751-17154TAP_SewerUpgradeGeotechnical_04-14-2021 (1)_Part1.pdf

856 E. Eighth Street, Suite 1 Traverse City, MI 49686-2784

T (231) 941-5200 www.sme-usa.com

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April 14, 2021

Mr. David E. Richmond, PE ROWE Professional Services Company 504 South Saginaw Street, Suite 200 Flint, Michigan 48502

Via Email: DRichmond@rowepsc.com (PDF file)

RE: Geotechnical Evaluation Aloha State Park Sanitary Improvements Aloha Township, Cheboygan County, Michigan SME Project No. 086011.00

Dear Mr. Richmond:

SME has completed the geotechnical evaluation for the proposed sanitary sewer improvements at Aloha State Park in Aloha Township, Cheboygan County, Michigan. This report presents the results of our observations and analyses, our geotechnical recommendations, and general construction considerations based on the information disclosed by the borings.

This evaluation was conducted in general accordance with the scope of services outlined in SME Proposal No. P00100.21 dated January 8, 2021; however, an additional 5 feet of drilling was performed at boring B5 to extend the boring through very soft natural clays. ROWE Professional Services Company (ROWE) authorized our services.

As input into our evaluation, ROWE provided SME with a plan set titled “Construction Plans for Michigan Department of Natural Resources Aloha State Park – Sewer System Upgrades” dated January 2021.

SITE CONDITIONS AND PROJECT DESCRIPTION

The overall project site is located at the Aloha State Park along Park Road, south of Center Street, on the eastern shore of Mullett Lake. The specific site locations are depicted on the Location Map insets contained on the attached Boring Location Diagrams (Figure Nos. 1 through 5). The overall site includes campsites, restrooms, and associated paved drives.

The project will consist of the design and construction of new sanitary sewer piping, water piping, three pump stations, and a grinder pump vault. The sanitary piping will be installed with a minimum 4 feet of cover and the water piping will be installed with a minimum 3 feet of cover. However, based on the referenced plans, we anticipate the piping will be installed deeper than the minimum but generally not more than 11 feet below existing grades. The gravity sewer portion of the piping will be installed with open-cut trench construction. The sanitary force main and water piping may be installed using horizontal directional drilling (HDD) methods.

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Two pump stations will have a depth of about 20 feet beneath existing grades, and will be located near project STA 12+50 and 36+00. One pump station will have a depth of about 12 feet beneath existing grade, and will be located near project STA 19+00. The grinder vault will have a depth of about 8 feet beneath final grades, and will be located near project STA 43+00.

EVALUATION PROCEDURES

FIELD EXPLORATION

SME completed nine (9) borings (B1 through B9) at the site on February 17, 2021. The borings extended to between 10 and 30 feet beneath the existing ground surface. The approximate as-drilled locations of the borings are shown on Figure Nos. 1 through 5.

ROWE determined the planned number and locations of the borings. SME determined the depths of the borings. SME located the borings in the field by measuring from existing site features. SME estimated the existing ground surface elevations at the boring to the nearest 1-foot based on topographic information included on the referenced plan set.

The borings were performed with a rotary drill rig and were advanced to the sampling depths using continuous-flight augers. The borings included soil sampling based upon the Split-barrel Sampling Procedure. Recovered split-barrel samples were sealed in glass jars by the driller.

Groundwater observations were recorded during and upon completion of drilling. Upon completion of drilling, the boreholes were backfilled with auger cuttings.

Soil samples recovered from the field exploration were returned to the SME laboratory for further observation and testing.

LABORATORY TESTING

The laboratory testing program consisted of performing visual soil classification on recovered samples in general accordance with ASTM D2488. Moisture content and hand penetrometer or torvane shear tests were performed on portions of cohesive samples. Moisture content and torvane shear tests were also performed on organic soils. The attached Laboratory Testing Procedures provides descriptions of these laboratory tests. Based on the laboratory testing, we assigned a Unified Soil Classification System (USCS) group symbol to the each of the various soil strata encountered.

