A REVIEW OF THE REMEDIATION ALTERNATIVES FOR BENZENE

CONTAMINATION AT THE PESTER REFINERY COMPANY SUPERFUND

SITE

Jonathan M. Diller, P.E., CFMfor

University of Florida SWS 6262 – December 2012

Former Refinery Burn Pond

RCRA investigation began in 1986.

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 1996.

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, 416-424.

Environmental Protection Agency. (1992). EPA Superfund Record of Decision Amendment: Pester Refinery Co. (EPA ID: KSD000829846). (Impact factor: NA, government publication)

Environmental Protection Agency. (1998). EPA Superfund Record of Decision Amendment: Pester Refinery Co. (EPA ID: KSD000829846). (Impact factor: NA, government publication)

Environmental Protection Agency. (2005). EPA Superfund Record of Decision Amendment: Pester Refinery Co. (EPA ID: KSD000829846). (Impact factor: NA, government publication)

Environmental Protection Agency. (2011). Site Description: Pester Refinery. (EPA ID: KSD000829846). (Impact factor: NA, government publication)