Geotechnical Report - Sikeston Substation.pdf

Geotechnical Engineering Services Report

Sikeston Substation

Sikeston, Missouri

Prepared for

Fisher & Arnold, Inc.

9180 Crestwyn Hills Drive

Memphis, TN 38125

Prepared by

Professional Service Industries, Inc.

4161 Ridgemoor Avenue Memphis, Tennessee 38118

January 7, 2014

PSI Project No.: 0502928

Sikeston Substation January 7, 2014

TABLE OF CONTENTS

1.0 PROJECT INFORMATION

1.1 PROJECT AUTHORIZATION

1.2 PROJECT DESCRIPTION

1.3 PURPOSE AND SCOPE OF SERVICES

2.0 SITE AND SUBSURFACE CONDITIONS

2.1 SITE LOCATION AND DESCRIPTION

2.2 SITE GEOLOGY

2.3 SEISMICITY

2.4 SUBSURFACE MATERIALS

2.5 GROUNDWATER INFORMATION

3.0 EVALUATION AND RECOMMENDATIONS

3.1 GEOTECHNICAL DISCUSSION

3.2 SITE PREPARATION

3.3 FILL REQUIREMENTS

3.4 FOUNDATION RECOMMENDATIONS

3.5 EARTH PRESSURE

3.6 SITE CLASS

4.0 CONSTRUCTION CONSIDERATIONS

4.1 MOISTURE SENSITIVE SOILS/WEATHER RELATED CONCERNS

4.2 DRAINAGE AND GROUNDWATER CONSIDERATIONS

4.3 EXCAVATIONS

5.0 REPORT LIMITATIONS

APPENDIX - Boring Location General Notes Boring Logs

1.0 PROJECT INFORMATION

1.1 PROJECT AUTHORIZATION

Professional Service Industries, Inc. (PSI) has completed a geotechnical exploration for the proposed additions to an existing electrical substation in Sikeston, Missouri. Our services were authorized by October 28, 2013 by Mr. George Mellen of Fisher & Arnold on behalf of Southwest Power Association (SWPA). This exploration was accomplished in general accordance with PSI Proposal No. 0502-106030, dated September 27, 2013.

1.2 PROJECT DESCRIPTION

Project information was obtained from Mr. Mellen of Fisher & Arnold, Inc. PSI has also been furnished with a drawing titled ‘Sikeston Substation’, dated October 2013. The proposed construction will consist of the installation of new equipment at the existing facility. Detailed structural loading information has not been provided; however, based on past experience, PSI has based this proposal on the following:

Component Pvertical (kips) Hhorizontal (kips) Mr (ft-kips) 161kV Bus 4.0 1.0 20.0 161kV Switch Stand 8.0 1.0 50.0 12kV Tension Dead-End 12.0 8.0 230.

161kV Tension Dead-End 9.0 10.0 150.0 Transformer Pad 120.0 1.0 --

PSI is basing this report on mat foundations being utilized. No below ground construction is planned to our knowledge. Since grading plans have not been provided at this time, the magnitude of cuts and fills on the site cannot be determined. However, PSI is basing this report on that less than two feet of cut or fill will be required to achieve design grade. We have based this report on the proposed facility being constructed in accordance with the provisions of the International Building Code, 2012.

The geotechnical recommendations presented in this report are based on the available project information, structure locations, and the subsurface materials described in this report. If the noted information is incorrect, please inform PSI in writing so that we may amend the recommendations presented in this report if appropriate and if desired by the client. PSI will not be responsible for the implementation of its recommendations when it is not notified of changes in the project.

1.3 PURPOSE AND SCOPE OF SERVICES

The purpose of this study was to explore the subsurface conditions at the site to enable an evaluation of acceptable foundation systems for the proposed facility. Our scope of services included drilling ten (10) soil test borings at the site to depths of about 10 feet below the surface, select laboratory testing, and preparation of this geotechnical report.

This report briefly outlines the testing procedures, presents available project information, describes the site and subsurface conditions, and presents recommendations regarding the following:

• A discussion of subsurface conditions encountered including pertinent soil properties and groundwater conditions.

• Geotechnical related recommendations for foundation design based on the encountered soils and proposed building construction.

• An evaluation of foundation settlements.

• Recommendations for overall site/soil preparation, including natural in-place soil and fill and overall suitability of the in-situ soils for use as utility backfill and structural fill.

• Discussions on geotechnical issues that may impact the planned construction activities.

The scope of services for this geotechnical study did not include an environmental assessment for determining the presence or absence of wetlands or hazardous or toxic materials in the soil, bedrock, surface water, groundwater, or air, on or below or around this site. Any statements in this report or on the boring logs regarding odors, colors or unusual or suspicious items or conditions are strictly for the information of the client.

As directed by the client, PSI did not provide any service to investigate or detect the presence of moisture, mold or other biological contaminates in or around any structure, or any service that was designed or intended to prevent or lower the risk of the occurrence of the amplification of the same. Client acknowledges that mold is ubiquitous to the environment with mold amplification occurring when building materials are impacted by moisture. Client further acknowledges that site conditions are outside of PSI’s control, and that mold amplification will likely occur, or continue to occur, in the presence of moisture.

As such, PSI cannot and shall not be held responsible for the occurrence or recurrence of mold amplification.

2.0 SITE AND SUBSURFACE CONDITIONS

2.1 SITE LOCATION AND DESCRIPTION

The project site is located along CR-478 in Sikeston, Missouri. At the time of drilling operations, the site was observed to be an existing substation development. The site was generally level and grass covered.

2.2 SITE GEOLOGY

Sikeston, Missouri lies in a physiographic subdivision known as the Alluvial Plain and is included in a portion of the Section called the Mississippi Embayment. The Embayment is a bell-shaped arm of the Gulf of Mexico outlined roughly by Little Rock, Arkansas on the west; Cairo, Illinois on the north; and the Lower Tennessee River on the east.

2.3 SEISMICITY

Sikeston, Missouri is in the general proximity of New Madrid, Missouri, the epicenter for some of the largest earthquakes in the North American continent. Four earthquakes of about magnitude 7.3 to 8 centered near New Madrid, Missouri occurred during the winter of 1811-1812. Presently, the New Madrid area contains the highest level of seismicity in the central and eastern parts of the United States. Our scope of services did not include a liquefaction study.

