B08_Attach 3 Report 1_Subsurface Exploration and Foundation Recommendations.pdf

Correct Structural Deficiencies & Stabilize Steel Visitor Center Crater Lake, Oregon

Subsurface Exploration and Foundation Recommendations

NPS Document Number:

106/144027

PMIS No. 198641

December 3, 2018

FINAL Subsurface Exploration and Foundation Recommendations December 3, 2018 Correct Structural Deficiencies & Stabilize Steel Visitor Center Crater Lake, Oregon

TABLE OF CONTENTS

Page

Page i

1.0 INTRODUCTION

1.1 Project Description

1.2 Scope of Work

1.3 Background Review

2.0 PHYSICAL SETTING

2.1 Area Topography and Development

2.2 Regional Geology

2.3 Seismic Risk

2.4 Volcanic Risk

2.5 Climate

3.0 FIELD EXPLORATION AND LABORATORY TESTING

3.1 Field Exploration

3.2 Laboratory Testing

4.0 SITE CONDITIONS

4.1 Subsurface

4.2 Groundwater

5.0 ENGINEERING ANALYSIS

5.1 Foundations

5.1.1 Bearing Capacity

5.1.2 Settlement

5.1.3 Foundation Drainage

5.2 Seismic Design Criteria

5.2.1 Site Stability and Liquefaction

5.3 Earthwork

5.4 Dewatering

5.5 Seasonal Frost Protection

5.6 Earth Pressures

6.0 RECOMMENDATIONS

6.1 Foundation

6.1.1 Bearing and Settlement

6.2 Earthwork

6.3 Dewatering and Drainage

6.4 Seasonal Frost Protection

6.5 Earth Pressures

7.0 LIMITATIONS

8.0 REFERENCES

TABLE OF CONTENTS (continued)

Page ii

FIGURES Page

Figure 1: Topography around the Ranger Dormitory, 1932

TABLES

Table 1: Average Monthly Temperatures and Snowfall Table 2: USGS Design Maps Summary Report (USGS 2018) Table 3: Footing Design Criteria Summary

APPENDICES

Appendix A ............................................................................................. Test Boring Location Map Appendix B ...................................................................... Test Boring Logs and Descriptive Guide Appendix C ............................................................................................... Laboratory Test Results Appendix D ........................................................................................ USGS Seismic Design Data Appendix F ............................................................................................................. BERG2 Results

1.0 INTRODUCTION

The National Park Service (NPS) plans to structurally improve and seismically retrofit the Steel

Visitor center located in Crater Lake National Park in Crater Lake, Klamath County, Oregon. The purpose of this geotechnical engineering report is to support the design and construction of the proposed improvements. This report presents the results of our field exploration, laboratory soil testing program, and geotechnical engineering recommendations for the foundation design and construction considerations. This work was completed for RIM Architects on behalf of the National

Park Service. The site location is shown in the Site Vicinity Map, Appendix A.

1.1 Project Description

Originally built in 1932 as the Ranger’s Dormitory Building, the building was converted into the

Steel Visitor Center in 1986 and is included in the Munson Valley Historic District listing in the

National Register of Historic Places. The Munson Creek Valley can experience up to 20 feet of snowfall in a season and over the years this has caused structural damage to the visitor center building. In 2011, temporary shoring was placed in the structure for it to safely continue operating.

The purpose of this project is to correct structural deficiencies, provide code improvements to fire suppression, electrical, mechanical systems, and the building envelope. Improvements to the foundation may be necessary to improve lateral resistance to uneven snow loads and seismic loads.

This report is valid only for the planned improvements as they are currently understood. Changes to the scope may impact the recommendations contained herein and should be evaluated by the project geotechnical engineer.

1.2 Scope of Work

DOWL provided geotechnical proposal details to RIM Architects who submitted a proposal on

April 27, 2018 in response to the NPS IDIQ for Architectural and Engineering Services scope of work. The proposal included geotechnical engineering services consisting of subsurface exploration by drilling and sampling test borings, performing laboratory testing, engineering analysis, report preparation, and providing geotechnical engineering recommendations.

In brief, the geotechnical scope of work included:

Review of the available background information;

Pre-design kick off meeting at Crater Lake Park;

Providing a subsurface exploration including two 50-foot borings;

Performing various laboratory soils testing;

Providing engineering analysis to support the structural improvements; and

Preparing a report of findings and recommendations.

Our proposal was accepted in April 2018, however, Notice-to-Proceed was received September

12, 2018 due to permitting for the subsurface exploration.

1.3 Background Review

DOWL reviewed several historical drawings, plans, repair documents, and shoring calculations provided by NPS. The reports provided details on the structure, utility locations, and drains;

however, subsurface data for design was not available. After the on-site kick-off meeting, NPS requested that DOWL provide a geotechnical work plan for the proposed drilling. After reviewing the background information and the project site, the subsurface conditions were anticipated to be granular with large cobbles or boulders with potentially shallow groundwater due to the location of Munson creek north of the building. The depth to bedrock was unknown. Based on the anticipated ground conditions, the subsurface exploration program was designed to collect samples using a split-spoon sampler and/or rock core.

2.0 PHYSICAL SETTING

The Steel Visitor Center site is located southwest of Crater Lake in the Munson Valley, Site Vicinity

Map, Appendix A.

2.1 Area Topography and Development

The visitor center is located within the Munson Valley village developed early in the 20th century as a ranger dormitory in the park headquarters. The site topography remains much the same as it was when developed in 1932, Figure 1. The area is forested with large boulders and steep slopes to the north and east. The area immediately around the building gently slopes toward

Munson Creek, which drains the valley and generally flows westward.

Figure 1: Topography around the Ranger Dormitory, 1932

Utilities run from the east to the north side of the covered walkway and building. The parking and entry areas drain into storm drains that flow along the western side of the structure.

