Valero is asking the city of Benicia for an OK to begin receiving daily crude-by-rail shipments, including possibly the more volatile oil from the North Dakota Bakken fields. Federal officials issued a warning this year about that fuel after several train explosions, including one that killed 47 people in Canada.

The Valero plan, involving two 50-car trains a day through Sacramento, is among the first of what California officials say is an expected boom in crude-by-rail shipments through the state, prompted by the lower cost of North Dakota and Canadian crude.

The draft environmental report, issued last month by Benicia, included an analysis that says a derailment and spill might happen only once every 111 years. That analysis was authored by a University of Illinois professor, Christopher Barkan, who formerly worked for the American Association of Railroads and does research supported by the association. Barkan, an expert on hazardous rail transport, said in an email that his work for Benicia was not influenced by his association with the railroad association.

Local officials say they plan to issue written responses to that assessment this summer. City of Davis official Mike Webb has challenged the report risk assessment, saying, “It only needs to happen once to be a real problem.”

Also on Friday, a coalition of activists who oppose rail shipments of crude oil called on the state Legislature or the governor to ban or place a moratorium on construction of any more crude rail terminals similar to the one Valero is proposing.

The state Office of Spill Prevention and Response announced it will conduct a series of public workshops later this month soliciting opinions on how it should expand its work to inland areas, including along rail lines. The new state budget includes funding, from oil refinery fees, for the spill office to deal with the expected increase in crude oil shipments by rail. The agency will release information on its “legal and regulations” Web page on Friday.