excellence. innovation. service. value. since 1954. fileshannon &wilson. inc. geotl;chnic:al and...

SHANNON &WILSON. INC.

GEOTl;CHNIC:AL AND ENVIRONMENTAL CONSULTANTS

Geotechnical Report Black Creek Bridge No. 7 Replacement

Grays Harbor County, Washington

September 16, 2009

Excellence. Innovation. Service. Value.

Since 1954.

Submitted To: H.W. Lochner, Inc.

Attn: Al King 4224 61

h Avenue SE, Building 2C Lacey, Washington 98503

By: Shannon & Wilson, Inc.

400 N 34th Street, Suite 100 Seattle, Washington 98103

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SHANNON &WILSON, INC.

TABLE OF CONTENTS

Page

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

2.0 SITE AND PROJECT DESCRIPTION ................................................................................ 1

3.0 FIELD EXPLORATIONS .................................................................................................... 1

4.0 GEOTECHNICAL LABORATORY TESTING .................................................................. 2

5.0 GEOLOGY AND SUBSURFACE CONDITIONS .............................................................. 2 5.1 Site Geology ............................................................................................................... 2 5.2 Subsurface Conditions ............................................................................................... 2 5.3 Observed Groundwater Conditions ....................................................... , .................... 2

6.0 SEISMIC DESIGN RECOMMENDATIONS ...................................................................... 3 6.1 Ground Motions ........................................................................................................ 3 6.2 Earthquake-induced Geologic Hazards ..................................................................... 3

6.2.1 Liquefaction ................................................................................................ 3 6.2.2 Lateral Spreading ........................................................................................ 4 6.2.3 Liquefaction-induced Settlement ................................................................ 4 L . c. • M'. . 4

1que1actton 1ttgahon ...................................... :············· ....................................... . 6.3

7.0 ENGINEERING ANALYSIS AND RECOMMENDATIONS ............................................ 5 7.1 General ..................................................... ~ ................................................................ 5 7.2 Driven Pile Foundation Design ................................................................................. 5 7.3 Lateral Earth Pressures .............................................................................................. 6 7.4 Lateral Resistance ............................................................................................... , ...... 7 7 .5 Approach Fill Embankment ....................................................................................... 7 7.6 Fill Embankment Subgrade Settlement.. .................................................................... 7

8.0 EARTHWORK AND CONSTRUCTION CONSIDERATIONS ......................................... 8 8.1 Demolition ................................................................................................................ 8 8.2 Site Stripping and Preparation .................................................................................. 8 8.3 Fill Placement and Compaction ................................................................................ 8 8.4 Temporary Cut Slopes ............................................................................................... 9 8.5 Dewatering .............................................................................................................. 10 8.6 Pile Installation ....................................................................................................... 10

8.6.1 Pile-driving Equipment ............................................................................. 10 8.6.2 Wave Equation Analysis ........................................................................... 11 8.6.3 Monitoring Pile-driving ............................................................................ 11

8. 7 Wet Weather and Wet Condition Considerations ................................................... 12

9.0 ADDITIONAL SERVICES ................................................................................................ 13

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TABLE OF CONTENTS (cont.) SHANNON &WILSON, INC.

Page

10.0 LIMITATIONS .................................................................................................................... 13

11.0 REFERENCES ..................................................................................................................... 15

TABLES

1 Recommended Parameters for Design Response Spectra Construction 2 Recommended Parameters for Development of P-Y Curves Using LPILE

FIGURES

1 Vicinity Map 2 Site and Exploration Plan 3 Estimated Axial Pile Resistance of 16-in-dia., Yi-inch Wall, Steel Pipe Pile,

Driven Closed-ended 4 Estimated Axial Pile Resistance of 18-in-dia., Yi-inch Wall, Steel Pipe Pile,

Driven Closed-ended 5 Wave Equation Analysis, 16-inch-dia., Yi-inch Wall Steel Pipe Pile, Driven with

Delmag D 22-23 6 Wave Equation Analysis, 18-inch-dia., Yi-inch Wall, Steel Pipe Pile, Driven with

Delmag D 22-23

APPENDICES

A Subsurface Explorations B Geotechnical Laboratory Test Results C Important Information About Your Geotechnical Report

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SHANNON l WILSON, INC.

GEOTECHNICAL REPORT

BLACK CREEK BRIDGE No. 7 REPLACEMENT

GRAYS HARBOR COUNTY, WASIDNGTON

1.0 INTRODUCTION

This report presents the results of our field explorations, laboratory testing, and geotechnical

engineering studies and recommendations for the proposed replacement bridge Ne . 7 along

Black Creek Road in Grays Harbor County, Washington. Our scope of work inch ded evaluating

the subsurface conditions at the proposed project site, conducting field exploratior sand

laboratory testing, and performing engineering studies for developing recommendations for the design and construction of the new bridge.

Our services were performed in general accordance with the Scope of Work defirn d in

Appendix A of H. W. Lochner' s Consultant Agreement. This agreement was signt d and notice

to proceed was provided by Mr. Robert Munchinski ofH.W. Lochner on June 29, ~009.

2.0 SITE AND PROJECT DESCRIPTION

The project site is located along Black Creek Road, approximately five miles nortl west of

Montesano in Grays Harbor County, Washington. The project site is shown in the Vicinity Map,

Figure 1. The existing bridge is a single-span, one lane bridge over Black Creek. We understand

that the proposed replacement bridge will be an 80-foot-long, single-span, and two lane precast

bridge. The proposed bridge deck will be approximately 3 feet higher than the exi$ting bridge

deck. We understand that a temporary detour bridge will be constructed east of th1e existing

bridge. The existing bridge superstructure, pile foundations and abutments will be demolished.

The Site and Exploration Plan, Figure 2, shows the existing and detour bridge locations.

3.0 FIELD EXPLORATIONS

The subsurface exploration program included drilling one boring ( designated B-1) ~n the

roadway and southeast of the existing bridge. Figure 2 shows the approximate bor ng location.

Boring B-1 was drilled to 58.9 feet below ground surface below ground surface (bhs). The

methods and procedures used for drilling and sampling the explorations are discus~ ed in

Appendix A, Subsurface Explorations. The boring log is presented in Appendix A as Figure A-2.

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4.0 GEOTECHNICAL LABORATORY TESTING

Geotechnical laboratory tests were performed on selected samples retrieved from the boring to

determine basic index and engineering properties of the soils encountered. The geotechnical

laboratory testing performed in the Shannon & Wilson, Inc. laboratory in Seattle, Washington,

included visual classification, water content determinations, grain size distributions, and

Atterberg Limit determinations. Laboratory testing was performed in general accordance with

the ASTM International (ASTM, 2009) standard test procedures. The results of the laboratory

testing were incorporated into the soil descriptions shown on the exploration logs included in

Appendix A. Test procedure descriptions and test result summaries are presented in

Appendix B.

5.0 GEOLOGY AND SUBSURFACE CONDITIONS

5.1 Site Geology

Published geologic maps of the area show that the site is underlain by Miocene age, siltstone

bedrock of the Montesano Formation. This sedimentary bedrock unit consists of siltstone that

was deposited in a marine environment.

5.2 Subsurface Conditions

The soil units encountered in our boring consist of recent alluvium and lacustrine deposits

overlying bedrock. The site soils are described further as follows.

• Alluvium/Lacustrine Deposits - Recent alluvium and lacustrine deposits encountered at the site consist of very soft, clayey, fine sandy silt; very loose to loose, silty, fine to medium sand; medium dense, silty, sandy gravel; and soft, fine sandy, clayey silt to silty clay. These deposits contained zones of wood and were found to a depth of about 50 feet bgs.

• Montesano Formation - Weathered siltstone bedrock was found underlying the alluviumllacustrine deposits. Siltstone is defined as a fine-grained rock composed of silt and clay, with a predominance of silt-sized particles.

5.3 Observed Groundwater Conditions

Groundwater was not observed in the boring during drilling. We interpret groundwater is about

9 feet bgs, which is at the existing creek level. Oxidized soil was observed in the upper 15 feet

of the alluvium encountered in the boring, indicating fluctuation of groundwater level through

the soil. Groundwater conditions can change based on precipitation, site use, and other factors.

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SHANNON l WILSON, INC.

6.0 SEISMIC DESIGN RECOMMENDATIONS

6.1 Ground Motions

We understand that the proposed bridge will be designed in accordance with the 2009 Interim

Revisions of the 2007 4th edition American Association of State Highway and Transportation

Officials (AASHTO) Load and Resistance Factor Design (LRFD) Bridge Design $pecifications

and 2009 1st edition AASHTO Guide Specifications for LRFD Seismic Bridge Design. The

design criteria require that all non-critical transportation structures be designed fo1 no-collapse,

based on a risk level of 7 percent probability of exceedence in 75 years (approximately 1,033-year

recurrence interval). Ground motions for the site were obtained from the U.S. Ge<•logical Survey

(USGS) National Seismic Hazard database (http://earthguake.usgs.gov/hazmapsD oased on the

latitude and longitude of the project site. The USGS completed probabilistic seisnti.ic hazard

analyses for the entire country in November 1996, which were updated and republ shed in 2002

and 2008. The updated USGS maps indicate that for a recurrence interval of 975, ears (5 percent

probability of exceedence in 50 years), the site peak ground acceleration (PGA) fo bedrock conditions is 0.44g.

The site soil response factors are based on determination of the Site Class. Based Dn the

subsurface conditions encountered in our boring, we recommend that the site be classified as Site

Class D. Site Class D corresponds to soil within 100 feet of the ground surface th~ t has an

average shear wave velocity between 600 and 1,200 feet per second or an average Standard

Penetration Test blow count between 15 and 50. We recommend parameters presf1t1ted in Table 1 be used for construction of design response spectra.

We recommend the proposed bridge be assigned to seismic design category D.

6.2 Earthquake-induced Geologic Hazards

Earthquake-induced geologic hazards that may affect the project site include liqueJ action, lateral

spreading, and liquefaction-induced settlement. A discussion of these hazards is p esented below.

