b. Sanitary Protection of Wells.
(1) Location. The location of a well is one of the most important
considerations in ensuring its sanitary quality. A location should always be selected
which wiII prevent, as nearly as possible, contamination by percolation through the soiI.
Water or wastewater wiII generally percolate vertically through the soiI untiI it reaches
the water table. When it reaches the water table, it wiII follow the general direction of
flow of the underground water. This flow normally approximates the contours of the
earth's surface, but not necessariIy. Wherever possible, a well should be located uphiIl
from a possible source of contamination; however, this is not positive assurance that the
point at which the well draws water from the water table is not below the level at which
contamination may be carried by percolation into the water table. In order to minimize
this possibiIity, wells should be located at least the following distances from sources of
(a) Building sewer--100 feet.
(b) Septic tank--100 yards.
Sewage disposal field--100 yards.
(d) Seepage pit--100 yards.
(e) Dry well--should be sealed.
Where there is good reason to believe that the soiI is quite permeable, such
as a Iimestone formation, these distances should be increased.
(a) The annular space between the well casing and the surrounding
soil formation should be filled with watertight cement grout from the surface to a depth
of at least 10 feet.
(b) The casing should be surrounded by a 4-inch concrete slab
extending at least 2 feet in all directions and sloping away from the casing.
(c) A sanitary well seal should be installed at the top of the well casing
to prevent the entrance of contaminated water or other objectionable material.
(d) For artesian aquifers, the casing should be sealed into the overlying
impermeable formation so as to retain the artesian pressure.