Attachment 4 - Geotech Report For Montrose WC.pdf

GEOTECHNICAL INVESTIGATION REPORT

USDA FOREST SERVICE – MONTROSE

PROPOSED GARAGE/STORAGE BUILDING

MONTROSE, COLORADO

Yeh Project No.: 218-256B

August 7, 2018

Prepared For:

J.F. Sato and Associates 5878 S. Rapp Street

Littleton, Colorado 80120 ATTN: Mr. Terry Wong, P.E., R.A.

Prepared By:

Yeh and Associates, Inc.

588 N. Commercial Dr.

Grand Junction, CO 81505

Phone (970) 242-5125 Fax (970) 255-8512

Attachment 4

1240LT22R0030

i

TABLE OF CONTENTS

1.0 PURPOSE AND SCOPE OF STUDY

2.0 PROPOSED CONSTRUCTION

3.0 SITE CONDITIONS AND GEOLOGIC SETTING

3.1 General Site Conditions

3.2 Site Geology

3.3 Radon Mitigation

4.0 SUBSURFACE INVESTIGATION

4.1 Field Exploration

4.2 Laboratory Testing

5.0 SUBSURFACE CONDITIONS AND SEISMICITY

5.1 Groundwater Conditions

5.2 Seismicity

6.0 FOUNDATION RECOMMENDATIONS

6.1 Spread Footings

6.2 Floor Slab Design and Construction

6.3 Exterior Slabs

6.4 Drainage

7.0 CONSTRUCTION RECOMMENDATIONS

7.1 Existing Structures

7.2 Site Grading Considerations

7.3 Subgrade Preparation

7.4 Fill Materials and Placement

7.5 Excavation and Trench Construction

7.6 Drainage Considerations

8.0 OTHER DESIGN CONSIDERATIONS

8.1 Water Soluble Sulfate

8.2 Corrosion Potential

9.0 LIMITATIONS

10.0 REFERENCES

ii

LIST OF FIGURES

FIGURE 1 – SITE LOCATION

FIGURE 2 – APPROXIMATE TEST HOLE LOCATIONS

LIST OF APPENDICES

APPENDIX A – TEST HOLE LOGS AND LEGEND

APPENDIX B – LABORATORY TEST RESULTS

APPENDIX C – RADON POTENTIAL MAP, MONTROSE COUNTY, COLORADO

Geotechnical Investigation Report Project No. 218-256B USDA Forest Service- Montrose, Proposed Garage/Shop Montrose, Colorado

1.0 PURPOSE AND SCOPE OF STUDY

This report presents the results of the geotechnical investigation by Yeh and Associates, Inc.

(YA) of subsurface conditions for the future placement of a garage/storage building at the USDA

Forest Service Montrose Administration site near Montrose, Montrose County, Colorado. The purpose of this study was to evaluate subsurface conditions within a 4,600 square foot area for foundation recommendations. Two test holes were drilled at the site to depths of refusal in dense material.

The study was performed in accordance with our proposal to Mr. Terry Wong with J.F. Sato and notice to proceed.

2.0 PROPOSED CONSTRUCTION

The new addition will be a single story, 4,600 square foot, pre-engineered metal garage/storage building to replace existing structures at the project site.

3.0 SITE CONDITIONS AND GEOLOGIC SETTING

3.1 General Site Conditions

The USDA Forest Service Montrose Administration site is located south of West Main Street, approximately 900 feet north of the intersection of 6400 Road and West Oak Grove Road, west of Sunset Mesa near Montrose, Colorado (see Figure 1). The project area is located east of the main driveway where there are existing structures as shown in Figure 2. Based on the USGS topography map for the Montrose West quadrangle, the elevation of the proposed storage site is approximately 5,820 feet and the topography of the general area slopes down to the northwest.

Based on onsite observations and survey, the project site is nearly level.

Adjacent to the project area to the north and east is irrigated agricultural land, with residential properties to the south and west. An irrigation ditch is located parallel to 6400 Road on the west side of the road. The Uncompahgre River is approximately 0.7 miles east of the project area and Happy Canyon Creek is approximately 0.7 mile west.

3.2 Site Geology

The project site is located in the Uncompahgre Valley in the trough of the Montrose Syncline at the west edge of the Colorado Plateau. Based on the 1986 geologic map of the Montrose West quadrangle, Montrose County, Colorado, surficial deposits at the site include clay, silt, sand and gravel of the Quaternary age alluvium and floodplain deposits of the Uncompahgre River.

Cobbles and boulders may be present. Other surficial deposits may include manmade artificial fill. Underlying the surficial deposits is the Cretaceous age Mancos Shale that is exposed in distant outcrops east and west of the project site. The shale weathers readily when exposed and forms yellow to gray soft slopes and hills.

