B08_Attach_7_Title_II_100__Final_Consultation_Letter_0004.pdf

July 1, 2021

MFA Project No. 21629-011

Warren W.K. Lau

MASON

119 Merchant Street, Suite 501 Honolulu, Hawaii 96813 wl@masonarch.com

Subject: Geotechnical Consultation Letter Construct New Fuel Storage and Dispensing System – PMIS #248432 Kalaupapa National Historic Park

Moloka’i, Hawai’i

Masa Fujioka & Associates (MFA) is pleased to submit this consultation letter for the subject project.

MFA was consulted to assess existing site conditions in order to verify engineering design assumptions for the subject project. We understand that a fueling facility is planned and is in late stages of the design process. We also understand that no previous geotechnical investigation was performed and that no previous geotechnical engineering, or soils report was submitted. This letter details the scope of work performed and presents our findings and recommendations.

1.0 DATA REVIEW

We reviewed published geological and soils data, as well as the 100-percent final submittal drawings.

The subject project is situated within Kalaupapa National Historic Park, in Kalawao County, on the island of Moloka’i.

The subject project area is mapped to be underlain by pleistocene basalt belonging to the Kalaupapa Volcanics series, and soils within the project boundary are mapped as Haleiwa very stony silty clay loam.

Basalt belonging to the Kalaupapa Volcanics series consists of rock formed from pāhoehoe lava flows that built the Kalaupapa Peninsula during the middle to late Plesitocene, estimated at 0.57 to 0.34 million years ago (Ma).

Haleiwa very stony silty clay loams are generally present on the islands of O’ahu and Moloka’i. Soils of this type are considered to have medium permeability; runoff is considered slow to medium, with moderate erosion hazard. It is present at elevations ranging from sea level to 250 feet. These soils developed in alluvium derived from basic igneous rock.

Geotechnical Consultation Letter

2.0 GEOTECHNICAL INVESTIGATION AND LABORATORY TESTING

2.1 SITE RECONNAISSANCE AND TEST PIT EXCAVATIONS

On June 10, 2021, a geotechnical field investigation was conducted by the National Park Service (NPS) and MFA. An NPS equipment operator performed excavation of two (2) test pits under the direction and observation of an MFA Project Engineer.

The test pits were excavated using a backhoe excavator, operated by NPS and measured approximately five feet by ten feet in lateral dimensions. The existing ground surface consisted of grass and other vegetation several inches tall. Bulk soil samples were recovered and brought to MFA’s soils laboratory for visual classification and testing.

The backhoe experienced mechanical problems and field work was halted midway through the day.

As a result, only two (2) of the four (4) anticipated test pit excavations were completed. Two (2) bulk soil samples were collected for laboratory analysis from each of the completed test pits. Following the collection of the samples, both excavations were backfilled.

We observed and noted the following during our geotechnical field investigation:

- According to NPS staff, the subject project area had no known history of grading or previous construction. The site may have been utilized for cattle grazing.

- A single 2-inch diameter pipe was encountered in test pit TP-1, trending east-west across the excavation, at a shallow depth. The pipe did not appear to be in service.

- No topographic survey was performed as part of our field visit.

2.2 LABORATORY ANALYSIS

The bulk soil samples were taken at depths of one-foot below the ground surface (bgs), and five-feet bgs. Laboratory testing of the samples consisted of identification tests (Gradation and/or Atterberg Limits) and were conducted in MFA’s soils laboratory, which is accredited by AASHTO and validated by the US Army Corps of Engineers.

The bulk soils taken at 1-foot bgs in both test pits classified as sandy silt (ML), with Atterberg limits tests yielding liquid limit and plasticity indices of 47 / 18% respectively, in test pit TP-1, and 39 / 9% respectively, in test pit TP-2. Soils taken at 5-feet bgs classified as silty gravel with sand (GM), with liquid limits and plasticity indices of 60 / 20% respectively, in test pit TP-1, and 46 / 18% respectively, in test pit TP-2.

