Background

In 2013, water service and wastewater collection coverage was estimated at 99.4% and 97.8%, respectively. All collected wastewater is conveyed to the city’s wastewater treatment plant, which is operated by the company AREMA under a 20-year concession agreement. The treatment plant has an installed capacity of 520 liters per second (lps) or 11.9 million gallons a day (mgd).

In June 2013, Piedras Negras experienced uncharacteristically heavy rains that caused flooding throughout the city and significantly damaged the existing wastewater collection infrastructure. Two sections of the Rio Bravo Collector collapsed, interrupting wastewater conveyance to the treatment plant and causing approximately 2.3 mgd of raw sewage to be
discharged into the Rio Grande. Manhole frames and covers located throughout the city also suffered substantial damage due to the floods, which has resulted in additional deterioration of the wastewater collection system.

Description

The project to repair the wastewater system includes the following
components:

• Replacement of two sections of the Rio Bravo Collector: the
  Campo Venados and Escalante.
•  Replacement of the gravity main sewer collector at Arroyo El
  Soldado to repair the connection at the Santa Maria subdivision.
• Repairs in Lift Station No. 4, including desilting of the wet well,
  the replacement of the perimeter fence and rehabilitation of the
  access road to the lift station.
• Repairs to 154 manhole frames and covers located throughout the
  city.

Benefits

The project will ensure the proper operation of the wastewater collection infrastructure in Piedras Negras and will reduce environmental and health hazards associated with untreated wastewater discharges, thus providing a cleaner healthier environment for local residents, as well as for communities downstream. Specifically, the project will prevent up to 2.3 mgd of untreated wastewater discharges.