united states environmental protection … · north run creek flows into talley's pond, ......

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION III

1650 Arch Street Philadelphia, Pennsylvania 19103-2029 SDMS DocID

SUBJECT: Rentokil, Inc. Superfund Site EPA Determination of Necessary Additional Response Action

FROM: Andrew Palestini, Remedial Project Manager DE/VA/WV Remedial Branch

TO: Site File - EPA Region III CERCLA Records Center

In accordance with Section VILA of the Consent Decree entered into between Virginia Properties, Inc. (VPI) and EPA on September 30, 1994, EPA has determined that additional response actions are necessary to carry out the remedial action selected in the Record of Decision (ROD) for the Rentokil, Inc. Superfund Site, which is located in Henrico County, Virginia. EPA's determination is based on monitoring data demonstrating contamination of the subsoils outside of the constructed containment system that is causing the ground water to exceed Maximum Contaminant Levels (MCLs). -

EPA's determination is supported by a supplement to the Administrative Record for the remedial action at the Site. The documents forming the basis for EPA's determination have been incorporated into the Administrative Record in accordance with Section 300.835(a)(2) of the NCP, 40 C.F.R. § 300.835(a)(2). The Administrative Record is available for review during business hours at the information repository in the offices of EPA Region I'll at 1650 Arch Street, Philadelphia, PA, and at an information repository at the Henrico County Municipal Reference and Law Library, 4301 E. Parham Road, Henrico, VA 23228, Monday - Friday, 8AM - 4:30PM, (804) 501-4780. The Administrative Record may also be found on the internet at: http://loggeThead.epa.gov/arweb/public/search results.jsp?siteid=VAD071040752

I. SUMMARY OF THE SITE HISTORY, CONDITIONS AND REMEDIATION

A. Site History

The Site, a former wood-preserving facility, is located at the intersection of Peyton Street and Ackley Avenue in Henrico County, Virginia. Wood-treatment operations were performed at the Site from 1957 to 1990 with different chemicals used over the years. These chemicals included pentachlofophenol (PCP), chromium zinc arsenate (CZA), copper chromated arsenate (CCA), fire retardant, creosote, and xylene.

Operations at the facility over the years included wood treatment, storage of wood, and disposal of wastes, all which led to the contamination of the Site. Throughout the operational history of the Site, freshly treated wood was allowed to drip onto the soil-and then stored in various open areas of the Site. In addition, wastes from early operations were reportedly

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discharged to a blow-down sump. The previous owners of the Site cleaned and replaced the blow-down sump in 1963 with a concrete holding pond and constructed a covered unlined lagoon. The concrete holding pond was linked to the covered unlined lagoon by an underground drainpipe. The drainpipe was closed and apparently abandoned in place in 1974, with no details given of any testing, sampling, or the method of abandonment. The soil, sediments, and ground water at the Site are contaminated as a result of these past operations. The contamination in the subsoils includes dense non-aqueous phase liquids (DNAPLs).

B. Site Conditions

During the 1980s, EPA assessed the Site and determined that the Site qualified for detailed evaluation and, if necessary, cleanup by EPA's Superfund program. In March 1989, in accordance with Section 105 of CERCLA and Section 300.425 of the NCP, the Site was formally added to the National Priorities List, which is the list of national priorities among the known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the United States and its territories. See 42 U.S.C. § 9605; 40 C.F.R. § 300.425.

The Site includes the former wood-treating process area, the wood-drying areas,'Wetland Area A, and former Wetland Areas B and C. None of the wetland areas were used in the wood-treating process; these areas became contaminated by runoff from the process and wood-drying areas. Wetland Area A, the area immediately north of the former process area, is located within the flood plain of an unnamed tributary of North Run, referred to as North Run Creek. Surface water runoff from the northern portion of the Site flowed towards Wetland Area A and into North Run Creek. North Run Creek flows into Talley's Pond, then to North Run, Upham Creek, and finally into the Chickahominy River.

There are two well-defined aquifers separated by a clay hardpan in the area of the Site. The upper, or perched, aquifer extends from the ground surface to approximately four to seven feet below grade. The lower, or saprolitic, aquifer extends from the bottom of the hardpan (approximately 7-10 feet below grade) to approximately^ feet below grade. Below the saprolitic aquifer is the bedrock aquifer.

Prior to construction of the containment system (cap and slurry wall), ground water in both the perched and saprolitic aquifers tended to flow in a northeasterly direction at a relatively low rate (approximately 1 foot per year). The cap and slurry wall contains the residual product in site soils as well as constituent-affected ground water. The containment structure diverts normal ground water flow around the structure.

