Appendix G Geotechnical Investigation

Plan of Development

FINAL

January 27, 2016

PACIFICORP

Energy Gateway South Geotechnical Investigation Plan of Development

PROJECT NUMBER: 124186

PROJECT CONTACT: PAT HASENOEHRL EMAIL: PHASENOEHRL@POWERENG.COM PHONE: 208-288-6230

POWER ENGINEERS, INC. GEOTECHNICAL INVESTIGATION PLAN OF DEVELOPMENT

Geotechnical Investigation Plan of Development

PREPARED FOR: PACIFICORP

PREPARED BY: PAT HASENOEHRL 208-288-6230

PHASENOEHRL@POWERENG.COM

POWER ENGINEERS, INC. GEOTECHNICAL INVESTIGATION PLAN OF DEVELOPMENT

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE i

TABLE OF CONTENTS

1.0 INTRODUCTION .................................................................................................................... 1

1.1 GEOTECHNICAL PLAN OF DEVELOPMENT PURPOSE AND STRATEGY .................................... 1

2.0 PURPOSE OF THE GEOTECHNICAL INVESTIGATIONS ............................................ 2

2.1 PURPOSE AND NEED ............................................................................................................... 2

3.0 GEOTECHNICAL EXPLORATION DESCRIPTION, STANDARDS AND REQUIREMENTS ............................................................................................................................... 2

3.1 GEOTECHNICAL EXPLORATION PLAN .................................................................................... 2 3.1.1 General Requirements .................................................................................................... 2 3.1.2 Temporary Ground Disturbance ..................................................................................... 3 3.1.3 Drilling Equipment Staging ............................................................................................ 9

3.2 DESCRIPTION AND IDENTIFICATION OF GEOTECHNICAL EXPLORATION SITES, ACCESS ROUTES, AND TEMPORARY DISTURBANCE ........................................................................................ 9

3.2.1 Overview of Borehole Site Locations and Selection Criteria ......................................... 9 3.2.2 Access Routes and Roads ............................................................................................. 10

3.3 IDENTIFICATION OF POTENTIAL GEOLOGIC HAZARDS ......................................................... 11 3.3.1 Overview of Geologic Hazards ........................................................................................... 11 3.3.2 Geologic Hazard Locations ................................................................................................. 17 3.3.3 Conclusions ......................................................................................................................... 19

3.4 GEOTECHNICAL EXPLORATION METHODS ........................................................................... 20 3.4.1 Geotechnical Drilling Methods .................................................................................... 20 3.4.2 Sampling Methods ........................................................................................................ 22 3.4.3 Geophysical Surveys .................................................................................................... 22

3.5 DRILL VEHICLE TYPES ......................................................................................................... 23 3.5.1 Truck Mounted ............................................................................................................. 23 3.5.2 All-Terrain Vehicles ..................................................................................................... 23 3.5.3 Tracked Vehicles .......................................................................................................... 23 3.5.4 Platform Rig and Helicopter ......................................................................................... 24

4.0 GEOTECHNICAL EXPLORATION LOCATIONS ......................................................... 28

4.1 INTRODUCTION ..................................................................................................................... 28 4.2 DRILLING LOCATIONS, ACCESS, AND SENSITIVE RESOURCES FOR ROUTE LINKS, SUBSTATIONS AND SERIES COMPENSATION STATIONS .................................................................... 28

4.2.1 Wyoming ...................................................................................................................... 28 4.2.2 Colorado ....................................................................................................................... 28 4.2.3 Utah .............................................................................................................................. 29 4.2.4 Substations and Series Compensation Sites ................................................................. 30

5.0 CONSTRUCTION PERMITS AND CLEARANCE SURVEYS ....................................... 31

5.1 ANTICIPATED DRILLING RELATED PERMITS ........................................................................ 31 5.2 ENVIRONMENTAL CLEARANCE SURVEYS AND SEASONAL RESTRICTIONS .......................... 31

6.0 GEOTECHNICAL INVESTIGATION SPECIFIC ENVIRONMENTAL PROTECTION MEASURES ............................................................................................................ 32

6.1 INTRODUCTION ..................................................................................................................... 32 6.2 DESIGN FEATURES OF THE PROJECT FOR ENVIRONMENTAL PROTECTION .......................... 32

POWER ENGINEERS, INC. GEOTECHNICAL INVESTIGATION PLAN OF DEVELOPMENT

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE ii

6.3 SELECTIVE MITIGATION MEASURES .................................................................................... 37 6.4 ADDITIONAL ENVIRONMENTAL PROTECTION MEASURES ................................................... 39

General ......................................................................................................................................... 39 Erosion Control and Soil Resource Protection ............................................................................. 39 Spill Prevention, Containment, and Countermeasures/Waste (Hazardous and Solid) ................. 40 Dust Control and Air Quality ....................................................................................................... 41 Noxious Weed Control ................................................................................................................. 41 Water Resources Protection ......................................................................................................... 41 Health, Safety and Fire Protection ................................................................................................ 41

FIGURES FIGURE 3-1 GEOTECHNICAL BORING WORK AREA ........................................................................... 4 FIGURE 3-2 PHOTO #1 PRE-AND POST DRILLING ............................................................................... 5 FIGURE 3-3 PHOTO #2: PRE- AND POST-DRILLING ........................................................................... 5 FIGURE 3-4 PHOTO # 3: PRE- AND POST-DRILLING ........................................................................... 5 FIGURE 3-5 PHOTO #4: PRE-AND POST-DRILLING ............................................................................. 6 FIGURE 3-6 PHOTO # 5: PRE- AND POST-DRILLING ........................................................................... 6 FIGURE 3-7 TYPICAL TRUCK MOUNTED DRILL VEHICLE ............................................................... 24 FIGURE 3-8 ATV MOUNTED DRILL VEHICLE .................................................................................. 25 FIGURE 3-9 TRACK MOUNTED DRILL VEHICLE .............................................................................. 26 FIGURE 3-10 PLATFORM MOUNTED DRILL RIG ................................................................................... 27 TABLES TABLE 3-1 NUMBER OF BOREHOLES AND MILES OF OVERLAND TRAVEL ON BLM AND USFS LANDS BY FIELD OFFICE AND FOREST ................................................................................................... 7 TABLE 3-2: TEMPORARY GROUND DISTURBANCE BY LAND OWNERSHIP (ACRES) .............................. 8 APPENDICES ATTACHMENT G-1 SUMMARY GEOTECHNICAL EXPLORATION PLAN .............................................. 43 ATTACHMENT G-2 PRELIMINARY GEOTECHNICAL EXPLORATION SCHEDULE ................................ 44

POWER ENGINEERS, INC. GEOTECHNICAL INVESTIGATION PLAN OF DEVELOPMENT

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE iii

ACRONYMS AND ABBREVIATIONS ATV All-terrain Vehicle BIA Bureau of Indian Affairs BLM Bureau of Land Management BMP Best Management Practices CFR Code of Federal Regulations CPT Cone Penetration Test EPM Environmental Protection Measure FEIS Final Environmental Impact Statement FWS United States Fish and Wildlife Service HSA Hollow-stem auger kV kilovolt NEPA National Environmental Policy Act ODEX Brand name for Under-reamer type drilling POD Plan of Development psi Pounds per square inch ReMi Refraction micro-tremor ROD Record of Decision ROW right-of-way SPCC Spill Prevention, Control, and Countermeasure USFS United States Forest Service VW Vibrating Wire

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 1

1.0 INTRODUCTION 1.1 Geotechnical Plan of Development Purpose and Strategy The Bureau of Land Management (BLM), per Title 43 Code of Federal Regulations (CFR) 2804.25(b), has required that a Plan of Development (POD) be prepared in support of the Energy Gateway South Project (Project) that explains in detail how the Project will be developed. The POD is being developed in coordination with cooperating agencies and PacifiCorp. 1.1.1 NEPA POD

The NEPA POD is based on information and data documented in the Final Environmental Impact Statement (FEIS). The Geotechnical Investigation POD is an appendix to the NEPA POD which will be included in the Bureau of Land Management (BLM), United States Forest Service (USFS), and Bureau of Indian Affairs (BIA) Records of Decision (ROD) and an enforceable condition of the BLM right-of-way grant, the USFS special use permit, and the BIA encroachment permit and grant of easement. The BLM and USFS have determined that the POD will be developed in two phases: (1) the first phase is referred to as the “NEPA” (National Environmental Policy Act) POD and (2) the second phase is referred to as the Construction POD. The NEPA POD is being developed by PacifiCorp, in collaboration with the agencies, based on the information and data documented in the Final Environmental Impact Statement (EIS) and minor refinements made by PacifiCorp and agencies. The NEPA POD will be completed to the satisfaction of the BLM, USFS, and BIA to enable the BLM, USFS, and BIA to approve and sign the RODs. The Construction POD will be comprised of refined NEPA POD information and data that is based on detailed engineering and the results of environmental field surveys conducted after the execution of the RODs. Information in the Construction POD may be modified and/or updated (from the NEPA POD) as PacifiCorp refines the design of the Project and/or as a result of changes in applicable agency requirements. As PacifiCorp refines the design of the transmission line, access roads, and other ancillary facilities, the refined detail will be incorporated into the mapping contained in the Construction POD. Refinement of environmental locational data and mitigation and environmental protection measures (EPM’s) resulting from environmental field surveys will also be incorporated into the Construction POD mapping. 1.1.2 Geotechnical Investigation Plan of Development Geotechnical investigations are a required step in the Project construction process that provides necessary information to be able to complete detailed engineering and design of the transmission line, access roads, substations and series compensation stations, and other facilities. Therefore, PacifiCorp, in coordination with the BLM, USFS, and BIA has developed an implementation strategy that includes the preparation of a separate Geotechnical POD that is included as Appendix G in the NEPA POD. The Geotechnical Investigation POD describes the geotechnical investigation program and includes detailed information on the drilling program, location of boreholes, drilling equipment to be used at each borehole, and access to the boreholes. Volume II, Map Set 1-Project Environmental Features and Map Set 2-Key Mitigation and Reclamation Practices of the NEPA POD shows the borehole locations, access, and other pertinent Project and environmental information. The Geotechnical Investigation POD also describes and calculates the location and amount of anticipated disturbance associated with drilling activities at each bore location. Disturbance for the Project was also calculated in the EIS and NEPA POD based on a predictive model for the transmission line. Actual disturbance associated with the geotechnical program will be wholly contained within the disturbance associated with construction of the Project as described in the EIS and NEPA POD. The Geotechnical Investigation POD identifies environmental protection measures that are to be applied specifically to the implementation of the geotechnical investigation program. The application of geotechnical investigation program specific environmental protection measures will minimize geotechnical investigation

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 2

specific impacts on environmental resources. As applicable, the design features and selective mitigation measures identified in the NEPA POD will apply to the geotechnical investigation program as well and are identified in NEPA POD Tables 4-1 and 4-2. Design features are measures and practices that are incorporated into the Project description, including siting, to reduce environmental impacts. The environmental resource clearance surveys, including survey methodologies, that are required to be conducted prior to the initiation of geotechnical exploration and drilling activities are detailed in Appendix B-1 of the NEPA POD. 2.0 PURPOSE OF THE GEOTECHNICAL INVESTIGATIONS 2.1 Purpose and Need The purpose of the geotechnical investigations is to perform tests to collect hydrogeologic and geotechnical soil properties and geophysical data to provide information for detailed transmission line, substations, and series compensation stations engineering and design. Geotechnical investigations provide critical data that will be incorporated into structure foundation design and the Project construction bid package. Information obtained from the geotechnical investigations will help to ensure the Project is designed and constructed to be safe, reliable, and cost effective. Access roads and overland access routes used for the geotechnical investigations will be access routes proposed for construction of the transmission line and approved for the geotechnical investigations in the BLM, USFS, and BIA RODs; and the BLM right-of-way grant, USFS special-use authorization, and BIA encroachment permit and grant of easement. 3.0 GEOTECHNICAL EXPLORATION DESCRIPTION, STANDARDS AND REQUIREMENTS 3.1 Geotechnical Exploration Plan 3.1.1 General Requirements The geotechnical investigation will consist of geotechnical drilling, or geophysical surveys, of approximately 377 testing locations which are identified and described in Attachment G-1: Summary Geotechnical Exploration Plan and shown on maps in Volume II, Map Set 1 and Map Set 2 of the NEPA POD. It will not be necessary to drill and test soil conditions at every structure location. The borehole locations identified in Attachment G-1: Summary Geotechnical Exploration Plan were initially selected based on PacifiCorp’s Transmission Construction Standard TA 071: Transmission Structure Foundation Design Criteria for Towers and Monopole Structures (TA 071), and incorporates the results of a preliminary desktop geotechnical report that identified expected geological conditions and associated hazards. Additional details regarding the selection of geotechnical testing locations are discussed in Section 3.2: Description and Identification of Geotechnical Exploration Sites, Access Routes and Temporary Disturbance. Geotechnical site investigations, laboratory testing and engineering analyses will be completed to determine the engineering properties of the soil and bedrock, and will be used to design the foundations for the transmission line towers and associated equipment. In addition, geotechnical evaluations are required at the Clover Substation and the two series compensation station sites to quantify subsurface conditions, determine engineering properties of the soil for foundation design, and to provide recommendations for site development. The geotechnical site investigations will consist of drilling borings from which soil and/or bedrock samples will be taken for laboratory testing and analysis. The boring depths will typically be 50 to 60 feet below the ground surface. The borehole depth may exceed 60 feet if soil conditions dictate. The drilling equipment needed to perform the drilling and sampling activities may include truck-mounted, track-mounted, or all-terrain mounted drilling rigs; water truck; 4-wheel drive support vehicle used to haul equipment, supplies, and personnel; and a 4-wheel drive vehicle for the geotechnical engineer. The type of drilling vehicle used depends on the accessibility of

