Resource-Effective Management for Multi-Agency Projects through GIS as Implemented in the Downtown Tucson Groundwater Study

Donna Nelson and Alan Dulaney, Arizona Department of Environmental Quality

The Downtown Tucson Technical Group represents a cooperative effort of several governmental agencies and interested parties to investigate and clean up a widespread contaminant plume. Groundwater in two aquifers under downtown Tucson is contaminated with petroleum hydrocarbons and volatile organic compounds, and the commingled plume cuts across many properties. The problem lies in the coordination of investigative and remedial activities by several parties in a cooperative manner so that corrective actions become more efficient. The answer involves the utilization of ArcInfo as a means of sharing data and better understanding the problem. GIS offers the most effective way of visualizing the project and its associated spatial variables such as recharge zones, diverse sets of facilities, widely scattered sampling points, and others. Covers illustrate the project area, wells installed into both the upper and regional aquifers, the known extent of diesel and VOC contamination in both aquifers, and different types of facilities within the project area. Because the plume is still not fully characterized, areas of critical data gaps where more investigation is needed are also shown. Current remedial activities involve removal of free petroleum product from several wells completed into the uppermost aquifer. Because the flow of information between investigators is essential to the success of this project, ArcInfo is envisioned as a major management tool to foster cooperation in the investigation and cleanup of this large plume. Without ArcInfo it is doubtful that any significant coordination between investigators could be achieved, and duplication of activities would increase remediation costs significantly, thereby having negative impact on all concerned.


Combining Mapping Technologies to Determine Soil Permeability for NPDES

Michael D. Stevens, Bob Shanks, and Hugh Dodd, Hammon, Jensen, Wallen and Associates

In an effort to recoup some of the costs of administering the EPA NPDES (National Pollutant Discharge Elimination System), the City of Menlo Park wanted to assess parcels based on a percent of their nonpermeable land. Conventional methods of house-by-house field survey or photogrammetric collection of every impervious feature would be excessively costly. A new faster and more cost-effective method was used. Hammon, Jensen, Wallen, and Associates of Oakland, California, used an airborne multispectral scanning system to scan images of the entire City in a manner similar to collecting stereo aerial photography. The scanned images were controlled and ortho-rectified using results of an additional 1:12,000-scale black-and-white aerial flyover. The ortho-rectified, multispectral imagery tiles were seamlessly mosaicked into a single image, then reclassified so that pervious and impervious features were separated. The resulting color bands were converted into a GIS raster file, then automatically outlined into GIS polygons that were overlaid with the City's parcel layer to determine the percent of impermeable land within each parcel. Cost savings are approximately 50 percent over traditional methods.


Groundwater Circulations Recognized By Tracing in State of Neuchatel (Switzerland)

Mahmoud Bouzelboudjen, Francois Burri, and Pascal Ornstein, Centre of Hydrogeology - University of Neuchatel

In practice, anyone managing groundwater systems is faced with various problems related thereto: pollution, drought, floods, the optimum use of a well field, artificial supply, interaction between civil engineering work and aquifers. The user therefore wishes to obtain a suitable presentation of the situation, either complex (detailed hydrogeological map), or simple (map as an aid to decision-making), which can easily be brought up to date. The development of a thematic method of hydrogeological cartography will make it possible to propose, to the public authorities, decisive elements required in order to carry out a global and coherent policy for the groundwater management. Finally, this approach must allow to non-hydrogeologists to more easily understand the movement of groundwater. The paper presents the mapping of groundwater circulations recognized by tracing in karstic medium. The use of artificial tracers is a well established method for investigation of karstic aquifers. The majority of the tracer experiments (artificial and biological tracers) are applied to specify the watercatchment boundaries: the relation between a sinkhole and an outlet, diffluent phenomens, transit time, etc. Recently tracing experiments have become a well known tool for transport simulations of miscible pollutants with groundwater. An application to obtain an information system has been developed by the use of ArcInfo coupled with Oracle by storing and querying of the available data just up to level with a continuously updated map of groundwater circulations recognized by tracing. The project offers the tools adapted in the field of groundwater management and protection.




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