2.3 FINDINGS

The excavation of test pit TP-1 encountered brown sandy silt interbedded with highly weathered basaltic stones and cobbles to approximately 3-feet bgs. From 3-feet bgs, the soils graded to reddish-brown silty gravel, with sand with basaltic stones and cobbles. A layer of moderately weathered, lightly fractured basaltic rock, less than 6-inches thick, was encountered at an approximate depth of 4-feet bgs. The excavator experienced refusal upon encountering a layer of lightly weathered blue-grey basaltic rock at 5-feet bgs, at which depth the excavation was terminated.

Excavation in test pit TP-2 encountered similar subsurface soil conditions as test pit TP-1, and the excavation was terminated at a depth of approximately 5-feet bgs.

Groundwater was not encountered in either of the test pit excavations.

3.0 RECOMMENDATIONS

3.1 FOUNDATIONS AND STRUCTURES

Gradation and Atterberg limits tests were performed on soils collected from the project area and were classified as sandy silt (ML) and silty gravel with sand (GM). Note that basaltic cobbles and boulders were encountered from the existing ground surface to the bottom of the excavations.

We understand that the proposed structures are to be founded on spread footings located at depths of approximately 3-feet bgs. Based on the above, we recommend designing foundations for structures with the following parameters:

Soil vertical bearing capacity: 2,000 PSF Soil lateral bearing capacity: 150 PSF per foot below grade Friction Coefficient: 0.25

We recommend checking for the presence of subsurface voids within the footprint of the proposed structures due to the potential for voids within basaltic rock. Checking for and remediation of voids is normally performed by proof rolling with a heavy vibratory compactor, under the observation of a Geotechnical Engineer. We understand that use of a heavy vibratory compactor at the site may not be practical. As an alternative, over-excavation of the subgrade to at least 2-feet below the bottom of the structure, and a lateral distance of 2-feet beyond the structure, followed by replacement with compacted structural fill, can be performed. We understand that due to site limitations, over-excavation of 2-feet vertically and laterally may also not be practical. In lieu of proof rolling and over-excavation, we recommend jackhammer probing to a minimum depth of 5-feet below the excavation floor be performed at 5-foot x 5-foot intervals within the planned excavation. Any voids encountered during probing activities should be filled with a neat cement grout having a minimum 28-day cured compressive strength of 3000 psi.

3.2 PAVEMENTS

We understand that per the design drawings, areas with vehicular traffic are to be supported with compacted aggregate, with the option for rigid concrete pavement. If rigid pavements are intended for the project, we recommend further laboratory analysis of on-site soils to provide pavement structure recommendations.

4.0 EARTHWORK

Based on the soil conditions encountered during MFA’s geotechnical investigation, near surface soil encountered during construction will likely consist of sandy silts interbedded with basaltic cobbles and boulders. Groundwater was not encountered and is not anticipated to be of concern for near surface earthwork activities.

4.1 SITE PREPARATION

The ground surface where construction is proposed should be cleared, stripped, and grubbed to a depth sufficient to remove all vegetation, roots, and other debris.

Subgrade preparation underlying structures, pavements, and sidewalks should consist of the following, for areas where the subgrade consists of sandy silts:

Subgrade soils should be reviewed by the Geotechnical Engineer by direct observation and by compaction, or proof rolling with a heavy vibratory compactor, to check for any near-surface cavities or voids. We understand that due to site limitations, proof rolling may not be feasible; probe and grout may be conducted as an alternative.

Any overly soft or weak areas indicated by the geotechnical field investigation, compaction, or proof rolling, should be excavated and replaced with compacted, clean structural fill, to the satisfaction of the Geotechnical Engineer.

4.2 FILL MATERIALS, PLACEMENT, AND COMPACTION

We anticipate that on-site excavated basaltic materials may be stockpiled for subsequent re-use in structural fills at the site. Oversized particles shall be screened or crushed and graded with heavy equipment. Large boulders may be used at other areas of the site, upon approval of others.

