Superfund Site Uses GIS for Groundwater Analysis

Puente Valley Gets Better Environmental Assessment Using GIS

Performing environmental assessment and locating environmentally contaminated areas is no small matter. That's why the EPA created its Superfund program.

The program was established in 1980 to help the EPA locate areas where environmental cleanup was necessary and to facilitate cooperation among organizations working to perform a number of environmental mitigation activities. The result was the identification of a number of sites across the country that needed detailed analysis of information for a number of application areas. And at the Puente Valley Operable Unit (PVOU) of the San Gabriel Valley Superfund sitein California, GIS is making a difference.

A Puente Valley industry group selected Daniel B. Stephens & Associates, Inc. (DBS&A), an Esri Business Partner, to provide technical assistance in mediating an allocation of remedial costs for cleaning up groundwater in the PVOU.

The San Gabriel Valley sites cover areas with contaminated groundwater in the 170-square-mile San Gabriel Valley. The contaminated areas are under segments of Alhambra, Arcadia, Azusa, Baldwin Park, City of Industry, El Monte, La Puente, Monrovia, Rosemead, South El Monte, West Covina, and other areas of the San Gabriel Valley.

First discovered in 1979, the contaminated areas contain what are called volatile organic compounds (VOCs), which were first detected by Aerojet Electrosystems. Following the discovery, the California Department of Health Services (CDHS) began investigating surrounding areas to discover the extent of the problem. By 1984, 59 wells were discovered contaminated with VOCs.

While pinpointing the exact cause was not possible, it was known that hundreds of facilities may have contributed to the contamination, mainly through past Business practices and, now, the groundwater's failure to meet strict EPA water quality standards. This groundwater provides nearly 90 percent of the localized water supply for over 1,000,000 people in the area. Indeed, more than 400 wells were once used for industrial, Business, agricultural, and domestic water purposes.

To begin working the task assigned, DBS&A had to manage and analyze a large volume of groundwater chemistry data—roughly 250,000 records—from approximately 1,000 wells used to sample and analyze groundwater in the PVOU.

Founded in 1984, DBS&A, based in Albuquerque, New Mexico, provides environmental consulting including a full range of services in surface and groundwater hydrology and civil and environmental engineering.

DBS&A conducts hydrogeologic investigations, contaminant transport studies in soil and groundwater, environmental assessments, numerical modeling, field and laboratory testing of soils, and remediation of soil and groundwater. DBS&A has established a special expertise and reputation in the unsaturated layer known as the vadose zone, which plays a vital role in protecting or restoring groundwater quality.

DBS&A is using ArcView GIS, along with a variety of Avenue utilities the company developed, for analysis and visualization of a wealth of data including the soil, chemical, and groundwater data related to the PVOU.

"Primarily, we are interested in looking at concentrations of specific chemicals over time periods in all 1,000 wells," says David Jordan, program manager and senior hydrogeologist, DBS&A. "We are using ArcView GIS to query and post the data, and then we produce maps showing contaminant plumes in groundwater. Four to five people are regularly using ArcView GIS on this project, and we have loaded the data on a laptop so that we have access to it during the mediation sessions."

GIS is used to plan who will assist in specific areas of cleanup, associated costs, and other environmental cleanup applications. Data collected by the EPA is made available at an FTP site where DBS&A extracts the data, cleans it up, and adds additional information to the data set. DBS&A then analyzes specific chemical concentrations of interest such as trichloroethylene (TCE).

The groundwater data is collected by drilling pipes into the ground until they tap into the underground water table. Water is extracted and a sample is sent to a laboratory where it is analyzed. "We can use GIS to find out where the contamination is and where it is coming from," says Jordan.

Previous to their use of ArcView GIS, the company used CAD systems to produce similar maps. "We couldn't process the amount of information that we can now, nor could we process it as quickly," says Jordan. "For instance, if we want to look at TCE in January of 1994, we can query the database, post the data on a map, label it on a map, and proceed. In the past, this would have been a very laborious process."

In addition, for environmental sites such as the PVOU, many companies keep records and documents in various formats. According to DBS&A, another benefit of GIS is the ability to integrate these reports and store the data in one place where it can be managed and analyzed. A single database replaces volumes of paper reports and notebooks.

"The advent of desktop GIS, and ArcView GIS in particular, has allowed us to manage and analyze large environmental data sets that we were not able to efficiently and effectively manage previously," says Jordan. "Since we work quite a bit on environmental projects that are litigious in nature, GIS allows us to put data from many different data sources together and analyze them as a whole. The GIS also allows very rapid map production."

In addition, the company sees an advantage of using GIS as an effective visualization tool to present the data. For instance, DBS&A can overlay soil or groundwater data on an aerial photograph to help show how the contaminated areas correspond with sites that might be responsible for the contamination.

According to DBS&A, data precision is fundamental to any GIS project. "The accuracy of the database is key," says Jordan. "It is without a doubt very worthwhile to spend a little extra time and money at the beginning of the project to make sure that proper QA/QC procedures are followed during database development."

The success of the use of GIS at the Puente Valley site has led DBS&A to acquire GIS-trained staff to meet the increased demand for GIS services. "In approximately three years, we have evolved from having no formal GIS staff to having two full-time GIS staff as well as numerous staff scientists who are using GIS regularly," says Jordan. "By using a database to manage map data, we get improved methods for using information, not only for the PVOU, but also for our many other diverse environmental projects."

For more information contact Kenny Calhoun, GIS Manager, Daniel B. Stephens & Associates (tel.: 505-822-9400, e-mail: dbsa@dbstephens.com).

ArcNews home page