Attachment E (GeoTechReport)(For Informational Purposes Only)08192016.pdf

4660 Main Street, Suite 100-1A ● Springfield ● OR 97478

Phone: 541-393-6340 www.earth-engineers.com

August 19, 2016 Revised January 12, 2022

Abn Engineering, LLC Phone: (480) 213-8524 1337 East Desert Flower Lane Email: smane@abneng.com Phoenix, Arizona 85048 Attention: Sandeep Mane, P.E., S.E.

Subject: Geotechnical Investigation Report Proposed Wolf Mountain ODOT Communication Tower and Shelter - #F72005 Unnamed Forest Road from FR-527, Near Oakridge, Lane County, Oregon Latitude 43°36’59.86”N, Longitude -122°13’51.22”W EEI Report No. 15-201-1-R1

Dear Mr. Mane:

Earth Engineers, Inc. (EEI) is pleased to transmit our attached revised report for the above referenced project. This report includes the results of field and laboratory testing, an evaluation of geotechnical factors that may influence the proposed development, and engineering recommendations for foundation design and general site development. The report has been revised to address the most current project information you provided to us, to update the seismic recommendations so that they comply with the currently adopted version of the building codes (i.e. 2019 Oregon Structural Specialty Code and ASCE 7-16), and to clarify the bearing capacity recommendations. Revision additions are notated in bold, italics font.

We appreciate the opportunity to perform this geotechnical study and look forward to any continued participation you may need. If you have any questions pertaining to this report, or if we may be of further service, please contact our office.

Respectfully submitted, Earth Engineers, Inc.

Troy Hull, P.E., G.E. Greg Thibeaux, P.E.

Principal Geotechnical Engineer Geotechnical Engineer

Attachment: Geotechnical Investigation Report

Report Distribution (electronic copy only): Addressee

GEOTECHNICAL INVESTIGATION REPORT

For the

Proposed Wolf Mountain ODOT Communication Tower and Shelter Unnamed Forest Road from FR-527

Near Oakridge, Lane County, Oregon Latitude 43°36’59.86”N, Longitude -122°13’51.22”W

Prepared for

Abn Engineering, LLC 1337 East Desert Flower Lane

Phoenix, Arizona 85048

Prepared by

Earth Engineers, Inc.

4660 Main Street, Suite 100-A Street

Springfield, Oregon 97478 Telephone 541.393.6340

EEI Report No. 15-201-1-R1

August 19, 2016 Revised January 12, 2022

Greg Thibeaux, P.E.

Geotechnical Engineer

Troy Hull, P.E., G.E.

Principal Geotechnical Engineer

TABLE OF CONTENTS

Page No.

1.0 PROJECT INFORMATION

1.1 Project Authorization

1.2 Project Description

1.3 Purpose and Scope of Services

2.0 SITE AND SUBSURFACE CONDITIONS

2.1 Site Location and Description

2.2 Mapped Soils and Geology

2.3 Subsurface Materials

2.4 Groundwater Information

2.5 Seismicity

3.0 GEOTECHNICAL EVALUATION

3.1 Geotechnical Discussion

3.2 Site Preparation

3.3 Structural Fill

3.4 Tower Foundation Recommendations

3.5 Equipment Shelter Foundation Recommendations

3.6 Floor Slab Recommendations

3.7 Preliminary Retaining Wall Recommendations

3.8 Rock Anchor Recommendations

4.0 CONSTRUCTION CONSIDERATIONS

4.1 Moisture Sensitive Soils/Weather Related Concerns

4.2 Drainage and Groundwater Considerations

4.3 Excavations

5.0 REPORT LIMITATIONS

APPENDICES: APPENDIX A: TEST PIT LOGS

APPENDIX B: SOIL CLASSIFICATION LEGEND

APPENDIX C: ROCK CLASSIFICATION LEGEND

Wolf Mountain Tower and Shelter - #F72005 Earth Engineers, Inc.

EEI Report No. 15-201-1-R1 August 19, 2016 (revised January 12, 2022)

1.0 PROJECT INFORMATION

1.1 Project Authorization

Earth Engineers, Inc. (EEI) has completed a geotechnical investigation report for the proposed Oregon Department of Transportation (ODOT) communication tower located on Wolf Mountain, approximately 25 miles southeast of the town of Oakridge, in Lane County, Oregon. Our original services were authorized by Abn Engineering, LLC (Abn) on November 13, 2015 by issuing Purchase Order No. 2015-030. Our supplemental services to update this report were authorized by Abn on November 4, 2021 by issuing Purchase Order No. 2021-012.

1.2 Project Description

Our current understanding of the project is based on information provided by Mr. Sandeep Mane of Abn. The project information we have been provided to date includes:

• Set of revised drawings by the State of Oregon dated October 13, 2015, entitled “WOLF MTN #F72005. These drawings are stamped not for construction, and include a title sheet, zoning plan, enlarged site plan, tower elevations and details, ODOT project management contact information and general notes.

• U.S. Forest Service report #R2015061810009 entitled “Wolf Mountain Communication Site – ODOT Upgrade”, dated October 6, 2015.

• Drawing C-3 by Abn titled “Enlarged Site Plan,” dated January 6, 2021.

• Preliminary drawing LS-1 by Munson & Associates titled “Topographical Survey,” dated November 30, 2021.

In addition, EEI representative Ray Aliperti performed a visual site reconnaissance at the project site on October 22, 2015.

Briefly, we understand the new construction will include a 120-foot tall tower and new equipment shelter as part of the ODOT Wireless Communication Section Project, which is replacing aging public safety communications systems statewide (See Figures 1 and 2 below). There are existing structures on the site, including multiple towers and an equipment shelter. We are not aware if the existing towers and equipment shelter will remain. Note that our client (Sandeep Mane of Abn), U.S. Forest Service representative Terry Godin, and project CM, Karl Ryan, were present during our site investigation on August 2, 2016.

