Geotechnical Report - 9-1-2016.pdf

September 1, 2016 VA SF CLC Hospice, Sioux Falls, SD 06054.034

EXECUTIVE SUMMARY

The Schemmer Associates Inc. has completed this geotechnical exploration for the proposed CLC Cottage-Hospice Project No. 438-420 at the VA Hospital Campus in Sioux Falls, South Dakota. The new residential building will be constructed upon a sloping, tree and lawn covered area of the campus. This project consists of a 9,000 square foot single story, non-basemented cottage building having a generally rectangular shape with overall dimensions of 114 by 81 feet.

A small parking will be constructed along the street to the southeast of the building. A patient drop off drive and car port entrance will be constructed at the southwest corner of the building.

This building will be connected to the nearby administration building by an exterior hallway.

Although preliminary information provided to this engineer suggested that the building site was only slightly sloping, we find that the site is moderately sloping. Soil fill is required to create the level pad on which the building will be constructed. Fill of about 2 to 10.5 feet above existing surface grade is required.

The building is a single-story structure, having a grade supported first floor with partial second story attic/mezzanine level. The building will be supported by steel frame construction on shallow footings, with light gauge metal studs. The following building design loads have been provided by the structural engineer: maximum column load of 90 kips with maximum wall load of 1.5 kips per lineal foot.

Site geology consist of Peoria Loess, loess deposited during the Wisconsin Age glacial period, over pre-Wisconsin Age colluvium, and over glacial till. Area bedrock consists of Sioux Quartzite.

The loess extends to a depth of about 14 to 16 feet. A layer of colluvium exists with a thickness of 6 to 10 feet below the loess. Glacial till exists below the colluvium to the top of the bedrock.

Some soil fill was already placed on this site. However, we do not know if it was properly placed for support of a future building. We recommend that existing fill be removed and replaced with structurally compacted fill which is monitored for compliance to the project specification. We recommend that a uniform pad of compacted fill be placed below the building area to support the new foundations.

The loess exists with low to medium strength in a very moist to wet condition. It is also compressible under the weight of the new fill to be placed above existing grade. After fill placement, we recommend the loess be compressed using the weight of a soil surcharge. The surcharge shall cover the entire building area, plus 10 feet beyond the outer edges of the building.

We recommend that the surcharge be kept on site for a minimum period of 3.5 months, or 105 days.

After our recommended site preparation, the subsoils are suitable for support of the proposed building on shallow footings. A limited net allowable bearing pressure is provided in this Report.

REPORT OF GEOTECHNICAL EXPLORATION

COMMUNITY LIVING CENTER, COTTAGE-HOSPICE

PROJECT No. 438-420

DEPARTMENT OF VETERAN AFFAIRS MEDICAL CENTER

SOUIX FALLS, SOUTH DAKOTA

SEPTEMBER 1, 2016

SCHEMMER PROJECT NO. 06054.034

Table of Contents Page No.

1.0 INTRODUCTION

1.1 Project Information

1.2 Scope of Service

1.3 Report Format

2.0 EXPLORATION RESULTS

2.1 Scope of Field Exploration

2.2 Laboratory Test Program

2.3 General Area Geology

2.4 Site Surface Conditions

2.5 Subsurface Conditions

2.6 Groundwater Data

2.7 Seismic Site Class

3.0 ENGINEERING RECOMMENDATIONS

3.1 Project Summary

3.2 Geotechnical Overview

3.3 Site Subgrade Preparation

3.4 Fill Requirements

3.5 Backfill

3.6 Fill-Related Settlement and Soil Heave

3.7 Foundation Recommendations

3.8 Foundation Drains

3.9 Surface Drainage

3.10 Exterior Pavement and Sidewalk Recommendations

3.11 Grade-Supported Floor Slabs

3.12 Additional Considerations

4.0 CONSTRUCTION CONSIDERATIONS

5.0 OBSERVATION AND TESTING

6.0 FIELD EXPLORATION PROCEDURES

6.1 Soil Sampling

6.2 Soil Classification

7.0 STANDARD OF CARE

APPENDIX

1 September 1, 2016

REPORT OF GEOTECHNICAL EXPLORATION

COMMUNITY LIVING CENTER, COTTAGE-HOSPICE

PROJECT No. 438-420

DEPARTMENT OF VETERAN AFFAIRS MEDICAL CENTER

SOUIX FALLS, SOUTH DAKOTA

SEPTEMBER 1, 2016

SCHEMMER PROJECT NO. 06054.034

1.0 INTRODUCTION

1.1 Project Information

This Report summarizes subsoil exploration work, laboratory findings, and geotechnical engineering conclusions and recommendations by The Schemmer Associates Inc. (Schemmer) for site preparation, subgrade preparation, pavement subgrade design parameters, and foundation design parameters for the Veteran Affairs (VA) Medical Center Community Living Center (CLC) Cottage-Hospice, and associated parking lot. This work was completed in accordance with our proposal of services for geotechnical project scope, provided during December of 2015.

