Att - Geotechnical Data Report - HAVO Rainsheds Shear Wave Velocity Survey

August 26, 2024
MFA Project No. 23732-003
Otak, Inc.
11241 Willows Rd NE, Suite 200
Redmond, WA 98052
Attention: David Sacamano, PLA
[email protected]
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

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