Figure 1: Site vicinity map (base map source: TOPO!4.2.3).

Project site

Figure 2: Enlarged site plan showing proposed tower, equipment shelter, existing propane tank locations in dashed lines and existing underground power line (base drawing source: Sheet C-3 by Abn Engineering, titled “Enlarged Site Plan,” dated January 6, 2021).

Table 1 below lists the approximate tower overall moment reaction at the tower base and the maximum reactions at each tower leg (note that these are factored reactions):

Table 1: Maximum Tower Loading Load Approximate Maximum Value*

Overall moment reaction at tower base 2,500 kip-ft Axial compression at each tower leg 300 kips

Uplift at each tower leg 265 kips Shear at each tower leg 30 kips

*Provided by project Structural Engineer, Mr. Sandeep Mane of Abn Engineering.

Other than underground utilities, no below ground construction or retaining walls are planned to our knowledge. We understand from our client that a mat foundation is the preferred foundation option and that, due to physical constraints at the site, the use of rock anchors may be necessary.

Existing propane tank

Proposed tower

Proposed shelter

Because grading plans have not been provided at this time, the magnitude of proposed cuts and fills on the site cannot be determined. Based on existing topography, we assume very little grading will be required (i.e. less than about two feet of cut and fill). We understand from the drawings that the proposed facility will be constructed in accordance with the provisions of the 2014 OSSC, an amendment to the 2012 IBC.

1.3 Purpose and Scope of Services

The purpose of this geotechnical evaluation was to perform an exploration of the site subsurface conditions to enable an evaluation of geotechnical factors that may influence the proposed development and to aid the structural engineer in designing the tower and equipment shelter foundations. The scope of services included two backhoe test pits. Disturbed bulk samples were obtained from the test pits as determined by our project Geotechnical Engineer. The excavations were loosely backfilled after the completion of our explorations. Note that the location of our explorations was constrained by the presence of protected historical features (described in U.S.

Forest Service report #R2015061810009 referenced above) and existing underground utilities (see Figure 2 above). Select soil samples were tested in the laboratory to determine the materials’ properties for our evaluation. Laboratory testing was accomplished generally in accordance with ASTM procedures.

This report briefly outlines the testing procedures, presents available project information, describes the site and subsurface conditions, and presents recommendations regarding the following:

• Description of the site.

• Discussion of subsurface soil and rock properties including groundwater conditions.

• Building code seismic site classification.

• Discussion of applicable geological hazards.

• Geotechnical related recommendations for mat foundation design, including soil bearing capacity, frost depth, lateral earth pressure and friction coefficient.

• Rock anchor design parameters based on an assumed bedrock to grout bond strength.

• Geotechnical foundation and floor slab recommendations for an equipment shelter.

• General retaining wall design parameters. The information provided to us does not show any planned retaining walls; we include general geotechnical recommendations for retaining walls at the request of Abn.

• Recommendations for overall site/soil preparation, including natural in-place soil and fill, and the overall suitability of the in-situ soils for use as utility backfill and structural fill.

• Discussions on geotechnical issues that may impact the planned construction.

2.0 SITE AND SUBSURFACE CONDITIONS

2.1 Site Location and Description

The site of the proposed tower and shelter is located approximately 25 miles southeast of Oakridge, Lane County, Oregon, at the peak of Wolf Mountain, at an elevation of 6,537 feet. The site location of the new construction is accessed by narrow gravel roads and is located west of existing communication towers and an existing propane tank. The site is sparsely vegetated covered with small trees, small to medium tree stumps, and sage brush. Gravel covers most of the grounds north and east of the site. The general area of the proposed construction slopes down gently to the north between about 5 and 10 degrees. Steep slopes, greater than 2H:1V (i.e.

western face of Wolf Mountain) are located about 40 to 50 feet west of the proposed tower and shelter.

Figure 3: Ariel view of project site (base image source: Google Earth).

Approximate location of proposed tower

Existing propane tank

Approximate location of proposed shelter

25 ft

N

Photo 1: Looking north at proposed location of tower and shelter, west of existing propane tank.

Photo 2: Looking south, site after backfill of test pits TP-1 and TP-2.

TP-1

TP-2

2.2 Mapped Soils and Geology

The site is located in the Cascade Range on Wolf Mountain, about 25 miles southeast of the town of Oakridge, in Lane County. This is an area of mid-elevation mountains with few perennial streams. The Cascades are built up by uplift and volcanism from the subduction of oceanic crust beneath the North American Plate. The geology of Wolf Mountain is mapped as Holocene to Pliocene aged (approximately 5.3 Ma), poorly to well-bedded, basalt to basalt andesite tuff, tuff breccia and minor lava flows (QTmv)1.

2.3 Subsurface Materials

The site was explored with two test pits (TP-1 and TP-2) in the general area of the proposed tower and equipment shelter. TP-1 and TP-2 were excavated to approximately five feet beneath the ground surface (bgs) using a subcontracted Komatsu WB 146 backhoe with a two-foot wide toothed bucket.

The ground surface in the area of TP-1 and TP-2 was covered with sparse vegetation and small trees, small to medium sized tree stumps, and exposed cobbles and boulders. At both TP-1 and TP-2, we encountered approximately 18 inches of red-brown, moist topsoil containing small to medium tree roots, and gravel and cobbles. Underlying the topsoil was approximately three feet of red-brown to gray-brown, moist, medium dense to dense, silty sand with gravel, containing mostly subangular cobbles and boulders (up to about 42 inches in width). Underlying the silty sand with gravel was gray-brown, hard, fractured basalt bedrock.

