00017940 Geotech_Report For Informational Purposes Only.pdf

TELECOM

OREGON STATE RADIO PROJECT

TRANSMITTAL DOCUMENT

BLACK & VEATCH Proprietary and Confidential Page 1 of 2 CONTROLLED when read online OWIN-FM-00XX-000X Draft 051311 Printed copy is UNCONTROLLED

Site Name: Middle Mountain

Site Number: F71402

Deliverable:

Geotech Report

SOW REF # 5.2.6-5.2.6.5

Deliverable

REF#

5.2.6.6

TA# 146

To: Oregon State Radio Project

From: Black & Veatch Corporation

3210 Del Webb Ave, NE STE 110 Salem, OR 97301

5885 Meadows Road, Suite 700 Lake Oswego, OR 97035

Copies Site Name/Number Description/Deliverable 1 Middle Mountain / F71402 Geotech Report

These items are transmitted as checked:

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Delivered by Electronic Signature 8/20/2013 Alice Butler

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Transmittal No: 13-54 B&V Doc No: 0813 6

Date 8/20/2013

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Document Control;

Adapt Engineering

10725 SW Barbur Boulevard, Suite 200 Portland, Oregon 97219

Tel (503) 892-2346

Fax (503) 892-2348 www.adaptengr.com

August 14, 2013

Adapt Project No. OR13-17464-GEO

State Radio Project (SRP) c/o

Black & Veatch Corporation

5885 Meadows Road, Suite 700

Lake Oswego, Oregon 97035

Attention: Mr. Brady Lang

Subject: Geotechnical Engineering Evaluation

Middle Mtn. F71402

Gilhouley Road

Parkdale, Oregon 97712

Dear Mr. Lang:

Adapt Engineering (Adapt) is pleased to submit this report describing our recent geotechnical engineering evaluation for the Middle Mtn. F71402 tower site. The purpose of our work was to interpret general surface and subsurface site conditions in order to provide recommendations for design and construction. Our services were authorized by Black and Veatch Corporation

(BV) on behalf of the State of Oregon SRP Section.

Please note: The project for which this report has been prepared is part of the State

Radio Project (SRP). SRP will become the primary communications network used by police, fire, and emergency response services throughout Oregon. As such, this proposed communication tower falls within the definition of an “Essential Facility” as defined in the 2011 Oregon Revised Statutes (ORS) Section 455.447. According to

Section 1803.3.2 of the 2010 Oregon Structural Specialty Code, sites for structures and facilities defined by ORS 455.447 as “Essential Facilities” shall be evaluated on a site specific basis for vulnerability to seismically induced geologic hazards. Our scope of work did NOT include such an assessment, as we were not authorized to perform a Site

Specific Seismic Hazard Investigation for this site.

As such, this geotechnical report addresses only a portion of the Oregon Structural

Specialty Code. It is our understanding that any additional analysis and reports necessary to comply with the Oregon Structural Specialty Code as it relates to the required Site Specific Seismic Hazard Investigation remains the responsibility of Black and Veatch Corporation and the SRP.

With the above exception, we prepared this report in accordance with generally accepted geotechnical engineering practices at the time we prepared it, for the exclusive use of Black and

Veatch, the State of Oregon SRP, and their agents, for specific application to this project. Use or reliance upon this report by a third party is at their own risk. Adapt does not make any representation or warranty, express or implied, to such other parties as to the accuracy or completeness of this report or the suitability of its use by such other parties for any purpose whatever, known or unknown, to Adapt.

We appreciate the opportunity to be of service to you. If you have any questions, or if we can be of further assistance to you, please contact us at (503) 892-2346.

Respectfully Submitted, Robert Nystrom, R.G. Jeanne Niemer, P.E., G.E.

Staff Geologist Senior Geotechnical Engineer

Attachment A Figures

Figure 1 Location/Topographic Map

Figure 2 Site & Exploration Plan

Attachment B Subsurface Exploration Logs

10725 SW Barbur Boulevard, Suite 200

Portland, Oregon 97219

Tel (503) 892-2346 Fax (503) 892-2348 www.adaptengr.com

Oregon State Radio Project c/o Black and Veatch

Geotechnical Engineering Evaluation

Middle Mtn. F71402 Tower Site

Parkdale, Oregon

OR13-17464-GEO

August 2013

SRP c/o Black & Veatch – Middle Mtn. F71402 August 14, 2013 Adapt Project No. OR13-17464-GEO page 5

PROJECT DESCRIPTION

The site is located at the top of Middle Mountain off of Gilhouley Road, near Parkdale, in Hood

River County, Oregon, as shown on the attached Location/Topographic Map (Figure 1). The project will consist of constructing a 140-foot tall self-support communication tower in and existing communication compound on the host property. No equipment shelter or new access road will be part of the new construction.

