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Stono Phosphate Works

National Information


Wetland excavation (source: EPAOSC.net)

Additional Resources
Site Summary Profile
EPA ID: SC0002316404
Location: Charleston, Charleston County, SC
Lat/Long: 32.831108, -079.963852
Congressional District: 01
NPL Status: non-NPL
Affected Media: Ground water, Sediment, Soil
Cleanup Status: Removal Action Completed – ground water monitoring underway
Human Exposure Under Control: NA
Groundwater Migration Under Control: NA
Sitewide Ready for Anticipated Use: NA
Site Reuse/Redevelopment: In continued use – a marina and a marina-related storage facility are located on site
Site Manager: Ken Mallary (mallary.ken@epa.gov)

Current Site Status

The Stono Phosphate Works site includes an area where a phosphate fertilizer facility operated from 1900 until the late 1950s. Dolphin Cove Marina and marina-related storage facilities currently operate at the site.  Formerly operated by Virginia Carolina Chemical Company, the site is one of several former phosphate fertilizer facilities located throughout the southeastern United States that EPA, Exxon Mobil Corporation (ExxonMobil) and state agencies are addressing through an innovative cleanup agreement. The agreement allows ExxonMobil to use a standard cleanup approach across these sites, using EPA-authorized Superfund removal actions.

Because of contamination associated with the former phosphate fertilizer facility, EPA authorized a removal action, a short-term cleanup, at the site. EPA, the South Carolina Department of Health and Environmental Control (SCDHEC), and ExxonMobil, the site’s potentially responsible party (PRP), have investigated site conditions and taken steps to clean up the site in order to protect people and the environment from contamination. Site contamination does not currently threaten people living and working near the site. A water line connects businesses on site as well as residents and businesses near the site to the public water supply. By cleaning up the site and monitoring ground water, EPA, SCDHEC and ExxonMobil continue to protect people and the environment from site contamination.

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Site Location and Background

The 15-acre site is located on Austin Avenue between Interstate 26 and the Ashley River in Charleston, South Carolina. The chemical manufacturing facility borders the site to the north, the Atlantic Phosphate Works site borders the site to the south, Interstate 26 borders the site to the east and the Ashley River borders the site to the west. The Rosemont neighborhood, which includes low-income and minority residents, is located north of the site. The site’s broader surroundings include industrial and residential land uses.

From the late 1800s to the early 1900s, Virginia Carolina Chemical Company (VCC) produced phosphate fertilizer at several sites throughout the southeastern United States, including the Stono Phosphate site. Fertilizer manufacturing operations took place at the site from 1900 until the late 1950s. Operations involved combining phosphate ores with sulfuric acid to produce phosphoric acid, the building block of nitrogen-phosphorus-potassium agricultural fertilizers. Operators produced sulfuric acid at the site and stored it in lead-insulated chambers.

In the 1970s, Dolphin Cove Marina and marina-related storage facilities began operating at the site. Prior to cleanup activities, dry dock storage operations occurred at the site and marina-related wastes were disposed of at the site. Currently, Dolphin Cove Marina uses structures at the site for marina operations, including a dry dock storage area. A restaurant is also located on one corner of the site property.

While ExxonMobil never owned or operated facilities at the site, the company accepted responsibility for site cleanup by way of a corporate merger in 1999. Today, ExxonMobil is actively cleaning up a number of the VCC sites across the southeast, including the Stono Phosphate site.

View site location map.

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Threats and Contaminants

Site investigations found contamination in ground water, sediment and soil that could potentially harm people in the area. Contamination resulted from fertilizer manufacturing operations at the site. Contaminants of concern include lead and arsenic. Low pH conditions are also of concern.

ExxonMobil removed contamination from soil and sediment and cleaned up the site to support industrial uses. EPA determined that there are no threats or unacceptable risks to people working at or visiting the marina area or businesses and residences near the site.

ExxonMobil continues to monitor ground water. Ground water contamination does not affect people near the site because a water line connects residences and businesses to the public water supply.

A fence surrounds the site.

ExxonMobil will place institutional controls on the site property to prohibit use of ground water and residential development.

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Investigation and Cleanup Responsibility / Oversight

ExxonMobil conducted a removal action, a short-term cleanup, and is monitoring the long-term treatment of ground water. EPA and SCDHEC provide oversight of ExxonMobil’s activities at the site.

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Site Cleanup Plan

In 2004, EPA signed an Action Memorandum, which authorized the use of a non-time-critical removal action to address the contamination at the site and described EPA’s preferred plan for addressing it. Based upon additional information, EPA issued a second Action Memorandum to update the cleanup plan in 2010. The revised plan included the following activities:

EPA OSC.net provides more information about the removal activities.

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Cleanup Progress

In 2011, ExxonMobil conducted cleanup activities at the site. ExxonMobil dug up and treated 30,000 to 40,000 cubic yards of contaminated soil and sediment and disposed of the material off site. ExxonMobil restored affected wetlands following the completion of the sediment cleanup activities. ExxonMobil mixed a chemical additive with the backfill soil and placed the soil below the water table to help reduce levels of lead and arsenic in ground water. On June 16, 2011, EPA and representatives from SCDHEC, ExxonMobil and their consultants conducted the final inspection for the removal action.

ExxonMobil will continue ground water monitoring to determine the effectiveness of the removal action. Parties expect lead and arsenic levels in ground water to decline within five to 10 years.

PRPs completed the NTCRA in 2011.


EPA OSC.net provides more information about the removal activities.

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Enforcement Activities

In October 2000, EPA and ExxonMobil entered into a legal agreement, in which Exxon Mobil agreed to conduct an engineering evaluation/cost analysis to fully investigate site-related contamination and determine potential risks to public health and the environment caused by the release or threatened release of contamination from the site.

In 2004, EPA and ExxonMobil negotiated a legal agreement to conduct the non-time-critical removal action at the site.

ExxonMobil funded site cleanup activities and continues to fund site monitoring and oversight.

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Community Involvement

EPA has worked with the community and its state partner to develop a long-term cleanup plan for the site, reflecting the Agency’s commitment to safe, healthy communities and environmental protection. EPA cannot fulfill its mission without community engagement and public outreach as core components of the program’s activities.

EPA has conducted a range of community involvement activities at the site to solicit community input and to make sure the public remains informed about site activities throughout the cleanup process. Outreach activities have included public notices, fact sheets, interviews and public meetings.  

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Future Work

ExxonMobil will continue to monitor ground water.

ExxonMobil will place institutional controls on the site property to prohibit use of ground water and residential development.

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Additional Information

EPA keeps additional site documents and information in a site information repository at the location below. EPA also posts site documents, when available, on EPA’s CERCLIS Site Profile page. For documents not available on the website, please contact the Region 4 Freedom of Information Office.

Site Repository

Charleston County Public Library
68 Calhoun Street
Charleston, SC 29401

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