J10 - Attachment 10_Bald Falls River Bridge-Geotech.pdf

REPORT OF

GEOTECHNICAL EXPLORATION

BALD RIVER FALLS BRIDGE REPLACEMENT

CHEROKEE NATIONAL FOREST

Prepared for:

USDA FOREST SERVICE

CHEROKEE NATIONAL FOREST

2800 North Ocoee Street Cleveland, Tennessee 37312

Prepared by:

AMEC Environment & Infrastructure, Inc.

396 Plasters Avenue NE Atlanta, Georgia 30324

(404) 873-4761

October 2, 2012

Project No. 6163-12-0182.03

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee iii October 2, 2012

TABLE OF CONTENTS

Page

1.0 INTRODUCTION

1.1 PROJECT INFORMATION

2.0 EXPLORATION PROCEDURES

3.0 GENERAL SITE AND SUBSURFACE CONDITIONS

3.1 AREA AND SITE GEOLOGY

3.2 SUBSURFACE CONDITIONS

4.0 CONCLUSIONS AND RECOMMENDATIONS

4.1 SITE PREPARATION

4.2 FILL PLACEMENT

4.3 EXCAVATION

4.4 BRIDGE FOUNDATIONS

4.4.1 Drilled Shaft Recommendations

4.5 GROUND WATER MANAGEMENT

4.6 RETAINING WALL RECOMMENDATIONS

4.7 DRAINAGE

4.8 ROCK ANCHORS

4.9 PERMANENT AND TEMPORARY SLOPES

4.10 ADDITIONAL EXPLORATION

5.0 QUALIFICATIONS OF RECOMMENDATIONS

APPENDIX

Figure 1. Boring Location Plan

Figure 2. Cross Section

Field Testing Procedures

Key to Boring Symbols

Soil Test Boring Records (4)

Photographic Records (7)

Laboratory Test Results

ASFE Information on Geotechnical Reports

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 1 October 2, 2012

REPORT OF GEOTECHNICAL EXPLORATION

Bald River Falls Bridge

Tellico River Road, Monroe County, Tennessee

1.0 INTRODUCTION

AMEC (formally known as MACTEC Engineering & Consulting, Inc.) has completed a preliminary geotechnical exploration for the proposed Bald River Falls Bridge replacement project in Monroe

County, Tennessee. The objective of this study was to explore the subsurface conditions within the area of the proposed bridge and to analyze these conditions as they relate to foundation design and construction. This report briefly discusses our understanding of the project, describes our exploratory procedures and presents our conclusions and preliminary recommendations.

1.1 PROJECT INFORMATION

We understand that the replacement of the Bald River Falls Bridge on Tellico River Road, No. 210 is planned. The bridge is located along Tellico River Road approximately 11 miles east-southeast of

Tellico Plains in Monroe County, Tennessee.

The existing 77 year old bridge is a steel and concrete deck structure supported on two bents (of two piers each) and abutment walls at either end of the bridge. The bridge superstructure shows some signs of deterioration and the abutments have significant loss of soil and signs of erosion. The topography of the bridge area is generally relatively steep. Access to the bridge abutments is significantly constrained.

A structural evaluation of the existing bridge and an evaluation of three alternatives for replacement/rehabilitation of the existing bridge and solutions to enhance pedestrian viewing of the

Bald River Falls were performed by AMEC in November, 2010. The evaluated alternatives included

(i) rehabilitation of the existing bridge by performing repairs and construction of a new pedestrian bridge,(ii) rehabilitation of the existing bridge by performing repairs to convert it to a pedestrian bridge and construction of a new vehicular bridge, and (iii) complete removal of the existing bridge and construction of a new vehicular and pedestrian bridge.

We understand the construction of a new bridge serving as both a vehicular and pedestrian bridge has been selected and is a modification of the three options outlined above. The current intent is to have the current bridge in service while a new, adjacent bridge is constructed. The new vehicular bridge will have an approximate span of 190 feet and a width of 37 feet. A 12 foot wide pedestrian bridge lane would be added and would be isolated from the vehicular lanes by an appropriate railing.

After the new bridge is constructed the existing older bridge will be removed.

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 2 October 2, 2012

2.0 EXPLORATION PROCEDURES

Subsurface conditions at this site were explored by performing four soil test borings, designated B-1 through B-4, at the approximate locations shown on the Boring Location Plan, Figure 1, in the

Appendix. All of the borings were drilled at the abutments since access at the river level was not feasible at this time. Soil test borings were drilled to auger refusal (encountered at depths ranging from 3 to 6 feet) and then extended between 21 to 35 feet below refusal using rock coring methods.

Boring locations were established in the field by AMEC personnel using a tape measure and referencing established site features. As-built survey information (location) was provided by USDA

Forest Service via email on August 2, 2011. Boring elevations were interpolated from the provided survey drawing. Because these measurements are not precise, the elevations on the Soil Test Boring

Records should be considered approximate.

The borings were drilled using a track-mounted drill rig to advance continuous flights of hollow-stem augers through soil. At regular intervals, Standard Penetration Tests (SPT) were conducted through the center of the auger with a standard 1.4-inch I.D., 2-inch O.D., split-barrel sampler. The sampler was first seated six inches to penetrate any loose cuttings and then driven an additional foot with blows of a 140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot was recorded and is designated the “standard penetration resistance”, or “N-value”. The standard penetration resistance, when properly evaluated, is an index to soil strength, consistency, and ability to support foundations. Refusal materials were cored with a diamond-studded bit attached to the end of a hollow double-tube core barrel. This device was rotated at high speeds and is capable of cutting very hard rock. The cuttings were brought to the surface by circulating water. Rock core samples of the materials penetrated were protected and retained in a swivel-mounted inner tube. Upon completion of the drill run, the core barrel was brought to the surface and the samples were removed. All drilling and sampling operations were performed in general accordance with ASTM designations as outlined in the Appendix.

