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Blue Clauses

By Buck Abbey, ASLA, Robert Reich School of Landscape Architecture, Louisiana State University






Figure 1
Careful water management requires using minimum water volumes and maintaining proper soil moisture. Devises such as ground moisture sensors take the guesswork out.
Photo: Soil sensor equipment courtesy Toro Irrigation Co.


"Drip irrigation is typically used to maintain moisture, whereas sprinkler and gravity irrigation may be used to replace depleted moisture." -- Toro Micro-Irrigation Owner's Manual, 2012


Irrigation Design
Green laws contain blue clauses that affect irrigation design, water conservation or water harvesting. In reviewing landscape codes from across the nation, I was surprised to find the 'blue clauses' that apply to irrigation are not very well developed compared to the design, planting, construction and materials clauses found in most technical codes used by landscape architects. Present standards are best represented by the following:

Albuquerque: Code of Ordinances Chapter 6, Water ? 6-1-1-10 Irrigation System Standards, and Ord. 18-1995, Appendix D Water Conservation Landscaping and Waste Water Ordinance sets standards for water use, irrigation design and limits on water waste, especially fugitive water. The intent of the ordinance is to reduce overall water use per capita by 30 percent, and to reduce yard irrigation and irrigation-related water waste, which comprise over 40 percent of the city's total annual water usage; to reduce peak summer usage, which is two to three times winter usage; to reduce irrigation without sacrificing landscape quality by using lower water use plants, improved design and planting practices, different watering practices, and better irrigation system design and maintenance.

 




Figure 2
California's AB 1881 provides guidelines for standards for use of green irrigation equipment. This design of hydrozones by Lindsey Folse is based on plant water needs, as well as the preparation of irrigation plans and landscape documentation packages.



Hudson County New Jersey:
Land Development Regulations, Sec. VII, Design Standards, Art 15. g. xii. October 23, 2008 states: "On site irrigation methods shall be specified. Water hose locations shall be convenient and underground irrigation shall be provided if deemed appropriate and suitable."

New Orleans: Comprehensive Zoning Ordinance (CZO), Article 23. Landscape, Stormwater Management & Screening, Sec. 23.4, C.1.b & c require that half of small landscape area must be designed with drought tolerant plants; that all planting areas over 2,500 sq. ft. must show on the landscape plan water use calculations not exceeding the maximum applied water allowance of 25 gallons per sq. ft. Palm Beach County: Unified Development Code, Supplement no. 10, Article 7 Landscaping, Chapter E. Sec. 7 Irrigation, June 2011 and Landscape Technical Manual Title 4 Landscape11.30.2011. Landscape plans must incorporate Xeriscape industry standards that use efficient irrigation, mulching, soil improvements, native plants and using alternatives to high water use turf grass. The Florida Friendly Landscaping principle may also be used to meet this requirement.

SITES also places emphasis on effective irrigation design. To meet the SITES credit to reduce outdoor water use it is necessary to reduces potable water use by 75 percent, a baseline average water consumption volume calculated by the EPA WaterSense Water Budget Tool at www.epa.gov/watersense/water_budget/application.html.

Blue clauses and SITES see the use of potable water supplies as a resource that must be carefully managed.

 




Figure 3
California requires that irrigation plans be in conformance to specific evapotranspiration rates, water and budget calculations. This irrigation plan was designed by Lauren Patti.



Water Management
Careful water management requires using minimum water volumes and maintaining proper soil moisture using devises such as "ground moisture sensors as seen in Fig. 1. Water harvesting from parking lot surfaces, rooftops, grey water systems, constructed wetlands or from site detention ponds is the preferred way to reduce the use of potable water. Another way is to send water directly to the plant with sophisticated drip irrigation systems that use ground moisture sensors.

And of course a third best management strategy is to ensure that a large percentage of the landscape is completely dependent upon the use of native plants that survive with local monthly rainfall amounts.

 




The intent of Albuquerque's water ordinance is to reduce overall water use per capita by 30 percent, and to reduce yard irrigation and irrigation-related water waste, which comprise over 40 percent of the city's total annual water usage.



Irrigation Regulations
Central to that management is having local landscape regulations that guide the grower, designer and irrigation contractor in the proper use of irrigation system components as manufactured by leading irrigation companies such as Toro, Rainbird, Hunter and others.

Well-written regulations provide guidelines that insure the landscape industry sees potable water supplies as a limited resource not to be wasted by inefficient design and poor installation practices.

EPA intervention and dwindling water supplies in the West are leading to new best practices in the design of irrigation systems. These new practices are finding their way into regulatory form. Take for instance the statewide irrigation code for California, AB 1881. It amends Chapter 559, California Civil Code that resulted in Title 23. Waters, Division 2, Chapter 2.7. Model Water Efficient Landscape Ordinance (MWELO). The 33-page ordinance whose purpose is to "establish a structure for planning, designing, installing, maintaining and managing water efficient landscapes in new construction and rehabilitated projects," has been adopted in every community statewide. This state law provides guidelines for standards for use of green irrigation equipment, design by hydrozones (Fig. 2, designed by Lindsey Folse), based upon plant water needs, as well as the preparation of irrigation plans and landscape documentation packages.

Irrigation plans (Fig. 3, designed by Lauren Patti) must be in conformance to specific evapotranspiration rates, water and budget calculations. California provides a water budget calculator to assist the landscape architect in the completion of a water efficient landscape worksheet www.water.ca.gov/wateruseefficiency/landscapeordinance. Results are computed as estimated total water use (ETWU) in gallons, cubic feet and acre-feet per year. This is all that can be used each year. This calculation is adjusted for landscapes of various regions. Landscapes less than 2,500 square feet are exempt.

A sustainable irrigation design provides many environmental services. The primary purpose of green irrigation is to reduce the use and waste of potable water; secondly, replace it with available recycled storm water and other harvested grey water using state of the art environment sensing irrigation equipment.

Editor's note: You can contact LASN's associate editor Prof. Buck Abbey via email at lsugreenlaws@aol.com, or by calling the Robert Reich School of Landscape Architecture at 225.578.1434.







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