Upon completion of the laboratory testing, boring logs were prepared that include information on materials encountered, penetration resistances, and pertinent field observations made during the drilling operations, along with the results of the laboratory tests. Each log also includes the existing ground surface elevation as estimated by SME. The boring logs are attached to this report. Explanations of symbols and terms used on the boring logs are provided on the attached Boring Log Terminology sheet.

Soil samples are normally retained in our laboratory for 60 days and then dispose of them, unless instructed otherwise.

SUBSURFACE CONDITIONS

SOIL CONDITIONS

The soil conditions encountered at the boring locations generally consisted of surficial topsoil (except at boring B2) underlain by natural sands, silts, and clays that generally extended to the explored depths of the borings. However, existing sand fill was encountered at borings B3, B5, B6, B7, and B9 and

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extended about 1 to 3.5 feet beneath the existing ground surface, corresponding to approximate elevations 594.5 to 600 feet. In addition, organic soils (i.e. peat, mostly silt, or mostly clay) were encountered at borings B3, B7, and B9 and extended about 3.5 to 8.5 feet beneath the existing ground surface, corresponding to approximate elevations 592.5 to 594.5 feet.

The existing sand fill was encountered in a very loose to loose condition, and contained peat seams in boring B9. The organic soils had moisture contents between about 30 and 306 percent. The natural sands were encountered in a very loose to dense condition, and contained peat seams in borings B5, B6, and B8. The natural clays and cohesive silts had moisture contents between 25 and 39 percent and exhibited very soft to very stiff consistencies, however, a majority of those soils exhibited very soft to stiff consistencies.

The soil profile included on the boring logs is a generalized description of the conditions encountered.

The stratification depths described above and shown on the boring logs indicate a zone of transition from one soil type to another and do not show exact depths of change from one soil type to another. Soil conditions may vary between and away from the boring locations from those conditions noted on the boring logs.

GROUNDWATER CONDITIONS

Groundwater was encountered in the borings at about 1 to 6 feet beneath the existing ground surface during drilling, which corresponds to approximate elevations 594.5 to 600 feet. Upon completion of drilling, groundwater was observed in the boreholes at borings B2 through B9 about 3 to 7 feet beneath the existing ground surface, which corresponds to approximate elevations 591 to 598 feet. Groundwater was not observed above the borehole cave-in depth after removing augers from boring B1.

In cohesive soils (clays and silts) and organic soils, a long time may be required for the groundwater level in the borehole to reach an equilibrium position. Therefore, the use of groundwater observation wells (piezometers) is necessary to accurately determine the hydrostatic groundwater level within cohesive and organic soils as encountered predominately throughout the site.

Hydrostatic groundwater levels and groundwater seepage rates encountered in excavations should be expected to fluctuate throughout the year, based on variations in precipitation, evaporation, run-off, the level of the Mullett Lake, and other factors. The groundwater observations indicated on the boring logs, and presented in this section, represent conditions at the time the readings were taken. The groundwater levels at the time of construction may vary from those conditions noted on the logs.

ANALYSIS AND RECOMMENDATIONS

GROUNDWATER CONSIDERATIONS

Based on the referenced plan set, the water level within the boat basin that connects to Mullet lake was about elevation 594 feet at the time of the survey. We anticipate long-term groundwater levels at the site will be at or slightly above the water level of Mullet lake. However, perched groundwater conditions should be anticipated above that elevation.

Based on the borings, the water level of Mullett Lake, and the proposed invert depths of the proposed gravity sewer, pump stations, and grinder vault, excavations for these improvements will extend as much as about 19 feet below the groundwater level encountered at the borings. The excavations will extend through sands for the proposed gravity sewer, grinder vault, and pump station near borings B1 and B2 in the northern portion of the site. The excavations for the pump stations and gravity sewer near borings B4 and B7 will extend through sands and organics in some areas and into clays.

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We anticipate high capacity dewatering techniques (e.g. well points or pumps in slotted casings) will be required to temporarily lower the groundwater level within the proposed gravity sewer excavations.

Closed cofferdams will be required for the pump stations and possibly the grinder vault excavation. For the pump station and grinder vault near borings B1 and B2 in the northern portion of the site, a tremie seal will be required within the cofferdam to control groundwater in the sands. For the pump stations near borings B4 and B7, cofferdams will extend into clay and we do not anticipate a tremie seal will be required; however, a tremie seal may be required for the excavation of the pump station near boring B7 due to the recommended undercutting of the very soft clays as discussed below.

