Saddle_Road_East_Side.Draft_Geotechnical_Data_Report_(1).pdf

GEOTECHNICAL DATA REPORT

HAWAII STATE ROUTE 200 (SADDLE ROAD)

MILEPOST 11 TO MILEPOST 5.6

(SADDLE ROAD EAST SIDE)

ISLAND OF HAWAII

W.O. 4984‐30 & 40 JULY 2, 2015

Prepared for

OKAHARA & ASSOCIATES, INC.

and

FEDERAL HIGHWAY ADMINISTRATION

CENTRAL FEDERAL LANDS

HIGHWAY DIVISION

GEOLABS, INC.

Geotechnical Engineering and Drilling Services

DRAFT - Pre-Final Design Submittal - 07/02/2015

MILEPOST 11 TO MILEPOST 5.6

(SADDLE ROAD EAST SIDE)

W.O. 4984-30 & 40 JULY 2, 2015

Prepared for

OKAHARA & ASSOCIATES, INC.

and

FEDERAL HIGHWAY ADMINISTRATION

CENTRAL FEDERAL LANDS

HIGHWAY DIVISION

THIS WORK WAS PREPARED BY

ME OR UNDER MY SUPERVISION.

4-30-12

SIGNATURE EXPIRATION DATE

OF THE LICENSE

2006 Kalihi Street • Honolulu, HI 96819

2006 Kalihi Street • Honolulu, Hawaii 96819

Phone: (808) 841-5064 • Facsimile: (808) 847-1749 • E-mail: hawaii@geolabs.net

Hawaii • California

July 2, 2015 W.O. 4984-30 & 40

Mr. Bruce Meyers, P.E.

Okahara & Associates, Inc.

200 Kohola Street Hilo, HI 96720

Dear Mr. Meyers:

This geotechnical data report (GDR) presents the results of our field exploration and laboratory test program performed for the Hawaii State Route 200 (Saddle Road), Milepost 11 to Milepost 5.6 (Saddle Road East Side) project on the Island of Hawaii in support of the design of the project.

Our work was performed in general accordance with the scope of services outlined in our fee proposals dated June 29 and September 8, 2009. The scope of services generally was based on the tasks outlined in Task Order Nos. DTFH68-07- T00001 and DTFH68-05-D3-T-09-003 and Scope of Work documents dated July 21 and August 12, 2009 and subsequent modifications.

If you have questions or need additional information, please contact our office.

Very truly yours, Robin M. Lim, P.E.

Vice President

RML:TK:asn

MILEPOST 11 TO MILEPOST 5.6

(SADDLE ROAD EAST SIDE)

W.O. 4984-30 & 40 GEOLABS, INC. Page i

TABLE OF CONTENTS

Page

1. PROJECT CONSIDERATIONS

2. SCOPE OF WORK

3. SITE CHARACTERIZATION

3.1 Regional Geology

3.2 Local Site Geology

3.3 General Site Conditions

3.4 Climate

3.5 Geologic Materials

3.5.1 Geologic Material Type No. 1

3.5.2 Geologic Material Type No. 2

3.5.3 Geologic Material Type No. 3

3.5.4 Geologic Material Type No. 4

3.6 Existing Site Conditions

3.6.1 Station 1545+00 to Station 1696+00

3.6.2 Station 1696+00 to Station 1721+00

3.6.3 Station 1721+00 to Station 1742+00

3.6.4 Station 1742+00 to Station 1766+50

3.6.5 Station 1766+50 to Station 1771+50

3.6.6 Station 1771+50 to Station 1776+50

3.6.7 Station 1776+50 to Station 1793+20

3.6.8 Station 1793+20 to Station 1850+50

3.6.9 Station 1850+50 to Station 1858+00

3.6.10 Summary

4. GEOTECHNICAL EXPLORATION PROGRAM

4.1 Test Borings

4.2 Hand Probing

4.3 Geophysical Investigations

4.4 Laboratory Testing

5. LIMITATIONS

CLOSURE

REFERENCES

MILEPOST 11 TO MILEPOST 5.6

(SADDLE ROAD EAST SIDE)

W.O. 4984-30 & 40 GEOLABS, INC. Page ii

PLATES

Project Location Map ................................................................................... Plate 1 Overall Site Plan .......................................................................................... Plate 2 Site Plans ............................................................................... Plates 3.1 thru 3.11 Geology Map ............................................................................................... Plate 4

APPENDIX A

Test Boring Exploration ........................................................... Pages A-1 and A-2 Approximate Boring Locations ........................................... Tables A-1.1 and A-1.2 Permits to Work within the County Right-of-Way ................................... Figure A-1 Soil Log Legend .................................................................................... Plate A-0.1 Soil Classification Log Key ................................................................... Plate A-0.2 Rock Log Legend ................................................................................. Plate A-0.3 Logs of Borings ...................................................................... Plates A-1 thru A-47

APPENDIX B

Hand Probing Exploration ....................................................................... Page B-1 Summary of Hand Probing Results ................................... Tables B-1.1 and B-1.2

APPENDIX C

Refraction MicroTremor Survey

APPENDIX D

Laboratory Tests ..................................................................................... Page D-1 Summary of Index Property Test Results ......................... Tables D-1.1 thru D-1.4 Summary of Strength Test Results ......................................................... Table D-2 Laboratory Test Data ............................................................. Plates D-1 thru D-40

APPENDIX E

Photographs of Core Samples ............................................... Plates E-1 thru E-53

APPENDIX F

Photographs of Field Exploration ........................................... Plates F-1 thru F-47

APPENDIX G

Selected Data from 2003 Geotechnical Engineering Exploration

W.O. 4984-30 & 40 GEOLABS, INC. Page 1

SECTION 1. PROJECT CONSIDERATIONS

The existing Hawaii State Route 200 (Saddle Road) extends from the eastern terminus at about Milepost (MP) 5.6 west of Hilo to the western terminus at its intersection with Hawaii State Route 190 (Mamalahoa Highway) on the Island of Hawaii.