6.2.1 Liquefaction

Liquefaction is a phenomenon in which loose deposits ofrelatively clean s~lfld or low

plasticity silt existing below the groundwater level experience a loss of internal sht ar strength

during an earthquake. Liquefaction of loose, saturated, cohesionless soils due to st ismic loading

has been studied over the past 35 years, resulting in methods based on both laborat(>ry and field

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procedures to evalqate liquefaction potential. The most widely used methods are empirical, and

based on correlations between Standard Penetration Test (SPT) resistance (N-value), PGA, and

earthquake magnitude.

We used three methods to evaluate liquefaction potential for the soil layers encountered in boring B-1 :

• Youd et al. (2001) • Seed et al. (2003) • Idriss and Boulanger (2006)

The upper 40 to 45 feet of very loose to medium dense, silty sand in boring B-1 has

factors of safety against liquefaction less than 1.0 for the design ground motion. The results of

the liquefaction analyses have been incorporated into the foundation analyses presented in

Section 7.0.

6.2.2 Lateral Spreading

· The reduction of soil shear strength due to liquefaction combined with even relatively

low static or dynamic shear stresses in a soil may cause significant permanent lateral ground

deformations on gently sloping ground or on level ground adjacent to a "free face" ( e.g., river,

channel, or waterway). Liquefaction of soils at the site may result in permanent lateral ground

displacement or lateral spreading toward the free face at the Black Creek. For the 975-year

ground motions, we estimate a lateral ground displacement of about 15 to 20 feet at a distance

from the edge of the creek of approximately 30 feet.

6.2.3 Liquefaction-induced Settlement

Loose, granular soil susceptible to liquefaction is also susceptible to earthquake-induced

densification. The resulting permanent ground surface settlements may not occur uniformly over

an area, and the differential settlement can be damaging to structures supported on the loose soil.

We estimated liquefaction-induced settlement for the subsurface conditions encountered in the

boring B-1 for the 975-year ground motions. The results indicate that ground settlement ranging

from 1 to 2 feet can occur at the project site.

6.3 Liquefaction Mitigation

Our subsurface explorations findings and analyses indicate the site is underlain by soil with high

liquefaction potential. Mitigation of the effects of liquefaction-induced settlement or lateral soil

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SHANNON M ~LSON. INC.

movement could include ground improvement to prevent or reduce liquefaction or sttrengthen the

soil to resist deformation, or a foundation system and structure that can resist or accpmmodate

the deformations that may occur during seismic event. Ground improvement could include soil

densification using stone columns or increase soil strength using deep soil mixing. Resisting

large lateral loads from liquefaction-induced lateral spreading may be impractical. ... ypically,

drilled shaft foundations can resist larger lateral loads than driven pile foundations. The pile

design recommendations in this report include downdrag loads that could occur if tl e soil

liquefies. The use of driven pile foundation system will reduce settlement of the bri~ge.

However, the approaches could settle as described in Section 6.2.3.

Ground improvement to mitigate liquefaction hazard and/or structural systems that c an resist

liquefaction-induced lateral loads can be costly. The cost can increase substantially when the

depth of liquefaction extends more than 20 feet bgs and if a nonliquefiable crust is i:iresent at

ground surface. Therefore, risk acceptance combined with emergency planning ma·1 be a suitable alternative for this site.

Detailed recommendations for liquefaction mitigation will require additional analys s that are

beyond our scope of services at this time. However, we can be retained to provide sµch recommendations if requested.

7.0 ENGINEERING ANALYSIS AND RECOMMENDATIONS

7.1 General

Based on the results of our subsurface explorations and laboratory tests, we performed

geotechnical engineering studies to develop recommendations for the design and co1~struction of the new replacement bridge foundation system.

It is our opinion that the proposed replacement bridge could be supported on driven piles. Our

geotechnical recommendations for using pile foundation systems are based on AAS'rHO LRFD

methods and are presented in the following sections.

7.2 Driven Pile Foundation Design

We used an in-house computer program to perform axial capacity analyses for 16- a11d 18-inch

diameter, steel, closed-ended pipe piles. The analyses were performed using soil pru ameters for

the subsurface conditions interpreted from our field explorations and our previous e, perience

with similar deep foundation types and subsurface conditions. Soil parameters were assigned to

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the soil layers to estimate the nominal side resistance and base resistance of the proposed piles.

Results of our axial capacity analyses are presented in Figures 3 and 4 for 16- and 18-inch

diameter steel pipe piles driven closed-ended, respectively.

The axial capacity estimates provided assume that the deep foundations are spaced at least three

pile diameters apart, measured center to center. Based on this assumption, the pile group action

is not considered.

Assuming that the piles are designed and installed in accordance with the recommendations

presented in this report, we estimate the settlements of the driven pipe piles to be about Yi inch,

differential settlement could be approximately half of the estimated total settlement between

abutments.

To analyze the resistance of laterally loaded piles, we recommend use of the computer program

LPILE. The recommended LPILE input parameters are listed in Table 2.

7 .3 Lateral Earth Pressures

The lateral pressures against pile-supported abutment walls depend upon many factors, including

method of backfill placement and degree of compaction, backfill slope, surcharge loads, the type

of backfill soil and/or adjacent native soil, drainage provisions, and whether or not the wall could

yield laterally after or during placement of backfill. If the wall is free to yield at the top an

amount equal to approximately 0.001 times the height of the wall, then active earth pressures

would be mobilized. If movement is not allowed because of stiffhess or resistance of the wall,

the wall should be designed for at-rest earth pressures.

We recommend designing walls that are allowed to deflect laterally or to rotate at the top using

an active lateral pressure equivalent to a fluid unit weight of 35 pounds per cubic foot (pcf)

above the groundwater table. Walls that are not allowed to yield or deflect 0.001 times the wall

height should be designed using an at-rest lateral pressure equivalent to a fluid weight of 55 pcf

above the groundwater table. These pressures assume that the backfill slope is horizontal,

imported structural fill is used as wall backfill, and that proper drainage is provided behind the

walls so there is no buildup of hydrostatic pressures. Backfill should not be placed and

compacted behind a wall until the wall is capable of supporting lateral pressures.

We recommend that a dynamic load increment equal to 9 pounds per square foot per foot for

seismic loading condition. This increment should be applied as a uniform load to the wall. The

seismic load is calculated using Mononobe-Okabe analysis method (Mononobe, 1929; Okabe,

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SHANNON~ WILSON, INC.

1926) with a seismic coefficient equal to one-half the soil PGA of 0.44 for the site. These

pressures assume drained conditions behind the wall and a horizontal backfill surf ace.

7 .4 Lateral Resistance

Lateral loads acting on the structure from earthquake and wind, and other loadingi, may be

resisted by the passive earth pressure against foundation caps and the lateral resistance provided

by the piles. We recommend that passive earth pressure be calculated using an equivalent unit

weight of 200 pcf if the foundation caps are confined by native soft/loose soil, anc 3 50 pcf if

backfilled with compacted imported granular fill. These passive earth pressures it elude a

reduction factor of 1.5 to reduce lateral deflections. The passive earth pressure va ues are based

on the assumptions that the adjacent grade is level and the base of the foundation c aps are above

static groundwater table. We recommend ignoring the passive pressure acting on puried

structures within 2 feet of the ground surface.

The magnitude of lateral resistance developed by a deep foundation depends on th~ subsurface

conditions encountered, the type of deep foundation, spacing, and the moment cai: acity at the

pile cap connection. In our opinion, the frictional sliding resistance at the base of he pile

foundation cap should be ignored, because a deep foundation-supported structure !nay not

transmit load directly to the soil beneath the cap.

7.5 Approach Fill Embankment

We understand that the proposed approach fill will be on the order of 3 feet thick. For

permanent embankment constructed using imported granular material, the slope sl~ould not

exceed 1.5 Horizontal to 1 Vertical (l.5H:1V). If the fills are retained, flexible wi 11 systems

such as mechanically stabilized earth or gravity block walls ( ecology block) shoul i be used and

designed to accommodate the anticipated differential settlements along the wall al gnment.

7 .6 Fill Embankment Subgrade Settlement

The load imposed by the new fill placement will likely cause settlement due to the underlying

compressible and loose soil layers. For 3 feet of new embankment fill, we estima1e that a total of

2 to 4 inches could occur. The majority of the settlement should occur within one month after

completion of the fill placement.

We recommend that the fill embankment be constructed to pavement base course elevation at

least one month prior to final paving to reduce potential settlement-induced paven ent cracking.

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8.0 EARTHWORK AND CONSTRUCTION CONSIDERATIONS

8.1 Demolition

Demolition will include removing the existing bridge structures, foundations, asphalt pavement

and base course, and abandoned utilities if present on site. Existing utilities that will interfere

with earthwork activities should be removed and/or relocated prior to construction if present on

site. The base course for the existing pavement could be separated from underlying materials

and stockpiled for use as fill if it meets structural fill requirements as described in Section 8.3 of

this report, but should not be used as based course for new pavement. Demolition debris should

be removed from construction area and disposed of off-site.

8.2 Site Stripping ana Preparation

Site stripping should include removing surface vegetation, organic soil, and other unsuitable

materials. We expect that site stripping could be accomplished using conventional excavating

equipment. The soil from stripping and excavation may be disposed of off-site or used as fill in

landscaped areas. It should not be used as structural fill beneath walls and pavements or as wall

backfill.

After site stripping and preparation activities are complete, the exposed subgrade to receive fill

should be proof-rolled with a fully-loaded dump truck or similar heavy rubber-tired construction

equipment to identify soft, loose or unsuitable areas. The proof-roll should be conducted prior to

placing additional fill. The proof-roll should be observed by a qualified geotechnical engineer or

representative, who should evaluate the suitability of the subgrade and identify areas of yielding.

If loose and/or wet, spongy soil zones are identified by the proof-roll, the soils should be

removed.and replaced with compacted structural fill, or dried or moistened, as required

(including scarifying, mixing, and/or aerating), be reworked, and be adequately compacted to the

density as described in the structural fill requirements in Section 8.3.