Data obtained from Google data server (http://www.googleearth.com), indicated that the approximate site latitude and longitude are 36°52’35.44” N and 89°37’30.48” W, respectively. Using this information and the USGS Earthquake Hazards Program information (http://earthquake.usgs.gov/research/hazmaps) and the requirements of IBC 2012, the project site has a mapped 0.2 second spectral response acceleration (Ss) of approximately 2.342g and a mapped 1.0 second spectral response acceleration (S1) of approximately 0.861g.

2.4 SUBSURFACE MATERIALS

The site subsurface conditions were explored with ten (10) soil test borings drilled at the substation facility. The borings were advanced to depths of about 10 feet. The boring locations and depths were selected by Fisher & Arnold, Inc., and the boring locations are illustrated on the Boring Location Plan enclosed in Appendix I. The borings were located in the field by PSI personnel by measuring distances from known site features using a 100 foot tape. Topographic and grading information was not provided. PSI recommends that ground surface elevations at the borings be determined and provided to us for review along with the site grading plan, as it may impact our design recommendations.

The borings were advanced utilizing hollow stem auger drilling methods, and soil samples were routinely obtained during the drilling process. Drilling and sampling techniques were accomplished generally in accordance with ASTM procedures. The PSI General Notes for soil borings are enclosed in Appendix II and the boring logs are in Appendix III. Select soil samples were tested in the laboratory to determine material properties for our evaluation.

Laboratory testing was accomplished generally in accordance with ASTM procedures.

http://www.googleearth.com/

Approximately 1½ to 3½ feet of materials identified as undocumented fill was encountered at the ground surface in Borings B-1, B-2, B-3, and B-6. This material generally consisted of a clay with trace pieces of crushed stone.

The soils encountered at the borings beneath the organic and undocumented fill materials may be divided into two general strata. The upper stratum consisted of predominantly fine-grained soils and the second stratum consisted of sandy soils. These soil strata are discussed separately below.

The upper stratum of predominantly fine-grained soil extended from the organic and undocumented fill materials to depths ranging from about 4 to 9 feet at the boring locations. Based on results of visual classification, these soils were classified as sandy high plasticity clay (CH or “fat” clay) in accordance with the USCS. Standard penetration N-values within these fine-grained soils generally indicated consistencies of firm to stiff;

however, soils with a soft consistency were encountered at depths of 4 to 5½ feet in Boring B-1 and B-4, and about 2 to 3½ feet in Boring B-10. Overall, the moisture content of the fine-grained soil varied from 16 to 39 percent. These fine-grained soils were moist to relatively wet.

The second stratum consisted of sandy soils that extended to the boring terminal depths.

Based on visual classification, these soils were classified as clayey sand (SC) or poorly graded sand (SP) in accordance with the USCS. Standard penetration N-values within these granular soils generally indicated the materials to be medium dense to very dense;

however, loose sandy soils were encountered at depths of about 7 to 8½ feet in Boring B- 3, 0 to 1½ feet in Boring B-5.

The above subsurface description is of a generalized nature to highlight the major subsurface stratification features and material characteristics. The boring logs in the appendix should be reviewed for specific information at individual boring locations. These records include soil descriptions, stratifications, penetration resistances, locations of the samples, and laboratory test data. The stratifications shown on the boring logs represent the conditions only at the actual boring locations. Variations may occur and should be expected between boring locations. The stratifications represent the approximate boundary between subsurface materials and the actual transition may be gradual. Water level information obtained during field operations is also shown on these boring logs. The samples that were not altered by laboratory testing will be retained for 60 days from the date of this report and then will be discarded.

2.5 GROUNDWATER INFORMATION

Observations were made to determine if groundwater was present in the borings during drilling and at completion of drilling. During drilling operations, groundwater was measured at depths ranging from 7 to 8 feet in 5 of the 10 borings. After completion of drilling, groundwater was not encountered. Saturated soils were encountered near the ground surface. Some fluctuations of the groundwater level should be anticipated with changing climatic conditions. The groundwater information presented in this report was obtained at the time of drilling, but the groundwater level at the site may be different at the time of construction.

3.0 EVALUATION AND RECOMMENDATIONS

3.1 GEOTECHNICAL DISCUSSION

The available subsurface data when considered in conjunction with the structural information indicates that conventional mat type foundations may be used to support the proposed structural. This is based on the site being developed in accordance with the recommendations presented in this report. Difficult site preparation should be anticipated due to the presence of soils with soft consistencies which will require remediation and may retard construction activities. Further, high plasticity (“fat”) clay was encountered. PSI recommends that the fat clays be kept at least 2 feet below design subgrade elevation.

Any exposed fat clays should be maintained near or slightly above optimum moisture during construction. Excessive wetting or drying of the fat clays during construction may result in settlement or heaving after construction is completed. The volume changes of the fat clays are caused by changes in the moisture content. For this reason, we recommend that soils be compacted and maintained throughout construction at their optimum moisture content or slightly above.

Consideration must be given to the existing facilities that will be demolished during site development operations. It is possible that soils in some areas have been disturbed through past construction activities. Further, poorly compacted existing fills may exist in some areas. We have not been provided with any plans showing the existing foundation layout or foundation systems. If plans are located for the existing structures, PSI requests that we be allowed to review them. Once this is accomplished, a methodology for removal and replacement can be developed. It is common to use different subcontractors in this area for demolition and grading. Thus, it is necessary to closely monitor the preparation, backfill, and compaction of areas disturbed by demolition. Excavations should not be “covered up” without proper backfilling as this may result in unsatisfactory performance of the new construction.

3.2 SITE PREPARATION

We recommend that topsoil, existing undocumented fill materials, and any soft soils in the construction areas be stripped from the site. The depth of topsoil removal and the adequacy of stripping operations should be determined by a representative of the geotechnical engineer at the time of construction. Since the site has been developed, some zones of rubble or other unsuitable materials may have been buried during the earlier construction. Should any such materials be encountered, they should also be removed.

Existing utilities should be located and rerouted as necessary and any pipes or utility conduits should be removed. Utility trench excavations must be cut to competent bearing soils suitable for support of fill placement and then backfilled with properly compacted fill that is constructed as outlined in of this report.

After stripping and excavating to the proposed subgrade level, as required, the construction areas should be proof-rolled with a moderately heavy pneumatic-tired vehicle such as a loaded tandem axle dump truck or similar rubber tired vehicle (9 ton/axle).

