Ex Situ Air Stripping and GAC Treatment of Drinking Water at the Rockaway Township Site, Rockaway, New Jersey

Site Name:

Rockaway, NJ

Location:

Rockaway Township, New Jersey

Period of
Operation:

1980 to present

Cleanup
Type:

Full scale

Vendor:

Fenton Purcell
Lee T. Purcell Associates
60 Hamilton Street
Paterson, NJ 07505
Telephone: (973) 278-5700
Fax: (973) 278-8410
E-mail: purclfen@galaxy.net

Technology:
Air stripping followed by granular activated carbon (GAC)
- GAC system - two downflow pressure contactors (20 feet high and 10 feet in diameter and containing 20,000 pounds of Calgon F-300 carbon) operated in parallel; rated capacity of 1,000 gpm
- Air Stripping (original) - aluminum, countercurrent packed column (35 feet high and 9 feet in diameter, packed with 1,640 cubic feet of 3-inch polyethylene telerettes); design capacity of 1,400 gpm; design air flow rate was 37,500 cubic feet per minute (cfm) with an air-to-water ratio of 200:1
- Air Stripping (1993) - the corroded aluminum column was replaced with a same size fiberglass air stripper. Because MTBE was no longer observed in the supply wells, the fiberglass air stripper was redesigned to focus on the removal of TCE and DIPE, rather than MTBE. The new design uses a 30 hp blower and 20,000 cfm of air flow

Cleanup Authority:
State
NJDEP Administrative Consent Order

State Contact:
Vincent Monaco
NJ Department of Environmental Protection (NJDEP)
Bureau of Safe Drinking Water
P.O. Box 426
401 East State Street, 3rd Floor
Trenton, NJ 08625-0426
Telephone: (609) 292-5550
Fax: (609) 292-1654
Site Contact:
Robert Sheard
Rockaway Township
65 Mount Hope Road
Rockaway, NJ 07866
Telephone: (973) 983-2876
Fax: (973) 625-7764
E-mail: rsds321@aol.com

Contaminants:
MTBE, diisopropyl ether (DIPE), TCE, other VOCs, TBA
- Concentrations of MTBE in the supply wells ranged from 25 to 40 ug/L; DIPE concentrations ranged from 70 to 100 ug/L

Waste Source:
Leaks from underground storage tanks from a gasoline service station

Type/Quantity of Media Treated:
Drinking Water

Purpose/Significance of Application:
Use of air stripping and GAC to treat MTBE in drinking water

Regulatory Requirements/Cleanup Goals:
No specific treatment goals for MTBE were provided.

Results:
GAC-only system (October 1980 to February 1982) - initially, effluent concentrations of contaminants were reduced to below detectable limits; GAC break through in January 1981 resulted in increases in MTBE and DIPE concentrations; carbon was replaced in March 1981; subsequent carbon replacement was required once every four to six weeks, until aeration was added as a pretreatment step
- Air Stripping and GAC system (February 1982 to ongoing) - following addition of the air stripper, MTBE and DIPE concentrations were reduced, falling to 1 ug/L by December 1992. In 1993, MTBE was no longer detected, and the system was reconfigured (described above) to focus on treatment of TCE and DIPE. As of July 2000, no MTBE or TBA found in the supply wells; system continuing to operate to treat TCE and other VOCs

Cost Factors:
Air Stripping - capital cost - $375,000, including the column, packing media, blowers, piping, controls, site work, and booster pumps; annual operating cost (primarily cost for power) - $100,000, based on a cost for electricity of $0.09/kW-hr
GAC - capital cost - $200,000, including the contactors, GAC, piping, site work, and the building; annual operating cost (primarily carbon replacement) - $200,000 ($0.52/1,000 gallons of water treated)

Description:
The Rockaway Township, located in northern New Jersey, owns and operates a water supply system that provides drinking water to about half of the township's population. The system supplies groundwater from two wells (wells 6 and 7). The supply wells were found to be contaminated with MTBE and DIPE at levels ranging from 25 to 40 ug/L, and 70 to 100 ug/L, respectively. TCE and other VOCs were also found in the supply wells. The source of the contamination was identified as a gasoline service station (Shell Oil). To treat the drinking water from the supply wells, a GAC system was initially installed in 1980. However, during operation, breakthrough of MTBE and DIPE occurred relatively quickly and air stripping was added in Ferbruary 1982 to help extend the life of the carbon.

By 1993, MTBE was no longer detected in the supply wells. However, in 1997, a Shell Oil gasoline service station developed a leak, with MTBE entering the Rockaway Township drinking water supply wells. MTBE levels in the supply wells were found at concentrations ranging from 1 - 8 ug/L. Shell Oil installed an off site treatment plant which contained the MTBE to within minimal levels. In addition, TBA was also detected in the supply wells. According to the Rockaway Township, as of July 2000, no MTBE or TBA were being found in the supply wells. The air stripper/GAC treatment system is continuing to remove TCE and other VOCs (1,1-DCE, 1,1-DCA) from the supply wells.