Background

CESPT is responsible for providing water and wastewater services in both Tijuana and Playas de Rosarito. In 2012 water coverage in Tijuana was estimated at 99% and wastewater collection at 90%. Wastewater treatment is provided through four activated sludge treatment plants: the San Antonio de los Buenos Wastewater Treatment plant (WWTP) with a 25 million gallon a day (mgd) capacity; the International WWTP in San Ysidro, CA (25 mgd); the Arturo Herrera WWTP (11 mgd); and the La Morita WWTP (5.8 mgd).

As part of its master plan to extend wastewater collection and treatment services to 100% of the city’s population and achieve zero discharges of untreated sewage into rivers and streams, CESPT is extending wastewater services to the La Cuesta subdivision, on the southeast side of Tijuana. Residents currently rely on latrines, septic tanks, or discharges to open drains for their wastewater disposal, posing environmental and health risks. An estimated 309 households in this subdivision are generating approximately 2.50 lps or 57,067 gallons per day (gd) of wastewater that is not being disposed of properly.

In addition, CESPT also intends to improve its wastewater conveyance system by rehabilitating the Farrallon collector and the SEDUE-SAAS force main, both of which have deteriorated with age and suffered several line breaks. Untreated wastewater runoff from breaks in the Farallon collector located on the west side of Tijuana has resulted in beach contamination along the Pacific coast. Breaks in the SEDUE-SAAS force main, also known as the “Old Parallel Line,” have impeded the conveyance and potential reuse of treated wastewater flows from the Tijuana River, which are currently being pumped back into a collector and re-contaminated with raw sewage. This force main will also serve as a backup line for the “Parallel Line” which conveys approximately 1,100 lps of wastewater flows to the San Antonio de los Buenos WWTP.

Description

CESPT proposes extending and improving its wastewater collection system through three projects.

• Construction of the La Cuesta sewer system, which includes the installation of approximately 2,689 meters (8,822 ft) of sewer lines and 309 residential hookups. Wastewater collected in the project area will be treated at the San Antonio de los Buenos plant and discharged into the Pacific Ocean.
• Rehabilitation of the Farallon collector, which entails replacing approximately 2,927 m (9,603 ft) of pipeline.
• Rehabilitation of the SEDUE-SAAS force main, which entails replacing approximately 330 m (1,083 ft) of pipeline.

Benefits

This project will reduce environmental and health hazards associated with inadequate sewage disposal, thus providing a cleaner healthier environment for local residents, as well as for people along the Pacific coast. Specifically, the La Cuesta sewer system will provide first-time service to 309 households, and is expected to collect an estimated 57,067 gd of wastewater for treatment. Rehabilitation of the conveyance system will reduce the risk of line breaks and leaks, preventing approximately 235 lps (5.3 mgd) of untreated sewage discharges.