There is a possibility that evaporite mineral and salt deposits, including sulfates such as gypsum, associated with the Mancos Shale may be present in the soils that underlie the project site. As per the Colorado Geological Survey website for corrosive soils, these minerals may be corrosive to buried metal and concrete. Based on the 2011 CGS Geohazard Mapping Project for Montrose County, the project area is located in a zone of low corrosive susceptibility for concrete. Results of corrosion testing on samples from the project site can be found in Section 7 below and in Appendix B.

The Mancos Shale may contain zones of swelling clays. The Colorado Geological Survey

(CGS) has identified areas of low swell potential and low collapsible soil susceptibility in the project area. These collapsible soils are associated with the alluvial and floodplain sediments derived from the Mancos Shale, a formation with high salt and gypsum content. Long term settlement resulting from soil consolidation can damage proposed structures that have foundations bearing in these soils.

3.3 Radon Mitigation

Based on the 2015 Montrose County Building Handout-Requirements for Frame Construction, Montrose County is listed as an area of high radon potential. The radon potential map for

Montrose County can be found in Appendix C. Radon testing is recommended by this document. A radon specialist should be contacted for testing for and mitigation of radon.

4.0 SUBSURFACE INVESTIGATION

4.1 Field Exploration

The scope of services performed for this project included a site reconnaissance by a representative of Yeh and Associates, a subsurface exploration, laboratory testing and engineering analysis

Two test holes (labeled TH-1 and TH-2) were drilled on July 3, 2018. The test holes were located in the field by measuring from existing features. A grade elevation survey of the test holes was performed by Yeh and Associates using stadia rod and transit method. A manhole cover near the south edge of the driveway and the east side of 6400 Road was used as a base elevation of 100 feet. Elevations measured of the test holes relative to this base showed TH-1 at

100.4 feet and TH-2 at 99.8 feet. The accuracy of test hole locations should only be assumed to the level implied by the method used. Test hole TH-1 was located near the southern edge of the proposed garage/shop. Test hole TH-2 was located near the northern edge of the proposed garage/shop. Utility locates were performed prior to drilling. Test holes were backfilled with cuttings and onsite native material. The locations of the test holes are presented in Figure 2 at the end of this report.

Both test holes were advanced with a Simco 2800 truck mounted rig using 4-inch solid-stem continuous flight auger. Test holes TH-1 and TH-2 were drilled to auger refusal in dense gravels at depths of 19.0 and 20.5 feet, respectively. At selected intervals, a modified California sampler with a 2-inch interior diameter (ID) and 2.5 inch outside diameter (OD), or a standard split spoon sampler with a 1⅜-inch ID and 2 inch OD were used to record blow counts and obtain samples.

The sampler was seated at the bottom of the test hole, then advanced by a 140-pound hydraulic automatic, or “auto,” hammer falling a distance of 30 inches (ASTM D1586). The number of blows required to drive the sampler 12 inches or a fraction thereof, constitutes the N-value.

The N-value, when properly evaluated, is an index of the consistency or relative density of the material tested. Samples obtained during the field explorations were examined by the project personnel and representative samples were submitted for laboratory testing to evaluate the subsurface characteristics of materials encountered. Test hole logs and legend are presented in

Appendix A, Laboratory test results are presented in Appendix B.

4.2 Laboratory Testing

Samples retrieved during the field exploration were tested by Yeh and Associates and were classified in accordance with the AASHTO and Unified Soil Classification Systems. (Colorado

Analytical, Denver, Colorado did the corrosion testing. An applicable program of laboratory testing was developed to evaluate engineering properties of the subsurface materials. Following the completion of the laboratory testing, the field descriptions were confirmed or modified as necessary and the boring logs were prepared.

Selected soil samples were tested for the following engineering properties:

• Moisture Determination

• Unit Weight

• Grain Size Analysis

• Atterberg Limits

• Water Soluble Sulfate

• Water Soluble Chloride

• pH

• Resistivity

The test hole logs and laboratory test results were used for the geotechnical engineering analyses and the development of foundation and earthwork recommendations. Laboratory tests were performed in general accordance with the applicable local or other accepted standards.

Details of laboratory test results are presented in Appendix B.

5.0 SUBSURFACE CONDITIONS AND SEISMICITY

The test holes were located near the perimeter of the proposed structure envelope. The test hole drilling indicate that the subsurface profile consists of approximately 1.0 to 1.5 feet of road base over 2.0 to 3.0 feet of dense to very dense sand and gravel to the full depth of exploration.

Practical drilling refusal was encountered in each test hole. No bedrock was encountered in either boring. One road base sample tested had 18 percent fines (material passing the #200 sieve), Atterberg limit testing that indicated a liquid limit of no value and plasticity index of non-plastic, classified as GM based on the Unified Soil Classification System (USCS), and as A-1-b based on the American Association of State Highway and Transportation Officials (AASHTO).

