METHODS

 

Once a week, I checked three well nests on UVM's main campus for top-of-casing water levels, temperature, and conductivity. The procedure at each well nest was the same week to week. Top-of-casing water levels were taken first, followed by temperature, and conductivity.

Using a well key, I removed the protective well cover and lowered the depth meter above the previous week's water level. The water level is located when the meter sounds. I would raise the depth meter above the water level and wait for sounding to stop. While holding my thumb and index finger directly on the casing top, I lowered the meter until reaching the air/water interface. This was repeated until knowing the exact distance between the air/water interface and the casing top. The depth meter was graduated intermittently, therefore, I used a tape measure to record exact distance. I would then record the measurement on a form-organized spreadsheet.

Temperature and conductivity were taken with a VSI-3000 T-L-C meter. Since the depth of the air/water interface is known, the temperature/conductivity meter was always lowed three feet below the interface to ensure consistency. I would turn the temperature meter on, lower it to position, and let the indicator settle to record degrees Celsius. With the meter still in position, I would turn on conductivity to the most sensitive level. If the reading exceeded the sensitivity, I would turn the meter to a coarser setting. Again, I let the reading settle and recorded the measurement. The meter was then rinsed with deionized water. This ensures there will be no future well contamination and zeros the conductivity meter. The well cover was then replaced and secured.

On a monthly basis, I performed a well sampling procedure. Before the sample was taken I would record water level, temperature and conductivity in the same manner as above. To ensure a true sample of ground water, each well must be bailed at least three well volumes or until dry. I calculated the well volume by multiplying the basal area (3.14 x radius squared=20.26 cm squared) by the length of the water column. This well volume multiplied by three is the minimum amount of bailed water to ensure a true ground water sample(click here for graph). As water was bailed from the well, I would pour it into a graduated bucket to measure the volume collected. After the bailing procedure was completed, I collected the water in a clean sample jar, capped it, and waited for the particulate matter to settle. Using a syringe, I extracted water from the surface of the sample jar. I used a 0.45 micrometer filter to dispense the sample into a sterile, properly labeled test tube. For each well, I gathered one cation sample and one anion sample. After bailing I would measure and record the well temperature and conductivity. Once back at the laboratory I would introduce approximately five drops of 30% HNO3 to the cation sample to keep dissolved metals in solution. Samples were then analyzed by either Jen Larson or Adam Walker, lab technicians at the University's Plant and Soil Laboratory (anion procedure) (cation procedure). Bailers were cleaned with deionized water and wrap with tinfoil to await the next sampling day.

Taking a sample from ground water well #2 in mid-July 1999

Continuous water measurements were recorded in ground water wells 2 and 3 with the Hermit 1000B data logger. This device recorded measurements every hour and was downloaded every week. Click here for downloading instructions.