1 Groundwater Pollution Week 5 – 0407 Investigating the Site and Monitoring

2 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, Environmental-Engineering/1- 34Spring2004/CourseHome/ Environmental-Engineering/1- 34Spring2004/CourseHome/

3 revision of previous week

4 Information to help with the clean- up of contamination can be found at For example in.org/characterization/technologi es/solvr.cfmhttp://clu- in.org/characterization/technologi es/solvr.cfm helps decide what is the best characterization technique.

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6 You can click on the different technologies for more information.

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8 You can also look at each method.

9 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?

10 Q. What is a contaminant plume?

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

12 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.

13 Q. Give a meaning for phase.

14 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).

15 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.

16 Collecting vapor samples from contaminated areas in the unsaturated zone

17 Adsorption (n.)( 흡착 ) is when molecules of gas, liquid, or dissolved solids stick to a surface. Adsorb (v) Adsorbed (v. and adj)

18 Sorption

19 Contaminants could be in the saturated zone as: Dissolved ( 녹이다 ) in the groundwater Adsorbed onto the aquifer material Sitting on top of the bedrock (for dense nonaqueous phase liquids [DNAPLs]) Q. Draw diagrams of each of these.

20 NAPLs coat the Soil Particles

21 NAPLs fill the Voids

22 The first steps are called remedial ( 개선의 ) investigation ( 연구 ) (RI) activities ( 행위 ) Removal of contamination sources Doing some soil borings ( 구멍뚫기 ) Making groundwater monitoring ( 모니터 ) wells Soil sample collection and analysis Groundwater sample collection and analysis Aquifer testing

23 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

24 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? Waste Containment and Remediation Technology

25 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 Waste Containment and Remediation Technology

26 First steps in understanding a site 1. Understand geographic setting, topography, nearby water bodies 2. Get background geologic data Consult ground-water atlas of the area. Get reports on geology, hydrology, meteorology Check for reports from government geological surveys Waste Containment and Remediation Technology

27 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? Waste Containment and Remediation Technology

28 The following types of data are collected: Types of contaminants present in soil and groundwater Concentrations of contaminants in the samples Vertical and areal spread of contaminant plumes in soil and groundwater Vertical and areal spread of free-floating product or the DNAPLs Soil characteristics including the types of soil, density, moisture content, etc. Groundwater elevations Drawdown data collected from aquifer tests

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30 Engineering calculations help site remediation. These could include: Mass and volume of soil removed during tank removal Mass and volume of contaminated soil left in the vadose zone Mass of contaminants in the vadose zone Mass and volume of the free-floating product Volume of contaminated groundwater Mass of contaminants in the aquifer Groundwater flow gradient and direction Hydraulic conductivity of the aquifer

31 Understanding the geology and physical contaminants.

32 Geophysical Methods MethodObject Electrical resistivityMap conductive or nonconductive contaminants; stratigraphy Electromagnetic inductionMap conductive or nonconductive contaminants; metal objects; stratigraphy Seismic refractionStratigraphy (top of bedrock); depth to ground water Seismic reflectionHigh resolution mapping of top of bedrock Ground penetrating radar (GPR) Buried objects (plastic and metal); stratigraphy; depth to ground water MagnetometryBuried metal objects Gravity surveyOverburden thickness; landfill boundaries Waste Containment and Remediation Technology

33 Ground penetrating radar Waste Containment and Remediation Technology

34 Electromagnetic Induction Waste Containment and Remediation Technology

35 Electrical resistivity Waste Containment and Remediation Technology

36 Seismic reflection Waste Containment and Remediation Technology

37 Geophysics suite Waste Containment and Remediation Technology

38 Sampling the gas phase

39 Soil gas sampling system Waste Containment and Remediation Technology

40 Output from field GC Waste Containment and Remediation Technology

41 Soil gas survey results Waste Containment and Remediation Technology

42 There are two main methods of getting into the ground. - Drilling - Direct Push

43 Drilling deep test hole

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45 Drilling techniques Waste Containment and Remediation Technology

46 Hollow Stem Auger Waste Containment and Remediation Technology

47 Direct-push technology (Geoprobe) Waste Containment and Remediation Technology

48 Direct-push monitoring well Waste Containment and Remediation Technology

49 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

50 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

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

52 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

53 m in.org/characterization/technologies/solvr.c fm