As an irrigation consultant/designer, there are many methods we can use to minimize landscape water usage. Product selection, sprinkler spacing, plant specific zoning, and smart technologies to name a few. What we, as irrigation professions, do not have control of is the plant species and site layout. A plant species will require a certain amount of water regardless of an irrigation design. It may not be feasible to zone a lone shrub with a group of other shrubs that are on the other side of the property.
Recently ANSI/ASABE S623 "Determining Landscape Plan Water Demands" has been published. It is a total of 14 pages, with cover sheet. This is an excellent read for any Landscape Architect or designer, who would like to reduce the water needed to keep their designed landscape aesthetically pleasing.
Feel free to post comments or questions about this standard!
Thursday, January 21, 2016
Friday, January 8, 2016
Frequent or Deep and Infrequent, Which Watering Method is Best?
https://www.flickr.com/photos/asianturfgrass/8922147839/in/photostream/
Above is a link to a graph, illustrating the varying soil volumetric water content, over the course of a month. It compares two irrigated plots: One receiving frequent irrigation with short cycle times, and the other receiving infrequent irrigation with longer cycle times.
I came across this chart on Twitter. It received numerous replies and likes. The popular method, in the irrigation profession, is a deep and infrequent approach. The scientific theory behind this choice is to encourage deep roots, resulting in a more drought resistant and healthy landscape.
So, I am suggesting the chart is incorrect and we should ignore the results?
NO!
Then every irrigation system operator should change their method of programming, and irrigate more frequently with shorter cycle times?
NO!
This chart provides important data, and its results should be considered when programming an irrigation system. However, I do not think the chart provides a complete picture. It is important not to take a cookie cutter solution approach for every site. The irrigation system operator should work with an irrigation consultant, irrigation contractor, and landscape architect to establish the best baseline irrigation program. This should include site conditions, thresholds, goals, site uses, etc. The baseline program should be site specific, not a one-size-fits-all guess.
Above is a link to a graph, illustrating the varying soil volumetric water content, over the course of a month. It compares two irrigated plots: One receiving frequent irrigation with short cycle times, and the other receiving infrequent irrigation with longer cycle times.
I came across this chart on Twitter. It received numerous replies and likes. The popular method, in the irrigation profession, is a deep and infrequent approach. The scientific theory behind this choice is to encourage deep roots, resulting in a more drought resistant and healthy landscape.
So, I am suggesting the chart is incorrect and we should ignore the results?
NO!
Then every irrigation system operator should change their method of programming, and irrigate more frequently with shorter cycle times?
NO!
This chart provides important data, and its results should be considered when programming an irrigation system. However, I do not think the chart provides a complete picture. It is important not to take a cookie cutter solution approach for every site. The irrigation system operator should work with an irrigation consultant, irrigation contractor, and landscape architect to establish the best baseline irrigation program. This should include site conditions, thresholds, goals, site uses, etc. The baseline program should be site specific, not a one-size-fits-all guess.
Thursday, November 13, 2014
Annual Precipitation Trends Upwards for Pennsylvania
Below is a good article from the Extension Office at Penn State. It discusses an increase in annual heavy precipitation events, resulting in the state become more drought "tolerant."
http://extension.psu.edu/natural-resources/water/news/2014/penn-state-webinar-asks-2013-is-pennsylvania-becoming-drought-resistant#.VGNsnanJhKs.twitter
Does this mean we no longer need to irrigate our lawns in PA? Absolutely not. Our most recent summers have include extended periods of no or little rain. The lawns have needed supplemental water to prevent dormancy. Once dormancy starts, a lot of water is need to bring the lawn out of dormancy. Also, when lawns become stressed, this is also the time weeds start popping up. The amount of fertilizers and pesticides required can be reduced with a healthy lawn.
Does this mean we do not have to minimize the amount of water we put on our lawns? Again, absolutely not! Water conservation is important. But, if you do not feel strongly about water conservation, over watering your lawn is still a bad idea. It promotes shallow root development and disease problems. Just like people, too much of a good thing is also bad for grass.
http://extension.psu.edu/natural-resources/water/news/2014/penn-state-webinar-asks-2013-is-pennsylvania-becoming-drought-resistant#.VGNsnanJhKs.twitter
Does this mean we no longer need to irrigate our lawns in PA? Absolutely not. Our most recent summers have include extended periods of no or little rain. The lawns have needed supplemental water to prevent dormancy. Once dormancy starts, a lot of water is need to bring the lawn out of dormancy. Also, when lawns become stressed, this is also the time weeds start popping up. The amount of fertilizers and pesticides required can be reduced with a healthy lawn.
Does this mean we do not have to minimize the amount of water we put on our lawns? Again, absolutely not! Water conservation is important. But, if you do not feel strongly about water conservation, over watering your lawn is still a bad idea. It promotes shallow root development and disease problems. Just like people, too much of a good thing is also bad for grass.
Monday, November 10, 2014
Product Substitutions and Non-Proprietary Plans
Found in the Quality Assurance section of our specifications we include the following:
"Random product substitutions will not be accepted. The functionality of the irrigation design and system is based on characteristics of the products listed in these specifications and accompanied plan. Contractors wishing to substitute any product must submit, in writing, reasons for proposed substitution, product specifications, revised plan, and performance data to the Owner’s Representative and Irrigation Consultant. If written approval is granted, products may be substituted. Any products found during the final walk through, not previously approved, will be removed and replaced with an acceptable product at the contractor’s expense."
Similar products can have varying hydraulic characteristics from different manufacturers. Different flow rates, pressure requirements, and operating ranges. To minimize sizes due to pressure and flow requirements, a designer has to choose one product to make accurate hydraulic calculations. Changing products on a plan can require changes in other products, pipe sizing, scheduling, or water requirements.