One native sand sample tested had 12 percent fines, a liquid limit of no value, a plasticity index of non-plastic, and classified as SP-SM (USCS), and as A-1-a (AASHTO).

5.1 Groundwater Conditions

Groundwater was not encountered in either of the test holes during the investigation. Variations in groundwater conditions may occur seasonally. The magnitude of the variation will be largely dependent upon fluctuations in the amount of spring snowmelt, duration and intensity of precipitation, site grading changes, local irrigation practices and the surface and subsurface drainage characteristics of the surrounding area. Seasonal perched areas of groundwater may also exist, but were not encountered in either of the test holes during the investigation.

5.2 Seismicity

Based upon the nature of the subsurface materials, a Site Class C should be used for the design of the structure for the proposed project (IBC 2012/2015, site coordinates: 38.46259° N, 107.89312° W). The project site is located in a seismic area with a mapped maximum short period (Ss) and 1-second period (S1) ground motion of 0.324 g and 0.083 g, respectively. The site coefficients Fa and Fv, for the same periods are 1.2 and 1.7, respectively

6.0 FOUNDATION RECOMMENDATIONS

The site appears suitable for the proposed construction based upon geotechnical conditions encountered in the borings. Based on the geotechnical engineering analyses, subsurface exploration and laboratory test results, we recommend that the proposed building structure be supported on a spread footing foundation system bearing on native soils. Design and construction details for the foundation options are given for Allowable Stress Design (ASD).

6.1 Spread Footings

As previously stated, spread footing foundation bearing upon undisturbed native soils and/or engineered fill is recommended for support of the proposed structure. The building footings may be designed for a maximum allowable bearing pressure of 3,000 pounds per square foot (psf).

The design bearing pressure applies to dead loads plus design live load conditions. The design bearing pressure may be increased by 1/3 or as allowed by local code when considering total loads that include wind or seismic conditions. Recommended minimum widths of column and wall footings are 24 inches and 16 inches, respectively.

Exterior footings should be placed a minimum of 2.5 feet below finished grade for frost protection and to provide confinement for the bearing soils. Interior footings should bear a minimum of 12 inches below finished grade. Finished grade is the lowest adjacent grade for perimeter footings and is floor level for interior footings.

Footings should be proportioned to reduce differential foundation movement. Proportioning on the basis of equal total movement is recommended; however, proportioning to relative constant dead load pressure will also reduce differential movement between adjacent footings. Total movement is estimated to be on the order of 1 inch or less. Differential movement should be on the order of ½ to ¾ of the estimated total movement. Additional foundation movements could occur if water from any source infiltrates the foundation soils, therefore, proper drainage should be provided in the final design and during construction.

Footings and foundations should be reinforced as necessary to reduce the potential for distress caused by differential foundation movement. The use of joints at openings or other discontinuities and at periodic intervals on long walls is recommended.

Foundation excavations should be observed by the geotechnical engineer. If the soil conditions encountered differ significantly from those presented in this report, supplemental recommendations will be required. Testing of materials used on site, such as concrete, as well as compaction testing on foundation soils by a representative of the geotechnical engineer is highly recommended.

6.2 Floor Slab Design and Construction

Non-expansive soils or engineered fill will support the floor slab. Some differential movement of a slab-on-grade floor system is possible should the subgrade soils become elevated in moisture content. To reduce potential slab movements, the subgrade soils should be prepared as outlined in Section 7.3 of this report.

loganfoster Highlight loganfoster Highlight

For structural design of concrete slabs-on-grade, a modulus of subgrade reaction of 200 pounds per cubic inch (pci) may be used for floors supported on native soils or imported fill meeting the specifications of Section 7.4.

Additional floor slab design and construction recommendations are as follows:

• Positive separations and/or isolation joints should be provided between slabs and all foundations, columns or utility lines to allow independent movement.

• Control joints should be provided in slabs to control the location and extent of cracking.

• Interior trench backfill placed beneath slabs should be compacted in accordance with recommended specifications outlined herein.

• In areas subjected to normal loading, a minimum 4-inch layer of sand, clean graded gravel or aggregate base course should be placed beneath interior slabs. For heavy loading, reevaluation of slab and/or base course thickness may be required.

• If moisture-sensitive floor coverings are used on interior slabs, consideration should be given to the use of barriers to minimize potential vapor rise through the slab.

• Floor slabs should not be constructed on frozen subgrade.

• Other design and construction considerations, as outlined in Section 302.1 R of the "ACI Design Manual", are recommended.

6.3 Exterior Slabs

On-site soils, whether in place or used in fills, may be susceptible to frost heave. There is the potential for frost to develop in the soils adjacent to the building during the winter season.

