Description
This work focuses on a generalized assessment of source zone natural attenuation (SZNA) at chlorinated aliphatic hydrocarbon (CAH) impacted sites. Given the numbers of sites and technical challenges for cleanup there is a need for a SZNA method at CAH impacted sites. The method anticipates that decision makers will be interested in the following questions: 1-Is SZNA occurring and what processes contribute? 2-What are the current SZNA rates? 3-What are the longer-term implications? The approach is macroscopic and uses multiple lines-of-evidence. An in-depth application of the generalized non-site specific method over multiple site events, with sampling refinement approaches applied for improving SZNA estimates, at three CAH impacted sites is presented with a focus on discharge rates for four events over approximately three years (Site 1:2.9, 8.4, 4.9, 2.8kg/yr as PCE, Site 2:1.6, 2.2, 1.7, 1.1kg/y as PCE, Site 3:570, 590, 250, 240kg/y as TCE). When applying the generalized CAH-SZNA method, it is likely that different practitioners will not sample a site similarly, especially regarding sampling density on a groundwater transect. Calculation of SZNA rates is affected by contaminant spatial variability with reference to transect sampling intervals and density with variations in either resulting in different mass discharge estimates. The effects on discharge estimates from varied sampling densities and spacings were examined to develop heuristic sampling guidelines with practical site sampling densities; the guidelines aim to reduce the variability in discharge estimates due to different sampling approaches and to improve confidence in SZNA rates allowing decision-makers to place the rates in perspective and determine a course of action based on remedial goals. Finally bench scale testing was used to address longer term questions; specifically the nature and extent of source architecture. A rapid in-situ disturbance method was developed using a bench-scale apparatus. The approach allows for rapid identification of the presence of DNAPL using several common pilot scale technologies (ISCO, air-sparging, water-injection) and can identify relevant source architectural features (ganglia, pools, dissolved source). Understanding of source architecture and identification of DNAPL containing regions greatly enhances site conceptualization models, improving estimated time frames for SZNA, and possibly improving design of remedial systems.
Details
Title
- Source zone mass depletion of chlorinated aliphatic hydrocarbons: estimation of rates and insight into source architecture
Contributors
- Ekre, Ryan (Author)
- Johnson, Paul Carr (Thesis advisor)
- Rittmann, Bruce (Committee member)
- Krajmalnik-Brown, Rosa (Committee member)
- Arizona State University (Publisher)
Date Created
The date the item was original created (prior to any relationship with the ASU Digital Repositories.)
2013
Subjects
- Environmental engineering
- Mass Discharge
- Natural Attenuation
- Sampling density
- Sampling Guidelines
- Source Architecture
- Source Zone Depletion
- Chlorohydrocarbons--Environmental aspects.
- Chlorohydrocarbons
- Aliphatic compounds--Environmental aspects.
- Aliphatic compounds
- Hazardous wastes--Natural attenuation.
Resource Type
Collections this item is in
Note
- Partial requirement for: Ph. D., Arizona State University, 2013Note typethesis
- Includes bibliographical references (p. 156-169)Note typebibliography
- Field of study: Civil and environmental engineering
Citation and reuse
Statement of Responsibility
by Ryan Ekre