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GEOTECHNICAL ENGINEERING REPORT

SNELL ROAD OVER MCCLURE DRAIN

OAKLAND TOWNSHIP

OAKLAND COUNTY, MICHIGAN

SME PROJECT NO. 076242.00

April 12, 2017

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TABLE OF CONTENTS

1. INTRODUCTION .................................................................................... 1

2. EVALUATION PROCEDURES .................................................................. 2

3. SUBSURFACE CONDITIONS .................................................................. 3

4. ANALYSIS AND RECOMMENDATIONS ................................................... 3

4.1 DESIGN CONSIDERATIONS AND PRELIMINARY GLOBAL STABILITY .......... 4

4.2 BOX CULVERT SUBGRADE PREPARATION AND BEDDING ........................... 5

4.3 WING WALL FOUNDATIONS ......................................................................... 6

4.4 VERIFYING SUITABLE BEARING SOILS DURING CONSTRUCTION ............... 6

4.5 CONSTRUCTION CONSIDERATIONS ............................................................. 7

APPENDIX: BORING LOG TERMINOLOGY

BORING LOGS (B1 AND B2)

PARTICLE SIZE DISTRIBUTION REPORT

PRELIMINARY SLOPE STABILITY ANALYSIS (FIGURES 1 AND 2)

LABORATORY TESTING PROCEDURES

GENERAL COMMENTS

IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL ENGINEERING

REPORT

13019 Pauline DriveShelby Township, MI 48315-3122

T (586) 731-3100

www.sme-usa.com

© 2017 SME 076242.00+041217+GER

April 12, 2017

Mr. Andrew T. Peters, PE, PTOE Road Commission for Oakland County 31001 Lahser Road Beverly Hills, Michigan 48025 Via e-mail: apeters@rcoc.org (PDF file) RE: Geotechnical Engineering Report

Snell Road over McClure Drain Oakland Township, Oakland County, Michigan

SME Project No. 076242.00 Dear Mr. Peters: SME has completed the geotechnical engineering evaluation for the proposed culvert replacement at Snell Road over McClure Drain. This report presents the results of our observations and analyses, and recommendations for design and construction of the new box culvert and wing wall foundations at the site. We appreciate the opportunity to assist the Road Commission for Oakland County (RCOC) with this project. If you have questions or comments regarding this report, we look forward to discussing the geotechnical considerations with RCOC. Sincerely,

SME Laurel M. Johnson, PE Senior Consultant

Report Written by: Report Reviewed by: Laurel M. Johnson, PE Melinda L. Bacon, PE Senior Consultant Senior Project Engineer

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1. INTRODUCTION

This report presents the results of the geotechnical evaluation for the proposed replacement of the existing culvert at Snell Road over the McClure Drain in Oakland Township, Oakland County, Michigan. The site is located north of Stony Creek Metropark, along the east side of a glacial moraine. Based on USGS data, McClure drain flows into Stony Creek Lake. Soil conditions in this area consist of a mixture of sands, silts, and clays over a relatively shallow extremely dense glacial till/hard clay till. Boulders and cobbles are often encountered overlying extremely dense glacial till/hard clay till. Organic soils are also common in low-lying areas adjacent to lakes, waterways and swamps. Based on available USGS Topographical Quadrangle maps (Figure 1 below), ground surface elevations in the area range from about elevation 810 feet to 825 feet.

FIGURE 1: USGS TOPOGRAPHIC QUADRANGLE MAP (EXCERPT)

Final culvert design details and plans are not available. However, the culvert will be either a precast concrete box culvert or a plate arch structure with a concrete apron/slab bottom. Span lengths of 8 to 12 feet are expected, and the culverts and wingwalls will be supported on shallow foundations. The culvert will have a width perpendicular to the roadway of about 35 to 40 feet.

Snell Road is currently a narrow, two-lane, two-way, gravel road, with a shoulder-to-shoulder width of about 28 feet, and a right-of-way width of 66 feet. Ground surface elevations were not provided, but based on our observations, the roadway at the crossing is between approximate elevations 810 and 812 feet, with the bottom of the drain about 6 to 8 feet below the road surface. At the time of drilling operations, SME measured the drain water surface to be about 5 to 6 feet below the road surface. The Road Commission for Oakland County (RCOC) did not provide SME with design flood water levels for this evaluation. However, SME estimated the 100-year flood levels may be at about elevation 809.2 feet based on an available FEMA flood map.

Site

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2. EVALUATION PROCEDURES

SME performed two borings (B1 and B2) near the existing culvert. RCOC determined the number and depths of the borings. SME located the borings in the field based on site accessibility and utility clearance. The borings were performed in the gravel shoulders of eastbound and westbound Snell Road. The approximate as-drilled boring locations are described on the upper portion of the boring logs included in the Appendix. Please refer to Figure 2 below, for a general schematic of the site (provided by RCOC) and the approximate as-drilled boring locations.

FIGURE 2: APPROXIMATE BORING LOCATIONS SME drilled the borings using a truck-mounted, rotary drill rig. The borings were advanced to the sampling depths using solid stem augers and soil sampling was performed based upon ASTM Standard D-1586 (Split-Barrel Sampling Procedure) along with Standard Penetration Testing (SPT) blow counts (N-values). The drillers recorded groundwater measurements during and immediately after completion of drilling operations. After completion of drilling activities, the boreholes were backfilled with a mixture of bentonite chips and auger cuttings. After backfilling, a drill hole plug was placed at the ground surface at each borehole location. The drillers sealed the recovered split-spoon samples in glass jars with lids in the field and returned the samples to SME’s soil laboratory for additional analyses. Laboratory testing included visual soil classification of recovered samples in general accordance with ASTM D2488. Moisture content tests and undrained shear strength (hand penetrometer tests) were also performed on portions of cohesive samples obtained. Additionally, moisture content test were performed on a portion of organic soil sample (peat) obtained. A particle size gradation analysis was performed on a soil sample recovered near the proposed bottom of culvert/bottom of wing wall elevation. The particle size gradation analysis results are plotted on the Material Test Report included in the Appendix. The appended Laboratory Testing Procedures provides general descriptions of the laboratory tests. Based on the laboratory testing and visual soil classification, a Unified Soil Classification System (USCS) symbol was assigned to the various soil strata encountered. A boring log was prepared for each boring that includes information on materials encountered, subsurface descriptions, penetration resistances, approximate location, pertinent field observations made during the drilling operations, and the results of the laboratory tests. An explanation of the symbols and terms used on boring logs is included on the Boring Log Terminology sheet included the Appendix. Soil samples retained over a long time, even in sealed jars, are subject to moisture loss and become no longer representative of the conditions initially encountered in the field. Therefore, soil samples are retained in our laboratory for 60 days after completion of the report and then disposed of, unless directed otherwise.

