Attachment_4_Soils_Evaluation_Report_12-10-18.pdf

LOG CABIN WASTEWATER TREATMENT SYSTEM REHABILITATION

Condition Assessment Report

HECO Engineers i OLYM PMIS No. 229063

TABLE OF CONTENTS

INTRODUCTION

SITE CONDITIONS

Supporting Information Initial Site Exploration 2017 Soil Conditions 2017 Groundwater 2017 Additional Site Exploration 2018 Additional Soil Conditions 2018 Additional Groundwater 2018

CONCLUSIONS

LIST OF FIGURES

Figure 1 Site Plan Figure 2 Location of Test Pits Figure 3 Local Topography Figure 4 Log of Test Pits Figure 5 Log of Test Pits Figure 6 Log of Test Pits Figure 7 Log of Test Pits Figure 8 Log of Test Pits Figure 9 Log of Test Pits Figure 10 Log of Test Pits

ATTACHMENTS

ATTACHMENT A Laboratory Test Results

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HECO Engineers 1 OLYM PMIS No. 229063

INTRODUCTION

Plans for the original treatment system began in 1979 with preliminary surveys completed by the Denver Service Center. The sewage collection and treatment systems were installed in 1981-82 and consist of a gravity collection system of PVC sewer line, manholes, and cleanouts consolidating flow from cabins and buildings at the centralized 16,000-gallon septic tank and 20,000-gallon storage tanks. A pump chamber located at the end of the gravity-flow septic and storage tanks sends effluent in a 4-inch pressurized line approximately 2,000 feet to the sand filter mound site near East Beach Road. A schematic of the sewer collection system and location of septic and lift station is seen in Figure 1.

In the fall of 1982, seepage along the south toe of the mound prompted the installation of collection drains around the west, south, and east slopes of the mound, with collected effluent from the mound piped to a secondary drain field constructed for disposal downslope and adjacent to Log Cabin Creek. In 1985, emergency corrective actions were completed to improve aeration to the mound, which was constructed with improperly graded (too fine) sand fill resulting in liquid buildup. The mound system corrections did not improve the use of it, and it was deemed to have failed shortly thereafter.

In 1986, the septic and storage tanks were converted to provide primary sedimentation and flow equalization, and effluent was pumped to a newly installed Sanilogical (now Santec®) Corporation biological treatment plant with provisions for disinfection. This buried treatment facility is located directly adjacent to the original mound disposal area, which was abandoned at the time in lieu of a new dosing siphon and valving system, allowing effluent disposal to alternate between the existing drain field and a new drain field, located upslope of the original drain field near Log Cabin Creek.

The new 4-inch perforated pipe drain field was installed about 360 feet southeast of the treatment plant site. This primary drain field replaced the mound drain field system which was no longer functioning as designed. The design of this new drain field system called for a total of five parallel perforated pipes measured at 110 feet long each positioned in an area about 20 feet wide according to the 1986 construction plan documents.

In mid-September of 2014, the NPS conducted a Public Health Survey of the Log Cabin facility and identified deficiencies in this system that could result in public health hazards. Some of the identified deficiencies included failing components, maintenance and operation concerns of the buried treatment system and tank deterioration, a lack of backup generator, lack of tertiary

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HECO Engineers 2 OLYM PMIS No. 229063 filtration, lack of a flowmeter, poor sludge holding and removal capabilities, insufficient sizing of the effluent drain field and increased visitation in the Log Cabin area.

Subsequent to this survey, we understand that the treatment plant is being considered for replacement with a new system including treatment and disposal capabilities. HECO Engineers (HECO) was then contracted to develop options for the replacement systems. While there is sufficient area adjacent to the existing treatment system for siting a new system, a suitable site for the disposal option needed to be identified. The purpose of this soils evaluation is to investigate other sites which might be usable for a new disposal option consisting of a large drain field. Two areas were identified as possible locations for use, one in the vicinity of the failed mound disposal system and the other an open area north of the current treatment site between the East Beach Road and the site’s drinking water storage tank.

