1. Subsurface study of a small valley aquifer in central New York has revealed the following information:

The saturated thickness of the aquifer is 50 feet.

The transmissivity of the aquifer is 500 ft²/day

The horizontal dimension of the aquifer averages 1000 feet

The gradient on the potential surface is 10 feet per 1000 feet

Using Darcy’s Law, calculate the discharge through the aquifer in ft³/day.

2. The effective porosity of the aquifer material in the case above is 0.20. Calculate the seepage velocity of water in the aquifer.

3. The aquifer described above is bounded at its base by nearly impermeable shale bedrock. A train has jumped the tracks and the tank cars carrying gasoline, lubricating oil and chlorinated hydrocarbons used in the dry-cleaning industry have ruptured and spilled their contents. Sketch a cross-section of the aquifer parallel to the groundwater flow direction and illustrate and explain where you would expect to find contamination by these materials, and which will form LNAPL, DNAPL and APL components in the system.

4. The map below shows the distribution of water table elevations in the vicinity of a small stream and pond. Are the stream and pond gaining (receiving water from the groundwater system) or losing (adding water to the groundwater system? Draw isopotential lines and flowlines which illustrate the system.

5. The drawdown curves below were derived from pump tests of two different aquifers. The test conditions (saturated thickness of the aquifers, discharge from the pumping well, distance from the pumping well to the monitor well) are the same for both aquifers. Which of the aquifers would make a better water supply? Why?

6. Your local health club has a water supply well which has become contaminated by leachate from a pile of rock salt (halite) used for road de-icing. The owners of the rock salt pile have agreed to pay for the installation of a water-softening system to take care of the problem. What dissolved ions are likely causing the contamination problem? What are the health risks associated with this contamination? Will a water-softening system take care of the problem? Why or why not?

7. Why might low pH groundwater pose a moderate health risk in a domestic water supply system? What are the specific contaminants that you would test for to identify a health risk?

1. How do we calculate groundwater flow velocity using Darcy’s Law?

2. How are aquifer boundaries (recharge or impermeable boundaries, for example) reflected in time-drawdown curves?

3. How do the rock and mineral compositions of aquifer materials control groundwater quality?

4. Describe the relationship between nitrate pollution of groundwater, recharge and aquifer oxygenation.

5. How do viscosity, volatility and solubility in water vary among the various members of the aromatics and alkanes?

6. What factors control the effectiveness of biodegradation of petroleum hydrocarbons in the subsurface?

7. What factors control the range and variation of hydrogen and oxygen stable isotopes in meteoric waters? How does the ‘meteoric water line’ help explain this variation?

Part II (you got this map as a handout in class recently)

The map depicts the distribution of groundwater wells in an area of phenol contamination from an old tannery site in the southern Adirondacks. Note that Cedar Creek flows from NE to SW through the area. The hydrogeology is straightforward – bedrock consists of low conductivity granitic gneiss; outwash is high conductivity gravel and sand. In general, the wells in the area are 10-20 meters in depth and the water table is typically encountered 3-5 meters below the surface. Phenolic compounds are a by-product of the tanning operation, and for years waste liquids were dumped on the soil in the area indicated ‘tannery’. Phenols are relatively long-lived, slightly soluble materials that will travel with groundwater, impart an unpleasant odor and taste to drinking water, and are considered carcinogenic. In this case, phenol contamination was detected in five wells in the area, and the residents who own the wells are preparing to sue the present tannery property owner for damages.

Your task is to assess the groundwater flow paths and relationship of pollutant source to well contamination. The best way to proceed is to prepare a flow net of the area using the water table, stream surface and pond elevations. Use water table contours, flowlines, and well data to broadly define the flow path of contamination. Then answer the questions below.

1. Generally describe the groundwater flow pattern in the area.

2. In the area of the three gaging stations, is Cedar Creek a gaining or losing stream? Explain how you know.

3. Are all the wells exhibiting phenol contamination equally likely to have the tannery property as the contaminant source? Explain.