Disturbance of subgrade soil due to construction equipment and activities could affect support of

the proposed bridge and roadway. The contractor should take necessary steps to protect the

subgrade from becoming disturbed.

8.3 Fill Placement and Compaction

Structural fill material should be used to backfill footing excavations and for the approach

embankments. Structural fill should be placed in other areas where settlement is to be

minimized. Structural fill should be placed and compacted on a dense and unyielding surface

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that has been evaluated the geotechnical engineer or the engineer's representative. Structural fill

material beneath footings and behind retaining walls should meet the requirement~ of "Gravel

Borrow" in the 2008 Washington State Department of Transportation (WSDOT) ~ tandard

Specifications for Road, Bridge, and Municipal Construction, M 41-1 (WSDOT-SS-08), Section 9-03.14(1) or an approved substitution.

All structural fill should be placed in layers and compacted to at least 95 percent of its modified

Proctor maximum dry density as measured by ASTM D 15 57, and to a dense, unyi el ding

condition. Where more settlement can be tolerated the density requirement may b,e reduced to 92 percent.

In general, the loose lift thickness should not exceed 8 inches for heavy equipment compactors

and 4 inches for hand-operated mechanical compactors. Heavy equipment should Mt be used ·

within 2 feet of the abutment. All compacted surfaces should be sloped to drain to prevent

ponding. Structural fill operations should be observed and evaluated by a represenltative from our firm.

On-site granular soil excavated during construction may be used as a backfill material above the

footing, provided the moisture content of the material is suitable to allow for propetr compaction

and it meets the WSDOT-SS-08 Specification, Section 9-03.14(3) "Structural Bormw."

8.4 Temporary Cut Slopes

Unshored, temporary excavation slopes may be used where planned excavation lin its will not

undermine existing structures, interfere with other construction, or extend beyond I onstruction

limits. The suitable slopes for soil excavation will depend on factors such as: (a) tne presence

and abundance of groundwater; (b) the type and density of the soil; ( c) the depth o excavation;

(d) surcharge loading adjacent to the excavation such as that from excavated mater al, existing

structures, or construction equipment; and ( e) the time of construction. For plannir g purposes,

we recommend that temporary slopes less than 10 feet high be excavated no steepe than

1.5H: 1 V in the fill and alluvial deposits. Flatter slopes may be required based on tine actual

conditions encountered, particularly where loose or soft soils are encountered, or iJ groundwater

is encountered. If wetted by surface water, the slopes may be subject to erosion. SJope

protection, such as a plastic covering weighted down with sand bags, should be emoloyed as

appropriate during construction to reduce the potential for erosion.

Consistent with conventional construction practice, temporary excavation slopes sho(tld be made

the responsibility of the contractor. The contractor is continually at the site and is , ble to

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observe the nature and conditions of the subsurface materials encountered, including

groundwater, and has responsibility for the methods, sequence, and schedule of construction. If instability is detected, slopes should be flattened or shored. Regardless of the construction

method used, all excavation work should be accomplished in compliance with applicable local, state and federal safety codes.

Stockpiles of materials or heavy equipment should be placed no closer than a distance equal to

the depth of the excavation from the top of the excavation slope.

8.5 Dewatering

Construction of the proposed bridge may require excavation below the groundwater table. The

level of the water table varies depending on the time of year; it is higher during the wet winter

and spring months and lower in the dry summer months. Consequently, dewatering may need o

be accomplished depending on the time of year construction and depth of the planned

excavation. Dewatering should be accomplished as necessary so that construction, i.e.,

excavation, form work, concrete placement, and backfilling, can be done in dry conditions.

During construction, groundwater levels should be maintained at least 2 feet below the level of

the excavation to prevent a blowout and/or heaving conditions. Construction dewatering would

be required if groundwater seepage up through the bottom of the excavation is anticipated or

observed during construction. Construction dewatering could include the use of sumps, well points, or dewatering wells.

The contractor should be made responsible for controlling all surface and groundwater whenever

encountered. The method of dewatering selected by the contactor should be evaluated by a

geotechnical engineer experienced in groundwater control. Improper dewatering methods could

damage the integrity of the foundation soils or cause a blowout and/or heaving condition. The

contractor should be responsible for evaluating the potential for bottom heave occurring in the

excavation and taking appropriate mitigation measures as appropriate.

8.6 Pile Installation

8.6.1 Pile-driving Equipment

Fixed-lead pile-driving equipment is recommended to drive the steel pipe piles. The use

of hanging or swinging leads is not recommended, unless they are constructed so that they can be

held in a fixed position during driving operations. Leads should be of sufficient length so that the use of followers will not be necessary.

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SHANNON ~•WILSON, INC.

An air-, steam-, hydraulic-, or diesel-powered hammer may be used for dr ving the

proposed piles. Section 8.6.2 presents preliminary analyses of hammer energy an~ stress for a

typical diesel-powered hammer driving 16- and 18-inch-diameter steel pipe piles with a wall

thickness of 0.5 inch. All pile-driving equipment should be designed, constructed and

maintained in a manner suitable for the work to be accomplished for this project. OCf, in the

opinion of the engineer, the driving equipment is inadequate or deficient, the engineer may direct

that it be removed from the job site. All costs for re-mobilizing, removing, or replacing such equipment should be at the contractor's expense. The contractor should furnish thie manufacturer's specifications and catalog for the hammer proposed.

8.6.2 Wave Equation Analysis

We performed preliminary Wave nquation Analyses for file driving (WEAP) for 16- and

18-inch-diameter, 'Ii-inch-thick wall steel pipe piles. We assume the piles would l e driven

closed-ended with a Delmag D 22-23 diesel hammer. The analyses were performc d for assumed

pile lengths of 55 to 60 feet, i.e., driving 5 to IO feet into the siltstone bedrock. Tl e hammer

sizes were selected based on our past experience. The analyses were performed ming the

computer program GRLWEAP (Version 2005), which was developed by Pile DynJllllics, Inc.

(PDI, 2005). Figures 5 and 6 summarize the results of our preliminary WEAP ana yses for 18-and 20-inch-diameter piles, respectively.

To establish the driving criteria for production piles, we recommend WEAJI> be

performed using data for the actual hammer/pile combination that will be used to c!five the production piles.

8.6.3 Monitoring Pile-driving

All pile-driving should be monitored by taking a continuous driving record of each pile.

For this purpose, the contractor should be required to mark the pile at 1-foot increnJents. During

final driving and any redrives, additional I-inch increments between the 1-foot ma1 ks would be required.

The pile-driving record should be complete. The form should have spaces 1IO record

hammer stroke (diesel hammers), blows per foot, time, date, reasons for delays, anc other

pertinent information. In addition, the record should include tip elevation, driving i-riteria, and

initials of inspectors making final acceptance of the pile. The pile-driving records i hould be

reviewed on a daily basis. For this purpose, we recommend that an experienced an i qualified

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SHANNON 6WILSON. INC.

geotechnical engineer familiar with the subsurface conditions of the project site be assigned to perform construction monitoring.

All driven piles should be checked for possible heave prior to cutoff. The heave should

be checked by surveying the elevation of each pile butt after a pile is driven within the group.

The heave data should be provided to the owner and engineer to determine if redrive will be

required. In general, if the heave is greater than 0.15 to 0.25 inch, the pile should be redriven to

the original cutoff or tip elevation. For pile groups, we recommend that the central piles be

driven first. Subsequent piles should be installed from the center out, proceeding in a radial

pattern or from one end to another.

It has often been difficult in the past to estimate the energy delivered by diesel hammers.

The Saximeter, developed by POI, can be used to record hammer strokes and provide an estimate

of the driving energy of diesel hammers. If the contractor selects a diesel hammer, we

recommend that a Saximeter be used during pile driving.

8.7 Wet Weather and Wet Condition Considerations

In the project area, wet weather generally begins about mid-October and continues through about

May, although rainy periods could occur at any time of year. Therefore, it would be advisable to

schedule earthwork during the dry weather months of June through September. During wet

weather months, the groundwater levels could rise, resulting in seepage into site excavations.

Performing earthwork during dry weather would reduce these problems and costs associated with

rainwater, trafficability, erosion control, and handling of wet soil. However, should wet

weather/wet condition earthwork be unavoidable, the following recommendations are provided:

•

•

•

The ground surface in and surrounding the construction area should be sloped as much as possible to promote runoff of precipitation away from work areas and to prevent ponding of water.

Work areas or slopes should be covered with plastic. The use of sloping, ditching, sumps, dewatering, and other measures should be employed as necessary to permit proper completion of the work.

Earthwork should be accomplished in small sections to minimize exposure to wet conditions. That is, each section should be small enough so that the removal of unsuitable soils and placement and compaction of clean structural fill could be accomplished on the same day. The size of construction equipment may have to be limited to prevent soil disturbance. It may be necessary to excavate soils with a backhoe, or equivalent, and locate them so that equipment does not pass over the excavated area.

21-1-12294-001-RI .docx/wpl)kn 21-1-12294-001

12

SHANNON &1 MLSON. INC.

• Fill material should consist of clean, well-graded, pit-run sand and grawl soils, of which not more than 5 percent fines by dry weight passes the No. 200 rr esh sieve, based on wet-sieving the fraction passing the %-inch mesh sieve.

• No soil should be left uncompacted and exposed to moisture. A smoothi-drum vibratory roller, or equivalent, should roll the surface to seal out as mucl!l water as possible.

• In-place soil or fill soil that becomes wet and unstable and/or too wet to suitably compact should be removed and replaced with clean, granular structural fill.

• Excavation and placement of structural fill material should be observed pn a full-time basis by a geotechnical engineer (or representative) experienced in wet weather/wet condition earthwork to determine that all work is being accomplished in accordance with the project specifications and our recommendations.

• Grading and earthwork should not be accomplished during periods ofhrnvy, continuous rainfall.

We recommend that the above requirements for wet weather/wet condition earthwoirk be incorporated into the contract specifications.

