SAUGUS – An engineering firm hired by the town to oversee a state-mandated massive reduction in raw sewage released into the Saugus River says the project is under budget and ahead of schedule.Paul Ross, an engineer for Camp Dresser & McKee (CDM), said the relining of pipes and manholes have led to the elimination of 36 percent of the 11 million gallons of sewage targeted for removal. According to Ross, much of the water volume was not sewage. Rather, it was groundwater seeping through cracks in the town’s aging pipes.Like Nahant and Swampscott, Saugus sends its sewage to the Lynn Regional Wastewater Treatment Plant, where every gallon treated with chlorine and other chemicals costs the town. By eliminating rain and groundwater from the mix, the town’s sewage treatment costs are expected to plummet dramatically.Saugus has been under a consent order from the state Department of Environmental Protection to get the job done.”The DEP is using this as a model for other communities,” said Ross, noting that Saugus has also eliminated more than 100 sump pumps in homes throughout the town that were adding to the problem.”Cleaning out the pipes has helped to increase the flow,” he said.Town Manager Andrew Bisignani said the $1.7 million project is expected to come in at $1.5 million, a $200,000 savings. It has not been determined whether those funds will be used to pave side streets off Hamilton Street, or to upgrade Hamilton Street itself.