Note that the soil characteristics may be variable and should be further reviewed, and possibly inspected and tested by the Geotechnical Engineer, prior to reuse on-site. General requirements for structural fill and granular structural fill follow:

4.2.1 Structural Fill

Structural fill should consist of on-site or imported materials classified by ASTM D2487 as GW, GP, GM, GP-GM, GW-GM, SW, SP, SW-SM, or SP-SM that are free of organic matter, debris, and particles larger than three inches in maximum dimension, with a maximum CBR expansion of 1%.

Structural fill materials used in areas beneath building slabs should have a minimum CBR value of 30%, and fill materials used in pavement subgrade areas should have a minimum CBR value of 10% when tested in accordance with ASTM D1883.

On-site materials may include rock fragments, cobbles, and boulders that should be screened, or crushed and graded to produce materials conforming to the ASTM-D2487 classifications listed above.

4.2.2 General Fill

General fill may be placed in non-structural areas. Materials used for general fill should consist of imported materials classified by ASTM D2487 as GW, GP, GM, GP-GM, GW-GM, GC, GP-GC, GM-GC, SW, SP, SM, SC, SW-SC, SW-SC, SP-SM, SP-SC that are free of organic matter, debris, and particles larger than three inches in their maximum dimension.

4.3 FILL PLACEMENT AND COMPACTION

All structural fill materials under building slabs or pavements should be moisture conditioned to within 3% of optimum moisture and compacted to a minimum 95% of maximum density (ASTM D1557).

Satisfactory structural and general fill materials should be placed in 8-inch maximum, loose lifts and compacted utilizing compaction equipment. The loose lift thickness should be reduced to 6-inches when placed and compacted in confined areas, such as beneath or adjacent to footings, or in utility trenches. Where power driven, hand-tampers (i.e. “jumping jacks”) are used, the maximum loose lift thickness should also be reduced to 6-inches. In areas where footings are formed, the remaining annulus between the footing edge and the excavation face should be wide enough to allow hand-held equipment to compact the backfill material.

On-site soils and general fill materials placed in general, non-structural areas, should be within 3% of the optimum moisture content and compacted to 90% of the maximum dry density for granular soils and 85% for cohesive soils as determined by ASTM D1557.

If the fill materials become overly wet during placement and compaction due to rainfall during placement, or start to “pump” as a result of over compaction, the fill lift should be scarified and allowed to dry sufficiently to enable compaction, or removed and replaced with drier fill material.

5.0 GEOTECHNICAL MONITORING DURING CONSTRUCTION

We recommend that a Geotechnical Engineer be retained to provide geotechnical services during construction, including monitoring of excavations, subgrade preparation, and earthwork activities including observing proofrolling, laboratory testing of on-site or imported soils, and in-situ compaction testing.

6.0 LIMITATIONS

The geotechnical recommendations presented in this consultation letter are based on the following assumptions:

1. The scope of the construction project, as described, does not change appreciably.

2. Significant variations in soil and rock properties from those encountered during our investigation do not occur.

3. A Geotechnical Engineer will be retained to observe actual field conditions encountered during construction to check the applicability of the recommendations presented in this consultation letter, and to recommend appropriate changes in design or construction procedures, if differing conditions occur.

This letter was prepared for the use of MASON in accordance with generally accepted geotechnical engineering principles and practices and may not be suitable for the use of other parties.

Our services were provided consistent with normal standard of practice. No other representation is intended or implied.

