A drywell is a shaft that lets a retention basin drain down into the ground instead of sitting full. Goodyear's stormwater manual has specific rules for building one.
Goodyear's drywell standards
- Depth: the excavation has to penetrate 10 continuous feet of permeable material, or reach 75 feet, unless otherwise approved.
- Design rate: 0.25 cubic feet per second per drywell, unless the manufacturer recommends less.
- Grates: 0.5 feet above the basin bottom. Covers in landscaped areas sit 0.2 feet above finished ground.
- Location: not in city right-of-way.
- Purpose: retained stormwater has to drain within 36 hours. Basins without a positive disposal method, such as a drywell, are limited to 1 foot deep and 1,000 cubic yards.
What to ask
- Who designed the drywell, and was a percolation test done?
- How deep is the permeable layer at this site?
- Who installs the drywell, and who handles the basin grading around it?
- What maintenance will it need to keep draining in time?
The Arizona Registrar of Contractors licenses excavating and grading as R-2, A-5 or CR-2. Ask whoever installs the drywell which license they hold for that work.
Sources
- City of Goodyear: Engineering Design Standards and Policies Manual, Chapter 3, Stormwater Management (2017)
- Arizona Registrar of Contractors: License Classifications
Reviewed October 20, 2026. Rules, prices and contacts change, so check the source before relying on it.
Questions and answers
How deep does a drywell have to go in Goodyear?
Goodyear's manual says the excavation must penetrate 10 continuous feet of permeable material, or reach 75 feet, unless otherwise approved.
Can a drywell go in the street right-of-way in Goodyear?
No. The manual says drywells may not be installed in city right-of-way.
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