MJ1709.04_Waterfall Overlooks Design-Technical Specifications.pdf

United States Department of Agriculture

Forest Service

Ottawa National Forest Black River Harbor Recreational Area, MI

Waterfall Overlook Platforms and Access Stairs

F-0080

Technical Specifications

May 1, 2025

SEALS PAGE

MJ Project No. 1709.04

SEALS PAGE

Project Title: BRHRA Waterfall Overlooks Design

Project Location: Ironwood Center Township, MI

Project Number: MJ 1709.04

Contract Number: 1256A120D0016/12445524F0080

SEALS AND SIGNATURES OF DESIGN PROFESSIONALS OF RECORD

ENGINEER’S SEAL

Registration Expires 10/31/2026

000110 Table of Contents

SECTION 000110

TABLE OF CONTENTS

APPENDICES

APPENDIX A - GEOTECHNICAL REPORT

SPECIFICATIONS

DIVISION 01 -- GENERAL REQUIREMENTS

A. 015713 - Temporary Erosion and Sediment Control

DIVISION 02 -- EXISTING CONDITIONS

A. 024100 - Demolition

DIVISION 03 -- CONCRETE

A. 031000 - Concrete Forming and Accessories B. 032000 - Concrete Reinforcing C. 033000 - Cast-in-Place Concrete

DIVISION 05 -- METALS

A. 051200 - Structural Steel Framing

DIVISION 06 -- WOOD, PLASTICS, AND COMPOSITES

A. 060573 - Wood Treatment B. 061000 - Rough Carpentry

DIVISION 31 -- EARTHWORK

A. 311000 - Site Clearing B. 312200 - Grading C. 312316 - Excavation D. 312323 - Fill E. 316615 - Helical Foundation Piles

DIVISION 32 -- EXTERIOR IMPROVEMENTS

A. 329219 - Seeding

APPENDIX A

GEOTECHNICAL REPORT

January 21, 2025 Project No. 241747

MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C.

21 Corporate Drive Clifton Park, New York 12065

Attention: Matt Fueston, P.E.

Project Manager

Reference: Report of Geotechnical Investigation BRHRA Waterfall Overlook Platforms and Access Stairs – Phase 2 Ironwood, Michigan

Dear Mr. Fueston:

MATERIALS TESTING CONSULTANTS, INC. has completed a geotechnical investigation for the above-referenced project. The findings of the study along with recommendations for the design of foundations and earth-related structures are presented in the attached report.

We appreciate this opportunity to provide foundation engineering services and express our interest in providing continuing services in the areas of subgrade verification, special inspections and quality assurance testing on various construction materials. Please contact our office should you have any questions or require further assistance.

Sincerely, MATERIALS TESTING CONSULTANTS, INC.

Jacob M. Siegrist, P.E.

Project Manager

Todd D. Munger, P.E.

Vice President, Senior Project Manager att: Report

GEOTECHNICAL REPORT

BRHRA WATERFALL OVERLOOK PLATFORM AND ACCESS STAIRS – PHASE 2

IRONWOOD, MICHIGAN

Prepared For:

MJ ENGINEERING, ARCHITECTURE, LANDSCAPE ARCHITECTURE, & LAND SURVERYING, P.C.

CLIFTON PARK, NEW YORK

Prepared By:

MATERIALS TESTING CONSULTANTS, INC.

JANUARY 2025

MTC Project No. 241747

TABLE OF CONTENTS

Section Page

1.0 INTRODUCTION 1

2.0 DESIGN CONSIDERATIONS 2

2.1 Available Information 2

2.2 Project Description 2

3.0 INVESTIGATION METHODOLOGY 3

3.1 Field Investigation 3

3.2 Laboratory 5

4.0 INVESTIGATION RESULTS 5

4.1 Regional Geology 5

4.2 Site Conditions 6

4.3 Subsurface conditions 9

5.0 CONCLUSIONS AND RECOMMENDATIONS 11

5.1 Slope Stability Evaluation 12

5.2 Foundations 14

5.3 Subgrade Preparation 17

5.4 Groundwater 19

5.5 Slopes and Temporary Excavations 19

5.6 Below-Grade Walls 20

5.7 MBC Seismic Considerations 20

6.0 CLOSURE 21

FIGURE BORING LOCATION PLANS

APPENDIX LIMITATIONS

TEST DRILLING AND SAMPLING PROCEDURES

BORING LOG TERMINOLOGY AND CLASSIFICATION OUTLINE

BORING LOGS

LABORATORY SUMMARY TABLE

MDOT GRADATION SUMMARY

REPORT OF GEOTECHNICAL INVESTIGATION

BRHRA WATERFALL OVERLOOK PLATFORM AND ACCESS STAIRS – PHASE 2

1.0 INTRODUCTION

MATERIALS TESTING CONSULTANTS, INC. (MTC) has completed a geotechnical investigation for the Black River Harbor Recreation Area (BRHRA) Overlook Platforms and Access Stairs Phase 2 project, located in Ironwood, Michigan. This work has been performed as described in our proposal, number 18509 and dated August 2, 2024 with scope revisions noted in our email dated November 5, 2024. Authorization to proceed was received from Mr. Matt Fueston, P.E.

in an email dated October 1, 2024. The scope of this study was described in an RFP email and statement of work document dated April 12, 2024.

The scope of this study in general includes the following:

• performance of a field investigation including soil test borings and field engineering reconnaissance;

• review of recovered samples by one of our engineers and assignment of technical soil classifications;

• performance of laboratory testing on selected soil samples;

• engineering evaluation of encountered conditions with respect to the proposed construction; and

• preparation of this report.

Presented herein are descriptions of our understanding of the design considerations, the investigation program, encountered conditions and engineering recommendations. The Appendix contains the report limitations, boring log terminology, soil classification chart, boring logs and laboratory test data.

Report of Geotechnical Investigation

2.0 DESIGN CONSIDERATIONS

2.1 Available Information

We have been provided the following documents and information for use in this investigation:

• A scope of work plan set for the proposed improvements titled “Waterfall Overlook

Platform & Access Stairs” at the Black River Harbor Recreation Area (BRHRA) prepared by MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C. dated December 13, 2024, which detailed the updated proposed improvements and existing site grades.