Figure 2, Laboratory Tests

ML Brown sandy silt interbedded with highly weathered basaltic cobbles and boulders

GM Grades to red/brown silty gravel w/ sand interbedded with highly weathered basaltic cobbles and bouldersRX Grey/blue igeneous basaltic rock, lightly weathered, lightly fractured Excavation terminated upon excavator refusal at

5' bgs

Gradation Note: Pocket penetrometer (PP) readings taken in soft materials

PP: >4.5 TSF

PP: 3.5 TSF

G W

T n ot e nc ou nt er ed

National Park Service (NPS) Kalaupapa Fueling Station

629-011

Molokai'i Island, HI

Logged By: EN Checked By: RTI

Grass

MASON

Test Pit: TP-1

Driller: National Park Service

Drill Method: Backhoe excavator, test pit

Sample Method: Bulk

Borehole Diameter: 5' x 10'

Date/Time Begin : 06/10/21 @ 09:43

Figure: 1.1

Date/Time Finish : 06/10/21 @ 11:50

Location: N 21°11'23.84" W 156°58'45.15"

Bulk Sample: 1' bgs and 5' bgs

S a m p le

B lo w s p e r F o o t

In c h e s D ri v e n

R e c o v e ry

D e p th

F

t) Material Description Tests Performed

MFA Job #:

U S

C S

S o il

Surface Conditions:

R e c o v e re d

S a m p le M e th o d

C la s s if ic a ti o n

R

Q D

Client:

ML Brown sandy silt interbedded with highly weathered basaltic cobbles and boulders

GM Grades to red/brown silty gravel w/ sand interbedded with highly weathered basaltic cobbles and bouldersRX Grey/blue igeneous basaltic rock, lightly weathered, lightly fractured Excavation terminated upon excavator refusal at

5' bgs

Gradation Note: Pocket penetrometer (PP) readings taken in soft materials

PP: 3,25 TSF

PP: >4.5 TSF

PP: 2.0 TSF

G W

T n ot e nc ou nt er ed

National Park Service (NPS) Kalaupapa Fueling Station

629-011

Molokai'i Island, HI

Logged By: EN Checked By: RTI

Grass

MASON

Test Pit: TP-2

Driller: National Park Service

Drill Method: Backhoe excavator, test pit

Sample Method: Bulk

Borehole Diameter: 5' x 10'

Date/Time Begin : 06/10/21 @ 12:00

Figure: 1.2

Date/Time Finish : 06/10/21 @ 12:38

Location: N 21°11'23.86" W 156°58'44.38"

Bulk Sample: 1' bgs and 5' bgs

S a m p le

B lo w s p e r F o o t

In c h e s D ri v e n

R e c o v e ry

D e p th

F

t) Material Description Tests Performed

MFA Job #:

U S

C S

S o il

Surface Conditions:

R e c o v e re d

S a m p le M e th o d

C la s s if ic a ti o n

R

Q D

Client:

Project: Kalaupapa National Historical Park Date Received: 6/11/2021 ASTM: D6913/D1140 Figure: 2.1 MFA Job No.: 629-011 Test Start Date: 6/14/2021 Wash: Method A Sample: TP-1

Client: Mason Architects Inc. Test End Date: 6/25/2021 Soil Class: ML Depth: 1'

Location: Kalaupapa, Molokai Date Reported: 7/1/2021 USCS: Sandy silt

Grain Size Analysis

0.0010.010.1110100

Pe rc en t

Pa ss in g b y W e ig h t

Grain Size in Millimeters

G ra ve l Sa nd

Sa nd

Fi ne

Project: Kalaupapa National Historical Park Date Received: 6/11/2021 ASTM: D6913/D1140 Figure: 2.2 MFA Job No.: 629-011 Test Start Date: 6/14/2021 Wash: Method A Sample: TP-1

Client: Mason Architects Inc. Test End Date: 6/25/2021 Soil Class: GM Depth: 5'

Location: Kalaupapa, Molokai Date Reported: 7/1/2021 USCS: Silty gravel w/ sand

Grain Size Analysis

0.0010.010.1110100

Pe rc en t

Pa ss in g b y W e ig h t

Grain Size in Millimeters

G ra ve l Sa nd

Sa nd

Project: Kalaupapa National Historical Park Date Received: 6/11/2021 ASTM: D6913/D1140 Figure: 2.3 MFA Job No.: 629-011 Test Start Date: 6/14/2021 Wash: Method A Sample: TP-2

