idr-srao-tcrown1_geo_memo.pdf

158377846

M E M O R A N D U M

Western Federal Lands Highway Division 610 E. Fifth Street

Vancouver, WA 98661

DATE: March 12, 2024

TO: Sean Hayter Project Manager

FROM: Todd Hansen Geological Engineer

SUBJECT: Final Geotech Recommendations GM0824 Crown Point Trail

ID BOR SRAO TCROWN(1)

Cascade, Idaho

INTRODUCTION

The Crown Point Trail is a 2.7-mile multi-use trail on repurposed railroad bed located along the Lake Cascade shoreline, a reservoir managed by the Bureau of Reclamation. The project is located approximately 80 miles north of Boise, Idaho on State Highway 55 in the town of Cascade, Valley County, Idaho. The aggregate-surfaced trail is popular year-round for various activities, including hiking, mountain biking, horseback riding, snowshoeing, snowmobiling, and cross-country skiing.

This memorandum provides our final geotechnical recommendations for repairing a localized fill slope damaged by erosion from uncontrolled surface runoff. This localized slope repair is part of a larger, comprehensive project to improve an existing recreational trail.

Recommendations are also provided for overside drainage methods at the fill slope repair.

PROJECT SCOPE

The overall proposed project scope includes creating a “firm and stable” trail surface for 2.7 miles, expanding and improving the existing trailhead, formalizing a beach access trail, repairing a slope erosion issue, and adding a vault toilet. This memo presents general conditions and only provides recommendations for the slope erosion issues.

GEOLOGIC CONDITIONS

The Lake Cascade area has two dominant geologic features, the Idaho Batholith and the Columbia River Basalt. The Idaho Batholith consists of a large intrusive complex of igneous rocks formed from 40 to 100 million years ago. Rocks of the Idaho Batholith consist primarily

U.S. Department of Transportation

Federal Highway Administration of coarse-grained granitic rocks such as granodiorite and quartz diorite. Near the western edge of the batholith, existing rocks were metamorphosed into schists and gneisses by intrusion of the batholith. Large portions of West Mountain are composed of these metamorphic rocks.

The Columbia River Basalt is found throughout western Idaho, eastern Oregon, and Washington. The Columbia River Basalts erupted from fissures to the west and formed an extensive plateau that lapped onto the western edge of the Idaho Batholith. Rocks of the Columbia River Basalt group consist of Miocene-age (5 to 17 million years old) basalt flows that are thousands of feet thick. Basalt is present at the northern end of the Cascade Dam near the project site.

The structural geology is dominated by the Long Valley Fault System. This fault zone formed north-trending linear valleys and mountain ridges in west central Idaho. Lake Cascade is located in a structural graben (valley) formed by down-dropping along the Long Valley Fault.

The sedimentary basin fill in the area is more than 7,000 feet deep as a result of down-faulting of the valley floor. The steep, linear mountain front along West Mountain was formed by uplift on the Long Valley fault that began between 14 and 10 million years ago. Glaciers that advanced down from the crest of West Mountain deposited moraines and out-wash. Much of the valley surrounding Lake Cascade is filled with glacial outwash. Some of these outwash terraces have since been incised by more recent stream activity.

As mapped by the Idaho Geological Survey on the “Surficial Geologic Map of the Cascade Quadrangle, Valley County, Idaho” digital web map (DWM) 72, there are two surficial units exposed along the trail alignment. Surficial units in Figure 1 consist of “made land” (m), alluvium (Qal) and colluvium derived from granitic rocks (Qcg). Granite and basalt bedrock are not mapped along the trail route on DWM-72 but were observed in the site scoping visit on August 17, 2022.

Figure 1 – Geologic map of Crown Point Trail (DWM-72, 2006).

Geologic conditions exposed within the existing trail range from constructed fills to granite and basalt. Overburden soils derived from the bedrock are generally sandy grus soil to silty gravel.

The granite bedrock underlies the majority of the trail and ranges in composition from residual, very weak rock (R1) to strong rock (R4), intact massive granite outcrops and corestone boulders. Corestones are defined as the result of deep weathering of rock, which is then eroded away to expose intact, rounded boulders which can become buried later by soils or fill.