Covering of the native soils and/or introduction of moisture from irrigation or concentrated precipitation may increase the moisture content of the soils and result in frost heave. Therefore, movement may occur in exterior concrete slabs, which can result in off-sets, tilting and cracking.

The movement and cracking may affect the appearance and performance of the slabs and can affect the slab’s compliance with Americans with Disabilities Act (ADA) requirements. There are several mitigation measures to improve the slab’s appearance and performance; however, these options are not solely related to the geotechnical aspects so input from the design team is suggested. In areas where movement is to be mitigated we believe these options can be considered.

• The upper 6 inches of the native gravelly soils should be removed, processed and replaced at 90 percent compaction of a modified Proctor. We anticipate on site soils are suitable for construction.

• At entrances to the building, the exterior slab may be structurally tied to the building foundation. This detail would reduce offsets between the exterior slab and the building interior; however, the movement may be translated to other portions of the exterior slab.

The structural engineer should also include uplift loads from the exterior slab in designing the foundation.

• Moisture is one of the key elements; therefore, elimination of irrigation around the exterior slabs, directing roof discharges away from these slabs and preventing snow accumulation adjacent to the slabs can reduce the potential for movement.

• Use of plants that do not require irrigation and will help absorb the moisture beneath the exterior slab without creating large root masses, which could cause slab movement, may also reduce potential movement.

Yeh and Associates is available to discuss other options and the potential risk of exterior slab movement if requested.

6.4 Drainage

The subsurface consists of granular free draining material and no perimeter foundation drainage system is recommended at this time. If different soil conditions or groundwater are encountered during construction the geotechnical engineer should be contacted immediately and different recommendations may be made.

7.0 CONSTRUCTION RECOMMENDATIONS

The following presents recommendations for site preparation, excavation, subgrade preparation, and placement of engineered fills on the project.

Earthwork on the project should be observed and evaluated by Yeh and Associates. The evaluation of earthwork should include observation and testing of engineered fills, subgrade preparation, foundation bearing soils and other geotechnical conditions exposed during the construction of the project.

7.1 Existing Structures

Currently there are several storage buildings on concrete slabs in the proposed footprint of the new structure. The limits of foundation walls and footing under these buildings is unknown.

These foundations may need to be cut, drilled or demolished and removed completely for construction of the new structure and utilities. Leaving existing foundations in place is acceptable if they do not interfere with the recommendations listed herein.

7.2 Site Grading Considerations

Strip and remove existing vegetation and other deleterious materials from proposed building area. Stripped materials consisting of vegetation and organic materials should be wasted from the site or used to revegetate landscaped areas after completion of grading operations. All exposed surfaces should be free of mounds and depressions, which could prevent uniform compaction.

All exposed areas which will receive fill, once properly cleared, should be scarified to a minimum depth of 6 inches, conditioned to near optimum moisture content, and compacted. Based upon the subsurface conditions encountered, subgrade soils exposed during construction are anticipated to be relatively stable.

7.3 Subgrade Preparation

Subgrade soils beneath the footings and interior and exterior slabs should be scarified; moisture conditioned and compacted to a minimum depth of 6 inches. The moisture content and compaction of subgrade soils should be maintained until slab construction.

A sample of on-site material for re-use as fill was subjected to a Modified Proctor test and exhibited a maximum dry density of 135.2 pcf and an optimum moisture of 5.7 percent.

7.4 Fill Materials and Placement

Clean on-site soils or approved imported materials may be used as fill material. If unsuitable materials or construction debris are encountered in the footing excavations, they should be removed and replaced with engineered fill. Imported soils (if required) should be granular soils with no more than 35 percent passing the No. 200 sieve and a Plastic Limit of less than 15.

Import fill material should be reviewed by the geotechnical engineer prior to importing to the site.

Engineered fill should be placed and compacted in horizontal lifts of 8 inches or less, using equipment and procedures that will produce a uniform fill with the recommended moisture contents and densities throughout the lift. Recommended compaction criteria for engineered fill is 90 percent of the maximum dry density as determined by ASTM D1557, at a moisture content within 2 percent of optimum for granular soils.

7.5 Excavation and Trench Construction

Excavations into the on-site soils will likely encounter very dense conditions. All excavations must comply with the applicable local, State, and Federal safety regulations, and particularly with the excavation standards of the Occupational Safety and Health Administration (OSHA).

Construction site safety, including excavation safety, is the sole responsibility of the Contractor as part of its overall responsibility for the means, methods, and sequencing of construction operations. Yeh and Associates recommendations for excavation support is provided for the

Client’s sole use in planning the project, in no way do they relieve the Contractor of its responsibility to construct, support, and maintain safe slopes. Under no circumstances should the following recommendations be interpreted to mean that Yeh and Associates is assuming responsibility for either construction site safety or the Contractor’s activities.

