SISGEO manufactures a range for piezometers for various applications. Broadly speaking, a piezometer measures water levels or water pressures within a borehole or in the ground. There are various methods of doing this, ranging from a simple tube set at depth in a gravel filter zone, from which a water level reading is taken, to more sophisticated instruments which measure pore water pressures.
Standpipe piezometers are used to monitor piezometric water levels.
Observation wells are used to monitor ground water levels. Typical applications include:
• Monitoring pore-water pressure to determine the stability of slopes, embankments, and landfill dikes.
• Monitoring the effectiveness of dewatering schemes.
• Monitoring seepage and ground water movements in embankments, landfill dikes, and dams.
CASAGRANDE AND STANDPIPE PIEZOMETERS
The standpipe piezometer, alternatively known as a Casagrande piezometer, comprises a filter tip joined to a riser pipe. The filters are made from high density polyethylene with a threaded cap joint for a standpipe arrangement of two ‘half inch’ tubes or one ‘1 inch’ tube. The riser pipe is typically made from PVC plastic pipe. After the filter tip and standpipe are installed in the hole, a sand filter zone is tremied into place around the filter tip, following which the top of the filter zone is sealed with a bentonite plug which isolates the filter zone. The annular space between the standpipe and the borehole is backfilled to the surface with a bentonite grout to prevent vertical migration of water. The standpipe is terminated above ground level with a vented cap and protective cover. If the soil is very soft, standpipe piezometers can be pushed into position using a steel well point with an integral filter tip.
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WATER LEVEL INDICATORS (WLI) [Dipmeters]
Dipmeters (WLI) are used for ground water level measurements in standpipes, wells and Casagrande
piezometers. The dipmeter is a battery powered portable device equipped with a dipping probe connected to a graduated cable wrapped on a cable reel. When the dipping probe comes into contact with water, it activates either an audible alarm and a light indicator mounted on a reel faceplate. The C112T version is also equipped with a dipping probe for temperature measurements. A LCD on the reel faceplate displays the temperature value directly in ˚C.
Technical Specifications
| MODEL C112 | class II flat cable with markings every millimetre |
| Probe | water level detector |
| Available cable lengths | 30, 50, 100, 150, 200, 300, 400, 500 m |
| MODEL C112T | class II flat cable with markings every millimetre |
| Probe | water level detector and temperature sensor |
| Available cable lengths | 30, 50, 100, 150, 200, 300, 400, 500 m |
| Reel diameter | 260 mm, 320 mm, 420 mm |
| Probe diameter | 10 mm |
| Display | 3.5 LCD (only for C112T) |
| Battery | 9V DC disposable |
STAFF GAUGES
(Product code 0HIDR100000)
Staff gauges are used for direct readings of water level in reservoirs, rivers and open channels. They consist of 1 m long porcelain enameled hydrometric rod with centimetre graduation and reference plate.
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WATER LEVEL LOGGER (WLL)
Water Level Logger (WLL) is an integrated system designed for automatic continuous monitoring of water level and temperature inside wells, standpipes and Casagrande piezometers. WLL system is equipped with an accurate ceramic pressure sensor which provides high accuracy and long-term stability measurements. The Water Level Logger records absolute pressure, which is later converted to water level readings by the Hoboware software using barometric measurements. The optical USB connection interface provide safe and reliable data download also in bad environmental conditions.
Technical Specifications
| Water level range* | 9, 30, 76 m |
| Temp. range | -20°C +50°C |
| Accuracy | |
| - water level* | ±0.05% F.S. |
| - temperature | ±0.5°C |
| Memory type | Non-volatile |
| Memory capacity | 64k-byte >21.000 combined measurements |
| Measuring Interval | Programmable min 1 sec, max 18 hours |
| Communication port | Optical USB interface |
| Temp.operating range | -20°C +60°C |
| Battery life*** | 5 years typical with min. measuring interval 1 min |
* nominal value based on using WLL at sea level
** typical error using reference level measurement and the barometric compensation
*** depending also from working temperature
HOBOWARE MANAGER SOFTWARE
(Product code 0WSBHW10000)
This software is the next generation software for logger management, data graphing and data analysis; it permits to check the logger status: verify logger set-up before launch, verify logger operation while logging, display real-time sensor readings and display memory used and battery voltage. Software’s powerful graphing features let you plot and filter data for a customized data presentation. Barometric compensation assistant allows for compensation of water level measurements for barometric pressure.
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ELECTRICAL PRESSURE TRANSDUCERS
A wide range of electrical piezometers and pressure transducers are available for different applications. Electrical piezometers and pressure transducers are equipped with a deformable diaphragm with screen printed resistor gauges forming a 4-arms Wheatstone bridge. The P235S piezometers are used to monitor pore pressure when a fast response, dynamic measurements and/or high accuracy are required. The model P252A is supplied with a 1/2-inch male thread to be coupled with a hydraulic pressure line (for up-lift water pressure monitoring).