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 3

borehole locations and the practicality of using specific drilling techniques at each location. The drilling method options are described in detail in Section 3.4.1: Geotechnical Drilling Methods. Drilling vehicle types are described in Section 3.5: Drill Vehicle Types. The borings will be approximately 6 to 8 inches in diameter and may be advanced with continuous flight hollow-stem auger, mud rotary, air rotary, sonic, down-hole air hammer, or Cone Penetration (CPT) techniques. Descriptions of each possible drilling method are provided in Section 3.4.1. Where bedrock is encountered, standard coring techniques will be used. Samples will be collected by driving a sampling device into the undisturbed soils just below the augers. Where necessary, rock core samples will also be taken using a rock coring barrel. Upon completion and before leaving each site, the soil boring will be backfilled to existing grade with the cuttings removed during drilling. No open holes will be left unattended, and all holes will be fully backfilled before moving to the next boring. 3.1.2 Temporary Ground Disturbance Temporary ground disturbance associated with the implementation of geotechnical investigation activities will consist of two primary components, which are the boring work areas and the access routes required to reach the boring work areas. The temporary disturbance of the boring work areas and access routes will include overland travel and the subsequent crushing of vegetation as the drilling equipment moves overland to and from the borehole location, and vegetation removal at each borehole drilling site, if required. All disturbance associated with the geotechnical investigation program shall be contained completely within the transmission line construction area analyzed for disturbance within the Project EIS and within the ROW pursuant to the ROD’s issued for BLM right-of-way grant, the USFS special use permit, and the BIA encroachment permit and grant of easement. 3.1.2.1 Boring Work Areas A temporary work area of approximately 40 feet by 40 feet (1,600 square feet or 0.037 acre per drill site) will be required at each boring location (Figure 3-1: Geotechnical Boring Work Area). The boring will be fully contained within the temporary work area. Surface disturbance within the temporary work area may occur as a result of moving the drilling vehicles, support vehicles, and associated equipment. Additional foot traffic will also occur around the drill vehicles as the drill crew moves between the drill and support vehicles, causing temporary disturbance. The top 6 to 8 inches of soil material of the borehole will be stripped and set-aside. The actual ground disturbance where bare soil will be exposed will be contained within an approximately 3-foot diameter circle relative to the borehole. At the completion of the boring, the borehole will be backfilled and compacted, and the previous stripped topsoil will be placed over the backfilled boring to existing grade. The average estimated drilling time at each site is approximately one-half day, although conditions in the field may increase and/or decrease the actual required time. Figures 3-2 through 3-6 show photographs of typical site conditions before drilling and typical site conditions after drilling. The borehole locations in the photographs are marked with an orange stake. In the event high groundwater conditions are encountered during drilling, temporary piezometers may be installed and revisited periodically to collect groundwater depth readings throughout the year. Groundwater level information will be used to understand seasonal groundwater elevation changes and for foundation design considerations. In the event artesian groundwater conditions are encountered, vibrating wire (VW) piezometers (also known as pressure transducers) may be installed. Proposed borehole locations where artesian conditions may exist will be assessed in the field during borehole/access road field verification activities prior to drilling. The equipment used for temporary piezometers typically consists of a 2 to 4-inch diameter PVC pipe that is slotted/screened across the anticipated groundwater surface elevation. The piezometer is held in place by backfilling drill cuttings around the pipe and groundwater levels are collected manually through the use of an

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 4

electronic groundwater level meter. The equipment used for piezometers with a longer monitoring time frame, typically consist of a pressure transducer with signal cables that is placed within a 2 to 4-inch PVC pipe that is slotted/screened across the anticipated groundwater surface elevation, or installed using a direct-push technique utilized by Cone Penetration Testing (CPT) equipment. The piezometer is held in place by backfilling the borehole around the PVC pipe with drill cuttings and then grouting the upper few feet of the borehole with bentonite cement slurry. The signal cables would protrude above the ground surface 2 to 5 feet and would be coiled and secured at the soil surface to the survey lathe. Depending on site conditions more than one VW piezometer may be installed. Disturbance would be minimal as the pressure transducer is placed in the existing borehole. Only the survey lathe, top of the PVC pipe, and cables would be visible at the ground surface. The above-ground end of the PVC pipe will be covered with a vented and secured cap to prevent wildlife mortality. Temporary piezometers would require site visits to manually record groundwater levels on an as-needed basis determined by the geotechnical engineer or geologist. The more permanent VW piezometers would require site visits once per month for up to one year, and would consist of connecting a data logger to the pressure transducer cables to take readings. At the end of the monitoring program the lathe and VW piezometer would be removed. The PVC pipe would be abandoned in place by backfilling with bentonite cement slurry to prevent potential cross-contamination between the ground and subsurface waters. The upper few feet of the original borehole would then be covered with topsoil to existing grade. Temporary surface disturbing activities will include driving to and from the drill site, borehole drilling, backfilling the borehole, and driving to the site for subsequent monitoring where piezometers may be installed.

FIGURE 3-1 GEOTECHNICAL BORING WORK AREA

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 5

Pre-Drilling Post-Drilling FIGURE 3-2 PHOTO #1 PRE-AND POST DRILLING

Pre-Drilling Post-Drilling FIGURE 3-3 PHOTO #2: PRE- AND POST-DRILLING

Pre-Drilling Post-Drilling FIGURE 3-4 PHOTO # 3: PRE- AND POST-DRILLING

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 6

Pre-Drilling Post-Drilling FIGURE 3-5 PHOTO #4: PRE-AND POST-DRILLING

Pre-Drilling Post-Drilling FIGURE 3-6 PHOTO # 5: PRE- AND POST-DRILLING

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 7

3.1.2.2 Access Routes Access to the boreholes would be made along the Agency Preferred Alternative analyzed in the Project EIS and issued by the BLM, USFS, and BIA in the right-of-way grant (BLM), special-use authorization (USFS), and encroachment permit and grant of easement (BIA). Existing access roads and overland access routes used for the geotechnical investigations will be access routes proposed for transmission line construction and approved for the geotechnical investigations in the BLM, USFS, and BIA RODs and BLM right-of-way grant, USFS special-use authorization, and BIA Encroachment Permit and Grant of Easement. Therefore, all disturbance associated with the geotechnical investigation program will be contained completely within the area analyzed for disturbance associated with the transmission line construction. Grading for access to geotechnical investigation sites will not be required. In areas where conventional drill or exploration vehicles cannot access exploration sites due to unforeseen constraints not previously identified during access field review and confirmation, an alternate drill rig type, helicopter inserted platform, man portable or similar will be used. However, due to expense these methods have been minimized during planning. Access to each drill site was considered in selecting borehole locations. Locations that could be accessed with existing roads were selected where available to minimize the length of overland travel. Access roads and overland travel routes as designated for the final BLM right-of-way grant, USFS special use authorization, and BIA encroachment permit and grant of easement would be used exclusively. Table 3-1: Number of Boreholes and Miles of Overland Travel on BLM Lands by Field Office summarizes the number of boreholes and the approximate travel distance (in miles) for overland travel on BLM lands by field office and Forest. TABLE 3-1 NUMBER OF BOREHOLES AND MILES OF OVERLAND TRAVEL ON BLM AND USFS LANDS

BY FIELD OFFICE AND FOREST AGENCY NUMBER OF BOREHOLES

APPROXIMATE # OF MILES OF OVERLAND TRAVEL

BLM Field Office Rawlins

49 81.0 White River

13 19.5 Little Snake

15 36.7 Vernal

57 56.3 Price

1 2.6 Salt Lake

4 2.1 Richfield

0 0.7 Filmore

8 2.1 Subtotal (BLM)

147 200.9 National Forest

Uintah-Wasatch-Cache 12 16.0 Manti-LaSal 4 6.6

Subtotal (USFS) 16 22.6

Total BLM/USFS 163 223.5

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 8

In most cases the drill and support vehicles will make one trip in and one trip out to the boring location. In some cases the water truck or other vehicles may come and go from the boring location to deliver water or other supplies. Each drill site may be visited up to five times; once for staking, a second time for environmental clearance surveys, a third time to check access prior to drilling, a fourth time for drilling activities, and a fifth time if reclamation and stabilization of the site is required. Additional visits may be required for groundwater monitoring and abandonment purposes in the event a piezometer is installed at the borehole location. The estimated amount of temporary ground disturbance for the proposed drilling sites by landownership is shown Table 3-2: Temporary Ground Disturbance by Land Ownership. TABLE 3-2: TEMPORARY GROUND DISTURBANCE BY LAND OWNERSHIP (ACRES) BLM USFS State Private Tribal Total Number of Drilling Sites 147 16 41 171 2 377 Temporary Disturbance (0.037 acre per drilling site)

5.439 ac. 0.592 ac. 1.517 ac. 6.327 ac. 0.074 ac. 13.949 ac.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 9

3.1.3 Drilling Equipment Staging All drilling equipment will be staged within the approved Project right-of-way. No site specific staging areas are proposed within or outside of the Project right-of-way. Generally, the drilling vehicles, water truck, and any other related equipment would be left at the last completed boring location or moved to the next boring location. Drill crews would travel to and from the boring location by pick-up or 4-wheel drive vehicles. 3.2 Description and Identification of Geotechnical Exploration Sites, Access Routes, and Temporary Disturbance This section provides an overview of the geotechnical exploration site locations and access identified in Attachment G-1 and shown in Volume II, Map Set 1 and Map Set 2 of the NEPA POD. Criteria for selection of geotechnical exploration site locations and access routes are provided as well as a description of typical pre-drilling site conditions and post drilling site conditions. 3.2.1 Overview of Borehole Site Locations and Selection Criteria A list of the preliminary borehole locations and access routes (based on TA 071 criteria, a desktop review, and field verification activities completed in the summer of 2015) are provided in Attachment G-1 and shown on maps in Volume II, Map Set 1 and Map Set 2 of the NEPA POD. The proposed access routes and classification criteria are described below in Section 3.2.2. The majority of the borehole locations provided in Attachment G-1 are at planned structure locations that may change pending environmental resource review. Due to access constraints, some boreholes are not located at structure locations; however they are still located within the disturbance associated with construction of the project. The anticipated access routes, equipment types, and disturbance identified in Attachment G-1 were field verified where possible; however they should be considered approximate as field conditions affecting accessibility can change prior to the initiation of drilling activities. The borehole locations were selected based on PacifiCorp standard TA 071, the results of a preliminary geotechnical report that identified expected geological conditions and associated hazards, and field verification activities at select locations. Per TA 071, geotechnical borings shall comply with the following requirements and scenarios:

1. Maximum boring spacing equal to or less than 3 miles. 2. If a geotechnical engineer anticipates or evaluates a change in foundation type within the 3-mile boring

spacing due to significant change in soil and/or subsurface conditions (groundwater or geologic conditions), additional borings within the 3-mile section shall be conducted to evaluate the foundation parameters and constructability of the foundations.

3. At least one boring shall be conducted at every angle structure (8 degrees or greater was selected for this project) and dead end structure within the proposed transmission line alignment.

4. If side slopes of the boring locations are greater or equal to 25 percent, borings shall be moved to a relatively flat portion of the proposed alignment. The geotechnical engineer shall verify that the soil conditions within the steeper portion of the proposed transmission line will not significantly impact the design of foundations.

5. Additional borings may be deemed necessary by the geotechnical engineer. These additional borings may include the need to verify shallow bedrock and/or areas with known geological hazards in order to verify subsurface conditions for design purposes.

A total of 377 preliminary boreholes are identified in Attachment G-1, however it is anticipated that this number may be increased or reduced as additional access is granted on private property and/or alternative geotechnical exploration techniques are evaluated and considered for landslide areas. As shown in Attachment G-1, borehole identification numbers are currently based on tower structure number. Attachment G-1 includes location and land

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 10

ownership information as well as anticipated access type, associated link, disturbance, and drilling equipment and drilling method for each borehole location. Distance of overland drive and crush, and vegetation clearing requirements for each boring is also provided. If a boring location is in an area determined to contain sensitive resources, one of the following options will be used as appropriate, to avoid or mitigate impacts to the resource; 1) Monitor borehole during drilling activities, 2) Adjust drilling date outside of any seasonal restrictions, 3) Use alternative access or drilling type, 4) Relocate borehole, and 5) Abandon the borehole location. A geotechnical exploration option in some environmentally sensitive areas in select geologic settings would be to complete less invasive ReMi geophysical surveys. These surveys can be conducted in environmentally sensitive areas (e.g. sensitive plant or wildlife habitat areas, significant cultural resource areas), in remote areas that cannot be easily accessed by a drill vehicle, in areas of highly erosive soils or fragile locations that are subject to ponding, compaction or extensive removal of protective ground cover resulting in long-term disturbance. Borehole locations where ReMi surveys are an option and appear to be more environmentally appropriate will be determined once drilling activities are initiated and final field conditions can be determined. ReMi testing provides an approximation of the subsurface conditions but is not an adequate alternative to drilling as the results from ReMi surveys must be correlated to a nearby boring in order to provide reliable design parameters. Pending sensitive resource review, and depending on the total number of boreholes that are finally proposed, it is anticipated that the geotechnical investigation will be completed in approximately two field seasons. The first field season in which geotechnical investigations are to occur is scheduled to begin after the BLM right-of-way grant, USFS special-use permit, and BIA encroachment permit and grant of easement are granted. The drilling priority for each borehole will be shown in Attachment G-1 upon environmental resource review and final field condition verification. The drilling schedule is dependent primarily on environmental clearance survey completion, location and extent of required surveys, and the availability and number of contracted drillers during the time of drilling. PacifiCorp currently anticipates using more than one geotechnical firm. The type of drilling vehicle used will depend on the accessibility of borehole locations and the practicality of using specific drilling techniques at each location. The number of operational drill rigs at any one time is dependent on schedule urgency, however it is anticipated that up to four drill crews may be in operation at once. A typical drill crew consists of one drill rig operator, and one to two helpers. The equipment for each drill crew may include truck-mounted, track-mounted, or all-terrain mounted drilling rigs; water truck; 4-wheel drive support vehicle used to haul equipment, supplies, and personnel; and a 4-wheel drive vehicle for the geotechnical engineer. 3.2.2 Access Routes and Roads Principal access for geotechnical investigations will be by existing access roads or by overland travel. Potential access routes to the borehole locations and transmission line access were initially identified using aerial images in Google Earth and are provided in Volume II, Map Set 1 and Map Set 2 of the NEPA POD. Where possible, field verification was conducted for existing access roads, overland travel routes, and borehole locations during the summer of 2015. Not all access roads and borehole locations could be field verified due to right-of-entry permission constraints. Potential access roads were classified into categories based on interpretation of the aerial image and experience working in similar environments. Geotechnical exploration activities and transmission line construction have different access requirements. The following categories of road were identified for both geotechnical exploration activities and for transmission line construction:

• Existing Roads-No Improvement • Existing Road

o Improvements Required for transmission line construction o No Improvements required for geotechnical investigation

• New Roads-Bladed o Bladed for transmission line construction

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 11

o Overland (drive and crush) access for geotechnical investigation • New Roads-Overland

o Overland (drive and crush) access for transmission line construction o Overland (drive and crush) access for geotechnical investigation

• Temporary Road o Bladed to overland access for transmission line construction o Overland (drive and crush) access for geotechnical investigation

For the geotechnical investigations, and prior to any field verification of the access roads, “Existing Roads” are anticipated to be easily accessed by truck-mounted drilling rigs. “Existing Roads-Improvement Required” are anticipated to already provide access for either truck-mounted or tracked drilling rigs. “New Roads” are considered to require access via overland (drive/crush) techniques and therefore the use of tracked or all-terrain drilling rigs is anticipated, however truck-mounted drilling rigs may be used for overland travel depending on the terrain. New access roads as shown on Volume II Map Sets will only be used as overland access routes for geotechnical investigations. It should be noted that the classifications provided in Attachment G-1 are to be considered approximate as not all access roads and borehole locations were field verified due to right-of-entry permission constraints. In these cases, the access classifications are based on aerial imagery. In addition, field conditions affecting accessibility can change prior to the initiation of drilling activities. 3.3 Identification of Potential Geologic Hazards 3.3.1 Overview of Geologic Hazards A geologic hazard (or geohazard) is a geological condition that has the potential to cause structural damage. The presence of potential geohazards can therefore represent significant risks to a development project. Geohazards can be widespread phenomena that are influenced by both geological and environmental conditions, and involve short-term and/or long-term processes. Human activities can exacerbate existing geohazards and subsequently increase risk. While some geohazards occur on a relatively small scale, such as localized rock-fall events, larger geohazards can have devastating effects. The potential impacts of various geohazards should therefore be investigated as they can affect the overall planning and economics of a project. Geologic information is important in the early planning stages of a transmission line project because it can be used to avoid, or anticipate and plan for problematic areas. The failure to understand anticipated geologic conditions and understand the risk associated with the conditions can lead to costly transmission line redesigns and potential reroutes that could have been easily avoided in early planning stages. The review of geological hazards consisted of a preliminary geotechnical desktop study followed by field verification of select hazards in the summer of 2015. Due to the size and underground nature of most geohazards, not all geohazards can be field verified. The desktop study summarized surficial geology and geologic hazard information as it pertains to construction of the transmission line and planning of subsequent geotechnical field explorations along a two-mile buffer zone (corridor) on either side of the Agency Preferred Route. The desktop study was based only on published and available geological information so it should be considered limited. This information was compiled into a GIS database for analysis as it pertains to the Project. Information in the GIS database includes geologic maps, geohazards data, soils information, and Federal Emergency Management Agency (FEMA) data. Geological and geotechnical information within the four-mile corridor (two miles on each side of alignment) along the alignment was reviewed by link. The hazards were ranked using L-Low; M-Moderate; or H-High to indicate presence and/or impact as discussed below. While a desktop analysis can provide important information during initial project planning, all geologic conditions identified during desktop analysis should be confirmed via geotechnical investigations. The following is a general discussion of potential geohazards identified during the desktop analysis that may be encountered along the alignment.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 12

Slope Failure Landslides

Slopes may fail depending on topography (steep slopes), existing or proposed construction activities, geology, water content, the type of earth (soil) material involved, and local environmental factors including ground temperature, seismic activity, and ambient weather. For the desktop study, slope failure included landslides, mass wasting, and debris flow data from published sources as well as aerial imagery interpretations. The potential for failure can be identifiable, and therefore forewarning may be possible, but the actual timing of failure cannot be accurately predicted. Climate and seasonal changes may accelerate or slow the natural rate of slope failure through changes in precipitation and/or in the vegetation cover that binds loose slope material. Field investigation would be required to assess the risk associated with each suspect slope and its possible impacts on the alignment. Mapped landslide data was only available for the States of Wyoming and Utah. Potential landslides in Colorado were reviewed via aerial imagery as mapped landslide data was not available for review. Landslide risk ratings were categorized as follows:

Low (L): No landslides mapped in the area

Moderate (M): Landslides mapped within 2 miles, but away from alignment

High (H): Alignment traverses identified and/or mapped landslide(s)

Steep Slopes

Transmission line structures are typically not placed on steep slopes for constructability reasons, however, in certain cases construction in these environments is required. For the desktop study, the slope classifications were determined using a slope map and interpretations of aerial imagery and topographic maps. Steep slope risk ratings were categorized as follows:

L: 0 to 8 degrees M: 8-25 degrees H: Greater than 25 degrees

Expansive and Collapsible Soils The causes of soil expansion or collapse are related to the type of deposit including: soil type, structure, and density. Soils may form in-place by weathering of rocks, or they can be transported and deposited by gravity, water, or wind. A change in the moisture content of a soil can cause soils to swell or to lose strength and consolidate. The presence of expansive and collapsible soils can be detected by direct observation during geotechnical investigation activities and laboratory testing. Polygonal soil cracking (mudcracks) or popcorn texture in exposures is indicative of shrink/swell clayey soils. The phenomenon of hydrocompaction or collapsible soils often consist of loose, dry, low-density materials that collapse and compact under the addition of water or excessive loading. These soils are typically found in areas of young alluvial fans, debris flow sediments, and loess (wind-blown sediment) deposits. Soil collapse occurs when the land surface is saturated at depths greater than those reached by typical rain events. This saturation eliminates the bond holding the soil grains together. Collapsible soils are geologically young material, such as Holocene-age alluvial-fan and debris-flow sediments, and some windblown silts. In areas where expansive and/or collapsible soil are suspected and/or anticipated, a thorough field investigation program followed by subsequent laboratory testing program will be necessary to

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 13

further characterize the areas. Drilled pier foundations have been used in Utah, Colorado and Wyoming to reduce expansive soil damage; however foundations must be sufficiently imbedded below the zone of anticipated moisture fluctuation. Mapped expansive and collapsible soils data was only available for the State of Utah. Expansive and collapsible soil risk ratings were categorized as follows:

L: No expansive or collapsible soil mapped within 2 miles M: Expansive and/or collapsible soil mapped within two miles, but not along the alignment H: Alignment traverses mapped expansive and/or collapsible soils

Karst Features Karst features are distinctive surficial and subterranean features developed by solution of carbonate and other rocks characterized by closed depressions, sinking streams, and cavern openings. The term is typically used to define surface features derived by solution of carbonate rocks, but subsequent use has broadened the definition to include sulfates, halides, and other soluble rocks. The term has been expanded also to cover interrelated forms derived by solution on the surface in the subsurface. When used in its broadest sense, the term encompasses many surface and subsurface conditions that cause problems in engineering geology. Most of these problems are associated with subterranean karst and pseudokarst features that affect foundations, tunnels, reservoir tightness, and diversion of surface drainage (Davies, et. al, 1984). Pseudokarst Features

The USGS Digital Engineering Aspects of Karst Map identifies areas with known problems in engineering geology caused by karst and pseudokarst features in the United States. Pseudokarst is terrain with features similar to karst, but formed in nonsoluble rock, as by melting of permafrost or ground ice, collapse after mining, and by outflow of liquid lava from beneath its solidified crust. Pseudokarst features are extensive in some regions of the west and primarily exist throughout Wyoming, Colorado, and Utah in late Cenozoic basalt fields where lava tubes, fissures, open sinkholes, and caves formed by the extrusion of still-liquid lava. Lava pseudokarst features present problems in in foundations, abutments, and reservoir tightness. In addition, the tubes and related permeable rock often contain large quantities of water that may lead to flooding and slope stability problems in cuts and excavations. Pseudokarst features mapped within the vicinity of the Project specifically include fissures, tubes, and caves over 1,000 feet long that are 50 feet to over 250 feet in vertical extent and located in moderately to steeply dipping beds of carbonate rock. Pseudokarst feature risk ratings were categorized as follows:

L: No pseudokarst features mapped within 2 miles M: Pseudokarst features mapped within two miles, but not along the alignment H: Alignment traverses mapped pseudokarst features

Karst Engineering Issues

Mapped limestone (karst) data was only available for the State of Utah. Limestone (karst) risk ratings were categorized as follows:

L: No limestone (karst) features mapped within 2 miles M: Limestone (karst) features mapped within two miles, but not along the alignment H: Alignment traverses mapped limestone (karst) features

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 14

Seismicity and Earthquakes Seismic Zone

Seismicity is caused by complex regional tectonic processes that include movement along plates, faults, and uplifts. Seismicity is often closely linked to earthquakes and is responsible for their geographic and/or historical distribution. An earthquake is generally defined as a sudden motion or trembling in the Earth caused by the abrupt release of slowly accumulated strain. The most common types of earthquakes are caused by movements along faults. The United States Geological Survey (USGS) Earthquake Hazards Program is part of the National Earthquake Hazards Reduction Program (NEHRP), established by Congress in 1977 to monitor and report earthquakes, assess earthquake impacts and hazards, and research causes and effects of earthquakes. The program also developed probabilistic seismic hazards (PSH) maps that depict the levels of earthquake ground motion that have a 10% probability of being exceeded within 50 years. The measure of an earthquake’s ground motion is measured by peak horizontal ground acceleration, which is expressed as a proportion of the acceleration caused by gravity. The peak ground acceleration represents probabilistic estimates of the intensity of ground motion that is likely to occur as a result of reasonably foreseeable earthquake events on active faults. The values for seismic acceleration as a percentage of gravitational acceleration (g) for each link were evaluated. The acceleration values were obtained from a digital overlay of the USGS Seismic Hazard Map showing the peak acceleration with 10% probability of exceedance in 50 years. To assist in correlating acceleration to our environmental surroundings, the USGS Instrumental Intensity table lists relative scale of acceleration to instrumental intensity, perceived shaking, and potential damage. Potential damage categories include “None, Very Light, Light, Moderate, Moderate to Heavy, Heavy, and Very Heavy.” Quaternary Faulting

Faults are structural features (fractures) in the Earth’s crust where seismic activity has caused displacement. Natural causes are seismic/tectonic activity and the compressive forces in the Earth’s crust. Strains increase with time until the crust ruptures and adjacent blocks slip and translate vertically, horizontally, and/or diagonally. Removing large qualities of subsurface fluid can contribute to stress-strain adjustment in subsurface soil and rock. Typically, there are five common fault classifications: Normal, Reverse, Strike Slip, Oblique, and Overthrust faults. The most common are usually normal and reverse faulting; however, in many of the basin formations, overthrusting is also common. Faults vary in age and are usually visible on the surface by lineations, truncated ridges, faceted spurs, horst and graben landforms, rejuvenated streams, blocked or truncated streams, and step scarps. Buried and unobservable faults can also be identified by seismological data (alignment of epicenters). Displacements on individual faults range from hundreds to many thousands of feet; however, the displacements usually do not occur in single events. Seismic studies indicate that the minor slips on faults only relieve a small fraction of the accumulated strain. Older faults have had time to adjust to build up strain; however, the younger age faults (Quaternary) are associated with most geohazard studies. Active faults are defined as those that have moved or slipped in the Quaternary age (the last 1.8 million years) and are often linked to recent and future earthquakes. Faults less than 15,000 years old are considered active for this study. Quaternary fault risk ratings were categorized as follows:

L: No mapped faults mapped faults within two miles M: Mapped faults within two miles, but not traversed by the alignment H: Alignment traverses mapped faults

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 15

Liquefaction

Liquefaction is a dynamic loading and/or transient shear wave phenomenon that occurs in saturated sands. If a saturated soil or near saturated soil is subjected to ground vibrations (dynamic loading) it tends to compact and decrease in volume. If the fine grained soil cannot drain rapidly enough, the decrease in volume results in an increase in pore pressures. When the pore pressure increases until it is equal to the overburden confining pressures, the effective stress between soil particles becomes zero resulting in a complete loss of shear strength, and advances into a liquefied state. Fine grained silts and sands are the most susceptible soils, especially along rivers, streams and lake shorelines, as well as in some ancient river and lake deposits. Even though fine sands are documented as the most susceptible to liquefaction, it has been recently documented that gravel deposits are susceptible to liquefaction. In general, two conditions must exist for liquefaction to occur: (1) the soil must be susceptible to liquefaction (loose, water-saturated silty and/or sandy soil, typically between 0 and 30 feet below the ground surface) and (2) ground shaking (seismic event) must be strong enough to induce liquefaction of the soil. Geotechnical investigations and field knowledge of the local geology and subsurface soil and water conditions are an important component of further characterizing areas susceptible to liquefaction. No publically available mapping of liquefiable soils was available along the alignment. Due to the lack of available data and limited number of areas documented with shallow groundwater occurrences, the following classification was used for identifying liquefaction risk; however, the results of the geotechnical investigation will be required to properly characterize liquefaction potential. Liquefaction risk ratings were categorized as follows:

L: Low potential for shallow groundwater M: Moderate potential for shallow groundwater H: High Potential for shallow groundwater

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 16

Groundwater and Flooding Shallow Groundwater

Water in saturated zones beneath the land surface is typically referred to as groundwater. It is regarded as shallow when it is located less than approximately 30 feet below the ground surface. Most shallow groundwater occurs in basin valleys, downstream of earth dams, along seasonal water courses, rivers, and near swamp/marshy areas and lakes. Unconsolidated deposits that are saturated at shallow depths often present problems for land development in that it causes unstable excavations and foundations. The water in shallow saturated zones is replenished by infiltration from streams, lakes, precipitation, lateral subsurface flow from adjacent higher ground-water areas, and upward leakage of underlying confined water. The shallowest groundwater is generally found in stream valleys and in the center of basins where upward leakage from underlying artesian systems is greatest and potentiometric surfaces are highest. In addition, shallow groundwater is a prerequisite for liquefaction. Shallow groundwater levels are a dynamic process and fluctuate daily, seasonally, annually, and over longer periods in response to a variety of conditions. Topographic and geologic information typically provide a check on the distribution of shallow groundwater areas. National Resource Conservation Service (NRCS) Soil Survey mapping and FEMA Floodplain Maps were reviewed to help identify the geohazard risk along the proposed corridor. In addition, the annual reports on groundwater conditions in each state prepared by the USGS and State Division of Water Resources help with historical fluctuations in shallow groundwater. Shallow groundwater will likely be confined to Colorado Plateau and Middle Rocky Mountain and basin valley-bottom areas between plateaus and ranges where rivers and streams intersect the alignment. Shallow groundwater risk ratings were categorized as follows:

L: No shallow groundwater mapped within two miles M: Shallow groundwater mapped within two miles, but not traversed by the alignment H: Mapped shallow groundwater traversed by the alignment

Flooding

Flooding can destabilize the land surface and potentially damage towers and access roads. Flooding denotes a progressive abnormal increase in the elevation of the surface level of open channel flow until it reaches a level in excess of its normal maximum height and subsequent inundation of areas which are not normally submerged. The episodic behavior of an open channel that may be considered in the flooding process is then termed “flood event” and typically takes place with a certain period of time. The most common flood environment within the proposed corridor will be when open channels such as rivers and streams overflow their banks due to excessive rain events, high rate of snow melt, and overland flow due to denuded and/or removal of vegetation, usually from fires. Flooding is classified according to its likelihood of occurring in a given time period. A hundred-year flood event is a relatively large and often destructive event that would theoretically be expected to happen only once every century. In reality, this classification means there is a one-percent chance that such a flood event could happen in any given year. Flash flooding can occur within a few minutes or hours of excessive rainfall and is common in alpine regions of all three states. The geohazard potential for flooding used in the desktop study was based on FEMA 100-year floodplain designation maps (where available), aerial imagery interpretation, and limited field evaluation. Flood risk ratings were categorized as follows:

L: No mapped or interpreted floodplains within two miles M: Mapped or interpreted floodplains within two miles, but not traversed by the alignment H: Mapped or interpreted floodplains traversed by the alignment

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 17

3.3.2 Geologic Hazard Locations 3.3.2.1 Wyoming Links W15, W21, W35, W36, W30, W32, W101, W125, W108, W116, W113, W302, and W411are generally located within the Wyoming Basin physiographic province which is characterized by broad, arid intermontane basins interrupted by hills and low mountains. Topography is gently sloped in the basins, but becomes more dramatic and steep near local uplifts and surrounding mountains. Escarpments, found on surrounding hills and low mountains in the province, expose geologic layers, some of which are brightly colored. Hogback ridges and cuestas (long ridges with a steep escarpment on one side and gentle slope on the other) are additional distinctive landscape features found in the province. The lithology along the alignment generally consists of sedimentary rocks ranging in age from Jurassic to Tertiary. The bedrock is generally covered with veneers of recent alluvium, colluvium and unconsolidated slope wash material. Landslides mapped within two miles of the alignment (“Moderate” hazard ranking), were documented near Links W15, W21, W30, and W113. No evidence of landslides was observed along the alignment in the areas visited during field verification activities. Steep slopes greater than 25 degrees (“High” hazard ranking) exist along the alignment at Links W21, W32, and W113 while slopes between 8 and 25 degrees (“Moderate” hazard ranking) exist along Links W35, W36, W30, W302, and W411. No data was available for expansive and collapsible soils in the State of Wyoming. However, Hydrologic Soil Group D soils, which have the potential to contain expansive soils, are documented within two miles (“Moderate” hazard ranking) of the majority of the Links in Wyoming. The alignment traverses (“High” hazard ranking) mapped pseudokarst features at Links W15, W21 and W30. No evidence of karst features was observed along the alignment in the areas visited during field verification activities. No Quaternary faults were mapped within two miles of the alignment (“Low” hazard ranking). The alignment crosses seismic acceleration zones of 0.05 to 0.06 g, which correlates to “Very Light” potential damage according to the USGS. Approximately twelve seismic events are documented in this general area of Wyoming, with two events being located within two miles (“Moderate” hazard ranking) of Link W21. Shallow groundwater and potentially liquefiable soils are traversed by the alignment (“High” hazard ranking) at Links W15, W21, and W116, and are also located within two miles (“Moderate” hazard ranking) of Links W35, W30, and W302. Areas with potential shallow groundwater were observed along these Links at stream/river crossings during field verification activities. The alignment crosses (“High hazard ranking) mapped and/or observed flood plains at Links W15, W21, and W116, and W113, and flood plains are within two miles (“Moderate” hazard ranking) of Links W35 and W30. Evidence of flash flooding and erosion was observed along Link W116 during field verification activities. 3.3.2.2 Colorado Links C31, C61, C71 are generally located within the Wyoming Basin physiographic province (described above) but unlike the description for Wyoming, the Project crosses increasingly dissected landscapes of hills and low mountains. Links C91, C94, C95, C175, C186, and C188 are located in the transition area into the Uinta Basin Section of the Colorado Plateau physiographic province which his characterized by increasingly dissected landscapes of hills and low mountains with plateaus containing sharp ravines, sparsely vegetated escarpments, and cliffs separated by broad basins. The lithology along the alignment generally consists of sandstone, shale, and limestone of Cretaceous to Tertiary age. No mapped landslides data was available for Colorado, however based on aerial imagery review, no landslides appear to be within two miles of the alignment (“Low” hazard ranking) and no evidence of landslides was observed along the alignment in the areas visited during field verification activities. Steep slopes greater than 25

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 18

degrees (“High” hazard ranking) exist along the alignment at Links C61, C91, C94, C95, C175, and C186, while slopes between 8 and 25 degrees (“Moderate” hazard ranking) exist along Links C31, C71, and C188. No data was available for expansive and collapsible soils in the State of Colorado. However, Hydrologic Soil Group D soils, which have the potential to contain expansive soils, are documented within two miles (“Moderate” hazard ranking) of Links C31, C71, C91, and C175. No pseudokarst features are mapped within two miles of the alignment (“Low” hazard ranking). No evidence of karst features was observed along the alignment in the areas visited during field verification activities. No Quaternary faults were mapped within two miles of the alignment (“Low” hazard ranking). The alignment crosses seismic acceleration zone of 0.05 g, which correlates to “Very Light” potential damage according to the USGS. Approximately fifteen seismic events are documented in this general area of Colorado, with one event being located within two miles (“Moderate” hazard ranking) of Links C186 and C188, and five events being located slightly greater than two miles (“Low” hazard ranking) of C188. Shallow groundwater and potentially liquefiable soils are traversed by the alignment (“High” hazard ranking) at Links C71 and C91, and are also located within two miles (“Moderate” hazard ranking) of Links C61, C94C186, and C188. Areas with potential shallow groundwater were observed along these Links at stream/river crossings during field verification activities. The alignment traverses (“High hazard ranking) mapped and/or observed flood plains at Links C71 and C91. Evidence of flash flooding and erosion was observed along Links C31, C61, C186, and C188 during field verification activities. 3.3.2.3 Utah Links U242, U280, U285, U300, and U400 are generally located in the Uinta Basin physiographic Section of the Colorado Plateau physiographic province (described above). Links U401, U404, U413, U418, U408, U411, U417, U445, U504, U508, U514, U516, U560, U530, U533, U539, and U460 are generally located in more mountainous terrain with characteristics common to both the High Plateaus of the Utah section of the Colorado Plateau physiographic province and the Middle Rocky Mountains physiographic province which is characterized by steep canyon walls with exposed rock outcroppings and a meandering band of riparian vegetation. Links U621, U625, U638, U639, U650, U640_345, U642_345, U643_345, and U644_345 are generally located at the beginning of the Great Basin section of the Basin and Range physiographic province which is characterized by sequences of narrow faulted mountain chains and flat arid valleys or basins. The lithology along the alignment is diverse and generally consists of Tertiary age sandstone, shale, and limestone, shale of the Green River Formation, sandstone, siltstone and shale of the Uinta Formation, shale of the Marcos and Morrison Formations, sandstone from the Morrison, Cedar Mountain, and Dakota Formations, shale of the Mancos Formation and Quaternary age alluvium, colluvium and stream deposits. Multiple landslides have been mapped across the mountainous regions of Utah. The alignment traverses (“High” hazard ranking) at Links U417, U445, U508, U514, U516, U530, U539, U460, U621, U625, U638, U639, and U650. Landslides mapped within two miles of the alignment (“Moderate” hazard ranking), were documented near Links U300, U413, U418, U408, U411, U504, U560, and U533. Evidence of landslides was observed along the alignment in the areas visited during field verification activities. However, due to the size and age of some landslides, it was not possible to determine if the landslides were active or stable. Geotechnical investigations will be required to determine slope stabilities. Steep slopes greater than 25 degrees (“High” hazard ranking) exist throughout all of the Links in Utah, with the exception of slopes between 8 and 25 degrees (“Moderate” hazard ranking) at Links U242and U560, and slopes between 0 and 8 degrees (“Low” hazard ranking) at Links U280, U285, U640_345, U642_345, U643_345, and U644_345. Mapped data was available for expansive and collapsible soils in the State of Utah. The alignment appears to traverse (“High” hazard ranking) mapped collapsible and expansive soils at Link U650. Mapped expansive soils

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 19

are within two miles (“Moderate” hazard ranking) of Link U639. In addition, Hydrologic Soil Group D soils, which have the potential to contain expansive soils, are documented within two miles (“Moderate” hazard ranking) of Links U242, UU280, U285, U300, U400, U401, U404, U413, U408, U41, U640_345, U642_345, U643_345, and U644_345. The alignment traverses (“High” hazard ranking) mapped pseudokarst features at Links U460, U640_345, and U642_345, and mapped pseudokarst features are located within two miles (“Moderate” hazard ranking) of Links U650, U643_345, and U644_345. The alignment traverses (“High hazard ranking) karst engineering issues related to limestone at Links U621, U625, and U638, and limestone (karst) is mapped within two miles (“Moderate hazard ranking) of Link U460. No evidence of karst features was observed along the alignment in the areas visited during field verification activities. The alignment traverses (“High” hazard ranking) mapped Quaternary faults at LinksU530, U650, U640_345, U642_345, and U643_345, and mapped Quaternary faults are located within two miles (“Moderate” hazard ranking) of Links U639 and U644_345. The alignment crosses seismic acceleration zones ranging from 0.05 to 0.15 g, which correlates to “Very Light” to “Light” potential damage according to the USGS. Numerous seismic events are documented in this general area of Utah, with two events being located within two miles (“Moderate” hazard ranking) of Link U242, and numerous events being located slightly greater than two miles of the majority of the alignment. Shallow groundwater and potentially liquefiable soils are traversed by the alignment (“High” hazard ranking) at Links U242, U280, UU285, U300, U400, U650, U640_345, U642_345, U643_345, and U644_345, and are also located within two miles (“Moderate” hazard ranking) of Links UU560. Areas with potential shallow groundwater were observed along these Links at stream/river crossings during field verification activities. The alignment traverses (“High hazard ranking) mapped and/or observed flood plains at U242, U280, U285, U300, U400, U650, U640_345, U642_345, U643_345, and U644_345, and mapped and/or observed flood plains are located within two miles (“Moderate” hazard ranking) of Link U560. Evidence of flash flooding and erosion was observed along Links U242 and U280 during field verification activities. 3.3.3 Conclusions The Project traverses mapped landslide areas in the State of Utah, and landslides are mapped within two miles of the alignment in Wyoming. Aerial imagery review indicates landslides along the alignment are not a concern in Colorado, however no mapped landslide data for Colorado was available for review. Construction of the Project could potentially contribute to destabilization of slopes and/or the re-activation of landslide deposits. While avoidance of these areas is preferred, engineered solutions and micrositing may be used to reduce impacts to existing conditions and enhance constructability in this type of geologic environment. A landslide evaluation will be required to determine both slope stability and whether or not a landslide is active vs. inactive. Results of this landslide evaluation, in combination with results of the geotechnical investigation, will be used for foundation and roadway design where alternative foundation and access road types may be required in landslide prone areas. While an assessment specific to landslides and slope stability has not yet been conducted, geotechnical boreholes have been placed at all structure locations located within mapped landslide areas in anticipation that site-specific solutions may be required. Once the geotechnical investigation commences and new, site-specific information becomes available, geotechnical borings may be added and/or removed as needed. The Project is not anticipated to impact faults, earthquakes, or liquefaction, however these hazards could directly or indirectly affect the construction, operation, and maintenance of the project so they must be considered during Project design. The desktop evaluation of expansive and collapsible soils, karst and pseudokarst features, Quaternary faulting, liquefaction potential, shallow groundwater conditions, and flooding potential was used in deciding where to place boreholes for future geotechnical investigation. Areas where these hazards are likely to occur will therefore be evaluated during the geotechnical investigation and results of the geotechnical investigation will be incorporated into final Project design. In the event that results of the geotechnical investigation warrant further exploration, additional geotechnical borings may be required.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 20

