Caltrans Work on El Camino at Maple

June 12, 2019

Town Public Works staff have been coordinating with Caltrans for the repair of a sinkhole that has been developing at the El Camino Real/Maple Avenue intersection. However, Caltrans has authority over the roadway, the closure, and the ultimate repair.  

In response to a Town alert, Caltrans initially responded by placing temporary paving in the hole that had developed at the site. In April 2019, Caltrans sought out information relating to the utilities in the area. On May 25, as the sinkhole began to expand into the first southbound through travel lane, Town Public Works crews were dispatched to place temporary traffic controls at the location to secure the area. Caltrans was again advised of the expanding situation. 

On May 31, Caltrans conducted a site visit to investigate the sinkhole, took control of the site and supplemented the Town's temporary controls with a more robust closure of the affected area. Town staff assisted Caltrans in contacting the various utilities (West Bay Sanitary, Calwater, AT&T, etc.) to provide information regarding their systems in the area. Caltrans followed up by calling in an Underground Service Alert (USA) request for utility markings. 

During the week of June 3, Caltrans began excavation of the sinkhole area to determine the cause and uncovered a large cavity under the pavement. The cause of the cavity was not evident, although moisture was detected when Caltrans probed the underlying materials and water was found in the adjacent telecommunications manhole. Caltrans has taken water samples to assist in determining the origin of the water intrusion. 

The area is currently covered with steel plates and the affected lanes (both turn lanes and the southbound through lane) remain closed. Caltrans is monitoring the situation and awaiting water test results. Caltrans has not advised the Town of when they might be returning to complete the excavation and repair of the sinkhole. Town Public Works staff check in with Caltrans on a regular basis for updates. 
 
George Rodericks
City Manager
grodericks@ci.atherton.ca.us