A REVIEW OF THE REMEDIATION ALTERNATIVES FOR BENZENE CONTAMINATION AT THE PESTER REFINERY COMPANY SUPERFUND SITE Jonathan M. Diller, P.E., CFM for University of Florida SWS 6262 – December 2012

 Former Refinery Burn Pond  RCRA investigation began in  Remedial action began in 1992 with an interceptor trench.  The trench was located between the pond and the nearby river - the West Branch Walnut Creek.

 Contaminants of Concern:  The 1992 ROD listed 11 compounds as COCs for the burn pond soils -10 aromatics and barium.  The 1998 ROD listed 18 compounds as COCs for groundwater - 13 organics and 5 inorganics.

 10 of the COCs for groundwater were not listed as COCs for the soils.  In 1998 the burn pond and the soils beneath were classified as one operational unit (OU1) and the groundwater as another (OU2).  It was decided to take no remedial action on the groundwater (OU2): not even collecting detailed groundwater monitoring data.

 The ROD of 1995 merged OU1 and OU2 into one operational unit.  It set forth the requirement for establishing a groundwater monitoring program.  Data collection began in  This data showed that benzene was a contaminant that consistently exceeded its MCL.

 Benzene is a known carcinogen.  Benzene has been shown to be most harmful when inhaled or ingested.  Benzene has a low maximum contaminant level (MCL) of 5 parts per billion.

 This data indicates that there is a need to address the benzene contamination in the groundwater.  The pond soils have been excavated and solidified and a cap placed over the old pond.  It may not be necessary to address the contaminated pond and soils as a source but this will need to be monitored.

 The source of the benzene is not understood. It was never identified as a contaminant in the soil.  This leaves treatment of the groundwater as the only option to address the contamination.  So what are the groundwater treatment options?

 One option is pump and treat.  This option would require a substantial capital and ongoing operations and maintenance cost.  The necessary duration of remediation activities is uncertain.

 A minimum anticipated capital cost for a pump and treat system would be $225,000.  Again this would require ongoing operations and maintenance cost with an uncertain system life because the source is not known.

 Another option is passive bioremediation using poplar trees.  This option was identified by Barac, et al. in a paper regarding the containment of a BTEX plume using poplar trees.  This study showed the effectiveness of using a row of poplar trees to confine and reduce the extent of a BTEX plume.

 This approach has a much lower capital cost and practically no ongoing maintenance costs.  The estimated installation cost for a containment row of poplar trees is approximately $40,000 including design cost.  There would be no ongoing maintenance costs after the first two years.

 The row of poplar trees would be between the pond and the West Branch Walnut Creek.  Since the site itself is restricted use the groundwater contamination under the site is not a concern.  This option is a low cost potential remediation system to address the migration of benzene contaminated groundwater from the site.

SUMMARY and CONCLUSIONS  The Pester site has a long history of minimal remediation activities either required or performed.  No efforts have been made to address the source of benzene contamination in the groundwater or remediate the contamination.

 The installation of high capital cost solutions with ongoing maintenance costs is unlikely to be required.  The installation of the poplars is a relatively low capital cost alternative with practically no ongoing maintenance costs.  The solution has no decom- missioning cost if it is ineffective. You simply have a nice row of screening trees along the creek.

References Barac, T., Weyens, N., Oeyen, L., Taghavi, S., Lelie, D., Dubin, D.,... Vangronsveld, J. (2009). Field Note: Hydraulic Containment Of A Btex Plume Using Poplar Trees. International Journal of Phytoremediation, Environmental Protection Agency. (1992). EPA Superfund Record of Decision Amendment: Pester Refinery Co. (EPA ID: KSD ). (Impact factor: NA, government publication) Environmental Protection Agency. (1998). EPA Superfund Record of Decision Amendment: Pester Refinery Co. (EPA ID: KSD ). (Impact factor: NA, government publication) Environmental Protection Agency. (2005). EPA Superfund Record of Decision Amendment: Pester Refinery Co. (EPA ID: KSD ). (Impact factor: NA, government publication) Environmental Protection Agency. (2011). Site Description: Pester Refinery. (EPA ID: KSD ). (Impact factor: NA, government publication)