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Long lasting, cost-effective solutions for water-related applications, integrating our customers’ know-how with KELLER’s H2O-expertise.
Since 2007 the Polish Geological Institute has been using almost 200 pieces of KELLER DCX-22 data collectors. As the monitoring process needed to be automatised, the remote data transmission unit and data logger GSM-2 seemed to be the perfect solution. The data collectors are mostly placed in custom-built wells called piezometers. Thanks to its highly robust mechanical construction (waterproof stainless steel housing) and its very low power demanding electronic it was a perfect solution for the customer's needs.
The GSM-2 module allows the data transfer via GSM i / GPRS i by using SMS, FTP i or Email communication. Furthermore, the collected data is saved in a buffer with a capacity of 57’000 samples, which additionally increases the security of the collected data. The barometer installed inside allows using a capillary free, extremely stable absolute pressure sensor for water level measurement.
The level probe used in this application is a PAA-36 X W with a total error band of 0,05% (0…40°C) and water temperature measurement carried out by an optional Pt1000 sensor reaching the 0,1°C accuracy. The Low Voltage (LV) electronics requires a voltage supply of only 3,2V, which guarantees a battery life of many years. The lack of capillary hugely increases the reliability of the system eliminating the humidity problems.
At this moment there are 350 ground water monitoring systems based on GSM-2 modules installed in the whole country, sending the information on water level and temperatures directly to the main control station and database located in Warsaw.
Cone penetration testing is a Dutch invention (late 50s) and has been used for many years as an economical method for soil investigation. These tests give a good picture of the soil structure and capacity of the different soil layers. They are used globally in all weak soil areas where significant changes in soil payload take place due to drilling, building etc.
Cone penetration testing truck Cone pressed into ground
The cone penetration testing results are illustrated in a graph with horizontally the cone resistance and vertically the cone depth. The sensors in a cone penetration testing cone measure, beside the soil resistance, the inclination of the cone, the friction ratio, soil temperature, conductivity and water tension. For this last parameter our PA21Y is used.
When building houses or a highway in weak soil, for example on former swamps or river sides / deltas, the soil must first be compressed in order to avoid sinking. Soil is build up of granulate and water. For building purposes, i.e. putting a payload on the ground, the soil must be compressed before one can start to build.
Cone penetration testing report and a testing cone
If the soil is compressed too much, the groundwater cannot find a way out quick enough and hydrostatic pressure of the ground water will rise too much resulting in unwanted soil movements/floatation - complete dykes or buildings can float away! This phenomenon is called soil liquefaction, meaning that the soil behaves like a liquid. It also can occur at earthquakes. Maybe you know this phenomenon already; quicksand is a form of soil liquefaction.
The effects of soil liquefaction in built-up areas can be extremely damaging. Buildings, whose foundations bear directly on sand, which liquefies will experience a sudden loss of support. This is turn will result in a drastic and irregular settlement of a building causing structural damage, including cracking of foundations and damage to the building structure itself, or may leave the structure unserviceable afterwards, even without structural damage.
Where a thin crust of non-liquefied soil exists between building's foundation and liquefied soil, a "punching shear" type foundation failure may occur. The irregular settlement of ground may also break underground utility lines. The upward pressure applied by the movement of liquefied soil through the crust layer can crack weak foundation slabs and enter buildings through service ducts, and may allow water to damage the building contents and electrical services. Bridges and large buildings constructed on pile foundations may lose support from the adjacent soil and buckle, or come to rest at a tilt after shaking.
Sloping ground and ground next to rivers and lakes may slide on a liquefied soil layer (termed "lateral spreading"), opening large cracks or fissures in the ground. It can cause significant damage to buildings, bridges, roads and services such as water, natural gas, sewerage, power and telecommunications installed in the affected ground. Buried tanks and manholes may float in the liquefied soil due to buoyancy. Earth embankments such as flood levees and earth dams may lose stability or collapse if the material comprising the embankment or its foundation liquefies.
In short, we may conclude that measuring water tension will give accurate data on maximum payload for the soil to settle and to prevent soil liquefaction.
In order to obtain a license for groundwater extraction on Russian territory, it is necessary to perform water level measurements - according to the Russian "Law on subsoil". One of Russia’s largest engineering companies used KELLER products to control the consumption of drinking and technical water at key railway stations.
1 - Digital indicator Evco EVК-512
2 - Output pipe
3 - Piezometric tube
4 - KELLER 26 Y level transmitter, 4…20 mA
5 - Submersible pump
Location of wells, in which KELLER transmitters have been installed
Exploration crew “Novageo” performs technological testing, geomechanical and hydrogeological well boring and monitoring of level and temperature of underground water in the open pit of the Chernogorsk deposit of non-ferrous and precious (gold, platinum) metals in the Norilsk region of Russia.
