Remote Water Well Metering
The Edwards Aquifer Authority (EAA) Act stipulates that all municipal, industrial, and irrigation water wells be classified as non-exempt wells, requiring a water withdrawal permit in order to be put in use, and that any such well is required to be metered. The EAA is mandated to keep an accurate account of water being discharged from the aquifer. Meters that are integrated in the discharge line are used to monitor usage from permitted wells. Traditional meters have some disadvantages that make using a remote system a more logical and efficient path for water use accountability. Beginning in 2004 the EAA began designing a remote meter to replace analog meters on a voluntary basis.
An EAA permit classifies the use and quantity of water that can be withdrawn from the aquifer. Meters are installed on all permitted aquifer wells to keep track of the annual water usage. As the well pump is turned on and water begins to flow, it passes through a turbine within the meter which converts revolutions to its unit of measurement, using an apparatus known as a Hall Effect spinning rotor. The reading has to be manually recorded by someone physically going to the well location and taking the meter reading.
Permit holders are required to record their meter readings and submit them annually to the EAA. EAA staff visit each permitted well annually to check the meters to insure they are operating correctly and to collect spot readings. During times of critical period EAA rules require permit holders to reduce their withdrawals from the Aquifer, and take monthly meter readings. Unfortunately, there are occasional discrepancies between the EAA and the permit holder’s data. These irregularities can be caused by human error, misreading of the meter, malfunction of the meter, or even in rarer circumstances, tampering of the meter.
Water Well Meter Device
Photo: Remote Meter Communications Equipment
The EAA implemented a remote well metering program to mitigate the issues caused by its meters. The EAA’s remote meter device is designed to limit human error, reduce manpower, and eliminate mechanical malfunction or tampering while maintaining the integrity and function of the original analog meter. A retrofitted, non-invasive sensor array was developed by the EAA to convert existing meters into remote meters. To make the conversion, a sensor ring with a pulse output device is fitted around the existing Hall Effect spinning rotor. The pulse output device can detect the distortions in the magnetic field as the meter spins. A computer program then converts pulse output into gallons used. Because no modifications were made to the existing meters, the traditional method or reading the meter can be used to verify the accuracy of the remote meter reading. Additionally, a three-way accelerometer, housed within the retrofit assembly, can detect the vibrations of the running well pump. If the remote assembly is detecting vibration but not water usage an alarm is generated and sent back to EAA staff. A follow-up site visit can be conducted to confirm meter errors or tampering.
Early on in the program, data generated by the remote assembly was transmitted via radio signal to a near-by EAA vehicle. While this process eliminated the need to physically enter the well owner’s property, it still required nearly the same amount of man hours and resources. In recent years this system has been replaced by transmitting the well data, in real time, to adjacent mini-relay stations, and established communication towers. The well data are transmitted though the tower network and back to the EAA headquarters for further processing. EAA staff has also implemented a new Programmable Logic Controller (PLC) that can store several months of data, meaning the EAA can access meters that are outside the current wireless infrastructure as well as not losing data if a wireless tower was to go offline.
To independently validate the equipment developed by EAA staff, the sensor array was tested for accuracy by a third party consultant. After a couple months of testing it passed without issue. Many of the devices matched perfectly with their analog counterparts, while the older meters, tested with +/- 0.25% tolerance.
This remote metering program effectively eliminates both the need for permit holders to take monthly readings at the well site and the required annual inspection by EAA staff. The remote meters have been successfully installed and tested on a volunteer basis by irrigators in the western portion of the Edwards Aquifer.
Permit holders who would like to convert their meters to the new system can contact EAA permit staff. Additionally, irrigators who wish to participate in the Voluntary Irrigation Suspension Program Option (VISPO), an Edwards Aquifer Habitat Conservation Plan (EAHCP) initiative, are required to have existing manual meters converted to remote meters.