Site Summary
Used for irrigation purposes.
2) Squeaky Clay “semi-confining” layer
3) Floridan Aquifer - Limestone - depth to aquifer ranges from 17- 37 feet
below surface. Floridan is primary source of potable water. 4) Ground water flows to the southwest, into the Anclote River
C Approximately 300,000 cubic yards (cy) of radiologically and chemically contaminated soils, pond sediments, and slag materials are present at the Stauffer Site. 300,000 cy is equivalent to an area of 30 football fields piled 6 feet high. Soils also contain elemental phosphorus, which spontaneously ignites when in contact with air.
C Elemental Phosphorous was produced by mining phosphate ore, heating the ore in an electric arc furnace, removing the elemental phosphorous in its gaseous state, and returning it a liquid state in an on-site condenser. The ore was mined by others offsite.
| C | Remaining phosphorous sludge was re-heated to recover remaining phosphorous. |
|---|---|
| C | Process wastes were disposed of in on-site, unlined lagoons. |
| C | By-products included slag, which contained radium-226, arsenic, beryllium, and other |
| heavy metals. The slag was processed and sold as aggregate from the slag processing area | |
| in the northern part of the site. |
C The site was proposed for the National Priorities List in 1992 and was listed in 1994.
C Stauffer entered into a voluntary Administrative Order on Consent to conduct the Remedial Investigation/Feasibility Study (RI/FS) in 1992. They completed it in 1996.
C Stauffer conducted a removal action in 1997 to remove crude phosphorous material from above ground storage tanks in the clarifier.
C EPA signed the Record of Decision addressing source materials in July 1998. Ground water, while evaluated as part of this RI/FS, will be addressed under a separate OU.
C The EPA and Stauffer have signed the Consent Decree (CD). The CD is currently being routed through the Department of Justice.
The major components of the remedy include the following. The estimated cost is $9M.
C Limited excavation of radiologically and chemically contaminated soils which exceed residential cleanup standards, consolidation and capping materials on-site.
C Institutional controls including deed restrictions, land use ordinances, physical barriers, and water supply well restrictions. These controls will prohibit residential use.
C In-situ solidification/stabilization of contaminated materials below the water table, in the consolidation areas only. Note: Capped soils above the water table will not be solidified
Note: EPA is proceeding with the remedy selected; however, the ROD does not cast the remedy in stone. If during the design or construction of the remedy, EPA finds that it is not protective of human health and the environment, we will revisit the remedy and make the necessary changes.
Contaminants of Concern at the Site, Maximum Detected Concentrations, and Cleanup Standards
| Max Detected | ||
|---|---|---|
| Contaminant | Concentration | Cleanup Standard |
| Arsenic | 127 ppm | 21.1 ppm |
| Antimony | 32.2 ppm | 28.1 ppm |
| Beryllium | 1.6 ppm | 120 ppm |
| Elemental Phosphorous | 0.854 ppm | 1.4 ppm |
| Thallium | 13.4 ppm | 1.4 ppm |
| Radium-226 | 73.8 pCi/g | 5 pCi/g(all depths) |
| Radium-226 Dose | 140 uR/hr | 20 uR/hr |
C Estimated Volume of Contaminated Material to be shipped off is at least 300,000 cubic yards.
C Local landfills may not accept these materials due to large volumes, radiation, and phosphorous in the waste. Estimated cost to ship to Envirocare in Utah = $200,000,000, based on the RI/FS.
C Short term impacts would be more severe for off-site shipping. Adverse effects would include transporting hazardous waste through narrow streets, large volume truck traffic to haul clean fill to the site, dust creation, traffic nuisances and hazards. Truck volume would exceed 15,000 trucks per year.
C Leaving waste on site minimizes movement; in-situ remedy reduces amount of excavated waste to 120,000 cubic yards.
C On-site consolidation is compatible with soils, slag, and sediments
C Cap over consolidated materials will provide impermeable cover to ensure that rain water does not transport wastes into the ground water. On-site soil cover will provide necessary shielding from radiation. On-site cover will allow the use of vegetation to prevent erosion.
CSelected remedy provides short and long term protection of human health and the environment, prevents future residential land use, yet allows future commercial and/or recreational use of the site.
C EPA considers the cleanup standards to be protective of human health and the environment.
C The anticipated future land use is commercial/industrial. However, the cleanup standards assume future residential land use. The more stringent requirements were put in place to address community concerns. The Stauffer Management Company currently is considering the construction of a golf course and marina at the site.
C Materials to be solidified/stabilized will be within the surficial aquifer. Quality control and long term effectiveness are primary concerns. EPA plans to address these issues during design.
C Slight vertical gradient between the Surficial and Floridan Aquifer. Direction of gradient dependent on location within the site.
C More characterization of Floridan Aquifer required. Current data shows little impact.
EPA is sensitive to the concerns of the Tarpon Springs community regarding this remedy and will address them as we proceed through the design of the remedy. EPA has worked closely with the community, holding many public hearings from 1993 to the present. In 1999 alone, EPA made a site visit to each individual home that EPA sampled to discuss results of the offsite sampling effort. This was followed with a public meeting to formally announce the results of offsite sampling to the community at large. In addition, the EPA will invite the community to assist in the review
In addition, the EPA will invite the community to assist in the review and comment on the design submissions.
1. Hydrogeologic Assessment - 1987 - Seaburn and Robertson, Inc.
a. Study the hydrogeologic characteristics of the surficial and Floridan aquifers at the site.
2. Final Expanded Site Investigation - 1989 - NUS, Inc.
a. Evaluate surface soils, ground water, subsurface soils, ground water in surficial and Floridan aquifers, surface water in Anclote River.
