Current through Register Vol. 48, No. 38, September 20, 2024
a) At a minimum, all monitoring well
construction must satisfy the following requirements:
1) Wells must be constructed in a manner that
will enable the collection of representative groundwater samples;
2) Wells must be cased in a manner that
maintains the integrity of the borehole. Casing material must be inert so as
not to affect the water sample. Casing requiring solvent-cement type couplings
must not be used;
3) Wells must be
screened to allow sampling only at the desired interval. Annular space between
the borehole wall and well screen section must be packed with clean,
well-rounded and uniform material sized to avoid clogging by the material in
the zone being monitored. The slot size of the screen must be designed to
minimize clogging. Screens must be fabricated from material that is inert with
respect to the constituents of the groundwater to be sampled;
4) Annular space above the well screen
section must be sealed with a relatively impermeable, expandable material such
as cement/bentonite grout that does not react with or in any way affect the
sample, in order to prevent contamination of groundwater samples and
groundwater and avoid interconnections. The seal must extend to the highest
known seasonal groundwater level;
5) The annular space must be backfilled with
expanding cement grout from an elevation below the frost line and mounded above
the surface and sloped away from the casing so as to divert surface water
away;
6) Wells must be covered with
vented caps and equipped with devices to protect against tampering and damage.
Locations of wells must be clearly marked and protected against damage from
vehicular traffic or other activities associated with expected site use;
and
7) Wells must be developed to
allow free entry of groundwater, minimize turbidity of the sample, and minimize
clogging.
b) Monitoring
well construction diagrams must be completed for each monitoring well. The well
construction diagrams must be submitted in the corresponding site investigation
plan, site investigation completion report, or corrective action completion
report on forms prescribed and provided by the Agency and, if specified by the
Agency in writing, in an electronic format.
c) Static groundwater elevations in each well
must be determined and recorded following well construction and prior to each
sample collection to determine the gradient of the groundwater table, and must
be reported in the corresponding site investigation plan, site investigation
completion report or corrective action completion report.