The slurry wall inhibits normal ground water flow from entering the containment area on the southwestern side and prevents ground water from leaving the containment area on the northeastern, or down gradient, side. The slurry wall also creates a flat gradient on the north side, as is evidenced by water level data since monitoring was initiated.

C. Site Remedy

1. Selection of Remedial Action

The Record of Decision (ROD) for the Site was signed on June 22, 1993. Although Remedial Action Objectives (RAOs) were not specifically listed in the ROD, they are suggested in the ROD's list of the major components of the remedy: -

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Source Control Response Objectives

• Reduce risks to human health by preventing direct contact with, and ingestion of, contaminants in the Site soil, wetland sediments, and pond sediments, and by preventing potential ingestion of contaminated ground water;

• Reduce risks to the environment by preventing direct contact with, and ingestion of, contaminants in the wetland sediments; and

• Minimize the migration of contaminants from Site soil and wetland sediments that could result in surface water concentrations in excess of Ambient Water Quality Criteria.

Management of Ground Water Migration Response Objectives

• Eliminate or minimize the threat posed to human health and the environment by preventing exposure to the contaminants in the ground water; and

• Contain contaminated ground water to protect human health and the environment.

2. ROD Amendment

The ROD for the Site included on-site low temperature thermal desorption treatment of the "hot spot" soils." On August 27, 1996, EPA issued a ROD Amendment to delete this requirement for treatment of the "hot spots" at the Site because of the findings of ground water modeling performed as part of the Value Engineering analysis completed during the design phase. The findings from the ground water modeling demonstrated that, following construction of the cap and slurry wall and operation of the dewatering system, contaminants in the soil will be effectively immobilized and will not move away from the Site in the ground water; thus, treatment of the "hot spots" is not warranted.

The RAOs utilized in the ROD Amendment are the same as those used in the ROD. EPA's selected remedy described in the ROD Amendment addresses risks to human health and the environment from soil, ground water, and sediment contamination. The main components of the selected remedy in the ROD Amendment include:

• Demolish existing structures.

• Remove unlined pond.

• Dispose of any drums excavated from the Fill Area.

• Surface soils exceeding cleanup levels which lie outside the area to be capped will be consolidated to the area of the Site to be capped.

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• Dewater soils excavated from Wetlands A, B, and C. Excavated wetlands will be revegetated with appropriate plant species as approved by EPA.

• Construct containment system consisting of multilayer cap, slurry wall, and dewatering system.

• Excavate and dispose of sediment in the oxbow of North Run Creek to the area onsite to be capped.

• Implement institutional Controls to prohibit residential development of the Site and/or use of the ground water.

• Perform ground water monitoring for at least 30 years to determine whether the ground water beyond the slurry wall exceeds MCLs.

At the time of the ROD Amendment, the containment system was to be constructed as a multilayer RCRA subtitle C cap planned to cover approximately the ten acres of the Site where contamination in the surface soil exceeded the Site-specific cleanup levels (see Figure 1). The cap was to be extended into the contaminated portion of the wetlands to the extent possible with any wetlands lost due to capping being replaced. A slurry wall would be constructed around the perimeter of the cap to ensure the contamination is adequately contained. In addition, a dewatering system would be constructed inside of the containment system to keep ground water within the slurry wall from building up and creating pressure on the slurry wall, to treat any ' DNAPL collected, and to cause an inward hydraulic gradient in the subsurface such that ground water would not flow outward from the containment system. -

3. Implementation of the Remedial Action

On September 30, 1994, VPI and EPA entered into a Consent Decree, which provided that VPI would implement the remedial action at the Site.

During the pre-final design effort (November 1996 to April 1997), VPI requested EPA's approval to revise the alignment of the north slurry wall and, as a result, reduce the extent of the cap (see Figure 2). This request was made to potentially accommodate a rail spur in the future to service possible commercial/light industrial development of the Site. Since arsenic was the principal contaminant in the surface soil in that area, EPA directed VPI to sample the northern portion of the Site property to determine whether arsenic concentrations in surface soil exceeded the site-specific cleanup levels. The analytical results indicated that surface soils on the northern portion of the property had levels of arsenic below the site-specific cleanup level. As a result, EPA and VDEQ agreed with VPI's proposed modification to the alignment of the northern slurry wall.

