|
Section 10. Surface Construction Features.
Surface construction features of a monitoring well shall serve to prevent
physical damage to the well; prevent entrance of surface water, pollutants,
and contaminants; and prevent unauthorized access.
- Locking Cover. The top of a monitoring well shall be protected by a
locking cover or equivalent level of protection to prevent unauthorized
access.
- Casing Cap. The top of a monitoring well casing shall be fitted with a
cap or "sanitary seal" to prevent surface water, pollutants, or contaminants
from entering the well bore. Openings or passages for water level
measurement, venting, pump power cables, discharge tubing, and other access
shall be protected against entry of surface water, pollutants, and
contaminants.
- Flooding. The top of the well casing shall terminate above ground
surface and known levels of flooding, except where site conditions, such as
vehicular traffic, will not allow.
- Bases. Unless otherwise approved by the enforcing agency, a concrete
base or pad shall be constructed around the top of a monitoring well casing
at ground surface and contact the annular seal, unless the top of the casing
is below ground surface as provided by Subsection E, below. The base shall
be at least 4 inches thick and shall slope to drain away from the well
casing. The base shall extend at least two feet laterally in all directions
from the outside of the well boring, unless otherwise approved by the
enforcing agency.
The base shall be free of cracks, voids, and other significant defects likely
to prevent water tightness. Contacts between the base and the annular seal,
and the base and the well casing must be water tight and must not cause the
failure of the well casing or annular seal.
Where cement-based annular sealing material is used, the concrete base shall
be poured before the annular seal has set, unless otherwise approved by the
enforcing agency.
- Vaults. At the approval of the enforcing agency, the top of the well
casing may be below ground surface because of traffic or other critical
considerations. A structurally-sound watertight vault, or equivalent
feature, shall be installed to house the top of a monitoring well that is
below ground surface. The vault shall extend from the top of the annular
seal to at least ground surface. In no case shall the top of the annular
seal be more than 4 feet below ground surface.
The vault shall contact the annular seal in a manner to form a watertight and
structurally sound connection. Contacts between the vault and the annular
seal, and the vault and the well casing, if any, shall not fail or cause the
failure of the well casing or annular seal.
Where cement-based annular seal materials are used, the vault shall be set
into or contact the annular seal material before it sets, unless otherwise
approved by the enforcing agency. If bentonite-based sealing material is
used for the annular seal, the vault should be set into the bentonite before
it is fully hydrated.
Cement-based sealing material shall be placed between the outer walls of the
vault and the excavation into which it is placed to form a proper,
structurally sound foundation for the vault, and to seal the space between
the vault and excavation. Bentonite-based sealing material may be used
between the vault and excavation at the approval of the enforcing agency.
Sealing material surrounding a vault shall extend from the top of the annular
seal to ground surface, unless precluded in areas of freezing. If cement-based sealing material is used for both the annular seal and the space
between the excavation and vault, the sealing material shall be placed in a
"continuous pour." In other words, cement-based sealing material shall be
placed between the vault and excavation and contact the cement-based annular
seal before the annular seal has set.
The vault cover or lid shall be watertight but shall allow the venting of
gases, unless otherwise approved by the enforcing agency. The lid shall be
fitted with a security device to prevent unauthorized access. The lid shall
be strong enough to support vehicular traffic where such traffic might occur.
The top of the vault shall be set at or above grade so drainage is away from
the vault. The top of the well casing contained within the vault shall be
covered in accordance with requirements under Subsections A and B, above, so
that water, contaminants, or pollutants that may enter the vault will not
enter the well casing.
- Protection From Vehicles. Protective steel posts, or the equivalent,
shall be installed around a monitoring well casing where it is terminated
above ground surface in areas of vehicular traffic. The posts shall be
easily seen and shall protect the well from vehicular impact.
Additional requirements for surface construction features are in Section 10
of the Water Well Standards.
|