We estimate the overburden soil encountered on this site will classify as a Type C material, or gravel, sand and silt existing as dry unstable rock using OSHA criteria. OSHA requires that unsupported cuts be no steeper than 1.5 H to 1 V for Type C material in unbraced excavations up to 20 feet in height. In general, we believe that these slope ratios will be temporarily stable under unsaturated conditions. Flattened slopes may be required if excavations encounter groundwater or the slopes will be exposed for an extended period of time. Please note that an

OSHA-qualified “competent person” must make the actual determination of soil type and allowable sloping in the field. The preliminary classifications presented above are based solely on the materials encountered in widely spaced exploratory test borings. The contractor should verify that similar conditions exist throughout the proposed area of excavation.

As a safety measure, it is recommended that all vehicles and soil piles be kept to a lateral distance equal to at least the depth of the excavation from the crest of the slope. The exposed slope face should be protected against the elements and monitored by the contractor on at least a daily basis.

7.6 Drainage Considerations

Positive drainage should be provided during construction and maintained throughout the life of the proposed project. Proper design of drainage should include prevention of ponding of water on or immediately adjacent to the structures. Surface features that could retain water in areas adjacent to the structures should be sealed or eliminated. In areas where paving does not immediately adjoin the structure, we recommend that, if feasible, protective slopes be provided with a minimum grade of approximately 5 percent for at least 5 feet. Backfill against any kind of structure and in utility line trenches should be well compacted and free of all construction debris to reduce the possibility of moisture infiltration and migration. Concentrated runoff should be avoided in areas susceptible to erosion and slope instability. Slopes and other stripped areas should be protected against erosion by re-vegetation or other method.

8.0 OTHER DESIGN CONSIDERATIONS

8.1 Water Soluble Sulfate

The concentrations of water-soluble sulfates measured in the laboratory on two samples taken at a depth of 3.5 feet in test hole TH-1 and at 0.5 feet in test hole TH-2 was 0.033 and 0.051 percent. This concentration of water-soluble sulfates represents a Class 0 degree of sulfate attack on concrete exposed to these geologic materials. The degree of attack is based on a range of Class 0 (negligible) to Class 3 (very severe) as described in the American Concrete

Institute (ACI) Standard 201.2R, “Guide to Durable Concrete”.

Based on these sulfate test results, the soils present a negligible potential for sulfate attack on concrete. Results of soluble sulfate testing indicate that ASTM Type I/II Portland cement may be specified for all project concrete on and below grade.

8.2 Corrosion Potential

Additional corrosion testing was performed on the selected samples. The pH, electrical resistivity and concentration of water-soluble chloride were determined for the same samples referenced above. Test results measured pH values of 7.0 and 7.2, resistivity of 329 and 334 ohm-centimeters, and water-soluble chloride concentrations were 0.0987 and 0.112 percent. A qualified corrosion engineer should review this data to determine the appropriate level of corrosion protection.

9.0 LIMITATIONS

The analyses and recommendations presented in this report are based upon our data obtained from the borings at the indicated locations, field observations, laboratory testing, our understanding of the proposed construction and other information discussed in this report. It is possible that subsurface conditions may vary between or beyond the points explored. The nature and extent of such variations may not become evident until construction. If variations in conditions from those described in this report appear, we should be contacted immediately so we can review our report in light of the variations and provide supplemental recommendations as necessary. Before any deviation from recommendations given in the report is taken we should be notified. We should also review the report if the scope of the proposed construction, including the proposed loads, finished elevations or structure design, change from those as described in this report. The conclusions and recommendations contained in this report shall not be considered valid unless Yeh and Associates reviews the changes and either verifies or modifies the conclusions of this report in writing.

We have prepared this report for the exclusive use of J.F. Sato & Associates for the proposed construction. The report was prepared in substantial accordance with the generally accepted standards of practice for geotechnical engineering as exist in the site areas at the time of our investigation. No warranties, express or implied, are intended or made. The recommendations in this report are based on the assumption that Yeh and Associates will conduct an adequate program of construction testing and observation to evaluate compliance with our recommendations.

The scope of services for this project did not include, specifically or by implication, any environmental or biological (e.g., mold, fungi, and bacteria) assessment of the site or identification or prevention of pollutants, hazardous materials or conditions or biological conditions. If the owner is concerned about the potential for such contamination, conditions or pollution, other studies should be undertaken.