We encountered hard digging from approximately 24 inches bgs and encountered practical digging refusal using the backhoe referenced above at approximately five feet bgs on hard, fractured basalt bedrock in TP-1 and TP-2. No groundwater was encountered during our subsurface explorations.

1Sherrod, David R., 1991, Geologic Map of a Part of the Cascade Range Between Latitudes 43º- 44º, Central Oregon:

U.S. Geological Survey, Geologic Quadrangle Map I-1891, scale 1:125,000 http://ngmdb.usgs.gov/Prodesc/proddesc_1019.htm

Photo 3: Looking east at boulders excavated from TP-2.

The above subsurface description is of a generalized nature to highlight the major subsurface stratification features and material characteristics. The exploration logs included in Appendix A should be reviewed for specific information at specific locations. These records include soil descriptions, stratifications, results of laboratory testing, and locations of the samples. The stratifications shown on the logs represent the conditions only at the actual exploration locations.

Variations may occur and should be expected between locations. The stratifications represent the approximate boundary between subsurface materials; the actual transition may be gradual. The samples that were not altered by laboratory testing will be retained for 90 days from the date of this report.

2.4 Groundwater Information

Groundwater was not encountered in the explorations. Given the topography of the site, we anticipate that surface water sheet flows generally north from the proposed tower and shelter location, and down all sides of the mountain. Some surface water likely infiltrates the ground and seeps away through the fractured bedrock. We do not anticipate that shallow groundwater will be a problem during construction at this site.

2.5 Seismicity

In accordance with the 2019 OSSC and ASCE 7-16, we recommend a Site Class B (Rock) for this site when considering the average of the upper 100 feet. This recommendation is based on the results of our subsurface investigation as well as our understanding of the local geology.

Inputting our recommended Site Class as well as the site latitude and longitude into the Seismic Design Maps (SEAOC/OSHPD) website (http://seismicmaps.org), we obtained the seismic design parameters, shown in Table 2 below.

Table 2: Seismic Design Parameter Recommendations Parameter Recommendation

Ss 0.476g S1 0.260g Fa 0.9

FV 0.8

SMS (=Ss x Fa) 0.428g SM1 (=S1 x Fv) 0.208g

SDS (=2/3 x SMS) 0.286g SD1 (=2/3 x SM1) 0.139g

Design PGA (=SDS/2.5) 0.114g MCEG PGA 0.220g

FPGA 0.9

PGAM (=MCEG PGA x FPGA) 0.198g

Note: Site Latitude = 43.616628°, Site Longitude = -122.230894°

In accordance with the 2019 OSSC, Section 1803.5.11, we are including an evaluation of potential geologic and seismic hazards. These geologic and seismic hazards include slope instability, liquefaction, total and differential settlement, and surface displacement due to faulting or seismically induced lateral spreading or lateral flow.

The risk of earthquake surface rupture on the property is considered low due to the lack of mapped faults at or near the site based on our review of the United States Geological Survey’s web site and Interactive Fault Map at http://earthquake.usgs.gov/hazards/qfaults/map/. The USGS Quaternary Fault and Fold Database lists the nearest fault that has been active during the Quaternary period as the La Pine graben faults and unnamed faults north of Diamond Lake, approximately 15 to 20 miles east/southeast of the site. It should be noted that there could be faults that are active in the future that are not currently mapped.

http://seismicmaps.org/ http://earthquake.usgs.gov/hazards/qfaults/map/

The risk of liquefaction on the property is low when considering the site geology and the density of the native soils we encountered.

Given the risk of soil liquefaction is low, the risk of excessive total and differential dynamic settlement is also low, and we aren’t providing any mitigation recommendations. The risk of excessive total and differential static settlement (i.e. 1 and ½ inch, respectively) is very low provided the geotechnical engineering recommendations for foundations in Section

3.4 and 3.5 are followed.

The risk of slope instability on the property is considered moderate because there are steep slopes about 40 to 50 feet west of the site and because a review of the State of Oregon’s online landslide map (SLIDO-3.2) shows that the subject property is in a moderate landslide hazard area and near high landslide risk areas. Ancient mapped landslides are located within about 1.3 to 3 miles of the project site and historic, active landslides are located within about 0.5 miles of the site (see Figure 4 below). Our current scope of services does not include an evaluation of the global slope stability of the site vicinity.

Figure 4: State of Oregon’s online landslide map (SLIDO-3.2) showing ancient and active mapped landslides in vicinity of project site (base map source:

http://www.oregongeology.org/slido/ index.html).

Project site

Ancient mapped landslides

Historic, active landslides http://www.oregongeology.org/slido/%20index.html

3.0 GEOTECHNICAL EVALUATION

3.1 Geotechnical Discussion

The primary geotechnical factor influencing the proposed construction is shallow bedrock encountered at a depth of approximately five feet bgs. Hard digging in subangular gravel, cobbles and up to approximately 42 inch wide boulders was encountered from about two to five feet bgs.

If required, excavation into the rock formation will be difficult (i.e. heavy rock chipping and hammering will be required).

Information from our client, and available subsurface data, considered in conjunction with the provided development information, indicates that a mat foundation may be used to support the proposed tower provided that the site is developed in accordance with the requirements of this report. Rock anchors may also be appropriate, but drilling may be difficult into the shallow, fractured bedrock.

3.2 Site Preparation

Topsoil, vegetation, roots, stumps and any other deleterious soils will need to be stripped from development areas. A representative of the Geotechnical Engineer should determine the depth of removal at the time of construction. Utilities will need to be located and rerouted as necessary and any abandoned pipes or utility conduits should be removed to inhibit the potential for subsurface erosion. Utility trench excavations should be backfilled with properly compacted structural fill as outlined in Section 3.3 of this report.