Alternatively, proof-compaction may be used with a light to medium weight compacter.

Soils that are observed to rut or deflect excessively under the moving load, or are otherwise judged to be unsuitable, should either be processed and re-compacted or undercut and replaced with properly compacted fill. The decision as to the most appropriate method of remedial action where problems are encountered should be made by the geotechnical engineer based on the site conditions at the time of construction. The proof-rolling and undercutting operations should be witnessed by the geotechnical engineer and should be performed during a period of dry weather.

The subgrade soils should be scarified and compacted to at least 95 percent of the standard Proctor (ASTM D 698) maximum dry density for a depth of at least 6 inches below the surface. If fill is required, the structural fill should then be placed on the prepared subgrade.

Groundwater was measured at depths as shallow as 7 to 8 feet in 5 of the 10 borings. It may be necessary for the contractor to deal with saturated soils and/or seepage during some site preparation operations. Some dewatering operations may be required to allow work to proceed (e.g., excavation of utility trenches, undercutting, etc.).

Some relatively wet fine-grained soils were encountered in the borings. Fine-grained soils that have moisture contents more than about 2 to 3 percentage points above the optimum moisture are generally prone to softening when dynamic loads such as those generated by the wheels of construction equipment are imposed upon them even if the soils exhibited substantial strength in an undisturbed state. After disturbance, these wet fine-grained soils typically rut and deflect significantly and do not provide adequate subgrade support for floor slabs, foundations, or fill placement. The presence of relatively wet fine-grained soils may require activities such as aeration, drying, and re-compaction or undercutting. These marginal strength soils are in addition to the soft soils previously discussed. In addition, it will probably be necessary to process cut soils to obtain a suitable moisture content if it is desired to re-use these materials as fill.

If desired, bulk samples of the site soils may be obtained by PSI for standard Proctor tests to help define the optimum moisture contents of site soils. Based on these test results, more definitive statements can be made regarding the necessity to undercut, aerate and re-compact wet fine-grained soil subgrades and the level of effort that will likely be required to adjust the moisture content of the in-situ soils that will be cut and used for fill.

Past experience indicates that these earthwork operations may be time consuming and have the potential to add considerable cost to the earthwork portion of the project.

We note that implementing good site management techniques can reduce potential undercut requirements. These techniques include improving and maintaining site drainage throughout construction and limiting site traffic during periods of wet soil conditions.

It is common for construction equipment to severely disturb the upper several feet of the subgrade during initial phases of site earthwork operations, especially if site preparation work is performed while the soils are wet. This may result in the need for either deep undercutting and replacement of the disturbed soils or drying and re-compaction of the affected soils. The owner may want to consider an allowance in the budget to cover this condition. This is of even greater concern if site preparation operations will be conducted during periods of the year with typically high rainfall amounts.

It is anticipated that the moisture content and strength characteristics of the upper soils may be adequately improved via processing and recompaction. However, should the contractor have difficulty in obtaining the required subgrade support due to inclement weather or a fast track construction schedule, consideration may be given to subgrade stabilization via the use of lime or cement. These materials can also be used to lower the moisture content of wet borrow soils. A specialty contractor will have to be retained if these methods are to be used, and laboratory tests will have to be conducted to determine if either cement or lime will be beneficial in stabilization of the soils. Additional recommendations will be required from the geotechnical engineer during construction regarding these operations.

3.3 FILL REQUIREMENTS

After subgrade preparation and observation have been completed, fill placement may begin. The first layer of fill material should be placed in a relatively uniform horizontal lift on the prepared subgrade. Fill materials should be free of organic or other deleterious materials, have a maximum particle size of 3 inches, be relatively well graded, and have a liquid limit less than 45 and a plasticity index less than 25. Most of the on site soils are suitable for use as structural fill with the exception of the existing topsoil; however, the moisture content of the otherwise suitable soils will most likely have to be adjusted to coincide with the moisture range required for structural fill. If a fine-grained silt or clay soil is used for fill, close moisture content control will be required to achieve the recommended degree of compaction.

Structural fill should be compacted to at least 95 percent of standard Proctor (ASTM D

698) maximum dry density. If granular fill soils are used and are of a free draining type (i.e., less than about 12 percent fines) for which impact compaction will not produce a well defined moisture-density relationship curve, they should be compacted to at least 70 percent relative density (ASTM Designations D 4253 and D 4254).

Fill should be placed in maximum lifts of 8 inches of loose material and should be compacted within the range of 3 percentage points below to 2 percentage points above the optimum moisture content value. If the fill is too dry, water should be uniformly applied across the affected fill area. If the fill is too wet, it must be dried. In either event, the fill should be thoroughly mixed by disking to obtain a relatively uniform moisture content throughout the lift immediately prior to compaction.

Each lift of fill should be tested by a representative of the geotechnical engineer prior to placement of subsequent lifts. The properly compacted fill should extend horizontally outward beyond the exterior perimeter of the building and foundations a distance equal to the height of fill or 5 feet, whichever is greater, prior to significant sloping. However, as noted in Section DRAINAGE AND GROUNDWATER CONSIDERATIONS of this report, the grades should be sloped away (gentle slopes) from the facility area to allow proper drainage. Permanent slopes should be constructed with a maximum slope of 3H:1V to provide long term stable slopes and also provide for easy maintenance of the vegetated slope face.

3.4 FOUNDATION RECOMMENDATIONS

Once the site has been properly prepared as discussed earlier, the planned construction can be supported on a mat type foundation bearing on a minimum of two feet of conditioned and re-compacted natural soils (excluding “fat” clay) or on properly compacted granular fill. The mat type footings can be designed for an allowable net soil bearing pressures of 750 psf, based on dead load plus design live load. However, the bearing pressures may be increased by one-third for transient loading conditions involving wind or earthquake forces. It is highly desirable to design the mat foundation such that the resultant remains within the middle third.

Foundations in unheated areas should be located at a depth of at least 18 inches below the final exterior grade to provide adequate frost protection. If the facility is constructed during the winter months or if the foundation soils will likely be subjected to freezing temperatures after foundation construction, then the foundation soils should be adequately protected from freezing.