10.0 REFERENCES

Colorado Geological Survey, Corrosive Soils, accessed web site August 1, 2018 at:

http://coloradogeologicalsurvey.org/geologic-hazards/corrosive-soils/

Colorado Geological Survey Earthquake and Cenozoic Fault and Fold Map Server, accessed web site August 1, 2018 at: http://dnrwebmapgdev.state.co.us/CGSOnline/

Hail W., 1986, Geologic reconnaissance map of the Montrose West quadrangle, Montrose

County, Colorado, U.S. Geological Survey, Open-File Report OF-86-163, scale

1:24,000.

Montrose County, November 2015, Montrose County Building Handout-Building Requirements for Frame Construction.

PROJECT NUMBER:

NOT TO SCALE

PROJECT:

FIGURE

DRAWN BY:

CHECKED BY:

DATE:

DATE:

DESIGNED FOR:

Consulting Engineers & Scientists Yeh and Associates, Inc. 1

JRM

SWR

07/17/2018

08/02/2018

J.F. Sato & Associates

218-256B

N

Base maps acquired from maps.google.com

Site Location Map

U.S. Forest Service Garage/Storage Building

Montrose, Colorado

SEE

BELOW

Montrose

Delta

Olathe

Site

S

R i o

G r a n d e

A v e

U n c o m p a h g r e

R i v e r

Oak Grove Rd

C h i p e t a

R d

R d

PROJECT NUMBER:

SCALE: 1"=30'

PROJECT:

FIGURE

DRAWN BY:

CHECKED BY:

DATE:

DATE:

DESIGNED FOR:

Consulting Engineers & Scientists Yeh and Associates, Inc. 2

JRM

SWR

07/17/2018

08/02/2018

J.F. Sato & Associates

218-256B

N

0 15 30 60

LEGEND

Indicates approximate location of test hole

Approximate Test Hole

Location Map

U.S. Forest Service Garage/Storage Building

Montrose, Colorado

NOTES: Base maps acquired from Google Maps.

Test hole borings were not surveyed at the time of the geotechnical report, and have been placed according to measurements taken in-field.

R o a d

TH-1

TH-2

TH-1

Driveway

Quonset Hut

Garage/Shed

Quonset Hut

Approximate location

Manhole cover benchmark

APPENDIX A

Test Hole Logs and Legend

A-1-a (0)

SP-SM

12 NPNV

pH=7 S=0.051% Chl=0.112% Re=334ohm·cm

3.5 ft - Auger refusal

44443.3 109.034-36-R R

0.0 - 1.0 ft. 12 inches Road Base, GRAVEL, silty with sand, loose.

1.0 - 4.5 ft. silty GRAVEL with silt and sand; cobbles and boulders may be present, brown, no plasticity, dry, very dense, Sand lenses or sand matrix may be present.

Bottom of Hole at 4.5 ft.

Total Depth: 4.5 ft

Ground Elevation: 100.4 ft

Coordinates: N: 1.0 E: 3.0

Location: East of driveway; 19.5 ft NNE of south Quonset hut

NW corner, 11.5 ft SE of SW corner of garage/shed Groundwater Levels: Not Observed

Logged By: K. Dye

Final By: J. Mulumba

Symbol

Depth

Date

Weather Notes: Partly Cloudy, 90°

Inclination from Horiz.: Vertical

Boring Began: 7/3/2018

Boring Completed: 7/3/2018

Drilling Method(s): Solid-Stem Auger (4" OD)

Driller: Colorado Drilling & Sampling

Drill Rig: Simco 2800

Hammer Type: Automatic (hydraulic)

Night Work:

Project Name:

PAGE

AASHTO

& USCS

Classifi-cations

F in e s C o n te n t

P la s ti c it y

In d e x

Project Number: 218-256B C o n s u l t i n g E n g i n e e r s & S c i e n t i s t s

L iq u id

L im it

Field Notes and

Other Lab Tests

USDA Forest Service Garage-Storage Building, Montrose

Atterberg Limits

Boring No.: TH-1

Yeh and Associates, Inc.

E le v a ti o n (f e e t)

D e p th

(f e e t)

S a m p le

T y p e

A d v a n c e m e n t M e th o d

B O

R

IN

G L

O G

-2

B

U S

F S

M O

N T

R O

S E

.G P

J

Y E

H A

S S

O C

IA

T

E S

T E

M P

L A

T E

.G D

T

L

IB

R A

R Y

.G L

B

/7

/1

S a n d C o n te n t

G ra v e l C o n te n t

M o is tu re

C o n te n t

D ry

D e n s it y

(p c f)Blows per 6 in

P e n e tr a ti o n R e s is ta n c e

L it h o lo g y

Soil Samples

Material Description

A-1-b (0)

GM

18 NPNV pH=7.2 S=0.033% Chl=0.0987% Re=329ohm·cm

2.0 ft - Auger refusal

32503.0

41-43-58 101

0.0 - 1.5 ft. 18 inches Road Base, GRAVEL, silty with sand, loose.

