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iSWM Tools - Case Studies



Local Projects using iSWM Principles

Corgan Associates Headquarters
401 North Houston Street, Dallas, TX

Project Description

The Corgan Associates Building is a new building in Dallas’ Historic West End District and was completed in February of 2007. The building is Silver LEED Certified and one of the features that helped achieve that certification is a rain harvesting cistern. The cistern collects rainfall runoff from part of the roof and stores it for use in irrigating the landscaping on the property. The rain harvesting system reduces the stormwater runoff volume from the site and helps lower water costs for the owner.

Key iSWM Features

The rain harvesting cistern is 10 feet in diameter and 10 feet tall. It is made from concrete and includes a manhole on the top that is used for maintenance. Two 6-inch pipes direct the roof drainage into the top of the cistern. Pipes at the bottom of the cistern connect to the irrigation system for the site’s landscaping. A concrete flume at the bottom of the cistern directs any overflow from the cistern towards the west side of the property.

Drawings and Technical Information

The area of site is approximately 36,000 ft² with 22,000 ft² of roof area and 3,000 ft² of landscaping.  Of the 22,000 ft² of roof area, approximately 13,000 ft² is directed towards the rain harvesting cistern.  The cistern has approximately 5,800 gallons of storage, which would store a 0.72 inch rainfall event.  To store the 1.5 inch storm event would require an additional 6,355 gallons of storage.  Approximately 3,900 gallons of water for irrigation is required in an average month to maintain the landscaped area of 3,000 ft².

No drawings for the project are available.

Project Resources

Project Representatives

Brenda Patterson
Building Manager
Corgan Associates, Inc.

Alan Richards
Corgan Associates, Inc.


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