The foundation excavations should be observed by a representative of PSI prior to steel or concrete placement to assess that the foundation materials are capable of supporting the design loads and are consistent with the bearing materials recommended in this report.

After opening, foundation excavations should be observed and concrete placed as quickly as possible to avoid exposure of the excavation bottoms to wetting and drying. Surface run-off water should be drained away from the excavations and not be allowed to pond. If possible, the foundation concrete should be placed during the same day the excavation is made. If it is required that the foundation excavations be left open for more than one day, they should be protected to reduce evaporation or entry of moisture.

Because sandy soils are often disturbed during foundation excavation operations, any sandy soils at the base of the footing excavations should be re-densified after excavation operations are completed. Field density tests should be conducted to verify compaction of the sandy soils in accordance with the fill requirements of Section 3.3 of this report prior to steel or concrete placement.

Based on the existing soil conditions and the site preparation specified herein, the design of mat foundations can be based on a subgrade modulus (k) of 50 pci. The subgrade modulus value represents an anticipated value that would be obtained in a standard in-situ plate test with a 1-foot square plate. Use of the subgrades modulus for design of on-grade structural elements should include appropriate modification based on dimensions as necessary.

The value should be adjusted for larger areas using the following expression for cohesive and cohesionless soil:

Modulus of Subgrade Reaction, ks = ( ) for cohesive soil and ks = k ( )2 for cohesionless soil where: ks = coefficient of vertical subgrade reaction for loaded area, k = coefficient of vertical subgrade reaction for 1x1 square foot area, and

B = width of area loaded, in feet

3.5 EARTH PRESSURE

Passive earth pressure develops at the front of footings as the footings push laterally into adjacent soils. The passive force (Pp) that resist lateral movement depends on the unit weight of the soil (γ), the footing embedment depth (Df), the Rankine passive earth pressure coefficient (Kp), and the shear strength of the soil.

The equivalent fluid pressure for the long term passive pressure case is estimated as Kp γ or 2.77 * (100 pcf) = 277 psf per foot of footing width. For long term resistance to sliding resistance, we recommend an ultimate friction coefficient of 0.5. These are ultimate values, and an appropriate factor of safety should be applied. PSI recommends a factor of safety of at least two.

For the case of short term transient loading, such as wind or seismic loading, the ultimate lateral resistance can be estimated as 2 times the undrained shear strength. This pressure diagram is rectangular in shape as shown below. For this case, the undrained shear strength is estimated to be 200 psf. Thus the pressure against the footing is 2 * (500 psf) = 1000 psf. The ultimate adhesion between the base of the footing and the soil can be estimated to be 500 psf for the short term case. Again, these are ultimate values and appropriate factors of safety should be applied. PSI recommends a factor of safety of at least two.

If the area over the footing is paved, the depth to the footing base can be taken as the depth of embedment of the footing. If the area above the footing is not paved, the upper eighteen inches should be ignored in the calculations as this depth is within the frost zone.

3.6 SITE CLASS

Quantitative determination of the site class in accordance with IBC 2012 requires specific actions, testing, analyses and subsurface investigation including a 100-foot deep boring.

However, Section 1613.3.2 Site Class Definitions of IBC 2012 states that Site Class D shall be used when site specific soil properties are not known with sufficient detail to define the site class unless the available geotechnical data or the building official determines that Site Class E or F soil is likely to be present at the site. Although a 100-foot deep boring was not drilled, the available subsurface data suggests that Site Class D is appropriate for this site and we recommend that it be used.

Data obtained from the Google data server, the USGS Earthquake Hazards Program information, and the requirements of IBC 2012, the project site coefficients Fa and Fv have been determined to be 1.000 and 1.500, respectively. The design spectral response accelerations, SDS and SD1, were determined to be 1.561g and 0.861g, respectively.

According to IBC 2012, sites supporting structures in site class “D” and below must be evaluated for slope instabilities, liquefaction and surface rupture due to faulting or lateral spreading. A detailed study of these effects was beyond PSI’s scope of services.

However, the following table presents a qualitative assessment of these issues considering the site class, the subsurface soil properties, the groundwater elevation, and probabilistic ground motions:

HAZARD RELATIVE

RISK

COMMENTS

Liquefaction Low The soil within the upper 10 feet of the subsurface profile is a cohesive soil underlain by dense sands

Slope Stability Low The site is relatively flat and does not/will not incorporate significant cut or fill slopes

Surface Rupture Low The site is not underlain by a mapped Holocene-aged fault

4.0 CONSTRUCTION CONSIDERATIONS

PSI should be retained to provide observation and testing of construction activities involved in the foundations, floor slabs, earthwork and related activities of this project. PSI can not accept any responsibility for any conditions that deviate from those described in this report, nor for the performance of the foundations or floor slabs if not engaged to also provide construction observation and testing for this project.

4.1 MOISTURE SENSITIVE SOILS/WEATHER RELATED CONCERNS

Some of the upper fine-grained soils encountered at this site were wet and are expected to be somewhat sensitive to disturbances caused by construction traffic and to changes in moisture content. The remaining upper fine-grained soils that were moist to relatively dry at the time of drilling are expected to be relatively sensitive to changes in moisture content;

if these fine-grained soils become wet, they are also expected to be sensitive to disturbances caused by construction traffic.

During wet weather periods increases in the moisture content of the soil can cause significant reduction in the soil strength and support capabilities. In addition, soils that become wet may be slow to dry and thus significantly retard the progress of grading and compaction activities. It will, therefore, be advantageous to perform earthwork and foundation construction during dry weather.

Also, some of the existing in-situ soils that will be present near the top of exposed subgrades or will be cut and used for fill may have to be dried to a suitable moisture content. Dry weather with favorable drying conditions (sunshine, low relative humidity, and/or wind) are best suited for these operations. This is especially important for this site considering the wet soils encountered in some areas.

4.2 DRAINAGE AND GROUNDWATER CONSIDERATIONS

Water should not be allowed to collect in excavations (foundations, utilities, etc.) or on prepared subgrades for floor slabs during construction. Positive site drainage should be maintained throughout construction activities. Undercut or excavated areas should be sloped toward one corner to facilitate removal of any collected rainwater, groundwater, or surface runoff.

The site grading plan should be developed to provide rapid drainage away from the building area and to inhibit infiltration of surface water around the perimeter of the building and beneath the floor slab. The grades should be sloped away from the building area.

