The Reston Groundwater Dating Laboratory
Information Useful in Age Determination
Well Construction Data
- Depth, elevation, construction (open hole, perforations,
etc), depth below water table, length of screened interval,
pump depth, casing material, etc.
- Oxygen, specific conductance, temperature, hydrogen
- Pump type, discharge tubing (copper, Nylon, etc.)
- Bubbles in discharge, particulates in water, cloudy
water, raw or finished sample, etc.
- Recharge or discharge area, confined or unconfined formation,
fractured rock, karst, sand and gravel, etc.
- o2, h2s, ch4, excess
n2, low ar and n2-degassing
- tritium, 3h-3he, sf6,
- Background constant (oxygen present) or very variable
- Compare duplicate chromatograms (trends in concentration , random variation in
concentration, etc. indicating draw-down or not purged
- N2O present? Nitrate reducing (fertilizers,
- H2S present? Sulfate reducing
- Other contaminants (halocarbons) present? Are the CFC's
- Degradation of contaminants?