9.0 ADDITIONAL SERVICES

We recommend that Shannon & Wilson, Inc. be retained to review those portions of the plans

and specifications pertaining to foundations and earthwork to determine if they are C< nsistent with

our recommendations presented in this report. We also recommend that we be retained to

provide observation services for the geotechnical aspects of construction.

10.0 LIMIT A TIO NS

This report was prepared for the exclusive use of H.W. Lochner, Inc. for design anc construction

of the proposed Black Creek Bridge No. 7 replacement located in Grays Harbor County,

Washington. The report should be provided to prospective contractors for informabon of factual

data only, and not as a warranty of subsurface conditions, such as those interpreted from the

boring log and discussions of subsurface conditions included in this report.

The analyses, conclusions, and recommendations contained in this report are based K>n site

conditions as they presently exist. We assume that the exploratory boring made for this project

are representative of the subsurface conditions throughout the site; i.e., the subsurfape conditions

everywhere are not significantly different from those disclosed by the explorations. If conditions

different from those described in this report are observed or appear to be present during

construction, we should be advised at once so that we could review these condition, and

21-1-12294-001-Rl.docx/wp/lkn 21-1-12294-001

13


reconsider our recommendations, where necessary. If conditions have changed because of

natural forces or construction operations at or near the site, we recommend that this report be

reviewed to detennine the applicability of the conclusions and recommendations considering the

changed conditions and time lapse.

Within the limitations of the scope, schedule and budget, the analyses, conclusions, and

recommendations presented in this report were prepared in accordance with generally accepted

professional geotechnical engineering principles and practice in this area at the time this report

was prepared. We make no other warranty, either express or implied.

The scope of our services did not include any environmental assessment or evaluation of

hazardous or toxic materials in the soil, surface water, groundwater, or air at the subject site

other than those described in this report. Shannon & Wilson, Inc. has qualified personnel to

assist you with these services should they be necessary.

Shannon & Wilson, Inc. has prepared Appendix C, "Important Information About Your

Geotechnical Report," to assist you and others in understanding the use and limitations of our

reports.

SHANNON & WILSON, INC.

Christopher A. Robertson, P.E., L.E.G. Vice President

YEZ:CAR/yez

21-l-12294-001-RI docx/wp/lkn 21-1-12294-001

14

SHANNON & ILSON. INC.

11.0 REFERENCES

American Association of State Highway and Transportation Officials (AASHTO), 2 07, AASHTO LRFD bridge design specifications, customary U.S. units, (41h ed.), 2 09 interim revisions: Washington, D.C., AASHTO, 1 v.

American Association of State Highway and Transportation Officials (AASHTO), 2 09, AASHTO guide specifications for LRFD seismic bridge design, customary U .. units, (1th ed.): Washington, D.C., AASHTO.

ASTM International (ASTM), 2009, Annual book of standards, construction, v. 4.08 soil and rock (I): D 420 - D 5876: West Conshohocken, Penn., ASTM International, 1 v.

Ensoft, Inc., 2007, Computer program LPILEPLUS, version 5.0, technical manual: a rogram for the analysis of piles and drilled shafts under lateral loads: Austin, Tex., Ensoft, Inc.

Idriss, I. M. and Boulanger, R. W., 2006, Semi-empirical procedures for evaluating iquefaction potential during earthquakes: Soil Dynamics and Earthquake Engineering, v. 26, no. 2-4, p. 115-130.

Mononobe, N., 1929, Earthquake-proof construction of masonry dams: Proceeding , World Engineering Conference, v. 9, p. 275.

Okabe, S., 1926, General theory of earth pressure: Journal, Japanese Society of Civ 1 Engineers, v. 12, no. 1.

Pile Dynamics, Inc. (POI), 2005, Computer program GRLWEAP; Wave equation driving: Cleveland, Ohio, Pile Dynamics, Inc.

Seed, R. B.; Cetin, K. O.; Moss, R. E. S.; and others, 2003, Recent advances in soil iquefaction engineering: a unified and consistent framework, in 26th Annual ASCE Los geles Geotechnical Spring Seminar, April 30, 2003, Long Beach, Calif., Proceedin s: Long Beach, Calif., American Society of Civil Engineers, 71 p.

Youd, T. L.; Idriss, I. M.; Andrus, R. D.; and others, 2001, Liquefaction resistance o soils: summary report from the 1996 NCEER and 1998 NCEER/NSF workshops o evaluation of liquefaction resistance of soils: J oumal of Geo technical and Geoenvironm ntal Engineering, v. 127, no. 10, p. 817-833.

21-1-12294-001-Rl.docx/wp/lkn 1-1-12294-001

15


TABLE 1 RECOMMENDED PARAMETERS FOR

DESIGN RESPONSE SPECTRA CONSTRUCTION

Peak Horizontal Ground Acceleration Coefficient, PGA

Site Class

Site Coefficient for Peak Ground Acceleration, Fpga

Site Coefficient for 0.2-sec Period Spectral Acceleration, F.

Site Coefficient for 1.0-sec Period Spectral Acceleration, Fv

0.2-sec Period Spectral Acceleration Coefficient, s.

1.0-sec Period Spectral Acceleration Coefficient, S1

Design Spectral Acceleration Coefficient at 0.2-sec Period, S0s

Design Spectral Acceleration Coefficient at 1.0-sec Period, Sm

21-1 -12294-001-RI-TI .doc.Jwp/lkn

0.44g

D

1.1

1.0

1.5

1.36g

0.62g

0.91g

0.62g

21-1-12294-001

TABLE2

RECOMMENDED PARAMETERS1 FOR DEVELOPMENT OF P-Y CURVES USING LPILE

0 1.5 Sand 120 . . 28 28 1.5 4.5 Silt 105 200 100 25 25 4.5 10 Sand 95 . . 25 25

B-1 I IO 42 Llquefiable

32.6 . . 25 5 Soil

42 45 Sand 62.6 . . 32 8 45 50 Soft Clay 47.6 400 200

50 59 Weak Rock 72.4 . . I . I . Notes: 1

Parameters given above are based on subsurface conditions encountered in boring B-1 along the project alignment.

Effective Unit Weight= Total Unit Weight - 62.4 pcf ft= feet pci = pounds per cubic inch psf = pounds per square foot psi = pounds per square inch RQD = rock quality designation

1-1-12294-001-RJ-12.xlsx

125 125

80 80

90 90

90 22

I 100 I 25

I 800 I 800 I 70

SHANNON & WILSON, INC.

J 500 I 0.0004

21-1-12294-001

I ci.

~ ·"' "" C

.;;! >

I ';

5

! ~ ~ -, iri E

0 4000 8000

Approximate Scale in Feet

NOTE

Map adapted from electronic CD ROM USGS topographic map by TOPOfti"-'2000 National Geographic Holdings.

Black Creek Bridge No. 7 Replacement Grays Harbor County, Washington

VICINITY MAP

j N

l

August 2009 21-1-12294-001

j

~L..------------..... --~--------------------------..J...--------------------"""""--------.... SHANNON & WILSON, INC. FIG. 1 G,,otechnical and Environmental Coowllants

~1

t ij ~

~ ~ t

ff-ij :g, ,,,

~ 5 ij

~ "'

/

/

(,{#'i-

0\f>r.,'f.

/

r,i#'f.

q;,\,;,."'f.

/ PROPOSED TEMPORARY BYPASS BRIDGE

'.._,·,

J N

l 10:)

Scair~ 1n Feet

l:EQFND

13-1

1';,QJ:f

Black Creek Bndge No_ 7 Reo!acement Grays Harbor County. Washington

SITE AND EXPLORATION PLAN

2009 21,1, 12294-001

SHANNON & WILSON, INC, ,::,r,, '>

ASSUMED SUBSURFACE PROFILE

l:Li~ed -(in Nearby E.xpio!F!ir--:ins 13.j

:,· l----~~~----1 $;:indyS,LT, ML

S1ltySi\ND. SM

4j' >----------; S-Mld~· G,'.t,VU, GM

fJ.iy!'VS!LTt,) s.:HtyCU\Y,

t,,1!JC

SC, -·-········]

Bottom of 8-nnrts at ,;9 c fh:t

t ~ :!:

!i: ~ !e

10

20

; 30

ii

4(:

5C

60

1\

' \ \ \ \ \ \

20

\ \ \ \ \

4()

STRENGTH UMIT REStST ANCE ttons}

STRENGTj:i UMIT NOTES: 1 Ra(:eff'm~ndec rac:o~ s O <!5 for side afld be$€ tet.istan,:;e

St:afl L;Jt,tl c2pw:ty ,s e::;timated \)y ;. s n] !he unta-c:lorW side resi:w.mce shown ?.hov,: 3nd s res•.s!a:1,:-e tac-01 of O 35

GENERAL NOTES 1 The a11alyses wer,e oerfo-rned ba,;e1i

cioeefy spa-eea :::.hcift:s 1 c.-o.ser tr ,;in ·''Clt.1ded n loc:.i exper1erce The ar,alyses are t,ased

I :c !i: UJ Cl <l. ;: w _, ii:

20

30

5•1

6J

" ,,

I <:{

1 Rt1<:::>nnw,ced

EXTREME E\/ENT LIMIT

RESISTANCE (tons)

!GO

{see Extreme Event Limit NoifJ 2)

tase res•starit::e ~re ~ and 0.8 for aw.i _,p,i+t res;:.,e,:;tvely

Ui:facu:,red ".:lcw0-;:n;1g for;;,: s est,rn3~-&{! to be 10 ton!·, A load fa~t:,r i)f 1 25 ,!s

,e:c,m,'"''"Wc 1-e (.:derrnme fa;:;nrej do-Y'tnQr39 brc.e Downdog brce is ·ecomme-1ded to.;, t>e ;=mr.n,:,,j ·N,th p0st-e.ar'.t:q1.,a>se ic.;;idl"l9

s•ngk, st:;!ft <E1d dv w,· (<:r,".c-,1dw ;p::uo Creek Bndge No 7 Replacement Grays Harbor County Washngton