2.2 Regional Geology

The Steel Visitor Center is located in Munson Valley of Crater Lake National Park, a glacially formed valley on south slope of Mount Mazama which violently erupted 7,700 years ago leaving a collapsed caldera that now contains Crater Lake (NPS, 2013). Crater Lake National Park lies in the Klamath Graben, a north-south trending fault block valley that is part of the West Klamath

Fault Zone, and it is the western-most basin of the Basin and Range physiographic province. Due to this setting, the region is dominated by normal faults, caused by Basin and Range extension, and is subject to potential damaging earthquakes in the park due to ongoing rifting. The region is also subject to the Cascadian fault system where oceanic crust subduction under the North

American Plate and the movement of magma that can both generate seismic and volcanic activity.

The geology of the Crater Lake area is very complex and consists of interlayered eruptions of basalt, andesite, dacite and rhyodacite starting 420,000 years ago and continuing in regular pulses until the climactic event 7,700 years ago (Bacon and Wright 2017). Mount Mazama was around 12,000 feet high at its’ zenith and it is both a shield volcano containing mafic lavas as well as a stratovolcano, with layers of silicic lavas, lahars, and pyroclastics. Due to the plate tectonic setting of Crater Lake, the region has potential for both seismic activity due to the rifting of plates and volcanic activity due to active subduction and the feeding of a magma chamber.

Prior to the massive caldera-producing eruption, Mount Mazama contained glaciers that carved large U-shaped valleys on all sides of the volcano. Some of these valleys were completely or partially infilled by lava and ejecta and others were filled primarily with slope wash, stream alluvium, and materials transported into the valleys by gravity over time. Locally, Munson Valley was carved by glaciers, as evidenced by the U-shaped valley profile that was partially filled with lithic breccias and ignimbrites (pumice, scoria, tuff, pyroclastic material) and then covered with a wedge of colluvium and alluvium (Bacon 2008). The two boreholes drilled to 50 feet at the Steel

Visitor Center indicated valley fill to this depth. The soils are dominated by sand to silty sand with sub-rounded to angular volcanic rocks (gravel to boulder-sized) of mixed lithologies. Due to glacial scouring, depth to bedrock could be quite deep at this site and should not be regarded as present for foundation support.

2.3 Seismic Risk

Sources of seismic activity that have the potential to affect the Steel Visitor Center and Crater

Lake National Park are the West Klamath Lake fault zone, Cascadia subduction zone, and local volcanic earthquakes (NPS 2013). The West Klamath fault zone consists of multiple faults, one of which (the Annie Spring fault) is less than 1-mile west of the Steel Visitor Center (USGS 1997).

Although earthquakes on this fault system can be as large as magnitude M7.25, their recurrence interval is once in 3,000 to 10,000 years; however smaller earthquakes are much more likely

(Bacon 2008). An additional source of seismic activity is the Cascadia subduction zone, although more distant, has the potential to generate magnitude (M) 8 to 9 earthquakes. For local volcanic earthquakes, there is the potential for ground motion at Crater Lake on the order of M5. Larger earthquakes can cause structural and cosmetic damage to structures, but they can also trigger landslides and rockfalls on steeper slopes.

2.4 Volcanic Risk

Volcanic eruptions have been occurring at Mount Mazama for over 400,000 years, so it has a long history of basaltic, andesitic and rhyolitic eruptions due to the active subduction zone setting and Basin and Range rifting of the site (USGS 1997). Although the climactic eruption 7,700 years ago that resulted in the caldera collapse appears to have been the most recent large-scale eruptive event of the volcano, there have been more recent eruptions on the lake floor and active hydrothermal vents have been observed in these areas. Although the USGS (1997) indicates there is not a large magma chamber currently developing under Crater Lake, there is the potential for three types of eruptions at Crater Lake: large pyroclastic eruption or pyroclastic surges in shallow or deep water, sudden release of lethal carbon dioxide or other gases from vents in the lake, and catastrophic draining of the lake due to breaching of the caldera wall. Any of these events could also trigger slope failures due to volcanic activities. According to the USGS Volcano

Hazards Program (2018), the volcanic threat potential for Crater Lake is considered very high. As such, Crater Lake is on the “Highest Priority” list for regional volcano monitoring.

2.5 Climate

Crater Lake National Park lies in the Cascade Mountains at a high elevation in a Mountain climate heavily influenced by warm, moisture air moving east from the Pacific Ocean. This air movement is the source for heavy snowfall at the project site. The NOAA 100-year Design Air-Freezing Index

(F100) for Crater Lake Headquarters is 1,430 degree days (F-day). Climate data for the monthly average high and low temperatures, snowfall, and snow depth for the period between 1931 and

2017 are shown in Table 1.

Table 1: Average Monthly Temperatures and Snowfall

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Average Daily

High (°F) 34 35 37 42 50 58 69 69 63 52 40 34

Average Daily Low (°F) 18 18 19 23 28 34 41 41 37 31 23 19

Average Snowfall* (in.) 100 81 83 45 19 4 0.2 0.1 3 21 61 93

Average Snow Depth*

(in.)

79 101 115 111 76 24 1 0 0 2 16 47

*Source: National Park Service 10-9-18 (https://www.nps.gov/crla/planyourvisit/weather.htm)

3.0 FIELD EXPLORATION AND LABORATORY TESTING

3.1 Field Exploration

The test boring exploration for the Steel Visitor Center project was conducted on September 12, 2018. The test borings were drilled, sampled, and logged to depths of 52 feet outside of the building footprint at the southeast and northwest corners.

The test borings were located in the field to avoid existing buried utilities and to be relatively close to the existing structure to sample relevant soil types. The locations of the test borings are shown on Figure 2, Test Boring Location Map, located in Appendix A.

