well such as intermittent pumping method, variation of the intermittent
pumping method, or surge block if it appears that the development of the
well is not producing the desired results.
3.4.2
Intermittent Pumping
**************************************************************************
NOTE: Backflow through the pump, while starting and
stopping a pump intermittently, with the check valve
removed, to produce rapid changes in the pressure
head within the well during development, called
"rawhiding," is allowed for developing extraction
and injection wells at HTRW sites. The alternate
lifting and dropping of a column of water in the
pump discharge pipe creates a surging action in the
well. For more information on this development
process, consult ASTM D 5521.
**************************************************************************
Intermittent pumping shall be performed by pumping the well at a capacity
sufficient to produce a rapid drawdown of approximately [_____] m feet
stopping the pump (backflow through pump will not be permitted) to permit
the water surface to rise to its former elevation, and repeating this
procedure. Cycle time for this procedure will vary as directed but will
not be more than 3 cycles per minute. A pump discharge in excess of
[_____] L/s gpm will be required. A deep well turbine pump, or electric
submersible pump with check valve, shall be used with any attachment
necessary to accomplish rapid starting and stopping for intermittent
pumping. The intake shall be set at least 3 m 10 feet below the maximum
expected drawdown in the well. Prior to commencing intermittent pumping,
and periodically during development by this method, all sand and/or other
materials shall be removed from inside the screen. The amount of drawdown
may be decreased if, in the opinion of the Contracting Officer, the
efficiency of the well might otherwise be impaired.
3.4.3
Surging
Surging of the well shall require use of a circular block, or multiple
blocks, which are approximately 25 mm 1 inch smaller in diameter than the
inside diameter of the well and is constructed of a material which will not
damage the screen if the block comes in contact with the screen, and a
bailer or pump to remove materials drawn into the well. The surging shall
be continued for a period of approximately [one][____] hour, or until
little or no additional material from the foundation or filter pack can be
pulled through the screen. The surge block shall be moved by a steady
motion up and down the full length of the well screen. Prior to commencing
surging, and periodically during development by this method, all sand
and/or other materials shall be removed from inside the screen. All
materials pulled into the well by the surging process shall be removed by
the Contractor.
3.4.4
Well Development Criteria
**************************************************************************
NOTE:
The U.S. Environmental Protection Agency
(EPA) may, according to their Technical Enforcement
Guidance Document (TEGD), 530/R-93/001, consider a
well installed at an HTRW site improperly completed
if a well yields turbid samples (turbidity greater
SECTION 02521
Page 29
Previous Page