The subgrade for the tower foundation and equipment shelter pad should be evaluated by a representative of the Geotechnical Engineer after they have been prepared. If fill is required, the structural fill should be placed on the prepared subgrade as outlined in Section 3.3 of this report after it has been observed and approved by a representative of the Geotechnical Engineer. Soils that are observed to be unsuitable by a representative of the Geotechnical Engineer should be undercut and replaced with properly compacted fill.

We recommend that, at the beginning of earthwork construction, the two loosely backfilled test pits (TP-1 and TP-2) be excavated to their bottoms and backfill with properly compacted granular structural fill under the observation of a representative of the Geotechnical Engineer.

3.3 Structural Fill

The on-site rocky soil material may be used as structural fill after any particles greater than eight inches have been removed. Care will need to be taken so that the rock is not loose and there are not large voids (i.e. nested cobbles and boulders). The contractor may need to process the material on site (i.e. crush it and/or sort it). If the native material is used with material between 3 and 8 inches in diameter, heavy equipment will be necessary to have enough compaction energy to properly compact it.

If the contractor elects to import granular structural fill material, it should be free of organic or other deleterious materials have a maximum particle size of three inches, be relatively well graded, and have fines with a liquid limit less than 45 and plasticity index less than 25. We recommend the structural fill be moisture conditioned to within 2 percentage points below and 2 percentage points above optimum moisture and compacted to within 95 percent of the materials maximum dry density as determined by ASTM D1557 (modified Proctor). If water must be added, it should be uniformly applied and thoroughly mixed into the soil by disking or scarifying.

Structural fill should be placed in a relatively uniform horizontal lift on the approved subgrade.

Each loose lift should be no greater than about 12 inches. The type of compaction equipment used will ultimately determine the maximum lift thickness. Each lift of compacted engineered fill should be tested by a representative of the Geotechnical Engineer prior to placement of subsequent lifts. Oversize fill material that cannot be tested for compaction should be approved visually by observing the fill placement method. The fill should extend horizontally outward beyond the exterior perimeter of structures at least five feet prior to sloping.

3.4 Tower Foundation Recommendations

As discussed earlier in the report, it is our understanding that a mat foundation is preferred. In order to provide a suitable bearing surface on which to support the mat foundation, it is recommended that it be supported on the dense, silty sand with gravel, containing mostly subangular cobbles and boulders, encountered in our explorations at a depth of approximately two feet below the ground surface. Where the exposed native soil is uneven, it would be acceptable to use relatively clean, granular fill to create a level pad for the mat.

For foundation bearing surfaces prepared as recommended above, it is our opinion that the proposed tower can be supported on conventional shallow spread footings designed for an allowable soil bearing pressure of up to 4,000 pounds per square foot (psf) when bearing on the dense silty sand with gravel, containing mostly subangular cobbles and boulders stratum. The allowable capacity includes a safety factor of 3 (i.e. ultimate capacity is 12,000 psf). The allowable bearing pressure of 4,000 psf is intended for dead loads and sustained live loads, and can be increased by one-third for the total of all loads, including short-term wind or seismic loads. The footings should extend a minimum depth of 24 inches beneath the lowest, adjacent, exterior grade in order to provide frost protection.

Note that because a Performance Based Design was used (i.e. we base the bearing capacity recommendation on settlement criteria), and not a bearing capacity calculation (i.e. Terzaghi), recommended allowable soil bearing pressure for depths of three, four and five feet below the ground surface are also 4,000 psf. This value assumes footings are not bearing directly on the fractured bedrock stratum.

Alternatively, it is our opinion that the proposed tower can be supported on conventional shallow spread footings designed for an allowable soil bearing pressure of up to 10,000 psf when bearing directly on the fractured bedrock stratum, encountered in our explorations at approximately five feet bgs. The allowable bearing pressure of 10,000 psf is intended for dead loads and sustained live loads, and can be increased by one-third for the total of all loads, including short-term wind or seismic loads. As stated above, the footings should extend a minimum depth of 24 inches beneath the lowest, adjacent, exterior grade in order to provide frost protection.

Allowable lateral frictional resistance between the base of footings and the silty sand stratum can be expressed as the applied vertical load multiplied by a coefficient of friction of 0.40. In addition, lateral loads may be resisted by passive earth pressures based on an equivalent fluid density of 300 pounds per cubic foot (pcf) for footings poured "neat" against in-situ rocky soils, or properly backfilled with structural fill. This recommended value includes a factor of safety of approximately 1.5, which is appropriate due to the amount of movement required to develop full passive resistance.

We estimate that foundations designed and constructed in accordance with the above recommendations will experience total static settlements generally less than 1-inch.

Surface run-off water should be drained away from the excavations and not be allowed to pond.

The foundation excavations should be observed by a representative of the Geotechnical Engineer prior to steel or concrete placement to assess that the foundation materials are capable of supporting the design loads and are consistent with the materials discussed in this report.

Unsuitable soil zones encountered at the bottom of the foundation excavations should be removed to the level of suitable soils as directed by the Geotechnical Engineer. Cavities formed as a result of excavation of unsuitable soil zones should be backfilled with lean concrete or compacted structural fill in accordance with Section 3.3 above.

3.5 Equipment Shelter Foundation Recommendations

Based on the results of our geotechnical investigation, it is our opinion that the proposed equipment shelter, assumed to be lightly loaded, can be supported by a shallow foundation or slab bearing on the dense, silty sand with gravel, containing mostly subangular cobbles and boulders stratum or structural fill overlying the silty sand stratum. Footings may be designed for an allowable bearing pressure of 4,000 psf. The allowable bearing pressure stated above includes a safety factor of at least 3 (i.e. ultimate capacity is 12,000 psf) and is intended for dead loads and sustained live loads and can be increased by one-third for the total of all loads, including short-term wind or seismic loads.