The test borings were drilled using a CME-85 truck-mounted drill rig fitted with continuous-flight, 8-inch hollow-stem augers. The rig is owned and operated by HazTech Drilling, Inc. The drilling was supervised, and the samples logged by Laurie Brandt, CPG, a geologist with our firm.

Grab samples were obtained at the surface where each test boring was drilled. Disturbed samples were generally obtained at 5-foot intervals using a standard split-spoon sampler, as indicated on the borehole logs.

The Standard Penetration Test (SPT) was performed in the test borings by driving either a

Standard or a modified California (2.5-inch inside-diameter), split-spoon sampler a distance of 18-inches ahead of the auger with a 140-pound hammer falling 30 inches in general accordance with

ASTM Standard Test Method for Standard Penetration Test and Split-Barrel Sampling of Soils

(D1586). The standard penetration resistance (N) value shown on the test boring logs indicates the number of blows required to drive the sampler the last 12 inches. The results are an indication of the relative density or consistency of the subsoil. The N-values shown in the logs are raw data from the field and have not been adjusted for sampling equipment type, adjusted for sampler size, or overburden pressure.

Soil samples recovered during drilling were visual-manually classified in general accordance with

ASTM D2488 and sealed in plastic bags to preserve the natural water content. The samples were then transported to DOWL’s Montrose, Colorado laboratory in accordance with ASTM D4220, for further testing. No environmental testing or monitoring was conducted as a part of this investigation.

3.2 Laboratory Testing

Laboratory tests were performed on selected samples to measure soil index properties to provide a basis for estimating engineering properties. Soil index testing included moisture contents, Atterberg Limits, and Gradation Analysis performed on selected samples. The natural water content of nearly all the recovered samples was measured.

Soil samples will be stored until December 2018, after which time they will be discarded unless other arrangements are made.

Moisture Content. The natural moisture content of most recovered samples was determined in accordance with ASTM D2216; except, due to limited sample sizes, some tests may have been performed on samples smaller than the minimum test size required by the standard. The water contents are reported on the graphic test boring logs, Appendix B.

Particle Size Distribution Tests. Twelve particle-size distribution tests were performed on selected soil samples in accordance with ASTM D6913 and D1140. These tests consisted of mechanical sieving and the results are presented graphically in Appendix C.

Atterberg Limits. Two Atterberg Limits tests were performed in accordance with ASTM D4318, multipoint method A. The liquid limit, plastic limit, and plasticity index numbers obtained from the test are used to classify the soil fines as silts or clays. In addition, the limits can be used to estimate strength and settlement characteristics of soils. The results of the plasticity index tests are presented on the test boring logs in Appendix B and summarized in Appendix C.

4.0 SITE CONDITIONS

This section reports interpretations and opinions concerning the surface and subsurface soil and groundwater conditions at the site. The site conditions described are valid for the data collected within the scope of work. If additional data becomes available, interpretations and opinions expressed herein could change. We should be notified immediately if the conditions found at the site are different from those encountered during this investigation.

The soil descriptions and stratigraphy contained herein, and the classifications shown on the test boring logs are the project geotechnical engineer's interpretation of the field logs and the results of the laboratory soil testing. The largest particle size that can be recovered with standard drill hole samplers is often smaller than the maximum particle size in a gravelly soil deposit. Therefore, the soil descriptions and test results for gravelly soils tend to be biased toward the finer particle sizes.

Refer to the Test Boring Log - Descriptive Guide in Appendix B immediately following the test boring logs for a more detailed presentation on sample sizes, sample quality, frost classifications, soil types, and the soil classification procedures.

4.1 Subsurface

In general, the soils at the Steel Visitor Center consist of sand to silty sand with rocks varying in size from gravel to small boulders. In the upper 28 feet in Test Boring 1 (BH #1) and 34 feet in

Test Boring 2 (BH #2), the soils are red-brown, dark brown, and gray-brown, sandy gravel to silty sand with gravel that are moderately dense to very dense. BH#2 was generally more gravelly that

BH #1. BH #2 was moved slightly when a boulder was encountered at 6 feet. Additionally, a boulder at 22.5 feet in BH #2 caused auger refusal by 26.5 feet and the drilling method was changed to HQ coring to penetrate the rock. The far side of the boulder was reached at 27.2 feet and gravels extended to 34 feet. For the sandy gravel, uncorrected blow counts were greater than

50 blows per foot (bpf) in both borings. Below 28 feet in BH #1 and 34 feet in BH #2, the soil was predominately coarse sand with some fines and occasional small gravels. Uncorrected blow counts in this lower stratum ranged from 5 to 16 bpf. Groundwater was encountered at 45.5 feet in BH #1 and groundwater was not observed in BH#2 because water was introduced to aid in the coring process. Groundwater appears to be deep due to the granular and permeable nature of the soils.

4.2 Groundwater

The depth to groundwater was measured in BH #1 to be 45.5 feet below existing grade at the time of drilling. Groundwater was not observed in BH #2 due to the use of water while rock coring.

The water level is expected to fluctuate due to seasonal runoff. For more accurate water levels, a long-term monitoring well is necessary.

5.0 ENGINEERING ANALYSIS

The following sections discuss the project’s design considerations; see the Recommendations section for geotechnical engineering recommendations.

5.1 Foundations

The existing building is supported on a rock and mortar footing buried approximately 1.5 to 2.5 feet below the ground surface (Scoping Report 2013). It is feasible to support the existing building on conventional spread footings if placed on native mineral soil or structural fill as defined in the recommendations section. The preliminary foundation improvement design is to excavate approximately 1.5 feet below the existing footing for a span of several feet and construct and pour the concrete footing. The width of the footing is anticipated to be 3 or 4 feet across to support the overlying rock walls.