1.2 Scope of Service

The scope of service for this subsoil exploration was limited to:

1. Advance two (2) borings to depths of 35 to 50 feet below existing surface grade;

2. Perform laboratory tests to aid in classifying the soils and estimating their engineering properties; and

3. Analyze results of laboratory testing to determine site and foundation-related recommendations, with regard to:

a. general discussion of existing site and soil conditions and their impact on the proposed construction;

b. characteristics of existing soils as they relate to proposed grading, site preparation, floor support, footing support, and pavement support;

c. minimum depth to suitable bearing material for foundations and allowable bearing pressures for shallow footing design;

d. seismic design parameter required by the building code;

e. recommendations for site improvements including evaluation of soil and other materials requiring excavation and replacement or densification;

f. recommendations for exterior sidewalk subgrade and for automobile drive, truck drive and parking area subgrades;

g. recommended types of fill and backfill soil materials and compaction requirements for support of pavements and structures;

h. active, passive, and at-rest lateral earth pressures for use in design of lateral earth-supported footings;

i. analysis of soil to ascertain presence of potentially expansive soils and recommendations, as necessary ;

j. estimated consolidation magnitudes, surcharge recommendations; and anticipated required waiting times due to fill placement, as necessary;

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k. frost-related design considerations;

l. comments on soil reactivity, and

m. anticipation of, management of, and recommendations for drainage of surface water and groundwater.

1.3 Report Format

The purposes of this Report are to describe our field observations; present field and laboratory test results; and provide geotechnical engineering recommendations based on the subsoil conditions encountered. Provided in the Appendix to this Report are a Boring Location Plan, Logs of Test Borings, a Summary of Soil Test Results, a page describing Classification of Soils for Engineering Purposes, and General Notes defining symbols and terms listed on the boring logs in this Report.

2.0 EXPLORATION RESULTS

2.1 Scope of Field Exploration

A total of two test borings, labeled B-1 and B-2, were advanced on July 21, 2016, for the purpose of gathering area subsurface data. Borings were placed at diagonally opposite corners of the proposed building area, one on the southwest and one on the northeast corners of the building areas, as shown on the attached Boring Location Plan. Borings were placed at locations allowed by existing surface and subsurface features and to provide coverage of the proposed construction area without unnecessary adverse impact to existing site features.

Safety considerations were also used in determining the boring locations. The locations were elected to not interfere with existing buried and overhead utilities. Locations of underground utilities were estimated using an existing utility plan sheet provided by our client.

2.2 Laboratory Test Program

Tests performed on the selected soil samples included a limited number of water content, dry unit weight, unconfined compressive strength, Atterberg limits, and visual classification. A complete table of laboratory test results is included in the Appendix to this Report. Each test was performed in conformance with the current ASTM or state-of-the-art test procedures.

Based on the results of the testing program, the field boring logs were reviewed and supplemented as presented in the Appendix. These final logs represent our interpretation of the in-place soil conditions at each boring location.

2.3 General Area Geology

General geology of this area consists of bedrock covered by glacial till and loess. The bedrock in this area generally consists of Sioux Quartzite, a hard rock made up of metamorphosed quartz sandstone. Several periods of glaciation have occurred in this area since the bedrock was last uncovered. Some of the glaciers covered this area and some did not extend to this area. The geologic periods when glaciers covered this area left deposits of glacial till clay and sandy outwash soils. Glacial ice did not cover this site during the most recent period of cold climate, but layers of eolian soils or loess were deposited. Eolian soils are soils deposited by wind as dust.

The dust is blown out of the sand bars in streams that flow from melting glaciers. In the upper Midwestern part of the United States, loess is usually deposed during a geologic period when

3 September 1, 2016 glacial ice existed near this location, such as from glaciers that extended into North Dakota and Minnesota. Loess, glacial till, and man-made fill are the soils found near the ground surface at this project location. The fill appears to have been obtained from an undisclosed glacial till borrow source.

2.4 Site Surface Conditions

The new CLC Cottage-Hospice will be constructed near the north-central edge of this VA campus, overlooking 22nd Street, on a portion of the campus that this currently covered by mature trees and mowed lawn. At-grade structures associated with existing buried utility lines exist near this area. We are aware that a buried electrical line and a sanitary sewer exist across the proposed building area. Lawn sprinkler lines exist within this area, but they were not located for this investigation. All other utilities are located outside the proposed building area.

The pavement of a private street within the facility exists immediately south of the building area.

The Administration Building for the facility exists southwest of the construction area.

The VA hospital facility exists within a residential portion of the City of Sioux Falls. Some small business, multi-family housing, and a city park exist within the surrounding area.

2.5 Subsurface Conditions

We are aware that a buried electrical line and sanitary sewer pipe exist below the proposed building area. These lines will be relocated prior to building construction. We understand that irrigation lines will be cut as they are encountered, and will be repaired after construction.

The subsurface conditions encountered in the borings have been used to infer the general soil conditions at the site. We assume the soil conditions between borings are fairly represented by the borings. During construction, if conditions are encountered other than that described below and as shown on the Boring Logs included in the Appendix to this Report, it is important that we be informed to evaluate the exposed conditions with respect to their effect on our recommendations. A layer of topsoil exists over the grass-covered surfaces away from existing pavements. The topsoil layer appears to be no more than 8 inches thick.