Fac..torad total seaft resi<,1:an,,e S'lt1w·n ~. , t,lots 1.$ .-:Jeten11ned t,y Iiddirig its ur.faelor!:!d iiide .and Q;:i,:--.e "f:'S1stances '.l'l...<it,p1K•J uy she ap0rcp~1.r-:2 ,es,;:,t:m::-.e tactor,:; a~ m,ted atove AXIAL PILE RESISTANCE OF

2A-1-12294AJ01

FIG. 3

4.5

·:r

ASSUMED SUBSURFACE PROFILE

B-1

Sih'<'.',\ND. SM

(l,,tt-:'i ',l, :" -0 ,;!· ~ (1 X"

:\rh/':

Gu.ten• :,i

! i'= ""' Cl

";:::

"' .., ii

20

.l(j

\ I

\

STRENGTH LIM!T RESISTANCE (tons1

60 80 iGO 1?0

\ \ \ \

S1aft u;.J'ifl co~acity is est;ma~ed snown abvve ,,rd roco,nrr:erided resist.an~ fac!w uf O

rr.~ !l'•~lyses were ptrrformed b3S€d on guidel,ries 1paced shaf1_s 1c:0s~r than 3 diameters ::::e:irer t,,:, r-.R;,\er 1

Factored (:)ta1 shaft res,s'.;mre srowr on r!::ns is .-ie!ecrrnrn,;,J ,,y -:10dn:; rs nol!..::d abc'le

:.:'.00

~- 2G

~ :,: f-a. w a

I 0

0. ! ;:: w 30 ~ _, I ,1 0::

I

60

,;;"l.,:;h-sf·S M<:; t,s1st;i on <! s.n;te s.!nft

<;,de ~)ill'. t:·/ise res;stans~s. med r-liea by the apprn;;nate

SC,

!;XTREME EVENT LIMIT RESISTANCE (tons)

BO

to Other

{sev Extmme fvem Lmut Note 2}

EXTREME EVENT UMIT _NQ}ES ~

1 He-::urn,·w~nded re~is\str:c:e ~acto"s ~or :10th :>!Ge ('.O:n;,q:1ssK•"' .and :;p/1~ r~spe( evt~,y

? Unfactored down::!ril9 f,:,:,rce ,s e,;t1ma:e0 1;:: reuirn,nt"nded to deiwmme facl:::reG dnw'lctr;,9 fr:,;-,; to ae .Jf,pllE-:d with µ0st-earthquake k,a-J<n<J

{)f B:ack C.regk

facto~s <>1s

are 1 ,<~GD 8 fDr

2~ ,$

s rt:!-ccrrnner:-ded

? Rep!acemert V'vashington

EST!!I/IA TED AXIAL PILE RESISTANCE OF 18-IN-DIA , %-INCH WALL, STEEL PIPE

PILE, DRIVEN CLOSED-ENDED

21- l--'!2294-00\

F!G.4

600

'ii, 500 Q.

;g_ .?;- 400 ·u Ill Q. Ill t) 300 .!! Ill .§ 200 5

100

0

36.0

34.0

! 32.0

:I 30.0 I!! Iii 28.0 C 0

26.0 ·;;; .., e

24.0 Q.

E 0

22.0 0

~ 20.0 :ii:

18.0

16.0

25

i! 24

l 23 CD a'. 22

! 21 0

1-B 20

) 19 E ~ 18

~ » 17 e> CD in 16

15

0

0 50 100 150 Driving Resistance (blows/foot)

I i i

I

----/ /

-·-

J


·-·-

~

\ .,.,..-~~

,,,....

50 100 150 Driving Resistance (blows/foot)

LEGEND

C.O.R. = Coefficient of Restitution Q=Soil Quake D = Soil Damping

NOTES:

200

200

200

8.5

-8.0

7.5

7.0

'i

I~ /1 '

I 6.5 ~ CD

.Jt! 6.0 I I g VJ

5.5 I i

5.0

' 4.5 ' I

4.0 I


200

~ ';;' 2.0 +------1--r---+----+------J

£ VJ C 1.5 +------,i"------+----+------1 0 ·;;; C

~ 1.0 +---l'~--1-----+----+------l

= :ii: 0.5 +------1,--------+----+-----t

0

I Materia Total Length Penetration

X-Sect. Area Elast. Modulus

C.0.R. Spec. Weight

Circumference Yield Strength (fy)


GRLWEAP INPUT PARAMETERS

Pile Data Steel 60 60

24.4 30,500 ksi

0.8 ~500- -

-4.19 ft 36 ksi

Hammer Data Delmag D 22-23

Helmet ~ight I 1.9 ] Efficiency 0.8 J

Hammer Cushion ----Thiclmess 2

Area 227 Elast. Modulus 530

C.O.R. 0.8

200

Pile Cushion Soil Parameters

Thick~::~-Elast. Modulus -

C.0.R. -

a (in.) D (sec/ft)

STha08ftj __ o._1_~_0_.os_~j _ 0.15 0.15 .

Shaft Resist. '--1 _5_0_% _ _,

Black Creek Bridge No. 7 Replacement

Grays Harbor County, Washington

WAVE EQUATON ANALYSIS 16-INCH-DIA., 1/2-INCH WALL STEEL PIPE PILE,

DRIVEN WITH DELMAG D 22-23 1. The computer program GRLWEAP (Version 2005) was used with the above

assumed input parameters to perform the analyses. Au ust 2009 21-1-12294-001 2. Standard GRLWEAP recommended values used for hammer data. SHANNON & WILSON, INC. FIG. 5

Geotechnical and Environmental Consultants

700

600

~ .e. 500

c >,

400 ;ta: u ca Q. ca 0 300 Q)

1u E

200 5 100

0

36.0

34.0

"iii 32.0 c C/1 30.0 C/1 e u; 28.0 C .Q 26.0 Cll C/1 !!!

24.0 0. E 8 22.0

>< ca 20.0 :i;

18.0

16.0

25

ii? 24 ul g 23 Q) a: 22 -0 o. 21 {!. .2 20

I 19 E ~ 18 ~ >- 17 e> GI

ifi 16

15

0


I

--

/ ---

/ I ~

0

' \ ~


---_.V

~ 100 1~ Driving Resistance (blows/foot)

LEGEND

C.O.R. = Coefficient of Restitution Q = Soil Quake D = Soil Damping

NOTES:

200

200

-·--

___ .. __

200

8.5

8.0

7.5

7.0

~ 6.5 ~

Q)

"" 6.0 e w 5.5

5.0

4.5

4.0

0

3.5

3.0

-!2.5 C/1 Cll

!: 2.0 VJ C 0 ·~ 1.5 GI I-

~ 1.0 ~

0.5

0.0

0

Material Total Length Penetration

X-Sect. Area Elast. Modulus

C.O.R. Spec. Weight

Circumference

Yield Strength (fy)

50 100 150 Driving Resistance blows/foot)

GRLWEAP INPUT P

Pile Data Steel

60 60

27.5 30,500 ksl

0.8 500

4.71 ft 36ksi

Hammer Data Delmag D 22-23

Hel et Weight I 1.9 Efficiency 0.8

H mmer Cushion ,----~

2 Area 227

Elas . Modulus 530 C.O.R. 0.8

200

200

Pile Cushion Soil Parameters

Thickness~ Area -

Elast. Modulus -

C.O.R. -

Q (in.) D (sec/ft)

sTh ft~~o_._1~+--0_._oo~~ . 0.15 0.15

Shaft Resi t.J ~ _4_3_%_~


Grays Harbor Co nty, Washington

WAVE EQUA N ANALYSIS 8-INCH-DIA., 1/2-INCH ALL, STEEL PIPE PILE

DRIVEN WITH ELMAG O 22-23 1. The computer program GRLWEAP (Version 2005) was used with the above

assumed input parameters to perform the analyses. Au ust2009 21-1-12294-001

2. Standard GRLWEAP recommended values used for hammer data. SHANNON & WILSO Geotechnical and Environmental

FIG.6

APPENDIX A

SUBSURFACE EXPLORATIONS


21-1-12294-001

SHANNON t WILSON. INC.

APPENDIX A


TABLE OF CONTENTS

Page

A.1 GENERAL ..................................................................................................................... A-1

A.2 DRILLING .................................................................................................................... A-1

A.3 TESTING AND SAMPLING ........................................................................................ A-1

A.4 REFERENCE ................................................................................................................ A-2

FIGURES

A-1 Soil Classification and Log Key (2 sheets) A-2 Log of Boring B-1 (2 sheets)

21 • l • 12294-001-RI ·AA.docx/wp/lkn 2 l-1-12294-00 l A-i

SHANNON ~WILSON, INC.

APPENDIX A


A.1 GENERAL

The field exploration program for the proposed Black Creek Bridge No. 7 replacement consisted

of drilling and sampling one boring. The approximate location of the boring is shown in the Site

and Exploration Plan, Figure 2 in the main text of this report. The location and elevation of the boring was estimated from features shown on drawings provided by H.W. Lochner.

A.2 DRILLING

Boring B-1 was drilled on July 30, 2009, using a Mobile B-61 truck-mounted rig by Holocene

Drilling of Fife, Washington, under subcontract to Shannon & Wilson, Inc. Boring B-1

(Figure A-2) was advanced to approximately 58.9 feet below ground surface using mud-rotary

drilling methods. Soil samples are taken from the bottom of the boring using a split-spoon sampler.

A representative from Shannon & Wilson was present to observe drilling and sampling

operations, retrieve representative soil samples for subsequent laboratory testing and prepare descriptive field log of the boring.

Upon completion of boring B-1, the borehole was filled with bentonite chips and the surface covered with an asphalt cold patch.

