Golf Course Water Supply

[getstuff]

Hello Everyone,

Long time browser, first time poster.

We are working on a new golf course and residential development and are responsible for providing the irrigation water for the golf course(s). We will not be designing the course irrigation system, only the water supply.

We have been told by the golf course designers that the water demands will be 33.9 l/s monthly peak demand, and 57.9 l/s daily peak demand. Water will be supplied by a well that can only pump at the rate of 33.9 l/s. We will also use stormwater runoff when it is available. However we think that becuase the stormwater source is not relible, it will only be used as it is supplied. That is to say: if stromwater is available, the pumping can be reduced. But, it is only a bonus and will not be relied upon for sizing the system.

So, my question:

1)The peak daily demand averaged over a month will be equal to the peak monthly demand. Thus, in a worse case senario, the course will require 57.9 l/s for 1/2 of the month (say 1st to 15th) and no water from the 16th to 30th. Thus averaging to the peak monthly demand.

Given this, since the pump can only provide 33.9 l/s, there will possibly be 15 days per month that the pump cannot keep up with demand. So, in order to provide this extra needed water, we will have to draw from resevoirs.

The extra water needed is (55.9 l/s - 33.9 l/s) = 24 l/s.
Then * 16 days (one extra for the 31 day months) = about 33100 m^3 of extra water.

Is this over simplified? Should we look into the weather and maximum number of potential watering days in a row?

2)There will be multiple storage reseviors around the site in addition to the stormwater treatment/detention ponds. We plan to pump water from the well and the stormwater ponds into the resevoirs.

Now, should the resevoirs be connected to each other linearly in series so that Pond A draws from Pond B that draws from Pond C .... untill distribution to the course?

Or, should we use some type of parrallel connection system?

Or, should we develop a "zoned" system were each pond only distributes water to a localized area around the pond?

What do you all think,
Thank you in advance for your thoughts.

 

[DMcGrath]

You should base your analysis on a water balance (total volumes) rather than flow rates. Figure out how much the course will consume in a month, then figure out your supply (well + storage). I assume there will be times during the day when the course is requiring no water (playing time, middle of the night. etc.) and during these times your well can be replenishing the supply. Let's hope your well has long-term potential!

If you are planning to store storm water in reservoirs (I assume open ponds), don't overlook evaporation losses. If you are in an arid climate, they could be significant. Percolation through the bottom could be a factor as well. Plan for the worst, and then hope for the best.

As far as the layout goes, this will really need to be discussed early on with the irrigation designer whether they intend to have one or multiple water intakes for their system, how many zones they want to run at a given time, etc.

I wouldn't put much reliance on the historical weather data. Like you said, the storm water is a bonus.

 

[atook]

You may find that the peak demand is over a watering window of 8 hours. As DMcGrath mentions, you’ll need to calculate the daily peak usage volume, then divide by the watering window to figure out the flow needed. I would calculate the daily requirement based on evapotranspiration rates for the area. Remember that you may need 57.9 l/s over eight hours, but you can use the 33.9l/s over 24 hours. Typically there is a drawdown effect on the reservoirs overnight (watering window) that the pumps replenish throughout the day. The drawdown is not good for clay based liners on the reservoirs, since it cycles it through dry/wet.

Regarding storage and distribution: I would keep it to 2 pumping distribution systems at the most (front & back 9?) Try to keep one pumping system per distribution system, instead of coming off of multiple reservoirs, as balancing pump stations can be difficult, resulting in asymmetrical wear between stations. The courses I have designed typically pull out of one reservoir, with one pumping system feeding the irrigation mainline. That being said, you’ll probably want a linear (series) connection between reservoirs.