Soil samples obtained from the standard penetration tests were visually classified and logged in the field by a geologist. Soil classifications were performed in general accordance with the Unified Soil

Classification System (USCS) using visual/manual methods. Detailed descriptions of the materials encountered in each boring, along with graphic representations of standard penetration testing, are presented on the individual Soil Test Boring Records included in the Appendix. These records represent our interpretation of the subsurface conditions based on the field logs and an engineering examination of the samples. The groundwater condition indicated on the Soil Test Boring Record represents observations at the time of drilling. The lines designating the interfaces between various strata represent approximate boundaries only, as transitions between materials may be gradual. Soil samples will be discarded after 30 days from the date of this report unless otherwise requested.

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 3 October 2, 2012

The assessment of site environmental conditions or the detection of pollutants in the soil, rock, or groundwater at the site was beyond the scope of the geotechnical exploration.

3.0 GENERAL SITE AND SUBSURFACE CONDITIONS

3.1 AREA AND SITE GEOLOGY

Published geologic information (Bulletin 58, Geologic Map of East Tennessee, 1953) indicates the site may be underlain by the Great Smoky Conglomerate. The bedrock of the Great Smoky

Conglomerate consists primarily of greywacke sandstone and conglomerate in thick graded beds, with partings of slate between many of the layers.

3.2 SUBSURFACE CONDITIONS

The soil test borings performed at the site encountered fill underlain by bedrock consistent with the mapped geology.

Fill may be any material that has been transported and deposited by man. Fill described as medium dense to dense, yellow brown and gray gravel with varying amounts of silt and clay was encountered.

Standard penetration resistances in the fill ranged from 6 blows per foot (bpf) to 55 bpf.

Beneath the fill, auger refusal material was encountered at depths ranging from about 3 to 6 feet.

Auger refusal is a designation applied to any material which cannot be further penetrated by the soil drilling process and is normally indicative of a very hard or very dense material, such as boulders, rock lenses or the upper surface of bedrock. Shallow refusal material encountered in borings B-2 and

B-3 was described as sandstone boulders and rubble fill. Below the fill in all of the borings, refusal material described as moderately to highly weathered, very soft to moderately hard, gray to dark gray, moderately to highly fractured/jointed, fine to coarse grained sandstone with sandy siltstone lenses was encountered. Core recovery was 0 to 100% and rock quality designation was 50 to 95.

Groundwater was at 28 feet (approximate Elevation 1343 feet) in boring B-3 at the time of drilling.

Groundwater levels fluctuate with seasonal and climatic variations and may be different at other times.

The borings were backfilled with soil cuttings prior to demobilizing from the site. The subsurface conditions may vary between exploration locations; therefore, our individual soil test logs in the

Appendix should be referenced to estimate conditions at specific test locations at the time of exploration.

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 4 October 2, 2012

4.0 CONCLUSIONS AND RECOMMENDATIONS

The following conclusions and recommendations are based on the previously discussed project information and assumptions, our observations at the site, interpretation of the field data obtained during the exploration, and our experience with similar subsurface conditions. At this time, we have general information about the proposed development. However, specific information including foundation loads and abutment information have not been provided. Additional consultation and/or investigation will be required as the project develops to confirm the assumptions presented below and to verify that the recommendations are appropriate for the final design.

4.1 SITE PREPARATION

The proposed alternative of replacement of the existing bridge includes the demolition/removal of the existing bridge and the realignment of a section of the roadway. The new alignment will be generally north east of and level with the existing roadway alignment. The new roadbed will generally bear on fill.

All vegetation, root systems, topsoil, loose soils, boulders and other deleterious non-soil materials should be stripped from proposed construction areas. After clearing and stripping, areas intended to support structures, including new fill, should be carefully assessed by a qualified geotechnical engineer or his representative.

Excavations created below subgrade levels during the demolition should be backfilled with compacted soil or aggregate fill placed in accordance with the recommendations of this report.

We recommend proof rolling subgrades for roadways and areas to receive compacted fill (if practical) as discussed below to identify soft subgrade areas. Proof rolling should be done after a suitable period of dry weather to avoid degrading an otherwise acceptable subgrade. Proof rolling should be performed with a heavily loaded dump truck or with similar approved construction equipment. The proof rolling equipment should make at least four passes over each section, with the last two passes perpendicular to the first two where practical.

We recommend exposed subgrades and proof rolling operations be observed and documented by qualified geotechnical personnel. We recommend actual subgrade stabilization requirements, if deemed necessary, be determined at the time of site preparation, based on observations of the subgrade and the stability of the subgrades as determined during proof rolling or other methods determined at time of construction. Loose, soft, organic, highly plastic, excessively wet soils that pump, rut, or wave during site grading or proof rolling operations should be removed or stabilized.

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 5 October 2, 2012

If soft soils are encountered in roadway areas, they are typically mitigated by undercutting the soft soils to expose competent soils and then backfilling with compacted fill to plan subgrade levels or by undercutting poor subgrade soils to some depth and then placing a high-modulus geotextile, geogrid and/or layer of aggregate to establish a stable platform upon which to backfill with compacted fill.

During the excavation and grading, positive surface drainage should be maintained to prevent the accumulation of water. Pumping from sumps may be required in undercut excavations. If the exposed subgrade becomes excessively wet or frozen, or if conditions different from those described previously in this report are encountered, a qualified geotechnical engineer should be consulted. Wet weather, freeze/thaw, and construction activity can all contribute to subgrade degradation. The contractor should perform final subgrade preparations shortly before roadways are to be constructed.