The selected groundwater dewatering system should temporarily lower the groundwater level at least 1 foot below the bottom of excavations. The dewatering system should remain in operation until construction is sufficiently above the site groundwater levels and provisions to combat buoyancy effects are in-place.

The pump stations and grinder vault will need to be designed to resist uplift loads due to buoyancy since the site groundwater levels post construction are anticipated to be above the bottom of the structures.

The critical case will be when the vaults are empty and the site groundwater levels are highest.

Resistance to uplift or buoyancy effects could be provided by extending the bottom mat beyond the edges of the vaults, by installing anchorages within the mat that provide tensile resistance to uplift forces, or a combination of these methods. Design considerations for buoyancy effects are described in the Below- Grade Walls section of this report.

GRAVITY SEWER PIPING

The improvements will include the installation of a new 8-inch diameter gravity sewer at the south end of the project and 6-inch and 8-inch gravity sewer at the north end of the project. The new sewer pipe will be situated with a minimum of 4 feet of cover. However, based on the referenced plan set, the sewer will extend as much as about 11 feet beneath existing ground surface levels.

Based on the borings, we anticipate clays will typically be encountered near the sewer invert level at the southern portion of the site. We anticipate sands will typically be encountered near the sewer invert level at the northern portion of the site. However, organic soils were encountered at borings B3 and B9 that extended about to elevation 592.5 feet. The referenced plan set shows a proposed invert level of about 596 feet near boring B3. A proposed invert elevation for the gravity sewer near boring B9 was not provided. Organic soils must be undercut from below the new sanitary sewer.

Low strength natural clays and silts with high moisture contents could be encountered at the proposed invert levels in the vicinity of borings B4 through B7. The contractor should be prepared to place a layer sand over any wet, disturbed, or low-strength clay subgrade to provide a stable base for the sewer piping.

Based on the shallow groundwater levels, we do not anticipate open cut excavations will be feasible along the majority of the trench alignment. In areas where adequate side slopes or benching are not feasible, due to depth, site constraints, groundwater conditions, or proximity of existing structures, the excavation sidewalls must be supported with internally braced sheeting or trench boxes. If material is stored or equipment is operated near an excavation, stronger shoring must be used to resist the extra pressure due to the superimposed loads.

As indicated above, we anticipate high capacity dewatering techniques (e.g. well points or pumps in slotted casings) will be required to temporarily lower the groundwater level within the proposed gravity sewer excavations near borings B1 and B2. Where the sewer excavation extends more than about 1 foot beneath the groundwater level in sands, high capacity dewatering techniques such as well-points or cased wells will be required.

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The pipe bedding detail (materials, placement and compaction) should conform to the requirements of the entity having jurisdiction. In our experience, pipe bedding is usually a relatively clean granular material placed and compacted to a minimum of 12 inches above the pipe crown.

ENGINEERED FILL REQUIREMENTS

Fill placed within the construction area, including utility trench backfill, should be an approved material, free of frozen soil, organics, particle sizes that will hinder compaction, construction debris, or other deleterious materials. Fill placed in structural areas should be compacted to a minimum of 95 percent of the maximum dry density as determined in accordance with the Modified Proctor test. The fill should be spread in level layers not exceeding 9 inches in loose thickness. Sand fill should be compacted with a smooth-drum vibratory roller or vibratory plate compactors, including either walk-behind types or plate compactors mounted on a backhoe or excavator (hoe-pac).

Based on the information from the borings, most of the existing sand fill and some of the natural sands (with USCS designations “SP” or “SP-SM”) are considered suitable for reuse as engineered fill, provided it meets the requirements of the previous paragraph. The silty sands (with USCS designation “SM”) are difficult to compact in confined areas, and other areas where compaction is accomplished primarily by hand-operated equipment. Based on the borings, the sand fill and upper natural sands with USCS group symbol “SM”, as well as silts, clays, or organics, should not be used as engineered fill. SME should verify the suitability of on-site sands proposed for reuse in confined areas by performing gradation analyses.

