Bored Wells: An Economical Water Solution

Bored Wells: An Economical Water Solution

For several years, the drilled deep well has been the basic source of supply off the mains for increased fresh water demands. As with everything else, however, inflation has taken its toll, and labor costs, taxes, and increased prices for fuel, machinery, and supplies have forced the cost of drilling up. At the same time, while the average home has a greater need for fresh water, the southeastern part of the United States, in particular, has witnessed a great growth of wholesale production of poultry and other livestock which further increased water demands in rural areas. These demands, too, are sensitive to prices.

It can be seen, then, that more and more water is needed and that costs must be kept down as much as possible. Enter the "bored well." As used in the southeastern U.S., the term means the same as augering or rotary bucket drilling in other sections of the country. A bored well is one constructed by employing a bucket or auger type rotary machine. Such wells usually are about 30 inches in diameter and cased with 24-inch i.d. concrete pipe. The equipment is high-speed, volume-production machinery capable of making one to five wells per day, depending upon formations to be bored, well depths, travel distances, and so forth. This factor has helped hold the unit cost of boring relatively low compared with other methods.

To learn more about bored wells, let's follow the construction process from rig set-up to the water tap on the pump. First, however, a site is selected by agreement between the owner and driller. Several factors must be considered, but foremost is a location least likely to be or to become contaminated from any source of pollution, be it septic tank, barnyard, or other type of agricultural or industrial waste disposal. The site also must be as convenient as possible for the owner and (of course) within reach of the boring equipment. (The north Georgia mountains can produce some challenges in this regard.)

Once the site is selected, we put the rig in place and prepare to level it and to raise the mast, or derrick. Most boring rigs are equipped with hydraulic outriggers which lift both the machinery and the truck off the ground so that the rig can be levelled precisely for the boring operation. When this is done, the mast is raised into position, also hydraulically, carrying with it the kelly bar. Today, this kelly is often of the telescoping type and quite heavy, in our area usually from 4,000 to 5,000 lbs and 75 to 100 feet long when extended in the hole. Greater depths can be reached by adding lengths of drill stem between the kelly and the bucket, but when the rig has a telescoping bar, this is a time-consuming chore. The kelly is supported by a steel cable connected to the machine draw works and is rotated by means of a large ring gear and pinion-type rotary table.

When the mast and kelly have been raised into position, and plumbed to the center of the ring gear opening, the boring bucket is attached to the kelly. This is a cylindrical device also known as an auger bucket. The entire kelly and bucket are then lowered to the surface of the ground and rotated so that the bucket teeth bite into the soil and scoop it into the bucket. (Thus the other term for this method: rotary bucket drilling.) The teeth are set in the bucket bottom at such an angle as to force the soil through slots in the bottom until the bucket is filled.