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FEATURE ARTICLE, OCTOBER 2005
WATER WORKS
Good irrigation design helps developments grow without draining resources.
Charles Stassi
Early involvement of a landscape architect and irrigation designer can have a significant payback in site development. A landscape plan coupled with a good irrigation design can save time and money during site development and maintenance, as well as increase the property's value because of its aesthetic appeal. Irrigation is an important consideration at the onset of any project. If a site's irrigation is not properly designed, landscape maintenance becomes a costly and burdensome task and the property's value can actually decrease. Good irrigation that achieves maximum results involves several important considerations by an experienced irrigation designer.
• Selecting from a variety of available irrigation equipment and determining its best use. It's important to know when and where to use each type of sprinkler head, valve, controller, irrigation pipe, high volume and low volume appliances, moisture sensors and more.
• Suitable landscaping that allows for efficient irrigation and lawn maintenance.
• Knowledge of how much water, where and for how long based on site conditions.
• Importance of a good maintenance plan for a successful watering operation.
• Knowledge of what plants work well together based on site conditions, soil types, and watering requirements.
• Identification of water sources and understanding how much pressure and volume each provides.
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A landscape plan coupled with a good irrigation design can save time and money during site development and maintenance, as well as increase the property's value because of its aesthetic appeal.
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In addition to cost savings and aesthetics, another significant benefit of a good irrigation design is the conservation of water — a precious resource —notably during drought periods such as those experienced in recent years. The U.S. Green Building Council has specified water conservation as one component of LEED® (Leadership in Energy and Environmental Design) – a comprehensive program that awards credits and provides accreditation for projects that practice sustainable or “green” construction. Projects that follow the guidelines setup by the U.S. Green Building Council for new or renovation construction can achieve various levels of accreditation and are registered as “green buildings.” The accreditation means that the project was designed and built to a set of standards that will help protect the environment for today and into the future. The council uses the total credits, comprised of a series of points for meeting certain guidelines, to award projects a certified, silver, gold or platinum accreditation.
Under the LEED program, two credits related to water efficiency and irrigation are available. Developing a landscape irrigation system that conforms to LEED guidelines is not necessarily a difficult task for an experienced landscape architect. However, if the landscape architect does not have the technical background and extensive knowledge in irrigation design and construction, the system will fall short of its goal of sustaining the plant material it is designed to support and become a maintenance burden for the end user.
Credit 1.1
Water Efficient Landscaping: Reduce By 50%
The intent of Credit 1.1 is to limit the use of potable water for landscape irrigation. The guideline to achieve this credit is to reduce potable water consumption by 50 percent of what a traditional irrigation system would use. The requirement is the use of high-efficiency irrigation technology or captured rain or recycled site water.
The easiest way to achieve Credit 1.1 is to design a low-volume or drip irrigation system. It sounds simple, but the designer must be aware of several issues that are inherent with the design of this type of irrigation system and know how to handle them.
• Properly design the drip system to use automatic flushing devises to carry dirt away from the emitters in the pipe.
• Inform the design team and developer/property owner of the ongoing maintenance effort required, including yearly inspections and filtration unit cleaning. The cost savings from these irrigation systems most often pays for the additional maintenance.
• Know where to place certain drip tube emitters that are installed above ground.
• Outline a manual flushing procedure as part of the system's annual maintenance.
• Investigate the use of existing as well as new products as they become available, including micro-spray and flood bubbler nozzles on pop-up spray bodies, weather-based smart controllers and others.
Credit 1.2
Water Efficient Landscaping: No Potable Use or No Irrigation
The intent of this credit is to eliminate the use of potable water for landscape irrigation. This credit is awarded to projects that use only captured rain water or recycled site water to eliminate water use for site irrigation (except for initial watering to establish plants), or those that don't install permanent landscape irrigation systems.
Credit 1.2 requires that no potable water be used for irrigation or that no irrigation system be installed at all. The easiest way to gain Credits 1.1 and 1.2 is to eliminate irrigation. However, eliminating the irrigation system will likely create problems for the landscape. If the property owner wants the landscape to look its best with minimal landscape maintenance, Credit 1.2 should be earned through eliminating potable water, not by eliminating irrigation.
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An example of landscape irrigation.
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To earn this credit, the irrigation must already be a low-volume system and Credit 1.1 must already be achieved. The introduction of nonpotable water source adds a new level of design strategy. The irrigation designer must be aware of the accessories necessary for this type of system and properly incorporate them into the design and specifications. To protect the public from using this water that is unsafe for human consumption, many irrigation manufacturers provide purple colored tops for sprinkler heads and valve box covers that have warnings on them to not drink the water.
Finding a nonpotable water source is not as difficult as you might expect. In some areas, municipal gray water can be used for irrigation. In other areas, rainwater collected in a variety of creative ways can satisfy watering needs — such as routing roof drains from a building into a storage tank or cistern — and rainwater is actually better for plants than municipal water sources.
If a large amount of water is needed, drainage from parking lots can be routed to storage facilities. To prevent plant damage, filtering systems or chemical treatments should be used to reduce vehicle fluids, salts from snow and ice removal, and hydrocarbons from pavement treatments. Other sources of nonpotable water include air conditioning systems that drain into a floor drain or excess water from humidifiers that is directed into a holding tank.
Liberty Property Trust's renovation of 245 Plaza — an existing office building in Brookfield, Wis. is a good example of a project that required the redesign of its irrigation system to achieve LEED credits. The facility had an existing landscape and irrigation system. Brookfield, Wisconsin-based National Survey & Engineering redesigned the irrigation system to reduce the potable water usage to less than 50 percent of its original design.
Low volume sprinkler heads were used to water all lawn areas that required irrigation. Drip irrigation was used in the new planting beds to get the plants established and will be discontinued within the next two years. The plant watering system will only be used when and if drought conditions warrant its use to maintain the natural growth and health of the plants. A weather-based smart controller, moisture sensors and rain sensors are also being used on this project.
Based on the location, type and size of the building, a non-potable water source could not be created. The irrigation system design was able to achieve the Water Efficiency Credit 1.1.
This office renovation was recently awarded a silver level of pre-certification from the U.S. Green Building Council, under the LEED Core and Shell Pilot Program. Pre-certification means that all of the construction LEED credits being applied for meet the program's intent and requirements. This project was one of the first LEED Core and Shell projects in the United States to receive pre-certification. Irrigation was one of several aspects that responded to LEED requirements. Others included erosion and sedimentation control, reducing heat-island effects on the site using shading, reducing site disturbance by designating more open space than was required by local ordinance, and promoting the use of hybrid vehicles.
The 245 Plaza project will be reviewed again upon completion. When it meets the requirements, the project will be certified as a compliant “green building” and registered with the U.S. Green Building Council.
A site's irrigation and landscape maintenance plan are critical to the success and ultimate sustainability of the development. The benefits of good irrigation are substantial and should not be overlooked, including the cost and time savings associated with maintaining the site, increased property values and the environmental benefits associated with water conservation.
Charles Stassi, ASLA, is a landscape architect and irrigation designer for National Survey & Engineering, a division of R.A. Smith & Associates, Inc.
©2005 France Publications, Inc. Duplication
or reproduction of this article not permitted without authorization
from France Publications, Inc. For information on reprints
of this article contact Barbara
Sherer at (630) 554-6054.
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