antidegradation assessment section 401 water quality

Antidegradation Assessment – Section 401 Water Quality Certification

February 2020

ENBRIDGE ENERGY, LIMITED PARTNERSHIP ANTIDEGRADATION ASSESSMENT - SECTION 401 WATER QUALITY CERTIFICATION

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TABLE OF CONTENTS

1.0 INTRODUCTION ............................................................................................................... 1 2.0 PROJECT BACKGROUND .............................................................................................. 1 3.0 REGULATORY CONTEXT ............................................................................................... 2

3.1 ANTIDEGRADATION STANDARDS AND PROCEDURES .................................. 2 3.2 OVERVIEW OF ANTIDEGRADATION ASSESSMENT INFORMATION .............. 5

4.0 ANALYSIS OF ALTERNATIVES TO AVOID NET INCREASES IN LOADING OR OTHER CAUSES OF DEGRADATION ............................................................................ 5

5.0 EXISTING USES ............................................................................................................... 8 5.1 RECEIVING WATERS .......................................................................................... 9 5.2 RECEIVING WETLANDS ...................................................................................... 9 5.3 OUTSTANDING RESOURCE VALUE WATERS .................................................. 9 5.4 WATERS THAT SUPPORT NATURAL WILD RICE STANDS ........................... 10

5.4.1 Receiving Waters..................................................................................... 10 5.4.2 Downstream Waters ................................................................................ 11

6.0 EXISTING WATER QUALITY ........................................................................................ 13 6.1 PARAMETERS OF CONCERN ........................................................................... 13 6.2 WATER QUALITY DATA..................................................................................... 14 6.3 IMPAIRED WATERS ........................................................................................... 15

6.3.1 Receiving Waters..................................................................................... 15 6.3.2 Downstream Waters ................................................................................ 18

7.0 ANALYSIS OF PRUDENT AND FEASIBLE MEASURES TO MINIMIZE DEGRADATION ............................................................................................................. 18 7.1 PRUDENT AND FEASIBLE PREVENTION AND TREATMENT MEASURES

AT WATERBODIES ............................................................................................ 18 7.1.1 Selection of Pipeline Installation Crossing Method .................................. 19 7.1.2 Best Management Practices .................................................................... 27

7.2 PRUDENT AND FEASIBLE PREVENTION AND TREATMENT MEASURES AT WETLANDS ................................................................................................... 29 7.2.1 Selection of Pipeline Installation Crossing Method .................................. 30 7.2.2 Best Management Practices .................................................................... 32

7.3 RIPARIAN VEGETATION RESTORATION ........................................................ 38 7.4 COMPARISON OF LEAST DEGRADING PRUDENT AND FEASIBLE

MEASURES WITH EXISTING WATER QUALITY .............................................. 39 7.4.1 Overview of Potential Effects of the Least Degrading Prudent and

Feasible Alternative ................................................................................. 39 7.4.2 Anticipated Wetland Water Quality during Construction .......................... 46 7.4.3 Anticipated Waterbody Water Quality during Construction ...................... 48 7.4.4 Overview of Water Quality Effects Associated with an Inadvertent

Release ................................................................................................... 50 7.4.5 Water Quality Effects in Wetlands Associated with an Inadvertent

Release ................................................................................................... 55 7.4.6 Water Quality Effects in Waterbodies Associated with an Inadvertent

Release ................................................................................................... 55 7.4.7 Expected Economic Conditions and Social Services Resulting From

the Project................................................................................................ 55 8.0 ANTIDEGRADATION ASSESSMENT SUMMARY ........................................................ 56

8.1 PROTECTING EXISTING USES ........................................................................ 56 8.1.1 Water Quality Effects ............................................................................... 56


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8.1.2 Compensatory Mitigation for Physical Alteration of Wetlands ................. 57 8.2 PROTECTING BENEFICIAL USES .................................................................... 57 8.3 PROTECTING SURFACE WATERS OF HIGH QUALITY .................................. 57 8.4 PROTECTING RESTRICTED OUTSTANDING RESOURCE VALUE

WATERS ............................................................................................................. 58 9.0 REFERENCES ................................................................................................................ 60

TABLES

Table 5.4-1 Receiving Waters for the Line 3 Replacement Project that Support Natural Wild Rice Stands ................................................................................................... 12

Table 6.1-1 Parameters associated with Impairments ............................................................. 13 Table 6.1-2 Parameters of Concern ......................................................................................... 14 Table 6.3.1-1 Receiving Waters with 303(d) Impairments Crossed by the Line 3

Replacement Project ............................................................................................. 15 Table 6.3.2-1 303(d) Impaired Waterbodies with Parameters of Concern Downstream of

Waterbodies Crossed by the Line 3 Replacement Project ................................... 18 Table 7.1.1-1 Proposed Waterbody Crossing Construction Method Summary .......................... 19 Table 7.1.1-2 Summary of Hydrofracture Analysis Reports for Proposed HDD Crossings ........ 24 Table 7.1.1-3 Alternative Crossing Methods for Proposed Horizontal Directional Drill

Locations South of the Clearbrook Terminal......................................................... 26 Table 7.1.1-4 Alternative Crossing Method Construction Impact Comparison for the

Mississippi River Crossing at MP 1069.6 .............................................................. 27 Table 7.2.1-1 Proposed Wetland Crossing Construction Method Summary .............................. 30 Table 7.4.3-1 TSS Concentrations Measured at Dry Crossings on Segment 18 ....................... 49

FIGURES

Figure 2.0-1 Line 3 Replacement Project Overview Map through Fond du Lac Reservation ..... 3 Figure 2.0-2 Line 3 Replacement Project Overview Map ............................................................ 4 Figure 6.3-1 River Nutrient Regions Crossed by the Project .................................................... 17 Figure 7.2.2-1 Erosion Prevention and Sediment Control Installation Guidelines Decision

Tree: In-Wetland Scenarios .................................................................................. 37

ATTACHMENTS

Attachment A Minnesota Public Utilities Commission Certificate of Need Proceedings, Findings and Conclusions regarding “Important Economic or Social Changes” from the September 5, 2018 Minnesota Public Utilities Commission Order Granting A Certificate of Need for the Project

Attachment B Minnesota Public Utilities Commission Route Permit Proceedings, Selected Findings and Conclusions from the October 26, 2018 Minnesota Public Utilities Commission Route Permit Order regarding the Natural Environment, Including Waters, and Natural Resources

Attachment C Receiving Waters Tables

• Table C-1 Waterbodies Crossed by Mainline Construction

• Table C-2 Waterbodies Crossed by Access Roads/Haul Routes


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Attachment D Wetland Impact Tables

• Table D-1 Mainline Wetland Impact Table

• Table D-2 Access Road/Haul Route Wetland Impact Table

Attachment E Downstream Waters That Support Natural Wild Rice Stands

Attachment F Water Quality Data Received from the Minnesota Pollution Control Agency

Attachment G Anticipated Water Quality - Parameters of Concern and Waterbody Crossing Justifications

Attachment H Environmental Protection Plan

Attachment I Blasting Plan

Attachment J Winter Construction Plan

Attachment K Hydrofracture Analyses

Attachment L Drilling Mud Additives Information

Attachment M Site-Specific HDD Inadvertent Release Response Plans

Attachment N Post-Construction Wetland and Waterbody Monitoring Plan

Attachment O Summary of Riparian Information at Waterbody Crossings

Attachment P L3R Compensatory Wetland Mitigation Plan


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ACRONYMS AND ABBREVIATIONS

µm micrometer Antidegradation Rules Minnesota Administrative Rules parts 7050.0250 through 7050.0325 BMPs best management practices BOD5 biochemical oxygen demand BWSR Minnesota Board of Water & Soil Resources CFR Code of Federal Regulations CWA Clean Water Act Designated Route Minnesota Public Utilities Commission Designated Route DOC-EERA Minnesota Department of Commerce, Energy Environmental Review

and Analysis EI Environmental Inspector EIS Environmental Impact Statement Enbridge Enbridge Energy, Limited Partnership EPA U.S. Environmental Protection Agency EPP Environmental Protection Plan FdL Fond du Lac Band FdL Section 401 WQC Section 401 Water Quality Certification for the portion of the Line 3

Replacement Project inside of the Fond du Lac Band Reservation boundary

FEIS Final Environmental Impact Statement FMP Fen Management Plan Gully 30 fen Gully 30 calcareous fen HDD horizontal directional drill INS Invasive and Noxious Species IRRPs Inadvertent Release Response Plans L3R or Project Line 3 Replacement Project MDNR Minnesota Department of Natural Resources mg/L milligrams per liter Minnesota Rules Minnesota Administrative Rules MP milepost MPCA Minnesota Pollution Control Agency MPCA Section 401 WQC Section 401 Water Quality Certification for the portion of the Line 3

Replacement Project outside of the Fond du Lac Band Reservation boundary

MPUC Minnesota Public Utilities Commission MPUC Applications Certificate of need and a route permit applications MPUC FEIS Order May 1, 2018 written order from the MPUC finding the revised FEIS

adequate MPUC CN Order September 5, 2018 written order from the MPUC granting the

certificate of need MPUC RP Order October 26, 2018 written route permit order issued by the MPUC NPDES National Pollutant Discharge Elimination System OHWM ordinary high-water mark ORVW Outstanding Resource Value Waters POC parameters of concern FdL Reservation Fond du Lac Band Reservation RNR River Nutrient Regions RSA Route Segment Alternative


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SDS State Disposal System Section 401 WQC Assessment

an Antidegradation Assessment in support of the MPCA Section 401 WQC

Section 404 Project Application

U.S. Army Corps of Engineers permit application for the Line 3 Replacement Project

Segment 18 the 13-mile segment of the Line 3 Replacement Project in Wisconsin SONAR Statement of Need and Reasonableness SPCC Spill Prevention, Containment, and Control SWPPP Stormwater Pollution Prevention Plan TALU tiered aquatic life use TSS total suspended solids USACE U.S. Army Corps of Engineers WQC water quality certifications


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1.0 INTRODUCTION

On September 21, 2018, Enbridge Energy, Limited Partnership (“Enbridge”) applied to the St. Paul District, U.S. Army Corps of Engineers (“USACE”) for an Individual Permit under Section 404 of the Clean Water Act (“CWA”) for discharges of dredged or fill material into waters of the United States, including wetlands, in connection with the Line 3 Replacement Project (“L3R” or “Project”). This USACE permit application is referred to herein as the “Section 404 Project Application.”

The Section 404 Project Application requires three water quality certifications (“WQC”) under Section 401 of the CWA: (1) a Section 401 WQC from the North Dakota Department of Health (“NDDH”) for the portion of the Project (0.6 mile) from the Red River mainline valve in North Dakota to the North Dakota/Minnesota border (“NDDH Section 401 WQC”); (2) a Section 401 WQC from the Fond du Lac Band of Lake Superior Chippewa (“FdL”) for the portion of the Project within the exterior boundaries of the Fond du Lac Band Reservation (“FdL Reservation”) (“FdL Section 401 WQC”); and (3) a Section 401 WQC from the Minnesota Pollution Control Agency (“MPCA”) for the portion of the Project in Minnesota outside the exterior boundaries of the Reservation (“MPCA Section 401 WQC”).

On January 31, 2019 NDDH issued the NDDH Section 401 WQC having found reasonable assurance that the portion of the Project in North Dakota complies with the Standards of Quality for Waters of the State, N.D. Admin. Code, chapter 33-16-02.1. On April 15, 2019 FdL issued the FdL Section 401 WQC having found reasonable assurance that the activities associated with the portion of the Project within the exterior boundaries of the FdL Reservation will comply with the Fond du Lac Band of Lake Superior Chippewa Water Quality Standards of the Fond du Lac Reservation, Ordinance #12/98, as amended.

The MPCA Section 401 WQC requires antidegradation review under Minnesota Administrative Rules (“Minnesota Rules”) parts 7050.0250 to 7050.0335. The purpose of an antidegradation review is to achieve and maintain the highest possible quality in surface waters1 of the state (Minnesota Rules, part 7050.0250). This document includes an Antidegradation Assessment in support of the MPCA Section 401 WQC, hereafter referred to as the “Section 401 WQC Assessment.”

2.0 PROJECT BACKGROUND

The Project is a pipeline integrity- and maintenance-driven program designed to address identified mechanical integrity deficiencies on the existing Line 3 pipeline and to return the pipeline to the operating capabilities for which it was designed. L3R consists of approximately 355 miles of new 36-inch-diameter pipeline traversing the states of North Dakota, Minnesota, and Wisconsin, and terminating at the existing Enbridge Superior terminal facility near Superior, Wisconsin. This Section 401 WQC Assessment includes replacement of the existing 34-inch-diameter Line 3 pipeline with 36-inch2-diameter pipeline and associated facilities in Minnesota outside the exterior

1 See Minnesota Rules, part 7050.0130, Subp. 6 which states: “’Surface waters’ means waters of the state

excluding groundwater as defined in Minnesota Statutes, section 115.01, subdivision 6.” 2 36-inch-diameter steel pipeline is a more standard pipeline than 34-inch in the industry and among the Enbridge

Mainline System. The decision to replace with 36-inch-diameter pipeline makes pipe, pipefitting, valves, and maintenance equipment more readily available. A 36-inch pipeline is more energy efficient than a 34-inch pipeline.


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boundaries of the FdL Reservation (see Figure 2.0-1). Enbridge’s route generally follows the existing Line 3 pipeline along the Enbridge Mainline System right-of-way from the North Dakota/Minnesota border in Kittson County to the Clearbrook Terminal in Clearwater County. Next, L3R turns south from Clearbrook to generally follow an existing third-party crude oil pipeline right-of-way to Hubbard County. The route then turns east to generally follow other existing electric transmission lines until it rejoins the Enbridge Mainline System right-of-way in St. Louis County, through the FdL Reservation to the Minnesota/Wisconsin border in Carlton County (Figure 2.0-2).

3.0 REGULATORY CONTEXT

3.1 ANTIDEGRADATION STANDARDS AND PROCEDURES

Minnesota Rules parts 7050.0250 through 7050.0335 (“Antidegradation Rules”) include multiple antidegradation standards and procedures. The applicability of these specific standards and procedures is determined by the nature of the proposed activity and the type of “control document” required to authorize that activity. The term “control document” means any “authorization issued by the commissioner that specifies water pollution control conditions under which a regulated activity is allowed to operate” (Minnesota Rules, part 7050.0255, subpart 10). Enbridge is applying for multiple authorizations that require antidegradation review under Antidegradation Rules:

• the Section 401 WQC (Minnesota Rules, part 7050.0285);

• an Individual National Pollutant Discharge Elimination System (“NPDES”)/State Disposal System (“SDS”) Industrial Wastewater Permit to conduct discharge of waters used for buoyancy control during pipeline installation, and to test the structural integrity of the pipeline (Minnesota Rules, part 7050.0280); and

• coverage under the NPDES/SDS Construction Stormwater General Permit (MNR100001) (Minnesota Rules 7050.0295).

Concurrent with the submittal of this Section 401 WQC Assessment, Enbridge submitted an Antidegradation Assessment in support of the Individual NPDES/SDS Industrial Wastewater permit application to conduct discharge of waters used to test the structural integrity of the pipeline.

For construction stormwater discharges, Enbridge will request coverage under the NPDES/SDS Construction Stormwater General Permit (MNR100001, issuance date: August 1, 2018, expiration date: July 31, 2023). MPCA conducted an antidegradation review during development of the Minnesota NPDES/SDS Construction Stormwater General Permit to develop permit conditions that will ensure that antidegradation standards are satisfied. The final antidegradation determination stated that issuing the general permit will achieve applicable antidegradation standards. No further Antidegradation Assessment is required for the Project because Enbridge will certify that the construction stormwater general permit conditions can and will be met (Minnesota Rules, part 7050.0295, Subp. 6.).


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Figure 2.0-1 Line 3 Replacement Project Overview Map through Fond du Lac Reservation


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Figure 2.0-2 Line 3 Replacement Project Overview Map


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3.2 OVERVIEW OF ANTIDEGRADATION ASSESSMENT INFORMATION

In this Section 401 WQC Assessment, Enbridge provides the information required by the Antidegradation Rules (Minnesota Rules, 7050.0285, Subp. 2) as follows:

• Enbridge analyzes alternatives to avoid net increases in loading or other causes of degradation3 through prudent and feasible prevention, treatment or loading offsets (Minnesota Rules 7050.0280, Subp. 2A) by review of the DOC-EERA EIS and MPUC certificate of need and route permit decisions (Section 4.0).

• Enbridge presents the existing uses and water quality of receiving4 and downstream5 surface waters associated with the Project (Minnesota Rules 7050.0280, Subp. 2B) (Sections 5.0 and 6.0).

• Enbridge analyzes the prudent6 and feasible7 prevention and treatment measures to minimize degradation through the assessment of the Project construction techniques and other prevention measures (i.e., best management practices [“BMPs”]) (Section 7.0).

Section 8.0 summarizes how the Project will protect existing uses (Minnesota Rules 7050.0265, Subp. 2) (Section 8.1), proposes compensatory mitigation to preserve existing uses (Minnesota Rules 7050.0265, Subp. 3) (Section 8.1.2) and how the Project will protect beneficial uses (Minnesota Rules 7050.0265, Subp. 4) (Section 8.2). Enbridge also summarizes how the Project will protect surface waters of high quality (Minnesota Rules 7050.0265, Subp. 4) (Section 8.3), and restricted outstanding resource value waters (“ORVWs”) (Minnesota Rules 7050.0265, Subp. 6) (Section 8.4). The Project does not cross any prohibited ORVWs (Minnesota Rules 7050.0265, Subp. 7).

4.0 ANALYSIS OF ALTERNATIVES TO AVOID NET INCREASES IN LOADING OR OTHER CAUSES OF DEGRADATION

The Antidegradation Rules require the MPCA to consider alternatives that avoid net increases in loading or other causes of degradation through prudent and feasible prevention, treatment, or loading offsets (Minnesota Rules part 7050.0280 subpart 2):

3 “Degradation” or “degrade” means a measurable change to existing water quality made or induced by human

activity resulting in diminished chemical, physical, biological, or radiological qualities of surface waters (Minnesota Rules 7050.0255, Subp. 11. “Measurable change” means the practical ability to detect a variation in water quality, taking into account limitations in analytical technique and sample variability (Minnesota Rules 7050.0255, Subp. 24).

4 Receiving waters include surface waters where construction activities are proposed, such as crossing locations, or water appropriation or discharge.

5 Downstream waters include the first hydrologically connected surface water to a surface water where Project activities are proposed (e.g., crossing location).

6 “Prudent alternative” means a pollution control alternative selected with care and sound judgement (Minnesota Rules 7050.0255, Subp. 34).

7 “Feasible alternative” means a pollution control alternative that is consistent with sound engineering and environmental practices, affordable, and legal and that has supportive governance that can be successfully put into practice to accomplish the task (Minnesota Rules 7050.0255, Subp. 17).


