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:

1. Valve boxes were partially above grade creating a tripping hazard and becoming more susceptible to damage from mowers.
2. Sprinklers nozzles were not as specified.  An additional 900 gallons of water per day of operation is applied to the turf area than required.
3. 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.   
4. 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.

What Brand Should I Use?

Early in the irrigation design process, brands and models of irrigation components are selected.  Sometimes this is dictated by the owner of the site.  Other times I am asked for recommendations.  There are some products that are unique to a manufacturer.  There are also a lot of similar products that all manufacturers offer.  So how do I choose?  Below is just a brief list of considerations before I recommend a specific product:

• Price:  Let us get this out of the way first.  It is the first thing that most bring up.  While I do not think this should be "the" deciding factor, it is a factor.  If there are two or three products that get the job done, and are reliable, I usually go with the lower priced item.
• Location of the project / Product availability:  There is a lot of disparity between the number of irrigation distributors in New Jersey vs. Harrisburg, PA vs. Washington D.C.  Some products available off the shelf in D.C. may need to be special ordered in Harrisburg.  When possible, I try to stick with what is locally available.
• Local contractor experience:  Contractors' experiences with certain irrigation technologies can vary greatly in our area.  This is not a slight to any contractor.  The differences in level of experience can be a result of many factors.  Maybe a locally based sales rep pushed it hard in an area, or the product was more practical for local projects.  A prime example of this is when two-wire was first introduced.  It was very popular along the beaches in Maryland and Delaware.  It provided a wonderful solution to the phased in construction associated with many of the large development projects, and was quickly adopted.  There was little benefit and cost savings to be had on the smaller irrigation projects in Central Pennsylvania.  The result was a slower adoption rate for many local contractors. 
• Product performance / Site conditions:  Every site has unique conditions.  Some products are a better fit based on their specifications and/or performance.  
• Reliability
• Local support:  Some people manufacturer's have in the fields are better than others.  If they have a track record of being unresponsive it is usually best to steer clear of their products.  No manufacturer is immune to occasional manufacturing problems.  Having good people in the field helps correct these problems quickly with minimized issues to the end user.
• Past product experience:  From 1998 to now I have used many products on numerous projects.  Many good ones, and some I have learned to avoid.

So how do you select which products to use?

Conserving Collected Stormwater

It has become more common in our area to use an irrigation system as a way to dispose of collected stormwater.  On paper this sounds like a very environmentally friendly solution.  However, many engineers and architects are failing to see the the full potential of installing an irrigation system.  Their narratives discuss disposal of the water and dosage information.  One could easily confuse their irrigation narratives with that of an on-site septic system.  It is very clear that their goal is to get rid of the water as soon as possible.  However, is this sustainable?  If we install solar panels, and we have multiple sunny days, should we turn on all the lights to get rid of our abundance of collected electricity?

On a recent project, we were able to irrigate most of the site, with only collected stormwater.  The irrigation system is programmed to operate above the plant material ET rates and below maximum soil loading rates.  The basin will be completely drained once a year by the irrigation system.  We estimate this to occur in October.  If the quick disposal method were followed, we would irrigate at the maximum soil loading rate.  We estimated that we would run out of water 4 months of the year, probably resulting in some brown turf.

Which way do you feel is more sustainable and looks holistically at site design?

Final Irrigation Walk Through

So you are the project lead and you were just told that the irrigation system is complete.  The budget is tight, so you decide that you can handle this task.  You think to yourself:  "Hey, I know enough to be dangerous.  It is just irrigation.  I can tell if it throws water!"

The irrigation contractor walks you through the system.  Shows you the backflow preventer, maybe opens a valve box or two, maybe a pump station, controller, and then turns on and off each zone.  You see the sprinklers shooting water and think it looks great.  You sign off on it, and the contractor gets paid.  The project is completed.  You made sure your client got what they paid for, right?

• Did you check to see if the pipe was the proper size?
• Check pressure available at the distal sprinkler?
• Inspect solvent-weld joints to make sure solvent and primer was not running down the pipe?
• Did the contractor use primer and/or lube?
• Teflon tape?
• Proper schedule of fittings?
• Were the thrust blocks installed against undistrubed soil?  Did they open the bag and mix the cement?
• Was the controller properly programmed for the climate in your area?
• Was the control wire and splice suitable for direct bury?
• Are the valve boxes dry?
• Are the valve boxes and sprinklers installed at grade?
• Is the drip tubing properly secured and covered?
• Are different nozzles used for different arcs?
• ETC.....