Client: Mason Architects Inc. Test End Date: 6/25/2021 Soil Class: ML Depth: 1'

Location: Kalaupapa, Molokai Date Reported: 7/1/2021 USCS: Sandy silt

Grain Size Analysis

0.0010.010.1110100

Pe rc en t

Pa ss in g b y W e ig h t

Grain Size in Millimeters

G ra ve l Sa nd

Sa nd

Project: Kalaupapa National Historical Park Date Received: 6/11/2021 ASTM: D6913/D1140 Figure: 2.4 MFA Job No.: 629-011 Test Start Date: 6/14/2021 Wash: Method A Sample: TP-2

Client: Mason Architects Inc. Test End Date: 6/25/2021 Soil Class: GM Depth: 5'

Location: Kalaupapa, Molokai Date Reported: 7/1/2021 USCS: Silty gravel w/ sand

Grain Size Analysis

0.0010.010.1110100

Pe rc en t

Pa ss in g b y W e ig h t

Grain Size in Millimeters

G ra ve l Sa nd

Sa nd

PROJECT: Kalaupapa National Historical ParkFigure: 2.5 JOB NO: 629-011 Air Dried: Before SAMPLE NO: TP-1 Preparation: Dry LOCATION: Kalaupapa, Molokai Date Received: 6/11/2021 DEPTH: 1' Test Start Date: 6/14/2021 DESCRIPTION OF SOIL: ML Test End Date: 6/25/2021 CLIENT: Mason Architects Inc. Date Reported: 7/1/2021

SAMPLE OR TRIAL NO. 1 2

MOISTURE TIN NO. N/A N/A

WT WET SOIL +TARE (g) 22.50 22.21 WT. DRY SOIL + TARE (g) 21.00 20.74

WT. MOISTURE TIN 15.85 15.58

WT. WATER (g) 1.5 1.47 WT. DRY SOIL (g) 5.15 5.16

MOISTURE CONTENT (%) 29.13 28.49

Plastic Limit = 29 %

SAMPLE OR TRIAL NO. 1 2 3

MOISTURE TIN NO. N/A N/A N/A

WT WET SOIL +TARE (g) 10.48 10.25 10.31 WT. DRY SOIL + TARE (g) 7.69 7.50 7.51 Wt. Tare (g) 1.78 1.76 1.77 wT. WATER (g) 2.79 2.75 2.80 WT. DRY SOIL (g) 5.91 5.74 5.74

MOISTURE CONTENT (%) 47.21 47.91 48.78

No. of Blows 25 21 18

35-25 30-20 25-15

Liquid Limit = 47 % at N = 25 blows Plasticity Index = 18 %

ATTERBERG LIMITS

PLASTIC LIMIT DETERMINATION

LIQUID LIMIT

Masa Fujioka & Associates

47 48 49

PROJECT: Kalaupapa National Historical ParkFigure: 2.6

SAMPLE NO: TP-1 Preparation: Dry LOCATION: Kalaupapa, Molokai Date Received: 6/11/2021 DEPTH: 5' Test Start Date: 6/14/2021 DESCRIPTION OF SOIL: MH Test End Date: 6/25/2021 CLIENT: Mason Architects Inc. Date Reported: 7/1/2021

SAMPLE OR TRIAL NO. 1 2

MOISTURE TIN NO. N/A N/A

WT WET SOIL +TARE (g) 22.22 22.09 WT. DRY SOIL + TARE (g) 20.28 20.24

WT. MOISTURE TIN 15.46 15.63

WT. WATER (g) 1.94 1.85 WT. DRY SOIL (g) 4.82 4.61

MOISTURE CONTENT (%) 40.25 40.13

Plastic Limit = 40 %

SAMPLE OR TRIAL NO. 1 2 3

MOISTURE TIN NO. N/A N/A N/A

WT WET SOIL +TARE (g) 9.99 9.48 9.71 WT. DRY SOIL + TARE (g) 6.93 6.60 6.69 Wt. Tare (g) 1.76 1.79 1.77 wT. WATER (g) 3.06 2.88 3.02 WT. DRY SOIL (g) 5.17 4.81 4.92