A.3 TESTING AND SAMPLING

Standard Penetration Tests (SPTs) were performed in the borings at approximately 2.5-foot

intervals in the upper 20 feet and at 5-foot intervals thereafter. SPTs were performed in general

accordance with the ASTM International (ASTM) Designation: D 1586, Standard Method for

Penetration Test and Split-Barrel Sampling of Soils. The SPT consists of driving a 2-inch.

outside-piameter, split-spoon sampler a total distance of 18 inches into the bottom of the boring

with a 140-pound hammer falling 30 inches. The number of blows required to cause the last 12 inches of penetration is termed the Standard Penetration Resistance (N-value). When

penetration resistances exceed 50 blows for 6 inches or less of penetration, the test is terminated

and the number of blows and the corresponding penetration are recorded. The N-values were recorded by a representative from our firm and are plotted on the log of each boring. The

N-values provide a means for evaluating the relative consistency (stiffness) of cohesive soils and

21-1 ·I 2294-001 -R 1-AAdocx/wp/lkn 21-1-12294-001

A-1

SHANNON~ WILSON. INC.

the relative compactness or density of cohesionless (granular) soils. A more detai ed description

of the N-values and how they relate to soil characteristics is presented in Figure A 1.

The split-spoon sampler used during the penetration testing recovers a disturbed sample of the

soil, which is useful for identification and classification purposes. The samples w1 re field

classified and recorded on the logs by our field representative. The samples were ~ealed in jars

and returned to our laboratory for testing. Laboratory testing was later performed pn selected

samples. The results of the testing are presented in Appendix B, Geotechnical Lal oratory Test Results.

A.4 REFERENCE

ASTM International (ASTM), 2009, Annual book of standards, construction, v. 4.1p8, soil and rock (I): D 420 - D 5876: West Conshohocken, Penn., ASTM Intemationa, 1 v.

2 J-J. J 2294-001-R 1-AA.docx/wp/lkn 21-1-12294-001 A-2

Shannon & Wilson, Inc. (S&W), uses a soil GRAIN SIZE DEFINITION classification system modified from the Unified DESCRIPTION SIEVE NUMBER AND/OR SIZE Soil Classification System (USCS). Elements of the uses and other definitions are provided on FINES < '#200 (0.08 mm) this and the following page. Soil descriptions

SAND* are based on visual-manual procedures (ASTM '#200 to #40 (0.08 to 0.4 mm) D 2488-93) unless otherwise noted. - Fine

- Medium #40 to #10 (0.4 to 2 mm) - Coarse #10 to #4 (2 to 5 mm)

s&W CLASSIFICATION GRAVEL* OF SOIL CONSTITUENTS

#4 to 3/4 inch (5 to 19 mm) - Fine • MAJOR constituents compose more than 50 - Coarse 3/4 to 3 inches (19 to 76 mm)

percent, by weight, of the soil. Major consituents are capitalized (i.e., SAND). COBBLES 3 to 12 inches (76 to 305 mm)

• Minor constituents compose 12 to 50 percent BOULDERS > 12 inches (305 mm) of the soil and precede the major constituents

(i.e., silty SAND). Minor constituents • Unless otherwise noted, sand and gravel, when preceded by "slightly" compose 5 to 12 present, range from fine to coarse in grain size. percent of the soil (i.e., slightly silty SAND).

• Trace constituents compose O to 5 percent of RELATIVE DENSITY I CONSISTENCY the soil (i.e., slightly silty SAND, trace of gravel). COARSE-GRAINED SOILS FINE-GRAINED SOILS

N, SPT, RELATIVE N, SPT, RELATIVE MOISTURE CONTENT DEFINITIONS BLOWS/FT. DENSITY BLOWS/FT. CONSISTENCY

Dry Absence of moisture, dusty, dry 0-4 Very loose Under 2 Very soft

to the touch 4 - 10 Loose 2-4 Soft 10-30 Medium dense 4-8 Medium stiff

Moist Damp but no visible water 30-50 Dense 8- 15 Stiff

Wet Visible free water, from below Over SO Very dense 15- 30 Very stiff

water table Over 30 Hard

ABBREVIATIONS WELL AND OTHER SYMBOLS

ATD At Time of Drilling • Bent. Cement Grout [~! Surface Cement Elev. Elevation Seal

ft feet m Bentonite Grout - Asphalt or Cap

FeO Iron Oxide

ffillJ t!~~1 Slough MgO Magnesium Oxide

Bentonite Chips

HSA Hollow Stem Auger CJ Silica Sand ~ Bedrock . .

ID Inside Diameter

in inches 00 PVC Screen

lbs pounds []J Mon. Monument cover Vibrating Wire .

N Blows for last two &-inch increments

NA Not applicable or not available

NP Non plastic

OD Outside diameter

OVA Organic vapor analyzer ~ PID Photerionization detector ~ b ppm parts per million Cl PVC Polyvinyl Chloride Black Creek Bridge No. 7 Replacement ~ I ss Split spoon sampler Grays Harbor County, Washington II)

SPT Standard penetration test ... Q.

USC Unified soil classification (!)

'if, WOH Weight of hammer SOIL CLASSIFICATION l:i ...

AND LOG KEY ;;. WOR Weight of drill rods ;;; WLI Water level indicator 5 August2009 21-1-12294-001 0

Cl SHANNON & WILSON, INC. l FIG. A-1 z

ii: Geolechnk;al and Environmental Consultants Sheet 1 of 2 0 a,

Clean Gravels (less than 5%

Gravels fines) GP (more than 50%

of coarse fraction retained

GM on No. 4 sieve) Gravels with Fines

COARSE- (more than 12%

GRAINED fines) GC SOILS

(more than 50% retained on No. SW 200 sieve) Clean Sands

(less than 5% fines)

Sands SP

(50% or more of coarse fraction

passes the No. 4 Sands with SM

sieve) Fines

(more than 12% fines) SC

ML

Silts and Clays Inorganic

(liquid limit less CL than 50)

FINE-GRAINED Organic Ol SOILS (50%ormore

passes the No. 200 sieve) MH

Silts and Clays Inorganic

(liquid limit 50 or CH more)

Organic OH

HIGHLY- Primarily organic matter, dark in ORGANIC PT SOILS color, and organic odor

NOTE: No. 4 size= 5 mm; No. 200 size= 0.075 mm

2 c, 1. Dual symbols (symbols separated by a hyphen, i.e., SP-SM, slightly "3. silty fine SAND) are used for soils with between 5% and 12% fines ~ or when the liquid limit and plasticity index values plot in the Cl-ML "' area of the plasticity chart. i;i

..... .... . . . . . . ... ..... .... ..... .. .. .· ···.· .. :.·· :.·· ·····:······ ···•········

Poorly graded gravels, ravel-sand mixtures, little or no fin s

Silty gravels, gravel-sa d-silt mixtures

Cl_~y gravels, gravel- and-clay m1 ures

Well-graded sands, gra little or no fines

elly sands,

Poorly graded sand, gr little or no fines

velly sands,

Silty sands, sand-silt m tu res

Clayey sands, sand-cla mixtures

lnor~anic clays of low t medium plas city, ~ravell~ clays sandy clays, silty clays, ean cays

Organic silts and organ low plasticity

c silty clays of

lnor~anic clays or medi m to high plas icily, sandy fat cla , or gravelly fat clay

to high

Peat, humus, swamp s organic content (see A

ilswilh h~ TM D44 )

Black Creek Bridge o. 7 Replacement Grays Harbor Co nty, Washington

SOIL CLAS IFICATION AND L GKEY

"'0:5 2. Borderline symbols (symbols separated by a slash, I.e., CL/ML, silty August 2009 21-1-12294-001

CLAY/clayey SILT; GW/SW, sandy GRAVEUgravel/y SAND) i indicate that the soil may fall into one of two possible basic groups. SHANNON & WILSO FIG. A-1 a:o- Geotechnlcal and Environmental Sheet 2 of 2 m1., ______________________________________________________ __. ____________________ ,... ______ .._-:,.:;;;.;,;..,. __ ~

Total Depth: 58.9 ft. Northing: Drilling Method: MudRota!l'.. Hole Diam.: 6in.

Top Elevation: - Easting: Drilling Company: Holocene Drillina Rod Diam.: 2-inch

Vert. Datum: Station: Drill Rig Equipment: B61 TruckRfg_ Hammer Type: Automatic

Horiz. Datum: Offset: Other Comments:

SOIL DESCRIPTION ¢: 0 rJ) 'C ... ;;:: PENETRATION RESISTANCE (blows/foot) (I)

Refer to the reporl text for a proper understanding of the £ .0 a. C: (I) t J,. Hammer Wt. & Drop: 140 lbs I 30 inches subsurface materials and drilling methods. The stratification E E

::, iii C. a~ lines indicated below represent the approximate boundaries (I) ~ Ill (I)

0 en 0 between material types, and the transition may be gradual. 0 20 40 60

!"\ASPHALT. r U.;j ...... \Sandy GRAVEL; (fill)·GW. I 1.5 ~

1I t •• Very soft, brown, clayey, fine sandy Sil T;

,,

\moist; trace of organics; ML r 4.5 -· .. 2I 5 . -·. :·: A WOH ..

~ Ve,y loose, brown, trace to sl;ghtly clayey, ..

r 7.0 ' .Jlt silty, fine SAND; moist; trace of organics, 31 , .

.. .. Yl. .. iron-oxide staining; SM.

.. ,;: :•: "' 10 -

41 .£ . ·-Very loose to loose, brown and gray, silty, fine

.. ~ .. .

· .. :·: to medium SAND; moist to wet; trace to

.. "' <> •• C .. sI 'C

numerous organics, wood and silt clasts, 8 ,,WOH

prevalent wood fragments between .• .. . ..;.

.. sI 15 ·-approximately 15 and 30 feet, iron-oxide

-:: :·. ~····· ..

staining above approximately 16 feet; SM. •' .. 71 .we= 1

.. I&

20 Note: High water content between 15 and 30

.. sI .•. A •' .. feet is associated with the high organic

..

content and does not represent the 9I .. ~

WO, 4

..

actual water content of the inorganic .. 25 fraction of the soil.