Fine-grained silty and clayey soils that may be encountered near the ground surface will not support construction traffic as they get wet. Therefore, where these soils are encountered the contractor should anticipate additional subgrade stabilization will be required during and shortly after wet periods to repair fine-grained soil subgrade areas damaged by construction traffic.

4.2 FILL PLACEMENT

Fill material to replace undercut areas or achieve finished grades should be low to moderate plasticity soil (PI less than 30), free of deleterious materials and rock fragments larger than 6 inches in diameter. Fill should be placed in maximum 8-inch thick loose lifts and compacted to at least 95 percent of the soil's maximum dry density as determined by the standard Proctor compaction test

(ASTM D 698). The upper 8 inches of soil beneath pavements should be compacted to at least 98 percent. Soil moisture during placement should be maintained within 3 percent above or below the optimum moisture content determined by ASTM D 698. Depending on weather conditions and the water content of fill sources, some moisture control may be required. Fill material should be placed in horizontal lifts and adequately keyed into stripped and scarified subgrade soils.

For this project, it is likely impractical to stockpile or dry soil fills at or near the site. Therefore, select granular backfill, such as crushed quarry stone (ASTM #57 stone or equivalent Graded Aggregate

Base), which has considerable benefits in strength, drainage, and ease of compaction over soils, may be an attractive alternative. The cost of transportation to and from the site will likely comprise most of the fill cost, so the marginal cost for select backfill may be minor relative to the benefits derived.

Since most fill will serve as backfill for retaining walls (abutment and wing walls), fill placement and compaction will ultimately depend on the wall design.

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 6 October 2, 2012

4.3 EXCAVATION

Various excavations may be required. The extent and location of excavation will depend on roadway alignment, but some excavation of earth, rubble fill and hard rock is likely. Nearly any significant excavation will require temporary shoring to retain the existing roadway as sloping is likely impractical given the site topography. Most excavation will be more or less confined due to site access considerations.

Excavation can frequently be classified into earth, hard soils/rippable rock, and hard rock. Earth excavation is generally considered soils with SPT N-values of 25 bpf or less and can be accomplished using most earthmoving equipment with little limitation. Harder soils and rubble fill typically require ripping with large trackhoes or single tooth rippers pulled by heavy tractors to loosen the material prior to excavation. Highly fractured rock can sometimes be excavated with heavy trackhoes where joint patterns are favorably oriented.

In confined excavations, partially weathered rock (PWR) and fractured rock may require use of hydraulic hammers (hoe-rams) or blasting to loosen prior to removal. Sound, massive rock typically requires blasting for removal. Hydraulic hammers are unlikely to be effective in removing sound, massive rock. Blasting costs are relatively high, so attempts should be made to remove rock using other methods prior to resorting to blasting, and blast rock quantities should be determined using surveying methods for accuracy. Drilling and blasting rock through soil and PWR makes quantity determination difficult and also increases confinement of the rock. Rock should be exposed by removing all overburden using ripping or other techniques. Blast mats or loose soils should then be placed over the rock surface to limit flying rock and contain the blast. Blasting is not recommended for creating rock sockets for piers since blasting will degrade rock around the socket.

4.4 BRIDGE FOUNDATIONS

The recovery and RQD percentages obtained during coring for this exploration indicate that the bedrock is severely weathered and highly fractured and very soft to moderately hard. Therefore, we anticipate drilled piers/shafts will be required as the deep foundation alternative for the bridge foundations.

4.4.1 Drilled Shaft Recommendations

Drilled shafts should extend beyond any rock lenses and bear on less fractured, more competent rock. The actual bearing capacity available will depend on the quality of rock encountered at each location. We anticipate a bearing capacity of 20 ksf would be reasonable for design, although higher allowable values of 40+ ksf would be available if piers were able to consistently penetrate the upper

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 7 October 2, 2012 layer of fractured rock. This higher allowable bearing pressure may require extensive removal of poor quality rock to reach the higher quality rock required.

Soil test boring auger refusal typically is assumed to correspond to auger refusal with LLDH drilling equipment used to install piers. Actual rock auger refusal (LLDH refusal) in fractured rock, such as that observed at this site, may be deeper than expected based on the borings if the joints and the fracture pattern of the rock is compatible with the augering teeth and rotation, or shallower if the pattern is adverse. Additionally, drilled pier machines that have a much higher down pressure and torque are locally available that would likely penetrate below the refusal elevations in the soil test borings into more competent rock. Therefore, rock auger refusal levels as indicated on the Soil Test

Boring Records, should be considered approximate.

Shaft friction and concrete bond to rock may be considered in addition to end bearing to achieve the design capacity. An allowable shaft friction of 2 ksf in rock can be used for design; however, end bearing should provide at least 75 percent of the total capacity. The top 5 feet of piers should not be included in determining shaft friction. The actual soil and rock conditions should be observed and evaluated during shaft construction to either confirm or modify the design parameters based on specific materials encountered.

Lateral pier capacity will depend on column loads, pier diameter and length, allowable head deflection, and soil parameters surrounding the piers. We can provide recommendations of lateral pier capacity as the necessary design information becomes available.

Shaft diameters should not be less than 24 inches to facilitate cleaning and observation of the pier bottom. We recommend that pier spacing be no closer than three pier diameters. Limiting the number of shaft diameters generally results in a lower construction cost due to less equipment being mobilized to the site and less time changing out augers and casings.

We recommend the use of drilling equipment that has the capacity to produce a continuous torque of at least 1,000,000 inch-pounds and a downward force of at least 50,000 pounds (Hughes LLDH). This equipment is generally capable of reaching our auger refusal depth as indicated on the attached Soil

Test Boring Records. Additionally, we recommend that rock be defined as material which cannot be penetrated faster than 2 feet per hour (measured over a 15-minute minimum time frame) using a rock auger with hardened steel teeth (Kennametal bits or equivalent) and the specified drilling equipment.

