Geo 105

Which of the following are part of a typical groundwater contamination investigation?

*Collection of geochemical samples *Testing of the aquifer *Comparison of sample results to federal standards

which of the following are part of a typical groundwater contamination investigation?

*Comparison of sample results to federal standards *Testing of the aquifer *Collection of geochemical samples

Which of the following are human-made or human-induced substances that can contaminate groundwater?

*Human wastes *Herbicides *Insecticides

Which of the following are likely to occur as a result of overpumping groundwater?

*Land may subside. *Gaping fissures may open across the land surface. *Wells near to the well being overpumped may dry up.

Which of the following are common sources of groundwater contamination?

*Landfills *Ranches and farms *Service stations

If you had a choice of locating a septic tank on top of sandstone or limestone rock, which would be a better choice and why?

*Sandstone *It would filter the contaminants.

Rank the following steps in order from first detection of chromium in a groundwater sample, at the top, to its remediation, at the bottom.

1. Determine the geology of the site, the water-table depth, and direction of the flow of groundwater. 2. Drill additional wells for sampling of the groundwater for confirmation . 3. Drill wells in front of the plume of contamination and extract contaminated groundwater. 4. Process contaminated groundwater.

Which of the following statements correctly describes how a groundwater contaminant plume could be remediated?

A well is drilled in front of the projected plume path, pumping brings it to the surface for processing, and cleaned water is returned to the ground.

If a well has a cone of depression associated with it because of overpumping of the groundwater, what is a possible consequence?

Groundwater, which may contain pollutants, will flow toward the cone of depression and could cause a well to become polluted.

Which of the following choices best describes what happens to the flow of groundwater if a cone of depression is formed as a result of overpumping?

Instead of flowing in one direction, groundwater flows toward the cone of depression from all directions.

______ is the term used to describe the clean-up of a contaminated site, such as a gas station property with a leaking underground gas tank.

Remediation

Imagine a septic system located downgradient of a shallow well used for a domestic water supply at a small rural home. What might happen to groundwater flow if pumping in the well increased drastically?

The direction of water flow could change and the well would become contaminated with sewage.

What happens to the sediments that are in and below the dewatered zone of an aquifer?

The sediments become compacted.

True or false: Remediation is more expensive than not causing the contamination in the first place.

True

Which of the following is the leading cause of disease in Bangladesh?

Water contamination

As the water table drops, the upper section of the original aquifer is now ______ the water table and is dewatered.

above

When contamination enters groundwater, it typically moves ______.

along with the flowing groundwater, down the slope of the water table

The direction of groundwater flow can change dramatically across an area, becoming much more ______, if a cone of depression develops from overpumping.

centralized

If groundwater is removed from an aquifer by overpumping, a cone of __________ will form.

depression

Match the phrases to describe steps necessary in the tracking groundwater contamination.

determine the direction of groundwater flow> by creating a contour map of the water table. by creating a contour map of the water table. Use the chemical analysis data> to determine the shape and concentration of the contaminant plume. to determine the shape and concentration of the contaminant plume. Determine the rate of contaminant flow> using historical records and computer simulations using historical records and computer simulations

Dewatering of an aquifer occur when the water table ____

drops

Sediments in and below a dewatered area of an aquifer become compacted because water pressure ______.

drops, and the pore spaces are no longer held open

Subsidence occurs when groundwater is overpumped from an aquifer. In areas with nonporous rock, such as granite, which cannot be compacted, ______ develop.

fissures

When groundwater is overpumped, subsidence of the land may occur. In areas with unconsolidated sediments, compaction occurs, whereas in areas of solid bedrock,_________ in the rock develop, in order to accommodate for the change in surface elevation.

fissures, fractures, cracks, or joints

Some volatile organic compounds can be detected by geochemists in the field or lab because of the ______ the groundwater and/or soil samples.

gases emitted from

Farms, ranches, and commercial orchards are contributors to ______ contamination by using various chemicals, such as pesticides, fungicides, and fertilizers, that are not completely used up when applied, but residuals infiltrate into the ground surface.

groundwater

Rocks can naturally release contaminants such as sulfur, radon, and arsenic into the subsurface and any______ flowing through underground earth materials.

groundwater

A cone of depression will form if ______.

groundwater is overpumped from an aquifer

Saltwater_______ occurs if groundwater wells are overpumped along coastlines.

incursion or intrusion

Subsidence is ______ the elevation of the ground surface due to excessive pumping of underground liquids, such as groundwater.

lowering

As a result of ______, land may subside and gaping fissures may open across the land surface.

overpumping groundwater

During groundwater investigation, ______ parameters are studied.

physical and chemical

A(n)_________ is a term given to the shape of contamination as it follows the flow of groundwater and spreads out, like the smoke from a chimney.

plume

When contamination enters groundwater, it moves along with the direction of the groundwater. As it spreads out, the contamination takes on a particular shape called a ______.

plume

A common remediation method to clean up contaminated groundwater is called the "______-and-treat" method, where water is brought to the surface and then processed.

pump

If groundwater wells along coastlines are overpumped, then ______.

saltwater intrusion occurs

Contamination from the sewage outfall of a septic tank will be filtered if it passes into an area of ______ rather than an area of cavernous ______.

sandy layers; limestone

While taking some soil samples at an old manufacturing site, you suspect a sample is contaminated with volatile organic compounds because you_______ something suspicious even though you can't see anything different.

smell

The dropping of the ground-surface elevation due to compaction and the effects of overpumping of groundwater is called ______.

subsidence

In the past, Bangladesh had water contamination of ______, leading to widespread cholera and dysentery. Today, a major water contamination problem is ______.

surface-water sources from poor sanitation; arsenic poisoning from groundwater wells

Contamination typically flows with the groundwater, down the slope of the water________.

table