The following is a brief review of the various layers of soil encountered. All depths given are relative to the ground surface at the time of drilling. Please refer to the boring logs in the Appendix for a more complete description of soil conditions at each boring location. Separate descriptions are provided for each soil geologic description shown on the boring logs.

Fill – Soil placed by human activities was found below the topsoil to a depth of about 2 to

5.5 feet at borings B-1 and B-2, respectively. Properties of the fill at the boring locations varies from apparently well compacted to apparently poorly compacted. This soil consists of sandy lean clay and of lean clay with little sand, both apparently from an unknown glacial till source. Samples of this soil were tested and found to exist with the following measured in-place properties:

Water content – 19 to 23% Dry unit weight – 88 to 100 pcf Unconfined compressive strength – 1.034 to 3.216 tsf Liquid limit – 39% Plastic limit – 22%

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Plasticity index – 17 Classification (Unified) – Sandy Lean Clay (CL) and Lean Clay (CL)

Colluvium, Peoria Formation – Soils eroded from loess on the hill up-gradient from this location and redeposited to a lower elevation of the slope were found below the fill to depths of about 5 to 8 feet at the boring B-1 and B-2 locations, respectively. The upper few feet of this soil is weathered and exists with medium to high plasticity. The unweathered colluvium exists with medium plasticity. This soil consists of lean clay in a moist to very moist and medium stiff to stiff consistency with the following measured in-place properties:

Water content – 22 to 34% Dry unit weight – 78 to 97 pcf Unconfined compressive strength – 0.80 tsf Passing No. 200 sieve - >95% Classification (Unified) – Lean Clay (CL)

Wisconsin Loess, Peoria Loess – Eolian soil placed as dust by wind during the time of the Wisconsin age glaciers is found below the Peoria Formation soils. This loess extends to depths of about 14 to 16 feet below grade at the locations of borings B-1 and B-2, respectively. The upper few feet of loess consists of lean clay with medium to high plasticity in a moist to very moist and stiff condition. The rest of the loess consists of low to medium plasticity lean clay in a moist to very moist and medium stiff to stiff condition.

This soil exists with the following measured in-place properties:

Water content – 22 to 29% Dry unit weight – 97 to 100 pcf Unconfined compressive strength – 0.64 to 1.88 tsf Passing No. 200 sieve - >95% Classification (Unified) – Lean Clay (CL)

Colluvium, Illinoisan Formation – Soils placed by erosion of parent soil derived from glacial till were found below the loess at both borings. At boring B-1 this colluvium is found between depths of about 17 and 27 feet. At boring B-2, this soil is found between depths of about 16 and 22 feet. The presence of medium to coarse sand grains within this soil shows that it was eroded from glacial till, since there is no medium to coarse sand found in loess deposits. This soil consists of low plasticity silt with varying amounts of sand that was eroded at some time around the period of the Illinoisan glaciers or after that time. The groundwater level is perched within this soil, above the glacial till. The soil exists in a wet and loose to medium dense condition with the following measured in-place properties:

Water content – 29% Dry unit weight – 97 to 100 pcf Unconfined compressive strength – 0.62 tsf Classification (Unified) – Silt (ML)

Illinoisan Glacial Till – Soils placed by glaciers and apparently not subjected to significant surface weathering affects are found below the Illinoisan Formation at both boring locations. The color and properties of this soil suggest to us that it was placed during the Illinoisan glacial period. We understand that Kansan glacial till soils exist below the Illinoisan till and extend to the bedrock in this area. The depth from the surface to the top

5 September 1, 2016 of the glacial till varies, but is about 25 feet below the surface at our borings. The upper 5 to 10 feet of till exists in a stiff condition, with very stiff clay till below. Sand and gravel seams were found to exist within this material, with some water collected within the sand seams. Most of the till consists of medium plasticity, sandy lean clay in a moist condition.

Samples of this soil were tested and found to exist with the following measured in-place properties:

Water content – 13 to 19% Dry unit weight – 106 to 111 pcf Unconfined compressive strength – 0.38 to 3.21 tsf Classification (Unified) – Sandy Lean Clay (CL)

2.6 Groundwater Data

Groundwater levels should be expected to fluctuate seasonally and yearly from the groundwater readings noted on the boring logs. The evaluator should know the time of year that the borings were drilled and the history of precipitation prior to drilling when extrapolating water levels at other points in time using the groundwater readings from the boring logs.

Groundwater was encountered during drilling at depths of 20 and 18.5 feet within borings B-1 and B-2, respectively, on July 21, 2016. This water is perched above the glacial till clay within the silt colluvium. The groundwater level is found to vary widely in this area, dependent upon rainfall intensity, rainfall duration, and season of the year. A monitor well would need to be installed to obtain long-term groundwater data at this location.

2.7 Seismic Site Class

The Department of Veterans Affairs requires foundation seismic analyses in accordance with the 2012 International Building Code (IBC). The 2012 IBC requires a boring be advanced to a depth of 100 feet or to bedrock, if bedrock is encountered at a depth less than 100 feet. The Seismic Site Class is determined by the soil properties above the bedrock, to a maximum depth of 100 feet below surface grade.