The initial site exploration, conducted on 10/3/17, encountered unsuitable soil conditions between East Beach Road and the site’s drinking water storage tank. Two test pits near the south edge of the failed mound system encountered suitable soils. However, HECO was unable to excavate sufficient test pits in this area to confirm the extent of the suitable soils because environmental compliance had not been obtained to excavate additional test pits in this vicinity.

Additional explorations were authorized in mid-2018, but excavation could not start until October because of the potential for disturbing nesting birds. This revised report will then summarize the new excavations supplementing the originals and the assessment of the best locations for a disposal drainfield.

SITE CONDITIONS

Supporting Information

The NRCS map and soil survey database was searched, but no map was found for this area. Calls to the nearest NRCS field office confirmed that no soil survey maps were available for this area.

Initial Site Exploration 2017

The weather was sunny and cool during the site explorations. Subsurface conditions at the Log Cabins Resort site were explored to depths ranging from approximately 1.7 to 9.5 feet below existing ground surface (bgs) by excavating eight test pits on October 3, 2017, at the approximate locations shown in Test Pit Locations, Figure 2. The test pits were excavated with a mini-excavator owned and operated by the NPS.

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HECO Engineers 3 OLYM PMIS No. 229063

A HECO geotechnical engineer from the Payette, Idaho office observed the explorations on a full-time basis, maintained detailed logs, and obtained representative samples of the soils encountered for further examination. The soils encountered were classified visually in accordance with the USDA Textural Classification Chart as shown in Attachment A. The logs of the test pits are shown in Figures 4 through 6. The disturbed soil samples were further evaluated by American Geotechnics' laboratory to evaluate grain-size and confirm soil classifications. The results of these tests are presented in Attachment A.

Soil Conditions 2017

Test pit TP-1 was excavated into the toe of the existing abandoned mound system to observe the soil within the failed mound system and the native soil beneath the mound system. The soils exposed in the edge of the mound system consisted only of the clay cap material which covers the interior sand and distribution system. This information was not recorded on the log. The depths shown are measured from the native ground surface. The native soils observed from the ground surface to a depth of approximately 7.5 feet below ground surface (bgs) consisted of reddish brown extremely gravelly loamy coarse sand to coarse sand. The color was uniform with no mottling. The silt and clay content varied slightly as demonstrated by the test results at 0.5 and 2.0 feet. From approximately 7.5 to 9.5 feet bgs, grayish brown extremely gravelly sand was observed which was moist and medium dense. No groundwater seepage was observed in this test pit. However, the soil color change below 7.5 feet suggests that this might represent the seasonal high groundwater level.

The ground surface south of the existing mound system was explored by scraping through the forest duff to expose the surficial soils. These soils appeared to be gravelly loamy sand for approximately 200 feet west of the gravel access road along the east side of the existing mound system, and for at least 100 feet south of the existing mound system. Test pit TP-8 was excavated between the trees south of the abandoned mound system within approximately 100 feet from TP-1. We observed extremely gravelly fine sandy loam from the ground surface to a depth of approximately 0.8 feet bgs. From 0.8 feet to approximately 6.0 feet bgs, we observed brown extremely gravelly loamy sand. From 6.0 feet to the bottom of the exploration at approximately

8.1 feet bgs, we observed brown extremely gravelly loamy sand with significantly less silt and clay than observed above 6.0 feet. The color of the soil layers was uniform without any suggestion of mottling or other color change which might suggest a seasonal high groundwater table.

Test pits TP-2 and TP-3 were excavated near the northwest corner of the abandoned mound system in an attempt to understand why it failed. TP-2 was excavated just outside the toe of the

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HECO Engineers 4 OLYM PMIS No. 229063 mound system. A silty clay loam from the ground surface to a depth of approximately 1.9 feet bgs was observed. From 1.9 feet to approximately 2.9 feet, a stiff blocky brown silty clay was observed. Below 2.9 feet to the bottom of the exploration at approximately 5.2 feet, a dark gray highly fractured rock was observed. No groundwater seepage was observed within this test pit.