A non-proprietary plan is almost an open ended plan allowing the contractor to select the products. The products selected must meet the minimum specifications, but can still have varying hydraulic characteristics. When designing a system, that a specific product is not called out, we need to design for the worse case. This can lead to higher pressure requirements, larger pipe sizes, larger valve sizes, etc.
The biggest selling point for non-proprietary plans is to avoid a manufacturer having the ability to charge more for their products. However, contractors typically buy irrigation products from an irrigation distributor. The manufacturer has no control of pricing per project, the distributor does. Most distributors carry multiple products from multiple manufacturers. A contractor has the choice to purchase the materials for each job from two or more local suppliers. This results in distributors trying to undercut the other for the sale. Usually on the same product.
When bidding from a plan, the biggest irrigation cost variable is labor. Most products, of similar quality, are close in price. Usually the savings is minimal when opting for one manufacturer over another.
"Random product substitutions will not be accepted. The functionality of the irrigation design and system is based on characteristics of the products listed in these specifications and accompanied plan. Contractors wishing to substitute any product must submit, in writing, reasons for proposed substitution, product specifications, revised plan, and performance data to the Owner’s Representative and Irrigation Consultant. If written approval is granted, products may be substituted. Any products found during the final walk through, not previously approved, will be removed and replaced with an acceptable product at the contractor’s expense."
Similar products can have varying hydraulic characteristics from different manufacturers. Different flow rates, pressure requirements, and operating ranges. To minimize sizes due to pressure and flow requirements, a designer has to choose one product to make accurate hydraulic calculations. Changing products on a plan can require changes in other products, pipe sizing, scheduling, or water requirements.
A non-proprietary plan is almost an open ended plan allowing the contractor to select the products. The products selected must meet the minimum specifications, but can still have varying hydraulic characteristics. When designing a system, that a specific product is not called out, we need to design for the worse case. This can lead to higher pressure requirements, larger pipe sizes, larger valve sizes, etc.
The biggest selling point for non-proprietary plans is to avoid a manufacturer having the ability to charge more for their products. However, contractors typically buy irrigation products from an irrigation distributor. The manufacturer has no control of pricing per project, the distributor does. Most distributors carry multiple products from multiple manufacturers. A contractor has the choice to purchase the materials for each job from two or more local suppliers. This results in distributors trying to undercut the other for the sale. Usually on the same product.
When bidding from a plan, the biggest irrigation cost variable is labor. Most products, of similar quality, are close in price. Usually the savings is minimal when opting for one manufacturer over another.
Wednesday, September 24, 2014
Too Many Heads / Sprinklers!
Looks like there are a lot of heads! Maybe too many?
Looks like there is a lot going on, any way we can clean it up?
These are the most common responses received, the first time an irrigation plan is reviewed. Irrigation plans are much more functional than visually appealing.
Distribution uniformity describes how even the water is being applied throughout an irrigation zone. If we place measuring cups in different locations, we want close to the same measurements of water.
One aspect of irrigation design, that affects distribution uniformity, is head spacing. A designer uses personal experience, manufacturerer's data, and site condtions to decide on the best head spacing. Approriately spaced heads results in a higher distribution uniformity. Heads spaced too far apart results in a lower distribution uniformity.
A low distibution uniformity rate results in a mix of over and under watered areas. A high distibution uniformity rate results in minimizing water use and maximizing plant health. Yes it is true that water in our area is viewed as being cheap, but replacing plants is not.
Thursday, September 18, 2014
Working with an Irrigation Consultant: How to Get Started
I was recently told that many engineers and landscape architects are not sure how to work with an irrigation consultant. Below are the best instructions to get started:
- Email us details about your project and include questions and concerns you may have.
- Call us.
Yes this seems overly simple, and we try to make it that way. You have enough to worry about with your project. We also understand that you may not have a strong background in irrigation. That is OK. That is why our company exists.
Wednesday, October 2, 2013
Irrigation Construction Inspections and Final Punch Lists: Don't Worry, I Saw the Sprinklers Work
A couple of months ago I followed up on a project we completed specifications and a design for. The contractor was currently installing the system. I asked if they would like us to complete a couple inspections during construction. The service was declined, and I was notified that the general contractor (GC) had it under control.
A week ago I received a request for a final walk though. The GC had already approved the system, but the owner wanted a second opinion. Most of the irrigation system was below ground at this point, but I was able to perform a visual inspection of the exposed components and view the system in operation. The following is a partial list of the items out of compliance with the design and specifications:
A week ago I received a request for a final walk though. The GC had already approved the system, but the owner wanted a second opinion. Most of the irrigation system was below ground at this point, but I was able to perform a visual inspection of the exposed components and view the system in operation. The following is a partial list of the items out of compliance with the design and specifications:
- Valve boxes were partially above grade creating a tripping hazard and becoming more susceptible to damage from mowers.
- Sprinklers nozzles were not as specified. An additional 900 gallons of water per day of operation is applied to the turf area than required.
- Two major pipe breaks were found. The system was designed to operate at 35 gallons per minute. Exact amount of water wasted could not be determined. Surrounding landscape and plant material will be damaged if not corrected.
- One zone contained different types of sprinklers. A portion of the landscape covered by this zone would be over/under watered. Possible loss of plant material.
These are just 4 out of the 21 items listed on the completed punch list. Most of the additional items relate to the reliability of the system. Inferior componets were used in lieu of products specified.
So how was this system signed off on and approved prior to this walk through? Because the GC saw sprinklers throwing water.
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