Imported fill should meet the requirements of MDOT Class II Granular Material. Unsuitable site soils should be placed in non-structural areas of the site or hauled off site.

For stabilizing subgrades, we recommend using MDOT 6A aggregate. The aggregate should be compacted using by tamping the layers using a backhoe or excavator bucket, if the material is placed in trenches or other confined areas. The crushed aggregate should be compacted until it is stable. If a granular material is proposed for placement above the crushed aggregate, then the crushed aggregate should be choked with a layer of at least 6 inches of dense-graded aggregate such as MDOT 21AA, or covered by a non-woven geotextile separator fabric per the MDOT Standards Specification for Construction, prior to placement of the granular material.

PUMP STATION AND VAULT SUPPORT

Precast mat foundations will be used for support of the proposed pump station and grinder vaults. Based on the borings, medium dense to dense natural sands are anticipated to be encountered at the bottom of the pump station and grinder vault near borings B1 and B2. Medium dense to dense natural sands are suitable for support of the pump station and grinder vault. We anticipate natural clays or silts will be encountered at the bottom of the excavations for the pump stations located near borings B4 and B7.

Near boring B7, and possibly near boring B4, the clay and silt present at the bottom of the proposed excavations is very soft with high moisture contents. Very soft natural clays and silts with high moisture contents are prone to severe disturbance and are therefore not suitable for support of the pumps stations.

Near boring B4, the very soft clays and silts extended to about elevation 587 feet. Near boring B7, the very soft clays extended to about elevation 569.5 feet. We recommend undercutting these soils from beneath the proposed pumps station vaults and replacing the soils with MDOT 6A aggregate.

Since a tremie seal will be required in the cofferdam for the pump station near boring B2 and likely near boring B7, an 8-inch thick layer of 6A aggregate can be used for bedding beneath the pumps station at these locations. The depth of the excavation for the mat foundations should account for the recommended thickness of aggregate subbase. The aggregate subbase should extend laterally at least 1 foot beyond the outside edges of the mat foundations. The aggregate subbase should be compacted with vibratory plate compactors in accordance with the Engineered Fill Requirements section below.

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BELOW-GRADE WALLS

The walls for the proposed pump stations and grind vault will extend as much as about 20 feet below the final ground surface. The below-grade walls should be backfilled with granular soils meeting the requirements of MDOT Class II granular material. Groundwater levels in the absence of temporary construction dewatering are expected to remain well above design bottom levels of the mat foundations.

Dewatering on a permanent basis is generally not considered practical for the structures, and we anticipate the below-grade walls and foundations will be designed to resist both lateral earth pressures, and hydrostatic forces associated with local groundwater levels at this site.

For the purpose of designing the below-grade walls of the vaults, we recommend a design groundwater level that is at the existing ground surface to account for periods of high groundwater and perched conditions.

The design of the below-grade walls of the tanks must consider the effect of the design groundwater level. For below-grade walls below the design groundwater level and a level finish surface behind the wall, we recommend a combined lateral earth and hydrostatic (water) of 90 pcf for design for the at-rest earth pressure condition. Any additional lateral wall loads resulting from surcharge loading, and stockpiled materials, should also be added to the above earth pressures.

Hydrostatic uplift pressures due to the effects of buoyancy created by placement of the structures below the groundwater level should also be addressed in design of the walls and foundation. The weight of the below-grade structures, in combination with extending foundations beyond the walls (to utilize the weight of the overlying subgrade soils) may be used to resist uplift. If the mat foundations are extended laterally wider than the tanks, provided the mats are stiff enough, we recommend computing the weight of soil directly above the lateral foundation extension to resist uplift, and using a bouyant unit weight of 50 pcf for properly placed fill compacted to at least 90 percent of the maximum dry density as determined in accordance with the Modified Proctor test below the design groundwater level. Resistance to hydrostatic uplift should be computed for the worst-case condition when the tanks are empty. If additional resistance to uplift is needed, either the mat foundation can be thickened, extended further laterally as described above, or tie-downs (such as piles) may be extended below the mat foundations of the tanks. If desired, SME can assist with the design of a tie-down foundations system or further review whether an additional wedge of soil extending outside the mat foundation perimeter can be considered for resistance to uplift, based on the specific backfill materials used and specific foundation configurations.