Test pit TP-3 was excavated through the abandoned mound system. The materials observed included the clay cap at the ground surface over a layer of non-woven geotextile placed to protect the underlying drain rock. Native soil consisting of sandy clay loam was observed below the sand at a depth of approximately 7.0 feet bgs. No groundwater seepage was observed; however, mottling was present at a depth of approximately 8.5 feet bgs, which suggests that this might be the seasonal high groundwater level.

Test pits TP-4 through TP-7 were excavated northeast of the abandoned mound system, below the water tank for the facility (see Figure 2). This is within a cleared area which appears to be a remnant of an old residence with some fruit trees and rose bushes present within the area.

Several wetlands were noted to be scattered throughout this cleared area. In TP-4, a thin sod and root zone to a depth of approximately 0.2 feet bgs was observed. Below the sod to a depth of approximately 3.7 feet bgs, a brown fine sandy clay loam was observed. From 3.7 to approximately 4.1 feet bgs, a grayish brown mottled fine sandy clay loam was observed. Below

4.1 feet to the bottom of the exploration at approximately 5.3 feet bgs, a grayish brown mottled very stiff, blocky, silty clay was observed. No groundwater seepage was observed in this test pit;

however, the mottling at and below 3.7 feet bgs appears to represent the seasonal high groundwater table. In TP-5 and TP-7, brown loam below the sod to depths of approximately 3.3 to 4.0 feet was observed. Below these depths mottling which suggests seasonal high groundwater was observed. The mottled soils observed were silty clay and clay loam respectively. Brown silty clay loam in TP-6 from the sod to a depth of approximately 0.7 feet bgs was observed. Mottled gray and brown silty clay loam was observed from 0.7 feet to the bottom of the exploration at a depth of approximately 1.7 feet. We estimate the seasonal high groundwater to be at a depth of approximately 0.7 feet at this location.

Groundwater 2017

No groundwater seepage was observed in any of the test pits. The surface of the native soil encountered below the abandoned mound system in test pit TP-3 had a significantly higher moisture content than surficial native soils encountered in any other test pit, including TP-1, which was also excavated through the abandoned mound system. Groundwater will vary as a function of season, precipitation, and other factors.

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HECO Engineers 5 OLYM PMIS No. 229063

Additional Site Exploration 2018

Additional test pits were excavated in the area south of the failed mound system on October 3, 2018 using a track-mounted mini-excavator owned and operated by the NPS. These test pits are designated Test Pit 1a through Test Pit 11a, and the locations of these test pits are shown in Figure 3a. Test Pit 12a was excavated adjacent to the existing lower drain field to evaluate the soil conditions at that location. The logs of these explorations are presented in Figures 7, 8, 9, and 10.

Additional Soil Conditions 2018

Test pits TP-1 and TP-8 from the initial site exploration (Figure 3a) encountered soils suitable for a large drain field. The soils encountered in these test pits are described in the “Soil Conditions 2017” section above. Test Pits TP-2a, TP-3a, TP-6a, and TP-9a encountered soil horizons which were too thin to support a large drain field as the soils were less than 1.5 feet thick over weathered bedrock. Test pit TP-7a encountered approximately 2.2 feet of silt loam over bedrock.

However, this silt loam exhibited little apparent structure, and does not appear suitable for a large drain field. Test pit TP-10a encountered approximately 1.2 feet of silt loam over clay and bedrock. This soil does not appear suitable for a large drain field.