The selected remedy also included ground water monitoring (Figure 3). The analytical results of the ground water at monitoring well VPMW-2 have consistently shown detections of PCP exceeding the ground water clean-up level of 1 ug/L by several orders of magnitude (Figure 4). In addition, several other contaminants have been detected above health-based levels at this well over the years, although the contaminants and the levels vary. Detecting contamination at

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VPMW-2 was unexpected since there were no monitoring wells placed in the vicinity of VPMW-2 during the remedial investigation. Initially, EPA continued regular monitoring to determine whether this contamination was an anomaly due to soil disturbance in that area from construction of the slurry wall. As the levels of PCP remained relatively constant at this location, EPA directed VPI to conduct additional investigations.

Initially, EPA directed VPI to better define the extent of the PCP contamination in the area of VPMW-2 . This was accomplished by installing the following delineation wells in 2004: VPDW-1, VPDW-2, and VPDW-3. These wells are located cross-gradient and down-gradient of

1 VPMW-2, and all within 100 feet of this monitoring well. As these delineation wells showed varying levels of PCP, EPA directed VPI to conduct a test to determine the ability to remove the PCP.

From November 2007 to April 2008, VPI performed a ground water extraction study on wells VPMW-02, VPDW-01, and VPDW-03, the three wells that persistently exhibited high concentrations of PCP. The work consisted of pumping 30,000 gallons of ground water from these three wells. It was originally projected that the study would take nine weeks to implement. As part of the study, ground water samples would be taken before the start of extraction, weekly during the projected four weeks of extraction, and weekly for an additional four weeks after the completion of the extraction. However, because of the extremely slow recovery rate of these wells (an average of less than 0.10 gallons per minute in each well), the test was extended to 21 weeks. During the extraction, a few smears of PCP were seen on the extraction tubing. After carefully analyzing the data, EPA determined that the contamination detected in the area north of the existing containment system (in the vicinity of monitoring well VPMW-2) is not emanating from the interior of the containment system; rather, it is part of the contamination from past operations that was always at that location. In addition, the data also indicated that pumping from the saprolite geological formation and collection trenches would not be viable treatment remedies because of the extremely slow recovery rate and that in-situ treatment would not be feasible because of the inability to sufficiently deliver chemicals or nutrients to the contamination because of the tight geological formation.

Because the concentrations of PCP in these wells remained several orders of magnitude above the clean-up level for PCP, EPA notified VPI on March 3, 2011, in accordance with the terms of the Consent Decree, that a comprehensive remediation strategy was required to address the problem, and that this strategy must be developed within the framework of a focused feasibility study (FFS). VPI agreed to perform the FFS on March 21, 2011, and submitted a work plan on May 10, 2011. EPA approved the work plan on October 13, 2011.

, The purpose of the FFS was to present and evaluate remedial alternatives to control exposure and migration of the PCP contamination in the area north of the containment system known as the FFS Area (Figure 5). However, this evaluation required additional field work. hv October 2011, VPI installed two additional delineation wells, VPDW-04 and VPDW-05, which are located approximately 120 feet down gradient of VPMW-2 and took soil samples from 25 locations in the FFS Area in addition to the regular semi-annual sampling of the ground water monitoring wells. Additionally, VPDW-4 was sampled again in February 2012 to confirm the unexpected high levels of PCP detected there. This data was used in conjunction with the 11 years of ground water monitoring well data to evaluate impacts to ground water from PCP concentrations in soil as well as to define the nature and extent of PCP ground water and saprolite soil contamination located in the FFS Area.

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The analytical data of the soil samples indicate that concentrations of PCP in surface soil in the FFS Area are well below the ROD clean-up level of 48 mg/kg for direct contact but that there are areas of subsurface soil with elevated levels of PCP. As such, the alternatives in the FFS did not need to consider a direct contact exposure evaluation for PCP in soils.

Further, areas of subsurface soil contamination were detected during the FFS. As with the ground water contamination, the subsurface soil contamination is sporadic both laterally and at ^ depth. The soil borings with the highest concentrations of PCP in the subsurface soil are VPSB-09, VPSB-12, VPSB-19, VPSB-22, and VPSB-23. The highest concentrations of PCP at these locations vary from 430 mg/kg at VPSB-09 to 21,000 mg/kg at VPSB-22. For the most part, the analytical results of PCP sampling in the remaining soil borings were either low levels or non-detect, further evidence of the sporadic nature of the contamination in this area.

The data from the ground water extraction study showed that pumping the ground water had no effect on the levels of PCP and that in-situ biological or chemical treatment were not feasible because the tight formation of the aquifer did not allow for the delivery of nutrients or chemicals required of these technologies.

