Difference between revisions of "Wells"

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File:Shallow monitoring well update.png|thumb|700px|Cross-section view of a bioretention cell with a shallow monitoring well. For further details click here for [https://sustainabletechnologies.ca/app/uploads/2016/08/LID-IM-Guide-2016-1.pdf STEP's, Low Impact Development Stormwater Management Practice Inspection and Maintenance Guide (Pg. 195 - 204).] <span style="color:red">''A note: The following is an "image map", feel free to explore the image with your cursor and click on highlighted labels that appear to take you to corresponding pages on the Wiki.''</span>
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rect 16 383 135 411 [[Geotextiles|Geotextile Sock]]
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rect 207 30 318 134 [[Wells|Lockable Cap]]
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rect 351 162 409 207 [[Wells|Lockable Cap]]
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rect 494 111 583 134 [[Wells|Lockable Cap]]
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rect 43 521 183 550 [[Digital technologies|Water Level Sensor]]
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rect 373 481 396 536 [[Digital technologies|Water Level Sensor]]
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rect 361 455 405 545 [[Wells|Solid Well Pipe]]
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rect 56 435 164 483 [[Wells|Well Casing]]
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rect 112 238 240 285 [[Flow through media|Surface Ponding]]
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rect 641 161 758 181 [[Overflow|Overflow]]
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rect 677 252 716 684 [[Pipes|Overflow Outlet Pipe]]
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rect 245 436 889 681 [[Filter Media|Filter Media]]
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rect 479 307 580 409 [[Grasses]]
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rect 245 294 889 394 [[Flow through media|Surface Ponding]]
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rect 579 216 880 396 [[Plant Lists|Vegetation]]
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This article gives tips on the design and installation of monitoring wells into LID practices. It does not address the much deeper wells used to monitor groundwater levels.  
 
This article gives tips on the design and installation of monitoring wells into LID practices. It does not address the much deeper wells used to monitor groundwater levels.  
 
Monitoring wells are frequently installed on infiltrating systems such as [[bioretention]], [[bioswales]], [[infiltration trenches]] and hybrids thereof.  
 
Monitoring wells are frequently installed on infiltrating systems such as [[bioretention]], [[bioswales]], [[infiltration trenches]] and hybrids thereof.  
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==Shallow wells==
 
==Shallow wells==
To measure the depth of ponding and the rate at which the ponding water infiltrates, install a shallow well with a water level logger:
+
For bioretention cells, stormwater tree trenches and enhanced swales featuring surface ponding areas, to measure the depth of ponding on the surface of the practice, and rate at which the ponded water drains, install a shallow well with a water level logger:
* Use a perforated pipe (a piezometer) that will allow surface water to enter the well but will help prevent sediment from accumulating within it.
+
* Use a section of perforated pipe or well screen with a geotextile sock that will allow ponded water to enter the well while preventing sediment from accumulating within it.
* Locate the well where ponding occurs first - near the [[inlet]] or the lowest point in the feature.
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* Locate the well in the deepest portion of the surface ponding area or where ponding most frequently occurs.
* Measure where the ground surface is relative to where you will be taking your water level measurements.
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* Measure the depth of the water level sensor in the well, relative to the filter media surface to translate sensor readings into surface ponding depth measurements.
* Ensure there is a small reservoir in the well to keep your level probe submerged in dry conditions. This practice will also help with calibration.
+
* Ensure there is a solid cap on the bottom of the well to provide a small water reservoir (e.g., 100 mm deep) to keep the water level sensor submerged during dry <br> conditions. This practice also helps with checking calibration of the sensor.
  
