UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 7

11201 Renner Boulevard Lenexa, Kansas 66219

JUN 2 8 2017 ACTION MEMORANDUM

SUBJECT: Request for a Time-Critical Removal Action for the Ogallala Groundwater OUl site Ogallala, Keith County, Nebraska

FROM:

THRU:

TO:

Susan Fisher, On-Scene Coordinator f <Y /i.1 ,f Response and Removal South Section li>f-- l:J' Adam Ruiz, Chief ~ Respo e and Remov South Section . )

..-r.z~ ~ - S. Buchhol , Chief ent Emergency ResR and Removal Branch

Mary P. Peterson, Director Superfund Division

Site ID: 07HW (RV004)

I. PURPOSE

The purpose of this Action Memorandum is to request funding and document approval for a fund-lead, time-critical removal action for the Ogallala Groundwater Operable Unit (OU)l site (Site), Ogallala, Keith County, Nebraska. The general objective of the proposed removal action described herein for the Site, is for the U.S. Environmental Protection Agency to install vapor mitigation systems in three properties which have been impacted by sub-slab soil gas and/or indoor air contamination from the Site. Installation of vapor mitigation systems are driven by indoor air and/or sub-slab soil gas sample results that demonstrate the presence of contamination levels that exceed the EPA removal action levels (RALs ), for trichloroethylene (TCE). Once the vapor mitigation systems are installed, the EPA Region 7 Superfund Removal Program will collect confirmation indoor air samples to ensure that the systems are working properly. Upon receipt of confirmation samples, showing the vapor mitigation systems are working properly, the systems' operation and maintenance, including any additional confirmation sampling, will be turned over to the Region 7 Superfund Remedial Program. The proposed time-critical removal action is necessary to mitigate the immediate threat to human health and the environment. The health threat has been confirmed by the elevated levels of TCE in groundwater, sub-slab soil gas, and in the indoor air.

TCE is a hazardous substance as defined by the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) §101(14), and is designated a hazardous substance in 40 CFR § 302.4.

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II. SITE CONDITIONS AND BACKGROUND

Site Name: Superfund Site ID#: CERCLIS Number: CERCLIS Sequence #: Site Location: Lat/Long: Potentially Responsible Party: NPL Status: Removal Category: Nationally Significant:

A. Site Description

Ogallala Groundwater OUl 07HW NED986369247 RV004 Ogallala, Keith County, Nebraska 41.128218° north/101.720399° west PRP search ongoing The Site is listed on the NPL Time-Critical No

1. Removal site evaluation

During the potential responsible party (PRP)-lead remedial action at the Ogallala Groundwater OU-I site, the Region 7 Superfund Remedial Program conducted vapor intrusion sampling pursuant to issues and recommendations which had arisen during the previous five-year review that was signed in September 2016. During this sampling effort, elevated levels of chlorinated volatile organic compounds (VOCs), including TCE, associated with the soil and groundwater contamination of Ogallala OU-1, were found in the sub-slab soil gas and inside buildings. This TCE contamination was identified in the sub-slab soil gas and/or indoor air at three buildings at l_evels exceeding the EPA RALs.

The EPA conducted vapor intrusion sampling during November 2016, February 2017, and April 2017 at 20 properties within the area of the groundwater contamination plume. Three of the properties had analytical results above the EPA RALs for TCE. These properties are located within the TCE groundwater plume. Therefore, vapor mitigation systems need to be installed in these three properties. The following table shows the business RALs for TCE, as well as, the sampling results of the three properties above action levels.

