Types of Protective Casings used for Monitoring Wells

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Types of Protective Casings used for Monitoring Wells

Monitoring well

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Protective casings for monitoring wells, also known as surface completions, ensure the integrity of the well by preventing physical damage and unauthorized access.

Types of Protective Casings

  • Above-Ground (Stick-Up) Casings: These consist of a steel pipe (round or square) installed over the well casing and extending approximately 2 to 3 feet above the ground. They typically feature a lockable, hinged, or weather-tight cap to prevent tampering and rain intrusion.
  • Flush-Mount Casings (Manholes): Used in high-traffic areas (e.g., roads, parking lots) where an above-ground extension is impractical. These consist of a heavy-duty cast iron or composite cover set flush with the ground inside a protective skirt.
  • Steel Bollards: While not a casing itself, three 5-inch diameter steel posts are often installed around a stick-up well for additional impact protection.
  • Well Seals and Caps: These provide a secondary layer of protection by sealing the internal PVC casing directly with a watertight or vermin-proof lid.


1. Above-Ground (Stick-Up) Protective Casing

Standard installations for non-traffic areas require a durable steel outer shell to prevent physical damage and tampering. 

  • Dimensions: The protective steel casing should be approximately 1.5 metres (5 feet) in total length, with about 0.75 metres (2.5 feet) installed below the ground surface into the borehole.
  • Casing Height: The top must extend at least 40 cm (16 inches) above the highest point of the ground surface within a 3-metre radius.
  • Material: Typically 141 mm (approx. 5.5 inches) diameter steel pipe with a lockable cover.
  • Surface Completion: A concrete pad or surface mound (compacted soil, clay, or bentonite) must be constructed around the casing to direct surface water away from the well.
  • Venting: A small vent hole or slot should be cut below the bottom of the internal PVC cap to allow for air movement and proper water level fluctuation. 

2. Flush-Mount (Manhole) Protective Casing 

Required in high-traffic areas like parking lots or roads where an above-ground extension would be a hazard. 

  • Construction: Consists of a watertight, commercially manufactured cover set flush with the ground.
  • Vault Requirements: If a well pit (vault) is used, the top of the internal well casing must still be at least 40 cm (16 inches) above the floor of the pit to prevent internal flooding from impacting the well.
  • Load Rating: For vehicular areas, casings must meet H-20 traffic loading standards to support the weight of heavy trucks. 

3. Internal Well Casing (Riser) Specs

  • Diameter: Standard permanent wells typically use a minimum 50 mm (2-inch) ID casing, though 1-inch “microwells” are used for specific direct-push applications.
  • Materials: Most commonly Schedule 40 PVC with threaded, watertight joints. No glues or solvents are permitted as they contaminate water samples.
  • Annular Space: The borehole must be at least 102 mm (4 inches) larger than the outside diameter of the casing to allow for proper filter pack and seal placement (e.g., a 2-inch casing requires a 6-inch borehole). 
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