This geotechnical data report presents the results of our field exploration and laboratory tests performed for the portion of new Saddle Road within the approximate limits between Milepost 11 and Milepost 5.6. The project location and general vicinity are shown on the Project Location Map, Plate 1.

A summary of the field exploration program conducted for the afore-mentioned segment of Saddle Road is presented below. Detailed information and discussions for each specific work item are provided in the respective appendices of this geotechnical data report.

TABLE 1

SUMMARY OF FIELD EXPLORATION PROGRAM

Work Item Location Description Appendix

Test Boring Exploration

B-201 thru B-247

Drilling/Coring and sampling at 47 test boring locations extending to depths ranging from about 15 to

39 feet each for a total of about 1,046 lineal feet of exploration

A

Hand Probing Exploration

HP-01 thru HP-45 Hand probing with a 0.5-inch diameter, 3-foot long steel rod at 45 selected locations

B

Refraction MicroTremor

Survey

ReMi Line 1 thru ReMi Line 4

Performance of Refraction MicroTremor (ReMi) survey at four selected locations C

The approximate test boring locations are shown on the Overall Site Plan, Plate 2. Detailed field investigative locations are presented on the Site Plans, Plates 3.1 through 3.11.

END OF PROJECT CONSIDERATIONS

W.O. 4984-30 & 40 GEOLABS, INC. Page 2

SECTION 2. SCOPE OF WORK

The purpose of our field exploration and laboratory test program for the project was to perform additional exploration to evaluate the subsurface conditions at the project site in support of the design of the project. Our work was performed in general accordance with the scope of services outlined in our fee proposals dated June 29 and

September 8, 2009. The scope of services generally was based on the tasks outlined in the Task Order Nos. DTFH68-07-T00001 and DTFH68-05-D3-T-09-003 and Scope of

Work documents dated July 21 and August 12, 2009 and subsequent modifications. In order to accomplish this, we conducted a field exploration and laboratory testing program consisting of the following tasks and efforts:

1. Research and review of available in-house geologic and soils information in the project vicinity and other geotechnical or geological reports that are available for the general project corridor. A list of the references used in the preparation of this geotechnical data report is presented in the reference section.

2. Reconnaissance of the project alignment by our project manager and project geologist to review the existing geotechnical conditions at the site.

3. Preparation and submittal of a field exploration work plan for the subsurface exploration.

4. Coordination with the County of Hawaii – Department of Public Works to obtain the Permit to Work Within the County Right-of-Way for the boring locations within the public right-of-way. A copy of the permit is presented as Figure A-1 in Appendix A.

5. Right-of-entry access to properties beyond the limits of the Saddle Road right-of-way and other special permits to perform work in areas outside of the right-of-way were provided by Okahara & Associates.

6. Stake-out of the boring locations using the available field survey references and existing highway mile markers. Photographs of the boring locations were recorded during the field exploration.

7. Coordination of utility toning and clearance of the boring locations by our geologist.

8. Provision of safety devices for traffic control at selected boring locations during our field exploration program.

SECTION 2. SCOPE OF WORK

W.O. 4984-30 & 40 GEOLABS, INC. Page 3

9. Implementation of best management practices (BMPs) during our field exploration work within the roadway and in other paved areas.

10. Stake-out of the access trails and coordination with our subcontractor to perform leveling of access trails and drilling pads along the project alignment to facilitate the drilling exploration. The access trail clearing work was monitored by our field personnel during the work.

11. Mobilization and demobilization of truck and skid-mounted drilling equipment and operators from Honolulu to the project and back.

12. Rental of a helicopter to assist in the mobilization and demobilization of drilling equipment, supplies, and personnel at 16 boring locations.

13. Rental of a high capacity water truck to assist the core drilling exploration.

14. Drilling/Coring and sampling of 47 borings extending to depths ranging from about 15 to 39 feet below the existing ground/pavement surface along the alignment corridor for a total of about 1,046 lineal feet of exploration.

15. Coordination of the field exploration and logging of the borings by our geologist. Photographs of the rock cores were taken for report presentation.

16. Hand probing with a 0.5-inch diameter, 3-foot long steel rod into the existing ground surface at 45 selected locations to evaluate the vertical extent of volcanic ash deposit by our geologist.

17. Performance of Refraction MicroTremor (ReMi) survey by Zonge Geosciences, Inc. with assistance from Geolabs at four selected locations for a total of four survey lines along the proposed roadway alignment.

18. Laboratory testing of selected soil and rock core samples retrieved during the field exploration as an aid in classifying the materials and evaluating their engineering properties.

19. Preparation of this geotechnical data report presenting the results of the geotechnical data review, subsurface exploration, and laboratory tests.

20. Quality assurance of our overall work and attendance of meetings and consultation with the client/design team by our project manager.

21. Miscellaneous work efforts such as drafting, word processing, and clerical support.

END OF SCOPE OF WORK

W.O. 4984-30 & 40 GEOLABS, INC. Page 4

SECTION 3. SITE CHARACTERIZATION

3.1 Regional Geology

The Hawaiian Archipelago consists of an elongated island chain comprising the eight major islands of the State of Hawaii and hundreds of small islets and atolls extending for more than 1,000 miles to the northwest of the Hawaiian Island of Niihau.