Test pits TP-1a, TP-4a, TP-5a, TP-8a, and TP-11a encountered sufficient depth of soils to support a large drain field. In TP-1a, we observed very gravelly sandy loam from the ground surface to a depth of approximately 1.5 feet. From 1.5 feet to the bottom of the exploration at 6.3 feet, we observed extremely gravelly medium loamy sand. In TP-4a, we observed very gravelly sandy loam from the ground surface to a depth of approximately 1.8 feet. From 1.8 feet to the bottom of the exploration at approximately 4.3 feet, we observed highly weathered bedrock. The surface of the rock was sloping steeply downward toward the location of TP-1a (Figure 3a). In TP-5a, we observed loam with fine sand from the ground surface to a depth of approximately 3.0 feet. From

3.0 feet to the bottom of the exploration at approximately 4.3 feet, we observed medium sandy loam. In test pit TP-8a, we observed fine sandy loam from the ground surface to a depth of approximately 1.3 feet. This material appeared to be fill from construction of the adjacent mound system. From 1.3 feet to approximately 3.3 feet, we observed extremely gravelly medium to coarse sandy loam. From 3.3 feet to the bottom of the exploration at approximately 6.2 feet, we observed very gravelly loamy sand. In TP-11a, we observed gravelly loam from the ground surface to a depth of approximately 2.2 feet. From 2.2 feet to approximately 2.8 feet, we observed very gravelly loam. From 2.8 feet to the bottom of the exploration at approximately

4.0 feet, we observed a stiff silt with a trace of fine sand. No groundwater seepage was observed

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HECO Engineers 6 OLYM PMIS No. 229063 in any of the test pits listed above. No mottling or other discoloration which might suggest seasonally saturated soils was observed.

TP-12a was excavated adjacent to the existing lower drain field. We observed gravelly loam with fine to coarse sand from the ground surface to a depth of 1.3 feet. Below 1.3 feet to the bottom of the exploration at approximately 6.5 feet, we observed extremely gravelly loamy medium to coarse sand. No indications of groundwater were observed.

Additional Groundwater 2018

No groundwater seepage was observed in any of the additional 2018 test pits. No soil discoloration suggesting seasonal saturation was observed in any of the 2018 test pits.

Groundwater will vary as a function of season, precipitation, and other factors.

CONCLUSIONS

The western edge of the existing mound system appears to be underlain by a low permeability silty clay loam or silty clay with a shallow seasonal high groundwater table. The southeastern part of the mound system appears to be on sand. The division between these soil types was not observed. The sand placed for the treatment zone in the mound system was finer than expected.

It is our opinion that these two factors contributed to the failure of the system.

In our opinion, the cleared area below the existing water tank is not suitable for a large drain field. Scattered wetlands are present throughout the cleared area, the soils observed in our test pits TP-4 to TP-7 (see Figure 2), range from Type 4 to Type 7, and the location with the Type 4 soil slopes steeply to the south.

The soils observed in test pits TP-1, TP-8, TP-1a, TP-4a, TP-5a, TP-8a, and TP-11a (see Figure 3a) encountered soils of sufficient quality and thickness to support a large drain field. Soils range from Type 1 to Type 4 in these test pits. The ground surface is moderately sloping, and the seasonal high groundwater elevation appears to be at least 7.5 feet below the existing ground surface (test pit TP-1). This area will require significant tree and brush removal.

One test pit, TP-12a, was excavated adjacent the existing lower drain field (Figure 3a). The native soils observed were extremely gravelly loamy sand with no indications of saturated seasonal conditions to the depth explored (6.5 feet). The soils at this location are conducive to drain field use.

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Local Topography, Figure 3

To Water Tank

Test Pit Location, Figure 2

Site Plan, Figure 1

SOILS EVALUATION

Existing Test Pit Locations, Figure 2

TP-2

TP-1

TP-3

TP-8

To TPs 4 -7

Additional Test Pit Locations, Figure 3a TP-12a

TP-2a

TP-1a

TP-8a

TP-7a

TP-3a

TP-6a

TP-9a

TP-11a TP-10a

TP-4a

TP-5a

Approximate Limit of Suitable Soils for LOSS

LOG OF TEST PITS

Equipment: Rubber-tracked mini-excavator Observer: DEA

Operator NPS Date: October 3, 2017 Depth Below

Ground Surface (feet)

Soil Texture

Classification Description

HECO Engineers 10 OLYM PMIS No. 229063

TEST PIT 1

Weather: Sunny, Cool

0 – 7.5 Loamy Sand/Sand Reddish brown extremely gravelly loamy coarse sand to coarse sand, moist, medium dense

7.5 – 9.5 Sand Grayish brown extremely gravelly sand, moist, medium dense

Test pit completed at 9.5 feet on 10/3/17.