As-Drilled Location B2

As-Drilled Location B1

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3. SUBSURFACE CONDITIONS

Please refer to the appended boring logs for detailed descriptions of the subsurface conditions encountered at the specific boring locations. Stratification lines on the boring logs indicate a general transition between soil types. They are not intended to show an area of exact geological change. The soil description area is primarily based on visual classification of the soils encountered. Therefore, the actual USCS classification may be slightly different from the USCS soil types shown on the logs. The soil conditions encountered in the borings generally consist of 13 to 14 inches of a gravel/sand base material over sand fill extending about 4.5 to 5 feet below the existing road surface. Standard Penetration Test (SPT) resistances (N-values) obtained in the fill ranged from 4 to 12 blows per foot (bpf), indicating a very loose to medium dense condition. At boring B2, about 1-foot of peat was encountered beneath the fill extending from 4.5 to 5.5 feet below the existing road surface. The peat had a single moisture content of 49 percent indicating a compressive material. Very loose to medium dense natural sands were encountered in the borings beneath the sand fill and peat. The sands extended to a depth of about 17.5 feet at boring B1, and extended to the explored depth (25 feet) of boring B2. N-values obtained in the natural sands ranged from 4 to 24 bpf. Boring B2 was terminated in hard native clay. A single shear strength value of greater than 4.5 kips per square foot (ksf), and a single moisture content of 7 percent was obtained in the clay.

Groundwater was encountered in the borings at depths ranging between about 4.5 and 5.5 feet during drilling activities, and at depths ranging between about 5 to 6 feet after completion of drilling activities. The observed groundwater levels generally corresponded to the surface water level measured by SME during drilling operations in McClure Drain (between 5 and 6 feet below the existing road surface). Hydrostatic groundwater levels at this site will fluctuate throughout the year based primarily on the McClure Drain and Stony Creek Lake water levels. The groundwater levels indicated on the boring logs, and presented in this section, represent conditions at the time of drilling. The actual groundwater levels at the time of construction may vary.

4. ANALYSES AND RECOMMENDATIONS

The design of a culvert at a water crossing requires an understanding of potential watercourse scour (erosion) that could affect the structure. RCOC did not provide SME with 50 year and 100 year design flood elevations for this evaluation. Ground surface elevations were not provided, but based on our observations, the roadway at the crossing is between approximate elevations 810 and 812 feet, with the bottom of the drain about 6 to 8 feet below the road surface. SME estimated the 100-year flood design elevation at about 809.2 feet based on an available FEMA flood map depicted in Figure 3 on the following page.

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FIGURE 3: EXCERPT FROM FEMA FLOOD MAP (2006)

Scour information for the proposed structure was not available for use in the preparation of this report. SME anticipates a scour countermeasure system will be designed and constructed to protect the culvert from undermining during flood events. A particle size gradation analysis is included in the appendix to assist RCOC or others in determining scour depths at the proposed structure.

4.1 DESIGN CONSIDERATIONS AND PRELIMINARY GLOBAL STABILITY

SME used the geotechnical software, SLIDE, to simulate minimum cross sections for the soil and groundwater conditions encountered at the borings. AASHTO recommends a minimum geotechnical resistance factor for the apparent global stability shear surfaces of 0.65 (factor of safety of 1.54). SME used SLIDE to establish minimum bottom depth/bearing level of the culvert slab and wing wall foundations. The SLIDE configurations evaluated by SME are included in the appendix.

Based on preliminary slope stability analyses, and assuming the recommendations described in Section 4.2 of this report are properly implemented, the bottom of culvert slab elevation and bottom of wing wall footing elevation are proposed to be 799.5 feet and 798.5 feet, respectively (or about 10.5 and 11.5 feet, respectively below the existing road surface). These elevations assume a nominal elevation at the road surface of 810 feet. Peat was encountered at boring B2 between 4.5 and 5.5 feet below the existing road surface. The peat was most likely removed from beneath the existing culvert when it was constructed. Any remaining peat encountered within the culvert and wing wall footprints should be completely removed. On this basis, the culvert and wing wall foundations will bear on newly placed stabilized engineered fill or native very loose to loose sands beneath the peat. These soils are suitable for support of the culvert and wing wall foundations, although subgrade improvement at the time of construction will likely be required. We estimate the drain bottom elevation at about 802 feet (about 8 feet beneath the existing road surface), and the ordinary high water mark between elevations of about 804 and 805 feet (about 5 to 6 feet beneath the existing road surface). Therefore, we anticipate the contractor will likely encounter several feet of water during excavation activities for the placement of the bedding, the new culvert and the wing wall foundations.

We expect the contractor will temporarily divert the water flow in the outlet around the construction area using culverts, berms and ditches. The existing site sands are considered relatively permeable. Therefore, even with the diversion of the surface water, the contractor should expect relatively heavy groundwater seepage into the excavation for the removal and replacement of the culvert. The amount of

Approximate

Project Location

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seepage will vary depending on the time of year and the amount of precipitation and water runoff. Substantial dewatering of the construction area will be necessary to maintain relatively dry excavations for installation of the bedding, the culvert and the wing wall foundations. However, because the sands widely varied in grain size and in fines (silt and clay) content, dewatering using well points may be difficult.

The contractor is responsible for the means and methods of construction according the plans and MDOT Standard Specifications for Construction. The contractor may want to consider the use of a fully-enclosed, sheet pile type cofferdam with a tremie seal to limit the size of the excavation, control flow into the drain from the lake, and control groundwater seepage into the excavation during construction. If sheet piles are used, we recommend all sheeting located within 10 feet of the culvert ends be left in place. Extraction of sheeting could adversely affect the end sections. We expect the internal culvert segments and joints can tolerate removal of adjacent sheeting but the end segments and headers are sensitive. A licensed Professional Engineer working in conjunction with the contractor should design the temporary sheeting. Sheeting could also be left in place and used to counteract scour.