5.1.1 Bearing Capacity

The dense sand and gravel soils in the upper 20 feet of the soil column can support bearing loads if backfilled with properly compacted structural fill or onsite sandy gravel. Footings should bear on dense, native sand or gravel, or if overexcavated, should be replaced with dense structural fill. A factor of safety of 3 was used and provided limited burial depths and sizes, an allowable bearing pressure of 4,000 pounds per square foot (psf) is achievable and additional bearing pressure could be obtained with increased depth. Footing size, burial, and allowable bearing capacity are presented in the recommendations section.

5.1.2 Settlement

Care must be taken to avoid loosening the bearing surface underlying existing footings as recompacting or tightening the footing subgrade below the existing perimeter footing may not be possible with conventional compaction equipment. Loose soil or areas below existing footings should be removed and filled with concrete or if a significant volume is overexcavated, flowable fill (self-compacting low strength material, 100 to 300 psi compressive strength) should be used if structural fill cannot be properly placed and compacted. Bearing on medium dense to dense native sand and gravel or properly compacted structural or flowable fill, a total settlement of 1 inch or less and a differential settlement of 0.5 inch or less can be anticipated.

5.1.3 Foundation Drainage

The existing basement has reportedly not had water issues or drainage in the past. If the basement is expanded toward the perimeter footing, an exterior or interior foundation drain may be necessary during spring runoff to protect the basement space from water infiltration. The drain may be too low to tie into the sewer system and would require a sump and pump.

5.2 Seismic Design Criteria

The site was characterized in accordance with ASCE 7-10 Site Class Definitions based on the average properties in the top 100 feet of the soil column. The standard penetration resistance or

N-value can be correlated to the soil shear wave velocity which defines the classification from A to F, for further details please refer to the ASCE 7-10 reference. The average N-value encountered was between 15 and 50 which correlates with a seismic site class D. The subject site was explored to a depth of 52 feet, however, it is anticipated deeper soils will maintain or increase in relative density and soil shear wave velocity. Based on these parameters, the seismic site class D is an appropriate classification.

Mapped acceleration parameters, site coefficients, and adjusted maximum considered earthquake spectral response acceleration parameters for this site have been determined using the United States Geological Survey (USGS) Design Maps application based on the ASCE 7-10, seismic site class D, and an assumed Occupancy Level I, II, or III and are summarized in Table

2. The USGS summary and detailed reports, as well as, ASCE 41 summary sheets are attached in Appendix D.

Table 2: USGS Design Maps Summary Report (USGS 2018)

SS 0.552 g SMS 0.750 g SDS 0.500 g S1 0.268 g SM1 0.500 g SD1 0.333 g

Mapped MCE PGAM 0.312 g

5.2.1 Site Stability and Liquefaction

A stability evaluation for the subject property for the potential of ground failure due to earthquake-induced slope instability, loss of bearing capacity, liquefaction, and lateral spreading on and about the site has been performed in accordance with Section 11.8.1 of ASCE 7-10.

Liquefaction. Liquefaction is the partial or total loss of strength of soils that can occur during strong earthquake shaking of significant duration. Earthquake-induced liquefaction generally occurs only under particular conditions including high groundwater table, strong earthquake ground shaking of long duration, and loose uniform sands. Typically, liquefaction occurs where the groundwater table is shallow (5 to 10 feet deep) and generally only at depths less than about

50 feet. At this site, ground water was not encountered while drilling until 45.5 feet in BH #1 and groundwater was not observed in BH #2. Given the depth to groundwater, this site has a low probability of liquefaction in a design earthquake.

Slope Instability. This site is located on a gently sloping area and there are no retaining walls or long-term engineered slopes; therefore, seismic slope instability is not applicable to this project.

Loss of Bearing Capacity. Based on the soils and blow counts, if a large-scale magnitude earthquake were to affect the site, significant loss of bearing at this site is not likely to occur.

Land Spreading. It is unlikely that area-wide ground stretching would occur.

5.3 Earthwork

Existing Fill. Existing fill was not documented due to the granular soil but should be anticipated in the upper 3 feet as backfill for the foundation. The fill material contains non-frost susceptible gravel in BH #1 and potentially frost susceptible sand with gravel in BH #2. For uniform frost protection, the structural backfill should be non-frost susceptible gravel particularly in areas that where snow removal is desired.

Cut Slopes. Temporary cut slopes for utility trenches and for foundation excavations in both granular and fine-grained soils have been known to stand temporarily at very steep angles;

however, they also have been known to fail suddenly, without warning, claiming lives. It is the responsibility of the contractor to determine appropriate temporary cut slopes or shoring for excavations and trenches for the site soils, and surface loading conditions. As a minimum, the contractor should be in full compliance with all federal, state, and local safety requirements for trenching and shoring.

5.4 Dewatering

Based on the measured depth to the groundwater of approximately 45.5 feet below the surface, construction dewatering of groundwater may not be necessary on this site; however, the groundwater data was collected at a seasonal low and may be seasonally perched or influenced by snowmelt or spring runoff. Excavations must be protected from melting snow runoff and precipitation events. It is essentially impossible to adequately place and compact structural fill if there is standing water in the excavation. Dewatering the excavations until they are properly backfilled is necessary.

5.5 Seasonal Frost Protection

Frost action in seasonally frozen ground can subject foundations and structures to large uplift forces and destructive movements. Freezing and thawing of structural fill can reduce the density of the fill to less than the minimum density required for adequate support of structural loads.

Analysis using BERG2 was performed on the NOAA 100-year design freezing index (Appendix

F). Seasonal frost can be expected to penetrate 5 to 6 feet at this site in a cold winter without snow cover. Most of the structure is likely protected due to significant snow cover; however, the covered walkway, sidewalks, or cleared parking areas will have deeper frost penetration.

Typical methods of dealing with seasonal frost problems are to keep to bearing soils thawed by heating, insulating, and/or using an appropriate depth of bury and/or designing the structure to accommodate the anticipated frost heave. Based on our understanding of the site soils and the planned development, an appropriate frost protection scheme is presented in the

Recommendations section of this report.