Minor caving from 0 to 9.5 feet No groundwater seepage observed Disturbed samples obtained at 0.5 and 2.0 feet Apparent seasonal high groundwater at 7.5 feet

TEST PIT 2

Weather: Sunny, Cool

0 – 1.9 Silty Clay Loam Light brown silty clay loam with fine roots, moist, stiff

1.9 – 2.9 Silty Clay Brown silty clay, blocky, moist, stiff

2.9 – 5.2 Rock Dark gray highly fractured rock

Test pit completed at 5.2 feet on 10/3/17 No caving observed No groundwater seepage observed Disturbed soil samples obtained at 1.7 and 2.4 feet

TEST PIT 3

Weather: Sunny, Cool

0 – 2.7 Clay Dark brown silty clay, moist, stiff, fill (clay cap) over abandoned drain field

2.7 – 3.8 Rock Light gray 0.6 to 1.0-inch drain rock for abandoned drain field

3.8 – 7.0 Sand Brown medium sand, moist, medium dense, fill, treatment material for abandoned drain field

7.0 – 9.0 Sandy Clay Loam Dark gray fine sandy clay loam with occasional gravel, wet, native soil. Mottling present at 8.5 feet.

Test pit complete at 9 feet on 10/3/17 Caving observed between 2.7 and 3.8 feet No groundwater seepage observed Disturbed soil samples obtained at 4.0 and 9.0 feet Apparent seasonal high groundwater at 8.5 feet

FIGURE 4 – Log of Test Pits

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mini-excavator Observer: DEA

Operator NPS Date: October 3, 2017 Depth Below

Ground Surface (feet)

Soil Texture

Classification Description

HECO Engineers 11 OLYM PMIS No. 229063

TEST PIT 4

Weather: Sunny, Cool

0 – 0.2 Sod

0.2 – 3.7 Sandy Clay Loam Brown fine sandy clay loam with fine roots, occasional gravel and boulders, moist, stiff

3.7 – 4.1 Sandy Clay Loam Grayish brown mottled fine sandy clay loam, moist, stiff

4.1 – 5.3 Silty Clay Grayish brown mottled silty clay, blocky, hard, moist

Test pit complete at 5.3 feet on 10/3/17 No caving observed No groundwater seepage observed Disturbed soil samples obtained at 1.1, 2.1, & 3.9 feet Apparent seasonal high water at 3.7 feet

TEST PIT 5

Weather: Sunny, Cool

0 – 0.2 Sod

0.2 – 3.3 Loam Brown loam, moist, stiff

3.3 – 4.0 Loam Grayish brown mottled loam, moist, stiff

4.0 – 5.2 Silty Clay Grayish brown mottled silty clay, blocky, hard, moist

Test pit complete at 5.2 feet on 10/3/17 No caving observed No groundwater seepage observed Disturbed soil samples obtained at 1.5, 3.0, and 3.7 feet Apparently seasonal high groundwater at 3.3 feet

TEST PIT 6

Weather: Sunny, Cool

0 – 0.2 Sod

0.2 – 0.7 Silty Clay Loam Brown silty clay loam, moist, stiff

0.7 – 1.7 Silty Clay Loam Grayish brown mottled silty clay loam (very stiff, moist)

Test pit completed at 1.7 feet on 10/3/17 No caving observed No groundwater seepage observed No samples obtained Apparent seasonal high groundwater at 0.7 feet

FIGURE 5 – Log of Test Pits

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mini-excavator Observer: DEA

Operator NPS Date: October 3, 2017 Depth Below

Ground Surface (feet)

