 | | | Sinkhole reveals broken culvert that requires a new large diameter pipe to contain major EBMUD water main, PG&E gas pipes, and Contra Costa County Sanitary District sewer pipes. Photo Gint Federas | | | | | | Orinda raced to get sinkhole repairs underway as the unusual closure of Miner Road is adding 20 minutes to the response time for emergency vehicles, including to Sleepy Hollow Elementary School.
City staff has been putting in long hours, including nights and weekends working with potential contractors and government agencies to move forward. One hurdle the city had to clear was convincing the California Regional Water Quality Control Board that their alternate proposal was unworkable and would have added over $400,000 and months of delay.
At a special meeting on Jan. 31, the city council authorized City Manager Janet Keeter to enter into a construction contract with Bay Cities, adding a 20 percent contingency budget. Bay Cities came in with the lowest bid at $1,471,717, and nearly the earliest completion date of March 2. Since the city was able to resolve differences with the RWQCB and pull an emergency permit to begin the work, Bay Cities plans to work two 10-12 hour shifts daily during the peak period of work, weather permitting.
Orinda considered five proposals before accepting Bay Cities' bid. The proposals ranged from similar in time and cost to nearly double the cost and up to 100 working days. Orinda has previously had a good experience working with Bay Cities on the North Lane Storm Water Mitigation Project in 2015, according to council member Amy Worth.
The council had words of high praise for the efforts of the city staff, including Keeter, City Attorney Osa Wolff and especially Public Works Director Larry Theis, who was accepting proposals and vetting them over the weekend after the sinkhole appeared while working around the clock trying to smooth permitting issues. State Senator Steve Glazer, Congressman Mark DeSaulnier and Assembly member Catharine Baker interceded on the city's behalf, and the council expressed its appreciation.
Having investigated several construction options, the city selected an elliptical 10-foot wide corrugated 12-gauge metal pipe for the culvert, which is flattened somewhat to allow for sewage pipes to pass over it, but provides the same flow-through as a 9-foot round diameter pipe, estimated to be sufficient for a 100-year storm. Sewer work is estimated to require $21,000. The RWQCB had advocated for a bigger culvert of the same width as the current 14-foot-wide channel banks, but the city opposed this plan, which might have required further geotechnical studies, expensive pile footings, and perhaps a completely different pipe material. This would have caused extensive delays in an emergency situation. To address RWCQB's concerns, the city agreed to reduce the limits of rock slope protection, to bury the rock under channel substrate, and provide riparian plantings along the bank.
The council also discussed the question of reimbursement for the sinkhole repair. Theis explained that the Federal Highway Administration can reimburse 100 percent of repairs considered emergency opening (EO) but usually only reimburses permanent restoration (PR) at a rate of 88.5 percent, leaving 11.4 percent of the cost to the local authority. Also, improvements, known as "betterments" are generally not reimbursable.
However, Orinda believes that its unique situation should qualify its repairs as EO rather than PR because doing a temporary fix has been determined to provide no benefit but great additional costs. Theis explained to the FHWA and the California Department of Transportation that a permanent repair is necessary now owing to existing site constraints and the lack of any cost effective temporary repair options to reestablish two lanes of traffic. Also, the city believes that widening the pipe in the culvert should not be considered a betterment because it is a necessary safety feature.
Also discussed were traffic calming measures to be put in place quickly, such as lane delineators, and the need for cars to refrain from passing school busses stopped with flashing lights. The city is working with the Orinda Country Club and with neighbors affected by the sinkhole on aesthetic considerations, and is also making riparian habitat and plantings a priority. Theis promised property owners that the city will bring back different options for architectural treatments to the concrete headwalls to maintain the current aesthetics and will obtain both parties agreement to the type of treatment before installation.
Council members Darlene Gee and Dean Orr continue to recuse themselves from the sinkhole discussion because both are regular members of the Orinda Country Club, although neither is on the board, and the club may be affected by the work.
Two members of the public addressed the special meeting. Bob Burt suggested that the city argue that the entire repair should be reimbursable at 100 percent as EO, owing to the emergency nature of the repairs. Dan De Brusschere suggested that the council go ahead without permits, but Attorney Wolff advised against that, although the council took De Brusschere's advice regarding speed seriously and Mayor Eve Phillips explained that the city is moving forward as quickly as possible.
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Lamorinda Weekly, Moraga CA