5.6 Earth Pressures

Lateral earth pressures against foundation walls may be relied upon to resist lateral loads against the building. The magnitude of lateral earth pressure is a function of the type and density of the soil adjacent to the subgrade wall or footing; the height of the groundwater table adjacent to the structure; and the allowable movement of the structure with respect to the backfill. Design values for the classic "active,” "at rest,” and "passive" earth pressure conditions and seismic earth pressures are presented in the recommendations section of this report.

6.0 RECOMMENDATIONS

These recommendations are based on professional judgment and experience and the data collected during the site exploration and soil laboratory tests. These recommendations generally are not the only design options available; there may be several acceptable alternatives. These recommendations are not intended to represent the only way, but rather to indicate one appropriate option based on the information available.

6.1 Foundation

Improving the existing structure’s rock and mortar foundations with reinforced conventional spread footings is feasible bearing on native mineral soil or structural fill.

6.1.1 Bearing and Settlement

The footings may be designed for a maximum allowable soil bearing pressure of 4,000 psf. The minimum width of continuous strip footings should be 16 inches and the minimum width of isolated rectangular footings should be 18 inches. The allowable soil-bearing pressure may be increased by one-third for wind and seismic forces. Perimeter footings should be founded at least 36 inches below the adjacent exterior grade assuming the building is kept warm year-round and not allowed to freeze. Additionally, all interior footings should be founded at least 18 inches below the lowest adjacent grade unless constrained by the floor slab.

Exterior or cold, isolated footings should be founded a minimum of 72 inches below the adjacent grade for frost protection. As an option, the cold footing may be founded 60 inches below adjacent grade with a minimum of 18 inches of NFS structural fill below the footing and should also be protected by 2 inches of closed-cell extruded polystyrene (EPS) insulation placed at least 18 inches below the ground surface and extending 24 inches, minimum, from the footing edge.

Expected differential movement at the edges of the insulation due to frost heave can be addressed by tapering the insulation either in thickness or in depth over a couple feet. A summary of the footing design criteria is presented in Table 3.

Table 3: Footing Design Criteria Summary

Footing Design Criteria Recommendations Notes

Perimeter Strip Footings Maximum Allowable

Bearing Pressure 16 inches minimum width, 36 inches minimum below grade

Static Loads (Dead & Normal Live):

4,000 psf

Transient Loads (Wind & Seismic):

5,300 psf

Interior Column Footings Maximum Allowable

Bearing Pressure Minimum width 18 inches square, 18 inches minimum below grade unless constrained by slab

The resultant load is assumed to be in the middle 1/3 of the footing

Static Loads (Dead & Normal Live):

4,000 psf

Transient Loads (Wind & Seismic):

5,300 psf

Exterior Cold Footings Maximum Allowable

Bearing Pressure Minimum width 18 inches square, 72 inches below grade

The resultant load is assumed to be in the middle 1/3 of the footing

Static Loads (Dead & Normal Live):

4,000 psf

Transient Loads (Wind & Seismic):

5,300 psf

Maximum Settlement Estimate

Total (in) Differential (in)

1 inch 0.5 inch

Subgrade Preparation and Structural Fill

Compact structural fill to 95% modified Proctor

Remove existing fill and replace with structural fill

Uplift Resistance. Uplift of shallow foundations due to wind and seismic events are resisted by the weight of the foundation and soil above the footing. Soil resistance in the shape of a truncated pyramid above the foundation should be included in design. The pyramid edges are defined by straight lines extending from the top of the footing on either side at a 2V:1H (vertical:horizontal) slope.

Floor Slab. If an interior floor slab is placed in the basement or on the ground level, it can be supported directly on native dense sand and gravel or properly compacted structural fill.

Foundation drains are recommended if the basement is expanded, interior or exterior to protect the basement space from water infiltration during spring runoff and snow melt. If moisture sensitive flooring is anticipated, a vapor retarder or barrier should be placed directly beneath the floor slab using design guidelines presented in ACI 302.1R-15 (ACI 2015).

6.2 Earthwork

Excavation. Any frozen or otherwise unsuitable soil, such as debris or organics, must be removed from beneath the building and replaced with structural fill or flowable fill. Soils that are disturbed, pumped, or rutted by construction activity should be redensified, if possible, or completely removed and replaced with structural fill or flowable fill.

Frozen Soils. Do not place fill, construct foundations, slab-on-grade, or concrete flatwork over frozen soils. Do not fill or backfill with frozen soils.

Structural Fill. Structural fill is defined as load-bearing fill placed under footings, building foundations, structural slabs or concrete flatwork. All structural fill should consist of non-frost susceptible (NFS) or possibly frost susceptible (PFS) gravel and contain no lumps, frozen material, organic matter, or other deleterious matter. Structural fill shall meet the following gradation requirements:

Sieve Size Percent Finer 3” 100*

1-1/2” 70-100 3/4” 30-100 ½” 25-100

No. 4 20-49 No. 40 0-25

No. 200 0-6 0.02mm 0-3

* The fill may contain up to 10 percent cobbles.

The upper 6 inches of structural fill below spread footings, grade beams, and slabs should not contain gravel larger than 1 inches to facilitate fine grading.

Other fill material, which does not meet this gradation requirement, may be acceptable for use.

Onsite sand and gravel are suitable for use in interior, heated spaces; however, the gradation of such material should be evaluated by the project geotechnical engineer prior to its use.

Limits of Fill and Backfill. Structural fill and backfill should extend laterally from the edge of footings and slabs-on-grade one-foot for each foot of fill beneath the footing or slab.

Geotextile. A separation geotextile for the foundation or interior concrete slab-on-grade is not anticipated for this project.

