### 58982 Federal Register / Vol. 78, No. 186 / Wednesday, September 25, 2013 / Proposed Rules

Messier-Dowty Service Bulletin A33/34–32– 283 or A33/34–32–284, both including Appendix A, both dated May 11, 2010, as applicable.

(l) New Optional Methods of Compliance

(1) Inspections for corrosion and damage to the protective treatment of the bogie beam, and repairs, done in accordance with Messier-Dowty Service Bulletin A33/34–32– 278, including appendices A and B, dated February 17, 2010, are acceptable methods of compliance with the requirements of paragraph (i)(1) of this AD.

(2) Modification of a MLG bogie beam, done in accordance with Messier-Dowty
Service Bulletins A33/34–32–283 and A33/ 34–32–284, both including Appendix A, both dated May 11, 2010, as applicable, is an acceptable method of compliance with the requirements of paragraph (i)(2) of this AD.

(m) New Parts Installation Limitation

As of the effective date of this AD, no person may install a MLG bogie beam on any airplane unless it is in compliance with the requirements and compliance times of paragraphs (g), (h), and (i) of this AD.

(n) New Reporting Requirement

Submit a report of the findings (both positive and negative) of the inspection required by paragraph (g) or (i) of this AD to Airbus, Customer Service Directorate, 1 Rond Point Maurice Bellonte, 31707 Blagnac Cedex, France, using the applicable reporting
sheet in Airbus Service Bulletin A330–32– 3237 or A340–32–4279, both dated January 18, 2011, at the applicable time specified in paragraph (n)(1) or (n)(2) of this AD.

(1) If the inspection was done on or after
the effective date of this AD: Submit the report within 90 days after the inspection.

(2) If the inspection was done before the effective date of this AD: Submit the report within 90 days after the effective date of this

AD.

(o) Other FAA AD Provisions

The following provisions also apply to this

AD:

(1) Alternative Methods of Compliance (AMOCs): The Manager, International Branch, ANM–116, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the International Branch, send it to ATTN: Vladimir Ulyanov, Aerospace Engineer, International Branch, ANM–116, Transport Airplane Directorate, FAA, 1601 Lind Avenue SW., Renton, WA 98057–3356; telephone 425–227–1138; fax 425–227–1149. Information may be emailed to: 9-ANM-116- AMOC-REQUESTS@faa.gov. Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. The AMOC approval letter must specifically reference this AD.

(2) Airworthy Product: For any requirement
in this AD to obtain corrective actions from a manufacturer or other source, use these actions if they are FAA-approved. Corrective actions are considered FAA-approved if they were approved by the State of Design Authority (or its delegated agent). For a repair method to be approved, the repair approval must specifically refer to this AD. You are required to ensure the product is airworthy before it is returned to service.

(3) Reporting Requirements: A federal agency may not conduct or sponsor, and a person is not required to respond to, nor shall a person be subject to a penalty for failure to comply with a collection of information subject to the requirements of the Paperwork Reduction Act unless that collection of information displays a current
valid OMB Control Number. The OMB
Control Number for this information collection is 2120–0056. Public reporting for
this collection of information is estimated to be approximately 5 minutes per response, including the time for reviewing instructions, completing and reviewing the collection of information. All responses to this collection of information are mandatory. Comments concerning the accuracy of this burden and suggestions for reducing the burden should be directed to the FAA at: 800 Independence Ave. SW., Washington, DC 20591, Attn: Information Collection Clearance Officer,

AES–200.

(p) Related Information

Refer to MCAI European Aviation Safety Agency (EASA) Airworthiness Directive 2012–0015, dated January 23, 2012, for related information, which can be found in
the AD docket on the internet at http:// www.regulations.gov.

