Article Title

Archeological Survey of the Loop 20 Improvement Project Webb County, Texas

Authors

Christopher Ringstaff

Agency

Texas Historical Commission

Abstract

The proposed Loop 20 Project is a new location roadway in southwestern Webb County originating at the intersection of Loop 20 and US 59 and ending at the intersection of Loop 20 and International Blvd. The Area of Potential Effect (APE) has a calculated length of approximately 7.8 miles with a total area of approximately 378.2 acres. The project consists of approximately 7.4 miles of new Right of Way (ROW) immediately adjacent to the existing Loop 20 ROW. The typical existing ROW width is 175 feet with a proposed addition of 225 feet for a total width of 400 feet. The area of the existing ROW is approximately 165.5 acres with a proposed addition of 175 acres of new ROW for a total of 340.5 acres. The typical depth of impact will be approximately 3 feet for the roadway construction and 6 feet for culverts.

The Loop 20 Project was conducted by a TxDOT archeologists between May and June (May 27-29 and June 16-18), 2015. Utilizing GIS, the project area was divided into high and low probability areas which shaped field methods accordingly. A total of 42 shovel tests were excavated in the high probability areas. Several parcels of the APE were inaccessible due to denied of Right of Entry (ROE). These parcels have a combined area of approximately 69.9 acres. All but one are within the defined low probability area and will not require survey due to extensive land-use impacts. The area of denied ROE within the high probability area consists of approximately 5.9 acres and will require survey once access is acquired.

The survey identified five previously recorded sites designated 41WB357, 41WB358, 41WB359, 41WB360, and 41WB367. All of the sites consist of prehistoric lithic scatters of burned rock and debitage representing either open campsites, lithic procurement sites, or both. Only sites 41WB358 and 41WB367 provided temporal diagnostic artifacts suggesting a late Archaic age for both. The remaining sites are of unknown prehistoric age. Due to ROE agreements, no artifacts were collected during the survey. Three of the five sites, 41WB357, 41WB358, and 41WB359, are considered potentially eligible for listing to the NRHP and for designation as a SAL and will require additional investigation.

As for additional survey or testing, the aforementioned 5.9 acres with denied ROE and immediately south of 41WB359 will require survey. Based on observed features and the potential for (albeit shallow) burial, sites 41357, 358, and 359 are recommended for NRHP/ SAL testing. Due to the absence of features, lack of deposition, and prior construction impacts, no further work is recommended at the two remaining sites 41WB360 and 41WB367 as they both lack sufficient integrity of location, association, and materials to be able to address important questions of prehistory or history and are not considered eligible for listing to the NRHP and for designation as a SAL.

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