The basalt bedrock outcrops are slightly weathered, strong and moderately fractured in rock cuts with colluvial debris consisting of cobbles to small boulders (approximately 2-foot diameter or smaller) collected at the slope toes and in ditches.

HISTORIC RAILROAD CONSTRUCTION

Between 1912 and 1914, the Oregon Short Line Railroad (Union Pacific) constructed track from Smith’s Ferry through the new depot at Cascade that ended at McCall. The railroad alignment between Cascade and McCall was known as the Idaho-Northern Branch, a portion of which has now become the Crown Point Trail.

Construction of this railroad grade used typical cut and fill methods for that time and followed the most efficient route by utilizing large rock cuts and fill slopes in the most economical way possible. Therefore, the historic rail grade likely includes large rock in slope fills and used

Qcg

Qal m

-z Cl excavated materials to balance earthwork requirements. Large rock would most likely be found at the base of the fills, and intact rock will either be basalt or granite.

Most of the existing trail surface appears to be from the original railroad construction, which is locally sourced decomposed granite (grus). Surficial inspection of large fill slopes appears to consist of decomposed granite or weathered granite rock fill. Basalt outcrops along an approximate 800-foot section of trail, exposed in a rock cut and abandoned rock quarry.

Where the trail passes adjacent to basalt outcrops, the bed appears to be poorly-drained silty gravel soil with numerous basalt rocks in the ditches along the trail shoulder. Proposed new construction for a parking lot or spur trail should anticipate encountering granite rock ranging from predominantly decomposed and rippable to intact, hard rock that would require specific excavation requirements (i.e., pneumatic hammers or blasting).

TRAIL SURFACE AND SUBSURFACE CONDITIONS

No samples were collected during the scoping trip on August 17, 2022 and a subsurface drilling program is not planned at this time because the project consists of improving the travel surface and repairing the fill slope erosion. A site visit on September 12, 2023 collected grab samples of the surface material, including the granite-derived grus sand and silty gravel soils.

Subgrade density was investigated using the dynamic cone penetrometer (DCP) method to determine underlying soil strength by measuring the penetration of the device into the soil after each hammer blow. The test is performed by driving a metal cone into the ground by repeatedly striking it with a 17.6 lbs (8 kg) weight dropped a distance of 2.26 feet (575 mm).

The cone penetration is measured after 10 blows and is recorded to provide a continuous measure of soil strength to up to 5 feet below the ground surface. Test results can then be correlated to California Bearing Ratios, in-situ density, resilient modulus, and bearing capacity.

Full results of the DCP field test data can be found in Attachment 2. Table 1 below lists the location, and DCP derived minimum values for California Bearing Ratio (CBR) and bearing capacity for the upper 10-inches of tested profile.

Table 1 – DCP test number, locations and values within upper 10-inches of subgrade.

DCP Test Lat/Long CBR Bearing Capacity (psf) 1 44.526257, -116.055600 20 3,600 2 44.526279, -116.055895 28 6,100 3 44.526183, -116.055266 17 3,300 4 44.533360, -116.065593 8 2,000 5 44.533266, -116.065643 8 2,000 6 44.552951, -116.061924 15 3,000 7 44.556527, -116.062946 16 3,100

Figure 2 – South Trailhead DCP 1, 2 & 3 testing locations.

Figure 3 – Oblique view of rock cut DCP 4 & 5 testing locations.

Figure 4 – Oblique view of full embankment, fill erosion feature DCP 6 testing location.

Figure 5 - North Trailhead DCP 7 testing location.

In addition to the DCP test results, the following descriptions summarize observations and anticipated conditions of the trail soil subgrade.

Trail Gravel Surface

The gravel trail was constructed atop the old railroad bed and is a smoothly packed sand surface. Some improvements were made to the wearing surface after the railroad abandonment, though the subgrade is performing well, with limited, minor ruts . Areas with drainage issues appear to be the primary locations that required subexcavation and positive drainage improvements.