The subsurface soil contamination and the evidence of smears, as indicated previously, have led EPA to conclude that waste is present in the FFS Area. But, treatment of the waste is not feasible for the reasons listed regarding the tight geologic nature of the formation. As such, the remedial action objectives developed for the FFS are:

1. Prevent human ingestion of ground water containing concentrations of PCP above the MCLof 1 ug/L.

2. Prevent migration of PCP in the shallow aquifer to assure no additional degradation of the shallow aquifer.

3. Where practicable, treat source material in the soil to protect ground water. •

As such, three alternatives were evaluated in the FFS: No Action; Extension of the Existing Containment System; and Phytoremediation. All of the alternatives would prevent human ingestion of ground water concentrations of PCP above the clean-up level of 1 ug/L because of the existing institutional controls that were put in place by VPI as a requirement of the ROD Amendment. EPA has determined that Extension of the Existing Containment System is the most viable alternative to address the PCP contamination north of the existing containment . system. The "No Action" alternative would not prevent migration of PCP at the Site. EPA has not chosen Phytoremediation because this technology has not been proven at a site contaminated with PCP.

The extended containment system will be constructed within the footprint of the containment system selected in the ROD and ROD Amendment. Thus, the extension of the containment system is consistent with the remedial action selected for the Site by EPA, and no -ROD Amendment or Explanation of Significant Difference is required. The exact location of the extension of the containment system will be determined during the remedial design but, to the extent practicable, should include the area up to and including VPSB-9 in the north, up to and including VPPZ-10 to the east, and tied into the existing slurry wall to the west. The existing slurry wall shall form the southern boundary. Additional monitoring well(s) shall be constructed beyond the northern boundary of the extended containment system in the down gradient

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direction between the slurry wall and VPMW-4 to verify that contamination is not leaking through the slurry wall. The number and location of the monitoring well(s) will be determined during the remedial design. • v

In accordance with the Consent Decree, EPA will provide VPI with written notification that the additional response action described above is necessary to carry out the remedial action selected in the ROD. Within 45 days of EPA's notice (or such longer time as EPA specifies), VPI will be required to submit a work plan for the extension of the containment system. EPA's determination that the selected additional response action is necessary will be subject to the dispute resolution provisions of the Consent Decree.

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NewFields Midtown Two Plaza

1349 West Peachtree Street, Suite 2000 Atlanta, Georgia 30309

Tel: 404-347-9050 - Fax: 404-347-9080 www. newfields .com

Figure 2 Slurry Wall and Cap

EXPLANATION OF SIGNIFICANT DIFFERENCES for the

Rentokil, Inc. Superfund Site

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Legend I | Site Outline

• Monitoring Wells

® Delineation Wells

Slurry Wall

0 60 120 240 360 • Feet



Tel: 404-347-9050 - Fax: 404-347-9080 www.newfields.com

Figure 3 Groundwater Monitoring Wells



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LEGEND Groundwate r R e s u l t s Oc tober 24 - 2 8 , 2011

and February 17, 2012

• No PCP was detected.

The detected PCP concentrations do not exceed the MCL (1 ug/L).

— The detected PCP concentrations exceed the MCL.

Slurry Wail

Divider Walls

Tank

Lateral Location

Groundwater Flow Direction Measured October 24 - 28, 2011

MCL = Maximum Contaminant Level for Drinking Water

PCP = Pentachlorophenol ug/L = micrograms per liter, or parts

per billion D = Diluted Sample Analysis J = Estimated Concentration P = The relative percent difference between

the primary and confirmatory column/ detector is >40%. The lower value was reported.

H = Analyzed outside holding time. * = LCS/LCSD outside control limits.

USDA, NAIP, and USGS DOQQ Aerial Photograph.

...Projects/VAProp/Av9GIS/Richmond.mxd




Virginia Properties, Inc., a Rentokil Initial company Richmond, Virginia Site

Updated Focused Feasibility Study Soil Evaluation/Semi-Annual Groundwater

Monitoring Report ~ November 2012

Figure 4 MCL Exceedances for

Pentachlorophenol in Groundwater (Oct. 2011 & Feb. 2012)

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CAPPED AREA

Slurry Wall

•'*UKs lint, tontati '.=V, ^ j . . tL>r':>1'Kj 'WiLtfM u*l >*. Mt; amiMlB.ld^gj«lfffiMi<iy

N

qfa E S

Legend

Site Outline

FFS Area

Slurry Wall

0 50 100 200 300 ^ F e e t




Figure 5 FFS Area



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united states environmental protection … · north run creek flows into talley's pond, ......

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