Note that because a Performance Based Design was used (i.e. we base the bearing capacity recommendation on settlement criteria), and not a bearing capacity calculation (i.e. Terzaghi), allowable soil bearing pressure for depths of three, four and five feet below the ground surface are also 4,000 psf. This value assumes footings are not bearing directly on the fractured bedrock stratum.

Alternatively, it is our opinion that the proposed equipment shelter can be supported on conventional shallow spread footings designed for an allowable soil bearing pressure of up to 10,000 psf when bearing directly on the fractured bedrock stratum, encountered in our explorations at approximately five feet bgs. The allowable bearing pressure of 10,000 psf is intended for dead loads and sustained live loads, and can be increased by one-third for the total of all loads, including short-term wind or seismic loads.

Minimum footing dimensions should be 18 inches for continuous wall footings and 24 inches for isolated column footings. Exterior footings in unheated areas should be located at a depth of at least 24 inches below the final exterior grade to provide adequate frost protection. If the building is to be constructed during the winter months or if the foundation soils will likely be subjected to freezing temperatures after foundation construction, then the foundation soils should be adequately protected from freezing. Otherwise, interior foundations can be located at nominal depths compatible with architectural and structural considerations.

Lateral frictional resistance between the base of footings and the subgrade can be expressed as the applied vertical load multiplied by a coefficient of friction of 0.40 for concrete foundations bearing directly on the silty sand with gravel, containing mostly subangular cobbles and boulders stratum. In addition, lateral loads may be resisted by passive earth pressures based on an equivalent fluid density of 300 pounds per cubic foot (pcf) for footings poured "neat" against in-situ rocky soils, or properly backfilled with structural fill. This recommended value includes a factor of safety of approximately 1.5, which is appropriate due to the amount of movement required to develop full passive resistance.

We estimate that foundations designed and constructed in accordance with the above recommendations will experience total static settlements generally less than 1-inch with differential static settlements between columns generally less than ½-inch.

Surface run-off water should be drained away from the excavations and not be allowed to pond.

The foundation excavations should be observed by a representative of the Geotechnical Engineer prior to steel or concrete placement to assess that the foundation materials are capable of supporting the design loads and are consistent with the materials discussed in this report.

Unsuitable soil zones encountered at the bottom of the foundation excavations should be removed to the level of suitable soils as directed by the Geotechnical Engineer. Cavities formed as a result of excavation of unsuitable soil zones should be backfilled with lean concrete or compacted structural fill in accordance with Section 3.3 above.

3.6 Floor Slab Recommendations

As noted above, we have not been provided with any maximum loading from the project structural engineer. For the purposes of this report, we have assumed that maximum floor slab loads will not exceed 150 psf. Floor slabs may be supported directly on the medium dense to dense silty sand stratum encountered in our explorations at approximately 18 to 24 inches bgs or on properly compacted structural fill (as outlined in Section 3.3 of this report) overlying the silty sand with gravel stratum.

Based on the existing soil conditions, the design of slabs-on-grade can be based on a subgrade modulus (k) of 250 pci. This subgrade modulus value represents an anticipated value which would be obtained in a standard in-situ plate test with a 1-foot square plate. Use of this subgrade modulus for design or other on-grade structural elements should include appropriate modification based on dimensions as necessary.

The subgrade under the proposed floor slab should be prepared and then observed by a representative of the Geotechnical Engineer as discussed in Section 3.2 of this report. Soils that are observed to be unsuitable by a representative of the Geotechnical Engineer should be undercut and replaced with properly compacted fill.

If additional protection against moisture vapor is desired (i.e. areas where there will be floor coverings) a moisture vapor retarding membrane should be incorporated into the design. Factors such as cost, special considerations for construction, and the type of floor coverings suggest that decisions on the use of vapor retarding membranes be made by the project architect and owner.

3.7 Preliminary Retaining Wall Recommendations

We are not aware of any retaining walls planned for this project. These retaining wall recommendations are being provided at the request of our client (Abn). If retaining wall plans are developed for this site, we should be retained to review them to verify that our recommendations have been incorporated into the plans. Additionally, our review may require a site reconnaissance to verify that the soil conditions in the area of the proposed retaining walls are consistent with those described in this report.

Retaining wall footings should be designed in general accordance with the recommendations contained in Section 3.5 above. Lateral earth pressures on walls, which are not restrained at the top, may be calculated on the basis of an “active” equivalent fluid pressure of 35 pcf for level backfill, and 60 pcf for sloping backfill with a maximum 2H:1V slope. Lateral earth pressures on walls that are restrained from yielding at the top may be calculated on the basis of an “at-rest” equivalent fluid pressure of 55 pcf for level backfill, and 90 pcf for sloping backfill with a maximum 2H:1V slope. The stated equivalent fluid pressures do not include surcharge loads, such as foundation, vehicle, equipment, etc., adjacent to walls, hydrostatic pressure buildup, or earthquake loading.

For seismic loading on retaining walls with level backfill, new research indicates that the seismic load is to be applied at 1/3 H of the wall instead of 2/3 H, where H is the height of the wall. We recommend that a Mononobe-Okabe earthquake thrust per linear foot of 2.2 psf* H2 be applied at 1/3 H, where H is the height measured from the base of the wall measured in feet. We used the updated Design PGA presented in Table 2 above in our calculation.

Lateral loads may be resisted by frictional resistance between the base of the retaining wall footing and the subgrade, and can be expressed as the applied vertical load multiplied by a coefficient of friction of 0.40 for concrete foundations bearing directly on the native soil. In addition, lateral loads may be resisted by passive earth pressures based on an equivalent fluid density of 300 pounds per cubic foot (pcf) for footings poured "neat" against in-situ rocky soils, or properly backfilled with structural fill. These are allowable values—we have applied a factor of safety of 1.5 to the equivalent fluid pressure, which is appropriate due to the amount of movement required to develop full passive resistance.

