The purpose of the Wastewater Reclamation Facility Feasibility Study is to analyze various options available to meet the City of Chula Vista's long-term sewer treatment capacity needs. As a part of the study, our consultant, RMC Water and Environment (RMC), is required to evaluate the option of constructing a wastewater treatment facility in Chula Vista in comparison to the option of purchasing additional treatment capacity rights in the Metropolitan Wastewater Department (Metro) of the City of San Diego.

Statistics on the Project

• Chula Vista currently has 20.86 million gallons per day (mgd) of allocated wastewater treatment capacity rights in the Metro system.
• Currently, Chula Vista generates about 16 mgd.
• Based on current trends, the City could reach 22 mgd in the next decade.
• Per the 2005 Wastewater Master Plan, the City could reach 26.2 mgd by build-out.

To meet this capacity shortage, the City has two options to increase its treatment capacity:

1. Purchase additional treatment capacity rights from the Metro system; or
2. Construct a new 6 mgd independent wastewater treatment plant (WWTP) in Chula Vista; the WWTP would provide the community with a new source of recycled water for non-potable use.

To address the various constraints within the City, RMC is exploring various types of wastewater treatment plants that are condensed, neighborhood friendly, and innovative. This outreach meeting presents eight potential locations within the City of Chula Vista to site a new WWTP and provides information on each site as well as a comparison of the sites.

Potential Sites

The City identified eight potential sites within the City of Chula Vista as possible locations to site a new water reclamation facility. Black arrows show the general direction of wastewater flow. Existing sewer and recycled water lines are also shown for use in site comparison. All wastewater from the City currently flows to the Point Loma Treatment Plant.

Project Implementation Requires Many Years

Wastewater Treatment 101 - The Basics are really quite simple

Engineering Site Evaluation - Summary Findings and Conclusions

The following provides a description of our evaluation and findings for each criterion.

Size

Each site was evaluated on whether it was the adequate side to site a recycled water treatment plant, advanced treatment facilities required for live stream discharge, and also whether it had sufficient space for a community park. For the smaller sites it was noted if conventional treatment such as Sequencing Batch Reactor (SBR) compared to a member bioreactor (MBR) was feasible.

• Site 6 is not of sufficient side and has a high pipeline cost.
• Site 1 is relatively small and will require a very long recycled waster pipeline to connect to OWD pipeline.
• Site 5 is relatively small and does not allow much treatment flexibility.

Wastewater Availability

This evaluation considers how to get adequate wastewater to the site to achieve the wastewater capacity goals of the project. Wastewater availability was determined for each site based on our build-out conditions.

The sites east of I-805 will not have adequate wastewater flow from a single sewer and will require diversions from both the Poggi Canyon Trunk Sewer and the Salt Creek Interceptor to get to 6 MGD.

Pumping

This evaluation considers relative site differences in pumping. In all cases we will need to pump wastewater through the treatment plant and then pump recycled water to the Otay Water District (OWD) system. However many of the sites will need to have separate sites for the wastewater diversion pump stations because we cannot flow by gravity from the sewer to the treatment plant.

• All the sites will have similar total pumping head because we are taking wastewater from the sewer at relatively low elevation and pumping recycled water up to elevation 450 ft.
• The sites north of Main Street will require separate sites for the diversion pump station: the sites south of Main Street can flow by gravity to the treatment site where the diversion pump station can be located.

Piping

This evaluation considers the total length of pipe of both the sewer diversion pipe of both the sewer diversion pipe to the treatment plant and the recycled water pipe from the treatment plant to OWD.

• The sites west of I-805 will have a short sewer diversion pipeline but a long recycled water pipeline.
• Site 6 has extremely large total pipeline distances and thus a very high cost.
• Site 1 has a very long total pipeline distance and thus a higher cost than other sites south of Main Street.