Description
Historical activity that resulted
in contamination.
| PCE drycleaning operations were conducted at this site from 1975 - 1984. As part of a voluntary cleanup, an air sparge/soil vapor extraction remedial system began operating at the site in October of 2003. The system consisted of four air sparge wells screened 35-40 ft BLS powered by a rotary vane compressor with a 10 HP blower. The air sparge wells were installed in the parking lot in front of (down gradient) the former location of the drycleaning facility. The SVE system consisted of four lateral vapor extraction wells with 10-foot screens installed 3 feet BLS. The vapor extraction wells were installed in the parking lot in front of the building that formerly housed the drycleaning operation. The SVE system was powered by a 10 HP blower with off gas treated via two 55-gallon G.A.C. drums. The air sparge/SVE system was shut down on September 16, 2005 for transfer to the Florida Drycleaning Solvent Cleanup Program. The SVE system was re-started on January 9, 2006.
Subsequent contamination assessment work conducted by the Florida Drycleaning Solvent Cleanup Program in early 2006 found contaminated soil under and in close proximity to the bay that formerly housed the drycleaning operation.
The site is located in a shopping center in a mixed retail/commercial setting. Remediation Status: In active remediation |
Contaminants
Contaminants present and the highest amount
detected in both soil and groundwater.
| Contaminant |
Media |
Concentration (ppb) |
Nondetect |
| cis-1,2-Dichloroethene |
groundwater |
323 ppb |
|
| Tetrachloroethene (PCE) |
groundwater |
836 ppb |
|
| Tetrachloroethene (PCE) |
soil |
476 ppb |
|
| Trichloroethene (TCE) |
groundwater |
80.4 ppb |
|
| Vinyl Chloride |
groundwater |
2.39 ppb |
|
Site Hydrology
| Deepest Significant
Groundwater Contamination: |
|
30ft bgs |
| Plume Size: |
|
Plume Length: 550ft
Plume Width: 130ft
Plume Thickness: 25ft |
| Average Depth
to Groundwater: |
|
7.3ft |
Lithology and Subsurface Geology
|
|
silty, fine-grained sand
Depth: 0-30ft bgs
30ft thick
Conductivity: 4.32ft/day
Gradient: 0.002ft/ft
|
|
|
sandy silt with coquina
Depth: 30-40ft bgs
10ft thick
|
|
|
fine-grained sand with shells
Depth: 40-46ft bgs
6ft thick
|
Pathways and DNAPL Presence
 Groundwater
 Sediments
Soil
DNAPL Present
|
Vapor Intrusion Pathway
Has the potential for vapor intrusion (VI) been evaluated? |
|
No
|
Has a vapor mitigation system been installed? |
|
Yes |
Type of Vapor Mitigation System(s): |
|
Soil Vapor Extraction
|
Remediation Scenario
Cleanup
Goals: |
|
Soil: PCE = 30 ug/kg (leachability)
Groundwater: PCE = 3 ug/L, TCE = 3 ug/L, cis 1,2-DCE = 70 ug/L, vinyl chloride = 1 ug/L
|
Remedy Level: |
|
Full Scale Remedy |
Technologies
In Situ Air Sparging |
|
Why the technology was selected:
Air sparge was selected because dissolved phase VOCs are present in permeable sediments at relatively shallow depths (< 20 ft BLS).
Date implemented:
Modified air sparge/SVE sytem startup: October 15, 2008
Final remediation design:
Modified air sparge/SVE system: The sparge system consists of nine (9) air sparge wells screened 18-20 ft BLS. Two of the sparge wells are located beneath the floor slab of the bay that is adjacent to the former location of the drycleaning operation. Two (2)sparge wells are located immediately outside the rear door of the bay that formerly housed the drycleanign operaitons. The other five (5) sparge wells are located immediately down gradient of the bay that formerly housed the drycleaning operation. The sparge system is powered by a 7.5 HP rotary claw motor. The SVE system consists of eleven (11) vapor extraction wells. Nine of these are vertical vapor extraction wells two of which are installed beneath the floor slab of the adjacent bay and two of which are installed directly behind the bay that formerly housed the drycleaning operaton. The other five vertical vapor extraction wells are installed due north of the former location of the drycleaning facility. Two horizontal vapor extraction wells with screen lengths of 10 and 5 feet were installed beneath the bay adjacent to the former location of the drycleaner and in a drive through east of the adjacent bay. The system is powered by a 10 HP Rotron blower. Off gas is treated via a 55 gallon G.A.C. vessel.
Results to date:
From June 14-18, 2010, the SVE system was shut down for modifications. Three additional lateral vapor extraction wells were installed under the floor slab of the bay adjacent to the former location of the drycleaning facility.
Groundwater monitoring conducted in June of 2011 found that the highest contaminant concentrations in groundwater were 31.2 ug/l PCE and 4.61 ug/l TCE and that contaminant concentraitons in groundwater samples collected from the monitor wells located immediately down gradient of the air sparge/SVE system and the facility were below MCLs. This marks the first monitoring event that this has occurred. If contaminant concentrations in these wells remain below MCLs at the next monitoring event, the recommendation will be to shut down the sparge system and pulse the SVE system. PCE concentrations in SVE system air influent samples have dropped two orders of magnitude since the revised SVE system began operating.
Cost to Design and Implement:
All technologies: Design: $42,000
Implementation: $294,900
|
In Situ Soil Vapor Extraction |
|
Why the technology was selected:
SVE was selected because it is an effective technology for removing VOCs from permeable unsaturated sediments.