All backfill for retaining walls should be select granular material, such as sand or crushed rock with a maximum particle size between ¾ and 1 ½ inches, having less than 5 percent material passing the No. 200 sieve. The native material found on site is not expected to meet our wall backfill specification. However, depending upon the height and use of retaining walls, it’s possible that we may allow the use of the native material after it has been processed to remove the larger size particles. Silty soils may be used for the last 18 to 24 inches of retaining wall backfill, thus acting as a seal to the granular backfill. All backfill behind retaining walls should be moisture conditioned to within ± 2 percent of optimum moisture content, and compacted to a minimum of 90 percent of the material's maximum dry density as determined in accordance with ASTM D1557 (modified Proctor). Fill materials should be placed in layers that, when compacted, do not exceed about 8 inches. Care in the placement and compaction of fill behind retaining walls must be taken in order to insure that undue lateral loads are not placed on the walls.

3.8 Rock Anchor Recommendations

Based on the depth to bedrock in our explorations of five feet bgs, it is anticipated that the use of rock anchors for uplift resistance may be feasible for additional foundation uplift resistance. Rock anchors should consist of an all-thread rebar grouted in a drilled hole within competent bedrock;

in this case, hard, fractured basalt. The drilled hole should be a minimum of three inches in diameter, and extend a minimum of five feet into competent bedrock. Prior to grouting, the sides of the hole should be roughened to ensure adequate grout bonding, and the hole should be cleaned of loose debris. Grout should consist of a high performance, non-shrink grout. The all-thread bar should be adequately sized by a Structural Engineer to withstand the maximum uplift load at each anchor location. Based on our past experience, we recommend the rock anchors preliminarily be designed for an allowable side shear of 100 psi when embedded into the basalt bedrock.

In order to verify the above design side shear, it is recommended that at least one test anchor be installed at the site and proof tested. The test anchor should be loaded in 10 percent increments to two times the design load using a hydraulic ram system calibrated within the previous 12 months. Vertical movement (pullout) of the test anchor should be recorded to the nearest 0.001-inch at each loading increment using an independent dial gauge. Each incremental load should be held for a minimum of five minutes, and until vertical movement of the anchor has essentially ceased. The test result should be evaluated by the Geotechnical Engineer for load carrying capacity.

4.0 CONSTRUCTION CONSIDERATIONS

EEI should be retained to provide observation and testing of construction activities involved in the foundation, earthwork, and related activities of this project. EEI cannot accept any responsibility for any conditions that deviate from those described in this report, nor for the performance of the foundations if not engaged to also provide construction observation for this project.

4.1 Moisture Sensitive Soils/Weather Related Concerns

The upper sandy/rocky soils encountered at this site (i.e. silty sand with gravel, containing mostly subangular cobbles and boulders) are not expected to be overly sensitive to disturbances caused by construction traffic and to changes in moisture content.

4.2 Drainage and Groundwater Considerations

Water should not be allowed to collect in the foundation excavations or on prepared subgrades floor slabs during construction. Positive site drainage should be maintained throughout construction activities. Undercut or excavated areas should be sloped toward one corner to facilitate removal of any collected rainwater, groundwater, or surface runoff.

The site grading plan should be developed to provide rapid drainage of surface water away from the building areas and to inhibit infiltration of surface water around the perimeter of the building. The grades should be sloped away from building areas.

4.3 Excavations

In Federal Register, Volume 54, No. 209 (October 1989), the United States Department of Labor, Occupational Safety and Health Administration (OSHA) amended its "Construction Standards for Excavations, 29 CFR, part 1926, Subpart P". This document and subsequent updates were issued to better insure the safety of workmen entering trenches or excavations. It is mandated by this federal regulation that excavations, whether they be utility trenches, basement excavations or footing excavations, be constructed in accordance with the new OSHA guidelines. It is our understanding that these regulations are being strictly enforced and if they are not closely followed, the owner and the contractor could be liable for substantial penalties.

The contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The contractor's "responsible person", as defined in 29

CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in local, state, and federal safety regulations. We are providing this information solely as a service to our client. EEI does not assume responsibility for construction site safety or the contractor's compliance with local, state, and federal safety or other regulations.

5.0 REPORT LIMITATIONS

As is standard practice in the geotechnical industry, the conclusions contained in our report are considered preliminary because they are based on assumptions made about the soil, rock, and groundwater conditions exposed at the site during our subsurface investigation. A more complete extent of the actual subsurface conditions can only be identified when and if they are exposed during construction. Therefore, EEI should be retained as your consultant during construction to observe the actual conditions and to provide our final conclusions. If a different geotechnical consultant is retained to perform geotechnical inspection during construction then they should be relied upon to provide final design conclusions and recommendations, and should assume the role of Geotechnical Engineer of Record.

The recommendations submitted in this report are based on the available subsurface information obtained by EEI for the proposed project. If there are any revisions to the plans for this project, or if deviations from the subsurface conditions noted in this report are encountered, EEI should be notified immediately to determine if changes in the foundation recommendations are required. If EEI is not retained to review these changes, we will not be responsible for the impact of those conditions on the project.

The Geotechnical Engineer warrants that the findings, recommendations, specifications, or professional advice contained herein have been made in accordance with generally accepted professional geotechnical engineering practices in the local area. No other warranties are implied or expressed.

