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Preliminary Report for Data Recovery at Site BK -2-062518 Colowyo Coal Company <br />1.0 INTRODUCTION <br />Colowyo Coal Company L.P. (Colowyo) is constructing a culvert as part of the haul road <br />associated with their Collom Expansion Project (Project). As part of the Project, Tetra Tech has <br />been contracted to provide archaeological monitoring services for Elk Ridge Mining and <br />Reclamation (Elk Ridge) on the behalf of Colowyo. The High Potential Area (HPA) archaeological <br />monitoring has been conducted in accordance with Exhibit 5, Item 3- Cultural Resource Protection <br />Plan (Permit No. C-1981-019). <br />On June 25, 2018 Tetra Tech's cultural resource monitor observed a thermal feature <br />approximately 20 cm below surface within a proposed culvert location within the haul road <br />immediately east of County Road 51 (Figures 1 and 2). In accordance with Exhibit 5, Item 3; <br />ground stripping activities were stopped within 100 feet (ft) [30 meters (m)] and the site was <br />flagged for avoidance. Tetra Tech produced a notification report for Colowyo to submit for review <br />to OSMRE; Colorado Division of Reclamation, Mining, and Safety (DRMS); and Office of <br />Archaeology and Historic Preservation (OAHP). The site could not be avoided by the Project and <br />faces complete removal as part of construction activities. OSMRE in consultation with DRMS and <br />OAHP determined the Project would cause the site an adverse impact and requested the <br />development of a historic properties treatment plan (HPTP). The identified adverse effects would <br />be the destruction of the data potential documented at the site in the form of man-made features <br />and additional subsurface potential. Tetra Tech produced the HPTP and Tri-State on behalf of <br />Colowyo submitted it to OSMRE and OAHP for review. Both agencies provided their concurrence <br />with the HPTP on July 2, 2018. <br />The field work portion of the HPTP was executed by Tetra Tech from July 16 to 17, 2018. The <br />following preliminary report is to provide OSMRE, DRMS, and OAHP the information needed to <br />concur field work efforts are completed, information potential has been exhausted, and Colowyo <br />can proceed with construction activities within the Site BK -2-062518 boundaries prior to <br />completion of the laboratory analysis and final technical report. <br />2.0 DATA RECOVERY FIELD WORK RESULTS <br />The executed field work conformed to standard archaeological practices intended to yield <br />information in support of the research design detailed in the HPTP (Karpinski 2018). The field <br />work tasks were to A) recover potential data within the identified features; and B) determine if any <br />additional subsurface component material remains; and C) identify what, if any, taphonomic <br />processes have impacted the cultural component(s). <br />2.1 Feature Data Recovery and 1 by 1 m Units <br />An electronic 1 by 1 m site grid with a primary datum was established over the site. Individual <br />units, surface artifacts, and features were point plotted using a GeoExplorer 6000 series GeoXH <br />using UTMs coordinates recorded in NAD83, Zone 13 North. Within each unit, provenience was <br />recorded using a sub -datum (usually southwest corner of the unit), string, line level, and tape. <br />One feature (Feature 1) was identified during site discovery and one additional feature (Feature <br />2) was identified during data recovery efforts (Table 1). One 1 by 1 m unit was established to <br />facilitate Feature 1 data recovery. The 1 by 1 m unit was used to maintain horizontal and vertical <br />control during data recovery. Feature 2 was observed exposed in the mechanical cut wall profile <br />at the Limit of Disturbance. Horizontal and vertical control was maintained using the north to south <br />oriented wall cut and no 1 by 1 m unit was established. Feature data recovery was conducted as <br />outlined in the HPTP (Karpinski 2018). <br />Tetra Tech July 2017 <br />