Groundwater

Question 1

What is groundwater?

Answer 1

-water found below the Earth’s surface, filling porous spaces in soil and rock
-fresh water from rain or melting snow and ice that is stored between rocks and particles of soil (infiltration)
-provides 25% of the fresh water used in the US
-can stay underground for decades or can come to the surface to fill rivers, streams, lakes, ponds, and wetlands (outcroppings, recharge)
-can move slowly
-also can come to the surface as a spring or be pumped from a well

Question 2

Relative quantity of groundwater vs surface water

Answer 2

-10 million cubic kilometers of water stored underground

Question 3

Groundwater zones

Answer 3

unsaturated zone, water table, saturated zone, groundwater

Question 4

What is surface water?

Answer 4

-surface water is water that collects on the ground or in a stream, river, lake, reservoir or ocean
-surface water is constantly replenished through precipitation and lost through evaporation, plant uptake, ag, DW
-approx 68% of community water system users receive their water from a surface water source
-surface water is any body of water above ground, including streams, rivers, lakes, wetlands, reservoirs, wetlands and creeks
-the ocean, despite being salt water is also considered surface water
-surface water is part of the water cycle, which involves the movement of water to and from the Earth’s surface
-surface water and ground water are reservoirs that can feed into each other. Surface water can seep underground to groundwater and groundwater can resurface on land to replenish surface water

Question 5

unsaturated zone

Answer 5

the portion of the subsurface above the groundwater table. The soil and rock in this zone contains air as well as water in its pores. In some places the unsaturated zone is absent, as is common where there are lakes and marshes, and in some places it is hundreds of meters thick, as is common in arid regions

Question 6

water table

Answer 6

the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the locality. It can also be simply explained as the depth below which the ground is saturated

Question 7

saturated zone

Answer 7

the part of an aquifer, below the water table, in which relatively all pores and fractures are saturated with water.

Question 8

unconfined aquifer

Answer 8

the upper layer of an aquifer which does not have a confining layer of solid material above it

Question 9

confined aquifer

Answer 9

ground water sources under pressure from the weight of rocks that have layers of solid material above and below them causing pressure

Question 10

artesian well

Answer 10

groundwater aquifers between layers of rock that are confined and under pressure. If tapped by a well, water will rise above the top of the aquifer

Question 11

What is an aquifer?

Answer 11

an underground layer of water-bearing material, consisting of permeable or fractured rock, or of unconsolidated materials

Question 12

outcrop

Answer 12

rock walls along roadsides where the rock is exposed and water maybe seen seeping out of the cracks of the rock unit. This rock wall represents an “outcrop” (or location where the rock intersects the land surface) of an aquifer

Question 13

groundwater recharge: natural

Answer 13

-occurs as precipitation falls on the land surface, infiltrates into soils, and moves through pore spaces down to the water table
- can occur as surface water leakage from rivers, streams, lakes and wetlands

Question 14

groundwater recharge: artificial

Answer 14

recharge can be done through injection of water through wells
-this has the problem of potentially introducing contaminants

Question 15

groundwater contamination: point sources

Answer 15

sources that might include wastewater treatment plants, landfills, garages, motor pools and fleet maintenance facilities. other sources include mine discharge water and mine spoil run-off

Question 16

groundwater contaminaion: nonpoint sources

Answer 16

sources that might include excess fertilizers, herbicides and insecticides from agricultural lands and residential areas. Oil, grease and toxic chemicals from urban runoff and energy production. Sediment from improperly managed construction sites, crop and forest lands, and eroding streambanks

Question 17

What is a public water system?

Answer 17

-EPA can establish standards for drinking water and requires owners/operators of public water systems to comply with them
-these can contain: -source of water -surfacewater or groundwater
-treatment-to remove contaminants to meet standards
-storage -post treatment before distribution
-distribution-industrial and residential,etc
must have at least 15 service connections or serve at least 25 people per day for 60 days of the year
-water standards apply to water systems differently based on their type and size

Question 18

What is the community public water supply?

Answer 18

public water system that serves the same people year-round (eg-houses, apartments, condominiums in cities, small towns)

Question 19

What are non community public water supplies?

Answer 19

a public water system that serves the public but does not serve the same people year-round such as schools, businesses, hospitals

Question 20

What populations are served by groundwater?

Answer 20

smaller communities
-can have thousands of treatment systems

Question 21

What populations are served by surface water?

Answer 21

larger communities
- served by fewer treatment systems

Question 22

primary drinking water standards

Answer 22

-legally enforceable standards that apply only to public water systems (not private systems)-subject to fines and penalties if these are not met
-protect drinking water by limiting the levels of specific contaminants that affect public health (affect only the public water supply)
-intended to minimize public health risks
-expressed as MCL’s
-maximum contaminant levels (MCL’s) or treatment technique rules (TTR)
HW-acute vs chronic what is always the higher allowable level of a contaminant

Question 23

secondary drinking water standards

Answer 23

-non-enforceable guidelines for contaminants that may cause:
-cosmetic effects (such as skin or tooth discoloration)
-aesthetic effects (such as taste, odor, or color) in drinking water
-EPA recommends secondary standards but does not require systems to comply however, states may choose to adopt them as enforceable standards or make them more stringent

Question 24

MCLG

Answer 24

-maximum containment level goal
-the maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, allowing an adequate margin of safety to reflect uncertainty
-set by the EPA but state can always make it more stringent

Question 25

MCL

Answer 25

-maximum containment levels that are regulated
-dependent on the available technology to achieve the required level
-the highest level of a contaminant that is allowed in drinking water based on cost benefit analysis and is enforceable.

Question 26

Chemical contaminants

Answer 26

-naturally occurring or manmade. Examples include nitrates, chlorine, salts, pesticides, metals (arsenic, lead), and human or animal drugs (antibiotics, endocrine distruptors, hormones)

Question 27

radiological contaminants

Answer 27

-naturally occurring or man made that can emit ionizing radiation. Examples include cesium, plutonium and uranium
-Drinking water with
radionuclides can cause toxic kidney effects and
increase the risk of cancer.

Question 28

microbial contaminants

Answer 28

-organisms in water
-water may contain bacterial diseases such as typhoid and cholera and waterborne viruses
-other biological or microbial contaminants include viruses, protozoa and parasites
-People that consume drinking water
containing microorganisms can experience
gastrointestinal illnesses and infections

Question 29

disinfection byproducts

Answer 29

-method of disinfection is the addition of chlorine to drinking water
-chlorine kills waterborne bacteria and viruses and continues (chlorine residuals) to keep the water safe as it travels from the treatment plan to the consumer
- Chlorine can react with organic materials in water
to form disinfection byproducts (DBPs)
-Some may experience problems with their liver,
kidneys, or central nervous system and may have
an increased risk of getting cancer from DBPs.

Question 30

How many containment values are regulated by the EPA?

Answer 30

-94 contaminants currently regulated.
i. Approx. 60,000 potential contaminants
ii. Considers adverse human health effects.
iii. Probability of occurrence in DW
iv. Opportunity to reduce HH effect in PWS.

Question 31

CCL- Candidate Containment List

Answer 31

i. Contaminants that may require future regulation.
ii. Compiled every 5 years.
iii. Prioritized by greatest HH risk.

Question 32

Potential Threats to Human Health Disease by Contaminant Category

Answer 32

i. Chemical -e.g., Lead
ii. Microbial – e.g., Vibrio, E. coli, Salmonella, Cryptosporidium
iii. DBP – e.g., Chlorine + Ammonia (Organic material) = Chloramines – potentially carcinogenic