MOISTURE CONTENT (%) 59.19 59.88 61.38

No. of Blows 29 23 16

35-25 30-20 25-15

Liquid Limit = 60 % at N = 25 blows Plasticity Index = 20 %

ATTERBERG LIMITS

PLASTIC LIMIT DETERMINATION

LIQUID LIMIT

Masa Fujioka & Associates

59 60 61 62

PROJECT: Kalaupapa National Historical ParkFigure: 2.7

SAMPLE NO: TP-2 Preparation: Dry LOCATION: Kalaupapa, Molokai Date Received: 6/11/2021 DEPTH: 1' Test Start Date: 6/14/2021 DESCRIPTION OF SOIL: ML Test End Date: 6/25/2021 CLIENT: Mason Architects Inc. Date Reported: 7/1/2021

SAMPLE OR TRIAL NO. 1 2

MOISTURE TIN NO. N/A N/A

WT WET SOIL +TARE (g) 22.72 22.54 WT. DRY SOIL + TARE (g) 21.15 20.90

WT. MOISTURE TIN 15.81 15.43

WT. WATER (g) 1.57 1.64 WT. DRY SOIL (g) 5.34 5.47

MOISTURE CONTENT (%) 29.40 29.98

Plastic Limit = 30 %

SAMPLE OR TRIAL NO. 1 2 3

MOISTURE TIN NO. N/A N/A N/A

WT WET SOIL +TARE (g) 12.41 11.40 10.93 WT. DRY SOIL + TARE (g) 9.47 8.69 8.32 Wt. Tare (g) 1.77 1.76 1.79 wT. WATER (g) 2.94 2.71 2.61 WT. DRY SOIL (g) 7.70 6.93 6.53

MOISTURE CONTENT (%) 38.18 39.11 39.97

No. of Blows 35 24 19

35-25 30-20 25-15

Liquid Limit = 39 % at N = 25 blows Plasticity Index = 9 %

ATTERBERG LIMITS

PLASTIC LIMIT DETERMINATION

LIQUID LIMIT

Masa Fujioka & Associates

38 39 40 41

PROJECT: Kalaupapa National Historical ParkFigure: 2.8

SAMPLE NO: TP-2 Preparation: Dry LOCATION: Kalaupapa, Molokai Date Received: 6/11/2021 DEPTH: 5' Test Start Date: 6/14/2021 DESCRIPTION OF SOIL: ML Test End Date: 6/25/2021 CLIENT: Mason Architects Inc. Date Reported: 7/1/2021

SAMPLE OR TRIAL NO. 1 2

MOISTURE TIN NO. N/A N/A

WT WET SOIL +TARE (g) 22.56 22.59 WT. DRY SOIL + TARE (g) 21.00 21.09

WT. MOISTURE TIN 15.50 15.67

WT. WATER (g) 1.56 1.5 WT. DRY SOIL (g) 5.50 5.42

MOISTURE CONTENT (%) 28.36 27.68

Plastic Limit = 28 %

SAMPLE OR TRIAL NO. 1 2 3

MOISTURE TIN NO. N/A N/A N/A

WT WET SOIL +TARE (g) 11.00 11.73 9.95 WT. DRY SOIL + TARE (g) 8.13 8.57 7.34 Wt. Tare (g) 1.78 1.79 1.76 wT. WATER (g) 2.87 3.16 2.61 WT. DRY SOIL (g) 6.35 6.78 5.58

MOISTURE CONTENT (%) 45.20 46.61 46.77

No. of Blows 34 22 16

35-25 30-20 25-15

Liquid Limit = 46 % at N = 25 blows Plasticity Index = 18 %

ATTERBERG LIMITS

PLASTIC LIMIT DETERMINATION

LIQUID LIMIT

Masa Fujioka & Associates

45 46 47