Utility Trench Backfill. A suitable granular bedding material meeting the gradation requirements for structural fill or the manufacturer’s recommended gradation should be placed and compacted to a depth of at least six inches below all utility lines. This bedding material should extend six inches above the top of pipe and should be compacted to 95 percent of the maximum dry density as determined by modified Proctor, ASTM D1557. The remainder of the trench should be backfilled with classified material. This material should be compacted in lifts not exceeding one foot in thickness to 95 percent of the maximum dry density as determined by modified Proctor, ASTM D1557.Fill Placement. Structural fill should be placed and compacted in lifts not exceeding

12 inches in loose thickness if a large vibratory compactor is used, or not exceeding 6 inches in loose thickness if a hand-operated compactor is used. Each lift of structural fill should be compacted throughout its entire depth to a density of at least 95 percent of the maximum dry density as determined by modified Proctor, ASTM D1557. All excavations should be completely dewatered before placement of structural fill.

Fill Testing. Frequent, in-place density tests should be performed in each lift of fill to verify that the fill has been properly compacted prior to placing subsequent lifts. The number of tests performed in each lift should be commensurate with the size of the area worked by the contractor, the variability of the soil types used as fill, and the amount of time an inspector spends on site observing the work. At a minimum, we recommend the following inspection and testing program:

Full-time inspection of excavation and backfill operations, One in-place density test per 5,000 square feet, per lift, within the building footprint, One in-place density test per 100 lineal feet at the bottom of continuous spread footings, One in-place density test at the bottom of every other isolated rectangular spread footing, One in-place density test per 100 lineal feet of utility trench, every lift, and

One in-place density test per 5,000 square feet of pavement, curb, and sidewalk, per lift.

6.3 Dewatering and Drainage

It is important that all water be removed from excavations until they are properly backfilled. It is the contractor's responsibility to determine the appropriate dewatering techniques for the construction methods chosen and for the soil and water conditions encountered. Expect significant volumes of water and difficulty controlling water infiltration during spring runoff and snow melt.

Existing footing drains are present around the perimeter of the current crawlspace and basement.

These drains will need to be retained in place and if they are damaged during foundation work, they will need to be repaired or replaced. In addition, if the basement and crawlspace area is expanded, new footing drains will need to be installed along the basement footing wall.

Conventional, geotextile-wrapped drains are suitable for interior or exterior use. Geocomposite drains or drain board may be more practical to use during the footing improvements or if constructing a new basement wall. A sump should be anticipated unless the foundation drains can be tied into the existing sewer line.

6.4 Seasonal Frost Protection

The ground floor of the structure must remain uninsulated and/or the basement and crawlspace areas must be heated to allow heat to escape into the foundation soils. In areas cleared of snow, we recommend installing a 2-inch-thick layer of non-water absorbing, closed-cell, 60 psi, extruded-polystyrene insulation horizontally from the outboard face of the foundation walls 4 feet beyond the edge of the footing. If insulation is incorporated in vehicle traffic areas, the depth must be approximately 18 inches. Below sidewalks of concrete slabs, it may be placed just below the slab or the leveling course. BERG2 analysis indicates frost depth will be less than 2 feet with insulation which will protect the bottom of the footing from freezing. To reduce differential movement between transitions from uninsulated to insulated particularly on walkways, the insulation should be tapered to reduce thickness over 24 inches of its width.

The foundation design recommendations are predicated on the foundation soils in the heated portion of the building remaining thawed throughout the construction period and over the life of the structure. The recommendations above accomplish this with heat from the building’s permanent heating system. If the building is not enclosed and its permanent heating system is not operative prior to the advent of freezing weather, other methods should be employed to prevent freezing of the foundation soils and the structural fill within the building area. The effectiveness of any construction frost protection scheme should be monitored closely.

6.5 Earth Pressures

Movement is needed to develop the full active or passive earth pressure states. The following sketch shows the general relationship between the earth pressure coefficients and wall movement.

Walls with level, sand/gravel backfill should be designed for the following unfactored equivalent fluid soil pressures:

Active Case: Cantilevered Walls

35 pcf - above the groundwater table 80 pcf - below the groundwater table (0.002 H minimum wall deflection away from the backfill, where H - the height of the soil above the base of the wall)

At Rest Case: Basement Walls or Walls Restrained from Movement at the Top

60 pcf - above the groundwater table 95 pcf - below the groundwater table (no wall deflection)

Passive Case: Walls Moving into the Soil

440 pcf - above the groundwater table 300 pcf - below the groundwater table (.01 H minimum wall deflection toward the backfill)

Coefficient of friction between formed or precast concrete and structural fill = 0.30. The coefficient of friction for concrete cast on native sand and gravel = 0.50.

Note: Drainage should always be provided behind retaining structures. A typical drainage system would consist of clean, free-draining gravel (protected by a geotextile) draining to a perforated subdrain and/or weep holes.

The drainage system should be designed by a qualified engineer and reviewed by the project geotechnical engineer. If drainage is not provided, then the maximum possible hydrostatic pressure against the wall should be included in the structural design of the wall.

2.0

1.0

3.0

Kp

Ko

Ka

Into Soil MassAway from Soil Mass

Tilt or Movement of Wall

La te ra l E ar th

P re ss ur e C oe ff ic ie nt s

It is important to the performance of the planned building that any unsuitable soils are removed where specified, that structural fill consists of proper materials and is adequately compacted, and the existing footings are not undermined during excavation of the existing fill. It is recommended that all excavation and backfill operations be observed by qualified inspection/testing personnel under the supervision of a geotechnical engineer. Frequent in-place density tests should be performed in each lift of the structural fill to verify that minimum fill densities are being attained.

The inspection/testing personnel should be employed by the owner or owner’s representative, not by the contractor, to avoid any inherent conflict of interest and to better ensure that the required level of quality assurance is achieved.

7.0 LIMITATIONS

This report has been prepared for the use of RIM Architects and the design team in design of the

Steel Visitor Center Improvements. Changes to the design, layout, or location of the facilities should be provided to the project geotechnical engineer for review. Significant changes may alter the conclusions and recommendations presented in this report.