SITE CONDITIONS

Surface Description

The area of planned construction is currently vacant, covered with dirt and gravel, and has been graded level. There was no standing water present at the time of our exploration.

Subsurface Conditions

We explored the subsurface conditions at the project site on August 12, 2013. Our subsurface exploration consisted of advancing one test pit (designated TP-1) near the proposed tower, as shown on the attached Site and Exploration Plan (Figure 2). We logged and classified the subsurface materials in general accordance with the Manual Visual Classification Method

(ASTM D 2488).

We encountered about six inches of dense, sandy gravel overlying slightly weathered, closely fractured basalt bedrock. We terminated the test pit on very strong basalt bedrock at approximately 6.0 feet bgs.

We did not encounter groundwater, seeps or seams at the time of our exploration; however, groundwater levels may fluctuate in response to changing precipitation patterns, off-site construction activities, and changes in site utilization.

CONCLUSIONS

Based on our exploration and analyses, the site can be developed as proposed provided that the work is performed in general accordance with our recommendations presented below.

The proposed tower can be supported on a structural mat foundation that derives its support from the hard basalt bedrock. Due to the shallow bedrock we anticipate that rock anchors may be required to provide additional resistance against lateral, overturning, or uplift forces acting on the foundation. The use of blasting techniques, larger hydraulic excavators and/or bulldozers with ripping teeth may be required to advance the excavations into the basalt bedrock.

Our specific geotechnical design and construction recommendations are presented in the following sections.

Adapt Project No. OR13-17464-GEO page 6

GEOTECHNICAL DESIGN RECOMMENDATIONS

Mat Foundation The base of the mat foundation should be founded at a minimum depth of three feet bgs, on the hard basalt bedrock. After excavation to design grade, the subgrade should be cleaned of material loosened by excavation. Irregularities resulting from the excavation should be filled with sand, lean concrete, or other suitable material to produce a level bearing surface for the foundation.

We recommend using an allowable bearing capacity of 6,000 pounds per square foot (psf) for foundations bearing on the hard basalt. We estimate post construction settlements will be less than one inch.

Lateral loads acting on the foundations can be resisted by passive earth pressure on one side of the foundation and by friction along the soil-concrete interface at the base of the foundation.

We recommend using an allowable passive earth pressure of 400 pounds per cubic foot (pcf) for foundations confined by basalt bedrock. We recommend an allowable coefficient of interface friction of 0.40 for foundations bearing on basalt bedrock. In order to develop these capacities, concrete must be poured neat in excavations, the adjacent grade must be level, and the static ground water level must remain below the base of the footing throughout the year. The passive pressure within the upper two feet of embedment should be neglected. These allowable lateral resistance values include a minimal factor of safety of 1.5.

Eccentric loads and moments acting on the foundation produce a skewed bearing pressure distribution to the ground. The mat foundation should be sized so that the resultant load acts within the middle third of the foundation for one-way and two-way eccentric loading to maintain a compressive contact pressure along the base of the foundation. The maximum bearing pressure from the eccentric loading must be less than the allowable bearing pressure.

Rock Anchors Rock anchors, if needed to resist uplift loads, should be installed a minimum of 10 feet into the underlying basalt bedrock. We recommend using an allowable grout/ground interface bond strength of 60 psi for the basalt. The upper two feet of embedment should be ignored for design purposes. The allowable grout/ground bond strength includes a factor of safety of 3. Rock anchors should be designed to meet the loading conditions as specified by the structural engineer.