The age of the islands in the Hawaiian Archipelago increases, progressing from the southeast toward the northwest direction.

The Hawaiian Archipelago is believed to have formed as a result of plate tectonic movement working in combination with a relatively deep, stationary focal point of volcanic heat and magma (lava) generation. The Pacific Plate, containing the upper earth’s crust underlying the Central Pacific Ocean, continues to slowly move in a northwesterly direction while the nearly stationary “hot spot” of magma generation continues to produce eruptive emissions beneath the plate. As a result, a continuous chain of volcanic islands formed and has slowly moved off in the northwesterly direction, carried away from the active center of volcanism by plate movement. The Island of

Hawaii is presently located adjacent to the deep-seated “hot spot” region. The most distant volcanic island remnants located far to the northwest of Hawaii have been reduced to submerged seamounts as a result of a long history of land erosion and subsidence.

The Island of Hawaii, the largest and youngest island in the Hawaiian

Archipelago, covers an area of approximately 4,030 square miles. The Island of Hawaii was formed by the coalescence of five primary shield volcano mountains. The five primary shield volcanoes (in decreasing geologic age) include the following:

Kohala (located at the northern tip of the island), which is long extinct

Mauna Kea (located at the northern central portion of the island), which has had some activity during recent geologic time

SECTION 3. SITE CHARACTERIZATION

W.O. 4984-30 & 40 GEOLABS, INC. Page 5

Hualalai (located at the western portion of the island), which last erupted in 1801

Mauna Loa and Kilauea Volcanoes (located at the southern and eastern portions of the island), both of which are still active

Submarine volcanic activity on the Island of Hawaii is believed to have commenced in the late Pliocene and early Pleistocene Epoch (about 1 to 2 million years ago) and continues today with eruptive activity at Kilauea Volcano. It is believed that the

Island of Hawaii breached the ocean surface approximately 500,000 years ago. Due to the coalescence of the flanks of the volcanoes composing the Island of Hawaii, the older mountain flanks have been overlapped and buried by recent volcanic eruptions;

therefore, the evolution of the broad dome shape of the Island of Hawaii is visible today.

The summit elevation of Mauna Kea Volcano resides at about +13,796 feet Mean

Sea Level (MSL), and the summit elevation of Mauna Loa Volcano resides at about

+13,679 feet MSL. The broad, high elevation region of the Humuula Saddle is located between the summits of the Mauna Kea and Mauna Loa Volcanoes. The elevation of the Humuula Saddle region is on the order of approximately +6,500 feet MSL.

As an illustration of the recent volcanic activity on the Island of Hawaii, over the past 150 years or so, Mauna Loa Volcano has averaged a caldera eruption approximately every few decades. Kilauea Volcano continues an on-going active eruption cycle, which has spanned continuously since about 1983. Therefore, the southern and eastern portions of the Island of Hawaii remain volcanically active whereas toward the north, volcanism appears to be in its waning stages.

A sixth volcano, Loihi, which is presently an active submarine volcano, lies offshore of the southeast coastline of the Island of Hawaii and may emerge some hundreds of thousands of years in the future. Due to the presence of ongoing volcanic activity at Mauna Loa, Kilauea, and Loihi, the Island of Hawaii is located in a zone of active seismic influence. The Island of Hawaii experiences frequent light to moderate earthquakes associated with the movement of underground magma and shifting of the earth’s crust under the weight of the growing island formation. Occasional large

W.O. 4984-30 & 40 GEOLABS, INC. Page 6 earthquakes are usually less frequent based on recorded historic occurrence and may involve geologic fault rupture and lateral offset.

3.2 Local Site Geology

The Saddle Road East Side Alignment between Milepost 11 and Milepost 5.6 is on the broad easterly facing mountain slopes formed by the coalescence of lava flows, which erupted from the Mauna Kea and Mauna Loa Volcanoes. In the vicinity of the proposed Saddle Road East Side Alignment, the older weathered lava flows associated with Mauna Kea Volcano are buried by younger lava flows that were erupted from

Mauna Loa Volcano in historic time and in the late Holocene Epoch. These younger lava flows generally extend from the summit region of Mauna Loa Volcano toward the north and east directions. The northerly flowing lavas banked against the southerly facing flank of Mauna Kea Volcano and were diverted further downslope toward the easterly direction, where some of the historic flows approach the outskirts of Hilo. The exposed lava flows mapped at the ground surface along the project alignment are shown on the Geology Map, Plate 4.

In sporadic locations where the youngest surface lava flows from Mauna Loa

Volcano are thin in coverage, the older slightly more weathered lava rock formations erupted from Mauna Loa may be exposed locally at the ground surface. The existing

Saddle Road alignment between Milepost 11 and Milepost 5.6 generally was constructed following the natural ground surface topography resulting from these recent lava flows, which extend east-northeasterly down slope toward Hilo.

Based on our geological literature review and geotechnical field exploration for this project, the Saddle Road East Side Alignment generally traverses surface basaltic rock lava flows consisting mainly of pahoehoe type lava with some localized a’a type lava with very minimal surface soil exposure between Milepost 11 and Milepost 8. In the

Kaumana area at the far eastern end of the project (from about MP 8 to MP 5.6), the alignment traverses ground that appears to be underlain by thick deposits of volcanic ash materials that are located at the ground surface, and potentially buried in the shallow subsurface beneath some lava rock cover.