The average temperature at the Chernogorsk deposit during winter reaches -31 °С (sometimes even up to -45 °С). In the forefront of experimental filtration works and hydrological research our Client equipped 14 water wells with KELLER hydrostatic pressure (level) and temperature probes with autonomous DCX-22SG datalogger i . The probes are monitoring the level and temperature of underground water placed under perpetually frozen soil at a depth of 400-500 meters.
The probes are installed in the lower perforated end of a column of metal pipes, which have an inner diameter of 33-40 mm, with the probes' cables passing through that column. The upper part of the well with the pipe column is frozen in a permafrost interval.
After the installation of the steel columns (with water level monitoring systems installed inside) the wellheads were equipped with protective metal wellhead boxes, as well as an electrical connection to a datalogger in order to copy collected data via a K-114B cable (with option 7) interface converter.
The parameters of the sub-permafrost aquifer's water supply will be determined in accordance with the results of underground water level and temperature monitoring. These results will also help to clarify the filtration and capacitive parameters of the diastrophic block.
Open-pit mining in Chernogorsk
The mining company Rockwood Litio, operating in Salar de Atacama, located in Northern Chile, has implemented a network of DCX-22 AA CTD KELLER monitoring dataloggers into their wells, as due to environmental restrictions the level data are highly important.
Production site in Salar de Atacama
The purpose of the operation is to determine the level of groundwater and also its salt composition. This data relates directly to the operations of firstly extracting brine from the mine and then lithium from the brine.
Production site in Salar de Atacama
Due to environmental restrictions placed on mining companies by the Chilean authorities, the level data is extremely important.
The data obtained is as follows:
a) Variations in groundwater level
b) Water extracted from wells
b) Aquifer recovery following extractions.
Salar de Atacama is a hugely popular tourist attraction in Chile and therefore mining companies must exercise extreme care as excessive water extraction can lead to irreparable ecological damage.
Conductivity data is also retrieved, as it is directly related to the water’s salinity, which is in turn related to the minerals the water contains (e.g. lithium).
Production site in Salar de Atacama
Specialized KELLER titanium sensors were commissioned for this project due to the corrosive quality of the water in Salar. The AA option was chosen to deal with the extreme temperature fluctuations experienced in desert environments. High daytime temperatures and freezing night-time temperatures would eventually lead to condensation developing inside the cable if it was ventilated.
The Grib mine, located in Russia’s Mezensky District in the Arkhangelsk Oblast, is one of the largest diamond deposits in the world. During winter, temperatures can reach -25 °С (sometimes even up to -37 °С). The "Arhangelskgeolrazvedka" exploration crew conducts well boring and monitoring of underground water levels and temperature. The wells are equipped with KELLER water level monitoring systems, which allow the Client to save on special vehicles and additional staff, who would have to take readings at remote locations, which are not easily accessible.
The company conducts water level and temperature monitoring within a radius of 5 km around the deposit area. In the years 2011-2014 a total of 81 wells (with depths of 20-270 meters) have been bored in order to monitor water levels. The wells are equipped with 81 KELLER water level monitoring systems comprising of PAA-36 X W hydrostatic pressure (level) and temperature probes as well as 59 GSM-2\GSM-2 BOX modules for automatic data registration and transfer by GSM i .
The use of automatic water level monitoring systems allows to save on special-purpose vehicles and additional staff, who would conduct manual monitoring in remote and hard-to-reach wells.
Installation of level tubes at hard-to-reach locations
Installed GSM-2 box
As long as the monitoring net consists of cluster water wells, it is possible to use just one GSM-2 BOX module to register and transfer data from two to three wells placed in a distance of 5-10 meters in the same cluster. It allowed the Client to reduce the amount of GSM-2 modules required for monitoring 81 water wells from 81 to 59. Therefore the Client had to buy 22 GSM-2 modules less than anticipated, which represents approximately 15% of the price of all monitoring equipment in this project.
The Grib mine
The battery of a GSM-2\GSM-2 BOX module is able to supply several level probes. The module on the other hand can register and transfer data once a day in a low temperature environment (-25…-35 °С) with a low-level or unstable GSM-signal for a few years. During the whole exploitation period (2011-2015) the client didn’t need to change batteries in his equipment.
Extractive enterprise "Severalmaz" conducts well boring and monitoring of underground water levels and temperature in open-pit mining at the Lomonosov diamond mine in the Arkhangelsk region. The average temperature during winter can drop to -25 °С (sometimes even to -37 °С).
