El Portal Road Reconstruction Project Geotechnical Borings

This project proposes to drill up to thirty (30) geotechnical borings in support of design development for the El Portal Road Reconstruction Project in the location known as "The Narrows." The purpose of these borings will be to determine the subsurface soil and bedrock depth and composition in the previously disturbed portions of the roadway where it is being undermined by the Merced River. A combination of engineering solutions will be applied to reconstruct the road within the project area, which necessitates the proposed number of borings in different locations. Borings will be 4 inches in diameter, approximately 25 feet deep, and located within the shoulder and/or slope of the roadway nearest the Merced River in order to determine how deep footings for retaining walls (used to support the reconstructed roadway) will need to be located.

One lane will be closed during drilling operations with no more than 15 minute delays, due to use of a truck-mounted drill rig. Drilling fluids will be contained and transported off site. Night work may occur (which is preferred) and no work will occur on weekends or any holidays. Borings will be backfilled with gravel and capped with asphalt. Total estimated time for geotechnical work is one week. Consultation with cultural resources staff indicates there is no archeological, traditional gathering, or cultural landscape impacts from these activities.