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A feasible alternative is defined as “a pollution control alternative that is consistent with sound engineering and environmental practices, affordable, and legal, and that has supportive governance that can be successfully put into place to accomplish the task.” (Minnesota Rules part 7050.0255 subpart 17)

A prudent alternative is defined as “a pollution control alternative selected with care and sound judgement” (Minnesota Rules part 7050.0255 subpart 34)

Enbridge applied for a certificate of need and a route permit (“MPUC Applications”) from the Minnesota Public Utilities Commission (“MPUC”) to construct and operate L3R on April 24, 2015. The MPUC asked the Minnesota Department of Commerce, Energy Environmental Review and Analysis (“DOC-EERA”) staff to prepare an Environmental Impact Statement (“EIS”) in cooperation with the Minnesota Department of Natural Resources (“MDNR”) and MPCA to facilitate the review of Enbridge’s certificate of need and route permit applications for L3R in accordance with Minnesota Rules Chapter 4410. DOC-EERA issued the draft EIS on May 15, 2017 and the final EIS (“FEIS”) on August 17, 2017.8 The FEIS considered numerous certificate of need alternatives to the Project, including, but not limited to, the no action alternative, System Alternative SA-04, transportation by rail, transportation by truck and a smaller diameter pipeline. The FEIS also considered four route permit alternatives to the Project’s Preferred Route between Clearbrook and Carlton, RA-03(AM), RA-06, RA-07 and RA-08, and twenty-four Route Segment Alternatives (“RSAs”). On December 7, 2017, the MPUC deemed the FEIS inadequate solely on the basis of four specific and narrow issues, and a revised FEIS was published on February 12, 2018. On May 1, 2018, the MPUC issued a written order finding the revised FEIS adequate (“MPUC FEIS Order”).

At the conclusion of contested case proceedings on the MPUC Applications presided over by an administrative law judge, which included sixteen (16) public hearings resulting in over 2,600 pages of public hearing transcripts, the MPUC heard oral arguments and deliberated on the merits of the MPUC Applications on June 18, 19, 26, 27, and 28, 2018. On June 28, 2018, the MPUC voted to grant a certificate of need for the Project, subject to certificate of need modifications. On September 5, 2018, the MPUC issued a written order granting the certificate of need as modified and requiring filings (“MPUC CN Order”).

The MPUC CN Order considered factors set forth in statute (Minnesota Statutes, section 216B.243, subd. 3) and rule (Minn. Rules, Chapter 7853) to evaluate the need for the Project. In particular, Minn. Rules, part 7853.0130 directs the MPUC to issue a certificate of need for a proposed large petroleum pipeline such as the Project when the applicant satisfies the following four factors: (1) the probable result of denial would adversely affect the future adequacy, reliability, or efficiency of energy supply to the applicant, to the applicant’s customers, or to the people of Minnesota and neighboring states, considering five enumerated sub-factors; (2) a more reasonable and prudent alternative to the proposed facility has not been demonstrated by a preponderance of the evidence on the record by parties or persons other than the applicant, considering four enumerated sub-factors, including the effects upon the natural and socioeconomic environments; (3) the consequences to society of granting the certificate of need are more favorable than the consequences of denying the certificate, considering four enumerated sub-factors, also including the effects upon the natural and socioeconomic environments; and (4) it has not been demonstrated on the record that the design, construction,

8 The L3R draft EIS and FEIS are available on the Minnesota Department of Commerce website at:

https://mn.gov/commerce/energyfacilities/line3/.

https://mn.gov/commerce/energyfacilities/line3/


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or operation of the proposed facility will fail to comply with those relevant policies, rules, and regulations of other state and federal agencies and local governments.

Attachment A highlights findings and conclusions from the September 5, 2018, MPUC CN Order [including page citations] that describe those “important economic or social changes” (Minnesota Rules, part 7850.0265, subp. 5B) resulting from the Project that the MPUC relied on in part in approving the certificate of need for the Project, contingent on suitable modifications.

On June 28, 2018, the MPUC also voted to grant a route permit for the Project’s Preferred Route, including RSA-05 and RSA-22 through the FdL Reservation with permission of FdL. On August 31, 2018, Enbridge and FdL reached an agreement that allows Enbridge to construct the Project along RSA-22 through the FdL Reservation in northern Minnesota. The MPUC issued a written route permit order on October 26, 2018 (“MPUC RP Order”) identifying the Project’s Preferred Route inclusive of RSA-05 and RSA-22 as the MPUC Designated Route (hereafter referred to as the “Designated Route” or “Project”). The Project is a 750-foot-wide corridor, which allows for minor adjustments to the pipeline alignment and permanent right-of-way within the Project (see Figure 2.0-2).

In selecting a route, the MPUC must consider each proposed route’s characteristics and potential consequences—including methods to minimize or mitigate those consequences—to identify the route that minimizes harm to people and the environment (Minnesota Rules, part 7852.1900, subp.2). Specifically, Minnesota Rules, part 7852.1900, subp. 3, directs the MPUC to consider the following factors when evaluating route alternatives:

A. human settlement, existence and density of populated areas, existing and planned future land use, and management plans;

B. the natural environment, public and designated lands, including but not limited to natural areas, wildlife habitat, water, and recreational lands (emphasis added);

C. lands of historical, archaeological, and cultural significance;

D. economies within the route, including agricultural, commercial or industrial, forestry, recreational, and mining operations;

E. pipeline cost and accessibility;

F. use of existing rights-of-way and right-of-way sharing or paralleling;

G. natural resources and features (emphasis added);

H. the extent to which human or environmental effects are subject to mitigation by regulatory control and by application of the permit conditions contained in part 7852.3400 for pipeline right-of-way preparation, construction, cleanup, and restoration practices;

I. cumulative potential effects of related or anticipated future pipeline construction; and

J. the relevant applicable policies, rules, and regulations of other state and federal agencies, and local government land use laws including ordinances adopted under Minnesota Statutes, section 299J.05 [establishing the minimum distance between a pipeline and the


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edge of an easement], relating to the location, design, construction, or operation of the proposed pipeline and associated facilities.

Attachment B highlights selected findings and conclusions from the October 26, 2018, MPUC RP Order [including page citations] regarding the natural environment, including waters, and natural resources.

On June 3, 2019, the Minnesota Court of Appeals reversed the MPUC FEIS Order upon determining that the failure to address the potential impacts of an oil spill into the Lake Superior Watershed constituted an inadequacy in the FEIS. On October 1, 2019, the MPUC met to consider the matter. On October 8, 2019, MPUC issued a written order finding the FEIS inadequate on remand and requesting DOC-EERA to revise the FEIS to include an analysis of the potential impact of an oil spill into the Lake Superior Watershed consistent with the Court of Appeals’ June 3 decision, and to submit a revised final EIS to MPUC within 60 days.

On December 9, 2019, the DOC-EERA published the Second Revised FEIS, including an analysis of the impact of an oil spill into the Lake Superior Watershed. The MPUC accepted comments regarding the Second Revised FEIS and its certificate of need and route permit decisions through January 31, 2020. On February 3, 2020, the MPUC found that the Second Revised FEIS was adequate and reaffirmed its previous certificate of need and route permit orders with a minor change related to the public safety escrow condition within the route permit. The MPUC’s written order(s) are forthcoming.9

While the statutory language governing the MPUC findings differs slightly from the language of the Antidegradation Rules, the certificate of need System Alternatives and route permit alternatives and RSAs considered in the EIS and rejected by MPUC in the September 5, 2018 MPUC CN Order and in the October 26, 2018 RP Order individually and collectively, are not “feasible” alternatives to avoid degradation of water quality because they lack “supportive governance that can be successfully put into practice to accomplish the task” (7050. 0255, subp. 17).

5.0 EXISTING USES

The following sections present the existing uses and water quality determination methods for receiving and downstream surface waters associated with the Project. Receiving and downstream waters, like all waters of the state, are classified to protect specific beneficial uses. For this Section 401 WQC Assessment, the designated beneficial uses established in Minnesota Rules parts 7050.0440 thru 7050.0470 are considered to be existing uses.

One undesignated existing use was also identified: natural wild rice stands. Minnesota Rules part 7050.0470 subpart 1 designates some surface waters as wild rice waters. None of the receiving or downstream waters associated with the Project is listed as a wild rice water under Minnesota Rules part 7050.0470. However, Enbridge did identify several receiving waters and appropriation sources that support natural wild rice stands, as well as wild rice waters located downstream of waterbody crossings (see Section 5.4).

9 Under Minnesota Statutes, section 116D.04. subd. 2b, a final governmental decision may not be made to grant a

permit or approve a project until the environmental impact statement has been determined adequate.


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5.1 RECEIVING WATERS

Attachment C identifies the non-wetland surface waters across which the pipeline or access road/haul routes will be installed, where beaver dams are proposed to be removed, and/or where water appropriation activities are proposed and lists their beneficial use classifications and the proposed crossing method (see Section 7.1).

The MPCA adopted changes to its water quality standards, which the U.S. Environmental Protection Agency (“EPA”) approved in June 2018, that establish a tiered aquatic life use (“TALU”) framework for watercourses (Minnesota Rule Chapters 7050 and 7052). The TALU framework is a significant revision and will enhance the protection and maintenance of state water resources. Currently none of the Project’s receiving waters has a proposed use designations under the new framework.

5.2 RECEIVING WETLANDS

Attachment D identifies the wetlands that will be physically altered by installation of the pipeline, removal of beaver dams, or access roads/haul routes and indicates the proposed crossing method (see Section 7.2). The wetlands crossed by the Project are unlisted, and are therefore classified as follows (Minnesota Rules 7050.0425 and 7050.0186):

• Permit the propagation and maintenance of a healthy community of aquatic and terrestrial species indigenous to wetlands, and their habitats. Wetlands also add to the biological diversity of the landscape. These waters shall be suitable for boating and other forms of aquatic recreation for which the wetland may be usable (Class 2D, Minnesota Rules 7050.0221, Subp. 6);

• Permit their use for general industrial purposes, except for food processing, with only a moderate degree of treatment (Class 3D, Minnesota Rules 7050.0223, Subp. 5);

• Permit their use for irrigation and by wildlife and livestock without inhibition or injurious effects and be suitable for erosion control, groundwater recharge, low flow augmentation, storm water retention, and stream sedimentation (Class 4C, Minnesota Rules 7050.0224, Subp. 4);

• Suitable for aesthetic enjoyment of scenery, to avoid any interference with navigation or damaging effects on property (Class 5, Minnesota Rules 7050.0225, Subp. 2); and

• Any additional beneficial uses under other jurisdictions or any standards deemed necessary by the MPCA for the protection of this class, consistent with legal limitations (Class 6, Minnesota Rules 7050.0226, Subp. 2).

5.3 OUTSTANDING RESOURCE VALUE WATERS

The Project will not cross any prohibited Outstanding Resource Value Waters (“ORVWs”).

The Project will cross two restricted ORVWs: the Mississippi River (crossed twice at mileposts (“MP”) 941.0 and 1069.9) and the Gully 30 calcareous fen (“Gully 30 Fen”). A separate Fen Management Plan (“FMP”) has been developed for the Gully 30 Fen crossing, which details the


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site-specific construction procedures for this crossing. MDNR must approve the Gully 30 FMP before construction begins at this crossing (Minnesota Rules, part 8420.0935, subp. 4).

5.4 WATERS THAT SUPPORT NATURAL WILD RICE STANDS

Wild rice is an annual emergent grass that re-establishes itself from seed each spring. Wild rice, or Manoomin, is a significant resource to the Ojibwe Tribal nations, not only for subsistence but also in the identity of the Tribes. Wild rice harvesting is also open to Minnesota residents and nonresidents and is licensed and managed by the MDNR. Enbridge used desktop and field survey methods to identify waters that support natural wild rice stands that could potentially be affected by Project construction.

5.4.1 Receiving Waters

To identify whether receiving waters are known to support natural wild rice stands, Enbridge accessed the MPCA database titled MPCA Draft List of Wild Rice Waters (MPCA, 2016). The MPCA states that this database includes waterbodies that the MDNR or other stakeholders have identified as supporting natural wild rice stands, including information from the following sources (MPCA, 2016).

• MDNR wild rice report titled Natural Wild Rice in Minnesota - A Wild Rice Study, submitted to the Minnesota Legislature in 2008;

• MDNR Wild Rice Harvester Survey conducted in 2006;

• List of significant wild rice resources throughout compiled by the Minnesota Interagency Wild Rice Management Workgroup;

• MDNR's Minnesota Biological Survey program database of surveyed sites for wild rice waters;

• MPCA 2013 “Call for Data” on wild rice stands with estimated wild rice acreage of greater than one acre;

• MDNR Aquatic Plant Management permitting program database multi-year wild rice permit information;

• MPCA Biomonitoring field sample site database wild rice records from 1999 to 2014;

• The 1854 Treaty Authority list of wild rice waters within the ceded territory;

• Minnesota Rules 7050.0470 which contains the list of wild rice waters specifically identified in the rule in 2016;

• University of Minnesota/MPCA (2013) 2011, 2012, and 2013 field surveys of waterbodies that included estimated plant coverage at the sampling sites; and

• Permittee Monitoring (MPCA) results of multi-year field surveys of selected waters in northeastern Minnesota for water quality and wild rice data.


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Enbridge also accessed the MDNR Wild Rice waters list (MDNR, 2020) and the 2007 Harvester’s survey (Norgaard et al., 2007).

Enbridge subsequently conducted wild rice surveys in 2018 and 2019 at Project waterbody crossings and water appropriation sources near the proposed appropriation point. Table 5.4-1 identifies receiving waters that Enbridge has identified as supporting natural wild rice stands, and the source of the information. Enbridge also included three lakes in Table 5.4-1 where the Project crosses wetlands that occur within the boundaries of the MDNR 2020 Wild Rice Lakes digital data.

5.4.2 Downstream Waters

Enbridge used desktop methods to identify downstream waters that are known to support natural wild rice stands. The desktop study screened waters downstream of each non-wetland waterbody crossing listed in Attachment C-1 and located within the same HUC-8 watershed as the crossing.

Any sediment disturbed by crossing construction would not be expected to travel further than the first lake downstream of a crossing, so the desktop evaluation identified the first downstream lake, and determined whether it is listed on the MPCA Draft List of Wild Rice Waters (MPCA, 2016), the MDNR Wild Rice Waters List (MDNR, 2020), or the 2007 Harvester’s survey (Norgaard et al., 2007). The evaluation also identified cases where a river reach downstream of a crossing is listed and where there is no lake located between the crossing and the listed reach. Results of this evaluation are provided in Attachment E.


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TABLE 5.4-1 Receiving Waters for the Line 3 Replacement Project that Support Natural Wild Rice Stands

Waterbody Name Milepost County MPCA draft wild rice waters lista

DNR wild rice waters listb

2007 Harvester’s

surveyc

Wild Rice Observed during Environmental

Field Surveys Crossing Method

Water Appropriation

Location

Middle River 835.9 Marshall no no no yes d HDD yes

Red Lake River 864.3 Pennington no no no yes HDD yes

Clearwater River 875.4 Red Lake no no no yes HDD yes

Lost River 885.8 Red Lake no no no yes Dry Crossing no

Clearwater River 922.2 Clearwater no e no yes yes HDD yes

Mississippi River 941.1 Clearwater no e no yes no HDD yes

Island Lake 961.7 Hubbard no yes no yes Not Crossed yes f

Hay Creek 963.7 Hubbard yes yes yes yes HDD no

Shell River 983.7 Hubbard no e no yes yes HDD yes

Portage Lake g 967.7 Hubbard yes yes no yes Standard Wetland Open Cut

no

Shell River 985.4 Hubbard no e no yes yes HDD yes

Shell River 991.2 Wadena no e no no yes HDD yes

Crow Wing River 993.3 Wadena yes no yes yes HDD yes

Pine River 1017.4 Cass yes no yes yes HDD yes

Peterson Lake g 1028.6 Cass yes yes no no Standard Wetland Open Cut

no

Lake George 1036.9 Cass yes yes yes yes Not Crossed yes

Moose River 1055.7 Aitkin no no no yes Access Road no

Moose Lake g 1056.6 Aitkin yes yes yes yes Push-Pull no

St. Louis River 1094.2 St. Louis no no yes no Not Crossed yes a MPCA, 2016 based on crossing reach. b MDNR, 2020 based on crossing reach. c Norgaard et al., 2007 based on county where the Project crossing is located. d Wild rice observed only during 2018 survey. e MPCA listed wild rice waters exist downstream of this crossing f Contingency water appropriation location only. g The Project crosses wetlands that are within the MDNR 2020 wild rice water digital data boundary of these lakes.


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6.0 EXISTING WATER QUALITY

6.1 PARAMETERS OF CONCERN

The first step in determining existing water quality is to determine the parameters of concern (“POC”) because this Section 401 WQC Assessment is limited to the relevant POC. As defined in the Statement of Need and Reasonableness (“SONAR”) for the Antidegradation Rules (SONAR at p 88), POC are pollutants which:

• are reasonably expected in a discharge or as a result of a proposed activity;

• are anticipated to cause degradation (a measurable change to existing water quality made or induced by human activity resulting in diminished conditions of surface waters);

• have numeric or narrative standards; and

• present the greatest risk of degradation.

The SONAR for the Antidegradation Rules indicates that the MPCA “will ultimately decide which parameters will be reviewed” (SONAR at p 90). Enbridge requested and the MPCA provided a list of POC in a comment letter dated March 14, 2019. MPCA’s requested POC for this Section 401 WQC Assessment are as follows: total suspended solids (“TSS”); mercury; dissolved oxygen (“DO”); phosphorus; river eutrophication; and parameters “for which … waters in the area are…listed as impaired.”

Parameters associated with river eutrophication are specified in Minnesota Rules numeric Class 2A, 2Bd, and 2B standards: phosphorus, chlorophyll-a, and biochemical oxygen demand (“BOD5”). For Class 2A rivers, DO flux is also a eutrophication parameter. In addition to these numeric standards, Minnesota Rules contain narrative river eutrophication standards.

In order to identify any additional POC “for which…waters in the area are…listed as impaired,” Enbridge identified all 2018 impairments in receiving and downstream waters (see Section 6.3). Table 6.1-1 lists all 2018 impairments in receiving and downstream waters, identifies the parameters associated with the impairments, and describes how they are addressed in this Section 401 WQC Assessment.

The POC determined by the processes described above, and their applicable water quality standards are listed in Table 6.1-2.

Table 6.1-1 Parameters associated with Impairments

Impairment Associated parameter(s) Coverage in Antidegradation Assessment

Aquatic macroinvertebrate bioassessment

TSS Aquatic macroinvertebrates bioassessment is included as a POC where the 2018 MPCA Total Maximum Daily Load (“TMDL”) 303(d) List indicates that TSS is a stressor

Chlorpyrifos Chlorpyrifos Chlorpyrifos is an insecticide. The Project will not use

insecticides, therefore chlorpyrifos is not included as a POC.

DO DO DO is included as a POC

Escherichia coli (“E. coli”) E. coli E. coli is associated with animal feces. The Project will not

introduce animal feces therefore E. coli is not included as a POC.


