B08_Att_(3)_2024_08_26_-_Geotechnical_Data_Report_-_HAVO_Rainsheds_Shear_Wave_Velocity_Survey.pdf

August 26, 2024 MFA Project No. 23732-003

Otak, Inc.

11241 Willows Rd NE, Suite 200 Redmond, WA 98052

Attention: David Sacamano, PLA David.Sacamano@otak.com

Subject: Geotechnical Data Report – ReMi Shear Wave Velocity Testing Task Order 140P2024F0173 Rehabilitate Water Treatment System Hawaii Volcanoes National Park

Volcano, Hawaii Island, Hawaii

Masa Fujioka & Associates (MFA) is pleased to submit this Geotechnical Data Report for the subject project. This report presents the results of refractive microtremor (ReMi) shear wave velocity testing conducted at the project site. Our interpretation of the ReMi data and pertinent recommendations are included herein:

Scope of Work

We proposed to perform seismic shear wave velocity testing to maximum depths of 100 feet below ground surface (bgs) using ReMi methods. The survey data was used to generate 1-dimensional depth vs shear wave velocity profiles for the project site to supplement data from our forthcoming geotechnical field investigation.

Refraction Microtremor (ReMi) Survey

The refraction microtremor—or ReMi survey, is a survey method used to measure and analyze Rayleigh seismic waves. The Rayleigh waves, which are generated by seismic energy sources such as nearby pedestrian and vehicular traffic, nearby construction activity, wind, and other passive or active seismic energy sources, are collected by a seismograph connected to a linear seismic recording array consisting of 12 geophones either placed directly on hardscaped ground surfaces, or embedded into surface soils.

The geophones measure the transverse component of the seismic waves, or shear waves, as they refract through the subsurface soil or rock materials. As shear wave velocity is a mechanical property related to a subsurface material by the ratio of the material’s shear modulus to its density, the velocity can be used to identify layers of lower or higher density materials beneath a site.

On August 5, 2024, MFA performed a site visit and conducted shear wave velocity surveys of the project site. The surveys were performed in general accordance with American Society for Testing and Materials (ASTM) Method D5777 - Standard Guide for Using the Seismic Refraction Method

Geotechnical Data Report August 26, 2024 Task Order 140P2024F0173 Rehabilitate Water Treatment System MFA Job #24732-003 Page 2 for Subsurface Investigation. The data was measured using a Seismic Source DAQLink 4 seismograph and an array of 12 geophones spaced at intervals of up to 26.2 feet, or up to 288 feet in total.

Results and Data Analysis

MFA performed ReMi surveys at five (5) locations. Two (2) ReMi survey lines were performed for the purpose of generating 1-dimensional shear wave velocity profiles and to assist in determining seismic site classification. Three (3) ReMi survey lines were performed to collect data for the purpose of generating 2-dimensional shear wave velocity profiles and to aid in identifying potential voids in the site subsurface in a limited portion of the site. The seismic recording array locations are presented in Figure 1 – Shear Wave Survey Plan.

1-Dimensional Shear Wave Velocity and Seismic Site Classification

For 1-dimensional shear wave profiles, the geophones were spaced at approximate 26.2 foot intervals, for a total array length of approximately 288 feet. An average of the shear wave velocity data across the twelve geophones was collected and analyzed using ReMi 1dS 2.1.0 software, and spectral energies were plotted as the inverse of shear wave velocity versus frequency. The highest shear wave velocity at each frequency was “picked” to produce a dispersion curve, which was processed using VsSurf ReMi 2.1 software to produce corresponding plots of the average shear wave velocity versus depth across the ReMi path versus depth.

In general accordance with requirements of American Society of Civil Engineers (ASCE) and Structural Engineering Institute (SEI) standard ASCE/SEI 7-22 – Minimum Design Loads and Associated Criteria for Buildings and Other Structures., the data results were used to provide an average shear wave velocity over the entire length of each ReMi array for the upper 100 feet of the site subsurface (vS100), and determine a seismic site classification.

In general, shear wave velocities were recorded at approximately 1,048 to 1,624 feet per second (ft/s) within the top 100 feet of the site subsurface under ReMi line 1, and from 860 to 1,370 ft/s under ReMi line 2. Publicly available geologic information indicates that the project site is underlain by previous lava flows from the Puna volcanic series.1 Variability in the shear wave velocities may be attributed to the presence of less dense near-surface materials, voids such as lava tubes or fissures, differences in rock structure, or rock subjected to different stages of weathering, or the presence of tephra deposits from previous volcanic activity near the site.

The average shear wave velocity determined from our ReMi testing ranged from 1,214 to 1,317 ft/s which is consistent with Seismic Site Class CD as defined by ASCE/SEI 7-22. The corresponding resultant Vs100 are presented in Table 1 below, and shear wave velocity versus depth plots for ReMi survey lines 1 and 2 are presented in Figure 2 and Figure 3, respectively.

1 Wolfe, E.W. and Jean Morris. 1996. Geologic Map of the Island of Hawaii. [with accompanying text, I-2524-A]. United States Geological Survey.

MFA Job #24732-003 Page 3

Table 1. Average shear wave velocity and seismic site classification per ReMi survey line

ReMi Line Average Shear Wave Velocity - 100 Feet bgs vS100 (feet/sec)

1 1,317

2 1,214

2-Dimensional Shear Wave Velocity

MFA conducted an additional shear wave velocity survey for the purpose of obtaining a 2-dimensional profile at the site. The survey combined data from three overlapping seismic recording arrays, each measuring approximately 110 feet in length. An MFA subconsultant performed analysis of the shear-wave velocity and thickness of subsurface layers at locations along the length of each of the survey path, generating 1-dimensional and 2-dimensional shear wave profiles for depths up to 30 feet bgs for that portion of the site. Our subconsultant’s report, including the 1-dimensional and 2-dimensional profiles is presented as Appendix A – 2D Shear Wave Analysis.