The Client pumps groundwater out of the open pit through several dewatering wells drilled on the perimeter. During the years 2013-2015 the 45 dewatering wells have been equipped with KELLER DCX-16VG level and temperature probes including dataloggers.
The Client chose this solution, as the product can be applied in a wet standpipe with a 20 mm (DN 17 mm) diameter 200-300 meters underground with a low error band.
Thanks to its diameter of only 16 mm, the DCX-16 level probes can be used in locations, where every milimeter counts.
KELLER Level Sensors are used to measure static and dynamic levels of water in wells in a reliable and precise manner.
Level measurement is of paramount importance as it provides information on the behaviour of the well and pumping equipment. A suitable measurement and data analysis enables proactive identification of when the well requires preventive maintenance work due to increased deterioration of the grooved well casing. The greater the incrustation, the less water can enter the well, causing water levels to fall. This results in lower electromechanical pumping efficiency, which in turn leads to higher electricity costs when pumping water from the well.
Level measurement in conjunction with the flow rate measurement also gives information on the status of the pumping equipment and the efficiency with which it is working. It is imperative to diagnose wear and tear on the pumping equipment before it fails completely. This will help avoiding major repair expenses.
It is very common that cavitation pumping equipment is not equipped for submergence and therefore lacks real time information. With a digital or analog level sensor you can program a frequency converter via a PLC to protect the pumping equipment from level changes.
It is important to install a poliduct or hose into which a sensor can be inserted to ensure correct operation and cable life longevity. Also include a desiccant dryer tube into the lifts, which measure relative pressure, to avoid moisture entering the sensors interior.
KELLER offers a wide range of level sensors with dataloggers included. This allows storage of all historical information held on the sensor and can also, over time, analyse the behaviour of the well, which assists in diagnosing any underlying issues.
Level measurement with EV06 Digital Indicator
Wells with embedded groove
Using the GSM-2, information and alerts can be relayed directly to the manager and/or operator to prevent errors in real time. The GSM-2 permits you to send data to a cell phone via SMS, e-mail or website when the information is required.
In the old days of ground water measurement, one used a conductivity switch on a measured steel or plastic flat cable, hanged in a borehole, which emitted an acoustic signal when the switch hit the water. This way the groundwater level was measured.
Nowadays these measurements can be made automatically with KELLER’s DCX22 and DCX22AA i level probes. The DCX22 (AA) are autonomous level dataloggers build up of a level sensor, a memory with microprocessor and a battery.
They are programmed in advance to perform a measurement (for example every 6 hours), store this measurement in the memory and go back into sleeping mode. The sleeping mode allows for a battery lifetime of up to 10 years. Programming and readout of the data is done via a K114A USB cable and KELLER’s logger 5.2 Windows-based software, running on a laptop or PC.
Have a look at the first graphic.
DCX22(AA) dataloggers can only measure the water column (E) above the diaphragm of the sensor. However, most geohydrologists are interested in the distance from the top of the borehole till the actual water level in the borehole. If you look at the second graphic this way of measuring becomes clear. Converting the water column to the “depth to water” is pretty simple.
One very important thing is barometric compensation. When a level sensor is placed in a fluid, it measures the fluid column + the air column, which rests on the water. If no correction is made, the measured value would not be correct as 1mbar equals 1cm of water. Thus the barometric pressure must be deducted from the hydrostatic pressure.
There are several ways to do this. The most applied method with conventional level sensors is the use of a capillar, which is a tube in the level sensor’s cable so the air pressure can “push back” on the reverse side of the diaphragm. This mechanical air pressure compensation has one risk, which is the chance of condensation in the tube, causing damage to the level sensor.
Another way is the use of a second pressure sensor to measure only the air pressure. When the signals of the level sensor and the air pressure (aka baro sensor) are deducted from each other, the pure water column remains.
The difference between the DCX22 and the DCX22AA is the integrated barometric compensation in the DCX22AA, which has a second (barometric) pressure sensor in the battery pot, which is in the head of the borehole. The DCX22AA can store both hydrostatic, barometric and the barometric compensated water levels.
The DCX22 however always needs a separate barometric data logger to collect the air pressure.
There is one condition for the use of KELLER’s DCX22AA: the barometric pressure sensor must not be flooded. Otherwise a barometric measurement cannot be made.
KELLER’s modular software allows to use both DCX22 and DCX22AA in a measuring network, as the DCX22AA’s barometric pressure can also be used to barometrically compensate the DCX22’s or a flooded DCX22AA’s hydrostatic pressure.