The contractor and the sheeting designer should be provided with historical information for the site, such as locations of previous and existing structures and utilities that may affect the construction and design of the sheeting or the installation of the new structure. If sheeting is used, care should be exercised during removal so as not to disturb the subsoil around and below the culvert.

4.2 BOX CULVERT SUBGRADE PREPARATION AND BEDDING

After diverting flow of the outlet or installing a fully-enclosed cofferdam with a tremie seal, and dewatering the excavation as necessary, the upper exposed bearing soils will likely be disturbed or unstable due to the construction activities. In accordance with the MDOT 2012 Standard Specifications for Construction 406.03.G.2, unstable/disturbed subsoils or obstructions other than bedrock should be undercut (removed) and replaced with or stabilized using a layer of MDOT 6A coarse aggregate modified with 80 percent crushed coarse aggregate. This layer should be a minimum of 12 inches thick, but may need to be thicker depending on the field conditions. The modified MDOT 6A coarse aggregate should be used as backfill in deeper excavations or placed over the entire unstable area. Remove any remaining peat, if encountered, within the culvert and wing wall zones of influence. For undercuts that extend beyond the outer edges of the culvert, the base of the undercut should be located beyond a 1:1 slope extended down from the outside bottom edge of the culvert to the base of the undercut. The MDOT 6A coarse aggregate should be placed in lifts not exceeding 12 inches and should be compacted or tamped/charged into the unstable subgrade with the backhoe bucket until the subgrade is sufficiently stable.

After stabilization of the bearing surfaces with the modified MDOT 6A aggregate, the final surface of the aggregate should be covered with 3 inches of MDOT 34R aggregate. However, if more than about 12 inches of modified MDOT 6A coarse aggregate is used to backfill undercuts, the top of the modified MDOT 6A should be choked with a dense graded aggregate (MDOT 21AA or 22A) or a suitable non-woven geotextile fabric prior to the placement of the MDOT 34R aggregate. The culvert bedding should extend at least 1 foot beyond the outside edges and ends of the culvert. The depth of the excavation for the culvert should allow for the recommended bedding layer and stabilization layer, if applicable.

Once the subgrade is prepared as described above, we anticipate the culvert can be placed directly on the aggregate bedding layer. Once the culvert is set and the position/elevations verified, the head walls or end sections can be constructed and the culvert backfilled.

We have assumed that culvert backfill (MDOT Class II, Class III or Class IIIA sand) placed to typical dimensions will be used adjacent to the culvert per the 2012 MDOT Standard Specifications for Construction. For compacted Class II Structure backfill, we recommend Rankine Lateral Earth Pressure Coefficients for an internal friction angle of 32 degrees be used for design. For level backfill conditions, use a Rankine Active Lateral Pressure Coefficient of 0.31 for the design of wing walls.

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4.3 WING WALL FOUNDATIONS

For foundations bearing on modified aggregate fill as described in Section 4.2, shallow foundations are feasible for support of the wing walls.

Based on the subsurface conditions, a factored bearing resistance of 2,750 pounds per square foot (psf) is available for wing wall footings. The final footing design must consider the eccentricity caused by moments and lateral shear loads applied to the footings from the proposed wing walls and shear keys that transfer load from the structures to the footings. We recommend that the resultant eccentricity be kept within the middle third of the footing width, i.e. a zero uplift condition for the footing edges.

A bearing resistance factor (φb) of 0.45 was used to determine the factored bearing resistance allowed for the strength limit state. We evaluated the serviceability limit states for an effective minimum footing width of 6 feet.

Settlement for the wing wall foundations is anticipated to be less than one-inch. We performed the bearing resistance and settlement analysis based on the methods described in the current edition of AASHTO LRFD Bridge Design Specifications.

4.4 VERIFYING SUITABLE BEARING SOILS DURING CONSTRUCTION

RCOC utilizes a dual mass sliding hammer dynamic cone penetrometer (DCP) probe to verify adequate bearing conditions. When evaluating bearing capacity or relative density, the single mass sliding unit (10.1 pound weight) should be used, and the number of blow counts per each 2-inch to 6-inch increment recorded. The number of blow counts observed are then evaluated based on relationships developed by the United States Army Corps of Engineers (USACE). A tabular summary of bearing capacity estimates based on blow counts is provided in the DCP user’s manual. For the clayey sands expected at the base of the excavation for this project, we recommend evaluating blow counts for each six-inch increment.

When evaluating bearing capacity, the differing terms used in LRFD design sometimes creates confusion. For non-LRFD projects, a criteria for “allowable bearing capacity” is typically provided. In LRFD terminology, the term “factored bearing resistance” is used in lieu of allowable bearing capacity. The factored bearing resistance is determined by applying an appropriate resistance factor (typically 0.35 to 0.45) to the “nominal bearing capacity”. Nominal bearing capacity can be compared to the non-LRFD term “ultimate bearing capacity”. The allowable bearing capacity is obtained by dividing the ultimate bearing capacity by an appropriate factor of safety, typically between 2.5 and 3 for shallow foundations. Therefore when evaluating the number of blow counts to verify bearing conditions for shallow foundations, the terms “factored bearing resistance” and “allowable (or design) bearing pressure” may be used interchangeably.

Based on empirical relationships between the expected bearing soils (fine clayey sands) and blow counts, a minimum blow count of 16 blows for six-inch increment is required for the single-mass hammer. A lower blow count in the upper 6 inches of no less than 10 can be accepted, provided a blow count of 16 blows is observed in the 6-to-12-inch increment, and blow counts are consistently above 16 blows in the two feet of soil immediately below the foundation bearing level. This allowable reduced blow count is based on SME’s experience with similar soil conditions.

The site sands, in combination with elevated water levels, are subject to subgrade disturbance during construction. Often, when overburden is removed, the resulting hydrostatic forces can result in an unstable subgrade condition. However, once a confining pressure is reestablished, an apparent increase in soil capacity is observed. To counteract this apparent temporary loosening of subgrade soils, verify targeted bearing soils are suitable for support of the structure prior to excavating to the design bearing

elevation. We recommend a minimum of 3 feet of overburden remain in place, which is

approximately equal to the overburden in place for foundations constructed at minimum frost

depth embedment (42 inches below final grades). If subgrade soils at the targeted bearing depth are unsuitably loose and are not suitable for support of the factored bearing resistance, improve the subgrade

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soils in-place by thoroughly compacting, or “charging” modified MDOT 6A into the subgrade at the foundation bearing level. This method of subgrade improvement is typically suitable where blow counts in the upper 2 feet indicate soils are suitable for support of factored bearing resistances of at least ¾ of the design factored bearing resistance (for this project, a minimum blow count of 10 to 11 blows per six-inch increment). As indicated previously, sandy soils, in combination with high groundwater levels can result in low blow counts at the time of testing. In most cases, subgrade improvement will be realized once the overburden is in place. For marginal blow counts, consider installing an open PVC pipe or other conduit adjacent to the foundation, and re-verify subgrade capacity at the bearing level by running the DCP through the PVC conduit once the foundation is in place.

