In twenty-odd years in this business, which Chet Sarsfield calls a disease … not a profession, a person should have learned something. I don’t know what happened in my case, but I’ll try to muddle through this anyway.

Synergy

All too often, there is an adversarial, rather ‘than a synergetic, relationship between the design of the Landscape Architect (L.A.) and the resultant design of the Irrigation Consultant (I.C.). Typically, the first time the I.C. sees the landscape plan is when the L.A. hands it to him, with the inference that the I.C. should be able to water it if he knows his stuff, and that the L.A. should not have to subject his delicate aesthetic sensibilities to mundane considerations of plumbing. The I.C. can, and all too often will, callously mumble to himself that he will be a good soldier and water the site one way or another, no matter how much it may cost the client. Does this sound a bit hyperbolic? Perhaps, but hopefully it illustrates that on occasion we design independently of one another.

The I.C. must be alert to what he can contribute that will help the L.A. reduce costs, not quality. In the best of all worlds, the L.A. would prepare his preliminary design and then stop!! He would then allow the I.C. to peruse the project and make his preliminary plan. Without stepping on the L.A.’s purview, there are a number of areas where the I.C. can reduce costs. How? Thought you’d never ask. ?

SIZE: The L.A. for the City of Phoenix, Dennis Scholtz, will not accept grass patches measuring less than 10 feet across. That is a deceptively simple, yet clever trick. He knows full well that small, odd shapes are impossible to water without overthrow, poor distribution, excess water consumption, and incidentally, excess cost. (The postage stamp parcels simply require too many heads per 1000 sq. ft.) On a 1 0-acre apartment complex, those little beggars can add up to thousands of dollars.

SHAPE: Much the same can be said for narrow, pointed, meandering turf areas. They are just too inefficient. As an example, the advent of the meandering sidewalk has created some interesting effects like advanced gutter-running. The width of the meandering parking strip turf varies from an impossible 1 foot to 20 feet or more. Your I.C. can suggest minimum and maximum widths for the resultant parking strip. Perhaps the sidewalk could be moved closer to the curb, that area planted to shrubs, leaving a turf area wide enough to justify the use of efficiently-sized heads.

Where sidewalks pass between buildings on apartments, condos, schools, etc., the positioning of that sidewalk can often be changed by only three or four feet. This often makes the difference between a three row system of 15’ heads or a four row system of 12’ heads. These situations repeat themselves hundreds of times across a large condo and the contractors are bidding on a per head basis. The I.C. will pick this up in his preliminary. (He has the perpendiculars of equilateral triangles rattling around in the back of his head.)

DISSIMILAR PLANT TYPES: Grouping plants of widely varying water requirements in the same bed makes it impossible to water correctly, or at least economically. Building two or more systems on top of each other to handle these wide variations is prohibitive. As we perfect drop irrigation, we can accommodate these variations somewhat by using emitters with varying flow.

ISOLATED OR DISPERSED PLANT TYPES: To scatter plantings having special water requirements indiscriminately about the site can cause complex design solutions and “fear factor” bidding. Mass enough of any similar water requirement plants in any one place to make up a respectable size valve section. (Some valves and/or pressure regulator equipment will not handle small flows.)

These last two items are why it is productive to bring the I.C. in during the preliminary stages. Give him your preliminary plant pallet. He can list plant water use requirements and return it to you for your use in grouping your plantings. (He is going to have to do this before he can design anyway, so let him do it early so you will have a guide.) In the case of a drip system, the I.C. would return your plant pallet (much reduced for this article) looking something like the ?EUR??,,????'??Emitter Schedule” which follows.

Notes:

1. Perhaps substitutes could be found for heavy drinking Oe & Pf. That done, all plants on the palette can be watered on one valve section in 3 hours. A palette which avoids extremes of water requirements eliminates the need for dual or triple sections in the same trench ($$$$!).
2. Shrubs, vines or ground cover may fall into either high, medium, or low water requirement.
3. Obtaining precisely the required flow is never possible. The above are close considering the controversy over plant water requirements, the limited emitter flows available and the variations in site conditions.

Trees Blocking Sprinklers:

Invariably, trees end up in front of sprinklers requiring extra heads to avoid the blocked sprinkler patterns. If this repeats over and over again on that 10-acre condo, the costs multiply. The I.C.’s preliminary could show head locations, thus allowing the L.A. to avoid them. Or, the L.A. could allow a note such as: “Field, adjust tree locations equadistant between sprinklers.” In most instances, this will not affect the aesthetics whatsoever. Yeah, we’re messing with your design but didn’t you say you needed to cut costs while holding up quality?

Adequate Data:

The biggest mistake an I.C. can make is to start too soon. Often, data drifts in piecemeal. After too much time has been invested, or it is too close to the deadline, a whole new understanding of the project emerges. On even the smallest project, the I.C. must do a certain amount of master planning to balance quality and cost among the many design options. If conditions are in such flux that changes are unavoidable, second and third preliminaries may have to be passed between L.A. and I.C. I have seen color accent changes, seemingly minor to the L.A., that have a ripple effect on the irrigation design which may cause every valve, clock and main line to change! Late changes are invariably expensive ones.

Master Plan:

On projects of any size, encourage the owner/client to bring in the I.C. for a master water plan. Our world is full enough with projects which just “grew like Topsy” without prior planning. Pressure and capacity problems abound; unnecessary meter and backflow prevention costs are incurred; control systems become unmanageable; each new phase has a new design concept and different criteria; maintenance and management suffer. Unfortunately, the owner rarely realizes how much the lack of a master plan will cost him over the years.

Bill Derryberry is owner of Derryberry Irrigation Consulting, Scottsdale, AZ. He is author of “Trouble Shooting Irrigation Control Systems”. Bill states that “having worked with soils, plants and irrigation for 32 years, we have learned where the problems are,”?EUR??,,????'??? and how to solve them. Call him @ 602-423-0542