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3 Million Gallon Cistern Collects Stormwater for Reuse at San Diego International Airport

San Diego, CA, USA
San Diego Regional Airport Authority

Government Champion

San Diego County Regional Airport Authority

Cost

Initial:
24 Million USD

Project Status

Operational since 2022

Challenges Addressed

Motivation

Funding / Financing

Project Type

At a Glance

The Northside Stormwater Capture Cistern is designed to collect stormwater runoff from 80 acres of Airport property and to capture and reuse approximately 16 million gallons annually. At final completion, the Airport Authority intends to reuse the water to wash vehicles at its Rental Car Center.

Problem Addressed

The Airport is located in a drought-prone arid region that relies on mostly imported water. In the past, the Airport used potable drinking water for all its operations. However, 80% of the water is used for non-potable sources. While some regional recycled water programs exist, there are currently no recycled water sources in the vicinity of the Airport that can be utilized.

In 2016, at the same time a drought was straining regional water resources, the Municipal Stormwater (MS4) Permit began to require assessment of water quality impacts through a hierarchy of treatment controls for stormwater discharges from new developments. According to the permit, new projects are to keep stormwater on site—by either infiltrating it or capturing and reusing it.

Facing ever more stringent stormwater regulations and the desire to reduce potable water use, the Airport Authority looked for innovative solutions to capture water resources available, and to effectively use them.

The San Diego County Regional Airport Authority used/is using a large underground stormwater capture tank to address this/these challenge(s).

Solution(s) Used

The Northside Stormwater Capture Cistern is a 3-million-gallon cistern on the north side of the Airport and is one of the first constructed elements of the Airport Authority’s Stormwater Capture and Reuse Program. The cistern was constructed to capture stormwater runoff from 80 acres of Airport property and is designed to capture and reuse approximately 16 million gallons annually. The captured stormwater will be used to wash cars at the nearby Rental Car Center, where an average of 4,000 cars are washed daily. Currently, the Rental Car Center is using approximately 10 million gallons of potable water annually.

Construction of the northside cistern began in December 2018 and the project was substantially completed in September 2020. The floor of the concrete tank is nearly five feet thick with almost 3-foot-thick walls. There are 32, 24-inch round diameter columns, approximately 26 feet tall that help support the structure. The cistern’s inside diameter is over 158 feet and is 35 feet deep.

With proper approvals from the San Diego Regional Water Quality Control Board (Regional Board), the Stormwater Capture and Reuse System allows the Airport Authority the unique opportunity to use the “alternative compliance” mechanism in the MS4 Permit to meet post-construction BMP requirements for development/redevelopment. The program enables the Airport Authority to “bank credits” (on what is essentially an “acre-for-acre” basis) from the cistern that can be applied towards future airport developments, like the replacement of Terminal 1. The Airport Authority Alternative Compliance Program is the first such program to be approved in the region.

The Northside Stormwater Capture Cistern is one of the first element of the Stormwater Capture and Reuse System to spring from the Airport Authority Water Stewardship Plan (WSP). It exemplifies goals within the WSP to develop new sources of water that can offset uses that unnecessarily rely on potable water. The Airport Authority is committed to offsetting the use of potable water for non-potable purposes in airport design, operations, and maintenance by continuing the pursuit of innovative ways to perform water capture and reuse.

Outcomes

  1. Motivated by the desire to be good environmental stewards, the Airport Authority uses stormwater capture and reuse infrastructure to use less drinking water for non-potable functions.
  2. A 158-foot wide, 35-foot deep, 3-million-gallon cistern has been constructed to capture and reuse stormwater from the northside of the Airport.
  3. Once connected to the appropriate systems, captured stormwater will be treated and reused for non-potable uses like washing vehicles in the Rental Car Center.

Lessons Learned

  1. This type of project can take years to complete. Recurring check-ins with engineers and design teams are recommended to remind them of the organization’s goals help facilitate progress.
  2. Sustainability planning is a way to future-proof yourself from regulations.
  3. There is currently no authority having jurisdiction (AHJ) providing a permit to use captured stormwater, but the state is moving in the direction of allowing these types of uses.

Something Unique

Development of the Northside Cistern is driven by scientific analysis and provides an innovative response to MS4 Permit requirements for both stormwater pollution prevention and post-construction BMP requirements for development/redevelopment, while creating a new source of water in San Diego’s drought-prone arid environment. This project was funded as part of a larger capital improvement project. Price listed is approximate.

Who Should Consider?

Anyone in a water stressed environment interested in capturing and reusing stormwater in coordination with new development.

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