The purpose of this definition is to quantify isolated rock lenses in the soil matrix which require removal to reach an acceptable bearing level. The construction of drilled piers should be performed in accordance with the methods outlined in the manual "Drilled Shafts: Construction Procedures and

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 8 October 2, 2012

LRFD Design Methods" FHWA Publication No. FHWA-NHI-10-016. In addition, we recommend that piers be designed in accordance with “AASHTO LRFD Bridge Construction Specifications.

A geotechnical engineer using available technology should observe the pier bearing surface to determine if acceptable bearing material is present. Our observation may detect variations in subsurface conditions (fractured or sound rock) which necessitate redesign the extension of the pier into rock. The extension of pier shafts below rock auger refusal (LLDH refusal) levels typically requires special excavation, which may include coring, pneumatic hammers, or blasting. We recommend that a unit price for shaft excavation beyond rock auger refusal (LLDH refusal) and hand rock excavation per cubic yard be included in the project bid documents.

4.5 GROUND WATER MANAGEMENT

Portions of the bridge foundation will bear below the stream bed level and dewatering of the foundation excavations will be required for these portions construction. The stream or portions the stream will likely require diverting and/or “pumping around” and foundation excavations may require protection with diversion/coffer dams.

It is anticipated groundwater control can be provided using sumps and cutoff trenches outside the perimeters of foundation excavations. We recommend the groundwater levels be lowered and maintained at a depth of at least one foot below foundation excavation bottoms during construction.

4.6 RETAINING WALL RECOMMENDATIONS

To build the proposed roadway realignment through the Bald River Falls area, it will be necessary to construct a retaining wall along the outside edge of the desired shoulder, up to about 25 feet horizontally from the existing pavement edge. The wall will need to bear in or on sound rock and will need to retain existing soils and/or new fill placed to support the roadway. The wall will need to accommodate drainage beneath the roadway and through the wall.

Retaining wall options could include mechanically stabilized earth (MSE) walls or concrete cantilever or gravity walls. Mechanically stabilized earth walls are a type of gravity structure using facing elements (typically concrete blocks or panels) and reinforcement in a backfill zone extending behind the wall. The reinforcement is typically steel strips or plastic geogrids. The reinforced backfill zone acts as a gravity structure to resist overturning and sliding. These walls should also bear on the rock and may consider a friction coefficient of 0.4 if soil backfill is used or 0.5 if select granular backfill is used.

Concrete cantilever walls resist lateral soil pressures by the weight of soil over the heel of the wall and friction between the wall and foundation material. Gravity walls resist these forces by the weight of

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 9 October 2, 2012 the wall. At this site, either type of wall could be modified to employ rock anchors to enhance overturning and/or sliding resistance. Walls should be founded on rock or PWR, which should be leveled. Since the rock surface will likely be irregular due to blasting, an allowable friction coefficient between the concrete and rock of 0.5 may be considered.

For wall construction, a horizontal bench could be excavated below the roadway and into the rock surface. The bench would need to be wide enough for equipment access, probably a minimum of 8 feet. The upslope side of the bench would need to be shored temporarily. A top down shoring method, such as soil nails (see below), would likely be effective for this purpose. A retaining wall would be constructed on the bench and backfilled to support the proposed roadway. Concrete walls could use rock anchors to enhance overturning resistance. The soil nail shoring of the excavation would tend to reduce lateral forces on the wall.

Soil nails are steel tension members, typically reinforcing steel, grouted into holes drilled at a slight angle below horizontal into the face of an excavation as it advances. Soil nails reinforce a zone behind the face such that the zone acts together to resist sliding and overturning. A typical spacing is

4 feet on center in each direction. The face is typically covered with welded wire mesh and covered with shotcrete, although other facing options are possible.

Retaining walls that are unrestrained and free to bend or rotate outward to mobilize soil strength may consider the active earth pressure coefficient (Ka). However, we expect walls for this project to be restrained by anchors so that little movement may occur. For these, the at-rest earth pressure coefficient (Ko) should be considered. We recommend all walls be provided with drainage to prevent buildup of hydrostatic pressures. Anchorage and the geometry of most walls will not provide significant passive pressure at the toe, which is developed if the wall can slide away from the backfill.

Cantilever and Gravity Walls, including MSE walls, typically consider a triangular pressure distribution.

We recommend the following parameters be used for development of lateral pressures on walls:

Material Friction Angle () degrees

Unit Weight () pcf

Ka Ko

Compacted Soil Fill 26 120 0.39 0.56 Graded Aggregate 38 145 0.24 0.40

#57 Stone 40 105 0.22 0.36

4.7 DRAINAGE

Drainage should be incorporated into whatever retaining wall types are used. Drainage should allow groundwater entering from the retained soils to exit the wall without either transporting soils through

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 10 October 2, 2012 the wall or saturating the reinforced backfill zone of MSE walls. If soil backfill is used, a vertical chimney drain should be incorporated between wall and backfill or between the reinforced backfill zone and retained soil on MSE walls. This chimney drain can use filtered gravel or prefabricated drainage composites connected to a horizontal collector pipe with periodic pipes extending to the face of the wall. Select granular backfill should provide acceptable drainage with periodic weepholes in concrete walls. If open graded backfill (#57 stone) is used, a filter of GAB or filter geotextile should be incorporated between the stone and retained earth to avoid migration of soil fines in the stone.

Surface drainage on the wall should not be allowed to enter the subsurface drains. To this end, select granular backfill should be covered with at least 2 feet of relatively low-permeability soil fill. Filtration may be required to prevent this fill from washing into gravel backfill. The fill surface should be sloped to drain and thereby limit infiltration.