HDD CONSIDERATIONS

The sanitary force main and water piping will likely be installed using HDD methods. Based on the borings, the use of HDD methods should be feasible for this purpose, assuming the contractor exercises care during the drilling operations. However, the existing subsurface conditions include the presence of permeable granular soils, clays of variable strength, weak organic soils, and relatively shallow groundwater levels, which must be considered when planning and executing the work. Prior to final design, the proposed pipeline invert elevations should be reviewed and modified, as needed, to facilitate feasible and economical completion of the HDD operations.

Organic soils are often encountered in variable conditions due to the nature in which they were deposited.

As such, it would be difficult to predict how they would behave if/where encountered during HDD boring operations. If the proposed alignment were to extend through the encountered organic soils, it would likely be difficulty to maintain steering control during the pilot bore and there is also a high risk of hydrofracture. As such, we do not recommend proposed drill alignment extend through organic soils.

The proposed alignment should be lowered to avoid these soil conditions within these areas.

Appropriate drilling fluid pressures must be maintained during HDD boring activities since either excessive or inadequate drilling fluid pressure can cause disturbance and strength loss in soils surrounding the HDD borehole. Drilling mud returns should be monitored so changes to the drilling mud

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mix design can be made as the bore alignment encounters varying soil conditions. The encountered granular soils should be considered to be relatively permeable and will likely require a different drilling fluid composition and pressure required to maintain a suitable borehole condition compared to the encountered natural clays.

The HDD contractor must consider factors, such as drilling fluid pressure, the consistency of the drilling fluid, borehole alignment, rate of borehole advancement, amount of over-bore, the length of time the borehole is unsupported, and the existing soil conditions so the bore can be advanced without disturbing the surrounding soil or causing distress to the overlying ground surface or adjacent utilities.

Based on the anticipate shallow depth, open-cut methods should be feasible to excavate the entry and exit pits for the proposed HDD, assuming the pit locations are offset sufficiently from adjacent utilities and infrastructure to allow adequately sloped excavations that remain within the existing easement. If construction operations are such that a sufficient set-back for sloping and benching of an open-cut excavation cannot be accommodated, a temporary earth retention system (TERS) will be required.

Earthwork and the excavation for pits should comply with the local requirements, which should be verified prior to the development of the final project plans.

Groundwater may be encountered near the ground surface at the proposed entry and exit pit locations.

The earthwork and dewatering contractors typically design the necessary earth retention and dewatering systems for their construction operations, as these means and methods may vary from contractor to contractor. Successful contractor(s) must submit earth retention and dewatering plans, as needed, which are prepared by licensed professional engineers experienced with those applications. SME can review contractor submittals, provide additional recommendations, and help the design team, as needed, if requested.

CONSTRUCTION CONSIDERATIONS

As indicated above, high capacity dewatering techniques will be required to temporarily lower site groundwater levels in excavations that extend more than about 1 foot below the groundwater level sands.

Closed cofferdams will be required to facilitate dewatering for construction of the pump stations, and possibly the grinder vault. Where the cofferdams terminate in sands, tremie seals will be required within the cofferdams.

Dewatering systems should be designed and installed by a qualified contractor experienced in the installation of dewatering systems. The contractor should submit the proposed dewatering plan prior to construction, for review by the engineer. The plan should include approximate locations and number of wells or wellpoints to be used, along with construction details of the wells or wellpoints and estimated pumping rates and drawdown limits. Installation of groundwater level observation wells should be considered to verify the soil conditions, and the drawdown of the groundwater levels, adjacent to critical structures. Design of dewatering systems for this project should include an evaluation of the potential effect of the anticipated groundwater drawdown on adjacent structures. The contractor should be required to employ and demonstrate methods to resist “sanding” or loss of fine soils from around the wells, and provide monitoring of sanding using meters made for that purpose or other techniques such as diverting flow into a large barrel (usually a 50-gallon drum) to check for sand content. An evaluation of the potential settlement that could result from increased effective stress related to lowering the groundwater level should also be performed.

