1 groundwater pollution week 5 – 0407 investigating the site and monitoring

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Groundwater Pollution

Week 5 – 0407 Investigating the Site and Monitoring

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Some Notes derived from

1.34 Waste Containment and Remediation Technology , As taught in: Spring 2004, by Dr. Peter Shanahan , MIT OpenCourseWare, Creative Commons License, http://ocw.mit.edu/OcwWeb/Civil-and-Environmental-Engineering/1-34Spring2004/CourseHome/

http://ocw.mit.edu/OcwWeb/Civil-and-Environmental-Engineering/1-34Spring2004/CourseHome/



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revision of previous week

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Information to help with the clean-up of contamination can be found at http://clu-in.org/ .

For example http://clu-in.org/characterization/technologies/solvr.cfm

helps decide what is the best characterization technique.

http://clu-in.org/

http://clu-in.org/characterization/technologies/solvr.cfm

http://clu-in.org/characterization/technologies/solvr.cfm

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You can click on the different technologies for more information.

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You can also look at each method.

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We then investigate the contaminant.Where is the contaminant plume?

What is in the plume?

How big is the plume?

How long has it been there?

Where is it going?

How fast will it go?

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Q. What is a contaminant plume?

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The contaminant plume is where the contaminant is dissolved in the ground water.

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Usually - The contaminant plume is where the contaminant is dissolved in the ground water.

Sometimes - It can also mean where the vapor is dissolved in the air.

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Q. Give a meaning for phase.

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Vadose zone

Floating

Groundwater

The phases are when the pollutant is solid (solid phase), liquid (liquid phase), vapor (gaseous phase), or dissolved in the water (aqueous phase).

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In the vadose zone contaminants could be present as:

Vapors in the void ( 공간 )

Free product in the void

Dissolved in the soil moisture ( 수분 )

Adsorbed ( 흡착하다 ) onto the soil matrix

Floating on top of the capillary fringe

Q. Draw a picture of each of the above.

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Collecting vapor samples from contaminated areas in the unsaturated zone

http://toxics.usgs.gov/photo_gallery/photos/bimidji/bimidji10_lg.jpg

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Adsorption (n.)( 흡착 ) is when molecules of gas, liquid, or dissolved solids stick to a surface.

Adsorb (v)

Adsorbed (v. and adj)

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Sorption

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Contaminants could be in the saturated zone as:Dissolved ( 녹이다 ) in the

groundwaterAdsorbed onto the aquifer materialSitting on top of the bedrock (for

dense nonaqueous phase liquids [DNAPLs])

Q. Draw diagrams of each of these.

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NAPLs coat the Soil Particles

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NAPLs fill the Voids

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The first steps are called remedial ( 개선의 ) investigation ( 연구 ) (RI) activities ( 행위 )Removal of contamination sourcesDoing some soil borings ( 구멍뚫기 )Making groundwater monitoring ( 모니터 ) wellsSoil sample collection and analysisGroundwater sample collection and analysisAquifer testing

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Questions to be answered by site

characterization

Nature and extent of contamination—

where is it?

What is future migration and control—

where is it going?

What are receptors and their risk—

what harm will it do?

What are technical options for remediation—

how do we fix it?

Waste Containment and Remediation Technology

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Data needed from site characterization

1. Contaminant sources – research history as well as collect samples

2. Extent of contamination – need to understand transport as well

3. Hydrogeologic setting – use to understand items 1 and 2

4. Restoration potential – how easy is it to clean up?


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Stages of investigation

Stage 1 – scoping study

Is there a problem? How bad is it?

Stage 2 – prepare field study plan

Includes sampling and analysis, health and safety, and quality assurance plans

Stage 3 – conduct on-site sampling and analysis

Stage 4 – interpretation, assessment, modeling

(Stages 3 and 4 may be repeated several times)

Stage 5 – design remedial action


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First steps in understanding a site1. Understand geographic setting, topography, nearby water bodies2. Get background geologic dataConsult ground-water atlas of the area.Get reports on geology, hydrology, meteorologyCheck for reports from government geological surveys


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First steps in understanding a site

3. Understand site use and history

Where were chemicals handled or disposed?

What site structures or activities are potential sources?

What chemicals are and were handled?


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The following types of data are collected:Types of contaminants present in soil and

groundwaterConcentrations of contaminants in the

samplesVertical and areal spread of contaminant

plumes in soil and groundwaterVertical and areal spread of free-floating

product or the DNAPLsSoil characteristics including the types of

soil, density, moisture content, etc.Groundwater elevationsDrawdown data collected from aquifer tests

29http://mn.water.usgs.gov/bemidji/results/fact-sheet.pdf

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Engineering calculations help site remediation.

These could include:Mass and volume of soil removed during tank

removalMass and volume of contaminated soil left in

the vadose zoneMass of contaminants in the vadose zoneMass and volume of the free-floating productVolume of contaminated groundwaterMass of contaminants in the aquiferGroundwater flow gradient and directionHydraulic conductivity of the aquifer

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Understanding the geology and physical contaminants.

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Geophysical Methods

Method ObjectElectrical resistivity Map conductive or nonconductive

contaminants; stratigraphy

Electromagnetic induction Map conductive or nonconductive contaminants; metal objects; stratigraphy

Seismic refraction Stratigraphy (top of bedrock); depth to ground water

Seismic reflection High resolution mapping of top of bedrock

Ground penetrating radar (GPR)

Buried objects (plastic and metal); stratigraphy; depth to ground water

Magnetometry Buried metal objects

Gravity survey Overburden thickness; landfill boundaries


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Ground penetrating radar


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Electromagnetic Induction


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Electrical resistivity


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Seismic

reflection


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Geophysics

suite


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Sampling the gas phase

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Soil gas sampling system


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Output from field GC


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Soil gas survey results


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There are two main methods of getting into the ground.

- Drilling

- Direct Push

43Drilling deep test hole http://nevada.usgs.gov/adrs/images/photos/studyareas/StudyAreasandExperimentalS/study9.html

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Drilling techniques


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Hollow Stem Auger


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Direct-push

technology

(Geoprobe)


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Direct-push monitoring well


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Direct push - Advantages • Inexpensive to install, replace and

abandon• Minimal waste “cuttings”• Fewer well development wastes• Rapid installation and site

characterization• Less worker exposure to contaminants• Representative chemistry and field

parameter measurements• Improved landowner relations

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Direct push - Disadvantages • Not applicable when cobbles or

consolidated materials are present• May not be accepted for long term

monitoring in most states• Debate remains regarding aquifer

testing capabilities• Well diameter limitations• Pump diameter limitations• Potential for higher turbidity in

wells with no filter pack

51Demonstration/Validation of Long-Term Monitoring Using Wells Installed by Direct Push Technologies and Enhanced Low-Flow Groundwater Sampling Methods. DoD 2009

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Percentage Savings for DP Well Installations Based on Well Diameter and Depth.

Demonstration/Validation of Long-Term Monitoring Using Wells Installed by Direct Push Technologies and Enhanced Low-Flow Groundwater Sampling Methods. DoD 2009

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http://www.frtr.gov/decisionsupport/index.htm

http://www.clu-in.org/characterization/technologies/solvr.cfm





1 groundwater pollution week 5 – 0407 investigating the site and monitoring

Documents

monitoring slide

34spring2004coursehome

sorption slide

adj slide

remediation technology

analysis aquifer testing

contaminant plume

liquid liquid phase