We anticipate trail areas that required rock cuts will likely encounter shallow weathered to intact rock within the upper 2-feet beneath the gravel surface and in fill areas the depth to intact bedrock will likely follow the ground contours prior to the railroad construction. The deepest fills are found near Grandmas Creek and at mile post 2.4.

Soft Subgrade Trail Surface Approximately 0.9-mile from the southern trail the trail passes through a rock cut. This section of trail is experiencing the most severe rutting from poor subgrade. Previously, this section was referred to as the “clay” trail surface in the preliminary report, and the subsequent bulk sample is identified as “clay gravel”. The laboratory test results indicate the fine-grained constituent is silt and the USCS field identification of clay has been corrected in Table 1 below.

The trail is susceptible to pumping and loss of subgrade support when loaded while saturated, and reestablishing drainage in this trail section should prevent future surface rutting and damage. Subexcavation to replace the soft subgrade soil will likely encounter bedrock within the upper 2-feet. If encountered within the planned replacement depths, additional excavation into the bedrock is unnecessary as it is a suitable subgrade bearing material.

Laboratory Test Results

Representative bulk samples were collected for the soft subgrade at the rock-through-cut and for the decomposed granite trail surface and erosional feature. The two bulk samples were submitted for material property testing and the results are summarized below and included in Attachment 1 – Laboratory Test Result.

Table 2 – Summary of laboratory test results.

Bulk Sample R-value LL / PI AASHTO USCS

“Clay Gravel” N/A 36 / 14 A-2-6 (0) GM, Silty GRAVEL with sand “North Gate &

Erosional Feature” 64 N/A A-2-4 (0) SM, Silty SAND

GROUNDWATER AND RESERVOIR LEVELS

No springs or indications of groundwater were observed during the scoping trip in August 2022. Historically the railroad alignment was constructed using full embankment fills to cross drainage channels which were later inundated by the reservoir. The trail crosses two drainages, Grandma Creek and an unnamed inlet, and no embankment cross culverts were observed in the field.

Lake Cascade is a shallow, man-made reservoir managed by the Bureau of Reclamation and Idaho State Parks. At the time of the scoping visit, the reservoir appeared to be near full capacity, and indications of shoreline erosion from wave action were apparent. Shoreline erosion or loss of ground to wave action are not part of this scoped project.

FILL SLOPE REPAIR

The historic railroad fill embankment appears to be constructed using locally-sourced materials from the nearby rock cuts and that a uniform layer of basalt rip-rap fill forms the base beneath the granite rock fill prism above. The basalt rock fill is visible along the entire fill base, except for the section where the granite rock fill has eroded downslope.

Special Rock Embankment

Uncontrolled surficial runoff is causing localized erosion of the granite rock fill. A special rock embankment (SRE) is proposed as the repair because it can be placed without the need for specialized facing or geosynthetic reinforcements.

Placement of the SRE in the erosional gulley will stabilize and buttress the fill slope and allow for proper drainage. A Class 1, Type A, nonwoven separation fabric should be installed between the existing fill and SRE to prevent migration of fine-grained soils into the rock embankment. The maximum slope for an SRE is 1V:1H and minimum embedment of 2-feet at the base of the slope. The base of the SRE will be constructed above the ordinary high-water mark of Lake Cascade to prevent encroachment into the lake and prevent the need for permits to construct below ordinary high water mark.

Overside Drainage Chute Option

Storm runoff appears to have eroded through a windrow berm of soil along the edge of the trail. This runoff then was able to flow down the full embankment causing the observed fill slope erosion. To prevent future erosion of the special rock embankment repair, an overside drainage flume or corrugated steel half-pipe can capture the surface runoff and direct it down to the lake. This flume drainage option will be anchored at the inlet and at intervals along the pipe rundown over the special rock embankment.

Examples of an overside drain are shown in Figure 6 below. The intent is to direct water over the rock and discharge at the SRE toe to dissipate flow energy without further undermining of the granite rock fill slope.

Figure 6 – Example of half-culvert overside drain drawing and as-constructed plans.

CONSTRUCTION CONSIDERATIONS

Equipment will need access the top and base of the fill slope to construct the SRE and overside drain. It is anticipated that no equipment will be able to perform construction working from the beach below the repair. Repairs should assume that all work is performed from the trail surface. This means the excavation and mechanical placement of the rock embankment will be done performed from above.