==Deeper wells==
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==Deep wells==
Some LID features which are designed to retain water during precipitation events store stored within the media that makes up the LID feature (e.g. [[permeable pavement]] will be on top of a gravel bed where water can be stored). To measure the amount of water retention in a monitoring well, install a water level logger:
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<imagemap>
* Install the well while the feature is being constructed or undergoing major maintenance.
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File:Deep monitoring well update.png|thumb|700px|Cross-section view of a partial infiltration bioretention cell with a deep monitoring well. For further details click here for [https://sustainabletechnologies.ca/app/uploads/2016/08/LID-IM-Guide-2016-1.pdf STEP's, Low Impact Development Stormwater Management Practice Inspection and Maintenance Guide (Pg. 195 - 204).] <span style="color:red">''A note: The following is an "image map", feel free to explore the image with your cursor and click on highlighted labels that appear to take you to corresponding pages on the Wiki.''</span>
* If there is an underdrain in the feature, make sure the bottom of the well reaches below it.
 
* Install the well so that surface water will not impact the water level within the well. A standard monitoring well casing over the well pipe should be sufficient.
 
* If possible, measure the depth of the underdrain. Having this measurement helps determine when water is percolating into the underdrain.
 
* Ensure there is a small reservoir in the well to keep your level probe submerged in dry conditions.
 
* Where possible, wells for measuring water levels within permeable pavement systems should be outside of trafficked areas.
 
  
===Monitoring Well Specification===
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rect 543 234 586 541 [[Pipes|Clean out / Access Pipe]]
The monitoring well should be installed during construction in a pervious area within the trench between tree planting areas. The well should be vertical from top to bottom.
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rect 573 8 756 50 [[Pipes|Clean out / Access Pipe]]
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rect 719 656 739 725 [[Digital technologies|Water Level Sensor]]
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rect 706 201 748 509 [[Wells|Solid Well Pipe]]
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rect 712 554 744 687 [[Wells|Perforated Well Pipe]]
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rect 335 61 800 235 [[Plant Lists|Vegetation]]
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rect 219 110 337 260 [[Plant Lists|Vegetation]]
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rect 541 538 590 585 [[Underdrains|Underdrain]]
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rect 219 318 792 513 [[Filter Media|Filter Media]]
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rect 218 510 791 551 [[Choker layer|Choker Layer (HPB)]]
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rect 218 554 794 689 [[Clear Stone / Internal Water Storage (IWSZ)|Bioretention: Internal water storage]]
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<br>Many types of LID practices are designed to retain water within an internal water storage reservoir or layer (e.g. full and partial infiltration [[Bioretention|bioretention]], [[Stormwater tree trench|stormwater tree trench]] and [[permeable pavements|permeable pavement]] designs, infiltration trenches and chambers, and exfiltration trenches). To facilitate measurement of water level in the internal water storage reservoir or layer and periodically evaluate drainage performance over the operating life cycle of the facility, include a monitoring well located in the lowest elevation portion of the practice or system:
 +
* Include monitoring wells in design drawings and details and install at an appropriate time during construction, or as part of repair work for facilities in need of rehabilitation.
 +
* Ensure the perforated section of the well is located within the internal water storage reservoir or layer only, and that it extends to the bottom elevation of the practice at a minimum.
 +
* Design and install the well so that surface water will not affect water level readings.  
 +
* A standard monitoring well casing and cap or monument to protect, secure and provide access to the well should also be included.
 +
* Ensure there is a solid cap on the bottom of the well to provide a small water reservoir (e.g., 100 mm deep) to keep the water level sensor submerged during dry conditions. This practice also helps with checking calibration of the sensor.
 +
* Where possible, wells should be located in areas with little or no vehicular traffic for ease of access. <br>
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</br>
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 +
==Monitoring Well Specifications==
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
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! Notes
 
