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CONDOR EARTH 188 Frank West Circle, Suite I l Stockton,CA 95206 209.234.0518 Fax 209.234.0539 CONDORwww.condorearth.com Condor Project No. 2136M October 13, 2023 Jeffrey Wong Lead Senior Registered Environmental Health Specialist San Joaquin County Environmental Health Department 1868 E. Hazelton Ave Stockton, California 95205 Subject: Workplan to Perform Exploration Borings for the Property Located at 800 Mossdale Road, Lathrop, CA 95330 Dear Mr. Wong: Condor Earth (Condor) is pleased to submit the following workplan to perform exploration borings for the Brown Sand Incorporated (Inc.) Mossdale Plant located at 800 Mossdale Road, Lathrop, California (Site). This work plan describes the drilling program procedures, proposed drilling locations, drilling depths, and boring closure procedures. Condor is proposing to advance up fifteen (15) exploration borings on the southwestern portion of the Site, designated as Assessor's Parcel Number 239-040-080 (Figure 1, Attachment A). The purpose of the exploration borings is to evaluate the extent economically feasible resources (sand and gravel)in the subsurface that would be considered for mining future mining operations. This work will be conducted on behalf of Brown Sand Inc. (client). Subsurface Conditions Previous exploratory drillings were conducted in November of 2019 on the parcel adjoining to the southwest of the parcel that is the subject of this workplan. A total of 12 borings were advanced to depths ranging from 56.5 feet below ground surface (feet bgs) to 66.5 feet bgs. The subsurface comprised of primarily lean clay to depths ranging from 25 feet bgs to 40 feet bgs, underlain by primarily well graded sand to the bottom of the boring. Of the 12 borings,the average depth of the clay-sand interface was 36 feet bgs. Groundwater is anticipated to be encountered between 10 to 13 feet bgs, based on the most recent groundwater monitoring report at the Site'. Boring logs and boring locations from the November 2019 drilling event are included in Attachment B. SCOPE OF WORK Task I — Field Work Preparation/Site Coordination Condor will begin fieldwork preparation by marking the proposed drilling area(s) and contacting Underground Service Alert (USA) to verify the locations of utility rights-of-way located at the Site. The project site boundaries will be physically marked so that USA representatives will be able to clear the site for public utilities. ' First Semi-Annual 2023 Compliance Monitoring Report for Compliance with Waste Discharge Requirements,Order No. 115-2011-0008, Period January 2023 —June 2023, Brown Sand, Inc. Prepared by Condor Earth.