1.5 - 3.5 ft. GRAVEL with silt and sand;

cobbles and boulders may be present, brown, no plasticity, dry, very dense, Sand lenses or sand matrix may be present.

Bottom of Hole at 3.5 ft.

Total Depth: 3.5 ft

Ground Elevation: 99.8 ft

Coordinates: N: 1.0 E: 4.0

Location: N of TH-3; 31.5 ft NW of north Quonset hut, 25 ft S of north storage building SE corner Groundwater Levels: Not Observed

Logged By: K. Dye

Final By: J. Mulumba

Symbol

Depth

Date

Weather Notes: Partly cloudy, 90°

Inclination from Horiz.: Vertical

Boring Began: 7/3/2018

Boring Completed: 7/3/2018

Drilling Method(s): Solid-Stem Auger (4" OD)

Driller: Colorado Drilling & Sampling

Drill Rig: Simco 2800

Hammer Type: Automatic (hydraulic)

Night Work:

Project Name:

PAGE

AASHTO

& USCS

Classifi-cations

F in e s C o n te n t

P la s ti c it y

In d e x

Project Number: 218-256B C o n s u l t i n g E n g i n e e r s & S c i e n t i s t s

L iq u id

L im it

Field Notes and

Other Lab Tests

USDA Forest Service Garage-Storage Building, Montrose

Atterberg Limits

Boring No.: TH-2

Yeh and Associates, Inc.

E le v a ti o n (f e e t)

D e p th

(f e e t)

S a m p le

T y p e

A d v a n c e m e n t M e th o d

B O

R

IN

G L

O G

-2

B

U S

F S

M O

N T

R O

S E

.G P

J

Y E

H A

S S

O C

IA

T

E S

T E

M P

L A

T E

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S a n d C o n te n t

G ra v e l C o n te n t

M o is tu re

C o n te n t

D ry

D e n s it y

(p c f)Blows per 6 in

P e n e tr a ti o n R e s is ta n c e

L it h o lo g y

Soil Samples

Material Description

Project Number: 218-256B

USDA Forest Service Garage-Storage Building, Montrose

Legend for Symbols Used on Borehole Logs

Project:

Yeh and Associates, Inc.

C o n s u l t i n g E n g i n e e r s & S c i e n t i s t s

Lithology Symbols(see Boring Logs for complete descriptions)

Auger Cuttings Standard Penetration Test

(ASTM D1586)

Sample Types

Road Base GRAVEL with silt and sand; cobbles and boulders may be present

Lab Test Standards Other Lab Test Abbreviations Moisture Content ASTM D2216 Dry Density ASTM D7263 Sand/Fines Content ASTM D421, ASTM C136, ASTM D1140

Atterberg Limits ASTM D4318 AASHTO Class. AASHTO M145, ASTM D3282

USCS Class. ASTM D2487 (Fines = % Passing #200 Sieve Sand = % Passing #4 Sieve, but not passing #200 Sieve) pH Soil pH (AASHTO T289-91) S Water-Soluble Sulfate Content (AASHTO T290-91, ASTM D4327)

Chl Water-Soluble Chloride Content (AASHTO T291-91, ASTM D4327)

R-Value Resistance R-Value (ASTM D2844) Re Electrical Resistivity (AASHTO T288-91)

3. "ER" for the hammer is the Reported Calibrated Energy Transfer Ratio for that specific hammer, as provided by the drilling company.

2. The Modified California sampler used to obtain samples is a 2.5-inch OD, 2.0-inch ID (1.95-inch ID with liners), split-barrel sampler with internal liners, as per ASTM D3550. Sampler is driven with a 140-pound hammer, dropped 30 inches per blow.

1. "Penetration Resistance" on the Boring Logs refers to the uncorrected N value for SPT samples only, as per ASTM D1586. For samples obtained with a Modified California sampler, drive depth is 12 inches, and "Penetration Resistance" refers to the sum of all blows. Where blow counts were > 50 for the 3rd increment (SPT) or 2nd increment (MC), "Penetration Resistance" combines the last and 2nd-to-last blows and lengths; for other increments with > 50 blows, the blows for the last increment are reported.

