00017429 Exploration Drill Plan.pdf

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ODOT Geology/Geotechnical

EXPLORATION PLAN & INFORMATION FORM

GENERAL INFORMATION

Project Name: I-5 MP 1.6: Wildlife Crossing (K23100) Highway & Mile Point: I-5 (Pacific Hwy, #001), MP 1.6 County: Jackson EA No.: PE003436/001/J13 Project Description: Conduct a subsurface investigation to characterize soil, groundwater, and bedrock conditions for design and construction of the proposed I-5 Wildlife Overcrossing. The investigation will provide geotechnical information for the continuous buried wildlife crossing structure foundations.

Key No.: 23100 Subsurface Investigation For: Continuous wildlife overcrossing foundation system consisting of four (4) foundation footprints (northbound and southbound structures).

No. of Drill Holes: Advance twenty (20) borings distributed across the proposed overcrossing foundation footprints at approximately 100-foot spacing. Planned boring depth is approximately 50 feet, with an estimated total footage of approximately 1,000 feet consisting of about 500 feet of hollow-stem auger drilling and 500 feet of HQ3 wireline coring.

Anticipated Drill Hole Depths: 50 feet Other Investigation Methods: N/A GDM Recommendations: The exploration program was developed in accordance with the

ODOT Geotechnical Design Manual (2024), Chapter 4 – Field Investigations. Exploration locations and depths were selected to characterize the anticipated variability beneath the proposed wildlife overcrossing foundations. Final boring depths may be modified by the ODOT Project Geologist based on field conditions.

Anticipated Start Date: August / September 2026 Anticipated # Days to Drill 15-20 Erosion Control Required No Utility Location Required: Utility coordination by Geologist R/W, Staging Area, Site Access: None, drilling in roadway prism Environmental Clearances: TBD Traffic Control Plan: Shoulder closures and intermittent single-lane closures will be required to safely access drill locations within the highway median and shoulders. Traffic control will be provided by ODOT.

Mobility Notification: Yes

DRILLING INFORMATION:

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Drilling On Highway/Off Road: On highway, near shoulder and in ditch lines (see drill hole location map)

Anticipated Subsurface Material: Based on the 2023 exploration completed approximately 500 feet north of the proposed crossing, subsurface conditions are expected to consist of a thin section of roadway pavement (AC and/or concrete) and embankment fill over weathered volcaniclastic bedrock. Fill beneath the proposed crossing is anticipated to be significantly thinner than encountered previously because the earlier borings were located at the northern end of the cut section where fill/embankment should have been deeper. Bedrock is generally expected within about 5 to 10 feet of existing grade, although local variations should be anticipated. Expected lithologies include lapilli tuff, tuff breccia, brecciated tuff, volcaniclastic conglomerate, and localized basalt flows or intrusive bodies. Rock weathering and quality are expected to vary significantly from completely weathered (R0) to fresh rock (R5), with localized clay-altered zones, fractured intervals, calcite-filled joints, intrusive dikes, and volcanic bombs.

Anticipated Groundwater Levels: Long-term vibrating wire transducer monitoring indicates groundwater responds seasonally to winter precipitation and generally flows toward the west-southwest. Localized perched groundwater and hydraulic barriers associated with intrusive dikes or faults may occur. Groundwater observations shall be documented during drilling and considered when selecting instrumentation depths.

Drilling Equipment Needed: Rubber Track drill will be required, water truck and. truck rig may be utilized for a portion of the holes.

Number of holes @ __ feet 20 holes x 50 feet for an estimated total of 1,000 feet drilling max

Drilling Methods: HSA, HQ core SPT Testing Interval: Every 2.5’ to 20 feet then every 5’ Shelby Tubes, Other Sampling: If fine-grained cohesive soil with N<15 encountered Installations/Instrumentation: Install four (4) Vibrating Wire Transducers (VWTs) in designated borings. Instrumentation will be furnished by ODOT and installed in accordance with project specifications and OWRD requirements.

Type of Hole Abandonment: Per OWRD Rules and Regulations to full depth (20 holes) Driller Contact Information: TBD

HOLE LOGGER INFORMATION:

Project CEG: Jill DeKoekkoek Project CEG Reviewer: Scott Billings Field Geologist Brian McMullen Classification Method: GDM Chapter 5; ASTM

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Classification Sample Tests: To be sent to Materials Lab Other Testing Needed: TBD Laboratory Plan By: Geotechnical and Geology PORs Sample Testing Approved By: Geotechnical and Geology PORs Check Classification By: Geotechnical POR Final Logs By: Project CEG

Project Personnel:

Engineering Geology POR: Jill Dekoekkoek Engineering Geology Reviewer: Scott Billings Geotechnical Engineering POR: Brad Hayes Geotechnical Engineering Reviewer: Tomsen Reed

Contacts (In order):

Jill Dekoekkoek ODOT Mountain Unit Geology 541-452-1359 Brad Hayes ODOT Mountain Unit

Geotechnical 541-786-0905

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Boring No./ Location

For holes with VWT installation, see attached Subsurface Exploration Summary and Drill Hole Location Map. Elevation of VWTs should be approved by the Geotechnical or Geology POR prior to install.

All Holes

Advance borings using 4-inch inside diameter (I.D.) hollow-stem augers (HSA) through pavement (where present), embankment fill, and overburden soils.

Continue auger drilling until refusal or to a depth determined in the field by the ODOT Project Geologist or Geotechnical Engineer. Upon auger refusal, advance the boring using HQ3 triple-tube wireline coring to the planned termination depth.

Where competent bedrock is encountered, obtain a minimum of 15 feet of continuous rock core, or as directed by the ODOT Project Geologist.

Perform Standard Penetration Tests (SPTs) at 2.5-foot intervals from the ground surface to a depth of 20 feet, and at 5-foot intervals thereafter while advancing through soil. Where soft, cohesive soils are encountered (SPT N-value <15), obtain undisturbed Shelby tube samples at locations designated by the ODOT Project Geologist or Geotechnical Engineer.

If groundwater is encountered during drilling, suspend drilling for a minimum of 30 minutes prior to rock coring to allow groundwater levels to stabilize. Measure the stabilized groundwater level using an electronic water level meter or steel tape with a "popper" and record the depth to groundwater before continuing drilling operations.

Drilling operations may utilize either truck-mounted or rubber track-mounted geotechnical drill rigs, together with an appropriately sized water truck and support equipment. Most borings are located within cinder shoulders and ditch lines adjacent to the roadway, where a rubber track-mounted drill rig is expected to provide the safest and most efficient access.

Borings associated with one foundation footprint are located beyond the existing guardrail on a steep embankment (approximately 1V:1H (45°)). Depending on final traffic control and access constraints, these borings may be advanced from the roadway using a truck-mounted drill rig positioned adjacent to the guardrail.

Alternatively, if a section of guardrail can be temporarily removed, the borings may be advanced from the slope immediately behind the guardrail using a rubber track-mounted drill rig. The final drilling approach will be determined by ODOT based on site conditions, traffic control requirements, and contractor capabilities.

Borings located off the traveled way will generally require shoulder closures, while borings advanced from the roadway surface will require single-lane closures in accordance with the approved traffic control plan.

Notes: For hole locations, see Drill Hole Location Map.

Attachments:

Project Drill Hole Locations Map Site Photos

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Site Photos (All site photos are from 2023 site investigation)

West shoulder of South bound lane looking North

North bound land looking North