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Table 6.1-1 Parameters associated with Impairments

Impairment Associated parameter(s) Coverage in Antidegradation Assessment

Fecal coliform Fecal coliform Fecal coliform is typically associated with sewage. The Project

will not introduce sewage; therefore, fecal coliform is not included as a POC.

Fishes bioassessment TSS Fishes bioassessment is included as a POC where the 2018

MPCA TMDL 303(d) List indicates that TSS is a stressor

Mercury in fish tissue Mercury Included as POC at the request of MPCA

Polychlorinated biphenyl (“PCB”) in fish tissue

PCBs The Project will not involve use of PCBs; therefore, they are not included as a POC.

Turbidity/TSS TSS TSS is included as a POC

Table 6.1-2 Parameters of Concern

Parameters of Concern for Surface Waters Applicable Standards

TSS Class 2 numeric standards; narrative prohibition on nuisance conditions (Minnesota Rules 7050.0210, Subp. 2)

Mercury Class 1a and Class 2 numeric standards

Phosphorus Class 2 numeric standards

DO Class 2 numeric standards

Parameters of Concern for Waterbodies Only Applicable Standards

River eutrophication Class 2 numeric and narrative standards

a Class 1 waters are for domestic consumption, which includes all waters of the state that are or may be used as a source of supply for drinking, culinary or food processing, or other domestic purposes and for which quality control is or may be necessary to protect the public health, safety, or welfare (Minnesota Rules 7050.0140, Subp. 2.)

6.2 WATER QUALITY DATA

Enbridge used publicly available MPCA water quality data as its primary source to determine the existing water quality for receiving and downstream waters associated with the Project, which is the highest priority method for evaluating water quality (Minnesota Rules, 7050.0260, Subp. 1A). See Attachment F for the water quality data provided by the MPCA.

Enbridge characterized existing water quality in order to establish which waters are high quality waters according to the definition in Minnesota Rules, Part 7050.0255 subpart 21. An impaired water “does not meet applicable water quality standards or fully support applicable beneficial uses, due in whole or in part to water pollution from point or nonpoint sources, or any combination thereof” (Minnesota Rules, 7050.0150, Subp. 4O). Enbridge has evaluated all receiving waters to identify those that have been listed as impaired by the MPCA.

Enbridge characterized existing water quality of waters without relevant impairments (see Table 6.1-1) using the central tendency, more specifically the 95 percent upper confidence limit of that central tendency.10 For waters that have impairments that are associated with relevant POC

10 Confidence limits are indicative of the accuracy of the mean. In statistics, a confidence interval is a type of interval

estimate computed from the statistics of the observed data that might contain the true value of an unknown population parameter. If repeated samples were taken and the 95 percent confidence interval was computed for each sample, 95 percent of the intervals would contain the population mean. A 95 percent confidence interval has a 0.95 probability of containing the population mean. 95 percent of the population distribution is contained in the


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identified in Table 6.1-1, Enbridge did not calculate existing water quality, because the listed impairment establishes that they are not high quality waters. Enbridge used this approach because the 95 percent upper confidence limit is a method previously used by the MPCA to characterize high quality waters.

MPCA-approved monitoring data is not available for all waterbody crossings. For these waters, Enbridge has assumed that they are currently achieving the applicable standard.

Existing water quality and applicable water quality standards are provided in Attachment G for

receiving waters. Some of the applicable surface water quality standards vary depending upon

the location of the waterbody within the River Nutrient Regions (“RNR”). These RNRs correspond

loosely to the EPA aggregated Level III Nutrient ecoregions. Figure 6.3-1 presents the Project in

relation to each RNR.

6.3 IMPAIRED WATERS

Enbridge has evaluated all receiving waters and the first hydrologically connected downstream waterbody associated with the Project to identify those that have been listed as impaired by the MPCA.

6.3.1 Receiving Waters

Attachment C includes information on waterbody impairment status for all receiving waters, as listed on the Section 303(d) list prepared by the MPCA and approved by the EPA in 2018. Table 6.3.1-1 summarizes the receiving water impairments.

TABLE 6.3.1-1 Receiving Waters with 303(d) Impairments Crossed by the Line 3 Replacement Project

Waterbody Milepos

t Impairment(s)

Proposed Crossing Method

Red River of the North

801.8 Mercury in fish tissue; Mercury in water column; Arsenic; Turbidity

HDD

Tamarac River 828.6 Aquatic macroinvertebrate bioassessments; Fishes bioassessments

HDD

Middle River 835.9 Turbidity; DO; Aquatic macroinvertebrate bioassessments HDD

Snake River 843.2 Aquatic macroinvertebrate bioassessments; DO; E. coli; Fishes bioassessments

HDD

South Branch Snake River

847.2 Fishes bioassessments Dry Crossing

Red Lake River 864.3 Mercury in fish tissue HDD

Clearwater River 875.4 Turbidity; Mercury in fish tissue HDD

Lost River 904.0 E. coli Dry Crossing

Silver Creek

907.1

Fecal coliform; Aquatic macroinvertebrate bioassessments

Dry Crossing

907.4 Dry Crossing

907.7 Dry Crossing

Clearwater River 922.3 Mercury in fish tissue; DO HDD

Walker Brook 924.2 DO Modified Dry Crossing

Mississippi River 941.1 Mercury in fish tissue HDD

Straight River 974.2 DO HDD

confidence interval. Enbridge used the ProUCL system recommended by the MPCA to calculate the 95 percent upper confidence limit.


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TABLE 6.3.1-1 Receiving Waters with 303(d) Impairments Crossed by the Line 3 Replacement Project

Waterbody Milepos

t Impairment(s)

Proposed Crossing Method

Shell River 976.6 Fishes bioassessments Dry Crossing

Shell River 981.4 Fishes bioassessments Dry Crossing

Shell River 991.2 DO HDD

Crow Wing River 993.3 Mercury in fish tissue HDD

Moose River 1048.0 DO Push-Pull

Mississippi River 1069.6 Mercury in fish tissue, TSS HDD


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Figure 6.3-1 River Nutrient Regions Crossed by the Project


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6.3.2 Downstream Waters

Enbridge also evaluated downstream waters with impairments. For this evaluation Enbridge identified the first hydrologically connected waterbody located downstream of each Project waterbody crossing location and determined whether that waterbody is listed on the Section 303(d) list prepared by the MPCA and approved by the EPA in 2018. Downstream waters with impairments are shown on Table 6.3.2-1.

TABLE 6.3.2-1 303(d) Impaired Waterbodies with Parameters of Concern Downstream of

Waterbodies Crossed by the Line 3 Replacement Project

Downstream Waterbody Name

Reach Description Impairment(s) a Distance Downstream

from Crossing Location (miles)

Tamarac River Stephen Dam to Red R Chlorpyrifos 3.8

Red Lake River County Ditch 96 to Clearwater R Mercury in fish tissue; turbidity 5.5

Clearwater River T148 R35W S31, west line to Clearwater Lk

Mercury in fish tissue 15.8

St. Louis River East Savanna R to Artichoke R Mercury in fish tissue 0.6

Otter Creek Little Otter Cr to t48 r16w s7, east line

Aquatic macroinvertebrate bioassessments

1.0

Clear Creek T48 R16W S33, west line to MN/WI border

Aquatic macroinvertebrate bioassessments; Fishes bioassessments; Turbidity

1.5

a Includes EPA-approved 2018 303(d) list impairments.

7.0 ANALYSIS OF PRUDENT AND FEASIBLE MEASURES TO MINIMIZE DEGRADATION

As stated in Section 4.0, prudent and feasible prevention, treatment or loading offset alternatives do not exist that would avoid degradation of existing high water quality (Minnesota Rules 7050.0265, subp. 5A). Although the Project cannot avoid degradation, Enbridge has prepared the following analysis of measures that prudently and feasibly minimize degradation to existing high water quality (Minnesota Rules 7050.0265, subp. 5A). Measures have been developed to minimize degradation through prudent and feasible prevention or treatment in waterbodies (Section 7.1) and wetlands (Section 7.2).

7.1 PRUDENT AND FEASIBLE PREVENTION AND TREATMENT MEASURES AT WATERBODIES

There are four primary construction activities that contribute to a net increase in loading or other degradation of existing high water quality in waterbodies, including:

• Installation of the pipeline across a waterbody;

• Travel across a waterbody;

• Removal of beaver dams; and

• Appropriation from a waterbody.


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Discharges at waterbodies are described in the Individual NPDES/SDS Antidegradation Assessment.

Section 7.1.1 analyzes the design considerations and constraints, expected performance, and reliability associated with the available pipeline installation methods at receiving waterbodies, and Section 7.1.2 describes additional prevention measures (i.e., BMPs) that Enbridge will implement to further minimize degradation at receiving waterbodies.

7.1.1 Selection of Pipeline Installation Crossing Method

There are seven different methods for installing the pipeline across waterbodies, which include five open trench methods and two trenchless methods further described below:

• Open Trench:

o Open Cut (Non-Isolated) Method o Push-Pull Method o Dry (Isolated) Method: Dam and Pump o Dry (Isolated) Method: Flume o Modified Dry Crossing Method

• Trenchless:

o Bore Method (non-pressurized) o Horizontal Directional Drill (“HDD”) Method (pressurized)

Table 4.0-1 of the Summary of Construction Methods and Procedures (see Appendix A of Attachment H) describes the waterbody crossing methods and waterbody characteristics that are most suitable for these different construction methods. Attachment G includes a justification for the crossing method selected at each waterbody based on the design considerations and constraints for that specific crossing. Table 7.1.1-1 summarizes the number of waterbody crossings proposed for each construction method. Blasting may be required in the vicinity of Little Otter Creek (MP 1118.4). Enbridge’s Blasting Plan is provided in Attachment I.

Table 7.1.1-1 Proposed Waterbody Crossing Construction Method Summary

Waterbody Crossing Construction Method Number of Proposed Waterbody Crossings

Trench: Open Cut (Non-Isolated) Method (includes 6 push-pull) 8

Trench: Modified Dry Crossing 9

Trench: Dry (Isolated) Method 152

Trenchless: Bore Method 22

Trenchless: HDD Method 21

Total 212

7.1.1.1 Trench: Open Cut (Non-Isolated) Methods

The open cut method is described in Section 4.1 of Appendix A of Attachment H, and Section 2.5.1 and Figure 24 of the EPP (Attachment H). Open cut crossings are typically completed within 24 to 48 hours depending on the size of the watercourse, as described in Section 2.1 of the EPP


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(Attachment H). Open cut crossing methods typically involve trenching through the waterbody while it is dry or frozen to the bottom (no perceptible flow) and direct excavation of the trench through the banks and bed of the watercourse can proceed similar to upland construction techniques. Construction while the waterbody is dry or frozen prevents the potential for sediment release during in-channel work.

This construction technique is the most prudent and feasible construction method for waterbodies surrounded by extensive wetland complexes that preclude the use of the dry crossing or HDD methods. A dry crossing is not feasible, given that the crossing cannot be isolated from the surface water or high water table of the adjacent wetlands. Currently, there are only two waterbody crossings where Enbridge is proposing use the open cut (non-isolated) method.

The features that the MPCA has identified as waterbodies, but field delineations determined were wetlands based on conditions at the time of survey (noted as “desktop” in Table C-1 of Attachment

C), will proceed when the feature is dry or frozen and has no perceptible flow in accordance with the EPP. This can occur provided the EI verifies that water is unlikely to flow between initial disturbance and final stabilization of the feature. If unanticipated flow conditions develop during construction of a given waterbody, Enbridge’s EIs will be notified immediately to determine the extent of the flow and Enbridge will install additional erosion and sediment control BMPs as necessary. If flows are significant, and sedimentation is likely to occur, work will be stopped, and Enbridge will switch to a dry crossing technique.

There are a limited number of locations where, due to surrounding saturated wetlands, it is not feasible to isolate the waterbody flow and an open cut trench crossing is proposed (see Enbridge Crossing Justification provided in Attachment G). This includes six locations where the push-pull method will be implemented (see Section 7.2.1.2). Section 3.7.1 of the EPP and Section 3.0 of the Summary of Construction Methods and Procedures (Attachment H) provide more detailed information on this crossing method.

As described in Section 2.5.1 of the EPP (Appendix H), Enbridge will install in-stream BMPs (e.g., silt curtains, bladder dams, or water gates) downstream of all open cut crossing locations where there is water prior to initiation of the crossing to minimize downstream sedimentation. The type of in-stream BMP utilized will depend on waterbody conditions (flow velocity, water depth, and the width of the waterbody) and will be selected by in the field depending upon the site-specific conditions at the time of crossing. As stated in Section 7.2.2, there may be some situations (e.g., push-pull crossings) where surrounding saturated wetlands may limit the ability to install in-stream BMPs and the effort may actually extend the duration of activity and create additional disturbance.

7.1.1.2 Trench: Dry (Isolated) Methods

Dry crossing (isolated) methods are described Sections 4.2 of Appendix A of Attachment H, and in Sections 2.5.2 and 2.5.3 and Figures 25 and 26 of the EPP (Attachment H). Dry crossing methods are the most prudent and feasible construction methods for waterbodies with a well-defined channel that can be dammed to dewater the construction area and isolate the crossing from the flow of water. Dry (isolated) crossings use either the dam and pump or flume technique. Both methods involve damming the stream both upstream and downstream of the crossing location and digging a trench in the dry work area to install the pipe. Water is routed around the work area either by pumping water around the work area through hoses, or by water flowing through a flume pipe. The construction work area will be dewatered and discharged into well-vegetated area on an adjacent stream bank as described in Section 5.1 of the EPP (Attachment


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H). Dry crossings are typically completed within 24 to 48 hours depending on the size of the watercourse as described in Section 2.1 of the EPP (Attachment H).

Of the 152 dry crossings, 78 are considered agricultural or road ditches. All of the agricultural ditches occur north of the Clearbrook Terminal along Enbridge’s existing mainline corridor. In general, these features have very similar characteristics and are small channelized ephemeral or intermittent ditches that carry a high sediment load due to limited riparian buffers and adjacent agricultural land use activities. In addition to the above description, the dry crossing method is the most prudent and feasible for these features because stream banks are stable and consistently sloped to allow for efficient and effective installation.

7.1.1.3 Modified Dry Crossing Method

In situations where the stream banks are stable, but conditions are too saturated to effectively dewater from the construction workspace, Enbridge will conduct a modified dry crossing method using a dam and pump. The only difference from the standard dam and pump method and this modified technique is that Enbridge will not dewater the trench and will utilize buoyancy control methods (see Section 3.7.3 of Attachment H) as appropriate to sink the pipe to the bottom of the trench. Enbridge will install in-stream BMPs downstream of these crossing locations prior to initiating the crossing to mitigate the potential for elevated sedimentation. The type of in-stream BMP utilized will depend on waterbody conditions (flow velocity, water depth, and the width of the waterbody) and will be selected by in the field depending upon the site-specific conditions at the time of crossing.

The dry and modified dry crossing techniques can also be implemented in frozen conditions if there is perceptible flow. Winter construction procedures for dry crossing techniques are described in Sections 2.5.2 and 2.5.3 of the Winter Construction Plan (Attachment J).

Enbridge will consider switching to an open cut crossing technique at a waterbody previously identified as a dry or modified dry crossing if:

• the waterbody is dry or frozen at the time of crossing as described in Section 2.5.1 of the Winter Construction Plan; or

• when there are water management concerns based on field conditions at the time of the crossing, such as downstream obstructions that cause ponding, or a high water table.

In either case, Enbridge will seek agency concurrence on any changes to crossing methods prior to initiating an alternative crossing method.

7.1.1.4 Trenchless: Bore Method (Non-Pressurized)

The bore method (non-pressurized) is described in Section 3.5 of Appendix A and Section 4.0 of the EPP (Attachment H). The bore method is typically used to cross narrow transportation corridors, such as roads and railroads, or narrow and stable watercourses. Waterbodies adjacent to these features may also be crossed; however, the bore method is not generally used to specifically cross surface water features because it is not suitable for areas with high water tables or loose substrates. Pressurized water or drilling mud will never be used to hold the hole open, as it will be during an HDD (see Section 7.1.1.5); therefore, there is no risk for an inadvertent return of drilling mud at these locations.


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Currently Enbridge proposes to cross 22 waterbodies (unnamed ditches and one judicial ditch) with the conventional bore method.

7.1.1.5 Trenchless: Horizontal Directional Drill Method (Pressurized)

The HDD method is described in Section 3.6 of Appendix A of Attachment H, and in Sections 2.5.4 and 11.0 of the EPP. HDD is a trenchless crossing method that involves no direct excavation to the banks or beds of the wetland or watercourse being crossed. This method can be implemented during frozen or non-frozen conditions. There is no difference in technique in frozen vs. non-frozen conditions; however, execution may take longer during frozen conditions related to equipment maintenance in extreme temperatures, snow removal, etc.

Before Enbridge determines that an HDD crossing technique is prudent and feasible at a given location, geotechnical surveys are conducted at the proposed site to determine the subsurface conditions. Section 3.6.1 of Appendix A of Attachment H describes the factors that must be evaluated to determine the technical feasibility of an HDD. This information, along with the HDD design and layout and any other available data, is used to determine if the HDD can be successfully installed. The HDD process, technical feasibility considerations and related information, are described in detail in Enbridge’s HDD Design Report; including Hydrofracture Analysis Reports and Site-Specific Commentaries for each HDD crossing (see Attachment K). Based on these reports, the subsurface conditions at all the proposed HDD locations are amenable to successful installation of a drill.

Enbridge is proposing to conduct 19 HDDs, which will cross 21 waterbodies (see Table C-1 of Attachment C). It is not prudent and feasible to install the pipeline using the HDD method at every waterbody crossing for a variety of reasons, some of which are described on a site-specific basis in Attachment G. Other reasons include the availability of HDD rigs (only 200 exist in North America that are capable of installing 36-inch pipe), cost (proposed HDDs for the Project range from 1 to 4 million dollars) and schedule (the HDD method can take several weeks to months to complete).

Drilling Mud and Additives

Drilling mud (potentially with the addition of additives) serves many functions as described in Section 3.6.1 of Appendix A of Attachment H, Maintaining drilling fluid circulation to the extent possible is the key to reducing the risk of inadvertent drilling fluid returns (also referred to as an “inadvertent release”).

The composition of drilling mud is primarily sodium bentonite, an absorbent aluminum phyllosilicate clay consisting mostly of montmorillonite. Bentonite is a naturally occurring clay that is inorganic, non-toxic, and non-irritating. Sodium bentonite expands when wet, absorbing several times its dry mass in water. Its unique rheological properties mean that small amounts of bentonite suspended in water to form drilling mud will create a viscous, shear-thinning material. The increased viscosity facilities the movement of drill cuttings out of the hole. The shear-thinning means that the viscosity of the fluid decreases under shear strain facilitating lubrication of the drill bit and pumping. Bentonite’s behavior in water (swelling) has also made it useful as a sealant (annular seal or plug for water wells).