Issued in Renton, Washington, on September 17, 2013.
Ross Landes, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 2013–23324 Filed 9–24–13; 8:45 am]

**BILLING CODE 4910–13–P**

**DEPARTMENT OF TRANSPORTATION**

**Federal Aviation Administration**

**14 CFR Part 39**

**[Docket No. FAA–2013–0796; Directorate Identifier 2013–NM–111–AD]** 

**RIN 2120–AA64**

**Airworthiness Directives; The Boeing Company Airplanes** 

**AGENCY :**  Federal Aviation Administration (FAA), DOT.

**ACTION :**  Notice of proposed rulemaking (NPRM).

**SUMMARY :**  We propose to supersede airworthiness directive (AD) 2013–07– 07, which applies to all The Boeing Company Model 737–600, –700, –700C, –800, –900, and –900ER series airplanes. AD 2013–07–07 requires inspecting to determine the part number of the attach pins of the horizontal stabilizer rear spar, and replacing certain attach pins. Since we issued AD 2013–07–07, we received inquiries from affected operators regarding the parts installation limitation and prohibition, and re-installation of certain attach pins that were removed for inspection. This proposed AD would clarify the parts installation limitation and prohibition, and would add a new requirement for certain airplanes on which certain attach pins were installed. We are proposing this AD to prevent premature failure of the attach pins, which could cause reduced structural integrity of the horizontal stabilizer to fuselage attachment, resulting in loss of control of the airplane.

**DATES :**  We must receive comments on this proposed AD by November 12,

2013.

**ADDRESSES :**  You may send comments, using the procedures found in 14 CFR 11.43 and 11.45, by any of the following
methods:

• Federal eRulemaking Portal: Go to http://www.regulations.gov. Follow the instructions for submitting comments.

• Fax: 202–493–2251.

• Mail: U.S. Department of Transportation, Docket Operations, M–30, West Building Ground Floor, Room W12–140, 1200 New Jersey Avenue SE., Washington, DC 20590.

• Hand Delivery: Deliver to Mail
address above between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H–65, Seattle, WA 98124–2207; telephone 206–544–5000, extension 1; fax 206– 766–5680; Internet https:// www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, WA. For information on the availability of this material at the FAA, call 425–227–1221.

Examining the AD Docket

You may examine the AD docket on
the Internet at http:// www.regulations.gov; or in person at the Docket Management Facility between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The AD docket contains this proposed AD, the regulatory evaluation, any comments received, and other information. The
street address for the Docket Office (phone: 800–647–5527) is in the

**ADDRESSES** section. Comments will be


### 58983 Federal Register / Vol. 78, No. 186 / Wednesday, September 25, 2013 / Proposed Rules

available in the AD docket shortly after receipt.

**FOR FURTHER INFORMATION CONTACT :**  Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM–120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057–3356; phone: 425–917–6440; fax: 425–917–6590; email: Nancy.Marsh@ faa.gov.

**SUPPLEMENTARY INFORMATION :** 

Comments Invited

We invite you to send any written relevant data, views, or arguments about this proposed AD. Send your comments
to an address listed under the

**ADDRESSES** section. Include ‘‘Docket No. FAA–2013–0796; Directorate Identifier 2013–NM–111–AD’’ at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of this proposed AD. We will consider all comments received by the closing date and may amend this proposed AD because of those

comments.

We will post all comments we receive, without change, to http:// www.regulations.gov, including any personal information you provide. We will also post a report summarizing each
substantive verbal contact we receive about this proposed AD.

Discussion

On March 28, 2013, we issued AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013) (‘‘AD 2013– 07–07’’), for all Model 737–600, –700, –700C, –800, –900, and –900ER series airplanes. AD 2013–07–07 requires inspecting to determine the part number of the attach pins of the horizontal stabilizer rear spar, and replacing certain attach pins. For airplanes having line numbers 1 through 3534, AD 2013– 07–07 also prohibited installing attach pins having part number (P/N)
180A1612–3 or 180A1612–4 that have 56,000 or greater flight cycles, unless
certain actions had been done. AD 2013–07–07 resulted from reports of an incorrect procedure used to apply the wear and corrosion protection surface coating to attach pins of the horizontal stabilizer rear spar. We issued AD 2013– 07–07 to prevent premature failure of the attach pins, which could cause reduced structural integrity of the horizontal stabilizer to fuselage attachment, resulting in loss of control of the airplane.