Schemmer has data from two borings that have been advanced at the VA Medical Center, Sioux Falls, South Dakota campus. Our project scope allowed for a maximum of 75 lineal feet of soil boring from two boring locations. Area information from the South Dakota Geological Survey shows bedrock to consist of Sioux Quartzite below about 100 feet of overburden soils in the area of this project. Previous data from this campus has found 90 feet of soil overburden to exist upon the bedrock.

Medium stiff to stiff clay of loessial and colluvial deposition exists above the glacial till with combined thickness of about 25 feet. Very stiff glacial till then extends below these soils with a thickness of 65 to 75 feet. No layers of soft to medium stiff soil (undrained shear strength less than 500 psf), no soil with a plasticity index greater than 20, and no soil with a water content of 40 percent or greater with a profile 10 feet or more thick exists at these boring locations.

We reviewed the soil conditions in relationship to the criteria set forth in Section 1613.3.2 of the 2012 IBC in conjunction with Chapter 20 of the reference “Minimum Design Loads for Buildings and Other Structures (7-10)”, 2010, published by ASCE. These criteria find that a Seismic Site Class of D shall be used for this site. We recommend the project structural engineer shall use

6 September 1, 2016 this Site Class value in seismic evaluation of the proposed structures. Other criteria for structural design are provided in the IBC, based on the Site Class.

3.0 ENGINEERING RECOMMENDATIONS

3.1 Project Summary

The engineering recommendations made in this Report are based on our understanding of the project as discussed in the following paragraphs. The recommendations are valid for a specific set of project conditions. If the characteristics of the project should change from those indicated in this section, it is important that we be informed so that we can determine whether the new conditions affect our recommendations.

A single-story building with a partial attic/mezzanine second level, and having a slab-on-grade lower level floor is proposed. Steel framing will be supported by shallow column and wall footings.

Light gauge metal studs will also provide structure support. Shallow footings are proposed. The building has outer dimensions of about 114 by 81 feet. A main entrance with car port cover is proposed at the southwest corner of the building. Other exits from the main level are located at strategic locations around the building perimeter. A drop-off driveway will be constructed to the main entrance from the existing private street location south of this building area. An exterior hallway will extend from the west side of this building to the basement level of the nearby Administration Building. The main level will have a finished floor level of Elevation 1501.11 feet.

A new parking lot with six stalls will be constructed southeast of the building area. Sidewalks will connect this building to area streets and existing sidewalks.

Foundation support loads were provided by the project structural engineer with Schemmer. The columns will have a maximum load of 90 kips. The walls will have a maximum axial load of 1.5 kips per lineal foot. A floor load of up to 100 psf is estimated.

A significant amount of fill will be placed above existing grade to provide the finished slab-on-grade level of Elevation 1501.11 feet. From 1.8 to 10.3 feet of fill above existing grade will be place. Around the building, changes to grade will consist mainly of fill with a resulting fill slope having inclination of 4:1 on the north, part of the west, and the east sides of the building. Rather flat slopes will exist along the entire south side and much of the west side of the building. A sidewalk will be placed around the perimeter of the building with connections to area facility sidewalks and the small parking lot.

3.2 Geotechnical Overview

This section provides a short, general discussion of what we consider the geotechnical aspects of the site. Each of these items is discussed in greater detail within other sections of this Report.

The existing soil fill at this site is found to be variable. We recommend that all of the existing fill soil be excavated to expose the natural soils below. After existing fill is removed, natural soils shall be overexcavated to a level of 6.5 feet below the finished floor level.

The recommended soil overexcavation is expected to impact underground electrical and communication lines near the northwest corner of the building. These lines shall be protected or relocated.

7 September 1, 2016

Remove the existing sanitary sewer pipe from below the building area and relocate it around the building area. Care shall be used in the relocation design so that any new fill placed above existing grade that is placed over the pipe does not cause the formation of a sag in the pipe due to subsoil consolidation.

The thick new fill will compress the loessial and colluvial subsoils. Settlement due to consolidation of up to 5 inches is estimated under the weight of 10.3 feet of fill above existing grade. The subsoils will need to be compressed before building construction is begun. We recommend the use of a surcharge left in place for a period of time to compress the loessial and colluvial soils.

The new footings shall be placed to a suitable depth below the normal depth of frost penetration in this area. Our site preparation recommendations will provide for a layer of compacted clay fill at least 12 inches thick below the base of the exterior footings. Greater thickness of fill will remain below interior footings. This minimal thickness of fill below the footings will not significantly increase the bearing capacity for footings supported near the natural colluvium and loess below this site. We have determined a limited net allowable bearing pressure in design of 2,500 psf for this structure, based on the loess soils found below grade at the southwest corner of the building area in boring B-1.

A new parking lot will be constructed over existing grade to the southeast of the proposed building.

Up to 3 feet of fill above existing grade will be placed. We understand that the existing underground utility wires below this portion of the site will not be removed. We recommend that existing grade next to the street be overexcavated to a depth of 1 foot below base of pavement grade and replaced with new fill soil.

