Petaluma will use a $200,000 state grant to focus on catching motorists who drive too fast and who drive under the influence of drugs or alcohol.

The Office of Traffic Safety grant will help fund surveillance equipment, laser radar units, checkpoint supplies and officer overtime, said Petaluma Police Sgt. Ken Savano.

Enforcement operations will include checkpoints, serving warrants and staking out "habitual DUI drivers," court stings, and probation and parole checks, Savano said.

Last year, there were 607 arrests in the city, said Lt. Mike Cook of the city's traffic safety program. This year, he said, it's projected there will be 100 more arrests than that.

In a statement Thursday, police said that over the past three weeks, 15 drivers — three of whom had just caused collisions — were arrested for driving under the influence.

In one case, as police were investigating an accident in which drugs or alcohol were a suspected factor, a 16-year-old girl drove by and crashed into a car. Tests showed that her blood alcohol level was three times the legal limit for a driver over age 21 and she, too, was arrested on suspicion of driving under the influence, Savano said.

- Jeremy Hay