Actions Since AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013) Was Issued

Since we issued AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013), we have received inquiries from affected operators regarding the parts installation limitation and prohibition (i.e., paragraph (i)(1)) of AD 2013–07–07, and re-installation of certain attach pins of the horizontal stabilizer rear spar removed for inspection during

maintenance.

We have re-reviewed our response to commenter Japan Airlines (JAL) in AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013), and have determined it is necessary to provide further clarification. JAL requestedapproval of re-installation of any nondiscrepant attach pins having P/N
180A1612–3 or 180A1612–4 removed for inspection during maintenance.

We clarify that the term ‘‘install,’’ as used in AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013), can be interpreted as meaning ‘‘replace’’ while remaining within the intent of AD2013–07–07. That is, by simply reinstalling non-discrepant attach pins having P/N 180A1612–3 or 180A1612– 4 on the same airplane from which they were removed, the operator is not ‘‘installing’’ a new or different attach pin. Therefore, no alternative method of compliance is necessary to re-install non-discrepant attach pins having P/N
180A1612–3 or 180A1612–4 on the same airplane from which they were removed during maintenance not
associated with AD 2013–07–07.

To clarify paragraph (i)(1) of AD AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013), for airplanes having line numbers 1 through 3534, we have removed that paragraph and have added new paragraph (k) to this proposed AD. New paragraph (k) of this proposed AD would provide for installation of a attach pin of the horizontal stabilizer rear spar having P/N 180A1612–3 or 180A1612–4, provided it is replaced with an attach pin having P/N 180A1612–7 or 180A1612–8 prior to the accumulation of 56,000 total flight cycles on the pin.

In addition, for those same airplanes, paragraph (i)(1) of AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013), inadvertently allowed installation of an attach pin having P/N 180A1612–3 or 180A1612–4, even though the attach pin had been replaced with an attach pin having P/N 180A1612–7 or 180A1612–8, as required by paragraph (h) of AD 2013– 07–07. In light of this, we have added new paragraph (l) to this proposed AD for those airplanes on which attach pins having P/N 180A1612–3 or 180A1612– 4 were installed. New paragraph (l) of this proposed AD would require replacement of those attach pins with attach pins having P/N 180A1612–7 or 180A1612–8 prior to the accumulation of 56,000 total flight cycles on the attach pin, or within 1,000 flight cycles on the airplane after the effective date of this AD, whichever occurs later.

FAA’s Determination

We are proposing this AD because we
evaluated all the relevant information
and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.

Proposed AD Requirements

This proposed AD would retain certain requirements of AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013). This proposed AD would clarify the parts installation limitation and prohibition, and would add a new requirement for certain airplanes on which certain attach pins
were installed.

Costs of Compliance

We estimate that this proposed AD affects 1,050 airplanes of U.S. registry. The new proposed requirements add no significant economic burden over that specified in AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013). Those costs are repeated for the convenience of affected operators, as follows:



### E STIMATED 

### C OSTS

Action Labor cost Parts cost Cost per product Cost on U.S. operators

Inspection and attach pin replacement [retained actions from AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013)]. 39 work-hours × $85 per hour = $3,315. Up to $6,312 ............. Up to $9,627 ............. Up to $10,108,350.


### 58984 Federal Register / Vol. 78, No. 186 / Wednesday, September 25, 2013 / Proposed Rules

According to the manufacturer, some of the costs of this proposed AD may be covered under warranty, thereby reducing the cost impact on affected individuals. We do not control warranty coverage for affected individuals. As a result, we have included all costs in our

cost estimate.

