Optimizing an Asset through Cleaning and Inspection: The Miramar Trunk Sewer

The Puerto Rico Aqueduct and Sewer Authority (PRASA) has approximately 20,000 lineal feet of trunk sewer system that conveys combined wastewater and storm water flows from the western portion of San Juan to the Puerto Nuevo WWTP. The trunk sewer ranges in diameter from 36" to 84" in diameter, is primarily constructed with reinforced concrete pipe (RCP), and the age ranges from 40 to 45 years old. The system also has three siphons that convey flows under channels that discharge into the ocean. The system comprises of three sections of trunk sewer: 1) San Juan Trunk Sewer 2) Baldorioty Trunk Sewer 3) Miramar Trunk Sewer (Upper and Lower sections) Much of the system has been in service in excess of 50 years, is corroding, and filling with sediment. Throughout the life of the trunk system, major cleaning has not been performed. Part of the system, the Old San Juan sewer, was constructed of brick conduits collecting both sewer and storm waster. Six shallow sea discharge pipes were diverted in the 1970's to a collection system which pumps all wastewater and storm water to the gravity trunk main, which is the object of our study. During wet weather events, when all lift stations are operating at their maximum capacity, it was common for the trunk system to back up and cause manhole lids to float and be carried down streets. An overall map of the system is presented in Figure 1.