Careful consideration should be given to the potential impact of landscaped areas and/or sprinkler systems on adjacent foundations and floor slabs. Roof runoff should be piped to a storm sewer, discharged upon a paved surface, or conveyed at least 10 feet away from the building perimeter prior to discharge upon unpaved surfaces.

Providing proper drainage both during construction and throughout the service life of the facility is especially important at this site because of the moist to relatively dry fine-grained soils identified in the borings as well as the proposed heavy structural loads. Increases in the moisture content of the fine-grained soils will result in reduced support capacity.

Groundwater was measured at depths as shallow as 7 to 8 feet in 5 of the 10 borings. It is possible that seasonal variations will cause fluctuations or a water table to be present at higher levels. Considering these measured groundwater levels, it would be prudent to avoid lowering the existing site grade. It may be necessary for the contractor to deal with saturated soils and/or seepage during site preparation operations. These groundwater conditions should be considered relative to the building design. Some dewatering operations may be required to allow work to proceed (e.g., excavation of utility trenches, undercutting, etc.) and permanent dewatering systems may be needed to inhibit damage to structural elements.

Any water accumulation should be removed from shallow excavations by pumping. The Geotechnical Engineer should be consulted if excessive or uncontrolled amounts of seepage occur.

4.3 EXCAVATIONS

In Federal Register, Volume 54, No. 209 (October 1989), the United States Department of Labor, Occupational Safety and Health Administration (OSHA) amended its "Construction Standards for Excavations, 29 CFR Part 1926, Subpart P". This document and subsequent updates were issued to better insure the safety of workmen entering trenches or excavations. It is mandated by this federal regulation that excavations (e.g., utility trenches, undercut areas, basement excavations, footing excavations, etc.) be constructed in accordance with the applicable OSHA guidelines. It is our understanding that these regulations are being strictly enforced and if they are not closely followed, the owner and the contractor could be liable for substantial penalties.

The contractor is solely responsible for designing and constructing stable, temporary excavations and should shore, slope, or bench the sides of the excavations as required to maintain stability of both the excavation sides and bottom. The contractor's "responsible person," as defined in 29 CFR Part 1926, should evaluate the soil exposed in the excavations as part of the contractor's safety procedures. In no case should slope height, slope inclination, or excavation depth, including utility trench excavation depth, exceed those specified in current local, state, and federal safety regulations.

We are providing this information solely as a service to our client. PSI does not assume responsibility for construction site safety or the contractor's compliance with local, state, and federal safety or other regulations.

5.0 REPORT LIMITATIONS

The recommendations submitted in this report are based on the available subsurface information obtained by PSI and design details furnished by Fisher & Arnold, Inc. for the proposed project. If there are any revisions to the plans for this project, or if deviations from the subsurface conditions noted in this report are encountered during construction, PSI should be notified immediately to determine if changes in the foundation recommendations are required. If PSI is not retained to review these changes, PSI will not be responsible for the impact of those conditions on the project.

The geotechnical engineer warrants that the findings, recommendations, specifications, or professional advice contained herein have been made after being prepared in accordance with generally accepted professional engineering practice in the local area. No other warranties are implied or expressed.

After the plans and specifications are more complete, the geotechnical engineer should be retained and provided the opportunity to review the final design plans and specifications to check that our engineering recommendations have been properly incorporated into the design documents. At this time, it may be necessary to submit supplementary recommendations. This report has been prepared for the exclusive use of Fisher & Arnold, Inc. for the specific application to the proposed additions at the electrical substation in

APPENDIX I

Insert Google Earth Image

December 2013

PSI File No.

0502928

Vicinity Map

Sikeston Substation

Country Road 478

Job Site

Insert Site Plan

December 2013

PSI File No.

0502928

Boring Plan

Sikeston Substation

Country Road 478

Sikeston, Missouri

B-1

B-2

B-5

B-4

B-3

B-6

B-7 B-8

B-9

B-10

APPENDIX II

GENERAL NOTES

SAMPLE IDENTIFICATION

The Unified Soil Classification System (USCS), AASHTO 1988 and ASTM designations D2487 and D-2488 are used to identify the encountered materials unless otherwise noted. Coarse-grained soils are defined as having more than 50% of their dry weight retained on a #200 sieve (0.075mm); they are described as: boulders, cobbles, gravel or sand. Fine-grained soils have less than 50% of their dry weight retained on a #200 sieve;

they are defined as silts or clay depending on their Atterberg Limit attributes. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size.

Description Flat:

Elongated:

Flat & Elongated:

Description Angular:

Subangular:

Subrounded:

Rounded:

Criteria Particles with width/thickness ratio > 3 Particles with length/width ratio > 3 Particles meet criteria for both flat and elongated

Descriptive Term Trace:

With:

Modifier:

Size Range Over 300 mm (>12 in.)

75 mm to 300 mm (3 in. to 12 in.)

19 mm to 75 mm (¾ in. to 3 in.)

4.75 mm to 19 mm (No.4 to ¾ in.)

2 mm to 4.75 mm (No.10 to No.4)

0.42 mm to 2 mm (No.40 to No.10)

0.075 mm to 0.42 mm (No. 200 to No.40)

0.005 mm to 0.075 mm <0.005 mm

Component Boulders:

Cobbles:

Coarse-Grained Gravel:

Fine-Grained Gravel:

Coarse-Grained Sand:

Medium-Grained Sand:

Fine-Grained Sand:

Silt:

Clay:

ANGULARITY OF COARSE-GRAINED PARTICLESRELATIVE DENSITY OF COARSE-GRAINED SOILS

N - Blows/foot

0 - 4 4 - 10 10 - 30 30 - 50 50 - 80

80+

Relative Density

Very Loose Loose

Medium Dense Dense

Very Dense Extremely Dense

RELATIVE PROPORTIONS OF FINES

% Dry Weight < 5%

5% to 12% >12%

Standard "N" penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2-inch O.D.

Split-Spoon.