! Notes
 
|-
 
|-
|Material||The pipe should be rigid to prevent bending (e.g. PVC).
+
|Pipe||Should consist of 100 to 150 mm diameter solid and perforated pipe sections joined together by threading or straight couplings. Perforated pipe section should consist of well screen pipe or smooth interior walled, rigid HDPE or PVC pipe with slot perforations along the full length.   
|Diameter||minimum 100 mm
+
|-
|Perforations||The perforations may be similar spacing similar to [[underdrain]] pipes. Perforations are only required on the bottom third of the pipe. The well should be sealed at the surface to prevent short circuiting of surface water flow along the sides of the wellBentonite clay is often used for this purpose.
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|Geotextile sock||The perforated or well screen section of the well pipe should be wrapped with a geotextile filter fabric sock to prevent sediment from accumulating in the well over time.
|Sock||The perforated portion of the pipe should be wrapped with a geotextile sock. Standard geotextile provided with perforated pipe may be used.
+
|-
|Bottom/sump||The bottom 100 mm of the well should be capped and free of perforations to provide a small reservoir of water to keep the sensor wet during dry weather.   
+
|Bottom cap||The bottom of the well should be sealed with a cap to provide a small (e.g., 100 mm deep) reservoir of water to keep the water level sensor wet during dry weather.   
|Length||The well should extend into the native soil below the facility by a minimum 150 mm. Top should be above the surface overflow elevation or above the maximum ponding depth to prevent surface water from entering the well.  If the perforated drainage pipe is installed in a v-notch below the bottom of the facility, the well should extend 150 mm below the invert of this drainage pipe.
+
|-
|Cap||The well should be finished with a lockable cap to prevent vandalism.
+
|Length||Shallow wells should extend into the filter media by a minimum of 150 mm. Deep wells should extend into the native soil below the facility by a minimum 150 mm. If the underdrain perforated pipe is installed in a shallow trench below the bottom of the facility, the well should extend 150 mm below the invert of the perforated pipe. Top elevation should be above the surface overflow outlet elevation or maximum ponding depth to prevent surface water from entering the well.
 +
|-
 +
|Top cap or monument||The well top should be finished with a lockable cap or standard monitoring well casing and monument to protect, secure and provide access to it.
 +
|-
 +
|Well casing|| For deep wells, the well casing should be sealed at the surface to prevent surface water from flowing along the sides of the well and affecting internal storage reservoir water level readings.  Bentonite clay is often used for this purpose.
 
|}
 
|}
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==External Links==
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 +
'''[https://www.toronto.ca/wp-content/uploads/2021/08/8f13-ecs-specs-gi-dwgs-T-850.041-Rev0-Sep2021.pdf Monitoring Well Standard Drawings from City of Toronto’s Green infrastructure in the Right-Of-Way]'''
 +
*Review the above technical drawings of well types used by the City of Toronto in unpaved areas, and in paved areas with both options of geotextile lined membrane and an unlined typical with a PVC slotted well.
 +
 +
*Review the below posted video showing how to install shallow and deep monitoring wells <br>
 +
:and how to effectively monitor the LID BMP practices they are used in conjunction with. <br>
 +
</br>
 +
{{#widget:YouTube|500px|id=P1JbuPlT7m4}}

Latest revision as of 18:08, 3 November 2022

Geotextile SockLockable CapLockable CapLockable CapWater Level SensorWater Level SensorSolid Well PipeWell CasingSurface PondingOverflowOverflow Outlet PipeMulchFilter MediaGrassesSurface PondingVegetation
Cross-section view of a bioretention cell with a shallow monitoring well. For further details click here for STEP's, Low Impact Development Stormwater Management Practice Inspection and Maintenance Guide (Pg. 195 - 204). A note: The following is an "image map", feel free to explore the image with your cursor and click on highlighted labels that appear to take you to corresponding pages on the Wiki.

This article gives tips on the design and installation of monitoring wells into LID practices. It does not address the much deeper wells used to monitor groundwater levels. Monitoring wells are frequently installed on infiltrating systems such as bioretention, bioswales, infiltration trenches and hybrids thereof. The two questions most frequently addressed are:

  1. How quickly is surface ponding being infiltrated beneath the surface?
  2. How quickly is the facility draining through exfiltration to native soils and/or through an underdrain?