Surface water should be collected behind the top of the wall and into drop inlets to dissipate energy and prevent flow over the face of the wall. Outlets should be placed to avoid erosion near the base of the wall. Similarly, surface water flowing toward the road should be collected in a ditch along the other side of the road and periodically transferred across the road using piping.

4.8 ROCK ANCHORS

Rock anchors are tensile members, typically high strength steel bars or tendons installed in holes drilled through the soil overburden and into the rock. An ultimate value of 10 ksf on the bond area can typically be achieved in the rock. Anchors typically have a free length sleeved through the soil. The anchors are typically pre-tensioned with select anchors proof tested. Where anchors are installed before walls are fully backfilled, a steel pipe section is typically installed around the anchor tendons to the rock to provide compressive resistance. Such anchors may be re-tensioned to increasing loads after backfill is placed.

4.9 PERMANENT AND TEMPORARY SLOPES

For safety, construction excavations should be either sloped or braced in accordance with OSHA regulations described in the manual for Occupational Safety and Health Standards – Excavations (29

CFR Part 1926). Permanent slopes should be constructed no steeper than 3 horizontal to 1 vertical

(3H:1V) to allow maintenance of vegetative cover and no steeper than 2H:1V in any case, based on our experience with similar subsurface conditions.

During construction, temporary slopes should be regularly inspected for signs of movement or unsafe conditions. Soil slopes should be covered for protection from rain and surface run-off should be diverted away from the slopes. A protective cover of grass or other vegetation should be established on permanent slopes as soon as possible to aid in erosion protection.

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 11 October 2, 2012

4.10 ADDITIONAL EXPLORATION

Rock lenses and highly varying rock qualities were observed during this exploration. It may be beneficial to further explore the rock quality to aid in determining factors such as anticipated footing elevations, difficulty of rock excavation, and the accuracy of the refusal elevations shown on the Soil

Test Boring Records.

More detailed geotechnical study(ies) may include:

1. A site reconnaissance and rock mapping of the slope faces above and below the roadway, and in the vicinity of bent foundations.

2. Rock coring to at least 10 feet below the river bed or 50 feet with a downhole televiewer to map orientation of joints.

3. Seismic refraction lines along the outside edge of the new road alignment on the steep slope.

4. Shear Wave Velocity profiles or Spectral Analysis of Surface Waves (SASW) to provide characterization of the rock beneath the alignment to potential foundation bearing depths.

5.0 QUALIFICATIONS OF RECOMMENDATIONS

Our evaluation of foundation design and construction conditions has been based on our understanding of the site and project information and the data obtained during our field exploration.

The general subsurface conditions used were based on interpolation of the subsurface data between the borings. The nature and extent of variations between the borings may not become evident until the course of construction. If such variations then appear evident, it will be necessary to re-evaluate the recommendations of this report after on-site observations of the conditions.

Regardless of the thoroughness of a geotechnical exploration, there is the possibility that conditions between borings will differ from those at the boring locations, that conditions are not as anticipated by the designers, or that the construction process has altered the soil conditions. Therefore, experienced geotechnical engineers from AMEC should evaluate earthwork and foundation construction to evaluate that the conditions anticipated in design actually exist.

Our professional services have been performed, our findings derived, and our recommendations prepared in accordance with generally accepted geotechnical engineering principles and practices.

This warranty is in lieu of all other warranties either expressed or implied. This company is not responsible for the conclusions, opinions, or recommendations of others based on these data. The

Project No. 6163-12-0182.03, Bald River Falls Bridge, Tellico River Road, Monroe County, Tennessee 12 October 2, 2012 assessment of site environmental conditions or the detection of pollutants in the soil or groundwater was beyond the scope of this exploration.

APPENDIX

Figure 1. Boring Location Plan

Figure 2. Cross Section

Field Testing Procedures

Key to Boring Symbols

Soil Test Boring Records (4)

Photographic Records (7)

Laboratory Test Results

ASFE Information on Geotechnical Reports

FIELD EXPLORATORY PROCEDURES

Field Operations: The general field procedures employed by AMEC Environment &

Infrastructure, Inc. (AMEC) are summarized in ASTM D 420, which is entitled

“Investigating and Sampling Soils and Rocks for Engineering Purposes.” This recommended practice lists recognized methods for determining soil and rock distribution and groundwater conditions. These methods include geophysical and in situ methods as well as borings.

Borings are drilled to obtain subsurface samples using one of several alternate techniques depending upon the subsurface conditions. These techniques are:

a. Continuous 2-1/2 or 3-1/4 inch I.D. hollow stem augers;

b. Wash borings using roller cone or drag bits (mud or water);

c. Continuous flight augers (ASTM D 1425).

These drilling methods are not capable of penetrating through material designated as

“refusal materials.” Refusal, thus indicated, may result from hard cemented soil, soft weathered rock, coarse gravel or boulders, thin rock seams, or the upper surface of sound continuous rock. Core drilling procedures are required to determine the character and continuity of refusal materials.

The subsurface conditions encountered during drilling are reported on a field test boring record by the chief driller. The record contains information concerning the boring method, samples attempted and recovered, indications of the presence of various materials such as coarse gravel, cobbles, etc., and observations between samples.

Therefore, these boring records contain both factual and interpretive information. The field boring records are on file in our office.

The soil and rock samples and the field boring records are reviewed by a geotechnical engineer. The engineer classifies the soils in general accordance with the procedures outlined in ASTM D 2488 and prepares the final boring records that are the basis for all evaluations and recommendations.

The final boring records represent our interpretation of the contents of the field records based on the results of the engineering examinations and tests of the field samples.

These records depict subsurface conditions at the specific locations and at the particular time when drilled. Soil conditions at other locations may differ from conditions occurring at these boring locations. Also, the passage of time may result in a change in the subsurface soil and groundwater conditions at these boring locations. The lines designating the interface between soil or refusal materials on the records and on profiles represent approximate boundaries. The transition between materials may be gradual.