• An AutoCAD drawing for the proposed waterfall outlook improvements detailing existing site grades prepared by MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C. and received via email on November 13, 2024.

• A site survey and conceptual design plans for the BRHRA Waterfall Overlook Platform & Access Stairs project prepared by MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C. and dated December 29, 2023, included with the geotechnical RFP which detailed the original project scope and site grading information.

• Email correspondence, meeting attendance, and telephone conversations with Mr. Matt Fueston, P.E., Mr. Michael Wiley, P.E., and Mr. Christopher Armstrong of MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C., and Mr. Eric Johnson, Ms.

Tiffany Atchison, Mr. Kenneth Keeley, Mr. Trevor Hahka, Ms. Megan Impson, Mr. Joseph Stieber, Mr. Jesse Phillips, Ms. Sydney Kurtic, Ms. Spring Rosales, Mr. Bradley Dalbec, and Mr. Mark Surprenant of the United States Forest Service regarding the project scope, schedule of the field investigation, type of construction, design loads and elevations.

2.2 Project Description

The proposed construction at Sandstone Falls and Rainbow Falls will be located in plan as shown on the attached Boring Location Plans, Figure Nos. 1 through 3. The site is located at the Black River Harbor Recreation Area in Ironwood, Michigan.

Sandstone Falls

The construction will include the replacement of approximately 200 linear feet of existing timber steps with an elevated wood stair structure supported on either helical piers or concrete piers. The elevated stair structure will be approximately 5 ft wide with a maximum support spacing of 20 ft with the alignment to mirror the existing staircase. We have considered maximum axial and lateral loads of 6,000 lbs and 450 lbs per pier, respectively.

Rainbow Falls

The construction will include localized replacements of pier foundations along the existing, approximately 320 ft long, stair alignment in addition to the construction of two new viewing platforms. The new viewing platforms will be approximately 50 square feet and will require two to four new pier foundations. We have considered maximum axial and lateral loads of 6,000 lbs and 450 lbs per pier, respectively.

We should be informed of any changes between the actual design conditions and those described herein as this information may affect our recommendations.

3.0 INVESTIGATION METHODOLOGY

3.1 Field Investigation

Subsurface conditions were investigated by two conventional soil test borings (Borings B-1 and B-2) and thirteen supplemental hand auger borings (Borings HA-1 through HA-13A). Two additional hand auger borings (Borings HA-12A and HA-13A) were added due to shallow hand auger refusal to confirm refusal. Conventional soil boring depths ranged from 54.5 to 80 ft below the existing ground surface where auger refusal was encountered on very dense sand or silt. Hand auger boring depths ranged from 0.9 to 10 ft below the existing ground surface.

Boring locations are shown on the attached plans, Figure Nos. 1 to 3.

One of our engineers staked the approximate boring locations in the field. Boring elevations were approximated by interpolation between plan contours on the provided grading plans.

The elevations used in this report are given in feet and are based on NAVD88 datum. If more precise location and elevation data are desired, a registered professional land surveyor should be retained to locate the borings and determine their ground elevations.

The drilling was performed using conventional hollow-stem auger or hand auger methods to advance the boreholes. The boreholes were backfilled to the original ground surface after drilling completion.

For conventional soil test borings, soil samples were recovered at regular intervals by means of the Standard Penetration Test (SPT), ASTM D1586. The SPT test involves the use of a 140-lb hammer with a 30-inch drop to drive a standard 2.0-inch O.D. split spoon sampler. The number of hammer blows required to drive the sampler 12 inches, after seating 6 inches, is termed the soil N-value and provides an indication of the soil's relative density and strength parameters at the sample location. SPT blow counts in 6-inch increments are recorded on the boring logs. The drill rig was equipped with an automatic hammer system which delivers a more consistent driving energy to the sampler compared to the rope and cathead system.

Where cohesive soil was encountered, relatively undisturbed tube samples were attempted using the Shelby style adaptor and procedures described in ASTM D1587; however, no samples were recovered. For hand auger borings, dynamic cone penetrometer testing was completed at regular intervals according to ASTM STP399 where granular soil was encountered.

Recovered samples were sealed, labeled and transported to our laboratory. All soil samples will be discarded after sixty days unless a longer hold time is specifically requested.

The recovered soil samples were reviewed by an engineer and technically classified according to the methods of ASTM D2488 "Standard Practice for Description and Identification of Soils (Visual-Manual Procedure)". Estimates of the unconfined compressive strength of the cohesive samples were made using a calibrated penetrometer. A copy of the test boring logs along with a description of the terminology used on the logs and a chart of the ASTM D2488 group symbol names are provided in the Appendix.

Borings were drilled and other sampling was conducted solely to obtain indications of subsurface conditions as part of a geotechnical exploration program. No services were performed to evaluate subsurface environmental conditions.

3.2 Laboratory

Selected samples were subjected to various laboratory tests, including:

• ASTM D2216 "Test Methods for Laboratory Determination of Water (Moisture) Content of

Soil and Rock by Mass”

• ASTM D4318 "Test Method for Liquid Limit, Plastic Limit and Plasticity Index of Soils"

The samples subjected to plasticity testing were reclassified according to ASTM D2487 procedures "Standard Test Method for Classifications of Soils for Engineering Purposes". The ASTM D2487 and D2488 classifications are included on the boring logs.

Results of the laboratory tests have been summarized in a table provided in the Appendix.

4.0 INVESTIGATION RESULTS

4.1 Regional Geology

Based on water well records from the Michigan Department of Public Health, soil conditions in this geologic region typically consist of clayey sand, gravel and boulders consistent with those encountered in this investigation. Bedrock is expected to vary considerably with elevations ranging from 650 to 750 ft. Overburden thicknesses generally decreased as ground surface elevation decreased especially adjacent to the Black River and Lake Superior.

The geologic formations in this area were formed during the last glacial retreat with glaciers carving out the ravines and slopes currently present, which have been modified through natural erosion processes over the last approximately 15,000 years.