W.O. 4984-30 & 40 GEOLABS, INC. Page 7

During bulldozer trail clearing work conducted for our field exploration access, some thin brownish to blackish colored silty organic soils were observed to be exposed at the ground surface. These surface soils were distributed sporadically along the access trails. In addition, some thin silty, sandy, and gravelly near-surface fill soils were encountered along the existing unpaved Saddle Road shoulders. Finally, loose cobbles and boulders typically up to about 2 feet in dimension were produced by near-surface excavation and material spreading activities performed by heavy construction machinery for the purpose of developing the field exploration access trails.

Based on our review of available regional-scale geologic maps, the lava flow(s) comprising the ground surfaces of the existing and proposed Saddle Road East Side

Alignment between Milepost 11 and Milepost 5.6 belong to the Ka’u Volcanic Series

Unit k5, as shown on the Geology Map (Plate 4). The Unit k5 erupted from the summit and northeast rift zone of the Mauna Loa Volcano in 1855. The lava flow is characterized as pahoehoe type lava with some minor a’a type lava inclusions.

Other older basaltic rock ranging in age on the order of about 3,000 to

5,000 years old (mapped as Unit kly) is believed to underlie the recent Unit k5 materials.

Surface exposure of the older lava flows (Unit kly) generally is very limited in occurrence within the proposed road alignment due to the overlap and coverage by the more recent lava flow mapped as Unit k5. It should be noted that most of the proposed Saddle Road

East Side Alignment (and the existing Saddle Road alignment) generally follows the flow path of the younger Unit k5 lava flow(s).

Due to the relatively young geologic age of the historic Unit k5 lava flow, the native vegetation covering the lava flows typically is less dense and of lower maturity with fewer large trees than the other surrounding areas underlain by older lava flows. In general, the proposed road alignment between Milepost 11 and Milepost 8 traverses rocky terrain vegetated with thick fern and brush with scattered trees (effectively obscuring the ground surface). Open ground typically is limited to the existing roadway corridor and adjacent power line access and jeep trails. In addition, the development of surface water drainage features such as eroded gulches and stream gullies is notably subdued along this portion of the alignment and on the broad mountain slopes located

W.O. 4984-30 & 40 GEOLABS, INC. Page 8 further toward the south of the project site. It is believed that the youthful landscape created by the recent surface lava flow events has not had sufficient time to develop erosional surface drainage features on the porous rock surfaces, despite the relatively abundant rainfall that the area receives. The exception being the far eastern end of the proposed road alignment where some developed surface streams intersect the proposed Saddle Road alignment between about Station 1760+00 and approximately

Station 1860+00.

A regional volcanic ash deposit (Pahala Ash, Unit pha) is believed to reside at the surface and in the shallow subsurface within the portion of the project site located between about Station 1742+00 and about Station 1864+00 at the far eastern end of the alignment as shown on the Geology Map, Plate 4. The regional volcanic ash deposit

(mapped as Pahala Ash) is believed to be older than the surrounding surface lava flows located in the vicinity of the project site. It is believed that the Pahala Ash materials were deposited as widespread air-fallout of volcanic ash, which was explosively erupted from regional volcanic vents.

The Pahala Ash materials may be encountered as relatively thick, soft and loose clayey silt and fine sandy soils located at the surface and buried in the subsurface throughout the Island of Hawaii. The term Pahala Ash has been used widely to identify nearly all of the significant volcanic ash deposits located throughout the Island of

Hawaii, regardless of age and the location of the source vent. For example, the

Pahala Ash encountered on the southern flank of Mauna Loa Volcano and those encountered on the flanks of Kilauea Volcano were generated from explosive eruptions at Kilauea Volcano. In contrast, the Pahala Ash encountered in the vicinity of Hilo (and the Saddle Road project site) and along the Hamakua Coast are from explosive late stage eruptions at Mauna Kea Volcano. Therefore, the thickness and age of the Pahala

Ash encountered throughout the Island of Hawaii varies with location and the distance from the vent source(s). Furthermore, more recent lava flow activity from Mauna Loa and Kilauea Volcanoes has partially buried the older ash deposits leaving only isolated pockets of surface exposure of the volcanic ash soils.

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Based on our site reconnaissance and experience with other projects located in the vicinity of the Saddle Road project site, the volcanic ash soils located in the vicinity of the project site are exposed at the ground surface and also may be buried at shallow depths beneath the surface pahoehoe lava flows in the Kaumana area. The thickness of the basalt rock cover overlying the buried volcanic ash materials that have been encountered in the Kaumana area may range from less than about 3 feet to over 15 feet in thickness. It should be noted that the presence of the volcanic ash materials may range from continuous to widely scattered occurrences. In addition, the volcanic ash materials may be encountered at varying depths in the subsurface.

The majority of the near-surface basaltic rock encountered within the project limits is from the eruption of recent pahoehoe lavas from the Mauna Loa Volcano. The age of the main pahoehoe lava flow within the project limits is approximately 150 years

(deposition Year 1855) or less.

A’a lavas typically encompass thick, rubbly, and irregular clinker surfaces consisting of loosely indurated (welded) basalt rock fragments (cobble to small boulder size) and occasional embedded large blocks of dense rock. The thickness of the typical surface clinker layer encountered at the project site is estimated to average on the order of about 5 to 15 feet with some clinker materials extending to depths up to about 20 feet below the existing ground surface.

