Background:
A small community pumps groundwater from a confined sandstone aquifer for their drinking water supply. A recent monitoring study, however, shows that the aquifer is contaminated by a TCE plume near the Boeing and Cascade sites upgradient (see below). Although the well water is currently not contaminated, the citizens are extremely concerned since groundwater is their exclusive source of water supply.
Figure 1: Contamination sites, water supply wells and major surface water bodies in the study area.
Figure 2: Conceptual cross-section of the hydrogeology of the study area.
Questions:
The fact that groundwater is invisible make them particularly anxious and has been asking many questions:
- Will the advancing plume hit the community wells? How long does it take for the plume to reach the wells?
- Will the community pumping affect the plume migration? What is the influence area of the community wells?
- What is the safe yield of the community wells? (The safe yield is defined as the maximum pumping rate that can be used without attracting contaminants).
- How can the community develop a wellhead protection program that protects the community water supply?
Objective and Data:
Suppose you are hired as a consultant by the local citizens. Develop a quantitative analysis to address the aforementioned questions based on the following data available from earlier studies:
- Current pumpage from each well 80 GPM
- Effective porosity = 0.2
- Recharge in the area is approximately 5 inch/year
- Overbank deposits conductivity, 5 ft/day
- Sandstone aquifer top elevation: -10 m
- Average aquifer thickness, 50 m
- Average hydraulic conductivity of the sandstone, 150 ft/day
- Blue Lake – stage: 3.3m, bottom elevation, -1.7 m, leakance 0.157/day
- Fairview Lake – stage 3.5 m, bottom elevation, 0.1 m, leakance 0.154 /day
- Columbia River, stage 3m, fully connected with both the shallow and deep aquifers
- General regional flow direction: north towards the Columbia River
Tool for Analysis:
Visit the following website to develop and apply a groundwater model of the study area:
https://www.magnet4water.com/magnet/
A georeferenced site map (Figure 1) is available for overlaying in the MAGNET modeling environment. It is included in the problem posting on the MAGNET Curriculum Network.
Also included is the ‘Site_wells_contamination_extent.txt’ file which includes the image spatial extents needed for overlaying in the modeling environment.
Deliverable:
Document your analysis in a short report / memo. The report/memo should or be supplemented with (as an attachment) the following elements: background, objectives, approach, conceptual representation, numerical scheme, modeling inputs/assumptions, results, and conclusions.
Questions:
The fact that groundwater is invisible make them particularly anxious and
has been asking many questions:
- Will the advancing plume hit
the community wells? How long does it take for the plume to reach the
wells?
- Will the community pumping
affect the plume migration? What is the influence area of the community
wells?
- What is the safe yield of the
community wells? (The safe yield is defined as the maximum pumping rate
that can be used without attracting contaminants).
- How can the community develop
a wellhead protection program that protects the community water supply?
Objective
and Data:
Suppose you are hired as a
consultant by the local citizens. Develop a quantitative analysis to address
the aforementioned questions based on the following data available from earlier
studies:
- Current pumpage from each well 80 GPM
- Effective porosity = 0.2
- Recharge in the area is approximately 5 inch/year
- Overbank deposits conductivity, 5 ft/day
- Sandstone aquifer top elevation: -10 m
- Average aquifer thickness, 50 m
- Average hydraulic conductivity of the sandstone, 150 ft/day
- Blue Lake – stage: 3.3m, bottom elevation, -1.7 m, leakance 0.157/day
- Fairview Lake – stage 3.5 m, bottom elevation, 0.1 m, leakance 0.154 /day
- Columbia River, stage 3m, fully connected with both the shallow and deep aquifers
- General regional flow direction: north towards the Columbia River
Tool for Analysis:
Visit the following website to develop and apply a groundwater model of the
study area:
https://www.magnet4water.com/magnet/
A georeferenced site
map (Figure 1) is available for overlaying in the MAGNET modeling environment.
It is included in the problem posting on the MAGNET Curriculum Network.
Also
included is the ‘Site_wells_contamination_extent.txt’ file which includes the
image spatial extents needed for overlaying in the modeling environment.
Deliverable:
Document your analysis in a short report / memo. The report/memo should or
be supplemented with (as an attachment) the following elements: background, objectives,
approach, conceptual representation, numerical scheme, modeling inputs/assumptions,
results, and conclusions.