Authority for This Rulemaking

Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Administrator. Subtitle VII, Aviation Programs, describes in more detail the scope of the Agency’s authority.

We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701, ‘‘General requirements.’’ Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority
because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking

action.

Regulatory Findings

We have determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would not
have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government.

For the reasons discussed above, I certify that the proposed regulation:

(1) Is not a ‘‘significant regulatory action’’ under Executive Order 12866,

(2) Is not a ‘‘significant rule’’ under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),

(3) Will not affect intrastate aviation in Alaska, and

(4) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

The Proposed Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part
39 as follows:

**PART 39—AIRWORTHINESS**
**DIRECTIVES**

■ 1. The authority citation for part 39
continues to read as follows:

Authority: 49 U.S.C. 106(g), 40113, 44701.

**§ 39.13 [Amended]**

■ 2. The FAA amends § 39.13 by removing airworthiness directive (AD) 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013), and adding the following new AD:

The Boeing Company: Docket No. FAA– 2013–0796; Directorate Identifier 2013–

NM–111–AD.

(a) Comments Due Date

The FAA must receive comments on this AD action by November 12, 2013.

(b) Affected ADs

(1) This AD supersedes AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013).

(2) This AD affects certain requirements of AD 2004–05–19, Amendment 39–13514 (69 FR 10921, March 9, 2004; corrected April 13, 2004 (69 FR 19313).

(c) Applicability

(1) This AD applies to all The Boeing Company Model 737–600, –700, –700C, –800, –900, and –900ER series airplanes, certificated in any category.

(2) Installation of Supplemental Type Certificate (STC) ST00830SE (http:// rgl.faa.gov/Regulatory

_and

_Guidance

_ Library/rgstc.nsf/0/408E012E008616A786257 8880060456C?Open Document&Highlight=st00830se) does not affect the ability to accomplish the actions required by this AD. Therefore, for airplanes on which STC ST00830SE is installed, a ‘‘change in product’’ alternative method of compliance (AMOC) approval request is not necessary to comply with the requirements of 14 CFR 39.17. For all other AMOC requests, the operator must request approval for an AMOC in accordance with the procedures specified in paragraph (m) of this AD.

(d) Subject

Joint Aircraft System Component (JASC)/ Air Transport Association (ATA) of America Code 55, Stabilizers.

(e) Unsafe Condition

This AD was prompted by reports of an incorrect procedure used to apply the wear and corrosion protection surface coating to attach pins of the horizontal stabilizer rear spar. We are issuing this AD to prevent premature failure of the attach pins, which could cause reduced structural integrity of the horizontal stabilizer to fuselage attachment, resulting in loss of control of the airplane.

(f) Compliance

Comply with this AD within the compliance times specified, unless already
done. (g) Retained Part Number Inspection
This paragraph restates the requirements of paragraph (g) of AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013). For airplanes having line numbers 1 through 3534 inclusive: Before the accumulation of 56,000 total flight cycles, or within 3,000 flight cycles after May 20, 2013 (the effective date of AD 2013–07–07), whichever occurs later, inspect to determine the part number of the attach pins of the horizontal stabilizer rear spar. A review of airplane maintenance records is acceptable in lieu of this inspection if the part number of the attach pin can be conclusively
determined from that review.

(h) Retained Replacement

This paragraph restates the requirements of paragraph (h) of AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013). If, during the inspection required by paragraph (g) of this AD, any horizontal stabilizer rear spar attach pin has P/N 180A1612–3 or 180A1612–4, prior to the accumulation of 56,000 total flight cycles on the pin, or within 3,000 flight cycles after May 20, 2013 (the effective date of AD 2013– 07–07), whichever occurs later, replace with a new attach pin having P/N 180A1612–7 or 180A1612–8, respectively, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737–55–1093, dated April 9, 2012.