Notes

APPENDIX B

Laboratory Test Results

(ohm-cm)

TH-1 3.5 SPT 3.3 109 44 44 12 NV NP NP 0.051 0.112 334 7.0 A-1-a (0) SP-SM SAND, with silt and gravel

TH-2

0.5-

1.0 Bulk 3.0 50 32 18 NV NP NP 0.033 0.0987 329 7.2 A-1-b (0) GM

ROAD BASE: GRAVEL,

silty with sand

0.5-

1.0 Bulk 5.7* 135.2**

ROAD BASE: GRAVEL,

silty with sand

218-256B

Sample

Type

Dry

Density

(pcf)

Gravel

> #4

Sand

Fines <

#200

LL

USDA Forest Service Garage/Storage Building, Montrose

PI

Grain Size Analysis Water

Soluble

Sulfate

Atterberg Limits

Depth

(ft) pH AASHTO Resistivity

YEH & ASSOCIATES, INC

Summary of Laboratory Test Results

Project Name:

USCS

Moisture

Content

Water

Soluble

Chloride

PL

Sample Location

Test

Hole

Material Description

Project No:

*Optimum Moisture Content-Modified Proctor

**Maximum Dry Density-Modified Proctor

SPT - Indicates Split Spoon sampler

Bulk - Indicates auger cuttings

NV - Indicates "No Value"

NP - Indicates "No Plasticity"

Drawn By: JM

Date: 07/13/18

Sieve

Size

Passing

3" -

2 ½" -

2" -

1 ½" -

1" 100

¾ " 82

½" 71

⅜" 67

#4 56

#10 41

#40 24

#200 12

Gravel (%) 44 LL NV Project Name:

USDA Forest Service Garage-

Storage Building, Montrose Yeh & Associates, Inc.

Geotechnical Engineering Consultants

Sand (%) 44 PL NP

Project No.: 218-256B Sample

Description:

SAND, with silt and gravel (SP-SM)

Checked By: SW Figure No.: B-1

Fines (%) 12

SIEVE ANALYSIS

Sample

Depth (ft.):

3.5PI NP

Sample ID: TH-1

0.010.11101001000

P e rc e n t P a s s in g

Particle Size (mm)

20040103/8" 41/2"3/4"3"12" 6" 1" 30 508 16

Sieve Analysis Hydrometer Analysis

Sieve Opening in Inches U.S. Standard Sieves Size of Particles in mm

1002"

Drawn By: JM

Date: 07/13/18

Sieve

Size

Passing

3" -

2 ½" -

2" 100

1 ½" 92

1" 92

¾ " 81

½" 69

⅜" 62

#4 50

#10 42

#40 31

#200 18

Gravel (%) 50 LL NV Project Name:

USDA Forest Service Garage-

Storage Building, Montrose Yeh & Associates, Inc.

Geotechnical Engineering Consultants

Sand (%) 32 PL NP

Project No.: 218-256B Sample

Description:

ROAD BASE: GRAVEL, silty with sand (GM)

Checked By: SW Figure No.: B-2

Fines (%) 18

SIEVE ANALYSIS

Sample

Depth (ft.):

0.5-1.0 BulkPI NP

Sample ID: TH-2

0.010.11101001000

P e rc e n t P a s s in g

Particle Size (mm)

20040103/8" 41/2"3/4"3"12" 6" 1" 30 508 16

Sieve Analysis Hydrometer Analysis

Sieve Opening in Inches U.S. Standard Sieves Size of Particles in mm

1002"

APPENDIX C

Radon Potential Map

Montrose County, Colorado

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Moderate radon potential (probable indoor radon average 2-4 pCi/L)

Map Of Radon Zones Fact Sheet

Purpose o Sections 301 and 309 of IRAA directed EPA to list and identify areas of U.S. with the potential for elevated indoor radon levels.

• EPA's Map of Radon Zones assigns each of the 3,141 counties in the United States to one of three zones based on radon potential.

o Zone I counties have a predicted average indoor screening level greater than 4 pCi/L (red) o Zone 2 counties have a predicted average screening level between 2 and 4 pCi/L (orange) o Zone 3 counties have a predicted average screening level less than 2 pCi/L (yellow)

Audience

• National, state and local governments and organizations:

o to assist in targeting their radon program activities and resources.

• Building code officials:

o to help determine areas that are the highest priority for adopting radon-resistant building practices.

Map Development

• Five factors were used to determine radon potential:

o indoor radon measurements; geology; aerial radioactivity; soil permeability; and foundation type.

» Radon potential assessment is based on geologic provinces:

o Radon Index Matrix is the quantitative assessment of radon potential, o Confidence Index Matrix shows the quantity and quality of the data used to assess radon potential.

• Geologic Provinces were adapted to county boundaries for the Map of Radon Zones.

Map Documentation

• Detailed booklets are available for every state:

o Booklets discuss the matrices and data used in every state.

• State booklets are an essential tool in employing the maps' information.

Important Points

• All homes should test for radon, regardless of geographic location or zone designation.

• There are many thousands of individual homes with elevated radon levels in zones 2 and; 3. Elevated levels can be found in zone 2 and zone 3 counties.

« All users of the map should carefully review the map documentation for information on within-county variations in radon potential and supplement the map with locally available information before making any decisions.

• The map is not to be used in lieu of testing during real estate transactions.