Did you know that there is a wetland in Phoenix?

On Wednesday members of the Arcosanti planning, public relations, landscaping, habitat, utilities, and construction departments were treated to a two hour long guided tour by Dennis Porter, the assistant director of waste management for the city.

The Tres Rios project comprises twelve hundred lush, riperian acres in southwest Phoenix which eventually feed back into the Salt River. Water for the wetlands is provided by the 91st Street Waste Management Facility. Here it passes through one of five separate facilities for reclamation before being discharged into the wetlands at the astounding rate of 100,000-300,000 cubic meters per day.

Dennis oversees both the 91st Street Waste Management Facility and the Tres Rios Project. On an average day the facility takes in around a million gallons, the waste for a little over half of the city of Phoenix. The process starts with separating the solids from the liquids through a system of gravity tanks and centrifuges. Solid waste is put into digesters where it sits for up to eighteen days before being dried and sold as fertilizer to non-food agriculture farms. Liquid effluent is treated in a series of pools and then sent through a pipe to Tres Rios.

The construction of Tres Rios was accomplished through the collaborative efforts of the city of Phoenix and the Army Corps of Engineers. The goal of the project was to reduce flooding in nearby agricultural areas by controlling water runoff and to help reintroduce a portion of verdant green habitat which had been severely damaged through overuse of water in the area.

Work offically started in 2010 with the transformation of arid farmland into a series of “cells” which could be flooded to an ideal depth to capture the discharge. Plants including rushes, arrowhead, cattail, and floating aquatics were then introduced to create the habitat. Once effluent from the nearby facility enters the system, additional filtration is provided by the passage of the water through the wetland until it eventually reaches an outflow point. The water from that outflow has helped restore an additional 700 acres of of habitat to a previously dry portion of the Salt River. The area is popular amongst fishermen, bird watchers, hikers, and even the occasional hunter. 

Arcosanti’s interest in the Tres Rios project stems from our desire to see an upgrade to our own waste treatment system, currently handled by a small oxidation pond. Upgrading or replacing that system would all us to house more residents and overnight guests on our site and begin the process of acquiring major construction permits for future projects.

(photos and text by Tim Bell)

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