by the Newsletter Team
As a follow-up to last issue’s hydrogeologic trivia questions, presented below are the next installment of questions, as well as the answers for the September quiz. And as a reminder, these questions are from the Social Hour Virtual Groundwater Trivia contest held last July, organized by Jane de Lambert.
- What is the deepest well we have a record for in our state, and in what County is it found?
- The use of bentonite-cement grout to seal a monitoring well results in a seal that is:
- more permeable than a bentonite grout
- more permeable than the sand pack
- less susceptible to cracking than neat cement grout
- more susceptible to failure than a bentonite grout above the water table
- What is the radial area of decreased water level around a pumping well called?
- You have been retained to identify the extent of groundwater contamination resulting from a truck rollover accident with a release of 1,000 gallons of trichloroethylene (TCE) two days ago. A large municipal well field, located about 1.5 miles from the accident site, produces groundwater from a carbonate aquifer. Regional stratigraphy, based on published sources and the well field stratigraphic logs, is characterized by: 0-20 ft below ground surface (bgs), unconsolidated sand and silty sand; 20-35 ft bgs, hard, blue-green clay; 35-100 ft bgs, weathered, fractured limestone. Water levels in the surficial aquifer are reported to be about 12 ft bgs. Monitoring wells installed at the accident site should be screened from:
- 75-100 ft bgs
- 5-15 ft bgs
- 10-20 ft bgs
- 15-40 ft bgs
- You are the geologist in charge responsible for designing a foundation exploration drilling program to be carried out in an area underlain by unconsolidated sediments containing large, granitic boulders. The site is known to be uncontaminated. Of the following, which would most likely be the fastest and most efficient drilling method?
- solid-stem auger drilling
- mud-rotary drilling
- direct-push drilling
- cable-tool drilling
- You have been asked to locate a public water supply well in a shallow, sand aquifer. Your locations are limited to three choices, all associated with land-use restrictions: Site 1 is 300 feet upgradient of a multi-acre, cattle feedlot. Site 2 is centered in an established residential neighborhood with 1/2-acre unsewered lots. Site 3 is 1,000 feet upgradient from a newly developed industrial park. In what order would you rank (best to worst) these three sites for installation of the new well?
- 1, 3, 2
- 3, 2, 1
- 3, 1, 2
- 1, 2, 3
Questions and Answers from the last Issue
- A groundwater model is considered calibrated when:
- the model grid and layers match the constructed conceptual model
- the groundwater flux into the model equals the groundwater flux out of the model
- hydraulic heads and fluxes reproduce the system modeled within an acceptable tolerance
- the chosen model boundaries express the nature of the physical boundaries
- In a steady state environment, a confined sand aquifer has a transmissivity of 40 m^2/d, thickness of 10m, and porosity of 20%. What is the hydraulic conductivity? 4 m/d
- What groundwater modeling system is Otto Strack famously known for creating? MLAEM or SLAEM/analytic element models
- What is the term for the unsaturated zone between the land surface and the water table? Vadose
- In an eolian sand aquifer, the hydraulic conductivity would be expected to generally
- increase upward
- increase downward
- be uniform
- be lowest in the middle of the unit
- The rate of production from a subsurface reservoir is most related to:
- porosity
- permeability
- compactness
- grain size
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