During construction:

Do not unnecessarily clear vegetation on the fill slope and surrounding the erosion site.

With the exception of the slope repair area, do not allow construction traffic or equipment to track on the fill slope.

Fluctuating water levels in the reservoir could cause rapid changes in porewater pressure at the shoreline and lower reservoir rim. The granite-sourced sandy soil (grus) deposits along the shoreline are anticipated to be moderate- to well-drained. Based on observations of the existing fill embankment along the shoreline, it is apparent that some combination of wave action and fluctuating reservoir levels is eroding the base of the existing fill in other areas as well. The proposed SRE repair of the lost fill section will stabilize the slope in that location and not address the issues that the ongoing shoreline erosion is continuing to remove from the toe of the historic railroad fill. Field observations of basalt rock at the base of the trail fill embankment were likely placed during the original railroad construction. The base rock is not preventing continued erosion to propagate along the shoreline and laterally into the base of the fill slope. While these existing conditions are not part of the repair they should be monitored during construction to ensure the conditions do not deteriorate.

CLOSING

Please contact Todd Hansen at (360) 619-7903 or Todd.Hansen@dot.gov with any questions regarding this preliminary memorandum.

CC:

Andrew Roseman-Hanauer, DES Benjamin White, ENV Mark Swank, GEO

REFERENCES

AASHTO LRFD Bridge Design Specifications, Seventh Edition (2014) American Association of State Highway and Transportation Officials, Washington, D.C.

Breckenridge, R.M., and Othberg, K.L., Idaho Geological Survey, “Surficial Geologic Map of the Cascade Quadrangle, Valley County, Idaho”, Digital Web Map DWM-72, 2006, Scale 1:24000.

ATTACHMENT 1 – LABORATORY TEST RESULTS

ATTACHMENT 2 – DYNAMIC CONE PENETROMETER TEST RESULTS

ATTACHMENT 1 – LABORATORY TEST RESULTS

Western Federal Lands

Project No.: ID BOR SRAO TCROWN(1) Sample ID: W-23-1643-GS

Materials Laboratory

ISO/IEC 17025:2017 Accredited Date Distributed: 10/10/2023

Table of Contents

Station:

Material Description: SO-PS

MilePost:

Offset:

Intended Use:

Remarks:

Source Name:

Source Location:

Sample Location:

Submitted By: M Chen

Quantity Represented:

Item No.:

Field Sample No.: 1,3

Lot No.:

Date Sampled: 9/12/2023

Depth: 1 Hole No.: North Gate & Erosional Feature

Project Name: CROWN POINT TRAIL AND

PARKING AREA

W-23-1643-GS _________________________________________________________________ 2

W-23-1643-GS _________________________________________________________________ 6

AASHI□

ACCREDITED

Station:

Project No.: ID BOR SRAO TCROWN(1) Sample ID: W-23-1643-GS

Materials Laboratory

ISO/IEC 17025:2017 Accredited Date Distributed: 10/10/2023

Material Description: SO-PS

MilePost:

Offset:

Intended Use:

Remarks:

Source Name:

Source Location:

Sample Location:

Submitted By: M Chen

Quantity Represented:

Item No.:

Field Sample No.: 1,3

Lot No.:

Date Sampled: 9/12/2023

Depth: 1 Hole No.: North Gate & Erosional Feature

Project Name: CROWN POINT TRAIL AND

PARKING AREA

Unit of MeasureResult

R value by Exudation @ 300 psi 64

Density @ R Value 115.7 pcf

Moisture @ R Value 12.3 %

Methods: T 190 AASHTO Test Date: 10/2/2023 Tested By: Rob Lange

Comments:

Test Validated By: Walter Stong Validated Date: 10/10/2023

Version 1

Unit of MeasureResult

Specific Gravity @ 20°C 2.674

Methods: AASHTO T 100 - Specific Gravity of Soils Test Date: 10/3/2023 Tested By: Rob Lange

Comments:

Test Validated By: Rob Lange Validated Date: 10/4/2023

Version 1

Unit of MeasureResult

Liquid Limit From T 89 Not Run

Plastic Limit from T 90 Non-Plastic

Plasticity Index Not Applicable

Methods: AASHTO T 89 & T 90 - Atterberg Limits Test Date: 10/2/2023 Tested By: Rob LangeVersion 1

All reported results apply to the sample as received.