4.2 Site Conditions

At the time of our field work, the area of investigation was covered with heavy mature trees and both viewing areas at Sandstone and Rainbow Falls had considerable slopes down to the Black River. Slope angles at both falls ranged from approximately 1V:3H to 1V:2H along the existing structures and proposed improvement areas. Overburden soil appeared to have been scoured with bedrock visible within the river channel.

We understand the existing structures were constructed approximately 50 years ago with timber steps placed on grade anchored at corners with driven rebar stakes and elevated stairs supported on concrete piers. No obvious evidence for slope movement, beyond surficial erosion, was observed during our reconnaissance efforts with no reports of slope movement provided by the United States Forest Service since original construction of the structures with mature trees present and generally vertical indicating that the slope mass has generally remained stable for at least the last 50 to 100 years.

Sandstone Falls

The site, in general, sloped downward toward the Black River with elevations ranging from 880 at the slope crest to 740 near the river.

The existing on grade timber step structure showed signs of surficial movement and erosion with no water management features observed along its length. Several timbers steps were not level and appeared to have shifted laterally. Scoured channels adjacent to the steps on the order of 1 ft in depth were observed where surface water has been allowed to flow freely down the slope towards the river. No indications of global slope instability such as tension cracking or falling trees were observed with structure movement anticipated to be primarily a result of surface erosion over many years resulting in marginal support and associated movement.

Existing Staircase Near Boring HA-2

Existing Staircase Near Boring HA-4

Rainbow Falls

The site, similar to the Sandstone Falls, sloped downward toward the Black River with elevations ranging from 760 at the slope crest to 610 near the river.

The existing staircase showed signs of erosion and potential frost heave with frequent unlevel steps and exposed pier footings observed. Up to approximately 12 inches of exposed pier footing was observed at multiple locations along the staircase and scour channels from uncontrolled surface water runoff near existing pier foundations were noted. Existing pier foundations on the order of 2 to 3 ft in depth were generally observed with diameters on the order of 12 inches. No indications of global slope instability such as tension cracking or falling trees were observed.

Staircase Structure Near Boring HA-12

Lateral movement of the staircase superstructure was observed near Boring HA-10 which appeared to be secondary to a large tree pushing against the staircase structure.

Lateral Displacement of the Staircase Near Boring HA-10

4.3 Subsurface Conditions

The investigation, in general, encountered a mixture of granular and cohesive overburden soils with bedrock observed or encountered at depths of approximately 100 to 150 ft below the slope crest.

The relative density of granular soil is based on recorded SPT N-values while the consistency of cohesive soil is based on estimates of the unconfined compressive strength obtained with a calibrated penetrometer. Static groundwater is expected near bedrock and Black River water levels with perched groundwater or seepage present at higher elevations. Groundwater levels will fluctuate due to seasonal variations such as precipitation, snowmelt, nearby Black River and other factors that may not be evident at the time of measurement. Groundwater levels may be different at the time of construction. This section provides a generalized description of encountered subsurface conditions. The boring logs provided in the Appendix should be reviewed for more detailed subsurface information. Some variation between boring locations should be expected.

Sandstone Falls

The borings encountered 3 to 13 inches of topsoil overlying very loose to medium dense red brown clayey or silty sand at the surface to depths ranging from 3 to 8.7 ft underlain by stiff to hard red brown lean clay to a depth of 42 ft above dense to very dense red brown sand with silt, silty sand, or sandy silt to a depth of 80 ft where auger refusal was observed. A layer of hard red brown lean clay was encountered between 69 and 72 ft.

Groundwater was encountered during the drilling activities at depths ranging from 2.9 to 67 ft (elevations 771.6 to 812.5) with large variability likely due to frequent cohesive soils perching groundwater.

Rainbow Falls

The borings encountered 3 to 9 inches of topsoil overlying loose to medium dense red brown poorly graded sand, silty sand, poorly graded sand with silt, or silt to a depth of 19.5 ft underlain by stiff red brown lean clay above dense to very dense red brown silt to the explored depth of 54.5 ft where auger refusal was encountered.

Groundwater was encountered during the drilling activities at depths ranging from 7.5 to 13 ft (elevations 675.5 to 748) with large variability likely due to frequent cohesive soils perching groundwater.

5.0 CONCLUSIONS AND RECOMMENDATIONS

The natural slope upon which the existing and proposed structures are or will be present is currently marginally stable, as confirmed through our slope stability evaluation summarized within Section 5.1. The slope is expected to have been formed through glacial processes as well as natural erosional processes associated with the Black River and surface runoff during precipitation events and snow melt over thousands of years. No obvious evidence for global slope instability is currently present and the age of the existing structures and vegetation on the slope surface indicate the slope has generally remained in its current geometry for at least 50 to 100 years.

Although stabilization of the slope to a defined factor of safety with respect to slope stability is possible, the scope and cost relative to the limits and slope geometry of such an approach is expected to be prohibitive to the project relative to reasonably acceptable performance of the existing structures to date and the anticipated risk to future users. In discussions with the design team, we understand the intent of the project will not be increasing existing slope stability but rather, to select foundation systems which are not expected to negatively affect slope stability while implementing surface erosion control and drainage measures to resist future slope loss associated with surface erosion. With the implementation of erosion control measures, acceptable construction practices, including foundations bearing below the regional frost penetration depth, and this general approach to slope stability, we anticipate future performance of the structures to be similar or better compared to past performance.

Presented herein are conclusions drawn from our slope stability evaluation and associated geotechnical recommendations for design and construction of the proposed improvements.

We would welcome the opportunity to review final construction documents to evaluate and confirm that our recommendations have been appropriately addressed.

5.1 Slope Stability Evaluation

Natural slopes commonly are found to possess relatively low factors of safety, typically near

1.0 or slightly above, with respect to global slope stability due to their deposition and geometry as well as prolonged erosion which acts to remove soil from the slope over time eventually leading to a critical state and subsequent slope mass movement. Intense or sustained rainfall or rapid snowmelt can also lead to slope instability through saturation (add driving forces), increase groundwater levels and increase seepage pressure within the slope mass. When forces acting to drive failure exceed resisting forces, slope instability (movement) may occur, potentially in the form of rotational or translational slides until a stable state is again achieved.

