November 25, 2020

Groundwater Level Monitoring & Piezometric Pressure

With the ever-increasing population and depleting resources, it becomes extremely critical to take care of the current resources to ensure a better, more sustainable future. As the human population is on a continuous rise, there have been concerns about not having enough resources in the future for the generations to survive with ease and comfort. One such resource is water, which is heavily exploited, polluted, and not paid enough attention.

With the ever-increasing population and depleting resources, it becomes extremely critical to take care of the current resources to ensure a better, more sustainable future. As the human population is on a continuous rise, there have been concerns about not having enough resources in the future for the generations to survive with ease and comfort. One such resource is water, which is heavily exploited, polluted, and not paid enough attention.

Today, we are particularly focusing on Groundwater, which is an exceptionally important resource. Groundwater is responsible for irrigation, drinking, and even industrial use. As we are focusing on sustainability, it is important to monitor it accurately; either manually or automatically. In fact, it has become a mandatory requirement at various places all over the world to monitor and recharge the groundwater level, also known as the water table.

Before we forward, let’s have a look at why groundwater is important.

Why is Groundwater important?

Let’s face the obvious answer; water is essential for survival, right from cooking, cleaning, to ensuring a healthy working of our body. Groundwater is responsible for 30% of all the world’s freshwater while the rest of the 70% is bound up in snow and ice in the mountain or polar regions, and 0.2% makes up for the lakes, streams, or rivers. Even the rivers and lakes are largely supported by the groundwater so it won’t be wrong to say that almost all the water we use for essential purposes comes from the groundwater.

Apart from being the only resource from where we get our water needs, it also supports the lakes and rivers through the drier months, and seeps through the river bed, providing the home for all the wildlife and plants that live in the water.

It is also essential to notice that groundwater requires less treatment than the river water, making it safer and economical to be consumed. As it flows through the soil and rocks, the foreign objects like pollutants and impurities are naturally removed.

Now that you understand the importance and significance of groundwater, you might have a glimpse of how important groundwater monitoring is.
Next, we are going to talk about the different instruments that Encardio Rite offers for a seamless and efficient groundwater monitoring. These include the most sophisticated to the most simple ones, to be used either manually or automatically.

Let’s get started.

Manual Groundwater Monitoring

Standpipe for Groundwater Monitoring (Model EPP-10SP)

Encardio Rite Model EPP-10SP Standpipe is a geotechnical instrument curated for the measurement of groundwater level and its variation over a period of time. Equipped with a range of 3m long PVC riser pipes which are approximately 50mm in diameter, the instrument also features an in-built socket at one end for jointing.

The intake point of the standpipe makes use of the same diameter PVC slotted pipe, which is fixed at the bottom of the pipe assembly. The slotted pipe is coated with geotextile to limit any ingress of solid particles, with the bottom end of the pipe being plugged with a suitable PVC Cap.

Once done, the sensor is placed in a 100mm diameter borehole that is drilled into the soil/foundation at a level deeper than the maximum expected groundwater level. The Groundwater moves into the riser pipe from the slotted end and reaches the same level as it is equal to the groundwater at that particular location.

Have a look at the image below to understand the assembly and installation layout of the Standpipe.

Casagrande piezometer for monitoring piezometric pressure (Model EPP-10)

Before we start with how the Casagrande Piezometer works, let’s see how piezometric/pore pressure aligns with groundwater monitoring.

The Pore Water Pressure is described as the pressure that is endured by the water contained in the pores of earth materials, concrete structures or rock. The measurement of pore water pressure, also known as piezometric pressure, is important for groundwater monitoring. This allows us to determine the level and flow pattern of the groundwater.

Encardio Rite Casagrande Piezometer is used for the measurement of piezometric pressure at any point below the ground surface.
The pore water pressure drives the water to flow in through the piezometer tip. This leads to an increase in the riser pipe until the pore pressure is equalized by the head of water in the riser pipe.

| Also Read: What Are The Different Types Of Piezometers? |

Water Level Indicator (Model EPP-10/6)

Encardio Rite Water Level Indicator is specially curated to the accurate measurement of the depth of water surface from ground level in a standpipe, well, borehole, or with the Casagrande Piezometer Installation.

