What are the methods used to make well and bore well?

Creating a well involves several distinct methods, each suited to different geological conditions and water depth requirements. According to common classifications, wells are primarily made using three distinct methods: dug/bored wells, driven wells, and drilled wells. Each method utilizes different tools and techniques to access underground water sources.

Methods Used to Make Wells and Bore Wells

Understanding the construction methods of wells is crucial for effective water sourcing and management. The chosen method depends on factors such as the water table's depth, soil type, and required yield.

1. Dug/Bored Wells

Dug/bored wells are among the oldest and simplest forms of well construction. They are typically shallow and wide, accessing water from the uppermost aquifers.

• Methodology: These wells are created by manually digging a hole in the ground.
• Tools Used: Common tools for this process include:
  • Shovels: For manual excavation.
  • Backhoes: For more extensive or less labor-intensive digging.
• Characteristics:
  • Generally shallower, often not exceeding 50 feet in depth.
  • Wider diameter, allowing for manual entry for maintenance or cleaning.
  • Historically, they were lined with stones, bricks, or concrete rings to prevent collapse.
  • More susceptible to surface contamination if not properly sealed and maintained.

2. Driven Wells

Driven wells offer a relatively quick and economical method for obtaining water, particularly in areas with shallow water tables and soft, permeable soils like sand or gravel.

• Methodology: This type of well is made by driving a pipe directly into the ground. A well point (a screened pipe section with a drive shoe) is attached to the bottom of the casing pipe and hammered into the earth.
• Tools Used:
  • Well point: A screened pipe section at the bottom.
  • Casing pipe: The main pipe driven into the ground.
  • Driving equipment: Such as sledgehammers or specialized mechanical drivers.
• Characteristics:
  • Typically shallow, usually less than 50 feet deep.
  • Small diameter, generally 1.25 to 2 inches.
  • Suitable for loose soils where there are no significant rock layers.
  • Less prone to surface contamination than dug wells due to their sealed nature.

3. Drilled Wells

Drilled wells are the most common type of well for residential and public water supplies today. They can reach significant depths, accessing deeper, more reliable aquifers, and are capable of penetrating various geological formations, including solid rock.

• Methodology: These wells are created using powerful mechanical drilling equipment.
• Tools Used: There are two primary types of drilling machines:
  • Percussion-drilling machines: These machines operate by lifting and dropping a heavy drilling bit to crush and break up rock and soil. The broken material is then bailed out. This method is effective in hard rock formations.
  • Rotary-drilling machines: These machines use a rotating drill bit to cut through the earth and rock. Drilling fluid (mud) is circulated down the drill pipe to cool the bit, carry cuttings to the surface, and stabilize the borehole. Rotary drilling is fast and efficient across various geological conditions.
• Characteristics:
  • Can range from 100 feet to over 1,000 feet in depth.
  • Diameters vary but are typically 4 to 12 inches.
  • Highly reliable for consistent water supply.
  • Generally the most expensive method but offer superior water quality and quantity.
  • Require casing and often a grout seal to prevent contamination from shallower water zones.

Comparison of Well Construction Methods

Each method offers distinct advantages and disadvantages, making the choice dependent on specific site conditions and water needs.