The car port at the main entrance will be supported on shallow footings. A covered hallway will extend to the existing Administration building to the west. Site soils are suitable to support these footings without any additional preparation below footings. Overexcavate the existing soil to a depth of 2 feet below top of floor subgrade level to provide uniform slab support.

3.3 Site Subgrade Preparation

Heavily root-infested topsoil shall be excavated from the ground surface and stockpiled for later covering of the finished grades over landscape areas. We estimate that 8 inches of topsoil covers the site. If excess topsoil exists beyond a depth of 8 inches, it shall also be removed from the site and not be used below building and pavement areas. The vegetation shall be stripped from building and pavement areas before site preparation, placement of utilities, excavation of soil cut, and placement of new fill. The entire root ball shall be removed below trees and shrubs. We understand that several trees will be removed for the building and grading areas, and that other nearby trees must not be disturbed. Be sure to advance sufficient excavation below trees in order to remove the entire root ball. Deeper stripping should be done if organic or deleterious materials remain and are encountered during site preparation.

The existing soil fill at this site is found to be variable. We recommend that all of the existing fill soil be excavated to expose the natural soils below. Our borings show that existing fill thickness varies from about 2 feet at the southwest building corner to 5.5 feet below existing grade at the northeast building corner. After the fill is completely removed, the natural soils shall be overexcavated to a level of 6.5 feet below the finished floor level. The overexcavation shall extend to a distance of at least 10 feet beyond the outer edges of the building. Suitable edge slopes shall be used for safety.

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After the overexcavations are complete within the building area and before any new fill clay is placed, a layer of manufactured sand shall be placed over the exposed subgrade. The purpose of this material is to hasten the rate of subsoils compression under the weight of the new fill and surcharge. Place a layer of filter geotextile upon the exposed subgrade, consisting of Mirafi 140N or equal approved by the geotechnical engineer. Place a layer of manufactured sand over this filter geotextile layer with a thickness of 8 to 10 inches. Pack it into place to a firm condition. We recommend the manufactured sand be crushed quartzite stone, or equal approved by the geotechnical engineer. If water collects within the base of the overexcavation, the contractor shall dick a sump hole at one corner of the excavation and divert all water by gravity to that location.

Use sump pump to remove the excess water. It is imperative that water from the subsoil or from rain is not allowed inundate the manufactured sand layer and soak up into the clay fill until the fill placement is completed to finished grade.

Compact the replacement structural fill over the manufactured sand, being careful to not mix the first lift of soil fill into the sand. Place the fill to finished grade by usual construction methods.

The recommended soil overexcavation is expected to impact underground electrical and communication lines to remain near the northwest corner of the building. These lines shall be protected or relocated.

Overexcavate below the carport and the exterior hall to the Administration Building, within the area near the Administration building to a depth of 2 feet below the top of soil subgrade level.

Additional fill thickness will result next to the new building area.

Remove the existing sanitary sewer pipe from below the building area and relocate it around the building area. Care shall be used in the relocation design so that any new fill placed above existing grade that is placed over the pipe does not cause the formation of a sag in the pipe due to subsoil consolidation. Existing utility lines shall be completely removed by excavation and the resulting trenches shall be filled to grade with properly compacted backfill, compacted in thin lifts to the requirements of structural fill.

A new parking lot will be constructed over existing grade to the southeast of the proposed building.

Up to 3 feet of fill above existing grade will be placed. We understand that the existing underground utility wires below this portion of the site will not be removed. We recommend that existing grade next to the street be overexcavated to a depth of 1 foot below base of pavement grade and replaced with new fill soil.

Building footings will be excavated into fill placed during site preparation. No additional subsoil preparation is recommended below the proposed footings.

It is expected that new utility pipes will be placed below the basement floor and that the floor subgrade will be disturbed by foundation excavations and by general construction traffic prior to placing the basement floor. Within 48 hours prior to poring the basement floor, the upper 12 inches of floor subgrade shall be scarified and compacted at a proper water content, and tested for proper compaction to determine that the floor subgrade is suitable for support of the new floor slab.

Swelling soils were not found at the borings. We find no reason to provide recommendation to mitigate potential effects of soil volume change due to high plasticity soil shrink and swell.

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3.4 Fill Requirements

Excavated topsoil materials are found to be unsuitable for reuse as compacted fill shall not be reused in new embankments or as fill below pavement areas. These soils can be reused as topsoil in landscape areas outside new pavement areas if they do not contain debris. All debris and deleterious materials shall be removed from the site.

Our boring data indicated that clean soil excavated from the site that does not contain topsoil or debris can be reused as compacted structural fill after the soil water content has been properly adjusted to the compaction requirements. However, all soil fill including on-site soils shall be approved by the geotechnical engineer prior to placement as compacted fill below buildings, sidewalks, and pavements.

The topsoil strippings will not be suitable for use in embankment fill and should be stockpiled for reuse in covering future vegetated portions of the site after grading activities are completed.

Reused soil generally provides greater resistance to water erosion on slopes and provides a better seedbed to grow erosion-resistant plants on slopes and across the entire site when compared to the soil below the topsoil. Excess stripping shall be removed from the site.