Further, a minimum foundation width is provided based on preliminary slope stability analysis. The final foundation configuration may result in loads applied at the foundation bearing level that are less than the factored bearing resistance provided. Evaluate subgrade conditions for the lower contact pressure, if applicable.

If blow counts indicate the bearing soils are suitable for less than ¾ of the design factored resistance, undercut the subgrade soils 2 feet, extending undercuts outward 1 foot for each 2 feet of depth from the edge of the footing, charge modified MDOT 6A into the base of the excavation, backfill the excavation with modified MDOT 6A to the design foundation bearing level, and construct foundations at the design bearing level. By undercutting 2 feet and improving the subgrade at a depth of two feet, the effective pressure at the base of the improved subgrade, as applied by the foundation, is about 2,000 psf. This assumes the undercut is backfilled with aggregate and the foundation constructed at the design bearing elevation. Refer to the undercutting diagram below for additional information.

4.5 CONSTRUCTION CONSIDERATIONS

We recommend temporary construction slopes be graded no steeper than 2:1 (horizontal to vertical) due to the loose sands. Monitor the condition of any temporary slope utilized during construction for stability. In roadway widening areas (if any), depending on the specific conditions encountered during construction, require flatter slopes if needed. Since it is difficult to backfill on sloping ground, cut benches into the slope and place engineered backfill in level horizontal lifts not exceeding 9 inches in loose thickness. Backfill soils and compaction requirements should meet the specifications for bridge embankments provided by MDOT.

Foundation

Unsuitable Soils T= 2’ Max

Prepared Subgrade Charge Aggregate into Base of Excavation

Backfill to Design Bearing Elevation with MDOT 6A Modified

FIGURE 4: TYPICAL UNDERCUTTING DIAGRAM

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Slope, shore, or brace all slopes in accordance with MIOSHA requirements. The contractor should provide an adequately constructed and braced shoring system for employees working in an excavation that may expose employees to the danger of moving ground. If the contractor stores material or uses heavy equipment near the excavation, stronger shoring must be used to resist the increased pressure due to the superimposed loads. The contractor should take precautions to protect adjacent utilities, roadways, and structures during construction. The contractor must also provide for temporary diversion of the drain during construction, and protect the work area from flow (including flood conditions) during construction.

The global stability analysis we provide is preliminary until depth of scour and final culvert configuration is provided. Although not included in the current scope of services, SME can provide final stability analyses once detailed plans and scour depths are available.

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APPENDIX BORING LOG TERMINOLOGY

BORING LOGS (B1 AND B2)

PARTICLE SIZE DISTRIBUTION REPORT

PRELIMINARY SLOPE STABILITY ANALYSIS (FIGURES 1 AND 2)

LABORATORY TESTING PROCEDURES

GENERAL COMMENTS

IMPORTANT INFORMATION ABOUT YOUR GEOTECHNICAL ENGINEERING

REPORT

Determine percentages of sand and gravel from grain-size curve. Depending on percentage of fines (fraction smaller than No. 200 sieve size), coarse-grained soils are classified as follows:

Less than 5 percent……………………..……...GW, GP, SW, SP More than 12 percent……………………..…….GM, GC, SM, SC 5 to 12 percent……………...……..Cases requiring dual symbols

SP-SM or SW-SM (SAND with Silt or SAND with Silt and Grav-

el) SP-SC or SW-SC (SAND with Clay or SAND with Clay and

Gravel) GP-GM or GW-GM (GRAVEL with Silt or GRAVEL with Silt and

Sand) GP-GC or GW-GC (GRAVEL with Clay or GRAVEL with Clay

and Sand)

If the fines are CL-ML:

SC-SM (SILTY CLAYEY SAND or SILTY CLAYEY SAND with Gravel)

SM-SC (CLAYEY SILTY SAND or CLAYEY SILTY SAND with Gravel)

GC-GM (SILTY CLAYEY GRAVEL or SILTY CLAYEY GRAVEL with Sand)

GM-GC (CLAYEY SILTY GRAVEL or CLAYEY SILTY GRAVEL with Sand)

UNIFIED SOIL CLASSIFICATION AND SYMBOL CHART

COARSE-GRAINED SOIL (more than 50% of material is larger than No. 200 sieve size.)

GRAVEL

More than 50% of coarse

fraction larger than No. 4 sieve size

Clean Gravel (Less than 5% fines)

GW Well-graded gravel; gravel-sand mixtures, little or no fines

GP Poorly-graded gravel; gravel-sand mixtures, little or no fines

Gravel with fines (More than 12% fines)

GM Silty gravel; gravel-sand-silt mixtures

GC Clayey gravel; gravel-sand-clay mixtures

SAND

50% or more of coarse

fraction smaller than No. 4 sieve size

Clean Sand (Less than 5% fines)

SW Well-graded sand; sand-gravel mixtures, little or no fines

SP Poorly graded sand; sand-gravel mixtures, little or no fines

Sand with fines (More than 12% fines)

SM Silty sand; sand-silt-gravel mixtures

SC Clayey sand; sand–clay-gravel mixtures

FINE-GRAINED SOIL (50% or more of material is smaller than No. 200 sieve size)

SILT AND

CLAY Liquid limit less than

50%

ML Inorganic silt; sandy silt or gravelly silt with slight plasticity

CL Inorganic clay of low plasticity; lean clay, sandy clay, gravelly clay

OL Organic silt and organic clay of low plasticity

SILT AND

CLAY Liquid limit

50% or greater

MH Inorganic silt of high plasticity, elastic silt

CH Inorganic clay of high plasticity, fat clay

OH Organic silt and organic clay of high plasticity

HIGHLY ORGANIC

SOIL PT

Peat and other highly organic soil

LABORATORY CLASSIFICATION CRITERIA

GW D60 D30 CU = greater than 4; CC = between 1 and 3 D10 D10 x D60

GP Not meeting all gradation requirements for GW

GM Atterberg limits below “A” line or PI less than 4

Above “A” line with PI between 4 and 7 are borderline cases requiring use of dual symbols GC