Soil Texture

Classification

Description

HECO Engineers 12 OLYM PMIS No. 229063

TEST PIT 7

Weather: Sunny, Cool

0 – 0.2 Sod

0.2 – 0.5 Loam Brown loam, moist, stiff

0.5 – 4.0 Loam Light brown loam, moist, stiff

4.0 – 4.3 Clay Loam Brown and gray mottled clay loam, moist, stiff

Test pit complete at 4.3 feet on 10/3/17 No caving observed No groundwater seepage observed Disturbed samples obtained at 0.4, 2.5, and 4.2 feet Apparent seasonal high groundwater at 4.0 feet

TEST PIT 8

Weather: Sunny, Cool

0 – 0.8 Sandy Loam Brown extremely gravelly fine sandy loam, moist, medium stiff

0.8 – 6.0 Loamy Sand Brown extremely gravelly loamy sand, moist, medium dense

6.0 – 8.1 Loamy Sand Brown extremely gravelly loamy sand, moist, medium dense (notably less silt than soil above)

Test pit complete at 8.1 feet on 10/3/17 Minor caving observed below 1 foot No groundwater seepage observed Disturbed samples obtained at 0.5, 4.9, and 7.0 feet No apparent seasonal high groundwater indicators observed

FIGURE 6 – Log of Test Pits

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mini-excavator Observer: DEA

Operator NPS Date: October 3, 2018 Depth Below

Ground Surface (feet)

Soil Texture

Classification Description

HECO Engineers 13 OLYM PMIS No. 229063

TEST PIT 1a 0 – 1.5 Sandy Loam Brown very gravelly fine to medium sandy loam with fine roots (loose to medium dense, moist)

1.5 – 6.3 Loamy Sand Light brown extremely gravelly medium loamy sand (medium dense, moist)

Test pit completed at 6.3 feet on 10/3/18 No caving observed No groundwater seepage observed Disturbed samples obtained at 0.8 and 3.0 feet No seasonal high groundwater indicators observed

TEST PIT 2a 0 – 0.5 Loam Dark brown loam with roots and organic matter (loose, moist)

0.5 – 2.0 Rock Light brown highly weathered bedrock (dense, moist)

Test pit completed at 2.0 feet on 10/3/18 No caving observed No groundwater seepage observed No soil samples obtained No seasonal high groundwater indicators observed

TEST PIT 3a 0 - 0.7 Silt Loam Dark brown gravelly silt loam with fine to medium sand and roots (loose, moist)

0.7 – 1.3 Sandy Loam Light brown very gravelly fine sandy loam with roots (medium dense, moist)

1.3 – 2.5 Rock Brown highly weathered bedrock (dense, moist)

Test pit complete at 2.5 feet on 10/3/18 No caving observed No groundwater seepage observed No soil samples obtained No seasonal high groundwater indicators observed

FIGURE 7 – Log of Test Pits

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mini-excavator Observer: DEA

Operator NPS Date: October 3, 2018 Depth Below

Ground Surface (feet)

Soil

HECO Engineers 14 OLYM PMIS No. 229063

TEST PIT 4a

0 – 1.8 Sandy Loam Brown very gravelly fine to medium sandy loam (loose to medium dense, moist)

1.8 – 4.3 Rock Light brown highly weathered bedrock (dense, moist) (note: sloping contact. Rock surface sloping down toward Test Pit-1a)

Test pit complete at 4.3 feet on 10/3/18 No caving observed No groundwater seepage observed Disturbed soil sample obtained at 1.2 feet No seasonal high groundwater indicators observed

TEST PIT 5a 0 – 3.0 Loam Brown loam with fine sand, occasional gravel, and fine roots to a depth of 2 feet (loose to medium dense, moist)

3.0 – 4.3 Sandy Loam Light brown medium sandy loam with occasional gravel (medium dense, moist)

