Groundwater filters through soil and rocks to pool in underground rock basins, also known as aquifers. Pesticides, fertilizers, and other contaminants also filter down into aquifers. Sometimes groundwater is not drinkable because of outside contamination, but it can also be contaminated by naturally occurring minerals in the rock formation, such as lead and arsenic, which are filtered out as the water travels through them. Special geologic maps, available from the United States Geologic Survey (USGS), provide the depths of groundwater. To determine the depth of groundwater accurately for yourself, you need to have access to several groundwater monitoring wells and a water level meter/indicator. Does this Spark an idea?
Instructions
Depth to Groundwater
1. To locate groundwater, you can use landscape cues. Shallow groundwater usually occurs under verdant valleys across climates. Cottonwood and willow trees indicate the presence of shallow groundwater in dry desert climates. Springs, seeps, swamps, and lakes all indicate shallow to moderately deep groundwater but do not indicate quantity.
2. To determine groundwater depth accurately, you need to have access to several groundwater monitoring wells spread out over the area to be measured. When wells are drilled, a record is made of the type of rock encountered, the water quality, and the depth to the groundwater. Ground elevation is recorded from the north side top of the PVC casing of each well to ensure consistency between sampling events. Note those figures, then lower a water level meter with a cable measuring tape into a well. Once the meter encounters water, a light or buzzer indicator will go off.
3. Water meters can be obtained from engineering supply facilities, but you can also use a long measuring tape marked off with chalk. Lower the tape deep into the well. When you believe you have encountered water, record the measurement, pull the tape up, and subtract the wet length of of the tape to determine the actual water depth. Read and record that measurement. Then repeat the procedure for each well in the area.
4. All sampling equipment has to be decontaminated to reduce cross contamination or transfer of contaminants to clean areas. The process is designed to remove particles, trace metals, and organic chemicals. A series of washes with different detergents and agents will meet these objectives. First, wash sampling equipment with non-phosphate detergent. Then steam and use high-pressure water to remove particles. Rinse equipment with tap water and distilled/deionized water to get rid of detergents. To remove trace metals, rinse with a 10 percent nitric acid wash and another distilled/deionized water rinse. To get rid of trace organic chemicals, use a high purity solvent-like acetone. Let the solvent evaporate completely and then use a final distilled/deionized water rinse.
5. Once you have obtained the figures, subtract the depth to groundwater from the ground elevation to determine the elevation of the water table. Place this information on a map showing each well. Connect the wells and draw in contour lines at 5 foot intervals to represent the groundwater level over the entire measured area.
6. Contour maps use lines to connect points of equal elevation or depth. Contours show the shape of a surface, most often land surfaces, but can also be used to show the shape of groundwater depth or bathymetric surfaces. Contour lines are drawn in the same way you would connect the dots of a picture, except you only connect points of equal elevation or depth to make concentric circular shapes. For groundwater, each line would be marked for specific depth below ground surface.
Tags: deionized water, depth groundwater, distilled deionized, distilled deionized water, each well, access several