Below the surface clinker rubble, very dense and often massive basalt rock locally termed as “blue rock” may be encountered. The dense rock contains the solid core of the a’a lava flow, which may range up to several tens of feet in thickness. The a’a lava flows typically advance down slope at a slow pace due to the viscous character of the thickened lavas; therefore, there is typically greater surface topographic relief associated with the deposition of a’a lava flows. The surface relief takes the form of irregular “choppy” terrain encompassed by steep-sided, elevated mounds of “piled” rocks, which may be located adjacent to topographic depressions. The surface of the a’a lava flows generally is very porous due to the rubbly clinker character, which encompasses considerable void space between the “piled” rock fragments.

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In contrast, pahoehoe lava flows typically encompass thinner, less viscous lavas that flow more rapidly as successive layers typically averaging about 3 to 10 feet in thickness, with only limited inter-stratified clinker materials. The pahoehoe lava flows may be thicker where underlying topographic depressions were filled as a result of ponded lava. The pahoehoe lava flows also may be very thin where the lava streamed faster over steeper underlying terrain. Pahoehoe lava flows typically comprise lower relief terrain generally consisting of low height hummocky ground containing frequent open surface cracks and crevices derived from the cooling of the rock layers. The pahoehoe flow surface is generally hard with a limited mantle of clinker materials.

Pahoehoe lavas generally are less porous than the surface clinker of a’a lavas;

however, the multitude of open surface cracks readily permits water percolation into the subsurface.

Pahoehoe lavas typically contain internal flow cavities and/or void spaces derived from the transfer and cooling of molten rock within the flow core. The cavities may occur as localized pockets or as elongated lava tubes that may extend for significant distances (miles) along the lava flow lobe. Lava tubes represent the drained conduit that supplied the advancing flow front with molten rock. Lava tubes on the Island of Hawaii may range in size from several feet to over 40 feet in diameter and may consist of tube alignments that branch, converge, plunge, and breach the ground surface. The supporting roof over the buried tube structure may be as thin as several feet and poses as a potential geotechnical hazard for tube structure collapse and overlying ground settlement.

Based on our field exploration, surface pahoehoe lavas were encountered at the western end of the project site between about existing Milepost 11 and Milepost 8.

Occasionally, some pahoehoe lavas may transition locally to a’a lava as a result of changing flow characteristics that occurred during lava deposition.

3.3 General Site Conditions

As mentioned above, the Saddle Road East Side project site is located on the coalesced easterly facing slopes of the Mauna Kea and Mauna Loa Volcanoes. The new roadway is proposed to extend between about Milepost 11 of the existing Saddle

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Road alignment (several miles westerly from the residential area of Kaumana) and about Milepost 5.6 (near the top of the Puainako Street Extension). The proposed road alignment traverses basaltic rock terrain that slopes and rolls variably down toward the east from the western end of the project site. Ground surface elevations range from about +2,850 feet MSL at the western end of the roadway alignment (Milepost 11) to about +1,340 feet MSL at the eastern end of the alignment near the existing

Milepost 5.6.

The length of the proposed new Saddle Road East Side Alignment between

Milepost 11 and 5.6 is approximately 5.4 miles and generally follows the existing roadway corridor with the exception of some lateral offsets from the existing roadway and realignment (straightening) of some of the existing roadway curves.

The existing Saddle Road within the project limits consists of two-lanes with a paved asphaltic concrete roadway surface. The existing paved roadway surface appears to be in generally fair to good condition. The existing travel lanes are approximately 10 feet wide with additional paved shoulder extending about 3 to 4 feet beyond the white stripe. The unpaved grassed shoulder typically is on the order of about 6 to 8 feet wide on each side of the roadway. The existing roadway contains numerous horizontal and vertical curves that generally follow the natural rolling hill slope topography. Based on our observations, earth cuts and fills located along the existing

Saddle Road alignment are limited and generally are less than approximately 1 to 5 feet in height.

Based on our observations, the surface topographic relief of the native pahoehoe lava flows generally is low with some scattered rock formation irregularities consisting of partially collapsed lava flow channels, lava flow pressure ridges, localized shallow open pits, and open cracks and crevices. Ripping of the near-surface pahoehoe lavas using a

Komatsu D275 bulldozer (work associated with installing access trails for drill rig access) encountered hard to occasionally very hard rock zones producing rock fragments typically on the order of about 1 to 2 feet in dimension with little fines.

Most of the roadside terrain along the existing Saddle Road alignment exists as undeveloped forested rock land. There is an overhead power transmission line

W.O. 4984-30 & 40 GEOLABS, INC. Page 12 alignment with associated utility poles, which approximately parallels the existing

Saddle Road alignment. Multiple roadside vehicle trails exist in the vicinity of the utility easement to provide access to the utility poles from the roadway. The access trails appear to have been rough-graded by a bulldozer (by others).

Based on our site reconnaissance, existing structures such as retaining walls, bridges, and culverts were not observed within the project limits. The earthwork construction performed for this portion of the existing Saddle Road appears to have consisted of very limited cut and fill grading, essentially following the natural land surface contour where possible. Therefore, existing cut slopes and large fill embankments generally were not observed along the existing Saddle Road alignment.

Established stream channel and natural drainage gully features could not be identified on the relatively young, porous basalt rock surfaces that cover the project site.

3.4 Climate

Over the ocean near Hawaii, rainfall averages between 25 and 30 inches a year.

The islands receive as much as 15 times that amount in some places and less than one third of it in others. This phenomenon is caused mainly by orographic or mountain induced rains, which form within the moist trade wind air as it moves from the sea over the high terrain of the islands. Precipitation amounts typically are greatest over the mid-mountain slopes and hill crests and are least in the leeward lowlands. On the higher mountain slopes, the belt of maximum trade wind induced rainfall typically lies between about Elevations +2,000 and +3,000 feet MSL, and precipitation amounts usually decrease rapidly with higher elevations, except during cyclonic storm conditions.