Test pit complete at 4.3 feet on 10/3/18 No caving observed No groundwater seepage observed Disturbed soil samples obtained at 2.0 and 4.0 feet

TEST PIT 6a

0 – 1.1 Loam Brown extremely gravelly loam with fine sand (loose, moist)

1.1 – 1.3 Rock Light brown highly weathered rock (dense, moist)

Test pit completed at 1.3 feet on 10/3/18 No caving observed No groundwater seepage observed No soil samples obtained

FIGURE 8 – Log of Test Pits

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mini-excavator Observer: DEA

Operator NPS Date: October 3, 2018 Depth Below

Ground Surface (feet)

Soil Texture

Classification Description

HECO Engineers 15 OLYM PMIS No. 229063

TEST PIT 7a

0 – 2.2 Silt Loam Light brown gravelly silt loam with fine sand (loose to medium dense, moist)

Test pit complete at 2.2 feet on 10/3/18 No caving observed No groundwater seepage observed No samples obtained No seasonal high groundwater indicators observed

TEST PIT 8a

0 – 1.3 Sandy Loam Brown fine sandy loam with roots (medium dense, moist) (fill from mound system)

1.3 – 3.3 Sandy Loam Brown extremely gravelly medium to coarse sandy loam (medium dense to dense, moist)

3.3 – 6.2 Loamy Sand Brown very gravelly fine to coarse loamy sand (dense, moist)

Test pit complete at 6.2 feet on 10/3/18 No caving observed No groundwater seepage observed Disturbed soil samples obtained at 0.7, 2.0, and 4.3 feet No seasonal high groundwater indicators observed

TEST PIT 9a

0 – 1.3 Sandy Loam Brown gravelly fine sandy loam with roots (loose to medium dense, moist)

1.3 – 3.7 Rock Light brown highly weathered bedrock (dense, moist)

Test pit complete at 3.7 feet on 10/3/18 No caving observed No groundwater seepage observed No soil samples obtained No seasonal high groundwater indicators observed

FIGURE 9 – Log of Test Pits

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mini-excavator Observer: DEA

Operator NPS Date: October 3, 2018 Depth Below

Ground Surface (feet)

Soil

HECO Engineers 16 OLYM PMIS No. 229063

TEST PIT 10a

0 – 1.2 Silt Loam Brown very gravelly silt loam with fine sand (medium dense, moist)

1.2 – 3.0 Clay Light brown clay with silt (stiff, moist)

3.0 – 3.5 Rock Light brown highly weathered bedrock (dense, moist)

Test pit complete at 3.5 feet on 10/3/18 No caving observed No groundwater seepage observed Disturbed soil sample obtained at 0.8 feet

TEST PIT 11a

0 – 2.2 Loam Brown gravelly loam with medium to coarse sand (medium dense, moist)

2.2 – 2.8 Loam Light brown very gravelly loam with medium sand (dense, moist)

2.8 – 4.0 Silt Light brown gravelly silt with a trace of fine sand (stiff, moist)

Test pit completed at 4.0 feet on 10/3/18 No caving observed No groundwater seepage observed Disturbed soil sample obtained at 1.3 feet

TEST PIT 12a

0 – 1.3 Loam Brown gravelly loam with fine to coarse sand and roots (medium dense, moist) (fill from adjacent drain field construction)

1.3 – 6.5 Loamy Sand Brown extremely gravelly loamy medium to coarse sand (medium dense to dense, moist)

Test pit complete at 6.5 feet on 10/3/18 No caving observed No groundwater seepage observed Disturbed soil samples obtained at 0.7, 3.0, and 6.0 feet

FIGURE 10 – Log of Test Pits

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HECO Engineers ATTACHMENT A OLYM PMIS No. 229063

ATTACHMENT A

LABORATORY TEST RESULTS

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19.8 23.0

53.0 45.0

27.2 32.0

SANDY LOAM

SANDY LOAM

LOAM

SANDY LOAM

Olympic National Park

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LOAM

LOAMY SAND

Olympic National Park

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Olympic National Park

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