OAKLEY -- With some calling the overhaul of Oakley's downtown shopping center and adjoining streets the most complicated project the city ever has undertaken, council members have authorized more than $670,000 in additional construction costs.

On Tuesday, they unanimously approved 15 change orders that have occurred so far during the renovation of Main Street's Oakley Plaza. These revisions to the work described in contractors' original construction contracts amount to $677,714, which brings the cost of the project to just over $6 million.

The undertaking involves repaving the plaza's entire parking lot and adding parking behind one of the two newly constructed restaurants, as well as narrowing the section of Main Street that runs along the front of it.

Three contractors and multiple subcontractors are working on the project that three additional firms designed; the sheer number of parties involved meant they weren't always in sync with each other, and that's caused construction delays that can be measured in money, Mayor Kevin Romick said before the meeting.

In addition, architectural and engineering mistakes have been made, he said -- "and I'm sure there are plenty of problems we created on our own."

When the plaza is finally finished, Romick suggested holding a "postmortem" with the companies involved to analyze what went wrong so the city can be better prepared for future large-scale endeavors.

City Engineer Jason Vogan declined to elaborate on a mention in his staff report that the city is withholding fees from members of "the design team" while officials discuss the errors with them.

One change order was to pay a paving and grading contractor overtime to install utilities so restaurants would have electricity when they were ready to open. Another enabled the same company to be paid $62,134 for doing extra jobs that cropped up unexpectedly along the way.

Not only did design errors increase the cost of the work on the plaza, but they made it more expensive to build Carpaccio Ristorante at Vintage Parkway and Main Street.

As such, the council in a separate action voted to add $160,000 to restaurant owner Manuel Muñoz's indebtedness.

Starting next month, Muñoz will have to pay $859 more per month to repay the 30-year loan, which the city made from its reserves at a 5 percent interest rate.

He already has a $1.2 million loan and another for $600,000 that's forgivable after 10 years of operation.

But not all the change orders represented cost overruns. Some occurred because the city had one contractor do work that originally was going to go to another for the sake of speeding up the job.

The biggest was a $1.5 million change order allowing the city to add two projects to the work a contractor already had agreed to do after clarifying the scope of the jobs -- jobs that were going to be done by some builder anyway.

In related news, the council settled on the design of a fountain that's planned for the entrance to Oakley Plaza. The decision came after council members decided the $421,000 price tag of a model that was included in the landscaping bid they accepted was too high.

Presented with three options, council members decided to go with an approximately $210,000 "double bowl" decoration -- a two-tiered fountain with a single jet that would send water splashing into and over the bowls onto a concrete slab that's flush with the surrounding pavement. The fountain would come with four lights that could be manually adjusted to beam different colors and will have a large underground reservoir, not only to recirculate the water but to replenish at least some of what evaporates by collecting rain water.

Reach Rowena Coetsee at 925-779-7141. Follow her at Twitter.com/RowenaCoetsee.