3.4 Geotechnical Exploration Methods Geotechnical exploration for this Project would consist primarily of geotechnical drilling with some geophysical surveys and geologic hazard assessments. Each of these exploration methods are discussed below. 3.4.1 Geotechnical Drilling Methods Geotechnical drilling may be accomplished using a variety of drilling methods, including hollow stem augers (HSA), mud rotary, continuous diamond coring, air hammer (e.g., overburden drilling with eccentric bit or ODEX), sonic drilling technologies, or by Cone Penetration Testing (CPT) equipment (also known as rigs), depending on the type of soil and rock expected within the completion depth of the borehole. The purpose of the geotechnical drilling will be to evaluate the soil conditions for the proposed transmission line structure foundations. The types of drilling rigs that may be used for the variety of drilling methods described below are described in Section 3.5 with photographs of typical drilling rigs shown in Figures 3-7 through 3-9. 3.4.1.1 Hollow Stem Auger Drilling HSA drilling consists of rotating a drill stem to advance a toothed bit into the subsurface materials. The materials are brought up from the borehole by the rotation of a continuous helical fin on the outside of the drill stem. The drill stem is added in pieces (flights) as the boring advances downward. This is a dry method of drilling that typically requires no water, drilling mud, or pressurized air as a circulating fluid. The auger is hollow on the inside to allow entry of a center rod, which holds a plug at the bottom of the auger or a sampling tool. The hollow opening allows downhole testing and sampling at the bottom of the boring without having the side walls cave in. The HSA method may be used in combination with mud rotary drilling to temporarily support (i.e., “case”) the borehole across loose materials. The HSA method may also be used to install piezometers at depth and for placing filter material around the piezometer as the HSA flights are backed out of the hole. The HSA method is expected to be used in the majority of areas where unconsolidated sediments are encountered. The use of the HSA method may be impeded when encountering dense uniform sand, large cobbles, and/or a high groundwater table and generally cannot be used to drill into rock. Other drilling methods described below will be used if the HSA method of drilling is not feasible. The support equipment for auger drilling would include a smaller vehicle to carry the HSA flights and other equipment/supplies to the geotechnical testing site and the field geotechnical engineer/geologist’s vehicle. 3.4.1.2 Mud Rotary Drilling Mud rotary drilling consists of rotating a smooth-walled hollow drill stem and advancing a variety of drill bits at the end of the drill stem. The materials are brought up from the borehole by pumped water (or mud slurry) typically travelling down through the drill stem, out the bit, and flowing up the outside of the drill stem. This method carries drill cuttings to the ground surface with the circulating water. A tub at the surface collects the drill cuttings and holds the water and cuttings (mud) for recirculation. If caving or water loss is encountered, the driller will use casing to stabilize the borehole. Mud rotary can be used to drill soil and rock using a tri-cone hardened steel bit. A special rock bit includes using diamond- or carbide-tipped coring barrels. The coring barrel allows cutting and retrieval of cylindrical rock samples (cores). Once a rock layer is encountered, the driller will attempt to retrieve a continuous core sample to the depth of the borehole. Mud rotary drilling is expected to be used in the majority of areas where rock is encountered within the depth of the borings. The equipment for mud rotary drilling includes the drill vehicle, a support vehicle for rods and equipment, a water-tank vehicle and the field geotechnical engineer/geologist’s vehicle. Mud rotary drilling requires a vehicle to supply water, which may have difficulty accessing geotechnical testing sites and thus limiting its use in some difficult access areas. Water used for mud rotary drilling will be obtained and tracked according to the conservation measures outlined in the Biological Assessment for the Project.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 21

Mud Rotary drilling will utilize a recirculation tank that captures unused or leftover mud. Any mud left in the recirculation tank will be pumped back into the water tanks and disposed of at a local landfill. Spilled mud will be shoveled, pumped or vacuumed (dependent on volume and consistency) into the water tanks and disposed of at the local landfill. Water bars will be installed to intercept and cause ponding of sediment laden runoff. 3.4.1.3 Air Rotary Drilling The air rotary drilling method is similar in principle to mud rotary drilling; however, this method uses compressed air as the circulating medium rather than water or mud slurry. Drill cuttings are retrieved from under a hood placed over the borehole. Because air rotary does not use water-based drilling fluids, clogging is less likely than with mud rotary drilling. A special type of air rotary drilling involves the use of an air hammer. Compressed air is pumped through the drill pipe to an air-hammer bit in the borehole. The pneumatic bit strikes the rock very rapidly. During drilling, the pipe string is rotated by the drilling vehicle to aid in keeping the borehole straight. The compressed air, escaping from the bottom of the air hammer, carries the pulverized cuttings to the surface. A water spray or mist will be applied to control dust at geotechnical investigation sites when necessary. The support equipment for air rotary drilling will include a support vehicle towing an air compressor and the field geotechnical engineer/geologist’s vehicle. The support equipment required may have difficulty accessing geotechnical testing sites, thus limiting its use in some difficult access areas. 3.4.1.4 Sonic Drilling Sonic drilling uses a rotating drill string as with other drilling methods; however, this method also uses a sonic drill head to impart a high frequency vibration on the drill stem and an open pipe casing/core barrel that is advanced into the subsurface materials. As the casing is advanced, soil and rock samples are forced up into the casing, providing a continuous sample of the subsurface soil and rock. The frequency of vibration can be changed to match the subsurface conditions, making this type of drilling generally faster than the other drilling methods. However, generally more expensive equipment is required when compared to HSA and mud rotary methods. The support equipment for sonic drilling would include a vehicle to carry the drill to geotechnical testing locations, a support vehicle to carry the drilling rods, and the field geotechnical engineer/geologist’s vehicle. 3.4.1.5 Down-Hole Air Hammer Drilling The down-hole air hammer drilling method uses tooling in which an outer drill casing is advanced along (more or less simultaneously, depending on the manufacturer) with the drill bit. The drill bit has a section that moves outward through eccentric action when the drill rods are rotated or expands by spring action, thereby making the borehole larger than the casing it passes through. The larger diameter hole allows the casing to follow along behind the bit by being hammered or pushed as the hole is drilled. The bit is typically a tungsten carbide button bit that is driven by a percussion hammer during rotation. A common brand name for this type of drilling is ODEX (overburden drilling with eccentric bit). There is also a concentric drilling system (without the eccentric bit), Symmetrix, which allows the casing to advance along with the bit. Drill cuttings are removed by compressed air travelling down the drill rod to the bit and returning via the annulus between the drill rod and casing and then lifting the cuttings to the surface. The air path can be reversed, which is called reverse circulation. Water can be added (from a water tank) or drilling can be done dry. The under-reamer drilling method is especially useful where hard bedrock or hard boulders are encountered. The support equipment for under-reamer drilling includes an air compressor (which some rigs have on board and some rigs tow behind), a support vehicle to carry the drill casing, and the field geotechnical engineer/geologist’s vehicle. 3.4.1.6 Cone Penetration Testing The Cone Penetration Test (CPT) is a testing method used to determine the engineering properties of soils and to delineate soil lithology. The test method consists of pushing an instrumented cone at a constant rate. The instruments measure tip (cone) resistance and friction resistance along the sides. The CPT delineates soil layers from the ratio of cone to side friction resistance. CPT drilling provides excellent geotechnical information in

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 22

softer formations but typically reaches refusal in soils with gravel, medium dense sands or hard fine grained soils. CPT probes do not collect soil samples and therefore rely on correlations to determine soil type. CPT cones are capable of performing seismic CPT testing at set intervals to determine shear wave velocity of the soils. CPT cones also read pore water pressures as they are advanced to determine depth of groundwater and if artesian groundwater conditions are encountered. CPT equipment could be used to advance other measurement tools. An example is the flat plate dilatometer, an approximate 4-inch-wide plate that is pushed into the ground to measure lateral pressures. Measurements from the dilatometer tool could be used for lateral response analysis of the tower foundations. The CPT drill is typically mounted in a box truck or on a track/all-terrain vehicle. The support equipment for CPT drilling includes a support truck for equipment, and the geologist/engineer vehicle. 3.4.2 Sampling Methods During drilling operations, samples will be obtained (except in the case of rock coring and CPT) every 2.5 feet for the first 10 feet below ground surface, then once every 5 feet or at each change in soil or rock type. For rock coring and CPT Soil sampling will be performed either using split-spoon samplers hammered into sandy soil; thin-walled Shelby tubes pushed into fine-grained soil (clays or silts); or grab samples taken from the drill “cuttings” (broken-up material). Once the soil sampler reaches a hard material (i.e., rock or rock-like) that cannot be sampled using the methods described above, the drilling and sampling equipment will be changed to continuous rock coring. These sampling methods are described in the following sections. 3.4.2.1 Grab Sampling Each of the drilling methods described above in Section 3.4 (except in the case of rock coring and CPT) will bring cuttings to the surface. At the discretion of the field geologist stationed at the drilling vehicle, a grab sample of the cuttings may be collected as they come out of the borehole to observe grain-size, moisture changes, or to confirm that other sampling methods are recovering adequate samples of material. Grab sampling is the least preferable sampling method because the sample interval is approximate and the material is mixed and very disturbed. 3.4.2.2 Thin-walled Tubes Relatively undisturbed samples of fine-grained and/or cohesive soils encountered in the borings will be taken by rapidly pushing a 3-inch-diameter (outside) thin-walled tube sampler (also known as Shelby tube sampler, American Society for Testing and Materials [ASTM] D1587) approximately 1.5 feet into the soil using the hydraulic down push from the drill vehicle. 3.4.2.3 Split-Spoon Sampling Samples of granular soils encountered in the borings will be taken by driving a 2-inch-diameter (outside) split-spoon sampler (ASTM D1586) 18 inches into the soil with a 140-pound hammer falling freely from a height of 30 inches. This method is also known as the Standard Penetration Test. Where gravelly soils are encountered, a larger diameter split spoon sampler (usually 3-inches in diameter) driven by a 300-pound hammer may be used to improve sampling recovery. 3.4.2.4 Coring Rock encountered in the borings will be continuously sampled to the termination depth of the boring using a core barrel fitted with a carbide or diamond bit. 3.4.3 Geophysical Surveys In addition to geotechnical drilling, less invasive ReMi geophysical surveys can be conducted in environmentally sensitive areas (e.g. sensitive plant or wildlife habitat areas, significant cultural resource areas); in remote areas that cannot be easily accessed by a drill vehicle; and in areas of highly erosive soils or fragile locations that are subject to puddling, compaction or extensive removal of protective ground cover resulting in long-term

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 23

disturbance. Results from ReMi surveys must be correlated to a nearby boring in order to provide reliable design parameters. ReMi surveys will be conducted to supplement rock condition information obtained through exploratory drilling. A ReMi survey may be conducted to obtain information on depth to bedrock, moduli of each layer detected, rock excavatability (rippability), and other design/construction considerations. In areas where higher noise levels can be tolerated, the ReMi equipment can be switched to refraction mode and a metal plate placed on the ground and struck with a sledge hammer to produce a high-frequency energy source. The maximum noise level may be generated by pounding a metal plate with a sledge hammer with an estimated noise level of 150 decibels at a 5-meter distance from the source. By comparison, small arms fire is about 170 decibels at a distance of approximately 1.5 feet. Equipment to be used in conducting the ReMi survey includes a multichannel seismograph, low- and high-frequency geophones laid out from 10-foot to 50-foot intervals. Ten-foot intervals between geophones with a 120-foot array will provide 30 to 40 feet of penetration and are anticipated to be sufficient. Geophones that are 3 inches long will be hand–pushed into the ground and removed after the readings are taken. In hard ground conditions, geophones can be placed directly on the ground surface. 3.5 Drill Vehicle Types The drilling methods and equipment (rigs) described above in Section 3.4.1 will be mounted on road legal trucks, tracked vehicles, or oversized-tire all-terrain vehicles (ATV). All the drilling vehicles, can be equipped with HSA, ODEX, sonic drills, and mud rotary/coring drilling systems. Platform rigs can be transported in pieces to a drill site via helicopter and would use only the mud rotary drilling method to advance the borehole. Additionally a man-portable drill rig may be used where access is not available. This rig type is transported in pieces as closely as possible to the borehole site using road-legal vehicles or off-highway vehicles. The pieces are packed into the site by personnel, ATV, or livestock and assembled on site to perform the drilling. The majority of the boreholes will be drilled using truck mounted drilling rigs; however, other drilling rigs may be used for areas where the truck-mounted drilling rigs cannot be used due to steep terrain and/or difficult access. Other vehicles and equipment will also be used to support geotechnical testing and may include a water truck or support vehicle, an air compressor, field geotechnical engineer/geologist’s pick-up truck or utility vehicle and possibly another support pickup truck. 3.5.1 Truck Mounted Truck-mounted drilling rigs are proposed for the majority of the borings. These rigs are road-legal, heavy trucks that require relatively flat access (5 percent grade or less). The rigs will travel on existing roadways and two-track trails as close as possible to geotechnical testing sites and then overland on firm ground. Truck-mounted drilling rigs are typically 30 feet long, 8.5 feet wide, and 12 feet high with mast down and 34 feet high with the mast up and have a gross vehicle weight of approximately 30,000 pounds with 30 to 50 pounds per square inch (psi) ground pressure. Cone Penetrating Testing (CPT) equipment could be truck-mounted, or carried by drilling rigs. CPT trucks are approximately 54,000 pounds with 30 to 50 psi ground pressure. Figure 3-7 shows a typical truck mounted drill vehicle. 3.5.2 All-Terrain Vehicles ATV rigs, also known as balloon-tired rigs, are an alternate drill vehicle type for borings where truck-mounted rigs cannot gain access, including areas with softer ground conditions and up to 20 percent grade. ATV rigs are typically 25 feet long, 8.5 feet wide, and 15 feet high with mast down and 25 feet high with mast up and have rubber balloon tires allowing low-ground-pressure and thus lower ground disturbance. ATV rigs are transported to the Project area on low-boy trailers using existing roadways and two-track trails as close as possible to geotechnical testing sites and then overland to the geotechnical testing sites. If the ground is firm enough, ATV rigs can travel faster overland than the tracked rigs discussed in the next section. Figure 3-8 shows a typical ATV mounted drill vehicle. 3.5.3 Tracked Vehicles

