SR0084051 (4) - Laserfiche WebLink

Home Browse Search

SOP-009 Standard Operating Procedure Low-Flow Groundwater Quality and Sample Collection Page 6 of 9 Revision No. 1 April 2019 Sharpe Army Depot • Turn on the meter and insert the decontaminated probe from the portable water level meter through the 3/4-inch opening on the well cap. • Unlock the brake and unreel the probe and tape into the well. • Measure the water level from the north side of the casing or at the notched portion of the casing. When the buzzer sounds on the portable water-level meter, the probe has contacted water. • Confirm the reading three times by moving the measuring tape up and down. • Enter the third measurement to the nearest 0.01 foot as the pre-purge water level into sampling database. (Repeat the same procedure for the post-purge water level.) • The water level meter may be turned off or the probe moved above the water level during purging.(Following collection of the post-purge water level, remove the probe from the well.) 4.7 Well Purging The purge volume of a specific well is based on the pump’s capacity, tubing volume, and flow-cell volume. The volume of purged groundwater needs to be calculated prior to purging and sampling the well. The following describes the purging procedures: • At the well, remove the well’s sampling spigot (Teflon elbow or Tygon tubing) from the well cap and place it on the well head’s pump discharge fitting (non-mechanical, low-pressure fitting). • Select the appropriate adapter from the in-line flow cell/analyzer connector kit that will attach to the pump discharge line. • Connect the effluent end of the pump discharge adapter to the “in” port on the in-line flow cell/analyzer using the 3/8-inch Tygon tubing provided. • Attach one end of the 1/2-inch Tygon tubing to the “out” port of the in-line flow cell/analyzer and place the other end in the purge water collection bucket. • Set the pump controller to the pre-determined optimal purge settings for the well, which are noted in the well sampling database. The purge rate should not exceed 400 milliliters per minute (mL/min) (or 200 mL per 30 seconds) and should not cause a drawdown of greater than 0.3 foot. • Check the air pressure on the pressure gauge of the digital controller. Set the specific pressure on the digital controller for the well to be purged; the pressure should be set according to the information on the pump installation log sheet. The psi should be set at approximately half of the total depth for wells over 30 feet. For monitoring wells under 30 feet in length, the pressure should read about 20 psi.