Archaeological inspection and monitoring of the MAPL-WEP Pipeline in Sweetwater and Uinta Counties, Wyoming
Project Name: Midamerican Pipeline/ Western Expansion Project
Location: Wyoming
Rural and/or Urban: Rural
Client: Enterprise Products L.L.P.
Dates: September 2007-July 2008
CRA Project Manager: Ted Hoefer, III
Project Description: CRA of Longmont, Colorado was contracted by Enterprise Products, LLC to conduct an open trench inspection and monitoring along Segment 6 of the MidAmerican Pipeline Company-Western Expansion Project (MAPL-WEP) Pipeline in Sweetwater and Uinta Counties, Wyoming. The work was conducted in compliance with a Memorandum of Agreement between MidAmerican Pipeline Company, the Wyoming BLM, and the Wyoming State Historic Preservation Office dated June 6, 2006.
Numerous sites were located, and a variety of mitigative measures were implemented along the pipeline corridor. These included an erosional treatment plan for site 48SW15859, protective fencing and monitoring for the Overland Trail and the Rock Springs to Vernal Wagon Road, and limited data recovery at sites 48SW16725, and the Maxon Ranch Site (48SW2590).
At the Maxon Ranch site (48SW2590) several new features were discovered. A data recovery plan was created. Some of the tested features were near the surface, and testing was needed to determine if they maintained integrity. Others were found at depth of up to 1.5 meters and required testing to determine their nature. Auger probes were excavated all around the trench feature to determine the extent of the identified dark strata. These probes contained no artifacts, though each probe encountered enough buried charcoal to hint at a buried cultural stratum.
Eight of the 14 features located in the right-of-way and Trench Feature 1 were tested. Two-hundred twelve artifacts were recovered from excavations at Maxon Ranch; 124 flakes, 2 bifaces, 1 tested cobble, and 80 pieces of bone. Eighty five percent of the lithics recovered were located in CRA investigation Area 2. In CRA Investigation Area 1, there was a dispersed lithic scatter that contained very few flakes and no discernable cultural horizons. Three radiocarbon dates were recovered from the site which placed the occupations between 7000 and 2755 years before present. Paleobotanical analysis recovered ancient seeds from the mustard, grass. and sedge families.
The investigations at site 48SW16725 focused entirely around Feature 1, a large basin-shaped feature measuring 7.3 meters from end to end and visible on both walls of the pipeline trench. The site was initially recommended as potentially eligible for nomination to the NRHP since the feature had the dimensions of an Archaic-age house pit with radiocarbon dates that were much older. Collaboration by Linda Scott Cummings at Paleoresearch proved the feature to be between 12200 and 11200 years old. These dates put the feature into the Folsom era where no semi-subterranean dwelling like a pit house has ever been recorded. During the course of investigation it was determined that the feature was not cultural. Bill Eckerle at Western Geoarch conducted a geomorphic analysis that proved the feature to be a small pond or marsh created by a water saturated hillside slumping to create a dam. This led to the site being sampled to document the paleoenvironmental conditions of the Folsom era. Paleobotanical remains recovered from the feature showed a climate during deposition that was significantly wetter than it is today with members of the rose, sunflower, snowberry, and buckwheat families present in an area that is mostly sagebrush and grass today.