Providing adequate drainage of excess surface water and groundwater in addition to appropriate erosion control measures typically are found to be beneficial in reducing erosional forces acting on the slope as well as the destabilizing effect water may have on overall slope stability.

Slope stability evaluation requires the assignment of soil strength parameters, namely internal friction angle, cohesion and soil unit weight. Empirical soil strength parameters were utilized in conjunction with the existing slope geometry to create slope stability models using SLIDE2 software. Internal friction angles and drained shear strength parameters were estimated using empirical correlations. Stability was evaluated for the existing and proposed conditions with global stability safety factors predicted to range from 1.1 to 1.3 for both Sandstone and Rainbow Falls. Considering existing slope grades will remain unchanged with the use of isolated pier foundation elements supporting reconstructed structure, we anticipate the proposed construction will have a minimal negative impact on existing global slope stability, resulting in a slope stability condition similar to existing.

Section A-A Sandstone Falls

Section B-B Rainbow Falls

The appropriate collection and discharge of surface water and implementation of erosion control measures will be important to the long-term performance of the structures to minimize erosion which could act to both undermine foundation elements over time and destabilize the slope. Stormwater should be collected at the slope crest and along the slope surface adjacent to the structures to avoid allowing surface water to freely flow down the slope surface, appropriately discharging collected water at the toe of slope. Selection of erosion control measures are outside of our scope of work, however, may consist of native vegetation, erosion control blankets or similar systems designed to resist erosion.

5.2 Foundations

Due to the presence of existing slopes, challenging access conditions for construction equipment are expected. In the interest of minimizing access efforts while providing foundation elements capable of supporting the anticipated structure loading and driving structure loads sufficiently deep into the slope mass, two pier foundation systems are anticipated to be feasible, as described herein.

Concrete Piers

A concrete pier foundation system is expected to be feasible for support of the proposed structures. It is important that the recommendations of this report, in particular those pertaining to subgrade preparation, construction observation and testing, be implemented during design and construction.

The following parameters are recommended for concrete pier foundation design:

Table No. 5.2.1 – Concrete Pier Design Parameters

Bearing pressure for circular pier foundations, maximum net allowable, psf

Minimum diameter of circular pier foundations, inches 18 Minimum embedment depth for frost protection, inches 72 Maximum anticipated lateral deflection for foundations, inches ≤1/8 Maximum anticipated total foundation settlement, inches ≤1 Maximum anticipated differential foundations settlement, inches ≤1/2

Foundations are expected to bear on the hard lean clay or medium dense poorly graded sand as encountered in the borings or on approved engineered fill. Subgrade preparation recommendations are contained in the following section.

Foundation recommendations presented herein are based on a safety factor to resist bearing capacity failure of at least 3.0. A minimum embedment depth, beyond what is specified in the Michigan Building Code, for frost protection has been recommended to account for deep frost penetration as has been observed in neighboring towns in addition to any potential future erosion which may occur near the top of foundation elements.

Helical Piers

Supporting new structures on deep foundations such as helical piers are expected to be feasible and beneficial in that new structural loading will effectively be transferred below the surface of the slope, limiting negative impact to existing slope stability. The Structural Engineer should specify the helical piers as a performance-based design, completed by the Contractor, by supplying the maximum allowable helical pier c-c spacing, the structural loading criteria, and the allowable settlement criteria. The Contractor should be responsible for selecting, designing and installing the helical pier system.

A helical pier foundation system is a segmented deep foundation system consisting of steel bearing plates (helices) welded to a central steel shaft. The central steel shaft is typically manufactured in 5 to 10 ft lengths with a wide array of shapes and sizes. After the helices are welded onto the shaft sections at predetermined locations, the pier is “screwed” into the ground by applying a torque and adding steel extensions until the desired depth and torque are reached. Helical piers can be installed using relatively lightweight construction machinery, such as excavators outfitted with specialized drive-head attachments. When installing helical piers through soil, the design capacity of the pier foundation system is directly related to the structural strengths of the pier shaft, helices and bracket assembly. The ultimate capacity for each helical pier can be verified by monitoring the torque applied during installation and performing an empirical correlation to determine the theoretical bearing capacity at various depths.

The work should be performed by a Contractor with at least 5 years of experience installing similar foundation systems. The Structural Engineer should supply the Contractor with the design loads to facilitate the design of the helical pier elements. A minimum factor of safety of 2.0 should be applied by the Contractor to the design loads to determine the required ultimate capacity needed for each pier. The Contractor should evaluate lateral loading of the pier elements. Lateral loads on pier elements should be resisted by battered piers. The lead section should be installed so that all helices bear at least 6 ft below the ground surface achieving the minimum required torque over the last 3 ft of installation. A minimum separation in plan between adjacent helices of 3 ft or 2.5 times the helix diameter should be maintained.

We recommend that all helical pier materials are treated with hot dip galvanizing or equivalent for corrosion resistance. The Contractor’s installation equipment should be calibrated, and calibration charts should be submitted to the Engineer before the start of work equating installation torque or pressure to pier ultimate capacity (in kips). The Contractor’s submittal should indicate the proposed layout of the helical pier locations with ultimate bearing capacities, helical pier type, estimated length, typical pier-to-footing connection detail, and corrosion and buckling analyses. The submittal should be prepared by a Professional Engineer licensed in the State of Michigan and submitted at least two weeks before construction to the Structural Engineer for review. The Structural Engineer should determine the locations for helical pier installation. We remain available to review this submittal from a geotechnical perspective for conformance with the construction documents and recommendations contained within this report.