The project site spans between about Elevation +2,850 feet MSL near

Milepost 11 and about Elevation +1,340 feet MSL near Milepost 5.6. Based on a review of the rainfall distribution map presented in the Atlas of Hawaii (Third Edition), the mean annual rainfall in the vicinity of the project site is relatively high to very high and ranges from about 160 to over 240 inches of rainfall per year, depending on the elevation of the east facing mountain slopes. The relatively high annual rainfall is the result of the project site location with respect to a belt of maximum orographic precipitation just west of Hilo.

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Lower precipitation often is experienced during the summer months of June and

July. Regionally, the typical rainfall distribution increases most dramatically over relatively short distances below about Elevation +5,500 feet MSL as lower elevation areas further toward the east are approached from the west.

Based on a review of Koppen climate information pertaining to the project site and vicinity, the project site spans a climatic transition zone between a coastal Humid-

Tropical (Af) Climate and an inland upslope Temperate Climate (Cfb). Based on the available maps, the climate transition zone appears to be near the +3,000 to

+4,000-foot MSL Elevation zone along the existing Saddle Road. The Af climate regime may be characterized as tropical, continuously wet and encompasses the coastline and lower mountain slopes westerly of Hilo, including the majority of the project site. The Cfb climate regime may be characterized as continuously wet, warm, and temperate and extends further upslope toward the Humuula Saddle area between the peaks of the

Mauna Kea and Mauna Loa Volcanoes.

Based on our observations, typical rainfall generally was observed to be light to moderate in intensity consisting of fog drip and misty rainfall at elevations greater than about +3,000 feet MSL. Below approximately +3,000 feet MSL, rainfall is typically of greater intensity with frequent moderate to heavy precipitation. Due to the close proximity of the volcano summits and upland slopes, afternoon heating of the landmass may produce cumulus cloud buildups, which result in locally heavier downpours that generally terminate in the cooler early evening hours. At elevations greater than about

+5,000 feet MSL, evaporation of moisture was observed to be appreciably greater.

The average daytime air temperatures (in degrees Fahrenheit) range between the 70s and 80s at the project site with abrupt temperature changes occurring with the formation of afternoon clouds and rain showers. Night-time temperatures average in the

60s to 70s. It should be noted that low cloud and fog formation is a common occurrence especially between about Elevations +3,000 and +6,000 feet MSL.

3.5 Geologic Materials

The geologic materials encountered at the ground surface along the proposed roadway alignment consist of basaltic lava rock identified as Geologic Material Type

W.O. 4984-30 & 40 GEOLABS, INC. Page 14

Nos. 1 through 3 and volcanic ash soil identified as Geologic Material Type No. 4. The basaltic rock formations encountered by our field exploration consists of two general types of lava flows identified as pahoehoe (Geologic Material Type No. 1) and a’a

(Geologic Material Type No. 2) lavas. Geologic Material Type No. 3 consists of fill materials (including rocks, cobbles, and boulders with some sand and gravel) that generally are encountered within the existing roadway prism along the existing Saddle

Road alignment. Geologic Material Type No. 4 consists of pyroclastic ash deposit of clayey silts with fine sands. The generalized types of geologic materials encountered at the ground surface along the proposed roadway alignment are summarized as follows.

GEOLOGIC

MATERIAL

GENERAL

DESCRIPTION

Type No. 1 Basalt Rock Lava Flow, Limited Surface Clinker with Thinner Layered Vesicular Lava Flows, Medium Hard to Hard Rock (Pahoehoe Basalt Rock)

Type No. 2

Basalt Rock Lava Flow, Thicker Rubbly Clinker Surface with Interior Core of Dense Vugular Basalt Rock, Loose to Very Hard Rock (A’a Basalt Rock)

Type No. 3 Fill Materials, including Rocks, Cobbles and Boulders with some Sand and Gravel, Medium Dense to Dense (Recent Fill)

Type No. 4 Pyroclastic Deposit, Clayey Silt with Fine Sand, Very Soft to Medium Stiff in Consistency (Volcanic Ash)

Based on our review of available geologic map information in conjunction with our field exploration, we believe the project site is underlain primarily by Geologic

Material Type No. 1 (Pahoehoe Basalt Rock) with localized spots of Geologic Material

Type Nos. 2 and 4 (A’a Basalt Rock and Recent Fill for the portion of alignment extending from Sta. 1545+00 to Sta. 1742+00. The basaltic rock formations (Geologic

Material Type Nos. 1 and 2) encountered at the ground surface of the project site belongs to the Ka`u Volcanic Series, which erupted from Mauna Loa Volcano within the past 150 years. The fill materials representing Geologic Material Type No. 3 typically is associated with the construction of the existing Saddle Road alignment. The proposed

W.O. 4984-30 & 40 GEOLABS, INC. Page 15 new road alignment frequently traverses or crosses the graded old roadway corridor where the recent fills may be encountered. Based on our field reconnaissance and test boring exploration, pahoehoe lavas (Geologic Material Type No. 1) were encountered most commonly along this portion of the alignment at the project site. Based on our reconnaissance, a’a lavas (Geologic Material Type No. 2) are anticipated to cover a small portion of the natural rock surfaces along this portion of the proposed road alignment. Areas of fill materials are assumed to exist within the existing roadway prism.

The location of the recent fills cannot be accurately identified by field reconnaissance due to the existing pavement cover, limited surface exposure, and lack of as-built grading plans.