Shallow wells[edit]

For bioretention cells, stormwater tree trenches and enhanced swales featuring surface ponding areas, to measure the depth of ponding on the surface of the practice, and rate at which the ponded water drains, install a shallow well with a water level logger:

  • Use a section of perforated pipe or well screen with a geotextile sock that will allow ponded water to enter the well while preventing sediment from accumulating within it.
  • Locate the well in the deepest portion of the surface ponding area or where ponding most frequently occurs.
  • Measure the depth of the water level sensor in the well, relative to the filter media surface to translate sensor readings into surface ponding depth measurements.
  • Ensure there is a solid cap on the bottom of the well to provide a small water reservoir (e.g., 100 mm deep) to keep the water level sensor submerged during dry
    conditions. This practice also helps with checking calibration of the sensor.

Deep wells[edit]

Clean out / Access PipeClean out / Access PipeWater Level SensorGeotextile SockGeotextile SockLocked Well CapLocked Well CapSolid Well PipePerforated Well PipeVegetationVegetationUnderdrainFilter MediaChoker Layer (HPB)Bioretention: Internal water storageMulchNative SoilNative SoilNative Soil
Cross-section view of a partial infiltration bioretention cell with a deep monitoring well. For further details click here for STEP's, Low Impact Development Stormwater Management Practice Inspection and Maintenance Guide (Pg. 195 - 204). A note: The following is an "image map", feel free to explore the image with your cursor and click on highlighted labels that appear to take you to corresponding pages on the Wiki.


Many types of LID practices are designed to retain water within an internal water storage reservoir or layer (e.g. full and partial infiltration bioretention, stormwater tree trench and permeable pavement designs, infiltration trenches and chambers, and exfiltration trenches). To facilitate measurement of water level in the internal water storage reservoir or layer and periodically evaluate drainage performance over the operating life cycle of the facility, include a monitoring well located in the lowest elevation portion of the practice or system:

  • Include monitoring wells in design drawings and details and install at an appropriate time during construction, or as part of repair work for facilities in need of rehabilitation.
  • Ensure the perforated section of the well is located within the internal water storage reservoir or layer only, and that it extends to the bottom elevation of the practice at a minimum.
  • Design and install the well so that surface water will not affect water level readings.
  • A standard monitoring well casing and cap or monument to protect, secure and provide access to the well should also be included.
  • Ensure there is a solid cap on the bottom of the well to provide a small water reservoir (e.g., 100 mm deep) to keep the water level sensor submerged during dry conditions. This practice also helps with checking calibration of the sensor.
  • Where possible, wells should be located in areas with little or no vehicular traffic for ease of access.


Monitoring Well Specifications[edit]

Feature Notes
Pipe Should consist of 100 to 150 mm diameter solid and perforated pipe sections joined together by threading or straight couplings. Perforated pipe section should consist of well screen pipe or smooth interior walled, rigid HDPE or PVC pipe with slot perforations along the full length.
Geotextile sock The perforated or well screen section of the well pipe should be wrapped with a geotextile filter fabric sock to prevent sediment from accumulating in the well over time.
Bottom cap The bottom of the well should be sealed with a cap to provide a small (e.g., 100 mm deep) reservoir of water to keep the water level sensor wet during dry weather.
Length Shallow wells should extend into the filter media by a minimum of 150 mm. Deep wells should extend into the native soil below the facility by a minimum 150 mm. If the underdrain perforated pipe is installed in a shallow trench below the bottom of the facility, the well should extend 150 mm below the invert of the perforated pipe. Top elevation should be above the surface overflow outlet elevation or maximum ponding depth to prevent surface water from entering the well.
Top cap or monument The well top should be finished with a lockable cap or standard monitoring well casing and monument to protect, secure and provide access to it.
Well casing For deep wells, the well casing should be sealed at the surface to prevent surface water from flowing along the sides of the well and affecting internal storage reservoir water level readings. Bentonite clay is often used for this purpose.

External Links[edit]

Monitoring Well Standard Drawings from City of Toronto’s Green infrastructure in the Right-Of-Way

  • Review the above technical drawings of well types used by the City of Toronto in unpaved areas, and in paved areas with both options of geotextile lined membrane and an unlined typical with a PVC slotted well.
  • Review the below posted video showing how to install shallow and deep monitoring wells
and how to effectively monitor the LID BMP practices they are used in conjunction with.