A "N" penetration value corrected to an equivalent 60% hammer energy transfer efficiency (ETR) Unconfined compressive strength, TSF Pocket penetrometer value, unconfined compressive strength, TSF Moisture/water content, % Liquid Limit, % Plastic Limit, % Plasticity Index = (LL-PL),% Dry unit weight, pcf Apparent groundwater level at time noted

Criteria Particles have sharp edges and relatively plane sides with unpolished surfaces Particles are similar to angular description, but have rounded edges Particles have nearly plane sides, but have well-rounded corners and edges Particles have smoothly curved sides and no edges

N:

N60:

Qu:

Qp:

w%:

LL:

PL:

PI:

DD:

GRAIN-SIZE TERMINOLOGY PARTICLE SHAPE

SOIL PROPERTY SYMBOLS

Shelby Tube - 3" O.D., except where noted.

Rock Core Texas Cone Bulk Sample Pressuremeter Cone Penetrometer Testing with Pore-Pressure Readings

DRILLING AND SAMPLING SYMBOLS

Solid Flight Auger - typically 4" diameter flights, except where noted.

Hollow Stem Auger - typically 3¼" or 4¼ I.D.

openings, except where noted.

Mud Rotary - Uses a rotary head with Bentonite or Polymer Slurry Diamond Bit Core Sampler Hand Auger Power Auger - Handheld motorized auger

Split-Spoon - 1 3/8" I.D., 2" O.D., except where noted.

SFA:

HSA:

M.R.:

R.C.:

H.A.:

P.A.:

SS:

ST:

RC:

TC:

BS:

PM:

CPT-U:

GENERAL NOTES

QU - TSF N - Blows/foot Consistency

0 - 2 2 - 4 4 - 8

8 - 15 15 - 30 30 - 50

50+

Criteria Absence of moisture, dusty, dry to the touch Damp but no visible water Visible free water, usually soil is below water table

RELATIVE PROPORTIONS OF SAND AND GRAVEL

% Dry Weight < 15% 15% to 30% >30%

Descriptive Term Trace:

With:

Modifier:

0 - 0.25

0.25 - 0.50

0.50 - 1.00

1.00 - 2.00

2.00 - 4.00

4.00 - 8.00

8.00+

MOISTURE CONDITION DESCRIPTIONCONSISTENCY OF FINE-GRAINED SOILS

Description Blocky:

Lensed:

Layer:

Seam:

Parting:

Description Stratified:

Laminated:

Fissured:

Slickensided:

STRUCTURE DESCRIPTION

QU - TSF

Extremely Soft Very Soft

Soft Medium Hard

Moderately Hard Hard

Very Hard

SCALE OF RELATIVE ROCK HARDNESS ROCK BEDDING THICKNESSES

Consistency

Criteria Alternating layers of varying material or color with layers at least ¼-inch (6 mm) thick Alternating layers of varying material or color with layers less than ¼-inch (6 mm) thick Breaks along definite planes of fracture with little resistance to fracturing Fracture planes appear polished or glossy, sometimes striated

Criteria Greater than 3-foot (>1.0 m) 1-foot to 3-foot (0.3 m to 1.0 m) 4-inch to 1-foot (0.1 m to 0.3 m) 1¼-inch to 4-inch (30 mm to 100 mm) ½-inch to 1¼-inch (10 mm to 30 mm) 1/8-inch to ½-inch (3 mm to 10 mm) 1/8-inch or less "paper thin" (<3 mm)

Description Dry:

Moist:

Wet:

Description Very Thick Bedded

Thick Bedded Medium Bedded

Thin Bedded Very Thin Bedded Thickly Laminated Thinly Laminated

2.5 - 10 10 - 50

50 - 250 250 - 525

525 - 1,050 1,050 - 2,600

>2,600

(Continued)

Component Very Coarse Grained

Coarse Grained Medium Grained

Fine Grained Very Fine Grained

GRAIN-SIZED TERMINOLOGY

(Typically Sedimentary Rock)

ROCK VOIDS

Voids Pit

Vug Cavity Cave

Void Diameter <6 mm (<0.25 in) 6 mm to 50 mm (0.25 in to 2 in) 50 mm to 600 mm (2 in to 24 in) >600 mm (>24 in)

ROCK QUALITY DESCRIPTION

RQD Value 90 -100 75 - 90 50 - 75 25 -50

Less than 25

Size Range >4.76 mm

2.0 mm - 4.76 mm

0.42 mm - 2.0 mm

0.075 mm - 0.42 mm <0.075 mm

Rock generally fresh, joints stained and discoloration extends into rock up to 25 mm (1 in), open joints may contain clay, core rings under hammer impact.

Rock mass is decomposed 50% or less, significant portions of the rock show discoloration and weathering effects, cores cannot be broken by hand or scraped by knife.

Rock mass is more than 50% decomposed, complete discoloration of rock fabric, core may be extremely broken and gives clunk sound when struck by hammer, may be shaved with a knife.

Rock Mass Description Excellent

Good Fair Poor

Very Poor

DEGREE OF WEATHERING

Slightly Weathered:

Weathered:

Highly Weathered:

Criteria Cohesive soil that can be broken down into small angular lumps which resist further breakdown Inclusion of small pockets of different soils Inclusion greater than 3 inches thick (75 mm) Inclusion 1/8-inch to 3 inches (3 to 75 mm) thick extending through the sample Inclusion less than 1/8-inch (3 mm) thick

Very Soft Soft

Firm (Medium Stiff) Stiff

Very Stiff Hard

Very Hard

OH

CH

MH

OL

CL

ML

SC

SM

SP

COARSE

GRAINED

SOILS

SW

TYPICAL

DESCRIPTIONS

WELL-GRADED GRAVELS, GRAVEL -

SAND MIXTURES, LITTLE OR NO FINES

POORLY-GRADED GRAVELS, GRAVEL

- SAND MIXTURES, LITTLE OR NO

FINES

SILTY GRAVELS, GRAVEL - SAND -

SILT MIXTURES

LETTERGRAPH

SYMBOLS

MAJOR DIVISIONS

SOIL CLASSIFICATION CHART

PT

GC

GM

GP

GW

CLAYEY GRAVELS, GRAVEL - SAND -

CLAY MIXTURES

WELL-GRADED SANDS, GRAVELLY

SANDS, LITTLE OR NO FINES

POORLY-GRADED SANDS, GRAVELLY

SAND, LITTLE OR NO FINES

SILTY SANDS, SAND - SILT MIXTURES

CLAYEY SANDS, SAND - CLAY

MIXTURES

INORGANIC SILTS AND VERY FINE

SANDS, ROCK FLOUR, SILTY OR

CLAYEY FINE SANDS OR CLAYEY

SILTS WITH SLIGHT PLASTICITY

INORGANIC CLAYS OF LOW TO

MEDIUM PLASTICITY, GRAVELLY

CLAYS, SANDY CLAYS, SILTY CLAYS,

LEAN CLAYS

ORGANIC SILTS AND ORGANIC SILTY

CLAYS OF LOW PLASTICITY

INORGANIC SILTS, MICACEOUS OR

DIATOMACEOUS FINE SAND OR SILTY

SOILS

INORGANIC CLAYS OF HIGH

PLASTICITY

ORGANIC CLAYS OF MEDIUM TO HIGH

PLASTICITY, ORGANIC SILTS

PEAT, HUMUS, SWAMP SOILS WITH

HIGH ORGANIC CONTENTS

CLEAN

GRAVELS

GRAVELS WITH

FINES

CLEAN SANDS

(LITTLE OR NO FINES)