,• ..

l. .. · .. :·: . ':'ii>. b :=::.10I ,:: :·: 30 I .. <>

• •• :·: 11 [ .;·

,• .. 35 .. · . .. ..

' • .. :·:·12I •' .. 40

~ f,;: .. :· ·~ 42.0 ~~ii. , ....

Loose, gray, trace of clay to locally clayey, 131 ' .. ~··

silty, sandy GRAVEL; moist; rounded to :1 /

;.: ""\angular volcaniclastics; GM. r 45.0 t 45

···L__ .. '"'

Soft, gray, slightly fine sandy to fine sandy, ...... . " ....... .....

• •• slightly clayey to clayey SILT to silty CLAY; 141 .. . ... . . . .. .. . .

r---...:__ CONTINUED NEXT SHEET

0 20 40 60 LEGEND 0 % Fines (<0.075mm)

* Sample Not Recovered 'fl_ Ground Water Level ATD • % Water Content I Standard Penetration Test Plastic Limit I • I Liquid Limit

Natural Water Content


~ Grays Harbor County, Washington

1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions. 2. The stratification lines represent the approximate boundaries between soil types, and the

LOG OF BORING B-1 transition may be gradual. 3. The discussion in the text of this report is necessary for a proper understanding of the

nature of the subsurface materials. 4. Groundwater level, if indicated above, is for the date specified and may vary. August2009 21-1-12294-001

5. uses designation is based on visual-manual classification and selected lab testing. SHANNON & WILSON, INC. I FIG.A-2 Geolechnical and Environmental Consuttants Sheet 1 of 2

REV1

Total Depth: 58.9ft. Northing: _____ _ Drilling Method: Mud Rotary Hllle Diam.: 6 in. Top Elevation: ___ -__ Easting: _____ _ Drilling Company: Holocene Drilling Rdid Diam.: 2-inch

Vert. Datum: Station: _____ _

Horiz. Datum: ____ _ Offset: Drill Rig Equipment: .2,B~6.L1.!.;Tru=ck"--'--'®"". '---Other Comments:

H1mmer Type: _~A_ut~om~ati~·c_

SOIL DESCRIPTION Refer to the report text for a proper understanding of the

subsurface materials and drilling methods. The stratification lines indicated below represent the approximate boundaries between material types, and the transition may be gradual.

\wet; bedded, scattered silt clasts, trace to / scattered organics; MUCL.

SILTSTONE: Soft to low hardness, brown-gray; thin bedded to laminated with silt partrings; disturbed bedding; moderately to slightly weathered (Montesano Formation).

BOTTOM OF BORING COMPLETED 7/30/2009

¢:! E .c li E Q) >,

Cl en 50.0

58.9

• Sample Not Recovered SJ. Ground Water Level ATD Ol

~ g _j

§

I Standard Penetration Test

z < I <I)

~ NOtES

VJ Q)

C. E m en

151

16I

c, 1. Refer to KEY for explanation of symbols, codes, abbreviations and definitions.

~.· 2. The stratification Ines represent the approximate boundaries between soil types, and the • transition may be gradual. ;:; 3. The discussion in the text of this report is necessary for a proper understanding of the w nature of the subsurface materials.

8 4. Groundwater level, if indicated above. is for the date specified and may vary. ...J

"O ,_ C Q)

::i 1ii ~;:

¢!

£ C. Q)

Cl

55

60

PENETRATI ON RESISTANCE (blows/foot)

• 0

HammerW I. & Drop: 140 lbs I 30 inches

20 40 60

, .. -~ ·' ,.

19 ,.

....

. ..... .

..... : ... ........

0 ~ Fines (<0.075mm)

• 01 Water Content

.... · .......

90/11",

. .....

..

Plastic Limit ~ ~ Liquid Limit Natutlll Water Content

Black Creek Bridge No. 7 Replacement Grays Harbor Co1 nty, Washington

LOG OF Bl )RING B-1

August2009 21-1-12294-001 a: 5. USCS designation is based on visual-manual classification and selected lab testing. ~ SHANNON & WILSON, INC. I FIG. A-2 < Geotechnical and Environmental Con, ultants Sheet 2 of 2 ~ .... ____________________________________________________ .,_ __________________ ~--------------~~ ....

RFV1

PLL=66


APPENDIXB

GEOTECHNICAL LABORATORY TEST RESULTS

21-1-12294-001

SHANNON & ILSON. INC

APPENDIXB

GEOTECHNICAL LABORATORY TEST RESULTS

TABLE OF CONTENTS

Page

B.l INTRODUCTION ........................................................................................................... B-1

B.2 VISUAL CLASSIFICATION .............................................................. , ......................... B-1

B.3 WATER CONTENT DETERMINATION .................................................................... B-1

B.4 GRAIN SIZE ANALYSIS ............................................................................................. B-2

B.5 ATTERBERG LIMITS TESTS ...................................................................................... B-2

B.6 ORGANIC CONTENT .................................................................................................. B-2

B.7 REFERENCE ................................................................................................................. B-2

FIGURES

B-1 Grain Size Distribution, Boring B-1 B-2 Plasticity Chart, Boring B01

21-1-12294-001-Rl-AB.docx/wp/lkn 1-1-12294-001

B-i


APPENDIXB

GEOTECHNICAL LABO RA TORY TEST RESULTS

B.1 INTRODUCTION

This appendix contains descriptions of the procedures and the results of geotechnical laboratory

tests performed on soil samples obtained from field explorations for the proposed Black Creek

Bridge No. 7 Replacement. Samples from subsurface explorations were tested to evaluate the

basic index and engineering properties of the subsurface soils.

Laboratory testing was performed at the Shannon & Wilson, Inc. laboratory in Seattle,

Washington. Geotechnical laboratory testing consisted of visual classification, water content

determination, grain size analyses, Atterberg limits, and organic contest tests.

B.2 VISUAL CLASSIFICATION

Each soil sample recovered from the borings was visually reclassified in our laboratory using a

system based on the ASTM International (ASTM) Designation: D 2487, Standard Test Method

for Classification of Soil for Engineering Purposes and ASTM Designation: D 2488, Standard

Recommended Practice for Description of Soils (Visual-Manual Procedure). These ASTM

standards generally use the Unified Soil Classification System (USCS). The USCS is described

in Figure A-1 of Appendix A. The visual classification made using this system allows for

convenient and consistent comparison of soils from widespread geographic areas.

Sample classifications have been incorporated into the soil descriptions on the boring log

presented in Figure A-2.

B.3 WATER CONTENT DETERMINATION

The water content of all soil samples recovered from the field explorations was determined in

general accordance with ASTM Designation: D 2216, Standard Method of Laboratory

Determination of Water (Moisture) Content of Soil, Rock, and Soil-Aggregate Mixtures.

Comparison of water content of a soil with its index properties can be useful in characterizing

soil unit weight, consistency, compressibility, and strength. Water contents are plotted on the

boring logs presented in Appendix A.

21. 1 · 12294-001 ·Rl ·AB.docx/wp/lkn 21-1-12294-001

B-1

SHANNON & LSON. INC.

B.4 GRAIN SIZE ANALYSIS

Grain size analyses were performed on selected samples of granular soil in genera accordance

with ASTM D 422, Standard Method for Particle-Size Analysis of Soils. Results fthe grain

size analyses are plotted on grain size distribution curves presented in Figure B-1. Along with

each grain size distribution is a tabulated summary containing the sample descripti n (including

USCS symbol), percent passing the No. 200 sieve, and water content. Grain size istribution is

used to assist in classifying soils and to provide correlation with soil properties, in luding

permeability, capillarity, susceptibility to liquefaction, and sensitivity to moisture.

8.5 ATTERBERG LIMITS TESTS

Atterberg Limits tests were performed on one sample of fine-grained soil obtained in the borings

and in general accordance with ASTM D 4318, Standard Test Method for Liquid imit, Plastic

Limit, and Plasticity Index of Soils. The Atterberg Limits include Liquid Limit (L ), Plastic

Limit (PL), and Plasticity Index (LL- PL= Pl). They are generally used to assist ·n

classification of soils, indicate soil consistency (when compared with natural wate content), and

provide correlation to soil properties including compressibility and strength. The esults of the

Atterberg Limits determination are shown in the boring logs, and shown graphical y on the

plasticity chart presented in Figure B-2.

8.6 ORGANIC CONTENT

Organic content was determined on a sample of organic silty sand obtained in bori

test was conducted in general accordance with ASTM 02974, Standard Test Meth d for

Moisture, Ash, and Organic Matter of Peat and Other Organic Soils. Organic cont st is used to

assist in classification of soils and to provide correlation to soil properties includin

compressibility and strength. The result of the organic content determined is as fo lows:

USCS = Unified Soil Classification System

8.7 REFERENCE

ASTM International (ASTM), 2009, Annual book of standards, construction, v. 4. 8, soil and rock (I): D 420 - D 5876: West Conshohocken, Penn., ASTM Internationa, 1 v.

21-1-12294-001-RI-AB.docx/wp/lkn 21-1-12294-001

B-2

SIEVE ANALYSIS HYDROMETER ANALYSIS ~ SIZE OF MESH OPENING IN INCHES NO. OF MESH OPENINGS PER INCH, U.S. STANDARD GRAIN SIZE IN MILLIMETERS

. C

~ 0

~ ~ a:, :!l ;g ..,

§ ij C N - ;;'; ~ ~ ~ ~ 0 0 0 0 0 ~

.., N - 0 ~ ! - "' .,. .., N - - - ~ N .,.

"' - C! C! q q C! C! 100 - 0

\ ....... . - 1\ , ' '\. ~

" II. I

90 ' ' \ 1; y \ 10 i

'I. ' \ 1) \ \ \ ' !

' \

' \ ' 80 \ \ 20 !

\ \ ' \ \ I

I-I- 70 30 :r: i

I

:r: ' (!) I

(!) 'I. \ iii iii 'I. \ \ ~ ~ 60

'I. \ \ >- i

>- \ \ 40 co Ii co ' ' er er \ w w ' en z 50 ' ' er u:: " \ \ 50 <(

" \ \ 0

"' ~

I- " \ \ (.) z " \ \ I-w .., \ \ z (.) 40 er ' ' 60 w w ....... (.)

a. ........ \ .- er \ w

........ a. 30 - 70 -........