3. Interim Final Listing Site Inspection - 1991 - NUS, Inc.
a. Evaluate surface soils at school, re-sample ground water, collect sediment samples from the Anclote River.
4. Radiological Studies - 1990 - PBS&J.
a. Conducted external gamma radiation surveys of roadways, ponds
5. Site Sampling Program - 1989 and 1990 - Weston.
a. Soil and pond sampling.
6. Environmental Sampling Program - 1990 - Weston.
a. Characterize soil and disposal pond materials.
7. Sediment Sampling Program - 1991 - Weston.
a. Collected 13 sediment samples on from the Anclote River.
8. Elemental Phosphorous Borings Program - 1991 - Weston
a. Collected samples from 47 phosphorous soil borings.
9. Treatability Study - Bench Scale Oxidation Study - 1991 - Weston
a. Evaluate performance of various oxidizers in treating elemental phosphorous.
10. Chemical Oxidation of Phosphorous Study
a. Determine feasibility of oxidizing elemental phosphorous clarifier using Nitric Acid
11. Phosphorous Recovery, Bench Scale and Treatability Testing Studies
a. Determine if elemental phosphorous can be recovered, separated from other materials and effectively treated on-site. Excavation and treatment difficult.
12. Treatability Study - Solidification/Stabilization Study of Pond Wastes - 1991 - Weston
a. Evaluated various stabilization mixes to see which would meet strength and economic feasibility requirements
13. Soil Depth Cover Study - 1994 - Weston
a. Recommended 24" soil cover to minimize gamma radiation dose
14. Soil/Slag Leachability Study - 1997 - Parsons Engineering
a. Determined that contaminants leaching from soil and slag in the slag field are minimal.
15. Asbestos Sampling - On-site soil and air - July 1998 - Parsons Engineering
16. Final Remedial Investigation Report - December 1993 - Weston
a. Evaluated all media.
17. 1994 Elemental Phosphorous Soil and Ground Water Sampling Program
a. Distinguish between elemental and total phosphorous.
18. Background soil sampling for Arsenic and Beryllium - 1999
a. Background levels below State of Florida Cleanup Levels
19. On-going surficial ground water monitoring program
• Approximately 53 surface soil samples were collected on-site. The table below provides a summary of the results. With the exception of slag and one arsenic sample, the sample locations exceeding the cleanup standards were in the western and southern parts of the site. All slag roads, the slag processing area, and the pond areas, exceed their respective cleanup standards.
Max Detected Contaminant Concentration Arsenic 127 ppm Antimony 32.2 ppm Beryllium 1.6 ppm Elemental Phosphorous 0.854 ppm Thallium 13.4 ppm Radium-226 73.8 pCi/g Radium-226 Dose 140 uR/hr
No. Samples Cleanup Standard Exceeding Standard
21.1 3
28.1 1 120 0
1.4 Pond Material Only
1.4 4 5 (all depths) All Slag/Roads 20 uR/hr All Slag/Roads
• 28 samples have been collected on the site. The table below provides a summary of the results. Elemental phosphorous has not been found in any locations other than the pond material.
Max Detected Contaminant Concentration Arsenic 46.6 ppm Antimony 22.6 ppm Beryllium 0.28 ppm Elemental Phosphorous 0.854 ppm Thallium 4.3 ppm Radium-226 73.8 pCi/g
Radium-226 Dose 140 uR/hr
No. Samples Cleanup Standard Exceeding Standard
21.1 1
28.1 0 120 0
1.4 Pond Material
1.4 2 5 (all depths) All Slag/Roads
and some ponds 20 uR/hr All Slag/Roads
Contaminant Arsenic Antimony BerylliumElemental Phosphorous Thallium Radium-226 Radium-226 Dose
Max Detected Concentration Cleanup Standard
| 205 ppm | 21.1 ppm |
| 52.0 ppm | 28.1 ppm |
| 2.0ppm | 120 ppm |
| 0.854 ppm | 1.4 ppm |
| 37.0 ppm | 1.4 ppm |
| 34.0 pCi/g | 5 pCi/g(all depths) |
| 35 uR/hr | 20 uR/hr |
iron. There were no exceedances of MCLs for site related contaminants. There were elevated levels of radon detected.
• 13 surface soil samples were collected at the school; all samples collected were below the residential soil cleanup criteria.
• Air monitoring results obtained during the remedial investigation indicated that airborne volatile organic compounds are not a problem at the site unless construction activities are in progress. In this case, the potential for ignition of elemental phosphorous may cause a problem. This will be taken into consideration during the design.
• Petitioned Health Consultation - Holiday Utilities - Tarpon Springs, Florida -Currently out for public comment.
A. The ATSDR is preparing a Petitioned Health Assessment for the Holiday Utilities municipal water supply in Tarpon; it is currently out for public comment. The ATSDR has concluded that, based upon 1989 sampling results, the contaminants present do not pose a health hazard. The Florida Department of Environmental Protection will continue to monitor the site.
A. ATSDR evaluated potential health threat to students and staff due to chemicals and radionuclides in soils and the air at the Gulfside Elementary School. They concluded that illnesses are unlikely in adults, pica children, and non-pica children due to exposure from contaminants in soil, aggregate, and air at the school.
• Public Health Assessment - Stauffer Chemical Company Superfund Site, Tarpon Springs March 1993
A. The ATSDR conducted a health assessment to determine if the site posed a public health hazard. They determined that the site is a public health hazard and recommended characterization of the site and surrounding residential area