The far eastern portion of the alignment between about Sta. 1742+00 and about

Station 1864+00 generally is underlain by Geologic Material Type No. 4, which consists of some older volcanic ash materials (Pahala Ash) erupted from the Mauna Kea

Volcano more than about 5,000 years ago. The clayey silt ash soils were exposed at the ground surface and may be buried in the shallow subsurface at the eastern end of the project site. The following are brief descriptions of the Geologic Material Type Nos. 1 through 4.

3.5.1 Geologic Material Type No. 1

The Pahoehoe Basalt Rock (Geologic Material Type No. 1) typically consists of more fluid lava that flowed more rapidly, as successive flow layers averaging about 3 to 10 feet in thickness, with only limited inter-stratified clinker seams. The lava flows may be thicker where underlying depressions were filled as a result of ponded lava or very thin where the lava streams flowed readily down steeper underlying terrain. Pahoehoe lava flows typically comprise flatter terrain containing lower topographic relief. Pahoehoe lava typically forms hummocky ground surfaces with frequent ground pits and surface cracks and crevices derived from the deposition and cooling of the molten rock layers. The pahoehoe flow surface generally is hard with a limited mantle of clinker material. Pahoehoe lava flows generally are less porous than the surface clinker comprising a’a lavas; however, the multitude of open surface cracks readily permits water percolation into the subsurface.

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Pahoehoe lavas typically contain internal flow cavities and/or void spaces derived from the transfer and cooling of molten rock within the flow core. The cavities may occur as localized pockets or as elongated lava tubes that may extend for significant distances (miles) along the lava flow lobe. Lava tubes represent the drained conduit that supplied the advancing flow front with molten rock. Lava tubes may range in size from several feet to over 40 feet in diameter and may consist of tube alignments that branch, converge, plunge, and breach the ground surface. The supporting roof over the buried tube structure may be as thin as several feet and poses as a potential geotechnical hazard for tube collapse and overlying ground settlement.

3.5.2 Geologic Material Type No. 2

The A’a Basalt Rock (Geologic Material Type No. 2) typically consists of thick, rubbly, and irregular clinker surfaces consisting of loosely indurated (welded) basalt rock fragments (cobble to small boulder size) with layer thickness generally on the order of about 5 to 20 feet. Below the clinker rubble surface, very dense and often massive basalt rock locally termed as “blue rock” may be encountered. The dense rock contains the core of the a’a lava flow, which may range to several tens of feet in thickness. The flows advanced down slope at a slower pace due to the thickened viscous character of the lava; therefore, there typically is greater surface topographic relief associated with the deposition of a’a lava flows. The surface relief takes the form of rolling terrain encompassed by steep-sided, elevated mounds of “piled” rocks located adjacent to topographic depressions. The surface of the a’a lava flows generally is very porous due to the rubbly clinker character, which encompasses considerable void space between the “piled” rock fragments.

3.5.3 Geologic Material Type No. 3

The Recent Fills (Geologic Material Type No. 3) typically consist of various basaltic rock cobbles and boulders with some sands and gravel placed as fills for the construction of the existing Saddle Road. Because the existing Saddle Road appears to have followed the pre-existing grades with few earth cuts, most of the existing fills appear to be on the order of about 1 to 5 feet in thickness.

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3.5.4 Geologic Material Type No. 4

The Volcanic Ash (Geologic Material Type No. 4) typically consists of a soft to medium stiff reddish brown clayey silt with fine sand, which may be encountered at the ground surface and buried at shallow depths beneath the surface pahoehoe lava flows in the Kaumana area at the eastern end of the project site.

The thickness of the basalt rock cover overlying the buried volcanic ash materials that have been encountered in the Kaumana area may range from less than about 3 feet to over 15 feet in thickness. It should be noted that the presence of the volcanic ash materials may range from continuous to widely scattered occurrences. In addition, the volcanic ash materials may be encountered sporadically at varying depths in the subsurface.

3.6 Existing Site Conditions

The following discussion provides a general description of the existing surface conditions that were observed during our site reconnaissance and field exploration activities conducted at the project site. The discussion includes a description of the geologic materials encountered and some other features and site conditions that may be pertinent to the site characterization and design of the proposed project.

3.6.1 Station 1545+00 to Station 1696+00

The proposed alignment traverses mainly moderate relief rock surface topography associated with a’a basalt rock deposition. The terrain generally is gently to moderately inclined down toward the easterly direction. The proposed alignment follows and/or parallels the existing roadway alignment with some minor lateral shifts away from the existing road. The ground surfaces within this section of the proposed road alignment primarily are underlain by pahoehoe basalt rock (Geologic Material Type No. 1).

The proposed baseline cuts ranging from about 2 to 6 feet are typical. Some proposed deeper baseline fills ranging up to about 12 to 16 feet are planned as higher relief surface rock formations are traversed locally by the roadway. An existing overhead power line and utility pole alignment with associated access trails is on the north side of the proposed new roadway corridor.

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3.6.2 Station 1696+00 to Station 1721+00

Geological reconnaissance and test boring data indicate that this area is underlain by vesicular basaltic ‘pahoehoe’ lava flows of at least 21 to 38 feet in thickness. The rocks in this formation are hard, unweathered, and moderately to closely fractured. When molten, this fluid lava flowed like a river and the resulting rock surface has a ropy, smooth and undulating character. Prone to the creation of lava tubes, the pahoehoe in this area has many cracks and holes The land surface dips gently down toward Hilo with an average gradient ranging from

33H:1V to 17H:1V. Planned fills up to 8 feet and cuts up to 23 feet in this area will consist of largely this material. Moderately dense vegetation of ferns, ohia trees and mosses provide a thin veneer of organic silt over the basalt in the low points of the undulations generally less than 3 inches thick.

