Subsurface Stratigraphy at Marcus Hook Using EQuIS Geology
Objective
Background
What is EQuIS Geology?
Marcus Hook Data
Using ArcView to View Subsurface Data
Future Efforts
Objective The goal of this project was to create a tool that would facilitate the visualization of subsurface data through the ArcView GIS platform. Although data from the Marcus Hook Refinery was used to develop and demonstrate this application, the objective was oriented more towards building a tool that could be used in any ArcView GIS project to visualize subsurface data than analyzing the geology specific to the Marcus Hook Refinery area.
The capability to visualize subsurface data through ArcView was realized by using three separate components:Background
The Marcus Hook Refinery is a facility located in Marcus Hook, Pennsylvania, adjacent to the Delaware River. It was owned and operated for many years by British Petroleum and was sold two years ago to Tosco. BP agreed to take responsibility for the remediation of any environmental problems that existed at the site at the time of the sale. This project involves cooperation between the BP Environmental Remediation office in Atlanta, Georgia, representatives of RUST environmental services in Pennsylvania who are monitoring current conditions at the site, and researchers from the University of Texas at Austin directed by Dr. David Maidment and Dr. Robert Gilbert. Additional data will be provided by other BP contractors, including information on aerial surveys and a tabular environmental database compiled for the site. While extensive research has been conducted at The University of Texas at Austin in the areas of using a GIS system as the framework for risk-based corrective action and developing a conceptual model and decision analysis framework, investigating the subsurface characteristics of the area is a task that has received little attention. For this reason, it is hoped that this research might provide some insight and facilitate a more efficient characterization effort of the Marcus Hook area.What is EQuIS Geology?
EQuIS Geology is a complete subsurface data management application that allows the user to store a host of geologic and hydrogeologic data in relational database environment.
In the preceding diagram, the colored vertical line represents a boring location in a hypothetical site scenario which will be used to explain the data models. Each of the listed parameters are a component of the description of this location.
Subsurface point data is defined as data along a trace (typical linear and vertical or near-vertical) where various characteristics are measured at discrete locations. While cone penetrometer testing (CPT) data is subsurface point data, this category includes any form or method of data collection that is similar.
This diagram shows our site where certain parameters are measured at specific locations. It is assumed that parameters that are observed have a definite value at the location of each measurement.
Where observations of material type or material parameters are observed and assumed constant over a given interval, these data are considered subsurface segment data. One of the most common forms of subsurface segment data is stratigraphy.
Stratigraphy data is typically continuous, although it does not need to be. Stratigraphy data may be identified by the standard material classifications (USCS, USDA, AASHTO) as well as common mineral and petroleum resources. Additionally, user-defined materials and material groups may be established. Each stratigraphy layer may be described by two separate descriptive remarks.
Whereas the subsurface is often characterized in a small-scale manner by drillers or geologists delineating every unique layer of sand, silty sand, or sandy clay, this scheme may be cumbersome or inadequate for modeling or other applications. A solution is provided by assigning each stratigraphy layer a geologic unit such as ‘Aquifer’ and ‘Bedrock’. Geologic units allow a regional-scale characterization that may be more conducive to analytical modeling.
Samples may be obtained by any of the typical sampling methods used, which method is also stored. For each sample taken field parameters such as OVA/PID (Organic Vapor Analysis/Photoionization Detector) or lab parameters (hydraulic conductivity, unit weights, Atterberg limits, etc.) may be associated.
Well data information includes both well construction details and transient water level measurements.
EQuIS Geology is a consistent and comprehensive data management environment, and allows the user to export data to many different visualization and analysis systems. While the possibilities for data usage are limitless some of the most common applications include borehole logs, groundwater modeling, three-dimensional solid models, and cross-sections/fence diagrams.
Borehole Logs
Manual creation of data files is at best an arduous and error-prone task. EQuIS Geology automates creating these files by selected the data of interest and clicking a button. Professional borehole logs can be created quickly and easily. Current interfaces include LogPlot from RockWare and gINT from GCA.
GMS users can also utilize water level data to automatically construct an observation coverage for model calibration.
Three-Dimensional Visualization
One of the most effective methods of presenting subsurface information is using a three-dimensional solid model, cross-section, or fence diagram. These objects can be created using RockWare’s Stratos, GMS, or EVS by CTech.
Marcus Hook Data
The GIS data available from Marcus Hook was somewhat misleading and problematic. There were a number of coverages which implied stratigraphy information would be available but did not, in fact, have stratigraphy information. These included the Borings, SoilBorings, BHBorings, and Monitwells coverages. While some few of these locations had stratigraphy, many did not. This being the case, it was necessary to create an additional event theme containing locations which had stratigraphy data. This was done by a simple query to select the locations that existed in the Location and Stratigraphy tables: SELECT DISTINCT Location.LOC_ID, Location.northing, Location.easting FROM Location, stratigraphy WHERE location.loc_id=stratigraphy.loc_id;Using ArcView to View Subsurface Data
Once the proper themes had been established in ArcView, the next step was to extract stratigraphy from the EQuIS Geology database and invoke the requisite application. The customization of ArcView involved adding and "EQuIS Geology" menu to the view with the following options:
The scripts behind each of these menu options were very similar in that they each created a simple text file including the function, path to the third-party application, number of boreholes, and list of borehole IDs. The following text is an example of a file used to display the stratigraphy of seven boreholes in GMS:
gmsThe scripts then lauched another program, a derivative of EQuIS Geology, which pulled the appropriate data from the database and launched the designated application.
The following figures resulted from viewing Marcus Hook stratigraphy using the ArcView interface. This figures are not intended to imply any type of analysis or solution, but simply to represent the kind of output obtainable through using the ArcView interface. View Stratigraphy:
Boring Log:
Fence Diagram:
Cross-section:
EVS Geology:
Future Work
I would like to continue the work discussed in this project by improving the usability of the ArcView interface. This would include making the functionality non-project specific. This would involve providing a place for the user to indicate paths to the applications they intended to use for visualization and analysis. Generalizing the view and allowing the user to specify which field in the attributes table corresponds to the x and y locations is also a critical part of generalization. Finally, I intend to incorporate this functionality into an extension that can be used as any other ArcView extension.