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Stormwater Capture and Reuse Systems Help Achieve Stormwater Management Goals

San Diego, CA, USA
San Diego Regional Airport Authority

Government Champion

San Diego County Regional Airport Authority

Cost

Initial:
50 Million USD

Project Status

In Progress/Under Construction since 2022

Challenges Addressed

Motivation

Funding / Financing

Project Type

At a Glance

The San Diego County Regional Airport Authority is making strides in achieving our stormwater management goals through a stormwater capture and reuse system. The system helps meet stormwater discharge regulatory requirements, reduce potable water consumption, and ensure resilience.

Problem Addressed

In 2016, California slid into a 5-year drought. Only 17% of the San Diego region’s water supply came from local sources, and 80% of water consumption at San Diego International Airport (SAN) was used for non-potable purposes. For these reasons, the San Diego County Regional Airport Authority (Airport Authority) began developing a Water Stewardship Plan that explored ways to reduce potable water consumption, protect the natural environment, and innovate.

Relying on potable water can strain local water resources and increase demand for imported water. However, water is an essential utility needed for the Airport to run. Potable water is typically used for functions that could use non-potable water like HVAC systems, vehicle washing, and toilet flushing.

Additionally, SAN occupies bay-front property and stormwater produced on the Airport’s mostly impervious surfaces travels through the storm drain system directly to the San Diego Bay. This standard system allows for the travel of pollutants into the natural environment and fails to take advantage of capturing a valuable resource. Facing an uncertain, but likely more stringent, regulatory environment, the Airport Authority intends to control discharges more effectively and to eliminate unnecessary discharges—going above and beyond what is required by the regulations.

In need of a guide for implementing sustainability into future projects, the Airport Authority works with the Institute for Sustainable Infrastructure to apply their Envision Rating system to our Airside Improvements Project that support the development of the New Terminal 1. The proposed elements discussed below will produce sustainability benefits including preserving sites of high ecological value, maximizing resilience, reducing operational water consumption, protecting surface and groundwater quality, and reducing construction water consumption.

San Diego County Regional Airport Authority used/is using an innovative stormwater capture and reuse system to address this/these challenge(s).

Solution(s) Used

To model the performance of the Stormwater Capture and Reuse System in meeting stormwater pollutant control regulations, the Airport Authority used the USEPA's Storm Water Management Model (SWMM). The model evaluated 563 inches of rainfall that fell on the Airport during a 57-year historical period which led to the design of a capture and reuse system with more than 9 million gallons of storage capacity—enough storage to capture approximately 39 million gallons of stormwater annually from roughly 200 acres of Airport property.

Before proceeding with the implementation of such a system, the Airport Authority shared the concept with and sought input from other San Diego region stormwater co-permittees, NGOs, and staff from the local regulatory agency, namely, the San Diego Regional Water Quality Control Board. Most considered the concept of creating more than 9 million gallons of storage capacity to be ambitious. However, onsite retention would allow the Airport Authority to meet the Airport stormwater discharge goals in the San Diego Bay Watershed Water Quality Improvement Plan (required by the San Diego Region Municipal Stormwater (MS4) Permit), to meet any future Total Maximum Daily Loads (TMDLs) for San Diego Bay, and to provide a new source of non-potable water.

As a result of the research, at SAN there are now four existing elements of the stormwater capture and reuse system, and four proposed elements.

Existing elements include:

1. Terminal 2 Parking Plaza Storage – Storage for stormwater captured from the upper deck with a capacity of nearly 100,000 gallons.

2. North Side Cistern – A three-million-gallon underground storage tank on the north side of the Airport.

3. North Side Storage and Infiltration – Underground storage and infiltration chambers with 0.64 million gallons of capacity, and bioswales to channel stormwater infiltration.

4. Airline Support Building Storage and Infiltration – Two infiltration beds with a total surface area of approximately 2.65 acres.

The four Proposed elements that are a part of the New T1 include:

1. South Side Cistern – An approximately 1.5-million-gallon underground tank (cistern) on the south side of the Airport.

2. Airfield Storage and Infiltration – Several infiltration areas located on the airfield.

3. Terminal 1 Parking Plaza Storage – Underground storage tanks or pipelines at the proposed new Terminal 1 Parking Plaza.

4. Roadway Storage and Infiltration – Underground infiltration and storage area below the proposed new Terminal 1 roadway.

Instead of discharging into San Diego Bay through our storm drains, much of the stormwater at SAN is treated to remove contamination. Additionally, infiltration systems use soil chemistry and biology to filter and treat contaminants as it infiltrates into the ground. Collected and treated water is used as cooling tower makeup water at the Airport Central Utility Plant and may be used to flush toilets, wash vehicles, and mitigate construction dust.

Outcomes

  1. SAN seeks to create several million gallons of stormwater storage capacity.
  2. Four stormwater capture and reuse system elements currently exist at SAN and another four are proposed in the New T1.
  3. Collecting and reusing stormwater reduces the amount of stormwater that enters the San Diego Bay through the Airport’s outfalls. This helps prevent polluted stormwater discharges.
  4. Collecting and reusing stormwater provides an alternative water source for onsite non-potable uses and therefore reduces the strain on local water resources.

Lessons Learned

  1. Exceeding regulatory requirements will enhance performance and may reduce or altogether avoid future costs associated with regulatory compliance.
  2. Considering the likelihood and degree of potential regulatory changes, a stormwater capture and reuse strategy may ultimately save SAN money on costly retrofits.
  3. Stormwater capture and reuse funding can be rolled into larger capital improvement projects. The price listed here is approximate and includes existing elements of our program.

Something Unique

With proper approvals from the San Diego Regional Water Quality Control Board, the Stormwater Capture and Reuse System would allow 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. Approval of the program enables the Airport Authority to “bank credits” from the elements of the System that can be applied towards future airport developments.

Who Should Consider?

Any campus facilities or community developments with hardscape interested in meeting or exceeding stormwater compliance requirements.

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