The final boring records are included with this report.

The detailed data collection methods used during this study are discussed on the following pages.

Soil Test Borings: Soil test borings were made at the site at approximate locations shown on the attached Boring Location Plan. Soil sampling and penetration testing were performed in general accordance with ASTM D 1586.

Each boring was made by mechanically twisting a hollow-stem steel auger into the soil.

At regular intervals, the drilling tools were removed and soil samples obtained with a standard 1.4-inch I.D., 2-inch O.D., split tube sampler. The sampler was first seated

6 inches to penetrate loose cuttings, then driven an additional foot with blows of a

140-pound hammer falling 30 inches. The number of hammer blows required to drive the sampler the final foot was recorded and is designated the “penetration resistance.” The penetration resistance, when properly evaluated, is an index to the soil strength and foundation supporting capability.

Representative portions of the soil samples, thus obtained, were placed in glass jars and transported to the laboratory. In the laboratory, the samples were examined to evaluate the driller's field classifications. Test boring records are attached which graphically show the soil descriptions and penetration resistances.

Water Level Readings: Water table readings are normally taken in conjunction with borings and are recorded on the “Test Boring Records.” These readings indicate the approximate location of the hydrostatic water table at the time of our field investigation.

Where impervious soils are encountered (clayey soils) the amount of water seepage into the boring is small, and it is generally not possible to establish the location of the hydrostatic water table through water level readings. The groundwater table may also depend on the amount of precipitation at the site during a particular period. Fluctuations in the water table should be expected with variations in precipitation, surface run-off, evaporation and other factors.

The time of boring water level reported on the boring records is determined by field crews as the drilling tools are advanced. The time of boring water level is detected by changes in the drilling rate, soil samples obtained, etc. The readings are taken by dropping a weighted line down the boring or using an electrical probe to detect the water level surface.

Rock Coring: Core drilling procedures were utilized to determine the character and continuity of materials below the soil drilling refusal level. The core drilling procedure is performed in general accordance with ASTM designation D-2113-70. Initially, casing is set though the overburden soils to keep the hole from collapsing. Refusal materials are then cored with a diamond-studded bit fastened to the end of a hollow double-tube core barrel. This device is rotated at high speeds and is capable of cutting the hardest rock.

The cuttings are brought to the surface by circulating water. Rock core samples of the materials penetrated are protected and retained in a swivel-mounted inner tube. Upon completion of the drill run, the core barrel is brought to the surface and the samples are removed and placed in core boxes. The samples are then returned to our laboratory where the rock is identified and the “recovery” and “rock quality designation” (RQD) are determined.

Rock Hardness descriptions are listed below:

Rock Hardness Descriptions

Very Hard Rock core rings and can be made to spark when struck with a hammer

Hard Rock core rings when struck with a hammer

Moderately Hard Thin edges of rock core cannot be broken with fingers

Soft Thin edges of rock core can be broken with fingers

Very Soft Rock core crumbles when handled

The “recovery” is the ratio of the sample length to the length drilled, expressed as a percent. The “rock quality designation” (RQD) is the percent of recovered rock sample in segments four or more inches long compared to the total length of the run. This designation is generally applied only to samples of NX size or larger and to samples described as moderately hard or harder. The percent recovery and RQD are related to rock soundness and continuity. The NX size designates a bit which obtains core samples 2-1/8 inches in diameter.

GROUP

SYMBOLS

TYPICAL NAMES

GROUP

SYMBOLS

Dense

Undisturbed Sample 1.5-2.0 = Recovered (ft) / Pushed (ft)

31 - 50

Over 50

Very Loose

UNDISTURBED SAMPLE ATTEMPT

Reference: The Unified Soil Classification System, Corps of Engineers, U.S. Army Technical Memorandum No. 3-357, Vol. 1, March, 1953 (Revised April, 1960)

0 - 2

3 - 4

Very Stiff

Over 50

Boulders

U.S. STANDARD SIEVE SIZE

GRAVEL

11 - 20

DOLOMITE

TOPSOIL

ASPHALT

FILL

KEY TO SYMBOLS AND

DESCRIPTIONS

Stiff

Medium

3/4"

Coarse

SANDSTONE

SHALE

RESIDUUM - Stiff to very hard

RESIDUUM - Soft to firm

Cobbles

CONCRETE

No.40

Very Dense

No.10 No.4

Water Table at time of drilling

Very Hard

21 - 30

Firm

12"

Split Spoon Sample

Loose

No. of BlowsRelative Density

5 - 10

Fine

Consistency

Fine

SUBSOIL

3"

ALLUVIUM

COLLUVIUM

LIMESTONE

0 - 4

5 - 8

No Sample

Rotary Drill

AUGER BORING

BOUNDARY CLASSIFICATIONS: Soils possessing characteristics of two groups are designated by combinations of group symbols.

Crandall Sampler

Pressure Meter

9 - 15

SILTSTONE

Correlation of Penetration Resistance with Relative Density and Consistency

SILT & CLAY

31 - 50

16 - 30

Very Soft

Soft

Firm

Auger Cuttings

Dilatometer

No Recovery

Water Table after 24 hours

Rock Core 60-100 = RQD / Recovery

SAND & GRAVEL

No. of Blows

Hard

No.200

Coarse

SILT OR CLAY

SAND

Very Firm

TYPICAL NAMES

LIMESTONE/SHALE - Limestone with shale interbeds

COAL

AMEC Environment & Infrastructure, Inc.

9725 Cogdill Road

Knoxville, Tennessee 37931 865-671-6774 Fax: 865-671-6254

ASPHALT (0.2')

Firm to very stiff, dry, yellow-brown, silt with gravel - FILL Note: sample 2 SPT value elevated by rock at bottom of sample interval)

Very hard, dry, dark brown, weathered sandstone - POSSIBLE

FILL

Auger Refusal at 4.5'. Began NQ coring at 4.5'.