Rock anchors should consist of steel bars installed in the center of a grouted drill hole. Steel bars should consist of #8 or larger deformed thread bar, in accordance with ASTM A 615, Grade

60 minimum and should be epoxy coated or hot dip galvanized for corrosion protection. The drill hole should be cleaned of deleterious material prior to placement of grout and steel and

Adapt Project No. OR13-17464-GEO page 7 should be a minimum of one inch larger than the anchor diameter or as needed to provide sufficient cover between the ground and steel. Centralizers should be placed along the steel bar at a minimum of three feet from the bottom of the steel bar and three feet from the top of the steel bar with a maximum spacing of 10 feet. Centralizers shall be fabricated from schedule 40

PVC pipe, steel, or material non-detrimental to the reinforcing steel. Wood shall not be used.

Grout properties and mix design shall be as specified by the structural engineer.

Group effects should be accounted for by either providing the minimum spacing recommended below or by a reduction in capacity that can be calculated once on the proposed anchor arrangement is established. We recommend using a minimum anchor spacing of six diameters on center.

Installation records for each rock anchor installed should be prepared. Installation records should include, at a minimum, drilling equipment and procedures, ground conditions during drilling, anchor number, anchor design load, type and size of reinforcing steel, total anchor length, and grout properties.

Verification Tests: We recommend that pre-production verification testing be performed on at least one anchor to verify the design of the anchor system and the construction methods proposed prior to installing the remaining production anchors. We should review the results of the verification test prior to beginning installation of the remaining anchors. The maximum verification test load (VTL) should be 200 percent of the design load (DL), as established by the structural engineer.

Proof Tests: Proof tests should be performed on the remaining anchors to verify consistent ground conditions and construction performance. The maximum proof test load (PTL) should be 120 percent of the DL.

We recommend that a representative from Adapt be present for the duration of rock anchor construction and testing.

Foundation Construction Considerations

A geotechnical engineer from Adapt (or their representative) should confirm suitable bearing conditions and evaluate the foundation subgrades. Observations should also confirm that loose or soft material, organics, unsuitable fill, or old topsoil zones were removed. Localized deepening of footing excavations may be required to penetrate any deleterious materials.

Because foundation stresses are transferred outward as well as downward into the bearing soils, all footing over-excavations should extend horizontally outward from the footing edge a distance equal to the one half the over-excavation depth for the structural backfill.

Adapt Project No. OR13-17464-GEO page 8

Seismic Design Parameters Based on our analysis and understanding of the site, we interpret the on-site subsurface conditions to correspond to Site Class C, as defined by Table 1613.5.2 of the 2009 International

Building Code. Our recommended seismic design parameters are summarized in Table 1.

Table 1

Seismic Design Parameters

Short Period 1 Second

Maximum Credible Spectral Acceleration SS=0.372 S1=0.152

Site Coefficient Fa=1.200 Fv=1.65

Design Spectral Response Acceleration Parameters SDS=0.298 SD1=0.167

Site Class C

Based on the lack of groundwater and the shallow bedrock, we conclude that the potential for liquefaction during a design level earthquake is negligible. For purposes of seismic site characterization, we extrapolated the soil conditions that we observed below the exploration termination depth, based on our knowledge of the regional geology.

CONSTRUCTION RECOMMENDATIONS

Site Preparation

Clearing and Stripping: After surface and near-surface water sources have been controlled, the construction areas should be cleared and stripped of organic matter and other deleterious materials. Silt fences, hay bales, buffer zones of natural growth, sedimentation ponds, and granular haul roads should be used as required to reduce sediment transport during construction to acceptable levels.

Where present, existing topsoil should be stripped and removed from proposed development locations and for a five-foot-margin around such areas. Based on our explorations, we anticipate the depth of stripping to be less than one foot, although greater stripping depths may be required if deleterious materials are encountered. Deleterious materials encountered during site preparation should be removed from the subgrade soils and hauled off site for disposal.

Stripped material should be transported off site for disposal or stockpiled for use in landscaped areas.

Adapt Project No. OR13-17464-GEO page 9

Excavations: Temporary soil cuts associated with site excavations or regrading activities should be adequately sloped back to prevent sloughing and collapse, unless a shoring box or other suitable excavation side wall bracing is provided. It is the responsibility of the contractor to ensure that excavations are properly sloped or braced for worker safety protection, in accordance with OSHA safety guidelines.

Dewatering: Based on our subsurface exploration, we do not anticipate groundwater seepage within the tower mat excavation. If water is encountered, we anticipate that pumping from sumps located in the trench will likely be effective in removing water resulting from seepage or perched groundwater.

