In our last section we found we had a well based problem and called a local plumber. You should read this first to get all the particulars.
The plumber works fast, and I barely have time to piece what he is doing together (he isn't explaining trust me.) First he checks the pressure tank like I did, he doesn't even bother to isolate, the pump would be continuously running if there was a leak. (he has done this deductive work before obviously) Next he puts shuts the pump off with the breaker and lets the tank drain down to about 20 PSI. He turns it on and watches the rate in which it fills. It takes a looooong time to fill. Here is where his experience pays off. So far he is confirming my fear that something is wrong with the pump; a $1000 proposition minimum. Just as I'm about to start wringing my hands he goes to his truck and finds a Amp meter. This time he repeats the test for filling and watches the amps on the pump. When the pump starts it has about 1hp load on it (its a 3/4 hp rated pump which means that its working hard), then after a few seconds of work the tone of the pump changes and the draw from the pump plunges to nearly nothing. What does it mean!!!! The next move Mr. Plumber makes is to grab a Powers electric well sounder. Okay...
The sounder performs a few tasks. First it finds the depth of the Well (maybe), then the depth of the pump, and finally the static depth of the water level. The water level is found through conductivity in the water. when the metal sensor on the end hits water in closes the circuit and a chime on the sounder goes off. Then Mr. Plumber continues lowering the sounder till he hits bottom. He isn't sure how deep the well is because he thinks things are hanging up on the the pump. So our pump at least 156 feet deep and the static waterline is 146 ft deep. Mr. Plumber knows this is not really right, but Jonathan doesn't catch on right away.
"You barely have the pump submerged!!" He exclaims, "You only have 10 feet of head on that pump so your pulling down the water level inside the well and then you have to wait till it slowly refills from the aquifer.
The power of math tells me later that I barely have 120 gallons of water available for pumping, and don't forget that as the pump pulls the water level lower its getting less help from the head pressure till the water level is equal with the pump! the best sprinkler estimates tell me that i'm using around 12 gallons a minute.... this means in 10 minutes the pump is out of water, but more importantly the pressure needed to sustain the pump at 45 PSI isn't going to happen at but half that depth. There is only 5 minutes of pump-able water on a perfectly non leaking system. Ut-oh.
Lets go through the math together. lets say the inside diameter of the pipe is 6 inches. The formula for the area of a circle is Pi(r squared) or 113 square inches. 113 inches x (8ft deep x 12 inches in a foot) = 10,848 cubic inches of water. which when divided by 12 is 904 cubit feet of water. And when divided again by 7.48 cubic feet of water per gallon is 120 gallons
Mr. Plumber suggests he is going to send his boys out here to put in another length of pipe, also to extricate his sounder which is tangled. This means the pump is going another 20 feet deeper. This means 302 gallons of water standing on top of the pump. Okay that's better. At a rate of 10 gallons per minute usage were talking about 30 minutes of water, so in reality 25 minutes of watering time because of pressure. Better. but there are problems with this too. Lets just see what the crew says when they look at the pump well and everything else.
After the crew arrives coming out to extricate the owners sounder they end up pulling the entire pump assembly up and out we have some cool photos, and some new less cool info.
The pump was purchased and installed in 1990 making ours 26 years old. Which is amazing according to the crew leader. It is also a 1 HP motor on a 10 Gallon Per Minute pump. This also means our well report was wrong when we purchased the house. Reality is that we are probably only getting 8 GPM out of the pump; which with our lawn's thirsty layout creates a problem. The crew leader lowered the pump the extra 2 feet, which he said was definitely worth the bother. So now we have 151-ish gallons of water and 10 feet of head pressure. Its not ideal but the extra 30 gallons and pressure should help.
So our theoretical sprinkler run time is 18 minutes at 8PM. Which means its more like 15 minutes. This might be doable for at least the back yard and possibly a sliver of grass in the front yard. It will not be enough for a 15,000 ft yard that requires 9,300 gallons of water a week. To achieve this rate we would have to completely empty and replenish the well 62 times to complete this watering cycle weekly, or roughly 9 times a night for a week.
Time for a new plan for our home exterior.