GEOLABS, INC. Geotechnical Engineering and Drilling Services

2006 Kalihi Street • Honolulu, Hawaii 96819 Phone: (808) 841-5064 • Facsimile: (808) 847-1749 • E-mail: hawaii@geolabs.net Hawaii • California

August 13, 2015 W.O. 5822-60(A) Mr. Craig Arakaki Engineering Concepts, Inc. 1150 South King Street, Suite 700 Honolulu, HI 96814

GEOTECHNICAL ENGINEERING STUDY UNIVERSITY OF HAWAII WEST OAHU – ROAD “B”

EWA, OAHU, HAWAII Dear Mr. Arakaki: In accordance with our fee proposal dated July 18, 2014, this letter report provides geotechnical engineering recommendations for the University of Hawaii West Oahu – Road “B” project located in the Ewa area on the Island of Oahu, Hawaii. The project location and general vicinity are shown on the attached Project Location Map, Plate 1. This letter report summarizes the findings from our site reconnaissance and desk-top study, and presents geotechnical engineering recommendations for the proposed project. The findings and recommendations presented herein are subject to the limitations noted at the end of this letter report.

PROJECT CONSIDERATIONS The University of Hawaii West Oahu Campus covers approximately 103.5 acres and is south and east of Farrington Highway and west of Kualakai Parkway in the District of Ewa on the Island of Oahu, Hawaii. A new roadway, Road “B,” is planned extending from Kualakai Parkway to Kaloi Gulch adjacent to the UH West Oahu Campus. The limits of the project site are shown on the attached Site Plan, Plate 2. Mass grading for portion of the road near the cul-de-sac adjacent to Kaloi Gulch was done previously during the construction of the UH West Oahu Campus but the road construction was not completed. Geolabs observed the earthwork construction and tested the fills during placement. In addition, settlement monitoring of the deep fills placed in Kaloi Gulch at the end of the cul-de-sac was performed as described in our report entitled “Settlement Monitoring Report, University of Hawaii West Oahu Campus – Phase 1, Ewa, Oahu, Hawaii” dated April 12, 2012.

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GEOLABS, INC.

Hawaii • California

A 12-inch water line was previously installed along Road “B”. The area along the existing water line was covered with a layer of recycled asphalt concrete. Based on the available drawings, new utility lines consisting of sewer, drain, water, and recycled water are planned along the new roadway. Previously, a geotechnical engineering exploration was performed for Road “B” and geotechnical engineering recommendations were provided in our report entitled “Geotechnical Engineering Exploration, University of Hawaii West Oahu, Driveway “B,” Ewa, Oahu, Hawaii” dated February 11, 2011. This letter report is to update our previous report above. Borings were not drilled for this study. Evaluations were conducted based on the site observations and available subsurface information only.

PURPOSE AND SCOPE The purpose of our geotechnical engineering study was to utilize available in-house subsurface information to develop a soil/rock data set to formulate geotechnical recommendations for the planned road construction. To accomplish this, a program consisting of the following tasks and work efforts were performed:

1. Review of readily available soils report, field reports, and other information in the project vicinity.

2. Performance of a site reconnaissance and hand probing to evaluate the

present condition of the road subgrade soils.

3. Preparation of this letter report summarizing our work on the project and presenting our findings and recommendations.

4. Coordination of our overall work on the project by our project engineer.

5. Quality assurance of our work and client/design team consultation by our

principal engineer.

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

SITE OBSERVATIONS

The UH West Oahu – Road “B” project site is south and east of Farrington Highway and west of Kualakai Parkway. Presently, the site is vacant and covered with wild grasses and recycled asphalt concrete along the existing 12-inch water line.

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GEOLABS, INC.

Hawaii • California

Substantial shrinkage cracks were observed at the ground surface within the project site. Surface cracks up to about 1 inch wide and from about 24 to 30 inches deep were observed. Photographs of the project site are presented on Plates 3.1 and 3.2. Based on the topographic map provided, the existing ground surface generally slopes toward the center of the new roadway at about twenty five horizontal to one vertical (25H:1V) to 35H:1V inclination. The existing ground elevation ranged from about Elevation +128 to +134 feet Mean Sea Level (MSL).

DISCUSSIONS AND RECOMMENDATIONS The purpose of this geotechnical engineering study was to evaluate the existing conditions at the University of Hawaii West Oahu - Road “B” project site and provide geotechnical recommendations for the project. Site observations and hand probing were made at the site and review of available subsurface information was performed.

Detailed discussion of these items and our geotechnical recommendations for the design of site grading and utility trenches for the new roadway project are presented in the following sections herein. Hand Probings Hand probings with a 5/8-inch diameter steel rod were performed along the new roadway to determine the condition of the roadway subgrade. The depths of penetration of the steel rod ranging from about 1 to 4 inches were measured during the hand probing. Hand probe penetrations of up to 18 inches were measured within the existing surface cracks. Site Grading Based on our site observations, most of Road “B” has not been mass graded. A thin layer of recycled asphalt concrete has been placed over the existing subgrade along the existing 12-inch water line. At the cul-de-sac area at the end of Road “B”, fills have been placed within Kaloi Gulch.

Based of the results of the probing and our site observations, the existing clayey subgrade soils have been exposed to the elements and are relatively loose at the ground surface. These clayey subgrade soils have undergone shrinkage and swelling with the changes in moisture content. Wide and deep shrinkage cracks were noted at the project site. Based on our study, we recommend that the existing clayey subgrade soils be properly prepared and moisture-conditioned prior to fill placement. The site grading recommendations in our report entitled “Geotechnical Engineering Exploration, University of Hawaii West Oahu, Driveway “B,” Ewa, Oahu, Hawaii” dated February 11, 2011 should

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GEOLABS, INC.

Hawaii • California

be used. Care should be taken during the site grading work near the existing 12-inch water line to avoid damaging the line.

At the cul-de-sac area at the end of Road “B” where fills have been previously placed, we recommend that subgrade preparation recommendations in the above report be used.

Additional Utility Trenches The installation of new utility lines consisting of sewer, drain, water, and recycled water lines are planned for the project. The utility trench backfill recommendations provided in our previous report dated February 11, 2011 should be used for the installation of the new utility lines.

LIMITATIONS The geotechnical engineering recommendations submitted herein are based upon our desk-top study and visual observations conducted during our site visit. Variations of subsurface conditions anticipated may occur, and the nature and extent of these variations may not become evident until construction is underway. If variations then appear evident, Geolabs, Inc. should be contacted to re-evaluate the recommendations presented in this report. This letter report has been prepared for the exclusive use of Engineering Concepts, Inc. and their client, the University of Hawaii West Oahu for specific application to the University of Hawaii West Oahu – Road “B” project in accordance with generally accepted geotechnical engineering principles and practices. No warranty is expressed or implied. This letter report has been prepared solely for the purpose of assisting the client and design engineers in the design of the project.

University of Hawaii West Oahu – Road “B” Ewa, Oahu, Hawaii

W.O. 5822-60(A) GEOLABS, INC. AUGUST 2015 PLATE 3.1 Hawaii • California

Photograph No. 1: Road “B” with UH West Oahu Campus in background. (8-7-15)

Photograph No. 2: Existing surface crack on surface of recycled asphalt layer. (8-7-15)

University of Hawaii West Oahu – Road “B” Ewa, Oahu, Hawaii

W.O. 5822-60(A) GEOLABS, INC. AUGUST 2015 PLATE 3.2 Hawaii • California

Photograph No. 3: Existing cracks on surface clay soils. (8-7-15)

Photograph No. 4: Road “B” near UH West Oahu Campus. (8-7-15)