The Geotechnical Engineer should be retained and provided the opportunity to review the design plans and specifications to ensure that our engineering recommendations will be properly incorporated into the design documents. This report has been prepared for the exclusive use of ODOT Wireless Communications Section c/o Abn Engineering, LLC, ODOT and the other project team members for the specific application to the Wolf Mountain Communication Tower project located in Lane County, Oregon. EEI does not authorize the use of the advice herein nor the reliance upon the report by third parties without prior written authorization by EEI.

APPENDICES

APPENDIX A -

TEST PIT LOGS

D E

P T

H ft

S A

M P

L E

N O

S A

M P

L E

SOIL DESCRIPTION

D

IG

G

IN

G

F

F O

R T

P

A S

S

IN

G

S

IE

V

E

L

IQ

U

ID

L

IM

IT

P L

A S

T

IC

L

IM

IT

M O

IS

T

U R

E C

O N

T E

N T

P O

C K

E T

P E

N

(t s f)

REMARKS

Mod.

grab 1 Harder digging at 18 inches bgs.

Hard 26 34 Hard digging at 24 inches bgs.

grab 2 30

Hard

Groundwater not encountered at time of digging.

Mod. = moderate digging effort.

EARTH ENGINEERS, Inc.

Test pit terminated due to digging refusal on hard fractured bedrock at 5 feet bgs.

Transitions to gray-brown at about 4 feet bgs.

Test pit was loosely backfilled with the excavated soil and rock after completion.

Elevation from revised ODOT drawing entitled, "Title Sheet" dated 10-13-15.

APPENDIX A: TEST PIT TP-1

CLIENT: Abn Engineering, LLC EARTH ENGINEERS, INC. REPORT NO.: 15-201-1 PROJECT: Proposed Wolf Mountain Tower and Shelter EQUIPMENT: Komatsu WB 146 Backhoe, 2-foot wide, toothed bucket LOCATION: 25' W, 25' S of NW corner of existing propane tank fnd. APPROXIMATE ELEVATION: 6,537 feet above mean sea level DATE EXCAVATED: August 2, 2016

Backhoe scraping on cobbles and boulders at 18 inches bgs.

Backhoe scraping on hard bedrock at 4-1/2 to 5 feet bgs..

Topsoil - red-brown, moist, small to medium root systems, approximately 12 inches thick.

Silty Sand with Gravel - red-brown, moist, contained mostly subangular cobbles and boulders (boulders up to 36 inches wide), medium dense to dense.

Fractured Bedrock - gray-brown, dry to moist, basalt bedrock, hard.

LOGGED BY: Greg Thibeaux, E.I.

Ground covered with sparse vegetation, small trees and small to medium tree stumps. Boulders exposed at surface.

15-201-1 (Appendix A, Test Pit Logs, FINAL), TP-1

EQUIPMENT: Komatsu WB 146 Backhoe, 2-foot wide, toothed bucket

D E

P T

H ft

S A

M P

L E

N O

S A

M P

L E

SOIL DESCRIPTION

D

IG

G

IN

G

F

F O

R T

P

A S

S

IN

G

S

IE

V

E

L

IQ

U

ID

L

IM

IT

P L

A S

T

IC

L

IM

IT

M O

IS

T

U R

E C

O N

T E

N T

P O

C K

E T

P E

N

(t s f)

REMARKS

Mod.

grab 1 Harder digging at 18 inches bgs.

Hard Hard digging at 24 inches bgs.

grab 2 34 26

Hard Backhoe scraping on hard bedrock.

Groundwater not encountered at time of digging.

Mod. = moderate digging effort.

LOCATION: 24' W, 4' S of NW corner of existing propane tank fnd. APPROXIMATE ELEVATION: 6,537 feet above mean sea level

APPENDIX A: TEST PIT TP-2

CLIENT: Abn Engineering, LLC EARTH ENGINEERS, INC. REPORT NO.: 15-201-1 PROJECT: Proposed Wolf Mountain Tower and Shelter

Silty Sand with Gravel - red-brown, moist, contained mostly subangular cobbles and boulders, boulders up to 42 inches wide, medium dense to dense.

EARTH ENGINEERS, Inc.

DATE EXCAVATED: August 2, 2016 LOGGED BY: Greg Thibeaux, E.I.

Transitions to gray-brown at about 4 feet bgs.

Ground covered with sparse vegetation, small trees and small to medium tree stumps. Boulders exposed at surface.

Fractured Bedrock - gray-brown, dry to moist, basalt bedrock, hard.

Test pit terminated due to digging refusal on hard fractured bedrock at 5 feet bgs.

Test pit was loosely backfilled with the excavated soil and rock after completion.

Elevation from revised ODOT drawing entitled, "Title Sheet" dated 10-13-15.

Backhoe scraping on cobbles and boulders at 18 inches bgs.

Topsoil - red-brown, moist, small to medium root systems, approximately 18 inches thick.

15-201-1 (Appendix A, Test Pit Logs, FINAL), TP-2

APPENDIX B -

SOIL CLASSIFICATION LEGEND

APPENDIX B: SOIL CLASSIFICATION LEGEND

APPARENT CONSISTENCY OF COHESIVE SOILS (PECK, HANSON & THORNBURN 1974, AASHTO 1988)

Descriptor SPT N60 (blows/foot)*

Pocket Penetrometer, Qp (tsf)

Torvane (tsf) Field Approximation

Very Soft < 2 < 0.25 < 0.12 Easily penetrated several inches by fist Soft 2 – 4 0.25 – 0.50 0.12 – 0.25 Easily penetrated several inches by thumb

Medium Stiff 5 – 8 0.50 – 1.0 0.25 – 0.50 Penetrated several inches by thumb w/moderate effort Stiff 9 – 15 1.0 – 2.0 0.50 – 1.0 Readily indented by thumbnail

Very Stiff 16 – 30 2.0 – 4.0 1.0 – 2.0 Indented by thumb but penetrated only with great effort

Hard > 30 > 4.0 > 2.0 Indented by thumbnail with difficulty

* Using SPT N60 is considered a crude approximation for cohesive soils.