The following table summarizes the recommended helical pier design parameters:

Table No. 5.2.2 – Helical Pier Design Parameter Summary

Minimum factor of safety for allowable pier capacity 2.0 Minimum installation depth for all pier helices, feet 6 Minimum spacing between adjacent helices, feet 3 or 2.5 times helix diameter Maximum anticipated total foundation settlement, inches

<1

Maximum anticipated differential foundations settlement, inches

<1/2

Mechanism for resisting lateral loads Battered piles

5.3 Subgrade Preparation

Although not anticipated to be a significant project concern, considering the subsurface conditions encountered, it is possible that some form of subgrade improvement may be required over sections of the proposed staircase improvement areas to provide suitable foundation bearing conditions. Subgrade improvement may include, but not necessarily limited to, densification of existing soil in-place or excavation of all unsuitable material to an approved subgrade and replacement with engineered fill. If overexcavation is selected, it should encompass soil within the stress influence region of the foundation, defined as a region bordered by 2V:1H planes extending down and away from the bottom edge of the foundation to the approved bearing stratum.

The foundation subgrade should be inspected and tested by qualified geotechnical personnel.

As part of the inspection and testing, the subgrade at each individual bearing element should be verified to be consistent with the conditions encountered in this investigation and the indicated recommended allowable bearing pressures. This testing should include the verification of acceptable unconfined compressive strengths in cohesive soil and a dynamic cone penetrometer (ASTM STP 399) to verify minimum relative densities and equivalent N-values in granular soil. Care should be taken to maintain the natural moisture content of clayey subgrade soil which may become soft when saturated from rainfall, etc.

A minimum 6-inch base of MDOT 21AA dense graded aggregate should be placed below any concrete flatwork or timber steps supported on-grade. In addition to controlling erosional forces from runoff and enhancing long-term performance, the MDOT 21AA base could also serve as a haul road to access the proposed path with equipment and supplies. For additional erosion resistance, the MDOT 21AA dense graded aggregate should be completely wrapped with non-woven geotextile.

Engineered fill is approved on-site or imported soil placed in uniform layers and compacted to a minimum required density. Generally, on-site soil with group symbols of SP or SP-SM are expected to be suitable for engineered fill. Imported engineered fill should meet the requirements for MDOT Class II granular material. MDOT Class II soil or approved on-site soil meeting the requirements of SP or SP-SM should be used as backfill against foundations.

Gradation requirements for both MDOT Class II sand and MDOT 21AA dense graded aggregate have been summarized in the Appendix.

Granular engineered fill and backfill should be compacted to at least 95 percent of the soil's maximum dry density as determined by the Modified Proctor test (ASTM D1557). Vibratory compaction methods are typically found to be most effective in granular soils; however, relatively light equipment should be used adjacent to existing foundations to avoid overstressing the structures.

The fill should be placed and compacted in horizontal layers not exceeding 9 inches. Field density tests should be taken on each lift, as the fill is being placed, to verify compliance with compaction specifications.

If the earthwork takes place during winter months, fill must not be placed on frozen ground and fill with frozen conglomerations of soil must not be used.

Because the site has been previously developed, there may be buried items not encountered in our borings, such as a septic tank, well, or utility conduit, which may cause settlement problems. The contract documents should reflect that it is necessary to remove or relocate such structures and to fill the excavation with engineered fill.

5.4 Groundwater

Groundwater was generally encountered in the borings at elevations ranging from 771.6 to

812.5 ft at Sandstone Falls and from 675.5 to 748 ft at Rainbow Falls, close to the anticipated depth of excavation for foundation construction. Due to the partially cohesive soil profile, groundwater will likely be encountered during construction in the form of seepage or surface runoff and suitable control of groundwater should be anticipated and planned for accordingly before the start of construction. The Contractor should be responsible for selecting and implementing an appropriate groundwater control system. The Contractor should have previous groundwater control experience on sites with similar conditions. Suitable silt and sediment traps should be incorporated into the dewatering system.

5.5 Slopes and Temporary Excavations

The Owner and the Contractor should make themselves aware of and become familiar with applicable local, state, and federal safety regulations, including current OSHA excavation and trench safety standards. Construction site safety generally is the sole responsibility of the Contractor. The Contractor shall also be solely responsible for the means, methods, techniques, sequences and operations of construction operations. We are providing the following information solely as a service on this project and, under no circumstances, should our provision of the following information be construed to mean that we are assuming responsibility for construction site safety or the Contractor's activities; such responsibility is not implied and should not be inferred.

The Contractor should be aware that slope height, slope inclination, and excavation depths (including utility trench excavations) should in no case exceed those specified in local, state, or federal safety regulations; e.g., OSHA Health and Safety Standards for Excavations, 29 CFR Part 1926, or successor regulations. For this site, the overburden soil encountered in our exploratory program is a combination of cohesive and granular soil. We anticipate that OSHA will classify these materials as Types A and C, respectively. OSHA recommends a maximum slope inclination of ¾H:1V for Type A and 1½H:1V for Type C soil under ideal conditions.

5.6 Below-Grade Walls

The lateral earth pressure against below-grade walls is a function of the rigidity of the wall, the nature of the backfill material, the slope of the top surface of the retained soil and surcharge loads. For design of cantilever retaining walls, the following soil parameters may be used:

Table 5.6.1 - Cantilever Wall Lateral Earth Pressures

Coefficient of at rest earth pressure 0.47

Coefficient of net passive earth pressure 1.5

Friction angle of backfill 32 degrees

Total unit weight of backfill 120 pcf

Interface friction between bottom of wall and subgrade should only be considered where pier support is not present. Any possible surcharge loads should be included in the design of all earth-retaining structures.

5.7 MBC Seismic Considerations

The seismic design category can be determined with noted exceptions following Section 1613 of the 2015 Michigan Building Code. The Risk Category under Section 1613.3.5 shall be determined by a licensed structural engineer. Based on the subsurface conditions identified in the soil borings, our experience with the geological conditions in the site vicinity and the procedures outlined in Section 1613 of the 2015 Michigan Building Code and Chapter 20, Table 20.3-1 of ASCE 7, we recommend assigning a Site Class D to this site. A Site Class D designates a stiff soil profile in the upper 100 ft with average SPT uncorrected N-values between 15 and 50 in granular soil and average undrained shear strengths, su, between 1,000 and 2,000 psf in cohesive soil. Recommended seismic ground motion values are provided in Table No. 5.7.1.