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 24

Track-mounted drilling rigs are another alternative drill vehicle type for borings where softer ground conditions exist with up to 20 percent grade. These rigs are approximately 8,000 pounds with rubber tracks, resulting in approximately 10 psi ground pressure, the lowest available ground disturbance mobile vehicle for softer ground. Tracked rigs are typically 22 feet long, 6 feet wide, and 22 feet high with mast up. Track rigs travel on low-boy trailers using existing roadways and two-track trails to get as close as possible to geotechnical testing sites and then overland to the geotechnical testing sites. Track rigs are driven by remote-control by an operator walking along the side of the vehicle as it is moving. Track-mounted drilling rigs could also be used to carry CPT equipment. Track-mounted CPT equipment is heavier, up to 25 tons, typically 27 feet long, 10 feet wide and 12 to 13 feet high. The weight of a CPT track-mounted vehicle is distributed using wide rubber tracks, resulting in 4 to 5 psi ground pressure. Figure 3-9 shows a typical track mounted drill vehicle. 3.5.4 Platform Rig and Helicopter A platform drilling vehicle may be used to access areas where the mobile drill rigs described above cannot access borehole sites. These rigs would be transported to the geotechnical exploration site by helicopter in eight to ten pieces and assembled onsite. Platform rigs are approximately 6,500 pounds assembled, are up to 32 feet high with mast up, have base dimensions of 8.5 feet by 6 feet, and have 5-foot long stabilizer bars extending out from all sides of the base. The use of a platform vehicle would require a staging area near existing roadways to load the helicopters with the unassembled platforms for transport to the exploration site. Figure 3-10 shows a typical platform mounted rig.

FIGURE 3-7 TYPICAL TRUCK MOUNTED DRILL VEHICLE

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 25

FIGURE 3-8 ATV MOUNTED DRILL VEHICLE

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 26

FIGURE 3-9 TRACK MOUNTED DRILL VEHICLE

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 27

FIGURE 3-10 PLATFORM MOUNTED DRILL RIG

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 28

4.0 GEOTECHNICAL EXPLORATION LOCATIONS 4.1 Introduction This section provides information regarding borehole locations, land ownership and jurisdiction, access requirements, key environmental resources, and potential seasonal restrictions. 4.2 Drilling Locations, Access, and Sensitive Resources for Route Links,

Substations and Series Compensation Stations 4.2.1 Wyoming 4.2.1.1 Description, Drilling Locations and Access Borehole locations in Wyoming are located along Links W15, W21, W35, W36, W30, W32, W101, W125, W108, W107, W116, W113, W302, and W411 for a total of 96 boreholes. The boreholes are located on BLM, state, City of Rawlins and private lands. There are a total of 49 boreholes located on BLM-Rawlins FO land, two on State of Wyoming land, one on City of Rawlins Land, and 44 on private land. Borehole ID #Aoelus DE through B-1C-188 in Wyoming are shown in Volume II, Map Set 1A and Map Set 2A of the NEPA POD. Drilling and exploration sites in Wyoming would be accessed from Medicine Bow Road/County Road 121 in the vicinity of Aeolus Substation and north of Hanna, US 30, Hanna Draw Road, Old Lincoln Highway, and Arch Road in the area of Hanna. In the Rawlins areas, access would occur from the I-80-U.S. 30 exit, C.R. 347, Twentymile Road and local roads paralleling the freeway on the north and south. West of Rawlings, I-80 exits 211,209, 206, 204, and 201 would be used for access to local and two-track roads. Primary access would occur from WY 789, Wamsutter Road, and South Barrel Springs Draw Road south of Wamsutter. North and west of Baggs, Cherokee Trail Road and two track roads would be used for access in Wyoming. Access to most of the boreholes (90 of 96) in Wyoming would be by various distances of overland travel. Refer to Appendix G-1 for anticipated access type to each borehole. 4.2.1.2 Sensitive Resources Avoidance and survey areas, avoidance dates, and survey requirements are detailed in Section 5.2 and Appendix B-1. Key wildlife and botanical features and environmentally sensitive areas within Wyoming are depicted on Map Sets 1A and 2A include:

• Greater Sage-grouse Core Area or Priority Habitat • Greater Sage-grouse Habitat within 4-miles of Leks • Greater Sage-grouse General Habitat • Black-footed ferret Management Areas • Potential Habitat for:

o White-tailed Prairie Dog o Pygmy Rabbit o Mountain Plover o Wyoming Pocket Gopher o Ute Ladies’-tresses

4.2.2 Colorado 4.2.2.1 Description, Drilling Locations and Access Borehole locations in Colorado are located along Links C31, C61, C71, C91, C94, C95, C175, C186, and C188 for a total of 44 boreholes. The boreholes are located on BLM managed, state and private lands. There are a total of 15 boreholes located on BLM-Little Snake FO land, 13 boreholes on BLM-White River FO land, seven on

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 29

state land, and nine on private land. Borehole ID # B-1C-199 through -218, B-2A-12 through -178.1, and B-2B-33 through -173 in Colorado are shown in Volume II, Map Set 1B and Map Set 2B of the NEPA POD. Drilling and exploration sites in Colorado would be accessed from existing gravel and two-track roads located off County Road 21/21N and County Road 4 near the border of Wyoming. Near Sunbeam, boreholes would be accessed from Colorado Highway 318, County Road 10, and adjacent existing gravel and two-track roads. South of Sunbeam, primary access would be from U.S. 40 and adjacent roads, County Road 85, and two-track roads used for existing transmission line access generally located to the south and east of U.S. 40. South of Dinosaur, primary access is from Colorado Highway 64 and County Road 21 going into Utah. Access to most of the boreholes (39 of 44) in Colorado would be by various distances of overland travel. Refer to Appendix G-1 for anticipated access type to each borehole. 4.2.2.2 Sensitive Resources Avoidance and survey areas, avoidance dates, and survey requirements are detailed in Section 5.2 and Appendix B-1. Key wildlife and botanical features and environmentally sensitive areas within Colorado are depicted on Map Sets 1B and 2B include:

• Greater Sage-grouse Core Area or Priority Habitat • Greater Sage-grouse Habitat within 4-miles of Leks • Greater Sage-grouse General Habitat • Black-footed ferret Management Areas • Colorado River Fish Designated Critical Habitat • Potential Habitat for:

o Yellow-billed Cuckoo o White-tailed Prairie Dog o Pygmy Rabbit o Mountain Plover o Ute Ladies’-tresses

4.2.3 Utah 4.2.3.1 Description, Drilling Locations and Access Borehole locations in Utah are located along Links U242, U280, U285, U300, U400, U401, U404, U413, U418, U408, U411, U417, U445, U504, U508, U514, U516, U560, U530, U533, U539, U460, U621, U625, U638, U639, U650, U644-345, U643-345, U640-345, and U642 for a total of 237 boreholes. The boreholes are located on BLM managed, USFS, state, BIA, City of Nephi and private lands. There are a total of 8 boreholes on BLM-Filmore FO land, one on BLM-Price FO land, four on Salt Lake FO land, 57 on Vernal FO land, four on Manti-La Sal National Forest land, 12 on Uinta-Wasatch-Cache National Forest land, 32 on state owned land (UDNR, school and institutional trust) 4 on Nephi City owned land, two on Bureau of Indian Affairs land, and a total of 112 located on private land. Borehole ID #B-2B-199 through -243, B-3A-1 through -185, B-3B-1 through -127, B-3X-21 through -148, B-3Y-1 through -101, B-3E-1 through Clover Substation DE, B-4C-1 through -15, 385, 397, 500 and 516 Utah are shown in Volume II, Map Set 1C and Map Set 2C of the NEPA POD. Drilling and exploration sites in Utah would be accessed from S. Bonanza Highway, Fiddler Road, Hatch Reservoir Road, East Coyote Wash Road, and adjacent gravel and two-track roads used for existing transmission line access. Primary access would also occur from South Glen Bench Road, Middle Road, Seep Ridge Road, Willow Creek Road, and Moon Bottom Road east of the Green River. West of the Green River, primary borehole access would be from Sand Wash Road, Four Mile Wash Road, West Pipeline Road, Pete’s Wash Road, North Horner Knoll Road, and other gravel and two-track roads, with overland access occurring for many boreholes located between Nine Mile Canyon Road and the Green River. West of Nine Mile Canyon Road, boreholes would be accessed from Five Mile Draw Road or Rye Patch Road, with overland access occurring for several exploration sites between Argyle Canyon Road and Rye Patch Road. Big Sulphur Canyon Road, Minnie Maud Road, and Whitmore Park Road would provide access east of Emma Park and U.S. 191. Emma Park Road, U.S.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 30

191, and U.S. 6 provides access to two-track roads and overland access in and around Soldier Summit. North of U.S. 6, existing transmission line access roads would serve as primary access routes to the boreholes between Soldier Summit and U.S. 89. Lake Fork Road, Blind Canyon Road, East Lake Canyon and other minor gravel and two-track roads would provide access from U.S. 89 to existing transmission line access roads and boreholes. State Highway 132 and N. Frontage Road would provide primary access to existing transmission line roads and boreholes east of Nephi via Red Canyon Road, Reese’s Flat Road and Footes Road within the Uinta National Forest. West of I-15, Spider Road, N. Main Street, N. Meadow Lane, Bird Farm Road, and N. Mona Road provide access to exiting transmission line roads and boreholes north of Nephi. Access to most of the boreholes (208 of 237) in Utah would be by various distances of overland travel. Refer to Appendix G-1 for anticipated access type to each borehole. 4.2.3.2 Sensitive Resources Avoidance and survey areas, avoidance dates, and survey requirements are detailed in Section 5.2 and Appendix B-1. Key wildlife and botanical features and environmentally sensitive areas within Utah are depicted on Map Sets 1C and 2C include:

• Greater Sage-grouse Core Area or Priority Habitat • Greater Sage-grouse Habitat within 4-miles of Leks • Black-footed ferret Management Areas • Colorado River Fish Designated Critical Habitat • Potential Habitat for:

o Yellow-billed Cuckoo o Mexican Spotted Owl o White-tailed Prairie Dog o Pygmy Rabbit o Mountain Plover o Ute Ladies’-tresses o Clay Phacelia o Clay Reed Mustard o Desert Milkvetch o Shrubby Reed-mustard o Uinta Basin hookless cactus

4.2.4 Substations and Series Compensation Sites 4.2.4.1 Clover Substation Clover Substation is located on the south terminus of the Project on private land. Boreholes B-4C-5 through -8 are located directly adjacent to or within the fence line of the existing station. Clover Substation and vicinity is shown on Map Set 1C, Panel 74, and Map Set 2C, Panel 754. Access to the borehole and substation would occur from W2700N Street/West Meadow Lane and Bird Farm Road on the south and existing transmission line access roads, or West Cow Lane and existing transmission line access roads from the north. No overland access would occur for boreholes associated with Clover Substation. Avoidance and survey areas, avoidance dates, and survey requirements associated with access and geotechnical exploration in the vicinity of Clover Substation are detailed in Appendix B-1. Existing access will be used, and associated boreholes are located in areas of previous disturbance associated with the substation. 4.2.4.2 Series Compensation Sites

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 31

There are currently no SCS site specific boreholes or geotechnical exploration sites associated with the Geotechnical Exploration Plan (see Appendix G-1). Geotechnical investigation areas for SCS sites are currently captured at borehole locations identified along the Project centerline within SCS Siting Areas shown in Volume II of the NEPA POD. When specific SCS sites are identified, additional geotechnical investigations may be necessary. 5.0 CONSTRUCTION PERMITS AND CLEARANCE SURVEYS 5.1 Anticipated Drilling Related Permits Federal, state and local permits or approvals required for the project are detailed in Section 1.6 of the NEPA POD. For drilling and exploration activities, it is anticipated that drilling would potentially require encroachment permit for drilling should it occur within a country highway or roadway corridor. As part of the geotechnical investigation program implementation strategy, PacifiCorp would avoid sensitive features that would require environmental permitting for geotechnical activities (see Section 5.3). 5.2 Environmental Clearance Surveys and Seasonal Restrictions Environmental resource clearance surveys will be conducted in areas planned for geotechnical investigation exploration and drilling activities. The purpose of the environmental resource clearance surveys is to determine the presence or absence of sensitive resources relative to the location of geotechnical exploration and drilling activities and access. Surveys will be conducted in accordance with the Resource Survey Protocols detailed in Appendix B-1 (Biological Resources Survey Plan) of the NEPA POD, and must be accepted or recommended by the affected federal land management agency, United States Fish and Wildlife Service (FWS), and/or state wildlife agencies. A list of special status plant and wildlife for which surveys must be conducted, the need for pre-survey habitat assessments, the applicable agency-approved survey methodologies and the temporal and spatial extent of each survey for the geotechnical investigation are include in Appendix B1, Attachment A, Table 1 – Biological Survey Requirements for Geotechnical Investigation. If protected or managed species are identified during surveys, appropriate action will be taken to avoid adverse impacts on the species and its habitat, which may include altering the placement of boreholes or overland travel routes, or modifying the location of geotechnical activity as described below. Appropriate action taken will be determined in coordination with the BLM, USFS, FWS and other appropriate resource agencies. Biological surveys are anticipated to occur beginning in 2016, and will be performed prior to any ground disturbing activities. See Appendix G-2 for a general drilling schedule. PacifiCorp has developed a geotechnical investigation program implementation strategy that will result in minimal or no impact to sensitive resources. Based on the environmental resource clearance surveys, if presence of a sensitive resource is identified, the following methods will be implemented, in the order listed and as approved by the land management agency prior to initiating geotechnical exploration activities:

1. Monitor borehole during drilling activities for the presence of sensitive features; 2. Adjust drilling date outside seasonal restrictions; 3. Use alternative access or drilling type; 4. Relocate borehole or exploration activity to a different location; and

Abandon borehole or exploration activity in the area

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 32

Appendix B1 of the NEPA POD describes the environmental resource clearance surveys that will be conducted, the survey methodologies to be utilized, the anticipated schedule of the environmental resource clearance surveys, and the seasonal or spatial restrictions for applicable sensitive resources. Surveys are anticipated to begin in spring 2016. Seasonal restrictions potentially associated with geotechnical exploration sites include:

• Mule Deer Crucial Winter Habitat (December 1-April 30) • Mule Deer Summer Habitat (April 15-July 1; Salt Lake City BLM FO) • Elk Crucial Winter Habitat (December 1-April 30) • Pronghorn Crucial Winter Habitat (December 1-April 30; White River BLM Field Office) • Raptor Seasonal Restrictions

6.0 GEOTECHNICAL INVESTIGATION SPECIFIC ENVIRONMENTAL

PROTECTION MEASURES 6.1 Introduction Environmental Protection Measures specific to the implementation of the geotechnical investigation program will be implemented to avoid, reduce or minimize potential environmental impact are described in the following sections. As applicable, design features and selective mitigation measures identified in the NEPA POD that will apply to the geotechnical investigation program are identified in NEPA POD Table 4-1 and 4-2 and are summarized below. Where appropriate, Design Features of the Project for Environmental Protection and mitigation measure text has been modified to address geotechnical exploration activities rather than just transmission line construction, operation and maintenance. 6.2 Design Features of the Project for Environmental Protection Project Design Features for Environmental Protection will be implemented to reduce potential geotechnical exploration impacts as detailed in Table 4-1 in Section 4-Environmental Setting, Issues and Mitigation Measures of the NEPA POD. Applicable Project Design Features for Environmental Protection include:

1. In geotechnical borehole locations, vegetation will be left in place wherever possible, and original contour will be maintained to avoid excessive root damage and allow for resprouting in accordance with the reclamation plan.

2. In exploration work areas and overland access route where there is ground disturbance, surface reclamation will occur as required by the landowner or land-management agency. The method of reclamation normally will consist of, but not be limited to, returning disturbed areas to their natural contour, reseeding, installing cross drains for erosion control, placing water bars in the road, and filling ditches.

All areas on lands administered by federal agencies disturbed during geotechnical exploration will be seeded with a seed mix appropriate for those areas. The federal land-management agency will approve a seed mix that fits each range type. Seeding methods typically will include drill seeding, where practicable; however, the federal land-management agency may recommend broadcast seeding as an alternative method in some cases.

A Reclamation, Revegetation, and Monitoring Framework Plan identifying reclamation stipulations (e.g., topsoil stripping and storage, alleviation of soil compaction in construction areas, timing of reclamation activities, species lists, monitoring methods, standards for reclamation success, bond-release criteria, etc.) will be developed and

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 33

incorporated into the NEPA POD, which will be approved by the affected federal land-management agency prior to the issuance of a right-of-way grant (BLM), special-use authorization (USFS), and encroachment permit and grant of easement (BIA), etc.

3. Special Status Species, threatened and endangered species, or other species of particular concern will be considered in accordance with management policies set forth by appropriate land-management or wildlife-management. This will entail conducting surveys for plant and wildlife species of concern areas along the Project as agreed on by the agencies. Survey protocols must be accepted or recommended by the affected federal land-management agency, FWS, and state wildlife agencies, as appropriate. In cases for which such species are identified, appropriate action will be taken to avoid adverse impacts on the species and its habitat, which may include altering the placement of roads, boreholes or exploration sites, where practicable, as approved by the landowner, as well as monitoring activities.

5. To prevent the spread of noxious weeds, a Noxious Weed Management Plan will be developed and incorporated into the POD, which will be approved by the affected federal land-management agencies prior to the issuance of the BLM, USFS, and BIA Records of Decision; a right-of-way grant (BLM) or special-use authorization (USFS), or encroachment permit and grant of easement (BIA). This plan will be based on the principles and procedures outlined in the BLM Integrated Weed Management Manual 9015 and Forest Service Noxious Weed Management Manual 2080. On private land, the Plan will be approved by a county weed-management officer.

6. Avoid geotechnical investigation, vegetation clearing and other activities when possible during the migratory bird nesting season, between February 1 and August 31; however, dates may vary depending on species, current environmental conditions, results of preconstruction surveys, and approval by agency biologists or agency-approved environmental inspectors in coordination with agency biologists.

7. If geotechnical investigations, vegetation clearing or other activities could not be avoided during the migratory bird nesting season (between February 1 and August 31), migratory bird and nest surveys will be required within 7 days of any ground-disturbing activities. A spatial nest buffer will be placed around each active nest detected during the surveys until such time as the nest is determined through monitoring to be no longer occupied. Appropriate spatial nest buffers (by species or guild) and nest monitoring requirements will be identified using the best available scientific information through coordination with the FWS and other appropriate agencies and will be provided in a nest management plan incorporated into the POD.

8. Agency guidelines for raptor protection during the breeding season will be followed as detailed in Appendix B1of the NEPA POD.

10. In consultation with appropriate land-management agencies and the State Historic Preservation Officers and in accordance with the Programmatic Agreement (to comply with Section 106 of the National Historic Preservation Act) entered into among the BLM; U.S. Forest Service (USFS); Bureau of Indian Affairs; the states of Wyoming, Colorado, and Utah; consulting parties; and tribes, specific mitigation measures for cultural resources will be developed and implemented to mitigate any identified adverse impacts. These may include Project modifications to avoid adverse impacts to cultural

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 34

resources, monitoring of construction activities, and data recovery studies.

14. A Fire Protection Plan will be developed and incorporated into the POD, which will be approved by the BLM, USFS and BIA prior to the issuance of a right-of-way grant (BLM), special-use authorization (USFS), and encroachment permit and grant of easement (BIA).

All internal and external combustion engines on federally managed lands will be operated per 36 CFR 261.52, which requires all such engines to be equipped with a qualified spark arrester that is maintained and not modified.

16. During and after geotechnical investigations, the right-of-way will be free of non-biodegradable debris. Slash will be left in place or disposed of in accordance with requirements of the land-management agency or landowner.

17. In disturbed geotechnical borehole sites and temporary work areas, the topsoil will be salvaged/segregated and distributed and contoured evenly over the surface of the disturbed area after construction completion. The soil surface will be seeded with an agency-approved seed mix and left rough to help reduce the potential for weeds and erosion.

18. Grading will not occur for geotechnical exploration; geotechnical exploration sites will be accessed by driving overland in areas approved in advance by the land-management agency in predesignated work areas.

19. In consultation with appropriate land-management agencies, specific mitigation measures for and/or treatment of paleontological resources will be developed and implemented to mitigate any identified adverse impacts. These measures will include:

• preparation of a Paleontological Resources Treatment Plan;

• paleontological surveys;

• education of construction personnel;

• monitoring ground disturbance;

• deposition in a paleontological repository; and

• curation.

22. Fences, gates, and walls will be replaced, repaired, or reclaimed to their original condition or to current specifications as required by the landowner or the land-management agency in the event they are removed, damaged, or destroyed by construction activities. Fences will be braced before cutting. Temporary gates or enclosures will be installed only with the permission of the landowner or the land-management agency and will be removed/reclaimed following construction.

Calving, lambing, and trailing areas will be avoided in the Project right-of-way and ancillary facilities. Calving season generally occurs between December and February but may vary from region to region. Lambing season generally occurs between March and June. Trailing areas (areas where livestock producers move livestock across lands

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 35

to facilitate proper grazing management) can occur throughout the Project area and timing may vary throughout the year. Prior to construction, the Company will coordinate with the applicable land-management agency or private landowner to avoid areas used for calving, lambing, and trailing during construction.

23. In cultivated agricultural areas, soil compacted by geotechnical investigations will be decompacted. Geotechnical exploration activities will occur as practical to minimize impacts on agricultural operations.

24. Where work will occur on hazardous and contaminated sites, the Company must seek approval from the U.S. Environmental Protection Agency. Work on contaminated sites must avoid remedial structures and workers must use adequate worker protection measures for working in contaminated areas.

26. All vehicle movement outside of the right-of-way will be restricted to predesignated access, contractor-acquired access, public roads, or overland travel approved in advance by the applicable land-management agency, unless authorized by the CIC.

27. The spatial limits of geotechnical investigations, including vehicle movement, will be predetermined with activity restricted to and confined within those limits. No paint or permanent discoloring agents indicating survey or construction limits will be applied to rocks, vegetation, structures, fences, etc.

28. Prior to geotechnical investigations, all personnel will be instructed on the protection of cultural, paleontological, ecological, and other natural resources such as (a) federal and state laws regarding antiquities, paleontological resources, and plants and wildlife, including collection and removal; (b) the importance of these resources; (c) the purpose and necessity of protecting them; and (d) reporting and procedures for stop work.

29. All requirements of those entities having jurisdiction over air-quality matters will be adhered to. Any necessary dust-control plans will be developed and permits for construction activities will be obtained. Open burning of construction trash will not be allowed unless permitted by the appropriate authorities.

30. Hazardous material will not be discharged onto the ground or into streams or drainage areas. Enclosed containment will be provided for all waste. All waste produced (i.e., trash and litter, garbage, other solid waste, petroleum products, and other potentially hazardous materials) will be immediately removed to a disposal facility authorized to accept such materials. A Spill Pollution Prevention, Containment, and Countermeasures Plan Framework, will be developed as part of the POD.

Refueling and storing potentially hazardous materials will not occur within a 328-foot (100-meter) radius of a body of water in Utah and Colorado (500-foot [153-meter] radius in Wyoming), a 200-foot radius of all identified private water wells, and a 400-foot radius of all identified municipal or community water wells. Spill prevention and containment measures will be incorporated as needed.

32. Watering facilities (tanks, natural springs and/or developed springs, water lines, wells, etc.) will be repaired or replaced if they are damaged or destroyed by geotechnical investigations to their pre-disturbed condition as required by the landowner or land-management agency. Should geotechnical investigation activities prevent use of a

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 36

watering facility while livestock are grazing in that area, then the Company will provide alternate sources of water and/or alternate sources of forage where water is available.

33. Consistent with BLM Riparian Management Policy, surface-disturbing activities within 328 feet (100 meters) of a riparian areas (defined as areas of land directly influenced by permanent surface or subsurface water having visible vegetation or physical characteristics reflective of permanent water influence, including wetlands, stream banks, and shores of ponds or lakes) in Utah and Colorado will be required to meet exception criteria defined by the BLM, such as acceptable measures to protect riparian resources and habitats by avoiding or minimizing stormwater runoff, sedimentation, and disturbance of riparian vegetation, habitats, and wildlife species. In Wyoming, surface-disturbing activities within 500 feet (153 meters) of all perennial waters and/or wetland and riparian areas and 100 feet (30 meters) of all ephemeral channels will also be required to meet exception criteria in association with the BLM Rawlins Field Office RMP (BLM 2008b). Mitigation measures will be developed on a site-specific basis, in consultation with the affected federal land-management agency, and incorporated into the final POD.

If any disturbance was anticipated within 20 feet of the edge of a riparian area or other wetland habitat, a silt fence or certified weed-free wattle will be installed along the travel route on the wetland side unless the wetland is up-gradient.

34. Interagency-developed methods of avoidance, inspection, and sanitization as described in the Operational Guidelines for Aquatic Invasive Species Prevention and Equipment Cleaning (USFS 2009a) will be adhered to. If control of fugitive dust near sensitive water bodies is necessary, water will be obtained from treated municipal sources or drafted from sources known to contain no aquatic invasive species. Support vehicles, drill rigs, water trucks and drafting equipment will be inspected and sanitized, as necessary, following interagency-approved operational guidelines.

35. State standards for abandoning drill holes will be adhered to where groundwater is encountered.

36. Crossings of dry washes will be made during dry conditions, when possible. Repeated crossings will be limited to the extent possible but made at the same locations, if possible.

37. If a riparian crossing were required during wet periods with saturated soil conditions, vehicles will not be allowed to travel when soils are moist enough for deep rutting (4 or more inches deep) to occur unless prefabricated equipment pads were installed over the saturated areas or other measures were implemented to prevent rutting. Equipment with low-ground-pressure tires, wide tracks, or balloon tires will be used when possible.

38. Canal and/or ditch crossings will require placement of temporary bridges or improvement of existing crossings.

39. To minimize vehicle collisions with wildlife or livestock, a speed limit of 15 miles per hour will be employed on overland access routes.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 37

6.3 Selective Mitigation Measures Selective mitigation measures will be implemented to reduce potential geotechnical exploration impacts as detailed in Table 4-2 in Section 4 – Environmental Setting, Issues, and Mitigation Measures of the NEPA POD. Selective mitigation measures by Link Number are detailed in Table 4-3 of the NEPA POD (see Appendix G-1 for Link Numbers associated with geotechnical exploration locations). Also, Map Set 2 in Volume II of the NEPA POD illustrates geographical locations of selective mitigation measures detailed below. Applicable selective mitigation measures include:

2. Sensitive Resource Avoidance

No blading of new access roads will occur for geotechnical exploration or in proximity to certain sensitive resources during Project geotechnical investigations, construction or maintenance. Existing crossings and/or overland access routes will be used to access exploration areas. Methods such as “matting” could be used to stabilize access to work areas in sensitive areas, or new exploration areas will be identified. To minimize ground disturbance, overland routes must be flagged with easily seen markers, and the route must be approved in advance.

