Pump and Treat and Air Sparging of Contaminated Groundwater at the Gold Coast Superfund Site, Miami, Florida

Site Name:

Gold Coast Superfund Site


Miami, Florida

Period of

7/90 - 3/94: pump and treat
11/94 - 2/95: air sparging


Full-scale cleanup


- Construction: Simmons Consulting, Inc.
- Treatment System Vendor: Lantec
- Operations: Simmons Consulting, Inc.
and The Balijet Corp.,
Edward E. Clark Engineers-Scientists, Inc.

Pump and Treat and Air Sparging
- Groundwater was extracted using five wells, located on site, at an average total pumping rate of 44 gpm
- Extracted groundwater was treated with air stripping and reinjected into the aquifer through three injection wells
- Groundwater was sparged with a portable sparger and contaminants were allowed to volatilize

Cleanup Authority:
CERCLA Remedial
- ROD Date: 9/11/87

EPA Point of Contact:
Brad Jackson, RPM
U.S. EPA Region 4
3456 Courtland Street, N.E.
Atlanta, GA 30365
(404) 562-8975
State Point of Contact:
Marvin Collins
Florida Department of
Environmental Protection (FDEP)
Tallahassee, FL
(850) 488-0190

Chlorinated solvents and volatiles - nonhalogenated (toluene)
- Maximum initial concentrations were methylene chloride (100 µg/L), 1,1-DCA (2,000 µg/L), trans-1,2-DCE (3,000 µg/L), TCE (48,000 µg/L), PCE (100,000 µg/L), and toluene (545 µg/L)

Waste Source:
Direct discharge of solvent reclamation blowdown to soil; improper storage of waste

Type/Quantity of Media Treated:
- 80 million gallons treated as of February 1996
- DNAPL observed in groundwater on site
- Groundwater is found at 5 ft bgs
- Extraction wells are located in one aquifer and are influenced by a nearby surface water
- Hydraulic conductivity was reported as 1,000 ft/day

Purpose/Significance of Application:
Met goals within four years of operation; included pump and treat and air sparging

Regulatory Requirements/Cleanup Goals:
- The remedial goal was to reduce contaminant concentrations throughout the aquifer to levels below the maximum contaminant levels (MCLs) set by the FDEP, DERM, and primary drinking water standards.
- Remedial goals were identified for 1,1-DCA (5 µg/L), trans-1,2-DCE (70 µg/L), methylene chloride (5 µg/L), PCE (0.7 µg/L), TCE (3 µg/L), and toluene (340 µg/L).
- Effluent from the treatment system was required to meet the remedial goals prior to re-injection.
- A secondary goal was identified to create an inward gradient toward the site to contain the plume.

Groundwater monitoring results indicate that contaminant concentrations have been reduced below treatment goals; from 1991 to 1994, 1,961 lbs of TCE and PCE were removed from the groundwater.
Optimization efforts were used to focus cleanup on the problem areas at the site; excavation of soil suspected to contain DNAPLs and groundwater sparging were performed to complete cleanup of problem areas.
Performance monitoring results indicate that effluent requirements have been met throughout the operation of the treatment system.
No contaminants were detected in downgradient monitoring wells during remedial operations, indicating that the plume was contained throughout the remedial action

Cost Factors:
- Actual cost data were provided by the responsible parties for this application.
- Costs for pump and treat were $694,325 ($249,005 in capital and $445,320 in O&M), which correspond to $9 per 1,000 gallons of groundwater extracted and $354 per pound of contaminant removed.

Gold Coast Oil Corporation operated as a spent oil and solvent recovery facility from 1970 to 1982. Recovery operations at the 2-acre site included distillation of lacquer thinner and mineral spirits; blowdown from these operations was discharged directly onto the soil. In 1980, the FDEP detected soil and groundwater contamination in on-site soil (heavy metals and organics) and an off-site groundwater well (VOCs). The site was placed on the NPL in September 1983 and a ROD was signed in September 1987.

Five extraction wells were constructed in the Biscayne Aquifer at the site. Three wells were installed to a depth of 15 ft, with a design yield of 10 gpm; two wells were installed to a depth of 30 ft, with a design yield of 35 gpm. Extracted groundwater was treated using two air stripping towers in series, with each tower 36 ft high, 3 ft diameter, and packed to 26 ft with IMPAC, a material that enhances stripping of VOCs from water. Treated groundwater was re-injected into the aquifer through three injection wells.

Cleanup standards were met at this site within approximately four years of operation. Cleanup was achieved after excavation of soil suspected to contain DNAPLs and groundwater sparging were performed.