1. A Risk Assessment of Closed Landfills, Groundwater Quality, and Possible Connections to Environmental Justice Bexar County, Texas 2000-2004 LIGERS – George Strebel, Liz Duca, James Graham, Colin Barth, Jake Duffy, and Gordon Young FFLAPES (Faults, Flood Plain, Aquifer, Permeability, Erosion, Slope) FFLAPS was developed as method to conduct a risk assessment of closed landfills over groundwater in regards to possible contamination. A ranking system can be created by looking at the specific features: soil characteristics, aquifer zones, fault areas, flood plain, permeability, erosion, slope. See Figure 4. This ranking system can then be put into a GIS and applied to rank closed landfills to investigate for instances of environmental injustice. FFLAPES PARAMETERS F – Faults FL – Flood Plain A – Aquifer P – Permeability E - Erosion S - Slope From these parameters a FFLAPES risk assessment rating can be obtained. The higher the value for the FFLAPES rating, the greater the risk is of the closed landfill to the aquifer. FFLAPS Rating = F r F+FL r FL+A r A w +P r P w +E r E+S r S r=rank w=weight Figure 4 Figure 5 Closed Landfills In 1993 the Texas Legislature passed House Bill 2537, which required the Regional Councils of Governments to include an inventory of closed municipal solid waste landfills in their regional plans for solid wasted management. This effort resulted in the location of approximately 4,200 closed and abandoned municipal waste landfills throughout Texas. In 1998, the Council of Government was mandated by the Texas Natural Resources Conservation Commission (TNRCC) to inventory the closed and abandoned landfills in each county within their region. Bexar County falls under the jurisdiction of the Alamo Area Council of Governments (AACOG) which was responsible for gathering historical information, affidavits, and any other relevant data to produce the inventory. Using the inventoried landfill sites provided by House Bill 2537 and through further research regarding landfill existence, AACOG visited appraisal districts, county engineers, commissioners, judges, law enforcement authorities and the general public to create the AACOG Inventory of Closed or Abandoned Landfills. The Landfill locations used in this study are a result of AACOG’s hard work. Figure 2 Figure 3 Abstract The purpose of this study is to perform a risk assessment on closed landfills in Bexar County in relation to the county’s primary drinking water source: the Edwards Aquifer. We identified the high risk closed landfill areas and explored the relationships of these areas to low income high minority (LIHM) groups to investigate possible environmental injustices. See Figure 1 for the scope of our study area. Figure 1 Environmental Justice Environmental Injustice exists if - As levels of environmental harm increase, 1. An over-representation of ethnic minorities (positive relationship) 2. A decrease in social class (negative relationship) 3. A decrease in political mobilization (negative relationship) -adapted from Lester, et al (2001) Most environmental justice studies have investigated the issue with conveniently available Census Block, Block Group and Tract demographic data. Some have utilized geographic shapefile polygons to investigate proximity to potential environmental hazards. One of the primary reasons these studies fail to accurately depict "true proximity" to potential environmental hazard is because Census Block Group boundaries fail to represent the residential community or its relation to a potential environmental hazard. Indeed, some residential areas may fall far outside of a "proximity buffer", but because the community falls within a particular areal unit of aggregation (Census Block, Tract, etc.) the community is considered within the buffer. See Figure 6, Figure 7, Figure 8 and Figure 9. Census data for our study have been aggregated to the Bexar County residential parcels. See Figure 10, and Figure 11. Adopting a dasymetric perspective on the study of environmental justice (Mennis, 2002), we believe that this is a more accurate depiction of the residential communities and the aggregated census data that represents their respective community. See Figure 12, Figure 13 and Figure 14. Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Edwards Aquifer Figure 15 Figure 16 The Edwards Aquifer is composed of four zones: the contributing, the recharge, the transition, and the artesian.See Figure 15. It was necessary to rank each zone of the Edwards Aquifer based on its susceptibility to the hazards posed by a high risk landfill.See Figure 16. The outcrop of the Edwards, the recharge zone, was ranked as having the highest vulnerability to contamination. This is due to the very porous nature of the surface of the recharge zone, making it susceptible to contaminants that could make their way into surface water and then subsequently permeate the surface and enter the water table. The transition zone was ranked the second highest, due to its close proximity to the very sensitive recharge zone. The contributing zone of the Edwards aquifer is the area in which groundwater makes its way into the streams and waterways which eventually flow into the recharge zone, for this reason it was ranked third. The least susceptible zone of the Edwards aquifer is the artesian zone, the area where most drinking water is pumped from. The artesian zone is lined by a very thick and impermeable clay and limestone structure, which makes surface contamination and recharge very difficult, earning it the lowest rank. Conclusion This study is necessary to examine the relationship between the county’s landfills and groundwater supply. We explored issues regarding environmental justice to determine if the socioeconomically deprived are disproportionately affected by “high-risk” conditions. To conduct a risk assessment of closed landfills on the underground water supply, a potential risk model was created (FFLAPES). This model consists of six different parameters that are meant to measure the potential impact closed landfills have on the Edwards Aquifer. Zonal Statistics were then used to overlay the ranked closed landfill polygons on the FFLAPES Model to determine the summary statistics for each landfill area. The average value for each closed landfill was then used as a Total Rank number to rank the closed landfills from low risk potential to high risk potential. Twenty three high risk potential closed landfills were found on the Edwards Aquifer zone, along with seventeen public water system intakes located within 500 feet of eight closed landfills. These closed landfills and public water system intakes should be further investigated. In the secondary portion of our analysis, these regions will then be compared to ethnic minority populations and low income communities to examine any possible cases of environmental injustice. The closed landfill risk assessment will also be valuable for future studies involving possible environmental injustices, landfill maintenance and clean up, as well as future growth/development decisions for properties in close proximity to closed landfill areas. GEO 4427- Dr.Yongmei Lu and Nikki Williams Demographic Variable Inside One Mile Buffer Area (%) Bexar County (%) Percent Difference Ethnic Hispanic42.754.3-11.6 Ethnic Black77.7-.7 Low Income1116.86-5.86 Demographic Variable Inside One Mile Buffer Area (%) Bexar County (%) Percent Difference Ethnic Hispanic2454.3-30.3 Ethnic Black2.77.7-5.0 Low Income416.86-12.86 Table 2: Results for “High Risk” Landfill Subset (total = 23) Table 2: Results for Landfill (total = 313)