' 20 .... 80 ........

........ ....,

10 90

0 100

~ 0 ~ i !a 0 0 0 0 a:, "'

.,. .., N .... ~ U? "'. "1 "I ..-; ~ ~ ~ ~ N - 8 ~ ~ ., N & ~ ... .., N - C! C! ~ ~

GRAIN SIZE IN MILLIMETERS

COBBLES COARSE I FINE COARSE MEDIUM FINE

GRAVEL SAND I FINES: SILTORCLAY

BORING AND DEPTH u.s.c.s. SOIL LL PL Pl NAT. PASS. TEST CKD ASTM Black Creek Bridge No. 7 Replacement SAMPLE NO. (feet) SYMBOL CLASSIFICATION % % % W.C.% #200,% BY BY STND

e 8-1,S-5 12.5 SM Brown, silty, fine SAND 58.6 27.2 KMA JFL 0422 Grays Harbor County, Washington

• 8-1, S-11 32.5 SM Gray, silty, fine SAND, trace of clay 43.1 35.9 KMA JFL 0422

& 8-1, S-13 42.5 GM Gray, silty. sandy GRAVEL 14.8 12.9 KMA JFL 0422 GRAIN SIZE DISTRIBUTION BORING B-1

I

I August2009 21-1-12294-001

I SHANNON & WILSON, INC. I FIG. 8-1 . -landErwlronmontal Conoullanta

~ U> :,;

d 70

~ CL CH /

;: )>

LEGEND z ~

60 ;:; V "'

/ 'R

CL: Low plasticity inorganic G) ~

••···· ...... clays; sandy and silty U>

i ··•·· clays $ ,, z 50 . ' l7 CH: High plasticity inorganic ~

~ • clays ~ 0 ~ 0:: / ML or OL: Inorganic and organic silts ~ ' and clayey silts of low § X .

w 40 ; V . plasticity

C) - -.. ·-·-·· ··-- ----. .. . ..

~ .

' / MH or OH: Inorganic and organic silts

~ and clayey silts of high 0 plasticity i= .

~ 30 CL-ML: Silty clays and clayey slits

' ; c.. .. ..... --····---·" ·•· / ··~-- .. - ···-·-··-··- - ······ ...

/ 20

/ ···- / --~-- ,.

10 l,/': ·-f ' ''CL~ V ML<l rOL

....

MHc rOH .. . /

0 . .,,/' .

0 10 20 30 40 50 60 70 BO 90 100 110 NOTES LIQUID LIMIT· LL(%) AD Sample air dried before testing

ND Sample not air dried

RORINGAND DEPTH u.s.c.s. SOIL LL PL Pl NAT. PASS. TEST CKD SMPL "''--' ,...~-·- ..,_,_. __ .,_ "7 0-

SAMPLE NO. (feet) l>YMl:!UL CLASSIF1u.1,v,. -,. -,. -,. VV.<.;. 'To 1f.<W;,\ "BY tn ·=r. - - -~ ·-· - ..

ea-1. S-1s 52.5 CH Gray-brown, silty CLAY 66 19 47 21.7 AKV JFL ND Grays Harbor County, Washington

PLASTICITY CHART BORING B-1

'

I August2009 21-1-12294-001 .

I SHANNON & WILSON, INC. I Geottchnlcal and Environmental Consultants FIG. B-2

SHANNON t,WILSON, INC.

APPENDIXC

IMPORT ANT INFORMATION ABOUT YOUR GEOTECHNICAL REPORT

21-1-12294-001

-111 SHANNON & WILSON, INC. Geotechnical and Environmental Consultants

Attachment to and part of Report 21-1-12294-001

Date: S tember 16, 2009 To: H.W. Lochner Inc.

Attn: Mr. Al Kin

IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICALIENVI ONMENTAL REPORT

CONSULTING SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES AND FOR SPECIFIC CLIENTS.

Consultants prepare reports to meet the specific needs of specific individuals. A report prepared for a ci ii engineer may not be adequate for a construction contractor or even another civil engineer. Unless indicated otherwise, your consul t prepared your report expressly for you and expressly for the purposes you indicated. No one other than you should apply th' report for its intended purpose without first conferring with the consultant. No party should apply this report for any purpose ther than that originally contemplated without first conferring with the consultant.

THE CONSULTANT'S REPORT IS BASED ON PROJECT-SPECIFIC FACTORS.

A geotechnical/environmental report is based on a subsurface exploration plan designed to consider a uniq e set of project-specific factors. Depending on the project, these may include: the general nature of the structure and prope involved; its size and configuration; its historical use and practice; the location of the structure on the site and its orientation; oth r improvements such as access roads, parking lots, and underground utilities; and the additional risk created by scope-of-service Ii ·tations imposed by the client. To help avoid costly problems, ask the consultant to evaluate how any factors that change subsequen to the date of the report may affect the recommendations. Unless your consultant indicates otherwise, your report should not be use : (1) when the nature of the proposed project is changed (for example, if an office building will be erected instead of a parking g age, or if a refrigerated warehouse will be built instead of an unrefrigerated one, or chemicals are discovered on or near the site); (2) when the size, elevation, or configuration of the proposed project is altered; (3) when the location or orientation of the proposed proj ct is modified; (4) when there is a change of ownership; or (5) for application to an adjacent site. Consultants cannot accept respo ibility for problems that may occur if they are not consulted after factors which were considered in the development of the report have changed.

SUBSURFACE CONDITIONS CAN CHANGE.

Subsurface conditions may be affected as a result of natural processes or human activity. Because a geotec cal/environmental report is based on conditions that existed at the time of subsurface exploration, construction decisions should not be based on a report whose adequacy may have been affected by time. Ask the consultant to advise if additional tests are desirable befo e construction starts; for example, groundwater conditions commonly vary seasonally.

Construction operations at or adjacent to the site and natural events such as floods, earthquakes, or groundw er fluctuations may also affect subsurface conditions and, thus, the continuing adequacy of a geotechnical/environmental report. The onsultant should be kept apprised of any such events, and should be consulted to determine if additional tests are necessary.

MOST RECOMMENDATIONS ARE PROFESSIONAL JUDGMENTS.

Site exploration and testing identifies actual surface and subsurface conditions only at those points where pies are taken. The data were extrapolated by your consultant, who then applied judgment to render an opinion about overall subsurfa e conditions. The actual interface between materials may be far more gradual or abrupt than your report indicates. Actual conditions n areas not sampled may differ from those predicted in your report. While nothing can be done to prevent such situations, you and our consultant can work together to help reduce their impacts. Retaining your consultant to observe subsurface construction oper ions can be particularly beneficial in this respect.

Page I of2 1/2009

A REPORT'S CONCLUSIONS ARE PRELIMINARY.

The conclusions contained in your consultant's report are preliminary because they must be based on the assumption that conditions revealed through selective exploratory sampling are indicative of actual conditions throughout a site. Actual subsurface conditions can be discerned only during earthwork; therefore, you should retain your consultant to observe actual conditions and to provide conclusions. Only the consultant who prepared the report is fully familiar with the background information needed to determine whether or not the report's recommendations based on those conclusions are valid and whether or not the contractor is abiding by applicable recommendations. The consultant who developed your report cannot assume responsibility or liability for the adequacy of the report's recommendations if another party is retained to observe construction.

THE CONSULTANT'S REPORT IS SUBJECT TO MISINTERPRETATION.

Costly problems can occur when other design professionals develop their plans based on misinterpretation of a geotechnicaVenvironmental report. To help avoid these problems, the consultant should be retained to work with other project design professionals to explain relevant geotechnical, geological, hydro geological, and environmental findings, and to review the adequacy of their plans and specifications relative to these issues.

BORING LOGS AND/OR MONITORING WELL DATA SHOULD NOT BE SEPARATED FROM THE REPORT.

Final boring logs developed by the consultant are based upon interpretation of field logs (assembled by site personnel), field test results, and laboratory and/or office evaluation of field samples and data. Only final boring logs and data are customarily included in geotechnical/environmental reports. These final logs should not, under any circumstances, be redrawn for inclusion in architectural or other design drawings, because drafters may commit errors or omissions in the transfer process.

To reduce the likelihood of boring log or monitoring well misinterpretation, contractors should be given ready access to the complete geotechnical engineering/environmental report prepared or authorized for their use. If access is provided only to the report prepared for you, you should advise contractors of the report's limitations, assuming that a contractor was not one of the specific persons for whom the report was prepared, and that developing construction cost estimates was not one of the specific purposes for which it was prepared. While a contractor may gain important knowledge from a report prepared for another party, the contractor should discuss the report with your consultant and perform the additional or alternative work believed necessary to obtain the data specifically appropriate for construction cost estimating purposes. Some clients hold the mistaken impression that simply disclaiming responsibility for the accuracy of subsurface information always insulates them from attendant liability. Providing the best available information to contractors helps prevent costly construction problems and the adversarial attitudes that aggravate them to a disproportionate scale.

READ RESPONSIBILITY CLAUSES CLOSELY.

Because geotechnical/environmental engineering is based extensively on judgment and opinion, it is far less exact than other design disciplines. This situation has resulted in wholly unwarranted claims being lodged against consultants. To help prevent this problem, consultants have developed a number of clauses for use in their contracts, reports and other documents. These responsibility clauses are not exculpatory clauses designed to transfer the consultant's liabilities to other parties; rather, they are definitive clauses that identify where the consultant's responsibilities begin and end. Their use helps all parties involved recognize their individual responsibilities and take appropriate action. Some of these definitive clauses are likely to appear in your report, and you are encouraged to read them closely. Your consultant will be pleased to give full and frank answers to your questions.

The preceding paragraphs are based on information provided by the ASFE/Association of Engineering Firms Practicing in the Geosciences, Silver Spring, Maryland

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