Pump and Treat
- Groundwater is extracted using 6 wells, located on site, at an average total pumping rate of 60 gpm
- Extracted groundwater is treated with chemical treatment (addition of ferric chloride, lime slurry, phosphoric and sulfuric acids, and ammonium sulfate), clarification, aeration, filtration, and carbon adsorption
- Treated groundwater is reinjected through infiltration basins
- ROD Date: 9/30/86
|Point of Contact:|
Chet Janowski, RPM
U.S. EPA Region 1
John F. Kennedy Federal Building
One Congress Street
Boston, MA 02203
|State Point of Contact:|
Volatiles - nonhalogenated (BTEX); semivolatiles - nonhalogenated; polycyclic aromatic hydrocarbons (PAHs, acenaphthene, naphthalene, 2,4- dimethylphenol); organic pesticides/herbicides (dieldrin, chlordane); heavy metals (lead); and nonmetallic elements (arsenic)
- Maximum initial concentrations measured at the site were VOCs (>1,000 mcg/L), SVOCs (>10,000 mcg/L); concentrations of specific contaminants not provided
Surface impoundment/lagoon, hazardous materials storage, discharge to septic system, discharge to wetlands
Type/Quantity of Media Treated:
- 80 million gallons treated as of February 1997
- LNAPL observed in several monitoring wells on site
- Groundwater is found at 10-15 ft bgs
- Extraction wells are located in 3 aquifers, which are influenced by a nearby surface water
- Hydraulic conductivity ranges from 0.5 to 45 ft/day
Purpose/Significance of Application:
Groundwater contaminated with a wide variety of contaminants; relatively expensive remediation, with high capital costs for treatment system.
Regulatory Requirements/Cleanup Goals:
- Cleanup goals were established to be maximum contaminant levels (MCLs) as defined by the primary drinking water standards and the state of Massachusetts drinking waster quality criteria. Cleanup goals were established for benzene (5 mcg/L), toluene (2,000 mcg/L), ethylbenzene (680 mcg/L), xylene (440 mcg/L), 2,4-dimethyl phenol (2.12 mcg/L), naphthalene (0.62 mcg/L), acenaphthene (0.52 mcg/L), dieldrin (0.000071 mcg/L), chlordane (0.00046 mcg/L), arsenic (0.05 mcg/L), and lead (0.05 mcg/L).
- Additional goals were to remediate the contaminated aquifer within a reasonable time to prevent present or future impacts to groundwater drinking water supplies, and to protect the Cochato River from future contaminant migration by establishing hydraulic containment of the plume.
During the first two years of operation, the pump and treat system reduced average VOC and SVOC concentrations. From 1994 to 1995, average VOC concentrations decreased by 16% and average SVOC concentrations by 48%. However, contaminant concentrations in some individual wells did not decline over this period and concentrations have not been reduced to below treatment goals. As of December 1995, 2,100 pounds of organic contaminants have been removed from the groundwater. -
Contaminants have been detected in down-gradient monitoring wells and plume containment has not been achieved. A 1995 study made recommendations for achieving plume containment.
- Actual costs for pump and treat were $22,726,000 ($14,958,000 in capital and $7,768,000 in O&M), which correspond to $284 per 1,000 gallons of groundwater extracted and $10,822 per pound of contaminant removed.
- Operating costs are relatively high because of the need to analyze for a large number of contaminants and the need for an operator to be on-site 24 hours per day.
Baird and McGuire Inc. conducted chemical mixing operations at this site from 1912 to 1983. Contamination of an on-site public drinking water well was first detected in 1982 by the town of Holbrook. Also in 1982, a citizen complaint of an oily substance in the Conchato River, which runs along the eastern boundary of the site led to an inspection by DEQE. This inspection revealed that a tank farm was not lined or diked, sewage waste, process waste, and surface water runoff were collected in an open cesspool; and a black oily substance was being discharged to on-site wetlands. During emergency removal actions by EPA in 1983 and 1985, a plume of VOCs and SVOCs was identified in the groundwater beneath the site. The site was added to the NPL in October 1982 and a ROD was signed in September 1986.
The groundwater extraction system consists of six wells placed in the part of the plume where the highest levels of contamination were detected. Groundwater treatment includes equalization and removal of free floating product, chemical treatment (with ferric chloride and lime in one stage, and phosphoric and sulfuric acids and ammonium sulfate in a second stage), flocculation/clarification, aeration, pressure filtration, and carbon adsorption, prior to discharge to infiltration basins. Above-ground biological treatment (using activated sludge) was included in the original design for this site, but was found to be not necessary, and deleted from the treatment system. After three years of operation, the system has not met the cleanup goals established for this site. In addition, the report discusses the impacts of having concurrent groundwater and soil remediation activities at this site.
Also view/download http://www.clu-in.org/download/remed/rse/baird_and_mcguire.pdf