SANDSTONE: gray to dark gray, medium strong, thickly bedded, moderately weathered, locally clayey (graywacke).

Fractured at average spacing of 0.4'; fractures at 30°.

SANDSTONE: gray to dark gray where fresh, medium strong to strong, thickly bedded, moderately weathered to fresh, locally clayey and pitted. Weathering more developed from 7.5' to 9.5'

SANDSTONE: gray to dark gray, medium strong, thickly bedded. Fresh to slightly weathered at fractures, fine grained with local coarse sections, locally pitted. Weathered joints are dark brown to dark yellow brown. Fractured zones at depths of 11.5' to 11.6' and 13.4' to 13.6'.

SANDSTONE: gray to dark gray where fresh to dark brown to dark yellow brown where weathering more developed, medium strong to weak from depth of 19.4' to 20.2' where core reduced to rubble, thick bedded, fresh to moderately weathered (weathered predominately from depth of 17.6' to 20.6'), fine-grained. Fractured from depth of 17.6' to 20.6'.

SANDSTONE: dark gray to very dark gray, weathered zones / joints are dark yellowish brown, medium strong to weak, thickly bedded, fresh to moderately weathered locally and at joints, fine to medium grained. Trace thin irregular, subhorizontal shale / slate. Fractured / jointed throughout with two predominate orientations at 60° to 80° and 10° to 15°.

SANDSTONE: dark gray to black, weathered zones / joints are dark yellow brown, few thin clayey zones, medium strong to weak, thick to medium bedded, fresh to moderately weathered locally and at joints, fine to medium grained.

Jointed throughout, orthogonal joint sets at 40° to 60° and 15° to 30°.

SANDSTONE: dark gray to very dark gray. Weathered zones / joints are dark yellow brown, medium strong to weak, thickly bedded, fresh to moderately weathered locally and at joints, fine to medium grained. Jointed throughout with orthogonal joint sets at 15° to 40° and 50° to 70°.

Coring terminated at 35.1'

2-2-4

2-3-24

50/0.4

95-100

90-100

87-99

46-100

0-100

16-100

53-96

SPT-1

BULK-1

SPT-2

SPT-3

RC-1

RC-2

RC-3

RC-4

RC-5

RC-6

RC-7

REMARKS:

SEE KEY SYMBOL SHEET FOR EXPLANATION OF

SYMBOLS AND ABBREVIATIONS BELOW.

1s t 6

2n d

6"

3r d

6"

SOIL TEST BORING RECORD

FINES (%)

SPT (bpf)

T Y P E

1372.0

1367.0

1362.0

1357.0

1352.0

1347.0

1342.0

1337.0

1332.0

1327.0 0 10 20 30 40 50 60 70 80 90 100

DRILLED:

I D E N T

SAMPLESE

L E V

(ft)

SOIL CLASSIFICATION

AND REMARKS

10 20 30 40 50 60 70 80 90 100

PL (%) NM (%) LL (%)

N-COUNT

L E G E N D

Standard Penetration resistance testing performed using an automatic hammer. No groundwater encountered while augering. No coring water losses. Water at a depth of about 3.0' in boring after coring.

BORING NO.: B-1

D E P T H

(ft)

THIS RECORD IS A REASONABLE INTERPRETATION OF

SUBSURFACE CONDITIONS AT THE EXPLORATION

LOCATION. SUBSURFACE CONDITIONS AT OTHER

LOCATIONS AND AT OTHER TIMES MAY DIFFER.

INTERFACES BEWEEN STRATA ARE APPROXIMATE.

TRANSITIONS BETWEEN STRATA MAY BE GRADUAL.

PROJECT:

PROJ. NO.:

Driller : Tri-State

Logged By: JCM

Checked By: TL

Ball River Falls Bridge Replacement

July 9, 2012

6163-12-0182.03

S O

IL

2_

.G P

J L

A W

_G

IB

B .G

D T

/2

7/

ASPHALT (0.1')

Dense to medium dense, dry, very dark gray, brown, and light yellow brown, gravel with silt and trace of clay in lower portion of interval - FILL

Auger Refusal at 3.2'. Began NQ coring at 3.2'.

Sandstone rubble FILL (recovered core consists largely of rubble with 30% in intact pieces from 1 to 3 inches in length).

SILTSTONE: dark gray to very dark gray where relatively fresh to brown where weathering is more developed and on most fractures, fine grained with trace of sand, extremely weak to medium strong, thickly bedded, completely weathered to fresh, attitude indeterminate, jointed throughout, most joints subvertical 10° to 15° and 25° to 35°.

Coring terminated at 36.3'

22-21-14

6-8-7

0-34

0-19

0-22

0-50

0-94

0-100

24-98

SPT-1

BULK-1

SPT-2

RC-1

RC-2

RC-3

RC-4

RC-5

RC-6

RC-7

REMARKS:

SEE KEY SYMBOL SHEET FOR EXPLANATION OF

SYMBOLS AND ABBREVIATIONS BELOW.

1s t 6

2n d

6"

3r d

6"

SOIL TEST BORING RECORD

FINES (%)

SPT (bpf)

T Y P E

1371.0

1366.0

1361.0

1356.0

1351.0

1346.0

1341.0

1336.0

1331.0

1326.0 0 10 20 30 40 50 60 70 80 90 100

DRILLED:

I D E N T

SAMPLESE

L E V

(ft)

SOIL CLASSIFICATION

AND REMARKS

10 20 30 40 50 60 70 80 90 100

PL (%) NM (%) LL (%)

N-COUNT

L E G E N D

Standard Penetration resistance testing performed using an automatic hammer. No groundwater encountered at time of exploration prior to coring. Lost 100% of coring water return with 2nd core run.