Final Grades: Final site grades should slope downward away from the structure at a minimum of two percent and runoff should be conveyed to a suitable drainage outlet. Alternatively, the area surrounding the structure could be capped with concrete, asphalt or compacted, low-permeability soils to reduce surface water infiltration into the subsurface soils near the foundation.

Structural Fill Materials: Structural fill includes any fill material placed under footings, roads, or other improvements. Typical materials used for structural fill include: clean, well-graded sand and gravel; clean sand; crushed rock; controlled-density fill (CDF); lean-mix concrete; and various soil mixtures of silt, sand, and gravel. Recycled concrete, asphalt, and glass derived from pulverized parent materials may also be used as structural fill. Use of the on-site soils as structural fill is also feasible.

Placement and Compaction: When used as structural fill, the on-site soils should be placed in lifts with a maximum thickness of 8 inches and compacted to not less than 92 percent of the material’s maximum dry density, as determined by ASTM D-1557. If the on-site soils cannot be properly moisture-conditioned, we recommend using imported granular material for structural fill.

Particles larger than four inches should be screened from the on-site soil.

Imported granular structural fill should consist of angular pit or quarry run rock, crushed rock, or crushed gravel and sand that is fairly well graded between coarse and fine particle sizes. The fill should contain no organic matter or other deleterious materials, have a maximum particle size of one inch, and have less than 5 percent passing the U.S. No. 200 Sieve. The percentage of fines can be increased to 12 percent of the material passing the U.S. No. 200 Sieve if placed during dry weather and provided the fill material is moisture-conditioned, as necessary, for proper compaction. The material should be placed in lifts with a maximum uncompacted thickness of 12 inches and be compacted to not less than 95 percent of the maximum dry density, as determined by ASTM D-1557. During the wet season or when wet subgrade

Adapt Project No. OR13-17464-GEO page 10 conditions exist, the initial lift thickness should be increased to 24 inches and should be compacted by rolling with a smooth-drum, nonvibratory roller.

CDF and lean-mix concrete do not require special placement or compaction procedures.

Regardless of location or material, all structural fill should be placed over firm, unyielding subgrade soils. If earthwork takes place during freezing conditions, we recommend that exposed subgrades be allowed to thaw and be recompacted prior to placing subsequent lifts of structural fill.

CONSTRUCTION OBSERVATIONS

Satisfactory earthwork performance depends on the quality of construction. Sufficient monitoring of the contractor’s activities is a key part ensuring that work is completed in accordance with the construction drawings and specifications. We recommend that a representative from Adapt observe that the subsurface conditions observed during our site investigation are consistent with those encountered during construction, and that foundation subgrades are suitable for placement of structural fill, rebar, or concrete for the new structures.

CLOSURE

We have prepared this report for use by the owner/developer and other members of the design and construction team for the proposed Middle Mountain tower site. The opinions and recommendations contained within this report are not intended to be, nor should they be, construed as a warranty of subsurface conditions, but are forwarded to assist in the planning and design process.

We have made observations based on our explorations that indicate the soil conditions at only those specific locations and only to the depths penetrated. These observations do not necessarily reflect soil types, strata thickness, or water level variations that may exist in other locations. If subsurface conditions vary from those encountered in our site exploration, Adapt should be alerted to the change in conditions so that we may provide additional geotechnical recommendations, if necessary. The future performance and integrity of the improvements will depend largely on proper initial site preparation, drainage, and construction procedures.

Observation by experienced geotechnical personnel should be considered an integral part of the construction process.

The conclusions and recommendations contained in this report are based on our understanding of the currently proposed project, as we derived from information that you provided. When the design has been finalized, we recommend that we review the design and specifications to see that our recommendations have been interpreted and implemented as intended. If design changes are made, we request that we be retained to review our conclusions and recommendations and to provide a written modification or verification.

Adapt Project No. OR13-17464-GEO page 11

The scope of our services does not include services related to construction safety precautions, and our recommendations are not intended to direct the contractor’s methods, techniques, sequences, or procedures, except as specifically described in our report for consideration in design.

Within the limitations of scope, schedule, and budget, our services have been executed in accordance with the generally accepted practices in this area at the time this report was prepared. No warranty or other conditions, express or implied, should be understood.

SRP c/o Black & Veatch – Middle Mtn. F71402 Attachment A

ATTACHMENT A

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Middle Mtn F71402 Geotech Report_Rev 1