(i) Retained Parts Installation Prohibition

This paragraph restates the requirements of paragraph (i)(2) of AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013). For airplanes having line numbers 3535 and subsequent: As of May 20, 2013 (the effective date of AD 2013–07–07), no person may install an attach pin of the horizontal stabilizer rear spar having P/N 180A1612–3 or 180A1612–4 on any airplane.

(j) Retained Terminating Action for AD 2004–05–19, Amendment 39 13514 (69 FR 10921, March 9, 2004; Corrected April 13, 2004 (69 FR 19313))

This paragraph restates the provisions of paragraph (j) of AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013). Accomplishment of the actions required by paragraphs (g) and (h) of this AD terminates the requirements of paragraphs (a), (b), (c), (d), and (e) of AD 2004–05–19, Amendment 39–13514 (69 FR 10921, March 9, 2004; corrected April 13, 2004 (69 FR 19313)), for the rear spar attach pins only.

(k) New Parts Installation Limitation

For airplanes having line numbers 1 through 3534 inclusive: As of the effective date of this AD, an attach pin of the horizontal stabilizer rear spar having P/N 180A1612–3 or 180A1612–4 may be installed on an airplane, provided it is replaced with an attach pin having P/N 180A1612–7 or 180A1612–8, as applicable, prior to the accumulation of 56,000 total flight cycles on the attach pin. The replacement must be
done in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737–55– 1093, dated April 9, 2012.


### 58985 Federal Register / Vol. 78, No. 186 / Wednesday, September 25, 2013 / Proposed Rules

(l) New Attach Pin Replacement

For airplanes having line numbers 1 through 3534 inclusive on which an attach pin of the horizontal stabilizer rear spar having P/N 180A1612–7 or 180A1612–8 has been replaced with an attach pin having P/
N 180A1612–3 or 180A1612–4 before the
effective date of this AD: Prior to the accumulation of 56,000 total flight cycles on the pin, or within 1,000 flight cycles on the airplane after the effective date of this AD, whichever occurs later, replace the attach pin having P/N 180A1612–3 or 180A1612–4 with an attach pin having P/N 180A1612–7 or 180A1612–8, as applicable, in accordance with the Accomplishment Instructions of Boeing Special Attention Service Bulletin 737–55–1093, dated April 9, 2012.

(m) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Seattle Aircraft Certification Office, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in paragraph (n)(1) of this AD. Information may
be emailed to 9-ANM-Seattle-ACO-AMOCRequests-faa.gov.

(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/ certificate holding district office.

(3) An AMOC that provides an acceptable level of safety may be used for any repair required by this AD if it is approved by the Boeing Commercial Airplanes ODA that has been authorized by the Manager, Seattle ACO, to make those findings. For a repair method to be approved, the repair must meet the certification basis of the airplane, and the approval must specifically refer to this AD.

(4) AMOCs approved previously in accordance with AD 2013–07–07, Amendment 39–17411 (78 FR 22182, April 15, 2013), are approved as AMOCs for the corresponding provisions of this AD.

(n) Related Information

(1) For more information about this AD, contact Nancy Marsh, Aerospace Engineer, Airframe Branch, ANM–120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057–3356; phone: 425–917–6440; fax: 425–917–6590;
email: Nancy.Marsh@faa.gov.

(2) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H–65, Seattle, Washington 98124–2207; telephone 206–544–5000, extension 1; fax 206–766–
5680; Internet https:// www.myboeingfleet.com. You may review copies of the referenced service information at the FAA, Transport Airplane Directorate, 1601 Lind Avenue SW., Renton, Washington. For information on the availability of this material at the FAA, call 425–227–1221. Issued in Renton, Washington, on September 17, 2013.
Ross Landes, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. 2013–23274 Filed 9–24–13; 8:45 am]

**BILLING CODE 4910–13–P**

**DELAWARE RIVER BASIN**
**COMMISSION**

**18 CFR Part 410**

**Proposed Amendments to the Water Quality Regulations, Water Code and**  **Comprehensive Plan To Update Water Quality Criteria for pH** 

**AGENCY :**  Delaware River Basin

Commission.

