Rhode Island’s second oil spill in a month was quickly contained when the state Department of Environmental Management and a private cleanup firm installed booms in the Chepachet River and placed absorbent pads downstream. The action kept the oil from fouling trout waters down river. Officials said it was too early to assess the impact of the spill of about 100 gallons of what appeared to be No. 2 heating oil on the river in north-central Rhode Island. Nor were they certain if the leak came from above- or below-ground storage tanks. On June 23, about 300,000 gallons of No. 2 heating oil spilled into Narragansett Bay when the Greek-registered tanker World Prodigy ran aground off Newport.