The water indicator is a robust, lightweight, and extremely efficient to use, with its battery operation, on and off switch, buzzer, LED, flat cable, winding reel, and a carrying handle.

Water Level Indicator

The water level sounder probe is dropped from the surface with the assistance of a connecting twin conductor flat cable for noting the observations. As soon as the water in the borehole/well touches the tip of the probe, the indicator gives an audible and visible signal. The depth of the probe from the riser tube top rim can be read off the graduated marks on the cable.

Electronic Monitoring

Model EPP-30V and EPP-60V for ground monitoring water level or piezometric pressure

Encardio Rite offers two different models for the accurate measurement of pore pressure or water level. Model EPP-3V and EPP-60V are vibrating wire sensors designed for the exact estimation of pore pressure in a borehole depending upon how the sensor is installed. The instrument also comes equipped with a thermistor, that is used to estimate the water temperature.

Model EPP-60V Low-Pressure Sensor is advised to be used where the maximum hydrostatic head, i.e, the height of the water above the sensor) is less than 7m. On the other hand, Model EPP-30V makes it better for higher hydrostatic head and pressures.

Encardio Rite sensors are incorporated with the latest vibrating wire technology that provides remote digital readout or automatic data monitoring of water level or piezometric pressure in boreholes, standpipes, embankments, soils, earth fills, etc.

These sensors are equipped with a vibrating wire and coil magnet assembly securely placed in a stainless steel housing. The enclosed housing is an electron beam welded to the pressure sensing diaphragm. This leads to a vacuum of around 1/1000 Torr inside the EPP-30V sensors, thus making it impossible for water or corrosive material to find its way inside the sensor.

For the EPP-60V Model and the EPP-30V sensors that are used where the hydrostatic head is less than 15m over the sensor’s diaphragm, there is a slight difference. On the glass to metal seal, two small openings are provided and a special model CS-1102 vented tube cable is used for these low capacity sensors.

Also Read: How Is Vibrating Wire Piezometer Installation Done? |

The cables that connect the inside of the sensor to the outside are shielded and have two vent tubes running through it. This is carried out to ensure that the readings remain unaffected by any fluctuations in the barometric pressure; leading to accurate data.
Moreover, the open end of the vent tubes land in a moisture trap assembly placed on top of the borehole, thereby restricting any moisture from entering the tube or the sensor.

Since these sensors work in close proximity and keep in touch with the water, they need to be resistant to rusting and corrosion due to the multiple impurities found in the underground water. For this reason, Encardio Rite provides sensors that are constructed from robust stainless steel, which can easily bear it all.

The sensing diaphragm is equipped with a low air entry value flat ceramic filter with a pore diameter of 40-60 microns. The water that enters through the internal pores or rock formations, soil, etc flows through the filter to pressurize the diaphragm.

The superiority of the Encardio Rite diaphragm type sensors for these applications is unquestionable.

Model EDI-51V Read-out Device

Encardio Rite Model EDI-51V is a microprocessor-based readout unit specially designed for the range of vibrating wire sensors. It is manufactured to store calibration coefficients of almost 500 vibrating wire transducers, thereby allowing the value of the measured parameter from the transducers to be presented in proper engineering units. The vibrating wire indicator makes use of internal non-volatile memory to keep up to 4,500 readings along with the date and time of the measurements. Moreover, it can also display and record the temperature of the sensor. For ease access, the stored readings can be uploaded to a host computer with the help of a serial interface.

The readout indicator is equipped with an internal 6V rechargeable sealed maintenance-free battery. A completely charged battery will give an uninterrupted 60 hours of operation, and you can quickly recharge it with the battery charger provided.

Read Out Device

The Read-out unit is carefully enclosed in a splash-proof plastic moulded enclosure designed with weatherproof connectors for the seamless connections to vibrating wire transducer, computer for data transfer and the battery charger.

This was all about groundwater monitoring and the solutions provided by Encardio Rite. Hope this was helpful and informative.
If you have any doubts or questions, feel free to comment below!

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