Atterberg limits above “A” line with PI greater than 7

SW D60 D30 CU = greater than 6; CC = between 1 and 3 D10 D10 x D60

SP Not meeting all gradation requirements for SW

SM Atterberg limits below “A” line or PI less than 4 Above “A” line with PI

between 4 and 7 are borderline cases requiring use of dual symbols SC

Atterberg limits above “A” line with PI greater than 7

BORING LOG TERMINOLOGY

LIQUID LIMIT (LL) (%)

PLASTICITY CHART

DRILLING AND SAMPLING ABBREVIATIONS

2ST – Shelby Tube – 2” O.D. 3ST – Shelby Tube – 3” O.D. AS – Auger Sample GS – Grab Sample LS – Liner Sample NR – No Recovery PM – Pressure Meter RC – Rock Core diamond bit. NX size, except

where noted SB – Split Barrel Sample 1-3/8” I.D., 2” O.D.,

except where noted VS – Vane Shear WS – Wash Sample

OTHER ABBREVIATIONS

WOH – Weight of Hammer WOR – Weight of Rods SP – Soil Probe PID – Photo Ionization Device FID – Flame Ionization Device

PARTICLE SIZES

Boulders - Greater than 12 inches Cobbles - 3 inches to 12 inches Gravel- Coarse - 3/4 inches to 3 inches Fine - No. 4 to 3/4 inches Sand- Coarse - No. 10 to No. 4 Medium - No. 40 to No. 10 Fine - No. 200 to No. 40 Silt and Clay - Less than (0.0074 mm)

DEPOSITIONAL FEATURES

Parting – as much as 1/16 inch thick Seam – 1/16 inch to 1/2 inch thick Layer – 1/2 inch to 12 inches thick Stratum – greater than 12 inches thick Pocket – deposit of limited lateral extent Lens – lenticular deposit Hardpan/Till – an unstratified, consolidated or cemented

mixture of clay, silt, sand and/or gravel, the size/shape of the constituents vary widely

Lacustrine – soil deposited by lake water

Mottled – soil irregularly marked with spots of different

colors that vary in number and size

Varved – alternating partings or seams of silt and/or

clay

Occasional – one or less per foot of thickness Frequent – more than one per foot of thickness Interbedded – strata of soil or beds of rock lying between or

alternating with other strata of a different nature

VISUAL MANUAL PROCEDURE

When laboratory tests are not performed to confirm the classifica-tion of soils exhibiting borderline classifications, the two possible classifications would be separated with a slash, as follows:

For soils where it is difficult to distinguish if it is a coarse or fine-grained soil:

SC/CL (CLAYEY SAND to Sandy LEAN CLAY) SM/ML (SILTY SAND to SANDY SILT) GC/CL (CLAYEY GRAVEL to Gravelly LEAN CLAY) GM/ML (SILTY GRAVEL to Gravelly SILT)

For soils where it is difficult to distinguish if it is sand or gravel, poorly or well-graded sand or gravel; silt or clay; or plastic or non-plastic silt or clay:

SP/GP or SW/GW (SAND with Gravel to GRAVEL with Sand) SC/GC (CLAYEY SAND with Gravel to CLAYEY GRAVEL with

Sand) SM/GM (SILTY SAND with Gravel to SILTY GRAVEL with

Sand) SW/SP (SAND or SAND with Gravel) GP/GW (GRAVEL or GRAVEL with Sand) SC/SM (CLAYEY to SILTY SAND) GM/GC (SILTY to CLAYEY GRAVEL) CL/ML (SILTY CLAY) ML/CL (CLAYEY SILT) CH/MH (FAT CLAY to ELASTIC SILT) CL/CH (LEAN to FAT CLAY) MH/ML (ELASTIC SILT to SILT) OL/OH (ORGANIC SILT or ORGANIC CLAY)

OTHER MATERIAL SYMBOLS

Topsoil

Void

Sandstone

Asphalt

Glacial Till

Siltstone

Base

Coal

Limestone

Concrete

Shale

Fill

CLASSIFICATION TERMINOLOGY AND CORRELATIONS

Cohesionless Soils

Relative Density N-Value (Blows per foot)

Very Loose Loose Medium Dense Dense Very Dense Extremely Dense

0 to 4 4 to 10 10 to 30 30 to 50 50 to 80 Over 80

Standard Penetration ‘N-Value’ = Blows per foot of a 140-pound hammer falling 30 inches on a 2-inch O.D. split barrel sampler, except where noted.

Cohesive Soils

Consistency N-Value

(Blows per foot) Undrained Shear Strength (kips/ft2)

Very Soft Soft Medium Stiff Very Stiff Hard

0 - 2 2 - 4 4 - 8

8 - 15 15 - 30 > 30

0.25 or less 0.25 to 0.50

0.50 to 1.0

1.0 to 2.0

2.0 to 4.0

4.0 or greater

CL

PL

AS

TIC

ITY

IN

DE

X (

PI)

(%

)

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

10

60

50

40

30

20

CH

A LINE

PI=0.73 (LL-20)

MH & OH

ML & OL CL+ML

18

18

18

18

18

18

18

754

222

555

222

122

345

151820

1.2

5.0

7.5

14.0

17.5

20.0

14 inches of SAND and GRAVEL-Brown

FILL- Fine to Medium SAND with Silt,Clay, & Gravel- Occasional DecayedWood Pieces and Cobbles- Brown-Moist to Wet- Loose to Very Loose(SP-SM)

Fine to Medium SAND with Silt &Gravel- Gray- Wet- Medium Dense(SP-SM)

Fine to Medium CLAYEY SAND- LittleGravel- Gray- Wet- Very Loose (SC)

Fine to Medium SILTY SAND- Gray-Wet- Loose (SM)

LEAN CLAY with Sand- Gray- Hard(CL)

END OF BORING AT 20.0 FEET.

SB1

SB2

SB3

SB4

SB5

SB6

SB7

DATE STARTED: 3/29/17 COMPLETED: 3/29/17

LOGGED BY: CM CHECKED BY: LMJ

BORING METHOD: Solid-stem Augers

RIG NO.: 281DRILLER: RM

GROUNDWATER & BACKFILL INFORMATION NOTES: 1. The indicated stratification lines are approximate. In situ, the transition between materials may begradual.

