Changes

! Notes

! Notes

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|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.

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|Diameter||minimum 100 mm

|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.

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|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 well.  Bentonite clay is often used for this purpose.

|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.   

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|Sock||The perforated portion of the pipe should be wrapped with a geotextile sock. Standard geotextile provided with perforated pipe may be used.

|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.

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|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.

|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.

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|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.  Tops should be above the surface overflow elevation or  maximum ponding depth to prevent surface water from entering the well.  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.

|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.

|Cap||The well should be finished with a lockable cap or standard monitoring well casing and monument to protect, secure and provide access to it.

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