Location: Wilmette, Illinois
Application: Rainwater Harvesting
Product used: DoubleTrap 10’-0’’
Number of pieces: 16
Number of systems: 1
Total Water stored: 5,200 cf
Project Description: A rainwater harvesting system was installed underneath Baha’i Temple’s garden located at Wilmette, IL. A StormTrap system is utilized to capture the rainwater and the detained water is used to irrigate the nine gardens that surround the Temple. Bill Perry, P.E., vice president of Watermark Engineering Resources Ltd, explains that prior to the installation of the system, the gardens were irrigated with the village water. “In keeping with their desire to be an environmentally friendly neighbor, the Baha’i team decided to install infrastructure that could capture the natural stormwater on the site and reuse it for irrigation purposes” explained Perry.
Challenges: There were two main challenges for this project. The first challenge was the need to capture as much rainwater as possible minimizing the disturbance of existing infrastructures. The second challenge was the short time frame to install the system.
Perry explains the concerns about disturbing the existing infrastructure “we didn’t want to tear up all the gardens,” “There’s an area just north of the cistern that’s approximately 10 feet lower than the rest of the gardens, which is used as access to the lower level of the House of Worship. There was a concern that we wouldn’t be able to pick up about half the runoff from the grounds because we wouldn’t be able to take the pipe through this area. Ultimately, we were able to bring the water around underneath the entryway to the cistern, which provided an additional source of volume in the cistern.”
The second challenge was the time frame to have the project ready. “They wanted the grounds completed for a ceremony to recognize the 100th anniversary of the groundbreaking, in the spring of 2012” said Perry. “The gardens had to be constructed, and they’re very intricate.
Because the cistern is underneath a garden, we had to get the unit in, backfill, and then allow enough time for things to start growing again” Perry.
The contractor Biaggi Plumbing installed the system in one day and the project was completed months before the due date. “The installation went very well, very quickly after the hole was dug,” stated Perry.
Solutions: A 16 unit 10’-0’’ DoubleTrap was placed underneath the garden holding 5,200 cf of rainwater. The system was wrapped in a HDPE linear membrane to make it impermeable and the membrane was surrounded with geofabric. A valve on the basin controls the flow of water to a separate structure that filters any remaining particles that haven’t settled out. The filtered water flows to a pump in the temple, which distributes the water to all nine gardens. In the winter months, the valve can be opened so stormwater flows directly to the Metropolitan Water Reclamation District (MWRD) channel, which empties into Lake Michigan.
The basin provides enough water for three to four nights of irrigation when it is full. Overflow goes directly to the MWRD channel, and if there isn’t enough water, the system includes a bypass so township water can be used.
Perry mentions that the team is proud to be part of this rewarding project. “The members of the Baha’i faith have done things that are good for the earth” affirms Perry.