SANDS WITH

FINES

LIQUID LIMIT

LESS THAN 50

LIQUID LIMIT

GREATER THAN 50

HIGHLY ORGANIC SOILS

GRAVEL

AND

GRAVELLY

SOILS

(APPRECIABLE AMOUNT

OF FINES)

(APPRECIABLE AMOUNT

OF FINES)

(LITTLE OR NO FINES)

FINE

GRAINED

SOILS

SAND

AND

SANDY

SOILS

SILTS

AND

CLAYS

SILTS

AND

CLAYS

MORE THAN 50%

OF MATERIAL IS

LARGER THAN NO.

200 SIEVE SIZE

MORE THAN 50%

OF MATERIAL IS

SMALLER THAN

NO. 200 SIEVE

SIZE

MORE THAN 50%

OF COARSE

FRACTION

PASSING ON NO. 4

SIEVE

MORE THAN 50%

OF COARSE

FRACTION

RETAINED ON NO.

4 SIEVE

NOTE: DUAL SYMBOLS ARE USED TO INDICATE BORDERLINE SOIL CLASSIFICATIONS

APPENDIX III

CL

CH

SC

6-6-5 N=11

4-3-4 N=7

3-1-3 N=4

4-6-7 N=13

4-6-7 N=13

Brown Clayey Sand with Gravel (FILL)

Firm, Gray Sandy Clay trace Gravel (CL)

Soft, Gray Sandy Clay (CH)

Medium Dense, Gray Clayey Sand (SC)

Medium Dense, Gray Clayey Sand (SC)

Boring Terminal Depth: 11½ feet

PL

El ev at io n (fe et

LL

4.0

R ec ov er y (in ch es

Station: N/A Offset: N/A

The stratification lines represent approximate boundaries. The transition may be gradual.

D ep th fe et

Sample Types:

STRENGTH, tsf

None

None

N/A

0502928 Sikeston Substation

CR-478

Sikeston, Missouri

Additional Remarks

U S

C S

C la ss ifi ca tio n

Boring Location:

Qp

Sheet 1 of 1

Professional Service Industries, Inc.

4161 Ridgemoor Avenue Memphis, TN 38118 Telephone: (901) 365-1802 Fax: (901) 366-7233

Sa m pl e

Ty pe

2.0

While Drilling

Upon Completion

Delay

Drilling Method:

Sampling Method:

Hammer Type:

WATER LEVELS

M oi st ur e, MoistureMATERIAL DESCRIPTION

STANDARD PENETRATION

TEST DATA

N in blows/ft

PSI Job No.:

Project:

Location:

Latitude: 36.875829° Longitude: -89.624817° Drill Rig: CME 55 Remarks:

Shelby Tube Hand Auger Calif. Sampler Texas Cone

S P

T B lo w s pe r 6 -in ch (S

S

Qu

Auger Cutting Split-Spoon Rock Core

S am pl e

N o.

G ra ph ic

L og

LOG OF BORING B- 1

Completion Depth:

Date Boring Started:

Date Boring Completed:

Logged By:

Drilling Contractor:

11.5 ft 11/18/13 11/18/13 J. Jester

PSI

Hollow Stem Auger

SS

Automatic

CH

SC

SP

2-2-3 N=5

3-3-5 N=8

2-3-2 N=5

5-8-13 N=21

4-7-10 N=17

Gray Sandy Clay with Gravel (FILL)

Firm, Gray Sandy Clay (CH)

Firm, Gray Sandy Clay (CH)

Medium Dense, Gray Clayey Sand with Gravel (SC)

Medium Dense, Gray Sand (SP)

Boring Terminal Depth: 11½ feet

PL

El ev at io n (fe et

LL

4.0

R ec ov er y (in ch es

Station: N/A Offset: N/A

The stratification lines represent approximate boundaries. The transition may be gradual.

D ep th fe et

Sample Types:

STRENGTH, tsf

None

None

N/A

0502928 Sikeston Substation

CR-478

Sikeston, Missouri

Additional Remarks

U S

C S

C la ss ifi ca tio n

Boring Location:

Qp

Sheet 1 of 1

Professional Service Industries, Inc.

4161 Ridgemoor Avenue Memphis, TN 38118 Telephone: (901) 365-1802 Fax: (901) 366-7233

Sa m pl e

Ty pe

2.0

While Drilling

Upon Completion

Delay

Drilling Method:

Sampling Method:

Hammer Type:

WATER LEVELS

M oi st ur e, MoistureMATERIAL DESCRIPTION

STANDARD PENETRATION

TEST DATA

N in blows/ft

PSI Job No.:

Project:

Location:

Latitude: 36.875948° Longitude: -89.624149° Drill Rig: CME 55 Remarks:

Shelby Tube Hand Auger Calif. Sampler Texas Cone

S P

T B lo w s pe r 6 -in ch (S

S

Qu

Auger Cutting Split-Spoon Rock Core

S am pl e

N o.

G ra ph ic

L og

LOG OF BORING B- 2

Completion Depth:

Date Boring Started:

Date Boring Completed:

Logged By:

Drilling Contractor:

11.5 ft 11/18/13 11/18/13 J. Jester

PSI

Hollow Stem Auger

SC

2-4-4 N=8

2-1-3 N=4

5-5-6 N=11

1-3-5 N=8

4-9-12 N=21

Gray Sandy Clay trace Gravel (FILL)

Gray Sandy Clay trace Gravel (FILL)

Medium Dense, Brown Clayey Sand (SC)

Loose, Gray Clayey Sand (SC)

Medium Dense, Gray Sand (SP)

Boring Terminal Depth: 11½ feet

PL

El ev at io n (fe et

LL

4.0

R ec ov er y (in ch es

Station: N/A Offset: N/A

The stratification lines represent approximate boundaries. The transition may be gradual.