Material for use as site fill should be clean, inorganic, low-plasticity lean clay, CL1, or silt ML2, or a combination of these two materials both with a liquid limit less than 45 and a plasticity index less than 20.

Sandy or gravelly low to medium plasticity lean clay soils are also acceptable provided no more than 20 percent is retained on the No. 200 Standard US sieve and the sand and gravel are well and completely mixed into the soil. Any granular particles shall have a maximum dimension of 3 inches.

Sandy soils with classification of SM3, SC4, organic soils with classification OH5 or OL6, and highly plastic clays with classification of CH7 are not approved for general or structure fill below footings, against footings, as backfill, or below exterior pavements and sidewalks at this site. Use of sand as a fill material is not acceptable at this site, except for special drainage layers and a thin layer below interior floor slabs. The use of the layer of manufactured sand is described in the previous section of this Report, and sand shall not be used in any other location within the structural fill at this site.

A layer of sand is typically placed below interior floor slabs are part of the floor vapor barrier system. We understand that no other drainage or vapor retarding layers will be placed for this building, and therefore, no other sand layers shall be placed at other locations around the proposed building.

We recommend that an aggregate base layer not be used below the new pavements and sidewalks. No sand layer should be placed below exterior pavements and sidewalks, since no

1 Lean clay, lean clay with sand and sandy clay.

2 Silt, silt with sand and sandy silt.

3 Silty sand.

4 Clayey sand.

5 Elastic Silt 6 Organic Clay or Organic Silt 7 Fat clay, fat clay with sand, and/or sandy fat clay

10 September 1, 2016 exterior subgrade drain system will be installed. Sand below exterior pavements and sidewalks will only collect water and provide a means to slowly deteriorate the subgrade. Without exterior trench drains below pavements, water will simply stagnate in the granular base and provide a reservoir for future subgrade damage. No appreciable amount of water will seep through the compacted fill subgrade and be allowed to drain from granular base materials.

Proposed fill and backfill materials from onsite and from offsite sources shall be subject to approval by the geotechnical engineer. Representative samples of the proposed fill and backfill materials should be submitted to the geotechnical engineer at least three days prior to placement so the necessary laboratory tests can be performed.

Structural fill shall be cohesive soils consisting of lean clay and silt and shall have the proper water content at the time of compaction, within +3% and -3% of optimum water, per ASTM D698- 12e1, Standard Proctor. Water content shall be adjusted to a proper level before the soil is compacted into embankments.

All structural quality fill should be placed in nearly level lifts, not more than 8-inch loose thickness, after the water content has been manipulated to within the levels stated in the previous paragraphs. Each fill lift must be compacted to the necessary unit weight before additional soil is added. New structural fill below structures, pavements, sidewalks and in embankments shall be compacted to not less than 95% of the maximum dry unit weight determined by ASTM D698- 12e1, standard Proctor test. The upper 12 inches of subgrade below pavement and building floor slabs shall be compacted to at least 98% of the maximum dry unit weight determined by ASTM D698-12e1, standard Proctor test.

After fill placement, the rolling stability of the finished grade shall be evaluated using the “proof roll test”. The proof roll test is described in Section3.10 of this Report.

General fill in areas to support only vegetation should be compacted to not less than 85 percent and no more than 92 percent of the maximum dry unit weight determined by ASTM D698-12e1.

Topsoil should not be over compacted. Surface scarification may be required to allow initial root penetration. Tree root balls should not be placed into holes dug into compacted fill, but should be place on top of the grade with soil mounded around the root ball to allow drainage of excess water from around the roots until the roots can grow into the compacted soil fill.

When placing fill in narrow trench areas, the equipment used for compaction must be tailored to the width of that trench area. Compaction equipment must be no wider that half of the width of the excavation. If this condition is not being satisfied, the contractor shall obtain equipment of proper maximum width or shall over-dig the excavation to provide sufficient excavation width for his compaction equipment.

3.5 Backfill

Backfill clay and silt soils placed against footings, over utilities, and over drain pipes should also be of proper water content, within +3% and -3% of optimum water, per ASTM D698-12e1, Standard Proctor. We suggest that thin fill lifts be used and the excavation walls be properly braced or sloped in accordance with OSHA standards. All backfill around foundation elements shall be compacted to at least 95 percent of the maximum dry unit weight determined by ASTM D698-12e1, Standard Proctor. It is very important to provide this degree of compaction on the sides of buried pipes as well as the top of the pipe.

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Backfill over utility pipes placed in narrow excavations (no greater than 4 feet wide) shall be compacted to at least 90 percent of the maximum dry unit weight determined by ASTM D698- 12e1, Standard Proctor. This assumes the utility location has been previously filled to finished subgrade elevation prior to placing the excavated utility. The upper 12 inches of utility subgrade shall be compacted to at least 95 percent of the maximum dry unit weight determined by ASTM D698-12e1, Standard Proctor. For wide trench excavations, for excavations greater than 4 feet wide, the entire backfill shall be compacted to the requirements of structural fill found in Section

3.4 of this Report.