Page 2 of 4Sample ID: W-23-1643-GS

Con tro lle d C op y

AASHI□

ACCREDITED

I I I

I I I

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Unit of MeasureResult

6" sieve (152.4 mm) % Passing - %

5" sieve (127 mm) % Passing - %

4" sieve (101.6 mm) % Passing - %

3 1/2" sieve (88.9 mm) % Passing - %

3" sieve sieve (76 mm) % Passing - %

2 1/2" sieve (63.5 mm) % Passing - %

2" sieve (50.0 mm) % Passing - %

1 1/2" sieve (37.5 mm) % Passing - %

1" sieve (25.0 mm) % Passing 100.0 %

3/4" sieve (19.0 mm) % Passing 99.9 %

1/2" sieve (12.5 mm) % Passing 99.9 %

3/8" sieve (9.5 mm) % Passing 99.7 %

No. 4 sieve (4.75 mm) % Passing 99.4 %

No. 10 sieve (2.0 mm) % Passing 94.1 %

No. 40 Sieve (0.425 mm) % Passing 53.3 %

No. 200 Sieve (0.075 mm) % Passing 14.9 %

Interpolated 0.020 mm % Passing 9.1 %

Interpolated 0.010 mm % Passing 6.2 %

Interpolated 0.005 mm % Passing 4.8 %

Interpolated 0.002 mm % Passing 2.4 %

Interpolated 0.001 mm % Passing 1.3 %

D10 0.0245 mm

D30 0.1483 mm

D50 0.3663 mm

D60 0.5485 mm

CU 22.423

CC 1.638

Methods: AASHTO T 88 - Particle Size Analysis of Soils Test Date: 10/2/2023 Tested By: Rob Lange

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Version 1

Unit of MeasureResult

Classification A-2-4 (0)

Gravel (2.00 mm and larger) 5.9 %

Coarse sand (2.0 to 0.42 mm) 40.8 %

Fine Sand (0.42 to 0.074 mm) 38.4 %

Silt-clay (0.075mm and smaller) 14.9 %

Methods: AASHTO M 145 - Classification (AASHTO M 145 is not an AAP accredited test)

Test Date: 10/5/2023

Tested By: Rob LangeVersion 1

All reported results apply to the sample as received.

Page 3 of 4Sample ID: W-23-1643-GS

Con tro lle d C op y

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Unit of MeasureResult

Classification SM, Silty sand

Cobbles 0 %

Coarse Gravel 0 %

Fine Gravel 1 %

Coarse Sand 5 %

Medium Sand 41 %

Fine Sand 38 %

D10 0.024 mm

D30 0.148 mm

D50 0.366 mm

D60 0.548 mm

CU 22.6961

CC 0.0402

Methods: ASTM D2487 - (Unified Soils Classification System) Test Date: 10/5/2023 Tested By: Rob Lange

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Version 1

All reported results apply to the sample as received.

Page 4 of 4Sample ID: W-23-1643-GS

Con tro lle d C

Name Units Value

➖➖➖ Results ➖➖➖

Plotting Method Curved

R Value by exudation @ 300 psi [none] 63.79

Density at R Value PCF 115.7

Moisture at R Value % 12.3

Western Fed eral Lands Highway Diivision Materials Testing Laboratory

610 E Fiftlh St, Vancouver, WA 98661

Project No.: ID BOR SRAO TCROWN(1) Sample ID: W-23-1644-GS

Materials Laboratory

ISO/IEC 17025:2017 Accredited Date Distributed: 10/07/2023

Table of Contents

Station:

Material Description: Soil

MilePost:

Offset:

Intended Use:

Remarks:

Source Name:

Source Location:

Sample Location:

Submitted By: M Chen

Quantity Represented:

Item No.:

Field Sample No.: 2

Lot No.:

Date Sampled: 9/12/2023

Depth: 1 Hole No.: Clay Gravel

Project Name: CROWN POINT TRAIL AND

PARKING AREA

W-23-1644-GS _________________________________________________________________ 2

Station:

Project No.: ID BOR SRAO TCROWN(1) Sample ID: W-23-1644-GS

Materials Laboratory

ISO/IEC 17025:2017 Accredited Date Distributed: 10/07/2023

Material Description: Soil

MilePost:

Offset:

Intended Use:

Remarks:

Source Name:

Source Location:

Sample Location:

Submitted By: M Chen

Quantity Represented:

Item No.:

Field Sample No.: 2

Lot No.:

Date Sampled: 9/12/2023

Depth: 1 Hole No.: Clay Gravel

Project Name: CROWN POINT TRAIL AND

PARKING AREA

Unit of MeasureResult

Specific Gravity @ 20°C 2.654

Methods: AASHTO T 100 - Specific Gravity of Soils Test Date: 10/3/2023 Tested By: Rob Lange

Comments:

Test Validated By: Rob Lange Validated Date: 10/4/2023

Version 1

Unit of MeasureResult

Liquid Limit From T 89 36

Plastic Limit from T 90 22

Plasticity Index 14

Methods: AASHTO T 89 & T 90 - Atterberg Limits Test Date: 10/4/2023 Tested By: Rob Lange

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Version 1

Unit of MeasureResult

Classification A-2-6 (0)

Gravel (2.00 mm and larger) 40.8 %

Coarse sand (2.0 to 0.42 mm) 15.0 %

Fine Sand (0.42 to 0.074 mm) 15.6 %

Methods: AASHTO M 145 - Classification (AASHTO M 145 is not an AAP accredited test)

Test Date: 10/5/2023

Tested By: Rob LangeVersion 1

All reported results apply to the sample as received.

Page 2 of 4Sample ID: W-23-1644-GS

Con tro lle d C op y

Unit of MeasureResult

Silt-clay (0.075mm and smaller) 28.7 %

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Unit of MeasureResult

6" sieve (152.4 mm) % Passing - %

5" sieve (127 mm) % Passing - %

4" sieve (101.6 mm) % Passing - %

3 1/2" sieve (88.9 mm) % Passing - %

3" sieve sieve (76 mm) % Passing 100.0 %

2 1/2" sieve (63.5 mm) % Passing 100.0 %

2" sieve (50.0 mm) % Passing 95.3 %

1 1/2" sieve (37.5 mm) % Passing 87.7 %

1" sieve (25.0 mm) % Passing 77.2 %

3/4" sieve (19.0 mm) % Passing 71.3 %

1/2" sieve (12.5 mm) % Passing 63.7 %

3/8" sieve (9.5 mm) % Passing 61.6 %

No. 4 sieve (4.75 mm) % Passing 60.4 %

No. 10 sieve (2.0 mm) % Passing 59.2 %

No. 40 Sieve (0.425 mm) % Passing 44.2 %

No. 200 Sieve (0.075 mm) % Passing 28.7 %

Interpolated 0.020 mm % Passing 23.3 %

Interpolated 0.010 mm % Passing 20.5 %

Interpolated 0.005 mm % Passing 16.1 %

Interpolated 0.002 mm % Passing 10.8 %

Interpolated 0.001 mm % Passing 10.7 %

D10 0.0016 mm

D30 0.0869 mm

D50 0.7705 mm

D60 3.4626 mm

CU 2173.286

CC 1.367

Methods: AASHTO T 88 - Particle Size Analysis of Soils Test Date: 10/2/2023 Tested By: Rob Lange

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Version 1

Unit of MeasureResult

Classification A-2-6 (0)

Gravel (2.00 mm and larger) 40.8 %

Methods: AASHTO M 145 - Classification (AASHTO M 145 is not an AAP accredited test)

Test Date:

Tested By:Version 1

All reported results apply to the sample as received.