BORING NO.: B-2

D E P T H

(ft)

THIS RECORD IS A REASONABLE INTERPRETATION OF

SUBSURFACE CONDITIONS AT THE EXPLORATION

LOCATION. SUBSURFACE CONDITIONS AT OTHER

LOCATIONS AND AT OTHER TIMES MAY DIFFER.

INTERFACES BEWEEN STRATA ARE APPROXIMATE.

TRANSITIONS BETWEEN STRATA MAY BE GRADUAL.

PROJECT:

PROJ. NO.:

Driller : Tri-State

Logged By: JCM

Checked By: TL

Ball River Falls Bridge Replacement

July 10, 2012

6163-12-0182.03

S O

IL

2_

.G P

J L

A W

_G

IB

B .G

D T

/2

ASPHALT (0.1')

Dense to medium dense, dry, light gray, brown, light brown, and yellow brown, gravel with silt and sand - FILL

Auger Refusal at 6.0'. Began NQ coring at 6.0' Sandstone boulder / rubble (alternating between hard and soft materials) - FILL

SANDSTONE: fine to medium grained, locally grades to siltstone, gray to very dark gray to dark yellow brown at weathered joints, medium strong, thickly bedded slightly to moderately weathered from depth of about 24.4' to 25.3' at fracture zone, remainder fresh.

SANDSTONE: fine to medium grained, local discontinuous siltstone, gray to very dark gray, medium strong, thick bedded, fresh.

SANDSTONE: fine to medium grained, gray to very dark gray, medium strong, thick bedded, fresh. From depth of about 33.6' to 33.6' fracture zone.

SANDSTONE: fine to coarse grained, grades locally to sandy siltstone, gray to very dark gray, medium strong, thickly bedded, fresh.

Coring terminated at 40.9'

20-32-33

7-16-12

5-9-12

9-24

0-22

0-28

21-62

67-98

90-100

73-95

SPT-1

BULK-1

SPT-2

SPT-3

RC-1

RC-2

RC-3

RC-4

RC-5

RC-6

RC-7

REMARKS:

SEE KEY SYMBOL SHEET FOR EXPLANATION OF

SYMBOLS AND ABBREVIATIONS BELOW.

1s t 6

2n d

6"

3r d

6"

SOIL TEST BORING RECORD

FINES (%)

SPT (bpf)

T Y P E

1371.0

1366.0

1361.0

1356.0

1351.0

1346.0

1341.0

1336.0

1331.0

1326.0 0 10 20 30 40 50 60 70 80 90 100

DRILLED:

I D E N T

SAMPLESE

L E V

(ft)

SOIL CLASSIFICATION

AND REMARKS

10 20 30 40 50 60 70 80 90 100

PL (%) NM (%) LL (%)

N-COUNT

L E G E N D

Standard Penetration resistance testing performed using an automatic hammer. Lost 100% of coring water return with 2nd core run. Water at depth of about 28.2' in boring after coring.

BORING NO.: B-3

D E P T H

(ft)

THIS RECORD IS A REASONABLE INTERPRETATION OF

SUBSURFACE CONDITIONS AT THE EXPLORATION

LOCATION. SUBSURFACE CONDITIONS AT OTHER

LOCATIONS AND AT OTHER TIMES MAY DIFFER.

INTERFACES BEWEEN STRATA ARE APPROXIMATE.

TRANSITIONS BETWEEN STRATA MAY BE GRADUAL.

PROJECT:

PROJ. NO.:

Driller : Tri-State

Logged By: JCM

Checked By: TL

Ball River Falls Bridge Replacement

July 11, 2012

6163-12-0182.03

S O

IL

2_

.G P

J L

A W

_G

IB

B .G

D T

/2

ASPHALT (0.3')

Medium dense to dense, dry, dark yellow brown to gray gravel with silt and trace of sand - FILL

Very hard weathered rock - RESIDUUM Auger Refusal at 4.5'. Began NQ coring at 4.5'.

SANDSTONE: fine to coarse grained, gray to dark gray to brown to dark brown where more weathered, medium strong, thick bedded, slightly weathered to fresh. Jointed throughout with joints at 15° to 20° at average spacing of about 0.3'. From depth of about 4.5' to 5.0' highly weathered and fractured.

From depth of 9.0' to 9.2'. Highly weathered. From depth of 9.2' to 9.8' higher clay content, moderately weathered, heavy iron staining on joints.

SANDSTONE: fine to coarse grained, gray to dark gray, locally brown to dark brown where weathered, medium strong to locally weak where weathered, thickly bedded, fresh to locally moderately weathered. Jointed throughout at average spacing of approximately 0.4' at 10° to 20°.

SANDSTONE: coarse grained, brown to dark gray, weak to medium strong, thickly bedded, slightly weathered to locally moderately / high weathered. Jointed throughout with joints at average spacing of approximately 0.3', 5° to 20°.

SANDSTONE: coarse grained, bluish gray to dark bluish gray, moderately strong, thick bedded, fresh to locally slightly weathered at joints. Weathered areas are dark yellow brown.

Coring terminated at 25.9'

15-10-7

4-14-17

50/0.2'

48-94

27-100

58-98

12-86

86-98

SPT-1

BULK-1

SPT-2

SPT-3

RC-1

RC-2

RC-3

RC-4

RC-5

REMARKS:

SEE KEY SYMBOL SHEET FOR EXPLANATION OF

SYMBOLS AND ABBREVIATIONS BELOW.

1s t 6

2n d

6"

3r d

6"

SOIL TEST BORING RECORD

FINES (%)

SPT (bpf)

T Y P E

1372.0

1367.0

1362.0

1357.0

1352.