Spanish Valley Projects

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Spanish Valley - Monitoring Wells

    In order for Grand Water & Sewer District to drill and operate new culinary wells the State required them to also drill and monitor two other wells to make sure that they were not drawing down the aquifer. They tried to use battery operated datalogging probes at first, but the probes didn’t prove to work as well as they had hoped. 

   Sunrise was able to propose a better system. This system also included the data being automatically reported back to the exiting SCADA system for historical data storage.  This monitoring well did not have any local power so solar was a requirement. We designed and installed a RTU’s with a SCADAPack LP PLC from Control Microsystems. Since the site was solar and we needed to keep the cost of solar equipment as low as possible, we used the LP because it is their low power unit. We also programmed the PLC to only turn on the level probe every 15 minutes to keep battery usage to a minimum. The probe would be on for 10 second to allow the signal to settle and a level ‘snapshot’ would be taken and copied to a holding register to await being polled. We then interfaced the new RTU’s into the existing system.


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Spanish Valley - Spanish Valley Well Communications Upgrade

    If you have a system that controls pumps based on an analog level signal it needs to be free from interference that causes the signal to bounce.  The District had just that problem. Every analog point on one of their PLC's were bouncing around and causing the pumps to start and stop needlessly. The original integrator was called in to help solve the problem. They were unable to isolate the problem. They disconnected a few wires and the signal got better but it did not fix the problem. They then left the client to run his system in manual. I was asked to come and see if I would determine the problem. After a considerable investigation I determined that all the wires coming from the remote site had stray voltages on them and was messing with the neutral of the PLC. I was able to isolate that one site and the system began working again, except of course for the one site. As changes to the client’s infrastructure had been made, the contractor had dug up the cable connecting the chlorination building to a remote well several times in several places. The cable was repaired at the time but it appears that the splice failed to keep the water from leaking in. This caused voltages to stray into other wires within the same cable. I later found that a pair in the cable was being used to running a 120VAC control circuit. The cable was a communications cable with 20AWG wire. The communications cable was a poor design choice for running 4-20mA signals and a worse choice  to run 120VAC. 120VAC should never be run along side, certainly not in the same cable, with DC discrete or analog signals.

    The client and I discussed options and decided that a wireless connection would be most cost effective solution. I chose to use Phoenix Contact 2-Way I/O radios. These worked great for the direct wire replacement we were doing here. We did have to get the well site radio antenna up pretty high to clear the hill since we were using 900MHz radios that need direct line of site. I installed the equipment and did start-up.

It's very important to properly ground the antenna's coax cable with a grounding kit and an inline lightning arrestor to keep lightning from destroying your equipment.

 


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