This selective mitigation measure will be applied in the following areas:

• Within 328-feet (100-meters) (Utah and Colorado) or 500 –feet (153-meters) (Wyoming) of streams, wetlands, water, and riparian vegetation communities

• Occupied habitat for federally listed threatened, endangered proposed threatened, or petitioned plant species including level 1 and Level 2 Scerocactus core habitat

• Designated critical habitat for Colorado River fish species (bonytail, Colorado pikeminnow, humpback chub, and razorback sucker)

• Occupied least chub habitat

• Occupied nesting habitat for southern willow flycatcher, Mexican spotted owl, and yellow-billed cuckoo

• Occupied pygmy habitat

• Occupied boreal toad habitat

• Where flat terrain and vegetation allow for cross-country access to avoid crossing riparian corridors

• In other locations, where required to comply with law, regulation, or BLM or other agency policy based on the results of preconstruction/pre-drilling resource surveys

7. Avoid Sensitive Features

Geotechnical exploration activities will be located so as to avoid sensitive features, including, but not limited to, wetlands, riparian areas, water courses, hazardous substance remediation, and cultural sites. The location where avoidance will occur would be determined in coordination with the agencies after reviewing the results of the resource surveys.

This selective mitigation measure will be applied in the following areas:

• On soils moderately susceptible to accelerated wind or water erosion (access levels 2, 5, and 6) or highly susceptible to accelerated wind or water erosion

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 38

(access levels 2, 3, 4, 5, and 6) and on Prime or Unique Farmland (access levels 2, 3, 4, 5, and 6). Access levels are defined in Section A3.3.3, Table A3-2 of the NEPA POD.

• Active mines and producing oil and gas or geothermal wells

• Permitted mines, coal leases, oil and gas leases, geothermal leases, and active mining claims

• Occupied habitat for federally listed threatened, endangered, proposed threatened, or petitioned plant species including Level 1 and Level 2 Sclerocactus core habitat Wetland, water, and riparian vegetation communities

• Occupied nesting habitat for southwestern willow flycatcher, yellow-billed cuckoo, and Mexican spotted owl

• Designated critical habitat for Colorado River fish species (bonytail, Colorado pikeminnow, humpback chub, and razorback sucker) and least chub

• Occupied white-tailed prairie dog colonies

• In other locations, where required to comply with law, regulation, or BLM or other agency policy based on the results of preconstruction biological resource surveys.

• Where land uses including residences, commercial buildings, oil/gas well pads, cemeteries, flood control facilities, pipelines, wastewater treatment plants and communication facilities could be avoided

• Where existing utilities and center-pivot irrigated fields could be avoided

12. Seasonal and Spatial Plant and Wildlife Restrictions

To minimize disturbance to identified plant and wildlife species during sensitive periods, geotechnical exploration activities will be restricted in designated areas unless exceptions are granted by the respective federal land-management agencies’ Authorized Officer or their designated representatives and other applicable regulatory agencies. A list of seasonal wildlife restrictions are presented in Appendix B1, Attachment 5 of the NEPA POD.

This selective mitigation measure will apply to the following areas (refer to Appendix B1, Attachment 5 – Seasonal Restrictions for Biological Resources):

• Level 1 Sclerocactus core areas

• Bighorn sheep crucial seasonal habitats and lambing areas

• Elk crucial seasonal habitats, migration corridors, and calving grounds

• Moose crucial seasonal habitats and calving grounds

• Mule deer crucial seasonal habitats, migration corridors, and fawning areas

• Pronghorn crucial seasonal habitats, migration corridors, and fawning areas

• Occupied nesting habitat for southwestern willow flycatcher, Mexican spotted owl, yellow-billed cuckoo, and mountain plover

• Greater sage-grouse core areas, priority habitat, general habitat, transmission line corridors designated in Wyoming Executive Order 2011-5, and habitat within 4 miles of leks inside and outside core areas or priority habitat

• In proximity to active raptor nests and winter roosts

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 39

• In other locations, where required to comply with law, regulation, or BLM or other agency policy based on the results of preconstruction biological resource surveys.

15. Limit Accessibility in Sensitive Habitats

Where feasible, access roads that traverse sensitive habitats will be gated or otherwise blocked in cooperation with the appropriate land-management agencies to limit public access. This selective mitigation measure will be applied to the following areas:

• Bighorn sheep crucial seasonal habitats and lambing areas

• Elk crucial seasonal habitats, migration corridors, and calving grounds

• Moose crucial seasonal habitats and calving grounds

• Mule deer crucial seasonal; habitats, migration corridors, and fawning areas

• Pronghorn crucial seasonal; habitats, migration corridors, and fawning areas

• Occupied black-footed ferret habitat

• Areas in proximity to active raptor nests and winter roosts

• Occupied habitat for federally listed threatened, endangered proposed listed, or petitioned plant species

• In other locations, where required to comply with law, regulation, or BLM or other agency policy based on the results of preconstruction biological resource surveys

6.4 Additional Environmental Protection Measures Additional environmental protection measures will be implemented to reduce potential geotechnical exploration impacts not addressed by design features or selective mitigation measures. Additional environmental protection measures include:

General

G-1 - All personnel involved in the geotechnical investigation activities will receive environmental training prior to commencing work. Training will emphasize compliance with all environmental laws, mitigation measures, environmental protection measures, and any other environmental stipulations as required by the BLM right-of-way grant, USFS special use permit, and BIA encroachment permit and grant of easement. Project-specific requirements and local issues will be addressed as necessary. A master list of all personnel that have completed training will be maintained. Hard hat stickers demonstrating attendance will be issued to attendees.

G-2 - No grading and/or road construction will be permitted in order to complete geotechnical investigation activities.

Erosion Control and Soil Resource Protection

EC-1 - All borings will be backfilled with the soil removed during drilling to minimize settlement and the amount of displaced soil. No open holes will be left unattended, and all borings will be fully backfilled before moving to the next boring. Geotechnical investigations will be conducted on as flat a surface as possible to minimize runoff velocity and erosion potential.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 40

EC-2 - In the temporary boring work area, the soil from the boring will be stockpiled and distributed and contoured evenly over the surface of the disturbed area after completion of the boring. The soil surface will be left rough and covered with surface litter, when possible to minimize the potential for wind erosion.

EC-3 - In areas where soil is disturbed, surface reclamation will normally consist of returning disturbed areas back to rounded contours and surface roughening (scarifying). Surface roughening is a method of erosion control that consists of mechanically creating an irregular surface on areas that have been disturbed. EC-4 - In locations where concentrated runoff is expected from mud rotary drilling, water bars will be installed to intercept and cause ponding of sediment laden runoff.

Spill Prevention, Containment, and Countermeasures/Waste (Hazardous and Solid)

SPCC-1 - Drill rigs shall be inspected for hydraulic leaks prior to mobilization. Spill kits must include absorbent pads for hydraulic leaks.

SPCC-2 - Vehicle refueling and servicing activities will be performed in approved areas located more

than 328 feet (100meters) (Colorado/Utah) or 500-feet (Wyoming) from wetlands and streams. Spill prevention and containment measures or practices will be incorporated as needed.

SPCC-3 - Spills will be promptly cleaned up and contaminated materials hauled to a disposal site that meets local jurisdictional requirements and in a manner consistent with federal and reporting and mitigation requirements. Appropriate land management agencies will be notified of any incidents on federal land.

SPCC-4 - If an upland spill occurs, berms will be constructed with available equipment to physically

contain the spill. Absorbent materials will be applied to the spill area. Containment materials will be excavated and temporarily placed on and covered by plastic sheeting in a containment area a minimum of 328 feet (100 meters) away from any wetland or water body, until proper disposal is arranged. Such spills will be reported immediately to the BLM and/or appropriate land manager/landowner as specified in Appendix C-3 of the NEPA POD.

SPCC-5 - If a spill occurs that is beyond the scope of on-site equipment and personnel, an Emergency Response Contractor will be identified to contain and clean-up the spill.

SPCC-6 - For spills in standing water, floating booms, skimmer pumps and holding tanks will be used as appropriate to recover and contain released materials on the surface of the water.

SPCC-7 - If pre-existing contamination is encountered during drilling, work will be suspended in the

area of suspected contamination until the type and extent of the contamination is determined. The type and extent of contamination; the responsible party; local, state, and federal regulations will determine the appropriate clean-up method(s) for these areas.

SPCC-8 - Refueling and storing potentially hazardous materials will not occur within a 328-foot radius (Colorado/Utah) or 500-foot radius (Wyoming) of a water body, all identified private water wells, and all identified municipal or community water wells.

SPCC-9 - All garbage or solid waste will be transported and disposed of properly at an approved disposal facility.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 41

Dust Control and Air Quality AQ-1 - All drilling equipment will be required to have and use appropriate emission control devices as required by federal and state regulations. AQ-2 - Excessive exhaust emissions from vehicles and drilling equipment will be prevented by proper

maintenance. AQ-3 - No open burning of trash, vegetation or other open fires will be allowed.

DC-1 - A water spray or mist will be applied to control dust at geotechnical investigation sites when necessary. Water will be procured from municipal sources and/or from landowners. All procured water will require written landowner approval, which will include how much water will be used as well as a map and shapefile showing the location of the procurement site. The appropriate land management agency will approve the application of any substances other than water for dust control and abatement. The use and source of all water used for geotechnical activities shall be recorded in accordance with the conservation measures outlined in the Biological Assessment for the Project. The implementation of a tracking tool will be required to track the use and source of all water used during all construction activities as a condition of the Section 7 consultation for water use in the Platt River and Colorado River basins. Re-initiation of consultation with FWS will be required if water use exceeds amounts consulted on by 10 percent.

Noxious Weed Control

NW-1 - All drilling equipment will avoid driving, drilling, or parking in areas with delineated noxious weed populations.

NW-2 - All drilling equipment and vehicles, including the undercarriages, will be power washed before and after traveling on overland access routes to geotechnical testing locations with delineated noxious weed populations.

Water Resources Protection WR-1 Several environmental protection measures will be implemented to minimize the potential effects on water resources. These protection measures include implementing the erosion control measures, restricting geotechnical investigation to designated access routes, minimizing clearing and disturbance of native vegetation, implementing reclamation and stabilization measures for disturbed areas, avoidance of sensitive features ( waterways, springs) , prohibiting refueling of vehicles outside designated staging areas, and implementing spill prevention and containment measures.

WR-2 Drilling will not be allowed in riparian areas or other wetland habitats. Access through riparian areas and other wetland habitats would be avoided by either driving around them or using an existing crossing.

WR-3 No jurisdictional wetlands or waters of the United States as defined by the U.S. Army Corps of Engineers will be impacted during geotechnical activities.

Health, Safety and Fire Protection

HSF-1 - Fire suppression actions in any geotechnical investigation work areas will be initiated to prevent fire spread on or to federally administered lands. If fire ignitions cannot be prevented or contained immediately, or if it is foreseeable to exceed the immediate capability of workers, the

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 42

operation will be modified or discontinued. No risk of ignition or re-ignition will remain when crews leave the geotechnical testing location.

HSF-2 - The appropriate Interagency Fire Center (IFC) will be notified immediately of the

location and status of any escaped fire:

• Applicable Interagency Fire Centers and phone numbers are specified in Appendix B9 – Fire Protection Plan.

HSF-3 - Prior to any operation involving potential sources of fire ignition from vehicles, equipment, or other means, fire danger ratings and red flag warnings will be reviewed.

• Fire Danger Ratings will be used to direct the daily activities and in field crew safety briefings. Fire Danger Ratings take into account current and antecedent weather, fuel types, and both live and dead fuel moisture, and will be used by the land-management agency in determining mitigation or curtailment of operations. Fire Danger Ratings and their descriptions are available on the Wildland Fire Assessment website at: http://www.wfas.net/index.php/fire-danger-rating-fire-potential--danger-32.

• The Red Flag Warnings are posted on http://www.wrh.noaa.gov/firewx/main.php.

Prevention measures to be taken each work day will be included in the onsite briefing of personnel supporting the geotechnical investigation activities. Consideration for additional mitigation or discontinuing the operation must be given in periods of extreme wind and dryness.

HSF-4 - Welding, grinding, or cutting activities will be conducted in areas cleared of vegetation within the range of the sparks that may occur with a particular action or activity. A spotter is required to watch for ignitions.

HSF-5 - Campfires or uncontained fires of any kind are prohibited.

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 43

ATTACHMENT G-1 SUMMARY GEOTECHNICAL EXPLORATION PLAN

HLY 037-862 (PER 02 01) 124186 (01/27/2016) DG PAGE 44

ATTACHMENT G-2 PRELIMINARY GEOTECHNICAL EXPLORATION SCHEDULE The preliminary geotechnical exploration schedule shows the general sequence of activities. Drilling is anticipated to begin in the 2nd quarter of 2016 and continue through the middle of the 4th quarter of 2017. The geotechnical exploration schedule is dependent primarily on environmental clearance survey completion, location and extent of required surveys, and the availability and number of drilling contractors that will be available during the scheduled drilling timeframes. Prior to geotechnical exploration and as required by the agencies, field surveys will be completed for special-status plants and wildlife, cultural resources and paleontological resources, and wetlands.

HLY

037

-862

(PER

02

01) 1

2418

6 (0

1/27

/201

6) D

G

PAG

E 45

No

tes:

#1 –

Drilli

ng/ex

plora

tion t

o beg

in aft

er su

rveys

with

in the

timefr

ames

spec

ified f

or ea

ch sp

ecies

in ac

cord

ance

with

the a

pplic

able

Envir

onme

ntal P

rotec

tion P

lans l

ocate

d in A

ppen

dix B

of th

e NEP

A PO

D.

#2 –

Drilli

ng m

ay oc

cur b

eyon

d the

begin

ning o

f Q4 2

016/1

7 dep

endin

g on s

easo

nal v

ariab

les su

ch as

rain/

snow

that

affec

t acc

essib

ility.