Drilling additives help control sand content and flow, water hardness, keep the bore hole open and stable, prevent groundwater inundation and allow the bentonite to yield properly, amongst


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other functions. Small amounts of drilling mud additives are added to the bentonite and water slurry. As described in Table L-1 of Attachment L, as much as 475 pounds of drilling mud additive could be incorporated to 1,000 gallons of water, or as little as 3 quarts. Enbridge will only use those drilling mud additives approved by the MPCA and that do not contain prohibited ingredients on the list provided by the MPCA (see Section 7.4.4 and Attachment L). In Attachment L, Enbridge has provided a list of proposed drilling mud additives, preferred dosage rates associated with each drilling mud additive, chemical composition (Table L-1), and associated Safety Data Sheets. Drilling mud will be collected and disposed to an Enbridge approved off-site location.

Probability of an Inadvertent Release

The geotechnical data gathered to determine the feasibility of an HDD described above is also used to model the capacity of the soil to withstand the pressures of the drill and avoid widening or creating a fracture (hydraulic fracturing) through which drilling mud fluid will migrate. The HDD process, technical feasibility considerations, functions and compositions of drilling fluids, hydraulic fracture evaluation process, HDD design criteria, installation stress analysis, and risk assessment are described in detail in Enbridge’s HDD Design Report; including Hydrofracture Analysis Reports and Site-Specific Commentaries for each HDD crossing (see Attachment K).

These reports indicate that the risk of an inadvertent release for each HDD (drill) is low over most of the drill length, with the exception of the Red River (see Site-Specific Commentary provided in Attachment K). Specifically, the risk of inadvertent release is low (calculated factor of safety above 1.0) over the portion of the drill that underlies the waterbody. In some instances, the calculated factors of safety drop below 1.0, indicating a higher risk of inadvertent returns, for a portion of the drill beyond the banks of the waterbody, as the drill nears the exit point. Inadvertent drilling fluid returns near the exit point of HDDs are common and anticipated as the bit approaches the surface. These returns often occur within the temporary workspace limits and can easily be contained. Generally, the exit location, where the risk is relatively higher is located 700 feet or more from the waterbody (see individual Hydrofracture Reports in Attachment K for details).

Enbridge will reduce the annular pressure during the HDD crossing of the Red River at the locations identified as having an elevated risk of an inadvertent release (approximately 1,035 feet and 1,540 from the entry point) throughout the drilling process (i.e., pilot hole, reaming, and pullback) in order to reduce the potential for an inadvertent release.

Table 7.1.1-2 provides a summary of the 19 proposed HDDs crossing waterbody features in Minnesota and estimates the risk of an inadvertent return at each crossing based on the Hydrofracture Analysis Reports and Site-Specific Commentaries available in Attachment K. There currently is no known organization that collects nationwide data on the number and location of inadvertent releases during the execution of an HDD. Enbridge consulted with J.D. Hair & Associates, Inc. (“J.D. Hair”), an engineering firm that specializes in HDD pipeline crossings and authors of the Hydrofracture Reports in Attachment K. J.D. Hair has been involved in over 1,000 HDD crossings (design, monitoring, and/or execution) across the United States and in every continent except Antarctica and has also authored several technical papers regarding the execution of HDDs.11

11 http://jdhair.com/reference-material.

http://jdhair.com/reference-material


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TABLE 7.1.1-2 Line 3 Replacement Project

Summary of Hydrofracture Analysis Reports for Proposed HDD Crossings

Waterbody Feature (MP)

Total Horizontal

Length of HDD Crossing (ft)

Total Length of Adjacent Wetlands

Crossed (ft) a

Estimated Duration of

HDD

Risk of Inadvertent

Return b Section with Elevated Riskc

Distance from Waterbody to

HDD Entry Point (ft)

Distance from Waterbody to

HDD Exit Point (ft)

Red River (MP 801.8) 2,110 1,840 18 days Moderate to

High

Approximately 1,035 feet from entry point (north bank of river) and 1,540 feet from entry point (200 feet south of south bank)

1193 917

Tamarac River (MP 828.5) 1,463 194 27 days Low Last 40 feet of crossing 375 1,088

Middle River (MP 835.9) 1,755 68 27 days Low Last 70 feet of crossing 563 811

Snake River (MP 843.2) 1,574 241 21 days Low Last 40 feet of crossing 947 627

Red Lake River (MP 864.3) 3,182 325 57 days Low Last 70 feet of crossing 485 2,697

Clearwater River (MP 875.4) 2,768 854 48 days Low Last 75 feet of crossing 397 2,381

Clearwater River (MP 922.3) 2,818 1,528 45 days Low Last 90 feet of crossing 788 1,817

Mississippi River (MP 941.0) 2,217 1,782 50 days Low Last 70 feet of crossing 1,149 1,068

Hay Creek (MP 963.7) 2,802 1,555 50 days Low Last 60 feet of crossing 1,883 919

Straight River (MP 974.2) 3,579 1,020 75 days Low Last 300 feet of crossing 2,009 1,571

Shell River (MP 983.7) 2,309 1,256 45 days Low Last 140 feet of crossing 1,085 1,224

Shell River – Oxbow (MP 985.3)

4,413 3,198 80 days Low Last 140 feet of crossing 2,074 2,339

Shell River (MP 991.2) 1,589 0 45 days Low Last 60 feet of crossing 719 870

Crow Wing River (MP 993.3) 1,816 314 45 days Low Last 40 feet of crossing 1025 791

Pine River (MP 1017.3)d 1,433 40 30 days Low Last 40 feet of crossing 725 708

Daggett Brook (MP 1037.4) 2,262 684 50 days Low Last 80 feet of crossing 1,222 1,040

Willow River (MP 1066.4)d 1,418 1,023 50 days Low Last 50 feet of crossing 957 461

Mississippi River (MP 1069.6) 2,190 546 50 days Low Last 80 feet of crossing 715 1,475

East Savanna River (MP 1085.9)d

1,447 1,366 40 days Low Last 70 feet of crossing 735 712

a Attachment C identifies wetlands by feature ID and community type crossed by proposed HDD. b Based on the Delft Method as described in Section 5 of the HDD Design Report (Attachment K). c Elevated risk of a hydrofracture occurs when the soils confining capacity (pounds per square inch) is less than the estimated annular pressure exerted by the drill. d Additional geotechnical evaluation is pending at these crossings.


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Based on the experience of J.D. Hair, there have been few occurrences of inadvertent releases occurring within the channel of a waterbody. Out of 1,000 crossings, J.D. Hair estimates that less than 5 percent of have resulted in inadvertent returns occurring within a waterbody during the installation of an HDD in accordance with industry standards. It is important to note, however, that without a standardized methodology for monitoring and documenting occurrences this number is an estimate only. Inadvertent releases are more common in other areas of the drill alignment, such as near the entry and exit points.

Engineering Controls to Minimize Inadvertent Releases

Other components of HDD design or execution that help to prevent inadvertent releases during installation and that will be considered at all drill sites, and implemented as beneficial, include (Bennett and Ariaratnam, 2017; Skonberg and Muindi, 2014; Watson, 1995):

• Backfill and seal geotechnical borings performed along drill paths with neat cement grout and bentonite slurry to prevent boreholes from becoming conduits for inadvertent returns;

• Maintain minimum distance from the exit/entry locations and the waterbody thalweg, as influenced by the site-specific geotechnical conditions, and that typically is implemented as the pipe profile extends 40 feet below the thalweg;

• Select exit/entry locations with similar elevations to maintain similar head pressure and minimize releases when the drill breaks the surface;

• Incorporate surface casings where needed as dictated by the soil conditions and inadvertent return risks;

• Recycle drilling mud to minimize the amount of waste mud generated and reduce containment efforts;

• Excavate a borehole at the exit point to contain drilling mud from the pilot bore and subsequent bore reams;

• If interference is detected in the magnetic drilling guidance system, implement surface monitoring systems to monitor drilling direction; and

• Maximize mud circulation by adjusting the drilling mud rheology (i.e., the properties of the drilling mud, which may require using additives).

HDD Alternative Waterbody Crossing Methods South of the Clearbrook Terminal

If the primary drill path is unsuccessful during an HDD crossing, Enbridge will consider an alternate drill path before abandoning use of the HDD method and evaluating an alternative waterbody crossing method. Should an alternative crossing method be required, Enbridge will seek agency concurrence on any changes prior to initiating an alternative crossing method.

Table 7.1.1-3 identifies the proposed alternative crossing method for each HDD crossing location south of the Clearbrook terminal. These are locations where the Project is co-located with a pipeline corridor, but the HDD method may not have been previously implemented to cross the


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waterbody, or the Project is co-located with an electric transmission line where linear below ground installation of a utility line has not occurred.

Table 7.1.1-3

Alternative Crossing Methods for Proposed Horizontal Directional Drill Locations South of the Clearbrook Terminal

Waterbody Name Alternative Crossing Method

Justification

Clearwater River (MP 922.3) Modified Dry

Crossing Due to the large wetland complex surrounding the waterbody a standard dry crossing would be difficult

Mississippi River (MP 941.0) Modified Dry


Hay Creek (MP 963.7) Open Cut -

Wet Very wide at crossing location

Straight River (MP 974.2) Modified Dry


Shell River (MP 983.7) Modified Dry


Shell River – Oxbow (MP 985.3) Modified Dry


Shell River (MP 991.2) Open Cut -

Wet Due to high flow/volume output

Crow Wing River (MP 993.3) Open Cut -


Pine River (MP 1017.4) Open Cut -


Daggett Brook (MP 1037.4) Open Cut -

Wet Due to the large wetland complex surrounding the waterbody a standard dry crossing would be difficult

Willow River (MP 1066.4) Open Cut -


Mississippi River (MP 1069.6) Open Cut -


East Savanna River (MP 1085.9) Modified Dry


Mississippi River (MP 1069.6) ORVW Alternative Crossing Method

As described in Section 5.3, the Mississippi River is a restricted-use ORVW. There are two crossings of the Mississippi River as shown in Table 7.1.1-3; however, the crossing at MP 1069.6 is co-located with a transmission line. The crossing at MP 941.0 is co-located with an existing pipeline corridor where a pipeline has been successfully installed using the HDD crossing method. Therefore, additional analysis is warranted of the crossing at MP 1069.6 to determine whether HDD is the least degrading prudent and feasible method that minimizes degradation of this ORVW. Enbridge has completed the geotechnical borings and a Hydrofracture Analysis of the Mississippi River HDD crossing location which is provided in Attachment K.

Due the width, depth, and stream velocity of the Mississippi River crossing, Enbridge identified the wet open cut crossing method alternative for this location. However, this method will only be implemented as a last resort should the proposed HDD be unsuccessful, and, consistent with the site-specific HDD Inadvertent Release Response Plans (“IRRPs”) (Attachment M). A wet open cut crossing method will require workspace modifications resulting in approximately 3.2 additional acres of impact. A comparative analysis of construction impacts is provided in Table 7.1.1-4.


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Table 7.1.1-4

Alternative Crossing Method Construction Impact Comparison for the Mississippi River Crossing at MP 1069.6

Description HDD Method (acres) Wet Open Cut Method (acres)

Total Workspace Required 5.29 8.48

Total Forested Impacts a 4.95 6.41

Wetland Impact by Type

- Fresh (Wet) Meadow 0.05 0.12

- Hardwood Swamps 0.36 0.22

- Coniferous Swamps 0.29 0.16

- Floodplain Forests 0.48 1.21

Total Wetland Impact 1.17 1.70 a Inclusive of forested upland and wetland.

Stream hydraulic data derived from a Rosgen survey conducted in 2018 suggest that if the wet open cut alternative was used, the installation of a temporary bridge will be not be feasible given the stream depth and velocity, even during baseflow conditions. Therefore, to complete the wet open cut of the Mississippi River, Enbridge will deploy dragline excavators on both sides of the river, excavating from the middle of the channel toward each bank until minimum trench depths have been realized. Enbridge will make all reasonable efforts to install BMPs immediately downstream of any in-stream excavations; however, with stream velocities anticipated between 5.3 and 11.3 ft/sec, BMPs options will be limited. Dragline excavation is expected to be a multi-day operation, followed by installation of a concrete-coated pipe section that is pulled into position and sunk into the trench. Streambed materials stockpiled in the additional temporary workspace will then be used to backfill the pipe section and streambanks. Enbridge anticipates the excavation, installation and backfill to take approximately one week.

7.1.1.6 Beaver Dam Removal

Enbridge reviewed locations where beaver dams are known to exist based field survey notes and comments on the Project provided by regulatory agencies (i.e., the MDNR). Enbridge also conducted field visits to the beaver dams to gather additional data to understand potential construction concerns, whether or not removal would require additional workspace not already in the Project design, and if removal of the dam would be beneficial to construction. Based on the identification of known beaver dams, Enbridge is proposing to remove two beaver dams in waterbodies (see Attachment C).

7.1.2 Best Management Practices

To access the right-of-way across waterbodies, Enbridge will install bridges, culverts, or ice bridges along the travel lane, and at access roads or improved haul routes that cross waterbodies. Section 2.1.1 of Appendix A of Attachment G describes the different bridge and culvert types that may be utilized and their suitability based on construction activity, site conditions, and engineering specifications. Attachment C identifies the proposed bridge or culvert type for waterbodies crossed by the travel lane, access roads or improved haul routes. Section 2.4.2 of the EPP (Attachment H) describes the BMPs that will be implemented to minimize sediment from entering the waterbody associated with bridges and culverts. Bridges will be removed during final cleanup or after restoration as described in Section 2.6.3 of the EPP. During frozen conditions, Enbridge may develop ice bridges to cross narrow waterbodies where conditions allow as described in the Winter Construction Plan (Attachment J).


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Enbridge will implement the following BMPs and mitigation measures to prevent, minimize, or treat TSS loading and associated effects downstream of crossings:

• Enbridge will monitor upcoming weather forecasts to determine if significant rainfall is anticipated during construction and will implement wet weather shutdown procedures as described in Sections 1.3 and 2.0 of the EPP.

• Minimize the duration of in-stream work and comply with MDNR fishery timing restrictions for the waterbodies noted in Table C-1 of Attachment C where dry crossings are proposed (Section 2.1 of the EPP).

• At trench crossings, Enbridge will neck down beginning 20 feet from the ordinary high-water mark (“OHWM”) on the working side of the construction workspace (Section 2.2 of the EPP).

• Comply with the conditions of the MPCA NPDES/SDS Construction Stormwater General Permit and the SWPPP, as outlined in Section 2.2 of the EPP.

• Follow the process for installation described in Section 2.5 of the EPP (Attachment H) and 2.5 of the Winter Construction Plan (Attachment J), which requires installation of sediment control measures prior to grading, segregation of streambed material, prohibits storage of streambed spoil within the stream, installation of trench plugs, and installation of stabilization measures.

• Pump sediment laden dewatering discharge into a vegetated area or dewatering structure and prevent sediment and other materials from entering the watercourse following the procedures described in Section 5.1 of the EPP.

• Once the pipeline is installed, the waterbody will be restored as described in Section 2.6 and 7.0 of the EPP.

• Conduct permanent seeding using BWSR riparian native seed mixes as described in Section 7.8 of the EPP (Attachment H). Specialized seed mixes may be utilized as needed; for example, the BWSR Eroding Bank Stabilization pilot seed mix to restore and stabilize steep eroding slopes (Section 7.9.2 of the EPP).

• Wastes will be handled, stored, and disposed of in accordance with Section 9.0 of the EPP.

• Enbridge will implement SPCC measures as described in Section 10.0 of the EPP, including restricting refueling activities to upland areas, and requiring sufficient spill response kits for each construction crew.

• Terrestrial invasive and noxious plant species and aquatic invasive species will be managed according to the INS Management Plan included as Appendix B of the EPP (Attachment H).

• Enbridge will conduct post-construction monitoring at waterbody features in accordance with the Post-Construction Wetland and Waterbody Monitoring Plan (Attachment N).


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In order to meet Enbridge’s requirements to inspect the pipeline during operations as discussed in Section 7.3, and also to provide access to the waterbody during installation of an HDD for monitoring and response in the case of an inadvertent release of drilling mud (see Section 7.4.6), Enbridge will only clear 30 feet of vegetation within the 50-foot permanent right-of-way along the drill path (see Figure 4.4-1 of Appendix A of Attachment H); note that Enbridge has committed to this reduced width to further minimize potential effects associated with vegetation removal on aquatic resources. This will not generally require removal of vegetation on the stream banks. Vegetation will be cleared, but roots will be maintained, which will aid in stabilizing the soils and reducing erosion potential. No grading or trenching will occur along the drill path, except at six locations where free-span engineered bridges will be installed (see Attachment C-1). Bridge headers will be set back 10 feet from the top of bank and some limited grading may be required to allow for the safe installation of the bridge. There are also three crossings (Red Lake, Clearwater (MP 875.4), and Middle rivers) where Enbridge’s landowner agreements require no tree clearing between the HDD entry/exit and the river.

Enbridge will appropriate from surface water features for construction activities such as fugitive dust control, HDD drilling mud, buoyancy control and hydrostatic testing. Enbridge has applied for water appropriation permits for these activities from the MDNR, which included evaluating potential sources based on the sensitivity of the resource and adequate waterbody flow rates and volumes to protect aquatic life and allow for downstream uses. Enbridge will comply with the conditions of those permits and will only use MDNR-approved sources. During appropriation activities, Enbridge will manage the intake hose to minimize sediment intake from the waterbody and to prevent disturbance of the waterbody bed as described in Section 6.1 of the EPP (Attachment H).

Beaver Dam Removal

The following BMPs will be implemented during removal of beaver dams:

• Enbridge will monitor weather conditions prior to removal;

• Activities will be conducted during frozen conditions when possible;

• Removal will be limited to the removal of the debris that comprises the dam structure;

• Waterbody bed and bank material will not be removed or disturbed during debris removal;

• Most removal will be conducted using hand tools;

• Any required equipment will work off of the waterbody bank; and

• Ponded water will be released slowly to minimize potential TSS discharge below the dam.

7.2 PRUDENT AND FEASIBLE PREVENTION AND TREATMENT MEASURES AT WETLANDS

There are four primary construction activities that contribute to a net increase in loading or other degradation of existing high water quality in wetlands, including:

• Installation of the pipeline across a wetland;

• Travel across a wetland;

• Removal of beaver dams; and

• Discharge to a wetland.

Enbridge is not proposing to appropriate water from wetlands.


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Section 7.2.1 analyzes the design considerations and constraints, expected performance, and reliability associated with the available pipeline installation methods at receiving wetlands, and Section 7.2.2 describes additional prevention measures (i.e., BMPs) that Enbridge will implement to further minimize degradation at receiving wetlands.

7.2.1 Selection of Pipeline Installation Crossing Method

There are four different methods to install the pipeline across wetlands: two open trench methods and two trenchless methods.