APPARENT DENSITY OF COHESIONLESS

SOILS (AASHTO 1988) MOISTURE

(ASTM D2488-06)

Descriptor SPT N60 Value (blows/foot) Descriptor Criteria Very Loose 0 – 4

Dry Absence of moisture, dusty, dry to the touch, well below optimum moisture content (per ASTM D698 or D1557) Loose 5 – 10

Medium Dense 11 – 30 Moist Damp but no visible water

Dense 31 – 50 Wet

Visible free water, usually soil is below water table, well above optimum moisture content (per ASTM D698 or D1557) Very Dense > 50

PERCENT OR PROPORTION OF SOILS

(ASTM D2488-06) SOIL PARTICLE SIZE

(ASTM D2488-06)

Descriptor Criteria Descriptor Size Trace Particles are present but estimated < 5% Boulder > 12 inches Few 5 – 10% Cobble 3 to 12 inches Little 15 – 25% Gravel - Coarse

Fine ¾ inch to 3 inches

No. 4 sieve to ¾ inch Some 30 – 45% Mostly 50 – 100% Sand - Coarse

Medium Fine

No. 10 to No. 4 sieve (4.75mm) No. 40 to No. 10 sieve (2mm)

No. 200 to No. 40 sieve (.425mm)

Percentages are estimated to nearest 5% in the field.

Use “about” unless percentages are based on laboratory testing. Silt and Clay (“fines”) Passing No. 200 sieve (0.075mm)

UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D2488)

Major Division Group Symbol Description

Coarse Grained

Soils

(more than 50% retained on #200 sieve)

Gravel (50% or more retained on No. 4 sieve)

Clean Gravel

GW Well-graded gravels and gravel-sand mixtures, little or no fines GP Poorly graded gravels and gravel-sand mixtures, little or no fines

Gravel with fines

GM Silty gravels and gravel-sand-silt mixtures GC Clayey gravels and gravel-sand-clay mixtures

Sand (> 50% passing No. 4 sieve)

Clean sand

SW Well-graded sands and gravelly sands, little or no fines SP Poorly-graded sands and gravelly sands, little or no fines

Sand with fines

SM Silty sands and sand-silt mixtures SC Clayey sands and sand-clay mixtures

Fine Grained Soils

(50% or more passing #200 sieve)

Silt and Clay (liquid limit < 50)

ML Inorganic silts, rock flour and clayey silts CL Inorganic clays of low-medium plasticity, gravelly, sandy & lean clays OL Organic silts and organic silty clays of low plasticity

Silt and Clay (liquid limit > 50)

MH Inorganic silts and clayey silts CH Inorganic clays or high plasticity, fat clays OH Organic clays of medium to high plasticity

Highly Organic Soils PT Peat, muck and other highly organic soils

GRAPHIC SYMBOL LEGEND

GRAB Grab sample SPT Standard Penetration Test (2” OD), ASTM D1586 ST Shelby Tube, ASTM D1587 (pushed) DM Dames and Moore ring sampler (3.25” OD and 140-pound hammer) CORE Rock coring

APPENDIX C -

ROCK CLASSIFICATION LEGEND

APPENDIX C: ROCK CLASSIFICATION LEGEND

WEATHERING DESCRIPTORS FOR INTACT ROCK (USBR, 2001)

Descriptor

Chemical Weathering-Discoloration- Oxidation

Mechanical Weathering and Grain Boundary

Conditions

Texture and Solutioning General

Characteristics Body of Rock

Fracture Surfaces

Texture Solutioning

Fresh No discoloration, not oxidized

No discoloration or oxidation

No separation, intact (tight)

No change No solutioning Hammer rings when crystalline rocks are struck

Slightly Weathered

Discoloration or oxidation limited to surface or short distance from fractures; some feldspar crystals are dull

Minor or complete discoloration or oxidation of most surfaces

No visible separation, intact

(tight) Preserved

Minor leaching of some soluble minerals may be noted

Hammer rings when crystalline rocks are struck; body of rock not weakened

Moderately Weathered

Discoloration or oxidation extends from fractures usually throughout; Fe-Mg minerals are “rusty,” feldspar crystals are

“cloudy”

All fracture surfaces are discolored or oxidized

Partial separation of boundaries visible

Generally preserved

Soluble minerals may be mostly leached

Hammer does not ring when rock is struck; body of rock is slightly weakened

Intensely Weathered

Discoloration or oxidation throughout; all feldspars and Fe-Mg minerals are altered to clay to some extent or chemical alteration produces in-situ disaggregation

All fracture surfaces are discolored or oxidized;

surfaces are friable

Partial separation;

rock is friable;

granitics are disaggregated in semi-arid conditions

Altered by chemical disaggregation such as via hydration or argillation

Leaching of soluble minerals may be complete

Dull sound when struck with hammer;

usually can be broken with moderate to heavy manual pressure or by light hammer blow; rock is significantly weakened

Decomposed

Discolored or oxidized throughout, but resistant minerals such as quartz may be unaltered; all feldspars and Fe-Mg minerals are completely altered to clay

Complete separation of grain boundaries (disaggregation)

Resembles a soil; partial or complete remnant rock structure may be preserved; leaching of soluble minerals usually complete

Can be granulated by hand; resistant minerals such as quartz may be present as “stringers” or “dikes”

RELATIVE STRENGTH OF INTACT ROCK BEDDING SPACING (modified USBR, 2001)

Descriptor Uniaxial Compressive Strength (psi) Descriptor Thickness or Spacing

Extremely Strong > 30,000 Massive > 10…