Table No. 5.7.1 - Recommended Seismic Ground Motion Values

2015 Michigan Building Code Values Short Period (0.2 sec)

Long Period (1 sec)

Spectral Response Acceleration, Figure 1613.3.1(1 and 2), %g

Ss = 5 Sl = 1

Seismic Site Coefficient, Table 1613.3.3(1 and 2) Fa = 1.6 Fv = 2.4 Maximum Considered Spectral Response Acceleration, Equations 16-37 and 16-38

SMS = 0.080g SMl = 0.024g

5% Damped Spectral Response Acceleration, Equations 16-39 and 16-40

SDS = 0.053g SDl = 0.016g

6.0 CLOSURE

In this report, descriptions of the geotechnical investigation, encountered conditions and recommendations for the design of foundations and earth-related structures have been provided. The limitations of this study are described in the Appendix.

The recommendations presented in this report are based upon a limited number of subsurface samples obtained from various sampling locations. The samples may not fully indicate the nature and extent of the variations that actually exist between sampling locations.

For that reason, among others, we strongly recommend that a qualified geotechnical firm be retained to observe earthwork construction. If variations or other latent conditions become evident during construction, it will be necessary for us to review these conditions and our recommendations as appropriate.

TITLE: BORING LOCATION PLAN – SITE VICINITY PROJECT: BRHRA WATERFALL OVERLOOK PLATFORMS AND ACCESS STAIRS – PHASE 2

SCALE: AS DATE: 12/23/2024 PROJECT NO.: 241747

FIG. NO.: 1 DR. BY: ES REV. BY: JMS

SANDSTONE

FALLS

RAINBOW

FALLS

LAKE SUPERIOR LEGEND

AREA OF INVESTIGATION (TYP)

NOTE: AERIAL IMAGE FROM GOOGLE EARTH

TITLE: BORING LOCATION PLAN – SANDSTONE FALLS PROJECT: BRHRA WATERFALL OVERLOOK PLATFORMS AND ACCESS STAIRS – PHASE 2

SCALE: NA DATE: DECEMBER 23, 2024 PROJECT NO.: 241747

FIG. NO.: 2 DR. BY: ES REV. BY: JMS

B-1

LEGEND

BORING LOCATION (TYP)

NOTE: BASE PLAN PROVIDED BY MJ ENGINEERING, ARCHITECTURE,

LANDSCAPE ARCHITECTURE, AND LAND SURVEYING, P.C.

HA-7

HA-4

HA-6

HA-3

HA-2

HA-1

HA-5

SECTION A-A

SITE VICINITY

TITLE: BORING LOCATION PLAN – RAINBOW FALLS PROJECT: BRHRA WATERFALL OVERLOOK PLATFORMS AND ACCESS STAIRS – PHASE 2

SCALE: NA DATE: DECEMBER 23, 2024 PROJECT NO.: 241747

FIG. NO.: 3 DR. BY: ES REV. BY: JMS

HA-13

HA-11

HA-13A

HA-9 HA-8

HA-10

B-2

LEGEND

BORING LOCATION (TYP)

NOTE: BASE PLAN PROVIDED BY MJ ENGINEERING, ARCHITECTURE,

LANDSCAPE ARCHITECTURE, AND LAND SURVEYING, P.C.

SECTION B-B

HA-12A

HA-12

SITE VICINITY

APPENDIX

• Limitations

• Test Drilling and Sampling Procedures

• Boring Log Terminology and Classification Outline

• Boring Logs

• Laboratory Summary Table

• MDOT Gradation Summary

LIMITATIONS

Soil Variations

The recommendations in this report are based upon the data obtained from the soil borings.

This report does not reflect variations which may occur between these borings, and which would not become evident until construction. If variations then become evident, it would be necessary for a re-evaluation of recommendations of this report, after performing on-site observations.

Warranties

We have prepared this report in accordance with generally accepted soil and foundation engineering practices. We make no other warranties, either expressed or implied, as to the professional advice provided under the terms of our agreement and included in this report.

This report is prepared exclusively for our client and may not be relied upon by other parties without written consent from our office.

Boring Logs

In the process of obtaining and testing samples and preparing this report, we follow reasonable and accepted practice in the field of soil engineering. Field logs maintained during drilling describe field occurrences, sampling locations, and other information. The samples obtained in the field are subjected to additional testing in the laboratory and differences may exist between the field logs and the final logs. The engineer reviews the field logs and laboratory test data, and then prepares the final boring logs. Our recommendations are based on the contents of the final logs.

Review of Design Plans and Specifications

In the event that any changes in the design of the building or the location, however slight, are planned, our recommendations shall not be considered valid unless modified or approved in writing by our office. We recommend that we be provided the opportunity to review the final design and specifications in order to determine whether changes in the original concept may have affected the validity of our recommendations, and whether our recommendations have, in fact, been implemented in the design and specifications.

TEST DRILLING AND SAMPLING PROCEDURES

Test Drilling Methods:

X Hollow stem auger, ASTM D6151 Mud rotary, ASTM D5783 Casing advancer, ASTM D5872 Rock coring, ASTM D2113

X Core/Hand Auger

Note: Cone penetration test data can be used to interpret subsurface stratigraphy and can provide data on engineering properties of soils. The ASTM procedure does not include a procedure for determining soil classification from CPT testing. Soil classifications shown on CPT logs are based on published procedures and are not based on physical ASTM soil classification tests.

Sampling Methods:

X SPT, ASTM D1586, Auto hammer (140 lb., 30" drop, 2" OD split spoon sampler) X Thin-walled tube sampler (Shelby), ASTM D1587

Note: The number of hammer blows required to drive the SPT sampler 12 inches, after seating 6 inches, is termed the soil N-value and provides an indication of the soil's relative density and strength parameters at the sample location. SPT blow counts in 6 inch increments are recorded on the boring logs.