• Open Trench:

o Modified Upland Construction Method (Open Cut or Standard Wetland Construction Method)

o Push-Pull Method

• Trenchless:

o Bore Method (non-pressurized) o HDD Method (pressurized)

During the design and planning process, Enbridge identifies the preferred method of pipeline installation based on the engineering design standards (e.g., U.S. Department of Transportation), presence of sensitive resources, landowner/community considerations, environmental regulations, and constructability considerations, including the ability to safely and effectively construct through the area, as described in the Summary of Construction Methods and Procedures (see Appendix A of Attachment H). Table 3.2-1 of Appendix A in Attachment H describes the applicable wetland types (using the Eggers and Reed, 2014 classification) and site-specific characteristics that are most suitable for these different construction methods. Attachment D identifies Enbridge’s proposed crossing method for each wetland crossed by L3R, and Table 7.2.1-1 summarizes the number of wetland crossings proposed for each construction method.

Table 7.2.1-1 Proposed Wetland Crossing Construction Method Summary a

Wetland Crossing Construction Method Number of Proposed Wetland

Crossings by Method Centerline Crossing Length

(miles)

Trench: Modified Upland Construction Method (Open Cut)

697 56.3

Trench: Push-Pull Method 41 11.3

Trenchless: Bore Method 56 0.3

Trenchless: HDD 40 2.8

Total 818 70.7

a As described in Attachment D, each wetland feature ID may be crossed using more than one crossing method based on wetland characteristics (e.g., location, extent, saturation) or other features (e.g., roads). Therefore, the “number of proposed wetland crossings by method” and corresponding “centerline crossing length” includes a wetland as crossed by the Open Cut method if any portion of that feature will be crossed as such. For example, wetland feature ID CLC5096a1W is proposed to be crossed using both the open cut and HDD method; therefore, that feature ID is included in the Open Cut totals to provide the most conservative estimate.


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7.2.1.1 Trench: Modified Upland Construction Method

The modified upland construction method (also referred to as open cut or standard wetland construction method) is described in Section 3.3 of Appendix A of Attachment H, and Section 3.0 and Figures 30 to 34 of the Environmental Protection Plan (“EPP”) (Attachment H). This construction technique can be implemented in non-frozen and frozen conditions working off of construction mats or ice roads. Winter construction procedures are further described in the Winter Construction Plan in Attachment J. It is most the most prudent and feasible method in wetlands with unsaturated mineral soils if constructed during non-frozen conditions, or in saturated soils with less than 12 inches of inundation with moderate to high bearing strength soils. Relative to the other wetland construction techniques, this is the quickest installation method. There are advantages and disadvantages associated with this construction technique during frozen vs. non-frozen conditions. If constructed in non-frozen conditions in saturated soils, multiple mat layers may be required as described in Section 3.3 of Appendix A of Attachment H, which may be mitigated in frozen conditions if weather conditions allow the development of ice roads. However, topsoil segregation, backfilling and grading can be more complicated in frozen conditions as described in the Winter Construction Plan, requiring additional grading and monitoring efforts relative to what would be required in non-frozen conditions.

7.2.1.2 Trench: Push-Pull Method

The push-pull method is described in Section 3.4 of Appendix A of Attachment H, and Section 3.7 and Figure 36 of the EPP (Attachment H). The push-pull technique is the most prudent and feasible method to cross saturated wetland features with greater than 12 inches of inundation and relatively competent peat soils as described in Section 3.4 of Appendix A of Attachment H. This method can only be used in non-frozen conditions where there is sufficient inundation to push-pull or float the pipe. If these conditions do not exist at the time of the crossing, then the modified upland construction method will be used. There are 41 wetlands where the push-pull method is proposed to be used.

7.2.1.3 Trenchless: Bore Method (Non-Pressurized)

As described in Section 7.1.1.4, the bore method is not generally used to specifically cross wetland features. However, this construction method is prudent and feasible to cross for wetland features that are adjacent to the road or railroad feature being crossed by the bore method (see Attachment D).

This method can be implemented in frozen or non-frozen conditions; there are no differences in technique in frozen vs. non-frozen conditions. There are 56 wetlands that are entirely crossed by a conventional non-pressurized bore. There are 20 locations where a bore pit associated with a bore crossing of a feature is located within a delineated wetland (see Attachment D). Once the bore is completed and the pipeline is tied in, the bore pit will be backfilled, and the wetland will be restored as described in Attachment H.

7.2.1.4 Trenchless: Horizontal Directional Drill Method (Pressurized)

The HDD method is described in Section 7.1.1.5. Enbridge is proposing to cross 40 wetlands that are adjacent to roads or waterbodies using the HDD method (see Attachment D). There are five locations where the entry/exit workspace associated with an HDD crossing is located within a wetland (see Attachment D). Enbridge will mat the workspace between entry and exit locations


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within wetlands as necessary, for the staging of equipment and materials. Once the drill and tie-in are completed, entry and exit pits will be backfilled, construction mats will be removed, and workspace will be restored as described in Attachment H.

Probability of an Inadvertent Release

As Table 7.1.1-2 provides a summary of the 19 proposed HDDs in Minnesota including the total length of adjacent wetlands associated with each crossing and estimates the risk of an inadvertent return at each crossing based on the Hydrofracture Analysis Reports and Site-Specific Commentaries available in Attachment K. A summary of the hydrofracture analyses for each HDD crossing is also provided in Attachment K.


Based on the identification of known beaver dams described in Section 7.1.1.6, Enbridge is proposing to remove six beaver dams in wetlands (see Attachment D).

7.2.2 Best Management Practices

The EPP (Attachment H) and Winter Construction Plan (Attachment J) describe the BMPs that will be implemented during the installation of the pipeline through wetland features, regardless of pipeline installation method (except where noted), that would further minimize degradation. These BMPs include the following:

• Enbridge will monitor upcoming weather forecasts to determine if significant rainfall is anticipated during construction and will implement wet weather shutdown procedures as described in Section 1.3 of the EPP.

• Use of construction mats, low ground pressure equipment, and/or ice roads to access wetland features (Section 3.1 of the EPP and Section 3.5 of the Winter Construction Plan);

• Trench-Line-Only grading and topsoil segregation as described in Section 1.10.1, 3.2. and 3.4 of the EPP at trench crossings.

• Implementation of temporary erosion and sediment control BMPs in accordance with MPCA NPDES/SDS Construction Stormwater General Permit requirements and described in Section 3.4 of the EPP.

• Enbridge will backfill and conduct rough/final grading at trench crossings as described in Sections 3.8 and 3.9 of the EPP and the Winter Construction Plan.

• Enbridge will utilize Minnesota Board of Soil & Water Resources (“BWSR”) native plant seed mixes to revegete wetland features as described in Section 7.7 of the EPP.

• Wastes will be handled, stored, and disposed of in accordance with Section 9.0 of the EPP.

• Enbridge will implement Spill Prevention, Containment, and Control (“SPCC”) measures as described in Section 10.0 of the EPP, including restricting refueling activities to upland areas, and requiring sufficient spill response kits for each construction crew.


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• Terrestrial invasive and noxious plant species (including wetland species) will be managed according to the Invasive and Noxious Species (“INS”) Management Plan included as Appendix B of the EPP.

• Enbridge will conduct post-construction monitoring at wetland features in accordance with the Post-Construction Wetland and Waterbody Monitoring Plan (Attachment N).

To access the right-of-way across wetlands, Enbridge will install construction mats along the travel lane, and at portions of access roads or improved haul routes that cross wetlands. In areas where additional stability is required (e.g., intersection of an access road and the construction workspace), Enbridge may install rock on top of geotextile fabric. Section 3.1 of Appendix A of Attachment H describes the different construction mat types that may be utilized and their suitability based on construction activity and site conditions. Attachment D identifies wetlands crossed by proposed access roads or improved haul routes. During frozen conditions, Enbridge may develop ice roads to access wetlands where conditions allow as described in Section 3.1 of the Winter Construction Plan (Attachment J).

7.2.2.1 Construction Dewatering in Wetlands

During construction, the pipeline trench or facility excavations may accumulate groundwater or stormwater after a precipitation event. In order to install the pipeline or facility infrastructure, dewatering of the excavation may be necessary in order to visually inspect the substrate and ensure that the pipeline can be safely installed and the excavation backfilled. The actual volume and location of water to be appropriated will be determined by the following conditions:

• Seasonality, soil saturation and existing groundwater levels;

• Weather conditions (e.g., precipitation); and

• Construction techniques.

During dewatering, Enbridge will typically utilize portable pumps. The number and size of pumps used during a dewatering event is based on the volume of water to be removed from the trench, Enbridge may also need to use a well point system for dewatering at site-specific locations, such as road bores, utility crossings, and mainline valve excavations. A well point system is used when groundwater recharge volumes in the excavation are greater than traditional dewatering techniques can manage. The system will consist of a series of small diameter wells installed via hydro-jetting that are connected by a header pipe to a well point pump (Figure 42 of the EPP [Attachment H]).

Pipeline trench dewatering will generally occur over a period of 3 days or less, except where special construction techniques will occur such as tie-ins, road bores, HDDs, or mainline valve installations which may occur over a longer, but still short-term period. Construction activities along the pipeline trench are continuously moving; depending on site conditions, up to one mile of trench could be constructed per day.

Construction dewatering discharges are subject to the MPCA NPDES/SDS Construction Stormwater General Permit for discharges to upland areas.12 Enbridge will generally locate dewatering structures within the construction workspace whenever practicable; however, site-

12 Authorization to Discharge Stormwater Associated with Construction Activity under the NPDES/SDS Program.

MNR100001. https://www.pca.state.mn.us/sites/default/files/wq-strm2-80a.pdf.

https://www.pca.state.mn.us/sites/default/files/wq-strm2-80a.pdf


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specific conditions may require that Enbridge consider using lands adjacent to the construction workspace. Section 5.1 of the EPP describes the site-specific characteristics that will be assessed when planning the discharge event and location of dewatering structure(s), including soil type, topography, discharge rate, filtering mechanism, and erosion and sediment control BMPs. All dewatering discharges will be directed through a filtering device such as a geotextile filter bag in a well-vegetated upland area (Figure 43 of the EPP [Attachment H]), or, when uplands are not accessible either because of site conditions and/or distance, to a geotextile bag within a straw or hay bale dewatering structure (Figure 44 of the EPP [Attachment H]). Enbridge will select the geotextile bag and dewatering structure appropriately sized for the water volume and sediment type (e.g., large versus fine sediments such as clays or silts). Straw bales used in a dewatering structure will meet Minnesota Department of Transportation 3882 Type 3 Specifications.13

There are areas along the Project where there are no suitable upland areas adjacent to or within the construction workspace to install dewatering structures. For example, the topography of a suitable location must be such that the discharged water does not flow back into the construction workspace. Further, the location must be close enough to the construction workspace to allow equipment to remove the geotextile bag full of sediment, which may be too heavy for removal by hand. In these situations, Enbridge would prefer to install the dewatering structures in wetlands.

During the discharge, water will be pumped through a hose to a geotextile bag, which captures sediments as the water flows through the bag. As the water slowly filters out of the geotextile bag, the straw bale structure provides additional erosion and sediment control. Temporary inundation in the area surrounding the dewatering structure may occur as the water slowly infiltrates.

Enbridge will monitor activities throughout the duration of the dewatering activity. Enbridge will adjust the flow volumes to not overwhelm the dewatering structure, follow the manufacturer’s recommendations regarding the use of geotextile bags, and replace as needed to avoid discharge of sediment laden water. Visual checks will be performed to ensure adequate treatment has been obtained and nuisance conditions (see Minn. R. 7050.0210, subp. 2) will not result from the discharge. If Enbridge observes that the geotextile bag and straw bale dewatering structure fails to adequately treat the discharge, Enbridge will stop the discharge and implement alternative or supplemental filtration, such as curlex bloc dewatering structures, or sand filters. Alternative filtration devices, such as sand filters, will be readily available to use as needed to adequately treat discharges; the selection of the filtration device will depend upon the volume and site-specific conditions. Enbridge will take immediate corrective actions to ensure dewatering activities are in compliance with applicable permits and certifications. Enbridge will monitor, maintain, replace, and supplement BMPs as required in the Project construction documents and as required by all applicable permits and plans, including the MPCA NPDES/SDS General Permit.14

Generally, discharge activities require minimal to no ground disturbance as dewatering structures are placed on top of the ground surface. Once trench dewatering activities are complete in a given area, Enbridge will clean up the discharge area by removing bags and structures for disposal to an approved off-site location. Enbridge will restore any areas of incidental ground disturbance as described Section 7.0 and Appendix C of the EPP (Attachment H), respectively.

13 http://www.dot.state.mn.us/pre-letting/spec/2018/2018-spec-book-final.pdf. 14 Refer to Section 11.1 Inspections and Maintenance of the MPCA General Permit.

http://www.dot.state.mn.us/pre-letting/spec/2018/2018-spec-book-final.pdf


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7.2.2.2 In-Wetland Erosion and Sediment Control BMPs

As mentioned above, Section 3.4 of the EPP describes when and where erosion and sediment control measures will be installed relative to wetland features. Enbridge is currently developing a Stormwater Pollution Prevention Plan (“SWPPP”) associated with the NPDES/SDS Construction Stormwater General Permit for the Project. The SWPPP identifies the types of materials that may be installed according to:

• type of construction activity proposed;

• topographic conditions;

• hydrology and seasonality; and

• proximity to sensitive resources.

The erosion and sediment control BMPs may be installed based on these factors; however, the specific BMP will be selected in the field based on the site-specific conditions at the time of construction. Additionally, in some saturated wetland conditions, the ability to install erosion and sediment control BMPs may be limited and the effort to install such BMPs may both extend the duration of activity and create additional disturbance.

As described in Section 1.3 of the EPP (Attachment H), Enbridge will monitor upcoming weather forecasts to determine if significant rainfall is anticipated during construction activities. Enbridge will be responsible for appropriately planning work, considering the potential for wet conditions, and being prepared to implement mitigation measures in the event of wet weather conditions and/or excessive water flow. Enbridge will be responsible for implementing any and all such corrective measures deemed necessary should conditions subsequently worsen where the above described criteria cannot be met.

The Trench-Line-Only topsoil segregation method will typically be utilized in wetlands as described in Section 1.10 of the EPP and illustrated in Figures 30 through 34 of the EPP. Topsoil is not typically segregated in inundated wetlands. During clearing in wetlands, vegetation and trees within wetlands will be cut off at ground level, leaving existing root systems intact (see Section 3.2 of the EPP) and tree stumps will be grubbed from the trench only. These measures reduce the potential for erosion and sediment transport within the wetland.

Access to wetlands will be achieved by placing construction mats along the travel lane, except in some open water wetlands where Enbridge cannot achieve stability using construction mats. In these situations, Enbridge will utilize equipment mounted on tracked pontoons (i.e., swamphoe), and install the pipe using the push-pull method as described further in Section 3.4 and Table 3.2-1 of the Appendix A of the EPP (Attachment H). Figures 35 and 36 of the EPP illustrate the push-pull method.

Further, Enbridge will minimize the length of trench and amount of time that the trench is left open in wetlands to minimize water-management issues associated with high groundwater tables or precipitation events. Enbridge will take reasonable steps to ensure that the duration of open trench in wetlands, including tie-ins, is minimized to the fullest extent possible.15 Once the pipe is installed in the trench, the trench will be immediately backfilled and rough and final grading will proceed as described in Sections 3.8 and 3.9 of the EPP, including seedbed preparation and installation or repair of erosion and sediment control BMPs.

15 The push-pull technique will typically require additional time to install relative to a standard open cut crossing.


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Enbridge will monitor the erosion and sediment control BMPs installed in wetlands at least once every day during active construction and within 24 hours after a rainfall event greater than 1/2-inch in 24 hours to ensure integrity and effectiveness. Enbridge will repair, replace, or supplement all non-functional BMPs with functional BMPs, and will inspect drainage ditches and conveyance systems for evidence of erosion and sediment deposition. Enbridge will remove all deltas and sediment deposited in surface waters, including drainage ways, catch basins, and other drainage system and restabilize areas where sediment removal results in exposed soil. Enbridge will complete removal and stabilization within seven calendar days of discovery unless precluded by legal, regulatory, or physical access constraints.16

Enbridge will identify the potential locations of these erosion and sediment control BMPs in wetlands on the Project’s Environmental Plan Sheets included with Enbridge’s SWPPP.17 Because site-specific field conditions can vary at the time of construction activities, Enbridge has developed a Decision Tree (Figure 7.2.2-1) that will be utilized by Enbridge’s Environmental Compliance Management Team18 to evaluate the potential location, extent, and type of erosion and sediment control BMPs to be implemented based on the wetland saturation level. The location and extent of these BMPs identified in the Environmental Plan Sheets may be modified during construction using the Decision Tree based on site-specific conditions. Enbridge will document all changes to the Environmental Plan Sheets and maintain inspection and maintenance records at the site as required by the General Permit.19 The Enbridge Environmental Compliance Team, in consultation with the Independent Environmental Monitors,20 will determine the final location, type, and extent of BMPs in the field.

7.2.2.3 Calcareous Fens

The Project crosses one calcareous fen, the Gully 30 fen at MP 894. Site-specific construction plan including additional mitigation measures were developed as a part of the Gully 30 calcareous FMP currently in review by the MDNR.


The following BMPs will be implemented during removal of beaver dams:

• Enbridge will monitor weather conditions prior to removal;

• Activities will be conducted during frozen conditions when possible;

• Removal will be limited to the removal of the debris that comprises the dam structure;

• Wetland material will not be removed or disturbed during debris removal;

• Most removal will be conducted using hand tools;

• Any required equipment will work off of construction mats in wetlands; and

• Ponded water will be released slowly to minimize potential TSS discharge below the dam.

16 Refer to Section 11.1 “Inspections and Maintenance” of the General Permit. 17 Refer to Section 5.1 of the General Permit for SWPPP content requirements, including requirements for the

Environmental Plan Sheets. 18 Enbridge’s Environmental Compliance Management Team is described further in Section 2.0 of Enbridge’s

Environmental Monitor Control Plan. 19 Refer to Section 20.2 of the General Permit. 20 Roles and responsibilities of the Independent Environmental Monitors is described further in Section 3.0 of

Enbridge’s Environmental Monitor Control Plan.


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Figure 7.2.2-1 Erosion Prevention and Sediment Control Installation Guidelines Decision Tree: In-Wetland Scenarios


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7.3 RIPARIAN VEGETATION RESTORATION

Riparian vegetation is valuable for nutrient cycling, energy transfer, water quality, and aquatic and terrestrial biodiversity.21 Characteristics of riparian areas vary from site to site and may be dominated by herbaceous or woody vegetation. Root structures of plants help stabilize streambanks, while areas dominated with woody vegetation provide shade along streambanks. Riparian areas also serve as a buffer from other land uses, such as agricultural land and urban areas.

Enbridge has conducted an analysis of the waterbodies crossed by the centerline of the L3R (Attachment O) that provides the following information:

• Rosgen22 stream classification, along with a brief discussion of each stream’s ecological relationship to its watershed;

• Type of vegetation within the riparian zone of each stream; and

• The width and length of the corridor where vegetation will be temporarily cleared and/or permanently converted at each stream crossing.