The 2-dimensional plot indicated a 5-foot thick layer with shear wave velocity of 650 ft/s. The velocity gradually increases to 960 ft/s at a depth of 12 feet bgs. A high velocity, 1200 ft/s layer is seen in the profile, 5-7 feet in thickness, present near the northwest end of the survey path. A similar thickness high velocity layer towards the southeast end of the survey path suggests that this layer is a previous lava flow containing a basalt boulder. At approximately 20 feet bgs, the shear wave velocity decreases to between 800 to 960 feet/s.

MFA Job #24732-003

LIST OF ATTACHMENTS

Figure 1 Shear Wave Survey Plan

Figure 2 1-Dimensional Shear Wave Velocity Profile – South Array

Figure 3 1-Dimensional Shear Wave Velocity Profile – North Array

Appendix A 2D Shear Wave Analysis Report

HAVO Rehabilitate Water Treatment System

Source: Esri, Maxar, Earthstar Geographics, and the GIS User Community 0 250 500

Feet

Notes:

1. Locations acquired using handheld GPS device and are considered approximate.

Hawaii Volcanoes National Park Hawaii Island, Hawaii

Figure 1 Shear Wave Survey Plan

MFA Project No:

Approved By:

Drawn By:

Drawn Date:

24732-003

RTI

EN

8/2024

Service Layer Credits: Pictometry, 2013

Project Location

Array 1Array 1

Legend Survey Path for 2-Dimensional Profile

North Middle South

Survey Path for Seismic Site Classification Array 1 (South) Array 2 (North)

Array 2Array 2

2-D North2-D North

2-D Middle2-D Middle

2-D South2-D South

Vs100 : 1,317 ft/s

Shear Wave Velocity 1-Dimensional Profile ReMi Array 1

Hawaii Volcanoes National Park - Volcano, HIMFA Project Number 24732-003

Figure 2

0 500 1000 1500 2000 2500 3000 3500

D ep th (f t)

Shear Wave Velocity (ft/sec)

Vs100 : 1,214 ft/s

Figure 3 Shear Wave Velocity 1-Dimensional Profile ReMi Array 2

Hawaii Volcanoes National Park - Volcano, HIMFA Project Number 24732-003

0 500 1000 1500 2000 2500 3000 3500

D ep th (f t)

Shear Wave Velocity (ft/sec)

MFA Job #24732-003

Appendix A

2D Shear Wave Analysis Report

Shear-Wave Velocity Report Terēan VsSurf ReMi™ 2.1 Software

Array Location Site Name: HAVO Rainshed

Survey Parameters Geophone Count: 12 Geophone Spacing: 10 ft Array Length: 110 ft Survey Date:

Performed By: Masa Fujioka Analysis By: Alison Starr Analysis Date: Mon Aug 12 13:05:41 PDT 2024

Narrative

SHEAR WAVE VELOCITIES AND SEISMIC SITE CLASS

Masa Fujioka’s geophysical site evaluation included subsurface seismic imaging using Terēan’s VsSurf ReMi™ seismic data processing software. Seismic surveys were performed to determine subsurface conditions. The surveys were performed by recording active and/or ambient (passive) seismic sources.

The seismic recording array for these surveys consisted of combining three 12, 4.5 Hz geophones at 10 ft spacing, for a total survey length of 250 feet. Noise generated by hammer hits during data acquisition while ambient noise was generated from traffic along the nearby roads. The seismic data were acquired using a ReMiDAQ™ 4-12 channel seismograph, while data was processed using Terēan's ReMi™ software (terean.com/products).

Depth Vs

(ft) (ft/s)

0.0 443

7.7 443

7.7 1,382

25.6 1,382

25.6 620

30.1 620

30.1 1,430

358.2 1,430

Frequency Slowness (Hz) (s/m)

25.878 0.00599 Seismic File: 0001.sgy

24.902 0.00581 Pre-Processing: preprocess

24.414 0.00543 Surveyed Geophones: No

23.437 0.00506 Max Frequency, Hz: 50

22.460 0.00468 Min Velocity, m/s: 107

21.484 0.00449

20.507 0.00412

19.042 0.00393

17.089 0.00393

15.625 0.00393

13.671 0.00356

12.207 0.00356

10.742 0.00337

9.766 0.00318

8.301 0.00299

6.348 0.00281

29.296 0.00674

31.249 0.00693

33.691 0.00693

35.156 0.00712

37.597 0.00749

41.015 0.00749

43.945 0.00768

48.339 0.00787

49.804 0.00787

Terēan ReMi™ 2dS Analysis and Results

Masa Fujioka collected three 110 ft long seismic lines to image the northeastern portion of the HAVO Rainshed site from northwest to southeast. Terēan performed a two-dimensional analysis on each 12-channel array and combined them, resulting in a 250 ft long 2dS section.

The 2d analysis used the same seismic data as the 1d analysis above. The 2d section extends to a depth 30 ft below the ground surface. The shear-wave velocities in the section closely follow the velocities in the 1d results above. A 5 ft thick low velocity layer (Vs 560 ft/sec) gradually increases to Vs 960 ft/sec. At ~12 ft depth, a high velocity (Vs 1200 ft/sec) 5-7 ft thick layer is visible to 75 ft into the northwestern portion of the array. The presence of a similar thickness, high velocity layer at array distance 175-220 ft suggests that this high velocity layer is lava flow with a basalt boulder. At ~20 ft depth, the velocities decrease again to 800-960 ft/sec.

NW SE