Drill Rig:

CME 55 (ATV)

X Acker Renegade (ATV) CME 45 Truck Geoprobe 7822 (ATV) Geoprobe Rotary Sonic

Boreholes Backfilled With:

X Excavated soil Cement bentonite grout Piezometer or Monitoring Well (see notes on logs) Concrete or asphalt patch where appropriate

Sample Handling and Disposition:

X Samples labeled, placed in jars, returned to MTC Laboratory X Discard after 60 days

S-1

S-2

S-3

S-4

S-5

S-6 S-6A S-6B

S-7

S-8

S-9

S-10

S-11

S-12

0.3

3.0

40.0

4" Topsoil

Brown silty SAND; mostly fine sand, little silty fines, trace fine gravel, moist with frequent root fragments Grades with occasional root fragments from 1' to 2'

Red brown lean CLAY; mostly clayey fines, trace coarse to fine sand, moist

Grades with trace coarse to fine gravel

Grades with occasional sand seams at 14.8'

Grades without sand, without gravel, and without sand seams

4.0

3.0

4.25

4.0

2.5

2.0

2.0

1.75

2.0

12.4

18.0

17.6

SM

CL

2-2-3 N=5

8-10-10 N=20

4-6-9 N=15

5-8-10 N=18

7-8-14 N=22

58/6" 50/5" 70/6"

15-5-8 N=13

38-30-7 N=37 7-7-7 N=14

5-7-8 N=15

4-5-7 N=12

5-7-8 N=15

1.5

1.5

1.5

1.5

1.5

0.1 0.0 0.0

1.5

0.0

1.5

1.5

1.5

1.5

S-4 Lab Testing: Atterberg Limits (ASTM D4318):

LL=24, PL=13, PI=11

Driller noted possible coarse gravel / COBBLE at 16.2' to 16.5'

S-6, S-6A, S-6B: SPT

refusal; possible coarse gravel / COBBLE

Two shelby tube attempts at 23.5' with immediate refusal

S-9 Lab Testing: Atterberg Limits (ASTM D4318):

LL=32, PL=14, PI=18

One shelby tube attempt at 26.5' with immediate refusal

S-11 Lab Testing:

Atterberg Limits (ASTM

D4318): LL=29, PL=14,

PI=15

Dia. Groundwater, ft.

Depth, ft.

Sandstone Falls, Offset 15'S, 10'E of SE Corner of BenchNotes:

Drill Type:

Crew Chief:

Project:

11/05/2024

JSNB

Type

End

Datum:879.5 ft

Client:

4 1/4" During

DateElevation:

ES

Site Plans

MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C.

Plugging Record: Backfilled borehole with compacted cuttings. Cave in at

65.0 ft.

Ironwood, Michigan

Shelby 3"

Date Begin:

Core

Tube

SPT Hammer

Sampler

Auto

HSA

2"

Location:

NA

Date End: 11/05/2024

Casing

Tooling

Coordinates:

Field Eng.:

Acker Renegade

Rev. By:

Depth Drilled: 80.0 ft.

SPT

BRHRA Waterfall Overlook Platforms and Access Stairs - Phase 2

Delayed Groundwater, ft.

Component Percentages: Trace < 5%, Few 5-10%, Little 15-25%, Some 30-45%, Mostly 50-100% QP = Calibrated Penetrometer (tons/sq. ft.)

Sample

Number

241747

Boring No.:

LOG

OF

BORING

Project No.:

Depth

FT.

Elev.

FT. *DESCRIPTION QP

tsf

DD

pcf

MST

*USCS

Group

Symbol

Penetration

(Blows Per 6")

ASTM D 1586

Recov.

FT. REMARKS

Sheet: 1 of 2

B-1

* Visual estimate following ASTM D 2488 unless laboratory testing has been performed. Stratification changes are approximated between samples.

878.5

877.5

876.5

875.5

874.5

873.5

872.5

871.5

870.5

869.5

868.5

867.5

866.5

865.5

864.5

863.5

862.5

861.5

860.5

859.5

858.5

857.5

856.5

855.5

854.5

853.5

852.5

851.5

850.5

849.5

848.5

847.5

846.5

845.5

844.5

843.5

842.5

841.5

840.5

839.5

S-13

S-14

S-15

S-16

S-17

S-18

S-19

S-20

42.0

47.0

67.0

69.0

72.0

80.0

Red brown lean CLAY; mostly clayey fines, moist

Red brown SAND with silt; mostly fine sand, few silty fines, moist

Red brown silty SAND; mostly fine sand, little silty fines, moist

Grades with some silty fines

Red brown sandy SILT; mostly silty fines, some fine sand, wet

Red brown lean CLAY; mostly clayey fines, trace coarse to fine sand, moist

Red brown silty SAND; mostly fine sand, some silty fines, moist

End of Boring

4.5

CL

SP-SM

SM

ML

CL

SM

12-18-24 N=42

17-20-23 N=43

15-22-28 N=50

14-17-20 N=37

12-17-19 N=36

17-15-21 N=36

28-35-50 N=85

21-33-42 N=75

1.5

1.5

1.5

1.5

1.5

1.5

1.5

1.5

Auger refusal at 78.5' on very dense sand

QP = Calibrated Penetrometer (tons/sq. ft.)Component Percentages: Trace < 5%, Few 5-10%, Little 15-25%, Some 30-45%, Mostly 50-100%

Sample

Number

241747

Boring No.:

LOG

OF

BORING

Project No.:

Depth

FT.

Elev.

FT. *DESCRIPTION QP

tsf

DD

pcf

MST

*USCS

Group

Symbol

Penetration

(Blows Per 6")

ASTM D 1586

Recov.

FT. REMARKS

Sheet: 2 of 2

B-1

* Visual estimate following ASTM D 2488 unless laboratory testing has been performed. Stratification changes are approximated between samples.