The stabilization methods to be implemented at each waterbody crossing are described in Sections 1.17 and 2.6 of Enbridge’s EPP. Enbridge will use the BWSR riparian native seed mix at waterbody crossings unless an alternative seed mix is more appropriate (e.g., eroding bank stabilization seed mix) as described in Sections 7.8 and 7.9.2 of the EPP. Enbridge will also conduct post-construction monitoring at waterbodies in accordance with the Post-Construction Wetland and Waterbody Monitoring Plan (Attachment N).

Title 49 Code of Federal Regulations (“CFR”) 195.412 (a) states that “each operator shall, at intervals not exceeding 3 weeks, but at least 26 times each calendar year, inspect the surface conditions on or adjacent to each pipeline right-of-way. Methods of inspection include walking, driving, flying or other appropriate means of traversing the right-of-way.” Enbridge’s preferred method to perform these required inspections is flying. To perform these inspections aerially, the right-of-way needs to be adequately cleared to be able to identify abnormal surface conditions.

During operations, Enbridge will maintain a 50-foot permanent right-of-way centered over the pipeline. Enbridge will maintain the permanent right-of-way by removing woody shrubs and trimming branches overhanging the right-of-way approximately every 5 years to preserve pipeline integrity and to facilitate inspection of the pipeline; however, rather than maintain the 50-foot permanent right-of-way clear of vegetation in riparian areas at trench crossings, Enbridge will only remove woody vegetation along a 10-foot corridor, and trees within a 30-foot corridor centered over the pipeline to further minimize impacts associated with vegetation removal (see Figure 4.1-1 in Appendix A of the EPP [Attachment H]). As described in Section 7.1.2, Enbridge will maintain a 30-foot-wide corridor free of trees and woody vegetation in riparian areas at HDD crossings (see Figure 4.4-1 in Appendix A of Attachment H).

21 Natural Resources Conservation Service. 1996. Riparian Areas Environmental Uniqueness, Functions, Values.

RCA Issue Brief #11. Natural Resources Conservation Service. 22 Rosgen, D.L. 1994. A Classification of Natural Rivers. Catena Volume 22, pp 169-199.


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Other maintenance activities (e.g., maintenance digs) may occur as necessary over the life of the pipeline. Routine vegetation maintenance along the permanent right-of-way may include mowing, grubbing, and treatment/mitigation of undesirable species once identified, including herbicide treatment as approved by the appropriate agencies.

7.4 COMPARISON OF LEAST DEGRADING PRUDENT AND FEASIBLE MEASURES WITH EXISTING WATER QUALITY

This section describes the anticipated loading or other causes of degradation and compares the existing water quality to the anticipated water quality when the proposed activity is fully implemented at wetlands (Sections 7.4.1 and 7.4.2) and waterbodies (Sections 7.4.1 and 7.4.3). Enbridge has also evaluated the anticipated loading and compared the existing water quality to anticipated water quality if an inadvertent loss of drilling mud were to occur during an HDD in wetlands (Sections 7.4.4 and 7.4.5), and waterbodies (Sections 7.4.4 and 7.4.6). Section 7.4.7 provides a comparison of the existing and expected economic conditions and social services when the proposed activity is fully implemented (Minnesota Rules 7050.0280 Subp. 2C(1), (2), and (3)). The results of this analysis will demonstrate that the Project is the least degrading prudent and feasible alternative that prudently and feasibly minimizes degradation of surface waters (Minnesota Rules 7050.0265, subp. 5A).

7.4.1 Overview of Potential Effects of the Least Degrading Prudent and Feasible Alternative

Enbridge evaluated potential temporary water quality effects that could occur during construction for each POC (see Section 7.4.1.1), and potential effects to the beneficial uses (i.e., aquatic ecosystem effects) (see Section 7.4.1.2). Special consideration is given to the potential effects on wild rice (see Section 7.4.1.3). The anticipated water quality as a result of the right-of-way access, pipeline installation methods, removal of beaver dams, and appropriation and discharge activities is described in Section 7.4.2 and Section 7.4.3, respectively.

Enbridge anticipates that HDD installation will be accomplished as planned without inadvertent loss of drilling mud. However, water quality associated with inadvertent loss of drilling mud is described in Sections 7.4.4, 7.4.5, and 7.4.6.

Enbridge also anticipates that restoration activities at all surface water crossing locations will reduce the duration of water quality impacts associated with potential vegetative changes (see Sections 7.1.2, 7.2.2, and 7.3). Post-construction monitoring efforts at wetlands and waterbodies affected by construction will continue until the hydrology and vegetation performance standards described in the Post-Construction Wetland and Waterbody Monitoring Plan have been met (Attachment N). Note that a separate post-construction monitoring effort has been established for portion of the Project that crosses the Gully 30 calcareous fen as part of the FMP submitted to the MDNR.

7.4.1.1 Potential Water Quality Effects

This section describes the potential temporary effects of pipeline installation, right-of-way access (e.g., access roads and haul routes), and appropriation and discharge activities for each POC identified in Section 6.1. While the magnitude and duration of effects will vary between construction methods, the mechanisms by which construction could potentially increase loading are the same, as described below.


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TSS

The primary potential effect of pipeline installation across surface waters will be the potential temporary increase in TSS associated with the removal of riparian vegetation, disturbance of channel bed and banks and temporary resuspension of sediments. The placement of construction mats, ice roads, bridges, or culverts over surface waters may also contribute to the resuspension of sediments during the installation and removal process, and the introduction of sediments as equipment travels across these features. Water appropriation activities and beaver dam removal may also contribute to the resuspension of sediments in waterbodies. Construction dewatering discharges into wetlands may contribute a temporary increase in TSS. The magnitude of increased TSS will vary depending on the pipeline installation or access method, BMPs, and site-specific conditions, as described below. The duration of increased TSS concentrations is influenced by the settling properties of the particles and the hydraulics of the surface water. For pipeline installation using trenchless construction methods, there will be no construction within the surface water, and no increase in TSS is anticipated.

Mercury

There will be no addition of mercury to surface waters by any of the construction activities. Because inorganic and organic mercury are associated with sediment particles, the resuspension of sediment and the release of sediment porewater into the water column can result in temporary increase in total (dissolved + particulate) mercury concentrations.23 As with TSS, the magnitude of the total concentration increase is influenced by the degree of sediment resuspension and the mass of bound mercury in the resuspended sediment. Duration will be related to the settling properties of mercury-containing particles and the hydraulics of the water body.

The potential risk associated with the resuspension of mercury-containing sediment will be primarily related to the shift of mercury from the particulate into the dissolved state. The environmental chemistry of inorganic and organic mercury does not promote such a shift to the dissolved, mobile state. The resuspended sediment particles with adsorbed inorganic solid-phase mercury sulfide will not result in the release of dissolved mercury sulfide. The abiotic oxidation-dissolution kinetics of mercury sulfide are slow24 suggesting that particles will resettle prior to any significant dissolution. The hydrophobic nature of organic mercury means that the organic mercury will be found adsorbed to organic matter found in the sediment. Upon resuspension, desorption of hydrophobic chemicals into the dissolved state is slow compared to the resettling of organic matter,25,26 suggesting little or no change in dissolved organic mercury concentrations.

23 Grimsley K.J. and Swarzenski C. M. 2005. Assessment of total mercury and methylmercury concentrations at the

Barataria Preserve of Jean Lafeiite National Park and Preserve, Louisiana, during dredging operations, 2001-02. U.S. Geological Survey Scientific Investigations Report 2005-5093, 13 pp.

24 Holley E.A. et al. 2007. Mercury mobilization by oxidative dissolution of cinnabar (alpha-HgS) and metacinnabar (beta-HgS). Chemical Geology 240(2-3): 313-325.

25 Birdwell, J., Cook, R., & Thibodeaux, L. (2007). Desorption kinetics of hydrophobic organic chemicals from sediment to water: A review of data and models. Environmental Toxicology and Chemistry, 26(3), 424–434.

26 Jabusch T. et al. 2008. Effects of short-term water quality impacts due to dredging and disposal on sensitive fish species in San Francisco Bay. San Francisco Esturary Institute. Prepared for the U.S. Army Corps of Engineers, San Francisco District, 96 pp.


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Phosphorus

There will be no addition of phosphorus to streams by any of the construction activities.

The resuspension of sediments has the potential to release dissolved phosphorous found in the anaerobic porewater of the sediments.27 The impact on dissolved water column phosphorus concentrations will depend on the ratio of the released sediment porewater volume to the volume of water in the water column. Because the mass of porewater will be small, the magnitude of the phosphorus increase is also expected to be small. Any increase in phosphorus will be temporary and short-lived.

River Eutrophication

Eutrophication occurs when a waterbody becomes over-enriched with nutrients, causing excessive growth of plants and algae. Phosphorus is a nutrient, referred to by the MPCA as a “cause criterion” (MPCA, 2015). The Project may cause small, temporary, and short-lived increases in phosphorus (see discussion above); however, the phosphorus levels will not be expected to stimulate excessive plant growth. This expectation is based on the MPCA procedures for implementing river eutrophication standards (MPCA, 2015), which indicate that the duration for assessing potential river eutrophication is as a long-term summer average.

Minnesota’s river eutrophication standards also include parameters referred to as “response criteria:” DO flux, BOD5, and chlorophyll-a (MPCA, 2015). Concentrations of these parameters respond to elevated phosphorus levels. Given that the potential phosphorus concentration increase will be small, temporary, and short-lived, and not expected to stimulate plant growth, any potential phosphorus increase is not expected to affect concentrations of DO flux, BOD5, and chlorophyll-a.

Enbridge also separately assessed the potential for the Project to affect DO and BOD5 by mechanisms other than response to phosphorus (see discussion below).

Dissolved Oxygen

If construction results in increased TSS, the resuspension of sediments has the potential for temporary effects on water-column DO concentrations. When sediments are disturbed, the release of dissolved ferrous iron and sulfides from the porewater of anaerobic sediments will result in a reduction in the DO concentration. The magnitude of the DO decrease will be proportional to the amount of porewater released. Because the mass of porewater will be small the magnitude of the DO decrease is also expected to be small. The kinetics of the reaction are rapid, so the duration of the effect will be short, lasting on the order of minutes to hours.

Biochemical Oxygen Demand

If construction results in increased TSS, the resuspension of sediments has the potential to release dissolved organic compounds found in the sediment porewater and particulate organic matter into the water column. Depending on particle size, the particulate organic matter will

27 Wildman R.A. and Hering J.G. 2011. Potential for release of sediment phosphorus to Lake Powell (Utah and

Arizona) due to sediment resuspension during low water level. Lake and Reservoir Management 27(4): 365-375.


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resettle, while the dissolved organic compounds could remain in the water column. Dissolved organic materials have the potential to temporarily increase the BOD5 of the water column. However, while the potential for oxygen consumption is increased, the slow kinetics of BOD5 utilization will limit the impact on DO concentrations.28

7.4.1.2 Potential Aquatic Ecosystem Effects

Pipeline construction has the potential to affect stream ecosystems due to the removal of riparian vegetation and disturbance of channel bed and banks, with associated temporary increases in TSS and sediment deposition.29 Effects to both invertebrates and fish have been studied. Results indicate that sediment is the primary stressor, although changes in cover and channel morphology have the potential to impact fish habitat. Studies associated with EISs in Canada, where pipeline crossings are regulated under the Fisheries Act (Department of Justice Canada, 1985) have documented that the ability of aquatic ecosystems to recover from sediment disturbance is site-specific, and that when appropriate mitigation measures are used, the effects to aquatic ecosystems of crossing construction are short-term and local.30

The removal of riparian vegetation at forested or some scrub-shrub crossings will expose the stream to more solar radiation, potentially raising the local water temperature.31 This will result in short-term effects and is not expected to impact the stream ecosystem. Long-term impacts on stream temperature are dependent on other factors such as atmospheric conditions, the streambed, stream discharge, and topography.32 Small, shallow, and slow-flowing streams are expected to be the most susceptible to temperature increases from solar radiation. Coldwater fisheries (e.g., trout streams) will be most sensitive to these changes. The Project will only cross five coldwater fisheries, one of which (Straight River) will be crossed by the HDD method. It is expected that the effects associated with the removal of vegetation at these crossings will be localized, and the duration of impact will be dependent on the recovery of the woody riparian vegetation in the cleared area. However, of the five coldwater fishery crossings, Spring Brook and an Unnamed Stream (MP 1071.0) are the only two that have forested riparian vegetation adjacent to the crossing.

7.4.1.3 Potential Effects on Wild Rice

Generally, construction effects on waters that support natural wild rice stands will be localized and are anticipated to affect only those that are crossed by Project construction. This section describes the ways that pipeline construction might affect a water that supports natural wild rice

28 Jabusch T. et al. 2008. Effects of short-term water quality impacts due to dredging and disposal on sensitive fish

species in San Francisco Bay. San Francisco Estuary Institute. Prepared for the U.S. Army Corps of Engineers, San Francisco District, 96 pp.

29 Levesque L. and Dube M. 2007. Review of the effects of in-stream pipeline crossing construction on aquatic ecosystems and examination of Canadian methodologies for impact assessment. Environmental Monitoring and Assessment. 132:395-409.

30 Levesque L. and Dube M. 2007. Review of the effects of in-stream pipeline crossing construction on aquatic ecosystems and examination of Canadian methodologies for impact assessment. Environmental Monitoring and Assessment. 132:395-409.

31 Leinenbach, P., McFAdden G., and C. Torgersen. 2013. Effects of Riparian Management Strategies on Stream Temperature. U.S. Environmental Protection Agency, U.S. Geological Survey, Bureau of Land Management. 22pp.

32 Caissie, D. 2006. The thermal regime of rivers: A review. Freshwater Biology 51:1389–1406


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stands. The BMPs and construction techniques that Enbridge is proposing to prevent and minimize these potential effects are described in Sections 7.1 and 7.2.

Several aspects of the characteristics of wild rice are key to understanding the potential impacts that can result from pipeline construction. Wild rice is an annual emergent grass that re-establishes itself from seed each spring. Wild rice grows best in clear, shallow water (from 6 inches to 3 feet deep) with soft, organic bottom sediments, and a slow current. Wild rice is susceptible to water level fluctuations during the floating leaf stage during the early part of growing season, typically from May through June (1854 Treaty Authority, 2019).33

Construction could affect one year of wild rice harvest if it were to cause significant changes in water level or current velocity in a water that supports natural wild rice stands from the time wild rice enters the floating leaf stage (early June) until harvest is complete (end of August), or significantly increase turbidity in a water that supports natural wild rice stands during the wild rice growing season (May through September).

Construction could cause longer-term effects on a wild rice stand if it were to significantly alter the depth or composition of the sediment of the wild rice stand, or permanently change the water level or velocity at a wild rice stand.

The introduction of aquatic INS could present risks to waters that support natural wild rice stands during construction. Enbridge will implement the BMPs described in Appendix B of the EPP (Attachment H), including protocols for inspecting and decontaminating equipment during pipeline construction to manage the spread of aquatic INS.

The type of potential construction impacts to wild rice, and likelihood of their occurrence, varies depending on the construction method and the distance from the crossing. Construction methods associated with waters that support natural wild rice stands include trenchless crossings (i.e., HDD), trench crossings (i.e., open cut and dry crossings), and open cut crossings of wetlands (including push-pull). Enbridge also evaluated potential impacts to wild rice associated with water appropriations and right-of way access.

Trenchless Crossing (HDD)

HDD crossings prevent direct impacts on wild rice because they do not disturb stream bed sediment or alter the flow in the stream. Enbridge plans HDD crossings at 11 locations identified as waters that support natural wild rice stands (see Table 5.4-1). Waters downstream of HDD crossings that support natural wild rice stands are identified in Attachment E.

The primary risk associated with HDD crossings is an inadvertent release of drilling mud. An inadvertent release of drilling mud to a water that supports natural wild rice stands could present risks associated with increased turbidity, changes in the composition of wild rice stand sediment, or mechanical damage to wild rice plants during cleanup activities. To prevent any potential adverse effects associated with sulfate, Enbridge will not use any drilling mud additives that contain sulfate. Enbridge has assessed the probability of a release at each HDD (see Section 7.1.1.5) and established protocols and BMPs to prevent the release of drilling mud and to

33 MPUC Docket Nos. PL9/CN-14-916 and PPL-15-137, Jeffrey Lee (Barr Engineering) expert witness testimony

submitted January 31, 2017, Docket ID 20171-128682-05.


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minimize effects if a release occurs as described in Sections 7.4.4, 7.4.5, and 7.4.6. Site-specific HDD IRRPs are provided in Attachment M.

The effect of increased TSS/turbidity will depend on the time of year, the amount of drilling mud released, and the flow regime of the stream. High turbidity can prevent light from reaching plants under the water (Thompson and Luthin, 2004). A wild rice stand has the most potential to be affected by increased turbidity during the early growing season (from ice-out until mid-June), which is typically when wild rice grows long enough to reach the surface of the waterbody (1854 Treaty Authority, 2019). The magnitude of any effect during this period will depend on the duration of the turbidity increase at the stand. Generally, an inadvertent release and the subsequent cleanup will create a short-term turbidity pulse, with duration of a similar scale to a turbidity pulse associated with a high precipitation event. Such a turbidity pulse is not anticipated to damage the productivity of a wild rice stand.

The effects of potential sedimentation of drilling mud at a wild rice stand will depend on the amount of drilling mud released during a specific event and the flow regime of the stream at the time of the release. Generally, because of the fine particle size of drilling mud,34 a concentrated sedimentation event that results in a thick sediment blanket is not expected. Further, variation in stream bed sediment thickness and composition already occurs naturally in response to flood events. Wild rice accommodates such variations because it is an annual plant that reseeds each year.

If an inadvertent release were to occur at an HDD crossing, cleanup activities could damage the wild rice plants if the release took place during the growing season or damage the seed bed and rooting zone. Wild rice stands are located within a few hundred feet downstream of each of these crossings. However, as discussed above these impacts are anticipated to be temporary due to the annual nature of the plant.

Trench Crossings (Open Cut and Dry Crossings)

Enbridge plans a dry crossing of the Lost River where wild rice has been documented. Waters downstream of trench crossings that support natural wild rice stands are identified in Attachment E.

Enbridge will largely avoid the sensitive floating leaf stage of wild rice (typically May through June, depending on weather conditions) at the Lost River through compliance with the MDNR in-stream fishery restriction of March 15 through June 30. In addition, the section of the Lost River that will be crossed has previously been disturbed by alterations connected with USACE flood control efforts in the 1960s and installation of seven crude oil pipelines within Enbridge’s Mainline corridor, most recently by the Alberta Clipper Pipeline constructed in 2009-2010 using a dry crossing method. Despite this previous disturbance, wild rice is present there today in sufficient quantities that the waterbody could meet the criteria to be added to the MPCA wild rice waterbodies list. Current data shows that wild rice has re-established itself and flourished after those projects were completed.

After completion of the river crossings, Enbridge will restore each crossing location and wild rice vegetation will be expected to reestablish. The pipeline trench will be backfilled with the spoil material and parent streambed excavated from the trench unless otherwise specified in state or

34 <2.5 micrometers (“µm”) to 4 µm as described in Section 7.4.4.