Page 3 of 4Sample ID: W-23-1644-GS

Con tro lle d C

Unit of MeasureResult

Coarse sand (2.0 to 0.42 mm) 15.0 %

Fine Sand (0.42 to 0.074 mm) 15.6 %

Silt-clay (0.075mm and smaller) 28.7 %

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Unit of MeasureResult

Classification GM, Silty gravel with sand

Cobbles 0 %

Coarse Gravel 29 %

Fine Gravel 11 %

Coarse Sand 1 %

Medium Sand 15 %

Fine Sand 16 %

D10 0.002 mm

D30 0.087 mm

D50 0.774 mm

D60 3.560 mm

CU 2198.1647

CC 0.0021

Methods: ASTM D2487 - (Unified Soils Classification System) Test Date: 10/5/2023 Tested By: Rob Lange

Comments:

Test Validated By: Rob Lange Validated Date: 10/5/2023

Version 1

All reported results apply to the sample as received.

Page 4 of 4Sample ID: W-23-1644-GS

Con tro lle d C

ATTACHMENT 2 – DYNAMIC CONE PENETROMETER TEST RESULTS

DCP 1 TEST DATA

File Name: South TH Parking Lot, soft spot

Project: Crown Point Trail Date: 11-Sep-23 Location: South P-Lot soft pumping by kiosk Soil Type(s): Type in the soil type

No. of Accumulative Type of Blows Penetration Hammer

(mm)

10 20 2

10 32 2

10 40 2

10 52 2

10 65 2

10 75 2

10 87 2

10 98 2

10 157 2

10 219 2

10 257 2

10 304 2

10 353 2

10 385 2

10 406 2

10 424 2

10 433 2

10 2

10 2

10 2

10 2

10 2

0.1 1.0 10.0 100.0

0.1 1.0 10.0 100.0

D E

P T

H in

CBR

D E

P T

H m m

0 2000 4000 6000 8000 10000 12000

D E

P T

H in

BEARING CAPACITY, psf

Based on approximate interrelationships of CBR and Bearing values (Design of Concrete Airport Pavement, Portland

Cement Association, page 8, 1955)

10.1 lbs.

17.6 lbs.

Both hammers used

Soil Type

CH

CL

All other soils

Hammer

[2

I

I ,/

I t_ L -, I - ~

Ii;.

I

DCP 2 TEST DATA

File Name: South TH Parking Lot

Project: Crown Point Trail Date: 12-Sep-23 Location: South P-Lot old fill Soil Type(s): Type in the soil type

No. of Accumulative Type of Blows Penetration Hammer

(mm)

10 53 2

10 84 2

10 111 2

10 136 2

10 163 2

10 185 2

10 208 2

10 230 2

10 255 2

10 283 2

10 307 2

10 332 2

10 366 2

10 400 2

10 430 2

10 462 2

10 492 2

10 524 2

10 553 2

10 581 2

10 601 2

615 2

0.1 1.0 10.0 100.0

0.1 1.0 10.0 100.0

D E

P T

H in

CBR

D E

P T

H m m

0 2000 4000 6000 8000 10000

D E

P T

H in

BEARING CAPACITY, psf

Based on approximate interrelationships of CBR and Bearing values (Design of Concrete Airport Pavement, Portland

Cement Association, page 8, 1955)

10.1 lbs.

17.6 lbs.

Both hammers used

Soil Type

CH

CL

All other soils

Hammer

[2 I

[ 0

I

II

h c, IL r, ' L_

L...,__ r-

-:J I :J --,, I

DCP 3 TEST DATA

File Name: South TH Parking Lot, west half

Project: Crown Point Trail Date: 11-Sep-23 Location: South TH wet pumping surface Soil Type(s): Type in the soil type

No. of Accumulative Type of Blows Penetration Hammer

(mm)

10 75 2

10 138 2

10 183 2

10 223 2

10 266 2

10 317 2

10 365 2

10 414 2

10 447 2

10 464 2

10 472 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

0.1 1.0 10.0 100.0

0.1 1.0 10.0 100.0

D E

P T

H in

CBR

D E

P T

H m m

0 2000 4000 6000 8000 10000

D E

P T

H in

BEARING CAPACITY, psf

Based on approximate interrelationships of CBR and Bearing values (Design of Concrete Airport Pavement, Portland

Cement Association, page 8, 1955)

10.1 lbs.

