Orinda reached a critical compromise agreement with the Regional Water Quality Control Board that should speed the progress of repairs to the Miner Road sinkhole.
A number of permits are still required, but that from the RWQCB is the most important and now more likely, owing to the city's agreement to increase the height of the reinforced concrete culvert by a half foot to provide better fish passage.
According to Orinda Public Works Director Larry Theis, the culvert will remain at 16-feet wide but the height will go from seven to seven-and-a-half feet. The additional half foot will be buried with channel soil, which fish reportedly prefer to concrete; the soil also reduces the water velocity through the culvert.
RWQCB wanted even more depth, but every inch increase affects a lot of other things in the design, Theis said. This design change does not affect the culvert's flood capacity, which was a matter of concern to the neighboring homes. Theis also said that the compromise, reached March 30, took longer than Orinda wanted, as the city and RWQCB went back and forth on the issue. Based on the new final design, the city must obtain permits from all the regulatory agencies, including the Army Corps of Engineers and the California Department of Transportation.
The city is now making the necessary modifications to the engineering plans so that the final permit applications can be submitted. The design will also be reviewed by the contractor for a new cost estimate, which can then be submitted to Caltrans, along with the plans, for the city's official funding request.
The city continues to coordinate its work with the utilities during the construction of the sinkhole repair. EBMUD wants to turn the existing water mainline back on before April 10. That agency is expected to work with the city to either repair leaks so the mainline can be put back in service or to make other arrangements to ensure there are no service disruptions.
Contractor Chrisp Company is nearing completion of the centerline and edgeline striping along the Camino Sobrante and Manzanita Road detour routes. Theis says the remaining striping should be complete soon.