Ground conditions between borings may be different than inferred and changes may occur over time. Without additional subsurface exploration, variations in the ground conditions may be encountered during construction. It is important to communicate unanticipated soil conditions to the project geotechnical engineer to evaluate if the conditions may influence the conclusions and recommendations. No warranty is expressed or implied by this report or the recommendations.

The geotechnical field program and recommendations followed the standard of care expected of professionals performing similar work on federal projects.

8.0 REFERENCES

ACI Committee 302 (2015). 302.1R-15 Guide to Concrete Floor and Slab Construction.

Farmington Hills, Michigan: American Concrete Institute, 76p.

Bacon, C.R. and Wright, H.M. (2017). Geologic Field-Trip Guide to Mount Mazama and Crater

Lake Calder, Oregon. USGS Scientific Investigations Report 2017-5022-J1, 47p.

Bacon, C.R., Ramsey, D.W. and Dutton, D.R. (2008). Geologic Map of Mount Mazama and Crater

Lake Caldera, Including the Database for the Geologic Map of Mount Mazama and Crater

Lake, Oregon. USGS Scientific Investigation Map SIM-2832, scale 1:24,000 and accompanying report.

NPS (2013). Crater Lake National Park Geologic Resources Inventory Report. Natural Resource

Report NPS/NRSS/GRD/NRR-2013/719. National Park Service Geologic Resources

Division. 70p., map plates.

Scoping Report (2013): Leavengood Architects, Inc., CT Engineering, Inc., Wood Harbinger, Inc., Matson Carlson Cost Estimating. 100% Scoping Services Report: Rehabilitation of Steel

Visitor Center. NPS-provided document, 217p., dated March 8, 2013.

USGS (2018). Volcano Hazards Program, online volcanic threat inventory, www.volcanoes.usgs.

gov/volcanoes/crater_lake. Accessed September 20, 2018.

USGS (2016). U.S. Seismic Design Maps. Retrieved February 24, 2016, from USGS Seismic

Design Maps Application, http://earthquake.usgs.gov/designmaps/us/application.php.

USGS (1997). Volcano and Earthquake Hazards in the Crater Lake Region, Oregon. USGS

Open-File Report 97-487, 32p, map plates.

APPENDIX A

Test Boring Location Map

VICINITY MAP

Steel Visitor Center Crater Lake National Park Klamath County, Oregon

1122.62731.01

Map source: Google Earth

LJB

LJB

9/12/18 lbrandt Oval lbrandt Line lbrandt Text Box Project Site

SITE PLAN

Map source: Google Earth

1122.62731.01

BH#1 & BH#2 - Borehole Locations

Steel Visitor Center Crater Lake National Park Klamath County, Oregon

LJB

LJB

9/12/18 lbrandt Oval lbrandt Oval lbrandt Text Box

BH#2

lbrandt Text Box

BH#1

lbrandt Text Box Steel Visitor Center

APPENDIX B

Test Boring Logs and Descriptive Guide

MA

MA

MA

MA

58*

70*

29*

F3

F1

F4

F3

SM

GP

SM

SM

SILTY SAND WITH GRAVEL, reddish brown, about 40% gravel, 15% silt, gravel subrounded to 2", medium sand, moist, medium dense

POORLY GRADED GRAVEL WITH SAND, reddish brown to dark brown, about 35-40% sand, 10% silt, gravel subrounded to 2", medium sand, moist, dense

SILTY SAND WITH GRAVEL, dark brown to grayish brown, about 30% gravel, 30% silt, nonplastic, gravel subrounded to 1.5", medium sand, moist, dense to very dense cobbles

SILTY SAND, reddish brown to brown, about 10% gravel, 15-20% silt, nonplastic, gravel subrounded to 1.5", medium sand, moist, medium dense

5.5

14.0

28.0

S am p le

N o

DEPTH

D E

P T

H

F E

E T

F ro st C la ss

M o is tu re C o n te n t

B lo w s

/ F o o t

TEST BORING 1

FIGURE B-1

W.O. 1122.62731.01

LOG OF TEST BORING 1

S am p le

T yp e

S o il G ra p h

DRILLING CO.: HazTech Drilling, Inc.

EQUIPMENT: CME-85 Truck

OPERATOR: Aaron Delvalle

METHOD: 8 in. OD hollow-stem auger

LOGGED BY: Laurie Brandt, CPG

TEST BORING COMPLETED: 9-12-18

CLIENT: National Park Service

F ro st D ep th

PROJECT: CLNP Steel Visitor Center

S o il C la ss

O th er T es ts

LOCATION: SEE TEST BORING LOCATION MAP

ELEVATION:

SURFACE: Grass

KEY

MA = Mechanical Analysis TD = Total Depth

= Grab Sample = SPT Sample = Shelby Tube - pushed = Direct Push Sample = 2.5" I.D. Spoon Sample 140# weight, 30" fall

LO

G

O F

E X

P

LO

R A

T

IO

N

.G P

J B

LA

N

K 2.

G D

T

0/

2/

*Uncorrected for large sample size

MA

MA

24*

22*

24*

22*

F3

F4

SM

TD=51.5'

Groundwater encountered at 45.5' while drilling

TEST BORING COMPLETED ON 9-12-18

TEST BORING BACKFILLED WITH BENTONITE AND

CUTTINGS

51.5

S am p le

N o

DEPTH

D E

P T

H

F E

E T

F ro st C la ss

M o is tu re C o n te n t

B lo w s

/ F o o t

TEST BORING 1 (Continued)

FIGURE B-1

W.O. 1122.62731.01

LOG OF TEST BORING 1

S am p le

T yp e

S o il G ra p h

LOGGED BY: Laurie Brandt, CPG

DRILLING CO.: HazTech Drilling, Inc.