D ep th fe et

Sample Types:

STRENGTH, tsf

None

None

N/A

0502928 Sikeston Substation

CR-478

Sikeston, Missouri

Additional Remarks

U S

C S

C la ss ifi ca tio n

Boring Location:

Qp

Sheet 1 of 1

Professional Service Industries, Inc.

4161 Ridgemoor Avenue Memphis, TN 38118 Telephone: (901) 365-1802 Fax: (901) 366-7233

Sa m pl e

Ty pe

2.0

While Drilling

Upon Completion

Delay

Drilling Method:

Sampling Method:

Hammer Type:

WATER LEVELS

M oi st ur e, MoistureMATERIAL DESCRIPTION

STANDARD PENETRATION

TEST DATA

N in blows/ft

PSI Job No.:

Project:

Location:

Latitude: 36.876512° Longitude: -89.624155° Drill Rig: CME 55 Remarks:

Shelby Tube Hand Auger Calif. Sampler Texas Cone

S P

T B lo w s pe r 6 -in ch (S

S

Qu

Auger Cutting Split-Spoon Rock Core

S am pl e

N o.

G ra ph ic

L og

LOG OF BORING B- 3

Completion Depth:

Date Boring Started:

Date Boring Completed:

Logged By:

Drilling Contractor:

11.5 ft 11/18/13 11/18/13 J. Jester

PSI

Hollow Stem Auger

CH

SC

SP

3-5-6 N=11

3-5-4 N=9

2-1-3 N=4

3-7-12 N=19

2-4-10 N=14

Stiff, Gray Sandy Clay (CH)

Stiff, Gray Sandy Clay (CH)

Soft, Gray Sandy Clay (CH)

Medium Dense, Gray Clayey Sand (SC)

Medium Dense, Gray Sand (SP)

Boring Terminal Depth: 11½ feet

PL

El ev at io n (fe et

LL

4.0

R ec ov er y (in ch es

Station: N/A Offset: N/A

The stratification lines represent approximate boundaries. The transition may be gradual.

D ep th fe et

Sample Types:

STRENGTH, tsf

None

None

N/A

0502928 Sikeston Substation

CR-478

Sikeston, Missouri

Additional Remarks

U S

C S

C la ss ifi ca tio n

Boring Location:

Qp

Sheet 1 of 1

Professional Service Industries, Inc.

4161 Ridgemoor Avenue Memphis, TN 38118 Telephone: (901) 365-1802 Fax: (901) 366-7233

Sa m pl e

Ty pe

2.0

While Drilling

Upon Completion

Delay

Drilling Method:

Sampling Method:

Hammer Type:

WATER LEVELS

M oi st ur e, MoistureMATERIAL DESCRIPTION

STANDARD PENETRATION

TEST DATA

N in blows/ft

PSI Job No.:

Project:

Location:

Latitude: 36.876645° Longitude: -89.624528° Drill Rig: CME 55 Remarks:

Shelby Tube Hand Auger Calif. Sampler Texas Cone

S P

T B lo w s pe r 6 -in ch (S

S

Qu

Auger Cutting Split-Spoon Rock Core

S am pl e

N o.

G ra ph ic

L og

LOG OF BORING B- 4

Completion Depth:

Date Boring Started:

Date Boring Completed:

Logged By:

Drilling Contractor:

11.5 ft 11/19/13 11/19/13 J. Jester

PSI

Hollow Stem Auger

SC

SP

2-4-3 N=7

5-7-10 N=17

3-5-12 N=17

3-6-12 N=18

3-8-11 N=19

Loose, Brown Clayey Sand (SC)

Medium Dense, Brown Clayey Sand (SC)

Medium Dense, Brown Clayey Sand (SC)

Medium Dense, Gray Sand (SP)

Medium Dense, Gray Sand (SP)

Boring Terminal Depth: 11½ feet

PL

El ev at io n (fe et

LL

4.0

R ec ov er y (in ch es

Station: N/A Offset: N/A

The stratification lines represent approximate boundaries. The transition may be gradual.

D ep th fe et

Sample Types:

STRENGTH, tsf

8 feet

None

N/A

0502928 Sikeston Substation

CR-478

Sikeston, Missouri

Additional Remarks

U S

C S

C la ss ifi ca tio n

Boring Location:

Qp

Sheet 1 of 1

Professional Service Industries, Inc.

4161 Ridgemoor Avenue Memphis, TN 38118 Telephone: (901) 365-1802 Fax: (901) 366-7233

Sa m pl e

Ty pe

2.0

While Drilling

Upon Completion

Delay

Drilling Method:

Sampling Method:

Hammer Type:

WATER LEVELS

M oi st ur e, MoistureMATERIAL DESCRIPTION

STANDARD PENETRATION

TEST DATA

N in blows/ft

PSI Job No.:

Project:

Location:

Latitude: 36.876994° Longitude: -89.625068° Drill Rig: CME 55 Remarks:

Shelby Tube Hand Auger Calif. Sampler Texas Cone

S P

T B lo w s pe r 6 -in ch (S

S

Qu

Auger Cutting Split-Spoon Rock Core

S am pl e

N o.

G ra ph ic

L og

LOG OF BORING B- 5

Completion Depth:

Date Boring Started:

Date Boring Completed:

Logged By:

Drilling Contractor:

11.5 ft 11/19/13 11/19/13 J. Jester

PSI

Hollow Stem Auger

CH

SC

SP

2-2-2 N=4

2-10-15 N=25

3-6-9 N=15

5-10-10 N=20

3-7-12 N=19

Brown Clayey Sand (FILL)

Very Stiff, Brown and Gray Sandy Clay (CH)

Medium Dense, Brown Clayey Sand (SC)

Medium Dense, Gray Clayey Sand (SC)

Medium Dense, Gray Sand (SP)

Boring Terminal Depth: 11½ feet

PL

El ev at io n (fe et

LL

4.0

R ec ov er y (in ch es

Station: N/A…