5.0

DURING BORING:

AT END OF BORING:

4.5

MCPL LL

BACKFILL METHOD: Auger Cuttings and BentoniteChips with Hole Plug at Surface

DEPTH (FT)

REC

OVE

RY

LEN

GTH

(IN

CH

ES)

BORING B 1

BLO

WS

PER

SIX

INC

HES

N-VALUE --

10 20 30 40

PROJECT LOCATION: Oakland Township, Michigan

PROJECT NAME: Snell Road over McClure Drain PROJECT NUMBER: 076242.00

CLIENT: Road Commission for Oakland County

PAGE 1 OF 1

SY

MB

OLI

CP

RO

FIL

E STATION: Approximate: 18+25STREET: Snell RoadLANE: Eastbound Shoulder PROFILE DESCRIPTION

DRY DENSITY(pcf) --

90 100 110 120

MOISTURE &ATTERBERGLIMITS (%)

10 20 30 40

TRIAXIAL (UU)

HAND PENE.

VANE SHEAR (REM)

UNC.COMP.

REMARKS

SHEARSTRENGTH (KSF)

1 2 3 4

TORVANE SHEAR

VANE SHEAR (PK)

SAM

PLE

TYPE

/NO

.IN

TER

VAL

DE

PT

H (

FE

ET

)

9

4

10

4

4

9

38 7 4.5+

0

5

10

15

20

18

10

18

18

16

18

18

1375

511

222

222

223

357

5816

1.1

4.5

5.5

8.0

13.5

20.0

13 inches of Fine to Coarse SANDand GRAVEL- Brown

FILL- Fine to Medium SILTY SANDwith Gravel- Brown & Dark Brown-Moist- Medium Dense to Loose (SM)

Amorphic PEAT with Sand- Black(PT)

Fine CLAYEY SAND- Brown- Wet-Very Loose (SC)

Fine CLAYEY SAND- Gray- Wet-Very Loose to Loose (SC)

Fine to Medium SAND with Silt &Gravel- Occasional Sandy Lean ClayLayers and Seams- Gray- Wet-Medium Dense (SP-SM)

END OF BORING AT 20.0 FEET.

SB1

SB2

SB3

SB4

SB5

SB6

SB7

DATE STARTED: 3/29/17 COMPLETED: 3/29/17

LOGGED BY: CM CHECKED BY: LMJ

BORING METHOD: Solid-stem Augers

RIG NO.: 281DRILLER: RM

GROUNDWATER & BACKFILL INFORMATION NOTES: 1. The indicated stratification lines are approximate. In situ, the transition between materials may begradual.

6.0

DURING BORING:

AT END OF BORING:

5.5

MCPL LL

BACKFILL METHOD: Auger Cuttings and BentoniteChips with Hole Plug at Surface

DEPTH (FT)

REC

OVE

RY

LEN

GTH

(IN

CH

ES)

BORING B 2

BLO

WS

PER

SIX

INC

HES

N-VALUE --

10 20 30 40

PROJECT LOCATION: Oakland Township, Michigan

PROJECT NAME: Snell Road over McClure Drain PROJECT NUMBER: 076242.00

CLIENT: Road Commission for Oakland County

PAGE 1 OF 1

SY

MB

OLI

CP

RO

FIL

E STATION: Approximate: 18+75STREET: Snell RoadLANE: Westbound Shoulder PROFILE DESCRIPTION

DRY DENSITY(pcf) --

90 100 110 120

MOISTURE &ATTERBERGLIMITS (%)

10 20 30 40

TRIAXIAL (UU)

HAND PENE.

VANE SHEAR (REM)

UNC.COMP.

REMARKS

SHEARSTRENGTH (KSF)

1 2 3 4

TORVANE SHEAR

VANE SHEAR (PK)

SAM

PLE

TYPE

/NO

.IN

TER

VAL

DE

PT

H (

FE

ET

)

12

2

4

4

5

12

24

49

0

5

10

15

20

82.1No.1676.9No.3065.0No.50

87.9No.899.53/8in93.3No.4

% PassingSieve Size Limits

17.9Finer No.200 (75µm)39.1No.10020.5No.200

Date Tested: 4/7/2017

F/M Clayey Sand- Little Gravel- GrayMaterialNo Gradation SpecificationSpecification

Sample Details17-4287-S1Sample IDApr 7, 2017Date Sampled

1Bore Hole7.5' - 12.5'Depth

Sampled By

Sample Description:F/M Clayey Sand- Little Gravel- Gray

Grading:

1.6632D85: 0.2623D60: 0.2008D50:0.1069D30: N/AD15: N/AD10:

ASTM C 136, ASTM C 117Particle Size Distribution

COBBLES GRAVELCoarse(0.0%)

Fine(6.7%)

SANDCoarse (6.7%)

Medium (15.6%)

Fine (50.5%)

FINES (20.5%)Silt Clay

(0.0%)

This report represents conditions at specific locations, therefore, conditions might vary away fromthose locations. No one except our client may rely on our findings/opinions, or reproduce this report.SME is not responsible for site safety on this project.

Material Test Report MAT:17-4287-S1-1Client:

Reviewed By:

Project: RCOC Culvert ReplacementsRoad Commission of Oakland

South Blvd W of John R & SnellOakland Township MI 00000

Laurel M. Johnson, PE

CC:

13019 Pauline DriveShelby Twp, MI 48315-3122

(586) 731-3100www.sme-usa.com

Report No.:Project No.: 076242.00

Contractor:

Page 1 of 1© 2000-2013 QESTLab by SpectraQEST.comForm No: 18909, Report No: MAT:17-4287-S1

1.5591.559

W

360.00 lbs/ft2

1.5591.559

Elevation 810.0 ft

Minimum Bottom of Culvert Elevation 799.5 ft

Snell Road over McClure DrainOakland Township, MichiganSME Project No. 076242.00

Sliding Block Failure AnalysisDrained ConditionsRemove Peat from Beneath Culvert and Wingwalls

Minimum Culvert Base Elevation 799.5 ft.Meets Minimum Stability Requirements forNormal Water Conditions

