Tehipite Chapter of the Sierra Club

Ferguson Slide on Highway 140

by George Whitmore

I was at the meeting of the Mariposa County Board of Supervisors this morning to listen to the Caltrans presentation describing their intentions on the Ferguson Slide. They have two different projects ongoing. One is to provide a temporary solution to enable vehicles up to 45 feet long to travel Highway 140. This would be totally separate from the other project, which would provide a permanent solution. The following comments are regarding the temporary solution. For ease of discussion, I will refer to downstream as being “west” and upstream as being “east”. I realize that the actual compass bearings are different.

Caltrans plans to install two new temporary bridges which would be longer than the existing ones.

On the downstream end of the project, the south end of the new bridge would be where the present temporary bridge abutment is, and the north end would be to the east of the present bridge abutment. Thus, the new bridge would be significantly longer than the existing bridge, increasing the radius of the turns at both ends of the new bridge (compared to the existing bridge). However, the span would still be short enough that it would not require a pier to provide support between the two abutments.

On the upstream end of the project, the south end of the new bridge would be where the present temporary bridge abutment is, and the north end would be to the west of the present bridge abutment. This would be two spans, one of 170 feet and one of 130 feet, connected on a pier. The reason for making one span longer is to move the pier as far away as possible from the main channel of the river. Again, the greater length (compared to the existing bridge) would significantly increase the radius of the turns at both ends of the new bridge. I realize not everyone is into geometry. Longer radius means opening up the curve so it can accommodate longer vehicles. The new bridges would still be single lane, but they would accommodate vehicles up to 45 feet long, whereas the present bridges are restricted to vehicles no longer than 28 feet. The existing one-lane road, which connects the bridges, would be surfaced with additional asphalt to accommodate more traffic and heavier vehicles.

During construction, traffic would continue as at present on the existing bridges. Because the project is between the existing bridges, they anticipate minimal disruption of traffic. In order to expedite construction of the new bridges, removal of the old bridges will be done later, as a separate project. There would be no permanent change in the river corridor. Assuming that there would be a later project to address the problems on a permanent basis, these new bridges would eventually be removed. Since these are considered to be temporary structures to address an emergency, there will not be a full environmental review under NEPA and CEQA. That is, there will be no EIS/EIR.

Caltrans has contractors on tap, ready to start construction as soon as two necessary permits are obtained. These are

(1) A Section 7 determination under the Wild and Scenic Rivers Act. This would come from US Forest Service.

(2) Army Corps of Engineers permit. I think this is because it is a wetland.

Once construction starts, they hope to be done within twelve weeks, hopefully by the end of summer. They probably would work at night in order to expedite construction, and also to minimize impacts on traffic, including rafters. They would not work on big weekends (presumably meaning Memorial Day, Fourth of July, and Labor Day).

They do not anticipate traffic closures except on a very limited basis. Supervisor Fritz had expressed concern that, with the Park Service project at The Narrows having the road totally closed from 10:00 P.M. to 6:00 A.M., if Caltrans closed the road for their project, then El Portal would be totally isolated with no egress/ingress in either direction.

The main concern I heard expressed by citizens was that the project could negatively impact rafting unless construction is put off until later in the summer, when the river is down. (That could happen anyway, if the permits are delayed.)

Since this interim project seems to be consistent with what we had suggested in the past, I decided to make a public statement on behalf of the Tehipite Chapter. My main focus was to thank Caltrans for having listened to the concerns of many people, and for having come up with an interim solution which addresses those concerns. I did not say, “We support the project,” but a listener might have inferred that. Since some of the people in the room knew who I was, as a result of my having been there previously, I thought it would look a little strange if I chose to have no comment. Interestingly, the Caltrans District 10 Director (Kome Ajise, Stockton) came up to me afterwards and appeared interested in having further communication.

Caltrans also commented on the permanent project, but–in the hope of minimizing confusion–I will not report on that in this message.