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federal permits. The in-stream trench will be backfilled so that the stream bottom is similar to its pre-construction condition, with no impediments to normal water flow. No permanent impacts on wild rice vegetation at any of the crossings are anticipated.

Potential effects of a trench crossing on a downstream water that supports natural wild rice stands during the wild rice growing season will be associated with changes in flow or increased turbidity. Changes in flow are not anticipated, because the full flow of the stream is routed around the crossing and will contribute to flow at the downstream location. The potential for increased turbidity depends on the nature of the sediment at the crossing, the velocity of the current, and the distance between the crossings and the downstream water that supports natural wild rice stands. Dry crossing BMPs will also reduce the potential for sediment release, including the restoration of waterbody beds and banks before returning flow through the construction area (Section 2.5 of Attachment H). Some of these waterbodies crossed are designated fisheries and Enbridge will avoid in-stream work as required by the MDNR (see Table C-1 of Attachment C for timing restrictions), thereby largely avoiding the submerged growth phase that is dependent on clear water for light penetration.

Studies of the effects of dry crossings on brook trout streams indicated that these methods were highly effective at limiting sediment release and the associated risks to fish and fish habitat due to turbidity and sedimentation (Reid, 2002). Given that the risks to wild rice stands are also associated with turbidity and sedimentation, Enbridge anticipates that dry and modified crossings will not affect wild rice during the growing season or cause longer-term effects on wild rice stands.

Wetland Crossings

Any sediment disturbed by construction of a wetland crossing will remain in the vicinity of the crossing. Sediment transport is mitigated by wetland vegetation and lack of channelized flow (Richardson, 1989 as cited in Jordan et al. 2003), and therefore no effects would be expected beyond the extent of the wetland. Therefore, no effects to waters that support natural wild rice stands are anticipated due to wetland crossings.

Water Appropriations

Water appropriations will occur at 12 waters identified as waters that support natural wild rice stands (see Table 5.4-1). Enbridge will manage the intake hose to minimize sediment intake from the waterbody bed and adequate waterbody flow rates and volumes will be maintained to protect aquatic life and allow for other beneficial uses (see Section 6.0 of Attachment H).

Enbridge also evaluated potential effects of water level changes due to appropriation withdrawals on waters that support natural wild rice stands. Appropriation from waters that support natural wild rice stands is expected to cause minimal, temporary water level decreases that are not expected to cause adverse impacts to wild rice during the floating leaf stage, or any stage of its annual life cycle.

Right-of-Way Access

One existing access road along the Soo Line North ATV Trail north of the Project near MP 1055.7 crosses a water that supports natural wild rice stands, the Moose River, as shown on Table 5.4-1. Enbridge will utilize the existing bridge over the Moose River where the access road crosses. The BMPs and construction techniques that Enbridge is proposing to prevent and minimize any


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potential effects to wild rice in receiving or downstream waters are described in Sections 7.2.1 and 7.2.2.

7.4.2 Anticipated Wetland Water Quality during Construction

Construction will result in some unavoidable physical alteration of wetlands in the form of permanent fill, permanent and temporary wetland type conversion, and temporal loss as described in Section 9.2.1 of the Section 404 Project Application. The magnitude and extent of potential wetland water quality effects will vary depending on the right-of-way access method or pipeline installation method, as described below. The proposed pipeline installation method for each wetland crossed by the Project is provided in Attachment D.

As described in Section 7.2.2.1, during construction the pipeline trench or facility excavations may accumulate groundwater or stormwater after a precipitation event. In order to install the pipeline or facility infrastructure, dewatering of the excavation may be necessary in order to visually inspect the substrate and ensure that the infrastructure can be safely installed and excavation backfilled. There are locations along the Project where uplands adjacent to the construction workspace are limited, and discharges may occur in wetlands. The effects to water quality effects associated with this construction dewatering in wetlands are discussed below.

Enbridge will provide compensatory wetland mitigation for unavoidable Project permanent fill and for wetland type conversion of scrub-shrub and forested wetlands within the permanently maintained 50-foot-wide easement, as well as temporal loss and temporary conversion, in accordance with the USACE and EPA Final Rule regarding Compensatory Mitigation for Losses of Aquatic Resources 33 CFR Parts 325 and 322 and 40 CFR Part 230 (2008), the St. Paul District USACE Mitigation Policy, and internal St. Paul District guidance. Enbridge has prepared a Wetland Compensatory Mitigation Plan (“Mitigation Plan”) (Attachment P) in coordination with the USACE, MPCA, and MDNR. The Mitigation Plan includes a proposal to mitigate wetland impacts by the purchase of approved wetland bank credits, based on guidance provided by the agencies regarding mitigation ratios and wetland categories.

Right-of-Way Access

Enbridge will use the construction workspace and only approved roads to access wetland areas. Construction mats or rocks on top of geotextile fabric will be placed along the travel lane in delineated wetlands within the construction workspace and along access roads (see Section 2.1 of Appendix A in Attachment H). Use of these crossing methods will minimize potential loading of standing water that would otherwise result from disturbance of the wetland surface during equipment crossings. In winter conditions, frost/ice roads may be constructed to access the construction workspace (see Section 2.1 of Attachment J), which drives frost into the ground and provides a compacted layer of snow and ice for construction traffic.

The types of construction mats that will be used include: timber mats, made of hardwood materials bolted together; and laminated mats, made of laminated wood materials. The construction mat materials are not expected to reduce the water quality POC discussed in Section 6.1. If standing water is present during installation and removal of construction mats or rock over geotextile fabric, temporary increase in TSS load and associated potential water quality effects described in Section 7.4.1.1 may result. However, because water is not flowing at these locations, and due to wetlands’ natural capacity to act as a filter to remove sediments (Richardson, 1989 as


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cited in Jordan et al. 2003), the extent of the temporary water quality effects will be limited to the area around the construction mats, and long term effects to water quality are not anticipated.

Trench: Modified Upland Construction Method

If water is present during non-frozen conditions, the modified upland construction method may result in temporary elevated levels of TSS and associated potential water quality effects described in Section 7.4.1.1. However, because water is not flowing at these locations, and due to wetlands’ natural capacity to act as a filter to remove sediments (Richardson, 1989 as cited in Jordan et al. 2003), the extent of the temporary water quality effects will be limited to the vicinity of the excavation, and long term effects to water quality are not anticipated.

Trench: Push-Pull Method

Push-pull construction is anticipated to result in temporary elevated levels of TSS and associated potential water quality effects described in Section 7.4.1.1. Effects are expected to be similar to those associated with the modified upland construction method where water is present; however, because wetland water is slightly deeper at these locations, the water quality effects may extend slightly further from the trench location. Due to wetlands natural capacity to act as a filter to remove sediments (Richardson, 1989 as cited in Jordan et al. 2003), long term effects to water quality are not anticipated.

Trenchless: Bore Method

At bore crossings where the bore pits are in upland locations, bore construction will not involve wetland work. These crossings are not anticipated to result in an increase in loading for any POC. Further, as discussed in Sections 7.1.1.4, the proposed conventional bores will not use pressurized water or drilling mud to hold the hole open, which eliminates risk for an inadvertent return at these locations. Therefore, no water quality effects are anticipated.

At bore crossings where the bore pit is within a wetland and water is present during non-frozen conditions, excavation of the bore pit is anticipated to result in temporary elevated levels of TSS and associated potential water quality effects described in Section 7.4.1.1. The extent of the temporary water quality effects will be limited to the vicinity of the bore pit excavation. Due to wetlands natural capacity to act as a filter to remove sediments (Richardson, 1989 as cited in Jordan et al. 2003), long term effects to water quality are not anticipated.

Trenchless: HDD Method

Because HDD crossings will not involve wetland work, they are not anticipated to result in an increase in loading for any POC. The potential for water quality effects due to unanticipated release of drilling mud are discussed in Sections 7.4.4 and 7.4.5.

Construction Dewatering in Wetland Areas

Construction through certain areas, particularly large wetland complexes that encompass the construction workspace, may require dewatering the excavated trench into a wetland area. Although filtering devices will be used to reduce loading in the discharged water as described in Section 7.2.2.1, this activity may result in temporary elevated levels of TSS and associated potential water quality effects described in Section 7.4.1.1.


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Beaver Dam Removal

Although beaver dam removals will be conducted during frozen time periods when possible, and ponded water behind the dam will be released slowly, it is expected there will be a temporary increase in TSS load, as well as associated potential water quality effects described in Section 7.4.1.1.

7.4.3 Anticipated Waterbody Water Quality during Construction

Pipeline installation and right-of-way access (e.g., bridges, culverts) activities at waterbodies may result in temporary impacts on water quality. The magnitude and extent of potential water quality effects will vary depending on the pipeline installation method or bridge/culvert type, as described below. The proposed pipeline installation method and bridge/culvert type for each waterbody crossed by the Project is provided in Attachment C. In addition, water appropriation activities at waterbodies may affect water quality as described below. Waterbodies proposed for appropriation are identified in Table C-1 of Attachment C.

Trench: Open Cut (Non-Isolated) Crossings

Enbridge anticipates that during an open cut crossing, the disturbed stream bed will temporarily increase the load of TSS in the water downstream if there is perceptible flow at the time of construction. Elevated levels of TSS could also be accompanied by the other potential water quality effects described in Section 7.4.1.1. The magnitude of temporary TSS loading will depend on waterbody size, flow level, the specific in-stream activity (i.e., trenching vs. pipe laying), and the particle size distribution of the disturbed bed material. In general, based on the BMPs and mitigation measures Enbridge will use to prevent and minimize TSS loading downstream of open cut crossings (as described in Section 7.1.2), the increase in TSS loading and associated potential water quality effects will be minor and temporary and limited to the duration of in-stream construction. After completion of in-stream work, restoration, and recruitment from aquatic biota from upstream sources, these resources will return to pre-construction conditions within a few years and Enbridge anticipates there will be no long-term effects on streambed composition or fishery resources.

Dry (Isolated) Trench Crossings

Enbridge anticipates that dry crossing methods, including the modified dry crossing method, will temporarily increase the load of TSS in the water during construction and removal of the dam, and by the flow over the disturbed stream bed when flow is restored. When using the modified dry crossing method, Enbridge will install in-stream BMPs to limit the increase in TSS load during removal of the dam (see Section 7.1.1.3). Elevated levels of TSS could also be accompanied by the other potential water quality effects described in Section 7.4.1.1.

Dry crossings typically result in lower TSS and associated impacts when compared to open cut crossings. Enbridge collected TSS data during dry crossings conducted in the summer of 2017 along the 13-mile segment of the Project in Wisconsin referred to as “Segment 18.” The TSS data was collected prior to the crossing, during the crossing activity, and after the crossing was completed at three locations. Temporary TSS increases of approximately 2 to 50 milligrams per liter (“mg/L”) were recorded during the crossing activity as shown in Table 7.4.3-1. After the crossing was completed, upstream and downstream TSS levels showed only minor differences,


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supporting the conclusion that downstream TSS concentrations return to background levels within a matter of hours.

Table 7.4.3-1 Line 3 Replacement Project

TSS Concentrations Measured at Dry Crossings on Segment 18

Waterbody Flow

Regime

OHWM Width (feet)

Date of Installation

Date of Post-Construction

Sampling Location

Pre-Construction TSS (mg/L)

Pipe Installation TSS (mg/L)

Post-Construction TSS (mg/L)

Unnamed Stream

P 6 7/27/17 8/1/17 Upstream Not available 9.6 22.0

Downstream 13.4 60.0 20.8

Pokegama River

P 30 8/8/17 8/15/17 Upstream 13.4 12.3 9.8


Little Pokegama River

P 10 9/11/17 9/19/17 Upstream 20.7 4.6 3.8


Note: Ordinary High-Water Mark (“OHWM”)

Assessments of magnitude of increased sedimentation has also been completed. Reid et al. (2002) conducted a study on the effectiveness of two dry crossing methods (dam and pump and flume method) in limiting the amount of sediment released during in-stream pipeline construction and associated effects on downstream fish and fish habitat in six brook trout streams. This study included crossings of brook trout streams in Minnesota, Nova Scotia, and Ontario in the summers of 1998 and 1999, and indicated that compared to wet open cut crossings of similar-sized watercourses, increases in temporary mean downstream TSS loading during dry crossing construction is at least seven times lower. Further, the study indicated that dry crossings can be very effective at: (1) minimizing increases to downstream suspended sediment concentrations during in-stream construction; and (2) preventing sediment-induced effects on habitat and fish abundance downstream of pipeline water crossings.

This study showed that once the in-stream activity associated with the dry crossing was complete, downstream TSS concentrations returned to background levels with one to ten hours (Reid et al., 2002).

Trenchless Bore Crossings (Non-Pressurized)

Because bore crossings involve no in-stream work, they are not anticipated to result in an increase in any POC. Further, as discussed in Sections 7.1.1.4 and 7.2.1.3, the proposed conventional bores will not use pressurized water or drilling mud to hold the hole open, eliminating the risk for an inadvertent return at these locations. Therefore, no water quality effects are anticipated.

Trenchless HDD Crossings (Pressurized)

Because HDD crossings involve no in-stream work, they are not anticipated to result in an increase in loading for any POC. The potential for water quality effects due to unanticipated release of drilling mud are discussed in Sections 7.4.4 and 7.4.6.


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Right-of-Way Access

Enbridge will cross waterbodies using existing bridges associated with public roads and haul routes to the extent feasible. In cases where a suitable bridge crossing is not available, Enbridge will use clear span or non-clear span bridges as required for safe crossings of the waterbody. In some instances, culverts or flumes covered with a ramp or rock will be installed to allow water flow at waterbody crossings or road approaches over ditches. Table 2.1-1 of Appendix A of Attachment H summarizes the advantages and disadvantages of these three crossing methods. Sediment release is possible for all of these bridge crossing methods during installation and removal of any appurtenances installed on the banks or in the bed of the waterbodies. In frozen conditions, construction of frost/ice roads may be needed to access the right-of-way (see Table 1.4-1 in Attachment J). Development will begin as soon as weather conditions allow. These bridges can be strengthened by removing snow and flooding if needed to create a safe surface for equipment access.

Each of these bridge types are designed to prevent soil from entering the waterbody. Debris or vegetation that becomes lodged on the bridge support will be removed and disposed of in an upland area. Soil that accumulates on the bridge decking will be removed daily, or as deemed necessary by the Environmental Inspector.

Water Appropriations

Where water appropriation will occur, Enbridge will manage the intake hose to minimize sediment intake from the waterbody bed. Adequate waterbody flow rates and volumes will be maintained to protect aquatic life and allow for other downstream uses (see Section 6.0 of Attachment G).

Beaver Dam Removal

Although beaver dam removals will be conducted during frozen conditions when possible, and ponded water behind the dam will be released slowly, it is expected that levels of TSS will be temporarily elevated, as well as associated potential water quality effects described in Section 7.4.1.1.

7.4.4 Overview of Water Quality Effects Associated with an Inadvertent Release

No water quality impacts are anticipated for HDD crossings; however, should an inadvertent release of drilling mud occur, there will be temporary water quality impacts, referred to in this Section 401 WQC Assessment as unanticipated temporary water quality effects.

Enbridge has instituted numerous procedures to prevent, minimize, and treat unanticipated temporary water quality effects due to an inadvertent release of drilling mud. These procedures include:

• Evaluating the feasibility of implementing the HDD method at each location and the potential for inadvertent release (Sections 7.1.3 and 7.2.3 and Hydrofracture Reports provided in Attachment K);

• Implementing engineering controls to further minimize the probability of an inadvertent release (Section 7.1.1.5);


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• Assessing the benefits of drilling mud additives to reduce the possibility of a release, and the chemical composition and properties of each requested additive (Section 7.1.1.5, 7.4.4.1, and Attachment L);

• Evaluating the potential behavior of inadvertently released drilling mud (with and without additives), and ability to predict where releases may surface (Section 7.4.4.2);

• Implementing procedures to monitor for an inadvertent release in wetlands and waterbodies and establishing steps to be taken if conditions present the risk of a potential release (Section 7.4.4.3); and

• Pre-positioning site-specific materials and equipment that could be used for containment and recovery processes (Sections 7.4.4.4, 7.4.4.5, 7.4.4.6, and Attachment M).

The magnitude and extent of unanticipated temporary water quality effects will be a function of site-specific circumstances. The general types of water quality effects that could occur in wetlands and waterbodies are described in Sections 7.4.5 and 7.4.6, respectively.

For all wetlands and waterbodies proposed to be crossed using the HDD method, Enbridge has prepared site-specific IRRPs detailing specific actions and pre-positioned resources to avoid and mitigate any potential effects from unanticipated releases of drilling mud (see Attachment M).

7.4.4.1 Drilling Mud and Additives

The potential water quality effects of inadvertently released drilling mud are related to both its physical and chemical properties. The grain size of commercially available bentonite products ranges from <2.5 micrometers (“µm”) to 4 µm.35 Because of this small size, bentonite is colloidal in water, meaning that particles are so small that the action of water molecules is enough to keep them in suspension, especially in moving water channels.

Regarding the chemical properties of drilling mud, Reid and Anderson (1998) reviewed the toxicity of drilling mud and additives as it relates to freshwater organisms. They evaluated the common constituents of drilling mud separately and as a whole. Constituents evaluated included bentonite, xanthan gum, polymers, polyanionic cellulose, sodium polyacrylate, detergents (blend of anionic surfactants), and hydroeanated distillates. They establish that based on the EPA evaluation scale, most drilling mud constituents, individually, are considered practically non-toxic to slightly toxic to freshwater organisms. However, this study also notes that the interactions between drilling mud components can result in lower overall mud toxicity than expected from individual bioassays due to the sorption of components by bentonite. Bentonite has one of the highest cation exchange capacities known and through sorption, the bentonite acts as a detoxifier. Rather than dissolving in water, drilling mud additives tend to be adsorbed to and remain with the bentonite particles.

35 https://pubs.acs.org/doi/abs/10.1021/ac010116t

https://www.ncbi.nlm.nih.gov/pubmed/11569829

https://www.researchgate.net/publication/254353260_Effect_of_Particle_Size_of_Bentonite_on_Rheological_Behavior_of_the_Drilling_Mud/figures?lo=1

https://www.researchgate.net/publication/260030468_Microstructure_and_anisotropic_swelling_behaviour_of_compacted_bentonitesand_mixture/figures?lo=1

https://www.researchgate.net/publication/251662448_The_role_of_bentonite_particle_size_distribution_on_kinetic_of_cation_exchange_capacity

https://www.netwasgroup.us/fluids-2/commercial-bentonite.html

https://pubs.acs.org/doi/abs/10.1021/ac010116t

https://www.ncbi.nlm.nih.gov/pubmed/11569829







https://www.netwasgroup.us/fluids-2/commercial-bentonite.html


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Because drilling mud is primarily composed of bentonite (see additive dosage rates in Table L-1 of Attachment L), and most additives are non-toxic to slightly toxic, Reid and Anderson (1998) find that the overall toxicity of the drilling mud could be assumed to closely reflect that of bentonite.