Very Loose to Loose SandsUnit Weight: 120 lb/ft3Friction Angle: 28 degrees

Hard ClayUnit Weight: 135 lb/ft3Cohesion: 150 psfFriction Angle: 34 degrees Medium Dense Sands

Unit Weight: 120 lb/ft3Friction Angle: 32 degrees

Embankment FillUnit Weight: 120 lb/ft3Friction Angle: 32 degrees

PeatUnit Weight: 65 lb/ft3Cohesion: 5 psfFriction Angle: 10 degrees

30 ft +/-

Culvert

66 ft +/-

Concrete Wingwalls

Average Water Level 803 ft

86

08

40

82

08

00

78

0

40 60 80 100 120 140 160 180

Analysis DescriptionSnell Road over McClure Drain

CompanySME

Scale1:185

Drawn ByLaurel M. Johnson, PE

File NameSnell Road.slmd

Date4/5/2017, 4:57:30 PM

Project

SLIDE - An Interactive Slope Stability Program

SLIDEINTERPRET 7.020

1.7041.704

W

360.00 lbs/ft2

1.7041.704

Snell Road over McClure DrainOakland Township, MichiganSME Project No. 076242.00

Sliding Block Failure AnalysisDrained ConditionsRemove Peat from Beneath Culvertand Wingwalls

Minimum Culvert Base Elevation 799.5 ftMeets Minimum Stability Requirements forHigh Water Elevation 809.2 ft

Note: Assumes adequate slope armoring and rip rap is placed for slope and scour protection.

30 ft +/-

66 ft +/-

Very Loose to Loose SandsUnit Weight: 120 lb/ft3Friction Angle: 28 degrees

Medium Dense SandsUnit Weight: 120 lb/ft3Friction Angle: 32 degrees Hard Clay

Unit Weight: 135 lb/ft3Cohesion: 150 psfFriction Angle: 34 degrees

PeatUnit Weight: 65 lb/ft3

Concrete Wingwalls

Embankment FillUnit Weight: 120 lb/ft3Friction Angle: 32 degrees

Culvert

84

08

20

80

07

80

50 60 70 80 90 100 110 120 130 140 150 160 170

Analysis DescriptionSnell Road over McClure Drain

CompanySME

Scale1:155

Drawn ByLaurel M. Johnson, PE

File NameSnell Road.slmd

Date4/5/2017, 4:57:30 PM

Project

SLIDE - An Interactive Slope Stability Program

SLIDEINTERPRET 7.020

© 2009 SME Laboratory Testing Procedures 1

LABORATORY TESTING PROCEDURES VISUAL ENGINEERING CLASSIFICATION Visual classification was performed on recovered samples. The appended General Notes and Unified Soil Classification System (USCS) sheets include a brief summary of the general method used visually classify the soil and assign an appropriate USCS group symbol. The estimated group symbol, according to the USCS, is shown in parentheses following the textural description of the various strata on the boring logs appended to this report. The soil descriptions developed from visual classifications are sometimes modified to reflect the results of laboratory testing.

MOISTURE CONTENT Moisture content tests were performed by weighing samples from the field at their in-situ moisture condition. These samples were then dried at a constant temperature (approximately 110º C) overnight in an oven. After drying, the samples were weighed to determine the dry weight of the sample and the weight of the water that was expelled during drying. The moisture content of the specimen is expressed as a percent and is the weight of the water compared to the dry weight of the specimen.

HAND PENETROMETER TESTS In the hand penetrometer test, the unconfined compressive strength of a cohesive soil sample is estimated by measuring the resistance of the sample to the penetration of a small calibrated, spring-loaded cylinder. The maximum capacity of the penetrometer is 4.5 tons per square-foot (tsf). Theoretically, the undrained shear strength of the cohesive sample is one-half the unconfined compressive strength. The undrained shear strength (based on the hand penetrometer test) presented on the boring logs is reported in units of kips per square-foot (ksf).

TORVANE SHEAR TESTS In the Torvane test, the shear strength of a low strength, cohesive soil sample is estimated by measuring the resistance of the sample to a torque applied through vanes inserted into the sample. The undrained shear strength of the samples is measured from the maximum torque required to shear the sample and is reported in units of kips per square-foot (ksf).

LOSS-ON-IGNITION (ORGANIC CONTENT) TESTS Loss-on-ignition (LOI) tests are conducted by first weighing the sample and then heating the sample to dry the moisture from the sample (in the same manner as determining the moisture content of the soil). The sample is then re-weighed to determine the dry weight and then heated for 4 hours in a muffle furnace at a high temperature (approximately 440º C). After cooling, the sample is re-weighed to calculate the amount of ash remaining, which in turn is used to determine the amount of organic matter burned from the original dry sample. The organic matter content of the specimen is expressed as a percent compared to the dry weight of the sample.

ATTERBERG LIMITS TESTS Atterberg limits tests consist of two components. The plastic limit of a cohesive sample is determined by rolling the sample into a thread and the plastic limit is the moisture content where a 1/8-inch thread begins to crumble. The liquid limit is determined by placing a ½-inch thick soil pat into the liquid limits cup and using a grooving tool to divide the soil pat in half. The cup is then tapped on the base of the liquid limits device using a crank handle. The number of drops of the cup to close the gap formed by the grooving tool ½ inch is recorded along with the corresponding moisture content of the sample. This procedure is repeated several times at different moisture contents and a graph of moisture content and the corresponding number of blows is plotted. The liquid limit is defined as the moisture content at a nominal 25 drops of the cup. From this test, the plasticity index can be determined by subtracting the plastic limit from the liquid limit.

© 2009 SME General Comments 1

GENERAL COMMENTS BASIS OF GEOTECHNICAL REPORT This report has been prepared in accordance with generally accepted geotechnical engineering practices to assist in the design and/or evaluation of this project. If the project plans, design criteria, and other project information referenced in this report and utilized by SME to prepare our recommendations are changed, the conclusions and recommendations contained in this report are not considered valid unless the changes are reviewed, and the conclusions and recommendations of this report are modified or approved in writing by our office. The discussions and recommendations submitted in this report are based on the available project information, described in this report, and the geotechnical data obtained from the field exploration at the locations indicated in the report. Variations in the soil and groundwater conditions commonly occur between or away from sampling locations. The nature and extent of the variations may not become evident until the time of construction. If significant variations are observed during construction, SME should be contacted to reevaluate the recommendations of this report. SME should be retained to continue our services through construction to observe and evaluate the actual subsurface conditions relative to the recommendations made in this report. In the process of obtaining and testing samples and preparing this report, procedures are followed that represent reasonable and accepted practice in the field of soil and foundation engineering. Specifically, field logs are prepared during the field exploration that describe field occurrences, sampling locations, and other information. Samples obtained in the field are frequently subjected to additional testing and reclassification in the laboratory and differences may exist between the field logs and the report logs. The engineer preparing the report reviews the field logs, laboratory classifications, and test data and then prepares the report logs. Our recommendations are based on the contents of the report logs and the information contained therein.