EQUIPMENT: CME-85 Truck

OPERATOR: Aaron Delvalle

METHOD: 8 in. OD hollow-stem auger TEST BORING COMPLETED: 9-12-18

CLIENT: National Park Service

F ro st D ep th

PROJECT: CLNP Steel Visitor Center

S o il C la ss

O th er T es ts

LOCATION: SEE TEST BORING LOCATION MAP

ELEVATION:

SURFACE: Grass

KEY

MA = Mechanical Analysis TD = Total Depth

= Grab Sample = SPT Sample = Shelby Tube - pushed = Direct Push Sample = 2.5" I.D. Spoon Sample 140# weight, 30" fall

LO

G

O F

E X

P

LO

R A

T

IO

N

.G P

J B

LA

N

K 2.

G D

T

0/

2/

*Uncorrected for large sampler size

MA

MA

50/2

115/8*

S1

F4

F4

GP

SM

SM

C1

POORLY GRADED GRAVEL WITH SAND, reddish brown, about 45% sand, 5% silt, gravel subrounded to 1.5", medium sand, moist, very dense, cobbles and boulders

SILTY SAND WITH GRAVEL, reddish brown, about 30% gravel, 15% silt, nonplastic, gravel subrounded to 1.5", medium sand, moist, dense to very dense boulder cored from 22.5' to 26.5'

8.5

30.0

S am p le

N o

DEPTH

D E

P T

H

F E

E T

F ro st C la ss

M o is tu re C o n te n t

B lo w s

/ F o o t

TEST BORING 2

FIGURE B-2

W.O. 1122.62731.01

LOG OF TEST BORING 2

S am p le

T yp e

S o il G ra p h

LOGGED BY: Laurie Brandt, CPG

DRILLING CO.: HazTech Drilling, Inc.

EQUIPMENT: CME-85 Truck

OPERATOR: Aaron Delvalle

METHOD: 8 in. OD hollow-stem auger TEST BORING COMPLETED: 9-12-18

CLIENT: National Park Service

F ro st D ep th

PROJECT: CLNP Steel Visitor Center

S o il C la ss

O th er T es ts

LOCATION: SEE TEST BORING LOCATION MAP

ELEVATION:

SURFACE: Grass

KEY

MA = Mechanical Analysis TD = Total Depth

= Grab Sample = SPT Sample = Shelby Tube - pushed = Direct Push Sample = 2.5" I.D. Spoon Sample 140# weight, 30" fall

LO

G

O F

E X

P

LO

R A

T

IO

N

.G P

J B

LA

N

K 2.

G D

T

0/

2/

MA

MA

MA

MA

F4

SM

TD=52.0'

C2

SILTY SAND, brown, about 5-10% gravel, 15-25% silt, nonplastic, gravel subrounded to 3/4", coarse sand, moist, loose to medium dense

TEST BORING COMPLETED ON 9-12-18

NO GROUNDWATER OBSERVED DUE TO CORING WITH

WATER

TEST BORING BACKFILLED WITH BENTONITE AND

CUTTINGS

52.0

S am p le

N o

DEPTH

D E

P T

H

F E

E T

F ro st C la ss

M o is tu re C o n te n t

B lo w s

/ F o o t

TEST BORING 2 (Continued)

FIGURE B-2

W.O. 1122.62731.01

LOG OF TEST BORING 2

S am p le

T yp e

S o il G ra p h

LOGGED BY: Laurie Brandt, CPG

DRILLING CO.: HazTech Drilling, Inc.

EQUIPMENT: CME-85 Truck

OPERATOR: Aaron Delvalle

METHOD: 8 in. OD hollow-stem auger TEST BORING COMPLETED: 9-12-18

CLIENT: National Park Service

F ro st D ep th

PROJECT: CLNP Steel Visitor Center

S o il C la ss

O th er T es ts

LOCATION: SEE TEST BORING LOCATION MAP

ELEVATION:

SURFACE: Grass

KEY

MA = Mechanical Analysis TD = Total Depth

= Grab Sample = SPT Sample = Shelby Tube - pushed = Direct Push Sample = 2.5" I.D. Spoon Sample 140# weight, 30" fall

LO

G

O F

E X

P

LO

R A

T

IO

N

.G P

J B

LA

N

K 2.

G D

T

0/

2/

TEST BORING LOG – DESCRIPTIVE GUIDE

Soil Descriptions – The soil classified visually in the field based on drill action, auger cuttings, and sample information. The recovered soil samples are classified visually again in the laboratory. The soil description on the on the boring log is based on an interpretation of the field and laboratory visual classifications, along with the results of the laboratory testing which may have been performed.

The soil classification is based on ASTM Designation D2487 “Standard Test method for Classification of Soils for Engineering Purposes” and ASTM D 2488 “Standard Practice for Description and Identification of Soils (Visual – Manual Procedure)”. The soil frost classification is based on the system developed by the U.S. Army Corps of Engineers and is performed in accordance with the Departments of the Army and Air Force Publication TM 5-822-5 “Pavement Design for Roads, Streets, Walks, and Open Storage Areas”. Outlines of these classification procedures are presented on the following pages.

The soil color is the subjective interpretation of the individual logging the test boring.

Plasticity Indices - The plasticity of the minus No. 40 fraction of the soil is described and the fine-grained soils are identified from manual tests using the following tables as a guide:

Soil Symbol Dry Strength Dilatancy Toughness ML none to low slow to rapid low or thread cannot be formed CL medium to high none to slow medium MH low to medium none to slow low to medium CH high to very high none high

Plasticity Description

Criteria

Non Plastic A 1/8” (3.2mm) thread cannot be rolled at any water content

Low A thread can barely be rolled and the lump cannot be formed when drier than the plastic limit

Medium The thread is easy to roll and not much time is required to reach the plastic limit. The thread cannot be rerolled after reaching the plastic limit.