Technical Specifications
| MODEL P235S1 | with HAE value filter |
| MODEL P235S4 | with LAE value filter |
| MODEL P235I | Drive-in version to be pushed into a soft soil |
| Standard ranges | 100, 200, 500 kPa |
| 1, 2, 5, 10, 20 MPa | |
| Sensitivity | 0.01% FS |
| Accuracy | < 0.3% FS |
| Temp. Operating range | -10°C +55°C |
| Filter unit characteristic | |
| - HAE (100 kPa) | 1 µ ceramic stone |
| - LAE stone | 40 µ sintered s/steel |
| 40/50 µ syntherized PE | |
| Diameter / length | 27 mm / 200 mm |
VENTED PRESSURE TRANSDUCER
The P252R pressure transducer is equipped with a vented sensor, which provides automatic compensation for barometric pressure changes. This transducer provides ground water table monitoring in Casagrande piezometers, wells and standpipe piezometers.
REMOVABLE PORE PRESSURE TRANSDUCER
P252C is a removable pressure transducer for soil pore pressure monitoring. It is suitable for long-term monitoring, as the instrument can be removed for calibration checks, maintenance or re-used in other boreholes. When inserted into the P101 filter unit, the pressure seal is assured by its conical tip with an O Ring kept in place on the cable by a string of dead weights.
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FLOW METERS
Water flow monitoring in open channels is widely employed in the environmental and geotechnical fields. Leakage measurement is one of the most important indicators of the overall performance of earth/rock-fill and concrete dams. The leakage rate is a function of the water level in the reservoir and depends either on the construction and/or the integrity of the dam.
Consequently, leakage monitoring provides data for the evaluation of the long-term stability of the dam structure.
Leakage water is usually impounded downstream from the dam and diverted to a basin in a weir station.
Technical Specifications
V Notch Weirs
The purpose of the weir is to transform the instantaneous flow values into the pressure/level by means of specific measuring equipment.
| 0QV45LS1000 | 10 litre/sec. V-angle 45 Degrees |
| 0QV60LS2000 | 20 litre/sec. V-angle 60 Degrees |
| 0QV90LS5000 | 50 litre/sec. V-angle 90 Degrees |
Measuring Equipment
QVLIV100 Level Transducer
Product Code 0QVLIV10000
| Transducer Type | floating unit with high sensitivity load cell |
| Measuring Range | 1000 mm of water level variation |
| Sensor resolution | 1mm |
| Accuracy | > 0.3 % FS |
| Output Signal | 4-20 mA (current loop) |
P25 1Q100 Level Transducer
(Product Code 0P251Q10000)
| Transducer Type | Pressure transmitter |
| Measuring Range | 1000 mm variation in water level |
| Accuracy | >0.5 % FS |
| Output Signal | 4-20 mA (current loop) |
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VIBRATING WIRE PIEZOMETERS
Vibrating Wire piezometers are strongly recommended for long term monitoring of soil pore pressure or groundwater levels. The VW piezometer consists of a stainless steel body equipped with a filter unit (porous stone) and a pressure sensitive diaphragm with tensioned steel wire. The vibrating wire is tensioned inside a hermetically sealed and evacuated space. VW piezometers guarantee fast response, long-term stability and immunity to voltage surges (lightning). Readings of VW piezometers are obtained by vibrating wire readout or datalogger. Filter units are available with different porosity: either HAE (high air entry) or LAE (low air entry) value filters are suitable for piezometer applications in impervious, saturated and permeable soils.
Technical Specifications
| MODEL PK45A | with HAE value filter unit |
| MODEL PK45S | with LAE value filter unit |
| MODEL PK45I | drive-in version to be pushed into a soft soil by push-in rods |
| Standard ranges | 200, 350, 500, 700 kPa |
| 1.0, 1.7, 2.0, 3.5 MPa | |
| Sensitivity | ± 0.025% FS |
| Accuracy | < 0.5% FS |
| Temp. operating range | -20°C +100°C |
| Filter unit features | |
| - HAE (100 kPa) | 1 µ ceramic stone |
| - LAE stone | 40 µ sintered s/steel |
| 40/50 µ sintered PE | |
| Diameter / length | 27 mm / 200 mm |
SATURATION DEVICE
(Product code 0PF01SAT000)
The filter saturation is a decisive factor of a successful installation of embedded piezometers. Sisgeo provides a device for field use for the saturation of the HAE value filter (ceramic stone). It consists of a stainless steel pump with manometer and a threaded port to fit the filter unit.
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