Wells were placed throughout Crooked River Plantation to monitor contamination levels during remediation. Four phases of in-situ chemical oxidation at the source site and a booster of food-grade soy bean oil have brought contamination levels at the site close to drinking water standards. The USGS estimates that natural attenuation will remove the remaining contaminants long befor the plume reaches Crooked River Plantation. Photos by PH3 Salvador Chavez

Groundwater almost clean

By JO2 Jennifer Spinner
Periscope Staff

Groundwater contamination from the nearly 30-year-old ''Old Camden'' municipal landfill on what is now NSB Kings Bay is almost completely cleaned up, thanks to an innovative remediation treatment that marries scientific technology with the healing power of nature.

''Kings Bay is a well-known site in remediation technology,'' said Frank Chapelle, United States Geological Survey hydrologist. ''It is one of the only sites in the world where we have monitored the effects of in-situ oxidation for an extended period and can actually witness the contamination disappearing.''

The problem was serious. A plume of hazardous groundwater contamination, including vinyl chloride, was moving from the old landfill site toward Crooked River Plantation, a residential area located just outside of the base gates.

The initial pump-and-treat solution, state of the art at the time, was installed in 1993.

Crooked River Plantation resident Dick King stands by an irrigation well at his home. The Navy discovered a plume of hazardous contamination in groundwater moving from the "Old Camden County" landfill, which was located on what is now NSB Kings Bay, toward the subdivision. Extensive remediation and monitoring of the site have resulted in a 95% drop in contamination levels at the source. Photos by PH3 Salvador Chavez

Monitoring wells were dug in the neighborhood and Navy officials hoped for the best. As time went on, however, contaminant concentrations continued to increase in the test wells during the pump and treat solution.

The Navy sought a better approach.

''We spent $9.8 million between 1991 and 1997 and estimated it would take another $15 million to continue remediation using the pump and treat method,'' said Melinda Nessmith-Picard, Site 11 environmental engineer. ''Not only was it expensive, it wasn't working. We knew there had to be a better way.''

Navy officials approached the USGS in 1997 for help and, after determining the origination area of contamination, in-situ oxidation was selected as the best option for treatment.

''We found the exact source of the contamination to be an area about 40 by 40 feet,'' said Chapelle. ''Because the area was so small, in-situ chemical oxidation was the fastest, most cost-effective way to accomplish the Navy's goal of quick, efficient remediation.''

In-situ chemical oxidation attacks the problem at its source using a chemical injection of hydrogen peroxide and ferrous iron catalyst, known as Fenton's Reagent, combined with monitored natural attenuation; the earth's natural cleansing process.

The hydrogen peroxide attacks the contaminant and ''eats'' it - leaving harmless carbon dioxide, water and chloride as its only byproducts.

As the plume moves down gradient toward the subdivision, natural attenuation will remove much of the remaining contamination, all at a fraction of the cost of the initial pump and treat solution.

''By the time in-situ remediation is complete, the Navy will have spent approximately $5 million,'' said Nessmith-Picard. ''Not only have we reduced contamination levels by 95 percent, we've saved more than $9 million and streamlined the clean-up time from 30 years to 5. This process has been a success in every sense of the word.''

Chapelle said the initial contamination level at the source in 1997 was approximately 880 parts per billion, well above the EPA standard of only 2 parts per billion.

''Our goal was to decrease that amount to 100 parts per billion at the source and let nature take care of the rest,'' he said. ''We've hit our goal and exceeded it - the current level at the site is 70 parts per billion. The actual area of the contaminated plume has also decreased by 70 percent and is now close to [Georgia] drinking water standards.''

Contractor CH2M Hill Constructors, Inc., made the fourth and final injection of 11,365 gallons of hydrogen peroxide solution and 12,200 gallons of ferrous iron catalyst in November 2001, followed by an injection of nearly 9,000 gallons of food-grade soybean oil.

The oil feeds naturally occurring bacteria that destroy the remaining contamination and speed natural attenuation.

''The bacteria will take care of what remains long before the plume reaches Crooked River Plantation,'' said Mike Halil, contractor project manager. ''We just helped nature speed up the process.''

USGS officials estimate that any residual contamination will degrade within five years - three years before the plume reaches the neighborhood.

The 25-acre landfill was used from the early to mid-1970's until 1980, well before the advent of strict dumping and disposal regulations.