REVIEW OF DESIGN DETAILS, PLANS, AND SPECIFICATIONS SME should be retained to review the design details, project plans, and specifications to verify those documents are consistent with the recommendations contained in this report.

REVIEW OF REPORT INFORMATION WITH PROJECT TEAM Implementation of our recommendations may affect the design, construction, and performance of the proposed improvements, along with the potential inherent risks involved with the proposed construction. The client and key members of the design team, including SME, should discuss the issues covered in this report so that the issues are understood and applied in a manner consistent with the owner’s budget, tolerance of risk, and expectations for performance and maintenance.

FIELD VERIFICATION OF GEOTECHNICAL CONDITIONS SME should be retained to verify the recommendations of this report are properly implemented during construction. This may avoid misinterpretation of our recommendations by other parties and will allow us to review and modify our recommendations if variations in the site subsurface conditions are encountered.

PROJECT INFORMATION FOR CONTRACTOR This report and any future addenda or other reports regarding this site should be made available to prospective contractors prior to submitting their proposals for their information only and to supply them with facts relative to the subsurface evaluation and laboratory test results. If the selected contractor encounters subsurface conditions during construction, which differ from those presented in this report, the contractor should promptly describe the nature and extent of the differing conditions in writing and SME should be notified so that we can verify those conditions. The construction contract should include provisions for dealing with differing conditions and contingency funds should be reserved for potential problems during earthwork and foundation construction. We would be pleased to assist you in developing the contract provisions based on our experience. The contractor should be prepared to handle environmental conditions encountered at this site, which may affect the excavation, removal, or disposal of soil; dewatering of excavations; and health and safety of workers. Any Environmental Assessment reports prepared for this site should be made available for review by bidders and the successful contractor.

THIRD PARTY RELIANCE/REUSE OF THIS REPORT This report has been prepared solely for the use of our Client for the project specifically described in this report. This report cannot be relied upon by other parties not involved in the project, unless specifically allowed by SME in writing. SME also is not responsible for the interpretation by other parties of the geotechnical data and the recommendations provided herein.

Geotechnical-Engineering Report

Geotechnical Services Are Performed for Specific Purposes, Persons, and ProjectsGeotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a civil engineer may not fulfill the needs of a constructor — a construction contractor — or even another civil engineer. Because each geotechnical- engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. No one except you should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one — not even you — should apply this report for any purpose or project except the one originally contemplated.

Read the Full ReportSerious problems have occurred because those relying on a geotechnical-engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only.

Geotechnical Engineers Base Each Report on a Unique Set of Project-Specific FactorsGeotechnical engineers consider many unique, project-specific factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk-management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates otherwise, do not rely on a geotechnical-engineering report that was:• not prepared for you;• not prepared for your project;• not prepared for the specific site explored; or• completed before important project changes were made.

Typical changes that can erode the reliability of an existing geotechnical-engineering report include those that affect: • the function of the proposed structure, as when it’s changed

from a parking garage to an office building, or from a light-industrial plant to a refrigerated warehouse;

• the elevation, configuration, location, orientation, or weight of the proposed structure;

• the composition of the design team; or• project ownership.

As a general rule, always inform your geotechnical engineer of project changes—even minor ones—and request an

assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed.

Subsurface Conditions Can ChangeA geotechnical-engineering report is based on conditions that existed at the time the geotechnical engineer performed the study. Do not rely on a geotechnical-engineering report whose adequacy may have been affected by: the passage of time; man-made events, such as construction on or adjacent to the site; or natural events, such as floods, droughts, earthquakes, or groundwater fluctuations. Contact the geotechnical engineer before applying this report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems.

Most Geotechnical Findings Are Professional OpinionsSite exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ — sometimes significantly — from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide geotechnical-construction observation is the most effective method of managing the risks associated with unanticipated conditions.

A Report’s Recommendations Are Not FinalDo not overrely on the confirmation-dependent recommendations included in your report. Confirmation-dependent recommendations are not final, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report’s confirmation-dependent recommendations if that engineer does not perform the geotechnical-construction observation required to confirm the recommendations’ applicability.

A Geotechnical-Engineering Report Is Subject to MisinterpretationOther design-team members’ misinterpretation of geotechnical-engineering reports has resulted in costly

Important Information about This

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

While you cannot eliminate all such risks, you can manage them. The following information is provided to help.

problems. Confront that risk by having your geo technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and specifications. Constructors can also misinterpret a geotechnical-engineering report. Confront that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing geotechnical construction observation.

Do Not Redraw the Engineer’s LogsGeotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical-engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk.

Give Constructors a Complete Report and GuidanceSome owners and design professionals mistakenly believe they can make constructors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation. To help prevent costly problems, give constructors the complete geotechnical-engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise constructors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited; encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure constructors have sufficient time to perform additional study. Only then might you be in a position to give constructors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions.

Read Responsibility Provisions CloselySome clients, design professionals, and constructors fail to recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help

others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.

Environmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical-engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk-management guidance. Do not rely on an environmental report prepared for someone else.

Obtain Professional Assistance To Deal with MoldDiverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces. To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold-prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, many mold- prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical- engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold prevention consultant; none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved.

Rely, on Your GBC-Member Geotechnical Engineer for Additional AssistanceMembership in the Geotechnical Business Council of the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you GBC-Member geotechnical engineer for more information.

8811 Colesville Road/Suite G106, Silver Spring, MD 20910Telephone: 301/565-2733 Facsimile: 301/589-2017

e-mail: info@geoprofessional.org www.geoprofessional.org

Copyright 2015 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, or its contents, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document

is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document as a complement to or as an element of a geotechnical-engineering report. Any other firm, individual, or other entity that so uses this document without

being a GBA member could be commiting negligent or intentional (fraudulent) misrepresentation.