If soils excavated from the trench shall be reused for backfill, the soil shall be reviewed by the geotechnical engineer or his trained field personnel for acceptance by the geotechnical engineer.

3.6 Fill-Related Settlement and Soil Heave

Placement of soil fill upon any soil subgrade above the level of previous maximum soil surface elevations will cause the subsoils to compress or consolidate under the new soil weight. Soil fill will be placed above existing grade over the entire building area and over much of the proposed pavement areas. Fill of 1.8 to 10.3 feet above preconstruction grade will be placed over the building area. Fill of up to 3 feet above existing grade will be placed over the parking lot and the exterior hallway areas.

We estimate that no significant settlement due to consolidation under the weight of up to 3 feet of fill above existing grade will occur for the parking lot, the car port, or the connecting hallway to the Administration Building. No surcharge or weighting period between fill placement and construction are required for these three areas.

Based on data from similar soil types, consisting of lean clay loess, we have estimate the settlement that can be expected due to the fill placement. Significant settlement due to consolidation under the weight of the fill up to 10.3 feet thick will occur within the building area.

We estimate that 5 inches of subsoil compressions will occur due to the placement of 10.3 feet of fill. We recommend a combination of surcharge weight and waiting period to precompress the soils below the building area prior to construction. The surcharge shall cover the entire building area, and extend a distance of at least 10 feet beyond the edges of the building before the backslope to the finished exterior grade begins. At the northeast building corner the top of surcharge shall be placed to Elevation 1513 feet, and this elevation shall extend to a distance of 10 feet to the north and east from that corner. At the southwest building corner, the top of surcharge shall be at Elevation 1505 feet and extend at this elevation to a distance of 10 feet to the south and west of this building corner. Between the southwest and northeast building corners, increase the top of surcharge using a uniform gradient between Elevation 1505 and 1513 feet.

The slope of the top of surcharge slope within the building area shall roughly mimic the mirror image of the natural slope below. On the edges of surcharge, place a slope with maximum inclination of 1.5:1 to the edge of the fill slopes below.

Based on data from similar soils, we have estimate the time required to allow the subsoils to compress under the weight of the surcharge. The surcharge shall be left in place for a period of 105 days (3.5 months).

We recommend that the progress of the subsoil compression be monitored using three settlement plates. We recommend the placement of 4 settlement plates to monitor the settlement of the surcharge at this site.

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The site soils found at the boring locations consist of lean clay that has a low potential for shrink and swell. These soils are not anticipated to expand or swell due to the proposed excavation below grade to achieve the finished pavement elevations. No mitigation of soil swell is necessary to reduce heave potential, based on the soil data at the boring locations. The soils at the boring locations will not heave appreciably with normal annual changes in soil water content.

3.7 Foundation Recommendations

Shallow footings are recommended for support of building foundations. Site preparation recommendations are provided above.

3.7.1 Footing Depth, Frost Considerations. Exterior footings and interior footings not heated on all sides shall be placed at a depth of at least 60 inches (5 feet) below the lowest adjacent unheated or exterior grade to inhibit damage from frost action. Interior footings that exist completely surrounded by heated rooms may be placed at any convenient depth, as long as they bear at least 18 inches below the floor subgrade soil surface.

Structural stoops supported by footings shall be placed at all exterior swinging doors. An expansion joint of sufficient thickness that penetrates the pavement shall be placed at all locations where exterior pavements or sidewalks abut building walls or structural stoops.

Care shall be used to not allow exterior concrete to extend below siding or other exterior wall coverings. Stoop footings shall bear at the depth of the adjoining building footing.

3.7.2 Foundation Types. Based on the limited available data, shallow continuous or spread footing foundations are considered suitable for support of proposed new building and tunnel structure loads at this site. This statement assumes the site preparation and other recommendations of this Report are completed prior to footing installation.

3.7.3 Allowable Bearing Pressure. A net allowable soil bearing pressure of 2,500 pounds per square foot is available for support of normally constructed shallow footings on the existing glacial soils over all portions of the project. A factor of safety of 3 against general shear failure was utilized when calculating the soil bearing pressure. Footings shall be excavated into existing soils or into compacted structural quality clay fill with the excavation sides being the forms for the footing concrete.

After excavation, care should be taken to avoid wetting soils exposed at the base of the footings. Footing subgrade should not be allowed to freeze before or after footings are poured. Concrete should not be placed upon wetted soils. If rain or other surface water ponds on the exposed footing base soils, the geotechnical engineer shall be notified and be requested to provide suitable recommendations for construction, based on observed conditions at that time.

Conversely, it is also potentially damaging to the building to allow the soils at the base of the footing to dry prior to footing concrete placement. To reduce the potential for excessive wetting or drying of the foundation subgrade, we recommend the lower 8 inches of any footing excavation not be dug until the day the footing concrete will be poured or that the contractor protect the footing subgrade from weather conditions.

Construction during winter weather is a concern for shallow footings. Protect the subgrade of shallow interior footings placed above a depth of 5 feet from frost damage during winter construction until the building is properly heated.