The MPCA has prohibited several compounds from being used in drilling fluids. Enbridge will not use drilling fluids that contain any of the following compounds:

• Sulfate

• Nonylphenol ethoxylates:

o CAS no. 9016-45-9 Poly (oxy-1,2-ethanediyl, alpha-(nonylphenyl)-omega-hydroxy-

o CAS no. 26027-38-3 Poly (oxy-1,2-ethanediyl, alpha-(4-nonylphenyl)-omega-hydroxy-

o CAS no. 37205-87-1 Poly (oxy-1,2-ethanediyl, alpha-(isononylphenyl)-omega-hydroxy-

o CAS no. 68412-54-4 Poly (oxy-1,2-ethanediyl, alpha-(nonylphenyl)-omega-hydroxy-, branched

o CAS no. 127087-87-0 Poly (oxy-1,2-ethanediyl, alpha-(4-nonylphenyl)-omega-hydroxy-, branched

• Nonylphenol:

o CAS no. 25154-52-3 Phenol, nonyl- (assumes linear alkyl, not viewed as descriptive of commercial NP)

o CAS no. 104-40-5 Phenol, 4-nonyl- (assumes linear alkyl, not viewed as descriptive of commercial NP)

o CAS no. 84852-15-3 Phenol, 4-nonyl-, branched

7.4.4.2 Behavior of an Inadvertent Release

The behavior of an inadvertent release is a function of the amount of mud released, the flow conditions in the waterbody, and the timing and efficacy of the containment and recovery efforts.

The potential volume of mud released is a function of the size and length of the bore hole (which determines the volume of drilling mud required), the operating pressure, and the size of the fissure. In addition to the pumped volume there is the potential for additional drain volume post shut-off, related to the time required to recognize and confirm an inadvertent return to the surface is occurring and shut down pumps. The total amount of bentonite released will depend on the percentage of bentonite in the drilling fluid (which is typically adjusted throughout the drilling process). Additionally, the size of the mud particles, and their tendency to flocculate, will affect the rate at which they ultimately settle from the water column should the release occur in water. Releases of drilling fluids (mud and additives) and cuttings could occur at any point along the planned crossing including on land or in water. To properly understand the fate of drilling fluids


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released during an inadvertent return event, the location, volume, and composition of the release must be known.

The size of the surface water and conditions at the time of the release are all important factors in the potential downstream transport of muds in the environment as well as the potential impacts. A release occurring under high river flow conditions will lead to greater dilution and dispersion of drilling mud for several different reasons:

• Enhanced turbulence in the surface water during high flow conditions is likely to keep a release suspended in the water column for a longer period of time, when compared to low flow conditions.

• Stronger water flow and higher velocities will result in advection of drilling mud particles further from the release site, leading to greater dispersion and dilution of the mud.

• High flow conditions are the result of more water, which further dilutes the release, and results in deeper water, meaning sediments entrained within the water column will have to sink greater distances before depositing on the river bottom.

In addition, enhanced turbulence under high water flow conditions can lead to scouring, and other erosive processes that naturally load a watercourse with large amounts of sediment. As a result, the mud release may not result in a significant sediment load above background levels. It is unlikely that there will be large amounts of material settling out during high water flow conditions and the majority of the material is likely to be transported downstream with the natural sediment load.

In contrast, under low water flow conditions or wetlands with little to no flow, there will be less water for dilution/dispersion to take place and less distance over which sediments will have to settle (i.e., shallow water). Low turbulence levels will also result in a greater potential for sediments to deposit from the water column, when compared to higher flow conditions. Depending on background conditions of each particular surface water, released mud has a greater potential to increase sediment content within the water column above background levels. Should a release occur during winter with ice cover, there is also a greater potential for sedimentation due to lower turbulence and water flow during these conditions.

7.4.4.3 Monitoring

Early detection is key to minimizing the area of potential impact from an inadvertent release. Enbridge will monitor the drill path by observing land surfaces and surface waters for surface migration during pilot hole drilling, reaming, and pipe installation procedures. Enbridge will also walk the drill path to monitor for surface seepage, sinkholes, and settlement. In addition, flowing waterbodies will be monitored both upstream and downstream of the drill path. If an observer notices inadvertent release conditions, and lowered pressure readings on the drilling equipment, or sustained loss of drilling mud returns to the bore pit, shutdown will occur immediately. The on-site observation process during construction is further described in Section 11.1 of the EPP (Attachment H).


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7.4.4.4 Containment and Recovery

As discussed above, there will be the potential for additional drilling mud to be released after the drill is stopped related to the time required to recognize and confirm an inadvertent return to the surface is occurring and shut down pumps. The purpose of the initial containment response will be to limit the volume of the release and minimize potential turbidity and sedimentation impacts downstream. Following initial response measures, crew members will commence containment measures based on the approved site-specific IRRP (Attachment M). Drilling fluid recovery is ultimately dependent on the ability to isolate movement of the release location through implementation of containment measures. The effectiveness of those measures and feasibility of recovery varies based on conditions and location of a release.

The initial response to a wetland release will generally follow the process described in Section 11.3.2 of the EPP (Attachment H). Inadvertent releases in wetlands are generally contained by straw bales, sand bags, and silt fencing. Low ground pressure equipment (e.g., UTV, argo, morooka) will conduct limited passes to assist personnel carrying containment materials to a release location. Temporary access will be supported by construction matting within the wetland area as needed, and the on-site vacuum truck will be deployed if required by the volume of release. A vacuum truck typically has the ability to operate at a maximum distance of 150 feet from the truck. If a release were to occur outside of the proposed workspace, Enbridge will mobilize lightweight containment materials (e.g., straw bales, silt fence, sand bags) on foot to the release location to isolate the drilling fluid immediately. Once drilling fluid has been contained, Enbridge will determine if equipment access is necessary to aid in the response, and initiate agency consultations for developing alternate access, as necessary.

Should a release occur in a waterway, the containment methods utilized will depend on the size of release, water depth, flow velocity, and location of the release. In aquatic environments bentonite may harden, effectively sealing the inadvertent release location. In this event, response activities will be limited or unnecessary. However, if mud were to enter the water column, the typical response tactic will be to erect an isolation containment environment using the tools identified in Table 11.3-1 of the EPP (see Attachment H), or their equivalent, to facilitate a spill response team’s ability to contain and collect excess drilling mud. Containment is not always feasible for in-stream releases, especially in waterways with significant currents.

IRRPs that provide site-specific information regarding features crossed by each HDD and containment and recovery response tailored to site-specific conditions are provided in Attachment M.

Enbridge will complete a pre-construction visit at the site at least 2 weeks prior to initiating HDD setup and operations to determine if additional materials and equipment will be needed.

7.4.4.5 Recovery

Drilling fluid recovery methodology is not as variable as containment measures. When such measures effectively isolate the release from the stream flow, pumps or other appropriate measures are used to recover drilling fluid. When the release location cannot be isolated after initial in-stream containment installation, drilling fluid that has settled from the water column may deposit in the acute upstream angle of the containment tool when installed downstream of the release from the nearest bank, and recovery efforts will be localized to that location.


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7.4.5 Water Quality Effects in Wetlands Associated with an Inadvertent Release

An inadvertent release of drilling mud in a wetland could result in the following impacts:

• Drilling mud can act as an aquitard limiting groundwater flow in and out of wetland;

• Degradation of soil conditions resulting in reduced wetland plant recruitment and/or survivability; and

• Direct mortality of plants due to smothering.

The magnitude of these impacts will depend on the volume and location of the release, and the ability to promptly contain and recover the release (Reid and Anderson (1998). It should also be noted that the containment and recovery efforts themselves can result in degradation to the wetland environment. Wetland plant communities can be sensitive to disturbance, and a large release that requires construction matting, vehicles, and other equipment to access the wetland can result in additional damage. Access may also require clearing of vegetation. Enbridge will, in consultation with the agencies, consider the potential benefits of the cleanup versus the potential impacts when determining how to recover a release.

7.4.6 Water Quality Effects in Waterbodies Associated with an Inadvertent Release

An inadvertent release in a waterbody will result in downstream dispersion of diluted drilling mud. The extent of downstream impacts will be a function of the volume of drilling mud released, the flow characteristics of the waterbody, and the timing and efficacy of containment and recovery activities, as described in Sections 7.4.4.4 and 7.4.4.5. Unanticipated water quality effects in waterbodies will be associated with:

• Elevated TSS, which may result in adverse effects to aquatic invertebrates, fish and their habitat; and

• Bentonite and associated drilling mud additive effects, which together have been documented as having an effect similar to bentonite without additives, given the sorption capabilities of bentonite (Reid and Anderson, 1998).

Ultimately, the magnitude of the effects to the aquatic environment will be determined by the level of exposure (concentration and time), sensitivity of the organisms (lifestage, timing of release), and ability of the waterbody to remove or incorporate the sedimentation (Reid and Anderson, 1998).

7.4.7 Expected Economic Conditions and Social Services Resulting From the Project

Attachment A provides an overview of the MPUC certificate of need and route permit proceedings, the EIS, and Findings and Conclusions from the September 5, 2018 MPUC Order Granting a certificate of need for the Project. This document highlights the findings and conclusions, which describes the important economic or social changes resulting from the Project.


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8.0 ANTIDEGRADATION ASSESSMENT SUMMARY

Based on the analysis of prudent and feasible alternatives that avoid net increases (Section 4.0), assessment of existing uses and water quality (Sections 5.0 and 6.0), the analysis of prudent and feasible prevention and treatment alternatives (Sections 7.1, 7.2, and 7.3), and evaluation of the least degrading prudent and feasible alternatives (Section 7.4), Enbridge has summarized how the Project will:

• Protect existing uses (Minnesota Rules 7050.0265, Subp. 2) (Section 8.1);

• Provide compensatory mitigation as a means to preserve existing use in accordance with the conditions described in Minnesota Rules 7050.0265, Subp. 3) (Section 8.1.2);

• Protect beneficial uses (Minnesota Rules 7050.0265, Subp. 4) (Section 8.2);

• Protect surface waters of high quality (Minnesota Rules 7050.0265, Subp. 5) (Section 8.3); and

• Protect restricted ORVWs (Minnesota Rules 7050.0265, Subp. 6) (Section 8.4).

The Project does not cross any prohibited ORVWs (Minnesota Rules 7050.0265, Subp. 7).

8.1 PROTECTING EXISTING USES

Minnesota Rules, part 7050.0255, subpart 15, defines “existing uses” as “those uses actually attained in the surface water on or after November 28, 1975.” EPA guidance clarifies that a use is “actually attained” when (a) the water quality necessary to support a particular use has been attained; and (b) the use has actually occurred in the waterbody.36 Existing uses identify uses that have actually occurred in or on the waterbody, regardless of whether they are designated, as well as the corresponding water quality that has allowed the uses to occur.

8.1.1 Water Quality Effects

Water quality effects on surface waters are discussed in Sections 7.4.1, 7.4.2 (wetlands), and 7.4.3 (waterbodies). The POC evaluated in this Section 401 WQC Assessment: TSS, phosphorus, river eutrophication, DO, and BOD5, are associated with Class 2 uses, which are aquatic life and recreation. Mercury is associated with both Class 1 (domestic consumption), and Class 2 uses (see Table 6.1-2). Receiving waters that currently attain the applicable standards associated with Class 1 and 2 uses are noted in Attachment G. As described in Section 7.4.1.1, the existing uses will be maintained and protected at these waters because the increased loading of TSS and associated effects on mercury, phosphorus, and DO will be temporary, limited to the duration of in-stream construction, and therefore are not anticipated to result in long-term effects to streambed composition or benthic invertebrate and fish communities.

Wild rice has been identified as an undesignated existing use as described in Section 5.0. As evaluated in Section 7.4.1.3, the effects on waters that support natural wild rice stands will be localized and are anticipated to affect only those that are crossed by the Project.

36 See 80 Fed. Reg. 51019, 51027 (8-21-2015) (preamble to EPA’s final rule revising 40 CFR part 131).


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Waters that support natural wild rice stands are also present downstream of crossings as presented in Attachment E. Given that wild rice is an annual plant and the distance to downstream waters that support natural wild rice stands, potential impacts related to elevated TSS levels downstream of a crossing location are anticipated to be minor and temporary (see Section 7.4.1.3). Where fishery restrictions are in place, downstream effects will generally avoid the sensitive floating leaf stage. Suspended sediments resulting from the crossing will eventually settle to the stream bed or be removed from the system, allowing re-establishment of wild rice.

8.1.2 Compensatory Mitigation for Physical Alteration of Wetlands

Enbridge will restore all affected wetlands to pre-construction conditions, which is considered in-place compensation, but not in-kind and not in-advance. In applying the in-kind and in-advance factors, Enbridge has purchased mitigation credits from USACE-approved wetland mitigation banks to compensate for unavoidable wetland impacts in watersheds crossed by the Project.

Enbridge has prepared a Wetland Compensatory Mitigation Plan (Attachment P) in coordination with the USACE, MPCA, and MDNR. The Wetland Compensatory Mitigation Plan includes a proposal to mitigate wetland impacts by the purchase of approved wetland bank credits, based on guidance provided by the agencies regarding mitigation ratios and wetland categories.

8.2 PROTECTING BENEFICIAL USES

Minnesota Rules, 7050.0265, Subp. 4, prohibits the MPCA commissioner from approving activities that will “permanently preclude attainment of water quality standards.” All discharges associated with the Project are temporary and limited to the crossing location; therefore, the Project, including the activities regulated by the Section 401 WQC will not permanently preclude attainment of water quality standards in the receiving and downstream waters, thereby protecting beneficial uses.

As stated in Section 5.1, the MPCA adopted changes to its water quality standards, which the EPA approved in June 2018, that establish a TALU framework for watercourses (Minnesota Rule Chapters 7050 and 7052). The TALU framework is a significant revision and will enhance the protection and maintenance of state water resources. Currently none of the Project’s receiving waters have proposed use designations under the new framework.

8.3 PROTECTING SURFACE WATERS OF HIGH QUALITY

Minnesota Rules, 7050.0255, Subp. 21, defines a waterbody as “high quality” if it “exceeds, on a parameter-by parameter basis, levels necessary to support the protection and propagation of aquatic life and recreation in and on the water.” All receiving wetlands listed in Attachment D are assumed to meet applicable water quality standards and, therefore, to be high quality. Attachments C and G lists the applicable standards and the existing water quality for receiving waterbodies. Receiving waters that have existing water quality better than applicable standards are considered to be high quality.

The term “degradation” is defined as a “measurable change to existing water quality made or induced by human activity resulting in diminished chemical, physical, biological, or radiological qualities of surface water” (Minnesota Rules, 7050.0255, Subp. 11). In turn, “measurable change” is defined as “the practical ability to detect a variation in water quality, taking into account limitations in analytical technique and sampling variability” (Minnesota Rules, 7050.0255, Subp.


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24). The Project is anticipated to result in temporary degradation of the high quality receiving waters identified in Attachment C, and the receiving wetlands identified in Attachment B.

Antidegradation procedures require an analysis of alternatives that avoid net increases in loading or other causes of degradation through prudent and feasible prevention, treatment, or loading offsets (Minnesota Rules, part 7050.0280 Subp. 2A) (see Section 4.0). When there are no prudent and feasible alternatives to avoid net increases in loading, an analysis of prudent and feasible alternatives to minimize degradation is required (Minnesota Rules, part 7050.0280 Subp. 2C), as well as identification of the least degrading prudent and feasible alternatives see Section 7.0).

Enbridge has analyzed alternatives to avoid and minimize degradation of high quality waters. As a result of this process, Enbridge determined that although there are no prudent and feasible alternatives to completely avoid degradation of all high quality waters (see Section 4.0), there are prudent and feasible measures available to minimize degradation, including selection of crossing methods as described in Sections 7.1.1 (wetlands) and 7.2.1 (waterbodies), BMPs implemented during the construction activities described in Sections 7.1.2 (wetlands) and 7.2.2 (waterbodies), and the, implementation of HDD IRRPs described in Section 7.4.4 to prevent and minimize an unanticipated inadvertent release. Enbridge will also implement BMPs required in order to obtain coverage under the NPDES/SDS general construction stormwater permit (MNR100001). By implementing these prevention and treatment alternatives, Enbridge will minimize degradation of high quality waters.

8.4 PROTECTING RESTRICTED OUTSTANDING RESOURCE VALUE WATERS

There are no prohibited ORVWs downstream of the Project.

The Project will use HDD methods to cross a reach (Swan River to Sandy River) of the Mississippi River, which is a restricted ORVW. Minnesota Rules, 7050.0265 Subp. 6, states that discharge to a restricted ORVW must be controlled as necessary to preserve the existing water quality as necessary to maintain and protect the exceptional characteristics for which the restricted ORVW was designated. The SONAR accompanying the rule that designated this reach of the Mississippi River a restricted ORVW states that the river was so designated because it “…possesses outstanding and unique natural, scientific, historical recreational and cultural values…” (SONAR at 18). The SONAR also references the purpose and goals of the Wild and Scenic Rivers Act, which focuses on maintaining free-flowing conditions. However, the SONAR does not specify the water quality associated with the river’s exceptional characteristics.

The reach of the Mississippi River that will be crossed using the HDD technique is listed as impaired for TSS and mercury in fish tissue (Table 6.3.1-1). By using the HDD crossing method, for which no increase in TSS or mercury loading is anticipated, Enbridge will avoid TSS and mercury loading to the restricted ORVW. Further, Enbridge has developed an ORVW-specific HDD IRRP for this crossing detailing specific actions and pre-positioned resources to avoid and mitigate any potential effects from an unanticipated release of drilling mud (Attachment O). These measures will protect the exceptional characteristics for which this reach of the Mississippi River was designated a restricted ORVW.

The Project will also cross the Gully 30 calcareous fen, which has been designated a restricted ORVW. The portion of L3R in Minnesota that crosses the Gully 30 calcareous fen (Fen ID No. 35382) requires MDNR approval of an FMP under Minnesota Statutes, 103G.223. Enbridge


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prepared an FMP for the crossing of the Gully 30 fen, which has been submitted to MDNR for review and approval. The crossing of Gully 30 fen is co-located with existing Enbridge pipelines (Lines 65 and 67, respectively). The measures specified in the FMP for the crossing of the Gully 30 fen will protect the exceptional characteristics for which this calcareous fen was designated a restricted ORVW.


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9.0 REFERENCES

1854 Treaty Authority. 2019. Biology of Wild Rice. Available online at: http://www.1854treatyauthority.org/wild-rice/biology-of-wild-rice.html

Bennet, D. and S. Ariarantam. 2017. Horizontal Direction Drilling Good Practices Guidelines. 4th Edition. North American Society for Trenchless Technology (“NASTT”).

Canadian Energy Pipeline Association, Canadian Association of Petroleum Producers, and Canadian Gas Association. 2018. Pipeline Associated Watercourse Crossings Fish and Fish Habitat Impact Assessment Tool, 5th Edition. Prepared by Stantec Consulting Ltd.

Eggers, S.D. and D.M. Reed. 2014. Wetland Plants and Plant Communities of Minnesota and Wisconsin. U.S. Army Corps of Engineers. 68pp.

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