comprehensive site investigation and remediation objectives report

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LOW-FLOW GROUNDWATER SAMPLING PROTOCOLS
A static water level measurement will be taken prior to commencing any purging and
sampling activities. The groundwater level will be measured using an electric water level
indicator. The depth to water will be measured from a datum marked on the rim of the
riser pipe to an accuracy of +0.01 feet. The static water level measurements will be
recorded in the field logbook.
A micro-purge low-flow method will be used for well purging prior to sampling. This
method is used to provide for representative samples while minimizing purge water and
minimizing disturbance of sediment in the well that may be caused by over-pumping.
The procedure to be used is as follows:
• Prevent decontaminated equipment from contacting the ground surface by using
new plastic sheeting or by placing tubing/pumps in clean storage tubs.
• Slowly lower the decontaminated pump into the well until the pump intake is in
the middle of the screen interval. Measurement of the water level in the well is
needed prior to well purging. The pump tubing will be clearly marked with depth
increments to facilitate accurate determinations of pump depth.
• Secure the tubing to the wellhead when the pump is at the desired depth.
• The dedicated polyethylene lined tubing will be secured so purging will take place
from the approximate midpoint of the monitoring well screen.
• Turn pump on and slowly increase to a flow rate of 100 ml to 500 ml per minute,
and discharge directly into bucket until turbidity has decreased. Check water
level periodically to monitor drawdown in the well as a guide to flow rate
adjustment. The goal is minimal drawdown (