Supervisors authorize slope and drainage improvements for Rainbow Crest Road and Rainbow Heights Road

The San Diego County Board of Supervisors approved the advertisement for bid and subsequent award of a construction contract for drainage improvements along Rainbow Crest Road and Rainbow Heights Road.

The supervisors’ 5-0 vote Feb. 26 also appropriated $1,390,000 of available balance from the road fund of the county’s Department of Public Works for the project involving the west side of Rainbow Crest Road north of Rock Ridge Drive and the west side of Rainbow Heights Road between branches of Select Way. The supervisors’ action also found the project categorically exempt from California Environmental Quality Act review.

“Over a period of years, winter storms critically reduced the stability of the slopes along Rainbow Crest,” said Supervisor Bill Horn. “Staff closely monitored the slope and designed a retaining wall that will ensure safety on the road and for nearby residential homes.”

Rainbow Crest Road is a narrow two-lane road which was cut into a steep slope. During the December 2010 storms, a 40-foot section was heavily damaged when slope failure underneath the roadway caused the outside lane to wash out, which left only one lane open to traffic.

The county declared a proclamation of local emergency due to the December 2010 storms, and the Department of Public Works issued emergency contracts to repair roads and culverts and to remove debris. The repair work design was expedited, and in May 2011 the county supervisors authorized a construction contract for repairs to Rainbow Crest Road which included building a wall to fortify and stabilize the slope at the failure location as well as reconstructing the outside lane.

Since the completion of that emergency repair work, DPW staff has monitored the slope regularly to ensure that its overall integrity is being maintained. The design plans for a longer-term solution were completed. A retaining wall will repair the existing slope, which will also improve drainage and reduce the potential of future flooding as well as reducing the risk of additional failures. A retaining wall and drainage improvements will also be constructed along Rainbow Heights Road.

“We’re expecting the wall to be in place by fall 2014,” Horn said.

The construction is expected to begin this spring. Traffic control measures during construction will limit impacts to the community. The construction will take place both on public right-of-way and on private property, and temporary access rights for the private property have been obtained. On Jan. 15, the Rainbow Community Planning Group endorsed the project with a 9-0 vote.