In January 2010, AB 1881 went into effect in California, new sections were added to increase the efficient use of water in the landscape. It seems that most landscape architects and agencies are familiar with the new guidelines, but others in the industry have not acknowledged its mandates.
The original ordinance, AB 325, was written and created in the middle of a 6-year drought. AB 325 was intended to make sure landscapes were watered efficiently however the tools were not in place to guarantee enforcement.
Grading design plans are now required by the project engineer to provide for the efficient use of water. The ordinance requires that the site’s grading be designed to minimize soil erosion, contain run-off and prevent water from being wasted. In addition to labeling site elevations and showing drainage patterns, storm water retention improvements are also highly recommended.
All irrigation run-off (even though irrigation run-off is prohibited in other sections of the ordinance) and normal rainfall are required to remain on site, and is not allowed to drain onto non-permeable surfaces. Also, the landscape areas of the site are to be designed to avoid compaction. Wouldn’t that be nice if our landscape areas were not compacted to 95% compaction? How many grading plans have you seen in the past 21 months with the statement, “I have complied with the criteria of the ordinance and applied them accordingly for efficient use of water in the grading design plan?”
Site storm water management requires that run-off is minimized and infiltration is encouraged. Rain gardens, cisterns are also strongly encouraged. Several companies have developed self-contained storage tanks (with pumps) to aide in the distribution of storm water. How many of the sites that you are involved with contain the run-off water? As a ballpark figure it costs about $2.00 to $3.00 to store a gallon of water in an underground tank. Then the water must be pumped to be used in most irrigation systems, unless a gravity system can be designed into the site.
Most agencies encourage the use of rain and other run-off; however they require the water to be distributed in the landscape in a subterranean irrigation system (i.e. Los Angeles County Department of Health ). The concern is that the water quality cannot be verified so the agencies do not want the water distributed in a spray irrigation system that might atomize unknown chemicals into the air.