed; and brassica carinata, meal. The tolerance for brassica
carinata, seed will be established at 1.5 ppm; and the tolerance for
brassica carinata, meal will be established at 2 ppm. EPA is not
establishing a tolerance for pennycress, meal as requested by the
petitioner because the glucosinolates in pennycress meal restrict its
use to a livestock feedstuff, not a human food. EPA's current practice
is to set tolerances for livestock feedstuffs only if they are
significant, which is not the case for pennycress meal.

V. Conclusion

    Therefore, tolerances are established for residues of quizalofop
ethyl convertible to 2-methoxy-6-chloroquinoxaline, expressed as
quizalofop ethyl, in or on brassica carinata, meal at 2 ppm; brassica
carinata, seed at 1.5 ppm; cottonseed subgroup 20C at 0.1 ppm; fruit,
pome, group 11-10 at 0.1 ppm; fruit, small, vine climbing, except fuzzy
kiwifruit, subgroup 13-07F at 0.1 ppm; fruit, stone, group 12-12 at 0.1
ppm; pennycress, seed at 1.5 ppm; and sunflower subgroup 20B at 3 ppm.
Upon establishment of the above tolerances, the established tolerances
for cotton, undelinted seed at 0.1 ppm; and sunflower, seed at 1.9 ppm
will be removed as they are superseded by the new tolerances on
subgroups 20C and 20B, respectively.

VI. Statutory and Executive Order Reviews

    This action establishes tolerances under FFDCA section 408(d) in
response to petitions submitted to the Agency. The Office of Management
and Budget (OMB) has exempted these types of actions from review under
Executive Order 12866, entitled ``Regulatory Planning and Review'' (58
FR 51735, October 4, 1993). Because this action has been exempted from
review under Executive Order 12866, this action is not subject to
Executive Order 13211, entitled ``Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR
28355, May 22, 2001) or Executive Order 13045, entitled ``Protection of
Children from Environmental Health Risks and Safety Risks'' (62 FR
19885, April 23, 1997), nor is it considered a regulatory action under
Executive Order 13771, entitled ``Reducing Regulations and Controlling
Regulatory Costs'' (82 FR 9339, February 3, 2017). This action does not
contain any information collections subject to OMB approval under the
Paperwork Reduction Act (PRA) (44 U.S.C. 3501 et seq.), nor does it
require any special considerations under Executive Order 12898,
entitled ``Federal Actions to Address Environmental Justice in Minority
Populations and Low-Income Populations'' (59 FR 7629, February 16,
1994).
    Since tolerances and exemptions that are established on the basis
of a petition

under FFDCA section 408(d), such as the tolerances in this final rule,
do not require the issuance of a proposed rule, the requirements of the
Regulatory Flexibility Act (RFA) (5 U.S.C. 601 et seq.), do not apply.
    This action directly regulates growers, food processors, food
handlers, and food retailers, not States or Tribes, nor does this
action alter the relationships or distribution of power and
responsibilities established by Congress in the preemption provisions
of FFDCA section 408(n)(4). As such, the Agency has determined that
this action will not have a substantial direct effect on States or
Tribal Governments, on the relationship between the National Government
and the States or Tribal Governments, or on the distribution of power
and responsibilities among the various levels of government or between
the Federal Government and Indian Tribes. Thus, the Agency has
determined that Executive Order 13132, entitled ``Federalism'' (64 FR
43255, August 10, 1999) and Executive Order 13175, entitled
``Consultation and Coordination with Indian Tribal Governments'' (65 FR
67249, November 9, 2000) do not apply to this action. In addition, this
action does not impose any enforceable duty or contain any unfunded
mandate as described under Title II of the Unfunded Mandates Reform Act
(UMRA) (2 U.S.C. 1501 et seq.).
    This action does not involve any technical standards that would
require Agency consideration of voluntary consensus standards pursuant
to section 12(d) of the National Technology Transfer and Advancement
Act (NTTAA) (15 U.S.C. 272 note).

VII. Congressional Review Act

    Pursuant to the Congressional Review Act (5 U.S.C. 801 et seq.),
EPA will submit a report containing this rule and other required
information to the U.S. Senate, the U.S. House of Representatives, and
the Comptroller General of the United States prior to publication of
the rule in the Federal Register. This action is not a ``major rule''
as defined by 5 U.S.C. 804(2).

List of Subjects in 40 CFR Part 180

    Environmental protection, Administrative practice and procedure,
Agricultural commodities, Pesticides and pests, Reporting and
recordkeeping requirements.

    Dated: March 2, 2021.
Marietta Echeverria,
Acting Director, Registration Division, Office of Pesticide Programs.

    Therefore, for the reasons stated in the preamble, EPA is amending
40 CFR chapter I as follows:

PART 180--TOLERANCES AND EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES
IN FOOD

0
1. The authority citation for part 180 continues to read as follows:

    Authority: 21 U.S.C. 321(q), 346a and 371.

0
2. In Sec.  180.441, amend the table in paragraph (a)(1) as follows:
0
i. Add a table heading.
0
ii. Add alphabetically the entries ``Brassica carinata, meal''; and
``Brassica carinata, seed''.
0
iii. Remove the entry for ``Cotton, undelinted seed''.
0
iv. Add alphabetically the entries ``Cottonseed subgroup 20C'';
``Fruit, pome, group 11-10''; ``Fruit, small, vine climbing, except
fuzzy kiwifruit, subgroup 13-07F''; ``Fruit, stone, group 12-12''; and
``Pennycress, seed''.
0
v. Remove the entry for ``Sunflower, seed''.
0
vi. Add alphabetically the entry ``Sunflower subgroup 20B''.
    The additions read as follows:

Sec.  180.441  Quizalofop ethyl; tolerances for residues.

    (a) * * *
    (1) * * *

                       Table 1 to Paragraph (a)(1)
------------------------------------------------------------------------
                                                             Parts per
                        Commodity                             million
------------------------------------------------------------------------

                              * * * * * * *
Brassica carinata, meal.................................               2
Brassica carinata, seed.................................             1.5

                              * * * * * * *
Cottonseed subgroup 20C.................................             0.1

                              * * * * * * *
Fruit, pome, group 11-10................................             0.1
Fruit, small, vine climbing, except fuzzy kiwifruit,                 0.1
 subgroup 13-07F........................................
Fruit, stone, group 12-12...............................             0.1

                              * * * * * * *
Pennycress, seed........................................             1.5

                              * * * * * * *
Sunflower subgroup 20B..................................               3

                              * * * * * * *
------------------------------------------------------------------------

* * * * *
[FR Doc. 2021-04720 Filed 3-5-21; 8:45 am]
BILLING CODE 6560-50-P