Water (on Final) Flashcards
Where does ground water occur?
Geological formations and soils beneath water table
-stored in a layer of permeable rock, sand or gravel =aquifer
Characteristics of ground water:
- nearly oxygen free
- Ions at lowest valence
- doesn’t contain particulates
What is movement of groundwater influenced by
- gravity
- pressure
- porosity
What does Darcy’s law describe?
Flow of a body of water through a porous medium, namely that the porous medium will influence how contaminants are transported
What is for distance traveled by groundwater? What are the parameters that effect this?
Millimeters per day - meters per day
Parameters: gravity, pressure and friction
Explain parts of equation:
Q= K * (🔼H * A * t/ z)
Q=vol of water moving through soil column (m3)
K = hydronic conductivity (m/day)
🔼H = hydronic head difference between inlet and outlet (m)
A=cross sectional area of the soil column (m2)
T=time (d)
Z=length of the soil column (m)
What is sampling of groundwater affected by? What must the analyst obtain before sampling?
- aquifer depth, recharge rate, soil permeability, topography, and type of analyte (such as volatility or persistence)
- obtain: history/geology of site, physical/chem characteristics of aquifer system
What do you have to do before sampling groundwater wells? Why?
Purge stagnant water.
Not representative of water from aquifer
What does method, rate, time between purging and sampling, and sampling depend on in regards to ground water wells?
Wells diameter, depth and recharge rate
What should you do to estimate the extent and Rae of purging prior to sampling?
Slug, and pressure or pump tested to determine hydronic conductivity of formation
What does a standard purge volume obtain? What is the usual range?
A stabilized concentration or the parameter of interest.
Ranges from 3-10 well volumes
What should be stabilized before a sample is taken from a ground water well?
pH, conductivity, and temp
What does a piezometer do?
Measured fluid pressures such as groundwater elevations and pore pressures when buried directly in embankments and fills
What are sources of water found and sampled from?
- surface water (rivers, lakes, runoff, ponds, streams,and reservoirs)
- groundwater (monitoring wells and drinking water)
- spring water
- wastewater
- ice
- also brine, saline, process, potable and estuarine water
What does class 1 water mean?
Potable water supply
What does class 2 water mean?
Shellfish propagation and harvesting
What does class 3 water mean?
Recreational propagation and maintenance of fish and wildlife
What does class 4 water mean?
Agricultural water supply
What does class 5 water mean?
Navigation, utility and industrial use
In rivers and streams the type and number of samples depends on:
- width
- depth
- discharge point
- amount of suspended sediment
- aquatic life present
What is the best type of sample to determine the maximum concentration of contaminant
A discrete grab sample
How do you take a sample from very shallow water(<0.5m)?
Wade out, collect sample upstream
To make sample more representative, what can an analyst do?
Compositing samples from different depths, as directed by sampling plan.
Factors to consider when sampling in rivers and streams
- Accessibility
- point if contamination
- flow rate
- changes in channel
- type of bed, depth and turbulence
- structure present
- safety
Factors to consider when sampling lakes
- accessibility
- special stability
- thermal stability
Factors to consider when sampling groundwater
- site of contamination
- purification/treatment process