**ACTION :**  Proposed rule; notice of public hearing.

**SUMMARY :**  The Commission will hold a public hearing to receive comments on proposed amendments to the Commission’s Water Quality Regulations, Water Code and Comprehensive Plan to update stream quality objectives (also called ‘‘water quality criteria’’) for pH in interstate
tidal and non-tidal reaches of the main
stem Delaware River.

**DATES :**  The public hearing will be held at 2 p.m. on Thursday, October 24, 2013. The hearing will continue until all those wishing to testify have had an opportunity to do so. Written comments will be accepted and must be received by 5 p.m. on Thursday, November 21, 2013. For more information regarding the procedures for the hearing and comments, see Supplementary
Information.

**ADDRESSES :**  The public hearing will be
held in the Goddard Conference Room at the Commission’s office building located at 25 State Police Drive, West Trenton, NJ. As Internet mapping tools are inaccurate for this location, please use the driving directions posted on the
Commission’s Web site.

Oral Testimony and Written

Comments: Persons wishing to testify at the hearing are asked to register in advance by phoning Paula Schmitt at 609–883–9500, ext. 224. Written comments may be submitted as follows: If by email, to paula.schmitt@ drbc.state.nj.us; if by fax, to Commission Secretary at 609–883–9522; if by U.S. Mail, to Commission Secretary, DRBC, P.O. Box 7360, West Trenton, NJ 08628–0360; and if by overnight mail, to Commission Secretary, DRBC, 25 State Police Drive, West Trenton, NJ 08628–0360. Comments also may be delivered by hand at any time during the Commission’s regular office hours (Monday through Friday, 8:30 a.m. through 5 p.m. except on national holidays) until the close of the comment period at 5 p.m. on Thursday, November 21, 2013. In all cases, please include the commenter’s name, address and affiliation, if any, in the comment document and ‘‘pH Rulemaking’’ in the subject line.

**FOR FURTHER INFORMATION CONTACT :**  The rule text and a report entitled ‘‘pH
Criteria Revision Recommendations for
Interstate Waters of the Delaware River Basin: Basis & Background Document’’ (DRBC, March 2013) are available on the Commission’s Web site, www.drbc.net. Hard copies of the latter document may be obtained for the price of postage by contacting Ms. Paula Schmitt at 609– 883–9500, ext. 224. For questions about the technical basis for the rule, please
contact Dr. Erik Silldorff at 609–883– 9500 ext. 234. For queries about the rulemaking process, please contact
Pamela Bush at 609–477–7203.

**SUPPLEMENTARY INFORMATION :** 

Background. The Commission in 1967 assigned stream quality objectives (also called ‘‘criteria’’) for pH to all tidal and
non-tidal interstate streams in the Delaware River Basin (‘‘basin’’). Since that time, scientists’ understanding of
natural fluctuations in freshwater and saltwater pH levels has grown. Likewise, the development and application of pH criteria have evolved, while the Commission’s pH stream quality objectives have remained unchanged. Commission scientists in consultation with experts from DRBC member states and federal agencies have evaluated the pH criteria adopted by signatory states and recommended byfederal agencies over the past four-anda-half decades. They have concluded that in order to minimize regulatory
inconsistencies and better address natural pH cycles in the main stem Delaware River, two classes of revisions
to the Commission’s criteria for this shared interstate waterway should be considered. The first concerns the range of pH levels deemed to comprise the
numeric standard within the tidal and
non-tidal zones of the main stem and tidal portions of tributaries. The second
concerns excursions outside the standard range that are attributable to natural conditions. The proposed revisions were unanimously endorsed by the Commission’s Water Quality Advisory Committee (‘‘WQAC’’) in March 2009. The WQAC is a standing committee of stakeholders, including regulators, municipal and industrial dischargers, academicians and