17.6 lbs.

Both hammers used

Soil Type

CH

CL

All other soils

Hammer

[2

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I

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DCP 4 TEST DATA

File Name: ThruCut#1

Project: Crown Point Trail Date: 12-Sep-23 Location: Basalt Thru Cut #1 Soil Type(s): Type in the soil type

No. of Accumulative Type of Blows Penetration Hammer

(mm)

10 105 2

10 226 2

10 237 2

10 244 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

0.1 1.0 10.0 100.0

0.1 1.0 10.0 100.0

D E

P T

H in

CBR

D E

P T

H m m

0 2000 4000 6000 8000 10000 12000

D E

P T

H in

BEARING CAPACITY, psf

Based on approximate interrelationships of CBR and Bearing values (Design of Concrete Airport Pavement, Portland

Cement Association, page 8, 1955)

10.1 lbs.

17.6 lbs.

Both hammers used

Soil Type

CH

CL

All other soils

Hammer

[2 I

[ 0

I

II

I

DCP 5 TEST DATA

File Name: ThruCut#2

Project: Crown Point Trail Date: 12-Sep-23 Location: Basalt Thru Cut #2 Soil Type(s): Type in the soil type

No. of Accumulative Type of Blows Penetration Hammer

(mm)

10 78 2

10 123 2

10 236 2

10 359 2

10 419 2

10 435 2

10 441 2

10 447 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

10 2

0.1 1.0 10.0 100.0

0.1 1.0 10.0 100.0

D E

P T

H in

CBR

D E

P T

H m m

0 2000 4000 6000 8000 10000 12000

D E

P T

H in

BEARING CAPACITY, psf

Based on approximate interrelationships of CBR and Bearing values (Design of Concrete Airport Pavement, Portland

Cement Association, page 8, 1955)

10.1 lbs.

17.6 lbs.

Both hammers used

Soil Type

CH

CL

All other soils

Hammer

[2

I

I ,/

I

I

I

J

I .

DCP 6 TEST DATA

File Name: RRFillSlope

Date: 12-Sep-23Project: Crown Point Trail Location: Railroad Fill near erosion Soil Type(s): Type in the soil type

No. of Accumulative Type of Blows Penetration Hammer

(mm)

10 91 2

10 160 2

10 235 2

10 310 2

10 386 2

10 465 2

10 552 2

10 663 2

10 764 2

10 835 2

10 890 2

10 931 2

10 974 2

10 1019 2

10 1065 2

10 1111 2

10 2

10 2

10 2

10 2

10 2

0.1 1.0 10.0 100.0

0.1 1.0 10.0 100.0

D E

P T

H in

CBR

D E

P T

H m m

0 1000 2000 3000 4000 5000 6000

D E

P T

H in

BEARING CAPACITY, psf

Based on approximate interrelationships of CBR and Bearing values (Design of Concrete Airport Pavement, Portland

Cement Association, page 8, 1955)

10.1 lbs.

17.6 lbs.

Both hammers used

Soil Type

CH

CL

All other soils

Hammer

[2

I

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I J r J

L

I

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I

I I I I

DCP 7 TEST DATA

File Name:

Project: Crown Point Trail Date: 12-Sep-23 Location: North Trailhead @ JH#1001 Soil Type(s): Type in the soil type

No. of Accumulative Type of Blows Penetration Hammer

(mm)

10 118 2

10 187 2

10 217 2

10 243 2

10 261 2

10 284 2

10 310 2

10 342 2

10 381 2

10 436 2

10 515 2

10 631 2

10 787 2

10 966 2

10 1114 2

10 1180 2

0.1 1.0 10.0 100.0

0.1 1.0 10.0 100.0

D E

P T

H in

CBR

D E

P T

H m m

0 2000 4000 6000 8000 10000

D E

P T

H in

BEARING CAPACITY, psf

Based on approximate interrelationships of CBR and Bearing values (Design of Concrete Airport Pavement, Portland

Cement Association, page 8, 1955)

10.1 lbs.

17.6 lbs.

Both hammers used

Soil Type

CH

CL

All other soils

Hammer

[2

I

I ,/

I h_

Ju i -

I

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