Date implemented:
Modified air sparge/SVE sytem startup: October 15, 2008
Final remediation design:
Modified air sparge/SVE system: The sparge system consists of nine (9) air sparge wells screened 18-20 ft BLS. Two of the sparge wells are located beneath the floor slab of the bay that is adjacent to the former location of the drycleaning operation. Two (2)sparge wells are located immediately outside the rear door of the bay that formerly housed the drycleanign operaitons. The other five (5) sparge wells are located immediately down gradient of the bay that formerly housed the drycleaning operation. The sparge system is powered by a 7.5 HP rotary claw motor. The SVE system consists of eleven (11) vapor extraction wells. Nine of these are vertical vapor extraction wells two of which are installed beneath the floor slab of the adjacent bay and two of which are installed directly behind the bay that formerly housed the drycleaning operaton. The other five vertical vapor extraction wells are installed due north of the former location of the drycleaning facility. Two horizontal vapor extraction wells with screen lengths of 10 and 5 feet were installed beneath the bay adjacent to the former location of the drycleaner and in a drive through east of the adjacent bay. The system is powered by a 10 HP Rotron blower. Off gas is treated via a 55 gallon G.A.C. vessel.
Results to date:
From June 14-18, 2010, the SVE system was shut down for modifications. Three additional lateral vapor extraction wells were installed under the floor slab of the bay adjacent to the former location of the drycleaning facility.
Groundwater monitoring conducted in June of 2011 found that the highest contaminant concentrations in groundwater were 31.2 ug/l PCE and 4.61 ug/l TCE and that contaminant concentraitons in groundwater samples collected from the monitor wells located immediately down gradient of the air sparge/SVE system and the facility were below MCLs. This marks the first monitoring event that this has occurred. If contaminant concentrations in these wells remain below MCLs at the next monitoring event, the recommendation will be to shut down the sparge system and pulse the SVE system. PCE concentrations in SVE system air influent samples have dropped two orders of magnitude since the revised SVE system began operating.
Cost to Design and Implement:
All technologies: Design: $42,000
Implementation: $294,900
|
Ex Situ Carbon Adsorption |
|
Date implemented:
Modified air sparge/SVE sytem startup: October 15, 2008
Final remediation design:
Modified air sparge/SVE system: The sparge system consists of nine (9) air sparge wells screened 18-20 ft BLS. Two of the sparge wells are located beneath the floor slab of the bay that is adjacent to the former location of the drycleaning operation. Two (2)sparge wells are located immediately outside the rear door of the bay that formerly housed the drycleanign operaitons. The other five (5) sparge wells are located immediately down gradient of the bay that formerly housed the drycleaning operation. The sparge system is powered by a 7.5 HP rotary claw motor. The SVE system consists of eleven (11) vapor extraction wells. Nine of these are vertical vapor extraction wells two of which are installed beneath the floor slab of the adjacent bay and two of which are installed directly behind the bay that formerly housed the drycleaning operaton. The other five vertical vapor extraction wells are installed due north of the former location of the drycleaning facility. Two horizontal vapor extraction wells with screen lengths of 10 and 5 feet were installed beneath the bay adjacent to the former location of the drycleaner and in a drive through east of the adjacent bay. The system is powered by a 10 HP Rotron blower. Off gas is treated via a 55 gallon G.A.C. vessel.
Results to date:
From June 14-18, 2010, the SVE system was shut down for modifications. Three additional lateral vapor extraction wells were installed under the floor slab of the bay adjacent to the former location of the drycleaning facility.
Groundwater monitoring conducted in June of 2011 found that the highest contaminant concentrations in groundwater were 31.2 ug/l PCE and 4.61 ug/l TCE and that contaminant concentraitons in groundwater samples collected from the monitor wells located immediately down gradient of the air sparge/SVE system and the facility were below MCLs. This marks the first monitoring event that this has occurred. If contaminant concentrations in these wells remain below MCLs at the next monitoring event, the recommendation will be to shut down the sparge system and pulse the SVE system. PCE concentrations in SVE system air influent samples have dropped two orders of magnitude since the revised SVE system began operating.
Cost to Design and Implement:
All technologies: Design: $42,000
Implementation: $294,900
|
Costs
Cost
for Assessment:
|
|
$87,000 |
Cost
for Operation and Maintenance:
|
|
$8,750/month |
Total
Costs for Cleanup:
|
|
|
Lessons Learned
1. Addtional assessment work found that the sparge wells for the original air sparge system were screened in a silt/coquina zone with a lower permeability than the overlying silty, fine-grained sands where the higher contaminant concentrations occurred.
2. The initial air sparge/SVE system was located hydraulically down gradient of the contaminant source area (soils beneath the floor slab of the former drycleaning facility). Subsequent soil sampling under and in close proximity to the bay that formerly housed the drycleaning operation found relatively high concentrations of contaminants in the unsaturated zone at the former facility location.
3. The bay that formerly housed the drycleaning operation has been occupied by an active business and access has been limited. However, access to the adjacent bay was obtained while it was unoccupied so that air sparge wells and vapor extraction wells could be installed.
|
Contacts
Aaron Cohen
Florida Dept. of Environmental Protection
Bureau of Waste Cleanup, MS 4500
2600 Blair Stone Road
Tallahassee, Florida 32399
850-245-8974
Aaron.Cohen@dep.state.fl.us
Bill Vogelsong, PG, Consultant
Arcadis U.S., Inc.
2081 Vista Parkway
West Palm Beach, Florida 33411
Phone: 9561) 697-7000
E-Mail: Wvolgelsong@arcadis-us.com
|
Site Specific References
Contamination Assessment Report: 2005
Remedial Action Plan Modification: 2007
Construction Completion Report:2008
Operation & Maintenance Reports: 2008-present
Groundwater Monitoring Reports: 2006 - present.
Groundwater Monitoring Reports: 2005-present.
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