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330 Land Company, LLC Arroyo Lago 9785.004.001 Design-Level Geotechnical Report Page | 2 April 16, 2024 Latest Revision October 31, 2025 • Treadwell & Rollo. 2007. Due Diligence Investigation – Parcel 2 and Parcels D through G, Hanson Radum Site, Pleasanton, California. May 25, 2007. Project No. 4490.01 • Treadwell & Rollo. 2009. Geotechnical Investigation Pleasanton Land Development Project, Pleasanton, California. September 8, 2009. Project No. 4490.02. Additionally, we previously prepared the following geotechnical report for the property and the greater East Pleasanton Specific Plan (EPSP) area. • ENGEO. 2020. Ground Improvement Summary, East Pleasanton Specific Plan, Pleasanton, California. October 21, 2020. Project No. 9785.001.001. • ENGEO. 2023. Preliminary Geotechnical Report, Arroyo Lago, Pleasanton, California. May 18, 2023. Project No. 9785.004.001. • ENGEO. 2024. Geotechnical Feasibility Report, Arroyo Lago – Infrastructure Area, Pleasanton, California. February 12, 2024, Revised March 12, 2024. Project No. 9785.004.003. This report was prepared for the exclusive use of 330 Land Company, LLC and their consultants for the planning and preliminary design of this project. In the event that any changes are made in the character, design, or layout of the development, we must be contacted to review the conclusions and recommendations contained in this report to evaluate whether modifications are recommended. This document may not be reproduced in whole or in part by any means whatsoever, nor may it be quoted or excerpted without our express written consent. 1.2 PROJECT LOCATION The project site is generally located northwest of the intersection of Busch Road and El Charro Road in Unincorporated Alameda County, California (Figure 1). The approximately 26.6-acre site is a portion of the parcel identified by Assessor’s Parcel Number (APN) 946-1250-6-4. The site is bounded by Busch Road to the south, existing residential properties to the west, an Alameda County Flood Control easement to the north, Lake I further north, and vacant open space to the east. The site is currently occupied by light seasonal vegetation. A PG&E easement extends east-west on the northern side of the site, and a dirt road runs north-south through the center of the site. According to the grading plans prepared by CBG dated July 2025 and a recent site visit, the site gently slopes inwards towards the central-eastern portion of the property, with the high point in the northwest at approximately Elevation 362 feet (NAVD88) and the low point in the central-eastern portion of the site at approximately Elevation 357 feet. An emergency drainage swale was constructed in 2023 that runs from the northwestern corner of the site at approximately Elevation 357½ feet to an earthen channel outfall located at the south-eastern site boundary at Elevation 355½ feet. The swale has a base width of approximately 4 feet and 4:1 (horizontal:vertical) slope.