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3.7.4 Lateral Earth Pressure. Soil resistance to lateral forces will depend upon the depth of the footing below frost action and other factors that seasonally loosen soils. The following lateral earth pressures, expressed as equivalent fluid pressures without a factor of safety, are recommended in design of foundation walls to support lateral loads:

Passive Resistance 180 pcf Active Pressure 50 pcf At-Rest Pressure 65 pcf

Adhesion at the base of the footings supporting lateral load is estimated to be 650 psf.

This adhesion value does not include a factor of safety.

The lateral load values provided here do not include water pressure loads. We are aware of no situation that would develop an unbalanced lateral water load against canopy footings below grade at this site. Footing drains are discussed on a separate Section of this Report.

3.7.5 Excavation Stability. The foundation excavations will generally extend into cohesive lean clay soils. We have no special excavation stability concerns with excavations within properly compacted fill. However, some of the site fill soils are very blocky. Blocks of soil could fall into the excavations. Clean all loose soil from the excavations before placing concrete. Clean sand fill should not be used, since excavations in clean sand will likely cave.

In any case, conform to the regulations provided by the U.S. Government and OSHA concerning excavation safety, 29 CFR Part 1926, Occupational Safety and Health Standards - Excavations. Our boring data indicated no sand will be encountered within proposed excavation depths. For the clayey fill expected to be found in the footing excavations at this site, the soil is estimated to generally classify as Type C per 29 CFR Part 1926, Occupational Safety and Health Standards – Excavations. Soil conditions vary and it is necessary for the contractor to have a trained person on-site during construction to determine the actual exposed soil type during excavation, with the authority to properly direct the excavation safety. The geotechnical engineer or any of his staff members is not this person.

3.7.6 Foundation Settlements. After settlement due to the subsoil consolidation caused by fill placement has been stabilized, foundation settlements of less than 1 inch total and less than ½ inch differential in a 30-foot span are estimated under the anticipated building loading, as assumed in this Report, using the net allowable bearing pressure listed above for shallow trench footings and column footings.

3.7.7 Foundation Excavations. Footing concrete shall be placed in freshly dug excavation trenches. The sides of the trench shall be the form for the footings, if the soil does not cave. Stem walls or column pedestals may extend above the top of footing level.

The contractor shall not place fill in footing trenches to correct over-digs or wrong footing placement. If the contractor cannot place extra concrete in these cases, the footing area of concern shall be completely filled with structural fill and then dug again after the excavation has been properly filled to the top of floor subgrade level.

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3.8 Foundation Drains

Footing drains shall only be installed to inhibit water migration to a subterranean space. A subterranean space will not be construction at this site. Therefore, footing drains shall not be installed around any portion of the proposed building areas.

3.9 Surface Drainage

Specific drainage paths will be determined for all surfaces. Be sure to keep water from ponding on grass and paved surfaces near or above the building and parking areas.

Temporary grades should be established during construction to prevent runoff from entering excavations. Backfill adjacent to the building and pavements should be placed as soon as concrete structural strength requirements are met, and should be graded to drain away from the building and pavements.

Final site grade should provide positive drainage away from buildings. For vegetation-covered areas a minimum gradient of 2.0 percent or about 1 inch per foot is recommended within 10 feet of the exterior of buildings. However, the slope may be decreased if the ground surface adjacent to the building is covered with concrete slabs or pavements. A minimum gradient of 0.5 percent is recommended for pavement surfaces next to and around buildings. The pavements should be slightly lower than the adjoining building floor and be constructed to allow for about 1 inch of normal winter frost heave in this area. Pavements and exterior slabs that abut the building should be carefully sealed against moisture intrusion at the joint.

3.10 Exterior Pavement and Sidewalk Recommendations

New pavement will be placed. Subgrade preparation recommendations are provided in Section

3.3 of this Report. All fill shall be properly compacted to structural fill quality.

Compact the upper 12 inches of pavement subgrade in thin lifts to least 98% of the maximum dry unit weight of the soil, as determined by ASTM D698-12e1, standard Proctor test. The water content of clay and silt soil being compacted should be within +3 and -3 percentage points from the optimum water content, also determined by ASTM D698-12e1.

Schemmer recommends the site pavement subgrade be final prepared with additional surface density compaction testing performed immediately prior to placing the pavement, within 48 hours of pavement placement. There is always the potential for rainfall or other inclement weather to occur between fill placement and pavement placement. If the soil surface is wetted by rainfall or disturbed in any way, the affected areas shall be scarified and compacted to the requirements of the previous paragraph.

A “proofroll test” is recommended to evaluate the stability of all pavement and floor slab subgrade.

Immediately prior to paving, the rolling stability of the pavement subgrade shall be evaluated in the presence of the geotechnical engineer or his trained representative through the rolling of a fully loaded tandem axle dump truck over the subgrade. The truck should hold at least 10 yards of soil during this proof roll test. As the truck is driven slowly back and forth across the subgrade, the engineer will observe the subgrade deflection and rebound under the loaded tires. If excessive deflection is observed, it is an indication that a portion of the subgrade is too wet or

15 September 1, 2016 otherwise unstable and that subgrade area will need to be overexcavated and replaced with properly conditioned and compacted subgrade soil fill.

We estimate the prepared subgrade consisting…