The standard nozzle for most mid-range rotors emits 3.0 gallons per minute.  If a zone has one rotor set at 90 degrees and the rest set at 180 degrees the nozzle on the 90 degree rotor should be reduced to emit 1.5 gallons per minute.  If nozzle is not changed, that one sprinkler uses 1.5 gallons per minute more than needed.  If the zone is scheduled to operate 20 minutes daily, then the irrigation system uses at least 30 gallons more than it needs to daily.  That would result in 930 gallons of wasted water for the month of July, for that one zone.

If this is the result of just one misplaced nozzle, what is the effect of the other items mentioned?

Reducing Water Use on Synthetic Turf Fields

There is no typo in the title.  Synthetic turf requires less than its natural counterpart, but does not eliminate water use.  Cleaning, cooling, and improving playability is just a few things water is used for on a synthetic field.  Water is usually applied to the field with hoses, water canons, traveling sprinklers, and/or underground sprinklers.  

Below is a link to an article that appeared in SportTurf discussing a recent renovation to a field at Princeton University.  The renovation included installing underground sprinklers to wet the field prior to field hockey games.  With the new system, it takes 1,200 gallons of water to saturate the field.  Previously they applied water using a traveling sprinkler (water reel).  To saturate the field with the traveling sprinkler it required 12,000 gallons of water.  Again, that is not a typo!

http://read.dmtmag.com/i/96775/21

The Solution to All of Our Environmental Concerns!

Does it help the environment installing synthetic turf, in an area where there is an abundant water supply, and has had a healthy stand of natural turf for years?

Should an athletic field be kept as natural turf if it is mostly dirt and mud from over use?

Is consuming organic produce, that needs to be transported 700 miles, more environmentally friendly than conventionally grown produce from a neighboring farm?

Does the energy saved from a light bulb made in China compensate for the fossil fuels burned to get the bulb to your house?

Are the same maximum turf limits recommended in Arizona best for a site in Pennsylvania?

I could keep going.  At the bottom of this posting there is a link to another blog.  It does not talk about irrigation, water conservation, landscaping, or site development.  What it does is challenge us to think.  We as design professionals are heavily marketed by companies offering all types of "green" solutions.  What is best for our clients and the environment is not always the latest and greatest, and does not always result it a pretty plaque in a lobby.  Just something to think about.

http://www.totallandscapecare.com/the-truth-about-diesel/

Rainwater Harvesting and Water Conservation

In early November I attended the Irrigation Association’s National Irrigation Show and Educational Conference.  Attendees have the opportunity to attend educational seminars, and to see some of the latest products in irrigation.  Most new products offer water conservation improvements from those utilized in the past.  One heavily marketed water conservation method is rainwater or stormwater harvesting.  This is the practice of catching, and storing, water that would typically be lost to runoff from non-pervious surfaces such as roofs or parking lots.  The stored water is then able to be utilized for non-potable uses such as irrigation.  This is a wonderful way to conserve water, but does have one major downfall.  The cost of providing storage for this captured water is expensive, and the return on investment period is typically longer than many like to see.  Some projects can justify the added expense, because it is part of the stormwater management plan, LEED certification, and/or the organization feels strongly about water conservation.  However, only 5% of our projects fall into one of these three categories.  Does this mean that unless one spends large amounts of money that water requirements for irrigation can not be reduced?  Absolutely not!  Below are several inexpensive methods to reduce landscape water use:  

• Good head to head coverage.  Sprinklers should be spaced so that the water stream from one touches another sprinkler.  This provides good uniform distribution of water throughout the irrigated area.  This is the way the manufacturer’s design the sprinklers.  Stretching the spacing or eliminating a sprinkler reduces distribution uniformity.  The result is longer run times to compensate for the dry areas, and higher water use.  
• Proper sprinkler inlet pressure.  Too much or too low of water pressure has a negative effect on sprinkler performance.  One produces a fine mist that is lost in the wind and evaporation.  The other provides a beautiful green donut pattern in turf areas.  Either results in a higher water bill.  
• Reduced flow rate spray nozzles.  Old style spray nozzles, fixed and variable arc, have a very high flow rate.  A flow rate much higher than most soils can handle resulting in unwanted run-off.  Most manufacturer’s now make spray nozzles that water at a much more manageable flow rate.
• ET-based / soil moisture sensors and smart controllers.  This technology has received a lot of negative and positive publicity.  A lot of the negative opinions of these controllers and technologies are related to the area of the country one resides in and sometimes mis-management.  My opinion concerning smart controllers and sensors are mostly positive.  Our area of the country “supplements” water requirements for landscapes.  Typically controllers are set in the spring for water requirements in July and turned off in October.  Water requirements are greatest in July.  Having a controller reduce watering times, based on current weather or soil conditions, has a huge potential to minimize water use.
• Rain sensors.  Watering is suspended when a pre-set amount of rainfall is received.  Rain sensors or switches are so inexpensive I can not think of a situation when one should not be installed.