Ponce de Leon Combined Sewer System Separation Planning, Design, and Construction

Abstract

In a highly developed corridor along Ponce de Leon Avenue in San Juan, Puerto Rico, the Puerto Rico Aqueduct and Sewer Authority (PRASA) have a combined storm water and sanitary sewer collection system that conveys flows into their Puerto Nuevo Wastewater Treatment Plant. To reduce flows and treatment costs, a plan was developed and implemented to separate the storm water and sanitary sewer flows that will minimize disruption to the businesses along the corridor. The existing combined flow channel is approximately 10,700 feet long, located in the center of Ponce de Leon Avenue, which runs through a mainly business and commercial area within a heavily congested arterial. There are three one-way traffic lanes and a dedicated one-way bus lane. Many of these banks, governmental and private office buildings, will experience disruption during construction activities, so the new sanitary sewer lines had to be carefully planned to minimize impacts to traffic and to the local businesses. To minimize disruption where possible, the design team elected to construct two sanitary sewer collector pipelines, one on each side of the road so that service laterals would not need to extend across multiple traffic lanes. The following steps were followed to complete the planning, design and construction phasing of the project: (1.) Topographic mapping and surveying. (2.) Subsurface Utility Engineering. (3.) CCTV of the existing combined system channel to locate the existing sewer and storm water laterals. (4.) Alignment study for the new collector sewers. (5.) Identification of sections of sections of the collector lines to be constructed by other than open cut methods. (6.) Preliminary Engineering Report summarizing project design, construction sequencing, schedules and cost estimates. (7.) Geotechnical Report (8.) Final design (9.) Bidding (10.) Construction The paper will discuss all aspects about the project and describe the challenges and insights gained.