We expect excavations will extend to within about 1-foot of the site groundwater levels after the site is sufficiently dewatered on a temporary basis. Operating compaction equipment near the groundwater level in sands can cause “quick” conditions. If this occurs, the compaction of engineered fill should be performed using static methods until the fill placement extends sufficiently above the site groundwater level.

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The contractor must take precautions to protect adjacent existing structures and utilities during construction of the new structures. Care must be exercised during the excavating and compacting operations so that excessive vibrations do not cause settlement of the existing structures and utilities, and avoid undermining existing foundations or utilities during excavation for new foundations. Where sufficient space or setback from existing utilities or structures exists, we anticipate the sides of the excavation can be temporarily sloped back in accordance with applicable regulations, or flatter as required for stability of the materials encountered. However, in areas where sufficient setback cannot be maintained, temporary earth retention systems (TERS) will be required during construction. Where new foundations adjoin existing foundations, the new foundations should not extend below the level of the existing footings without underpinning of the existing footings. Underpinning should be properly designed by a qualified professional engineer, and installed by a contractor experienced with construction of underpinning systems.

We recommend the bid documents include “base bid” requirements for excavation to anticipated suitable soils, and then a requirement that prospective contractors include unit prices for undercutting/excavating organic soils below the “base bid” depths, if necessary. Unit prices should also be obtained for backfill using imported engineered fill (MDOT Class II granular material), dense graded aggregate (MDOT 21AA), and MDOT 6A aggregate.

The contractor must provide a safely-sloped excavation or an adequately constructed and braced shoring system in accordance with federal, state and local safety regulations for individuals working in an excavation that may expose them to the danger of moving ground. If material is stored or heavy equipment is operated near an excavation, stronger shoring must be used to resist the extra pressure due to the superimposed loads. The contractor must provide a safely-sloped excavation or an adequately constructed and braced shoring system in accordance with federal, state, and local safety regulations for individuals working in an excavation that may expose them to the danger of moving ground. If material is stored or heavy equipment is operated near an excavation, use appropriate shoring to resist the extra pressure due to the superimposed loads.

Handling, transportation, and disposal of excavated materials and groundwater should be performed in accordance with applicable regulations.

We appreciate the opportunity to be of service. If you have questions regarding this report or if you require additional information, please contact us.

Sincerely, SME

Prepared By: Reviewed By:

Paul E. Anderson, PE Andrew T. Bolton, PE Senior Project Engineer Senior Consultant

Attachments: Boring Location Diagrams (Figure Nos. 1 through 5) Boring Log Terminology Boring Logs (B1 through B9) General Comments Laboratory Testing Procedures Important Information About This 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)

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

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

Gravel with fines (More than 12% fines)

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 symbolsGC 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 symbolsSC 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)

OTHER MATERIAL SYMBOLS

Topsoil Void Sandstone

Asphalt Glacial Till Siltstone

Base Coal Limestone

Concrete Shale Fill

CLASSIFICATION TERMINOLOGY AND CORRELATIONS

Cohesionless Soils

Relative Density N60 (N-Value) (Blows per foot)

Very Loose Loose Medium Dense Dense Very Dense Extremely Dense

0 to 4 5 to 10 11 to 30 31 to 50 51 to 80 Over 81

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. N60 values as reported on boring logs represent raw N-values corrected for hammer efficiency only.

Cohesive Soils

Consistency N60 (N-Value) (Blows per foot)

Undrained Shear Strength (kips/ft2)

Very Soft Soft Medium Stiff Very Stiff Hard

<2 2 - 4 5 - 8

9 - 15 16 - 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

P L

A S

T

IC

IT

Y

IN

D

E X

(P I)

0 10 20 30 40 50 60 70 80 90 100

CH

A LINE

PI=0.73 (LL-20)

MH & OH

ML & OLCL+ML

DESCRIPTION OF RELATIVE QUANTITIES

The visual-manual procedure uses the following terms to describe the relative quantities of notable foreign materials, gravel, sand or fines:

Trace – particles are present but estimated to be less than 5% Few – 5 to 10% Little – 15 to 25% Some – 30 to 45% Mostly – 50 to 100%

© 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.

© 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.