3.6.3 Station 1721+00 to Station 1742+00

Surface mapping shows that this section also is dominated by pahoehoe basalt geomorphology. Test borings reveal that the surface flows are 20.5 to 26 feet thick overlying medium dense to dense A’a clinker of approximately 1 to 8 feet thick, which then grades to very hard A’a basalt below. Gradients in this area are similar to the previous section with one relatively steeper area between

Station 1727+50 to Station 1730+00 where the ground surface elevations drop sharper at approximately 5H:1V. Planned fills up to 14 feet and cuts up to 24 feet likely will involve rippable pahoehoe materials but may encounter some clinker near the bottom of the deepest cuts. Vegetation in this area is similar to the previous one with the addition of numerous guava and some bamboo trees.

3.6.4 Station 1742+00 to Station 1766+50

Pahoehoe outcrops pinch out from the surface throughout this section. Surface mapping and hand probe data indicate that this area is blanketed by a soft to medium stiff volcanic ash and/or alluvial soil layer of about 2 to 3.5 feet thick overlying weathered clinker with occasional fingers of thin pahoehoe basalt near the surface. Test borings in these areas indicate that the clinkery silty gravel and cobble deposits extend at least 6 to 23 feet below the existing ground surface.

Boring No. 233 encountered very hard A’a basalt at a depth between about 6 and

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13 feet overlying a 10-foot thick soft volcanic ash bed to a depth of about 23 feet overlying pahoehoe basalt. The land slopes gradually down to the east throughout this section with average gradient ranging from approximately 20H:1V to 13H:1V. The cuts up to 9 feet deep likely will encounter predominantly clinkery gravel and cobbles with significant silt and sand. A small intermittent stream channel transects the proposed roadway near Station 1765+00. The area is moderately to heavily vegetated within this section with foliage ranging from tall grasses to medium large trees and occasional large albesio trees.

3.6.5 Station 1766+50 to Station 1771+50

Surface mapping and hand probe data indicate that this section is characterized by a thin (less than 2.5 feet) soil layer over pahoehoe basalt. Boring No. 235 suggests that this pahoehoe layer is also thin (about 2.5 feet thick) and is underlain by a 7.5-foot thick layer of soft volcanic ash to a depth of about 12 feet overlying pahoehoe basalt to a depth of a least 21.5 feet below the existing ground surface. An intermittent stream channel exposes the upper layer of pahoehoe basalt between Station 1767+20 and Station 1769+50. Ground surface elevations dip gently across this sector toward the east at an average gradient of approximately 14H:1V. Thick tropical forest ends near Sta. 1766+00 and gives way to open field grasslands with small trees.

3.6.6 Station 1771+50 to Station 1776+50

Reconnaissance, hand probing and test borings indicate that this expanse is blanketed by a thick soft to medium stiff volcanic ash layer about 11 to 12 feet thick overlying pahoehoe basalt to at least 18.5 feet below the existing ground surface. The pahoehoe basalt is exposed in a depression at approximate

Station 1774+25 and in the intermittent stream channel at Station 1776+50. The land slopes very gradually down to the east at a gradient of roughly 38H:1V.

Planned fills in this area of up to 14 feet will begin in the ash material and significant settlement is anticipated and should be accounted for. The vegetation in this area consists of tall grasses and is believed to be a section of the former golf course that occupied this area.

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3.6.7 Station 1776+50 to Station 1793+20

Geological reconnaissance and Boring Nos. 237 and 238 indicate that this section of the alignment is characterized by pahoehoe basalt. Thin organic soils that overlie this formation are generally less than 6 inches thick. The rock is exposed at the surface and extends to depths of at least 21.5 feet below that ground surface. The ground surface undulates throughout this expanse, but it generally slopes down to the east at an average gradient of 14H:1V with locally steeper gradients of 5H:1V. Proposed fills up to 20 feet and cuts up to14 feet likely will encounter hard pahoehoe material. Aside from where this section of the alignment crosses Pulima Road, this area is heavily forested.

3.6.8 Station 1793+20 to Station 1850+50

This long expanse is dominated by soft to medium stiff volcanic ash deposits.

Boring No. 239, drilled in the channel of a broad river valley encountered only

2 feet of volcanic ash over pahoehoe basalt while Boring Nos. 240 through 247 encountered approximately 7 to 14 feet of soft volcanic ash over pahoehoe basalt, which extended to the maximum extent of the depths drilled. Elevation gradients vary throughout this region ranging from nearly flat from

Station 1796+00 to Station 1799+50 to approximately 11H:1V down toward Hilo from Station 1802+00 to Station 1807+00. The remaining sections feature gentle average gradients ranging from 12H:1V to 15H:1V with occasional steeper sections near the stream valleys in the area.

Stream channels were encountered at Station 1794+50, Station 1804+50, Station 1808+50, Station 1822+00, Station 1841+50, Station 1847+00 and

Station 1850+00. Limited cuts up to about 12 feet deep are planned in this area while extensive fills up to 32 feet are proposed over the native volcanic ash soils.

Heavily forested from Station 1793+20 to Station 1796+00, the landscape opens up to a wide grassy field down to Station 1804+00 where the alignment crosses another stream valley. Heavy forest vegetation characterizes the alignment down to Station 1808+50 where grassy fields and ferns dominate the foliage. Ferns, grasses, and a line of fir trees run down toward Country Club Drive at

Station 1819+00. Grassy pasture lands dominate the scenery down to

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Station 1835+50. Heavy forest…