838.5

837.5

836.5

835.5

834.5

833.5

832.5

831.5

830.5

829.5

828.5

827.5

826.5

825.5

824.5

823.5

822.5

821.5

820.5

819.5

818.5

817.5

816.5

815.5

814.5

813.5

812.5

811.5

810.5

809.5

808.5

807.5

806.5

805.5

804.5

803.5

802.5

801.5

800.5

799.5

S-1

S-2

S-3

S-4

S-5

S-6

S-7

U-8

S-9

U-10

S-11

S-12

0.3

2.0

8.0

13.5

17.0

19.5

33.8

4" Topsoil

Brown silty SAND; mostly fine sand, some silty fines, moist with frequent root fragments

Red brown poorly graded SAND with gravel; mostly coarse to fine sand, little coarse to fine gravel, moist

Brown poorly graded SAND; mostly medium to fine sand, few coarse to fine gravel, moist with occasional clay seams

Red brown poorly graded SAND with silt;

mostly fine sand, few silty fines, wet

Red brown SILT with sand; mostly silty fines, little fine sand, wet

Red brown lean CLAY; mostly clayey fines, moist

Grades with trace fine gravel

Grades with occasional silt seams

Red brown SILT; mostly silty fines, moist

0.5

1.25

1.5

19.7

SM

SP

SP

SP-SM

ML

CL

ML

2-2-5 N=7

10-9-7 N=16

18-11-8 N=19

8-9-8 N=17

3-4-5 N=9

10-3-2 N=5

2-3-4 N=7

Shelby

5-6-8 N=14

Shelby

6-17-29 N=46

20-27-34 N=61

1.0

1.5

1.5

1.5

1.5

1.5

1.5

0.0

1.5

0.0

1.5

1.3

S-1: Poor recovery;

possible coarse gravel /

COBBLE

Driller noted possible coarse gravel / COBBLE from 2' to 8'

S-7 Lab Testing: Atterberg Limits (ASTM D4318):

LL=31, PL=14, PI=17

U-8: No recovery.

U-10: No recovery.

Dia. Groundwater, ft.

Depth, ft.

Rainbow Falls, Offset 6.5'N, 16'W of Point of MapNotes:

Drill Type:

Crew Chief:

Project:

JSNB

Type

End

Datum:760 ft

Client:

4 1/4" During

DateElevation:

ES

Site Plans

MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C.

Plugging Record: Backfilled borehole with compacted cuttings and one bag of well sand. Cave in at 14.0 ft.

Ironwood, Michigan

Shelby 3"

Core

Tube

SPT Hammer

Sampler

Auto

HSA

2"

Location:

Casing

Tooling

Coordinates:

Field Eng.:

Acker Renegade

Rev. By:

Depth Drilled: 54.5 ft.

SPT

BRHRA Waterfall Overlook Platforms and Access Stairs - Phase 2

Delayed Groundwater, ft.

Component Percentages: Trace < 5%, Few 5-10%, Little 15-25%, Some 30-45%, Mostly 50-100% QP = Calibrated Penetrometer (tons/sq. ft.)

Sample

Number

241747

Boring No.:

LOG

OF

BORING

Project No.:

Depth

FT.

Elev.

FT. *DESCRIPTION QP

tsf

DD

pcf

MST

*USCS

Group

Symbol

Penetration

(Blows Per 6")

ASTM D 1586

Recov.

FT. REMARKS

Sheet: 1 of 2

B-2

* Visual estimate following ASTM D 2488 unless laboratory testing has been performed. Stratification changes are approximated between samples.

759.0

758.0

757.0

756.0

755.0

754.0

753.0

752.0

751.0

750.0

749.0

748.0

747.0

746.0

745.0

744.0

743.0

742.0

741.0

740.0

739.0

738.0

737.0

736.0

735.0

734.0

733.0

732.0

731.0

730.0

729.0

728.0

727.0

726.0

725.0

724.0

723.0

722.0

721.0

720.0

11/06/2024Date Begin: Date End: 11/07/2024

S-13

S-14

S-15 54.5

Grades with few fine sand, trace fine gravel

End of Boring

24.2

ML

20-27-29 N=56

12-16-18 N=34

14-18-23 N=41

1.5

1.5

1.5

Auger refusal on very dense silt

QP = Calibrated Penetrometer (tons/sq. ft.)Component Percentages: Trace < 5%, Few 5-10%, Little 15-25%, Some 30-45%, Mostly 50-100%

Sample

Number

241747

Boring No.:

LOG

OF

BORING

Project No.:

Depth

FT.

Elev.

FT. *DESCRIPTION QP

tsf

DD

pcf

MST

*USCS

Group

Symbol

Penetration

(Blows Per 6")

ASTM D 1586

Recov.

FT. REMARKS

Sheet: 2 of 2

B-2

* Visual estimate following ASTM D 2488 unless laboratory testing has been performed. Stratification changes are approximated between samples.

719.0

718.0

717.0

716.0

715.0

714.0

713.0

712.0

711.0

710.0

709.0

708.0

707.0

706.0

1.0

4.5+

4.5+

Auger refusal at 8.6' on hard clay

0.3

1.9

3.5

8.6

3" Topsoil

Red brown lean CLAY; mostly clayey fines, few coarse to fine gravel, few coarse to fine sand, moist with frequent root fragments Grades without root fragments at 1'

Red brown silty SAND; mostly coarse to fine sand, little silty fines, moist

Grades with frequent clay seams at 3' with occasional wet silty sand seams

Red brown lean CLAY; mostly clayey fines, few coarse to fine sand, few coarse to fine sand, moist with frequent sand seams

Grades without gravel, and without sand seams at 5.7' Grades with trace medium to fine sand at 6'

End of Boring

A-1

A-2

CL

SM

CL

QP = Calibrated Penetrometer (tons/sq. ft.)Component Percentages: Trace < 5%, Few 5-10%, Little 15-25%, Some 30-45%, Mostly 50-100%

3 1/4"

Location:

4.7

Dia. Groundwater, ft.

Depth, ft.

Sandstone Falls, Offset 3'N of North Edge of StairsNotes:

Datum:

Drill Type:

Crew Chief:

Project:

Core

Depth Drilled: 8.6 ft.

Plugging Record: Backfilled borehole with compacted cuttings.

JS

Type

End

Tube

Hand AugerSampler

Ironwood, Michigan

Casing

Tooling

Coordinates:

Field Eng.:

861 ft

Client:

SPT Hammer

3During

DateElevation:

ES

Site Plans

Hand Auger

Rev. By:

MJ Engineering, Architecture, Landscape Architecture, and Land Surveying, P.C.

BRHRA Waterfall Overlook Platforms and Access Stairs - Phase 2

Delayed Groundwater, ft.

HA-1

Project No.:

QP

tsf

MST

REMARKS

* Visual estimate following ASTM D 2488 unless laboratory testing has been performed.