CARY, N.C. — A California-based engineering firm has been hired to investigate a sewage spill that sent almost 8 million gallons of untreated wastewater into Swift Creek.

Cary officials said Monday they have hired Brown and Caldwell to assess the June spill, which occurred when heavy rains and erosion dislodged a pipe at the Swift Creek Regional Pump Station.

The town shut down the pump station for several days. After waste initially flowed into the creek and downstream into Lake Wheeler and Lake Benson, the town launched a round-the-clock trucking operation to transport the waste to a nearby treatment plant.

Brown and Caldwell will be paid up to $200,000 to provide an accurate, detailed evaluation of the events leading up to the June 23 spill and the response by the town and private contractors. The company also will make specific recommendations on how to prevent such spills in the future.

Last month, Town Manager Bill Coleman said an initial evaluation by Black & Veatch, the engineering firm handling the expansion at the Swift Creek pump station, wasn't specific about the reasons the pipe dislodged and provided only generic recommendations.

Coleman said he expects the Brown and Caldwell analysis to be complete within six weeks.