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Indoor Soil Air Gas Business Results Results Removal Action levels

Sub-slab Soil

TCE TCE Indoor Air gas Address Sample Date (ug/m3) (ug/m3) (µg/ml) (µg/m3)

November 413 West 1st Street 2016 49.3 402

6 (Business) February 2017 48.6 379 200

April 2017 86.9 375 November

12 North Spruce 2016 5.75 *0.43U 6 (Business) February 2017 10 *1.88 200

April 2017 5.75 *0.859

10 North Spruce November 2016 9.67 **67.2

(Business) February 201 7 17.4 **73

6 200 Indoor Air

April 2017 13.8 **76.3 * Soil gas samples collected outside the building, could not access the crawl space inside ** Samples were collected from crawl space. µg/m3- micrograms per cubic meter

Three previous Action Memorandum's have been executed by the EPA for this site, under Ogallala OU2. On September 28, 2010, an Action Memorandum (RVOOI) was executed by the EPA for Ogallala Groundwater OU2. This Action Memorandum approved a removal action to demolish the former Tip Top Cleaners building, residential garage, commercial parking lot, and residential back yard. After demolition, PCE contaminated soil was excavated and removed from the site. On March 5, 2013, an amended Action Memorandum (RV002) was executed for Ogallala Groundwater OU2. This Action Memorandum approved a 12-month consistency exemption in order to extend the removal action to below 5th Street, adjacent to the source area for the previous removal. An amended Action Memorandum (RV003) was signed on December 3, 2013 for Ogallala Groundwater OU2. The purpose of this amendment was to request a change in the scope of work. This change of work allowed the EPA to investigate and respond to vapor intrusion in the indoor air and sub-slab of properties within the Ogallala Groundwater OU2 site.

2. Physical location

Ogallala, Nebraska is located north of the intersection oflnterstate 80 and U.S. Highway 61, along the South Platte River Valley. The Site includes most of the city of Ogallala. The Site in comprised of two contaminant plumes, which were divided into two OU's, QUI and OU2 by the EPA. The geographical coordinates for the Site are 41.128218° north latitude and 101.720399° west longitude. The nearest surface water feature is the South Platte River, located on the south side of the Site.

3. Site characteristics

OUI consists of groundwater contamination along the business corridor of U.S. Highway 30 (also known as 1st Street in Ogallala). Typically, residential areas begin one block north of

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1st Street. U.S. Highway 30 parallels railroad tracks of the Union Pacific railroad (UPRR), which are about 450 feet south. The UPRR right-of-way (ROW) through town is irregular but in places can be up to 350 feet wide. Within this ROW are several grain elevators, as well as a scrap metal recycling business. South of the UPRR and west of U.S. Highway 26 are commercial/retail businesses and a Nebraska Public Power facility. South of the UPRR and east of U.S. Highway 26 are a Nebraska Department of Roads facility, a city-owned shooting range that was once a landfill or dump, a sand and gravel quarry, and agricultural land. The South Platte River is about 0.25 mile south of the UPRR. South of the river is U.S. Interstate 80.

A number ofVOCs are present in the plume at OUl, but the primary constituent is TCE in both the shallow aquifer (known as the alluvial aquifer) and the underlying Ogallala aquifer. The approximate lateral extent of the OUl contaminant plume is from West J Street at the Keith County Fairgrounds to the gravel quarry lakes near the Ogallala Redi-Mix property. The TCE contamination forms a long narrow plume, 1.6 miles long and generally follows the direction of groundwater flow. Commercial, residential, and agricultural land uses surround the Site. Above the plume, land use is primarily commercial and light industrial. North of the plume, land use is primarily residential (see attached maps).

The OUl Record of Decision (ROD), was issued by the EPA on April 23, 1999. The ROD identified the American ShiZuki Corporation (ASC, former TRW Inc.) facility at 301 West O Street and the Ogallala Electronics and Manufacturing Inc. (OEMI) facility at 601 West 1st Street as two known sources of contamination.

A consent decree (CD) was entered on October 23, 2000 with TRW Inc. (TRW), American ShiZuki Corporation, and Ogallala Electronics and Manufacturing Inc. OEMI became The Arnold Engineering Company (Arnold). TRW owned and operated an electronics manufacturing facility at 301 West O Street. This property was sold to ASC. Requirements included completion of a well inventory, groundwater extraction and treatment, groundwater monitoring, completion of a treatability study for natural attenuation enhancements, reporting, and institutional controls.

In addition to the two known sources of contamination, potential sources that may be contributors to the contamination include:

• 400 block of West 1st Street • East Railroad Street and East E Street • 800 block of East Riverdale • TCE potential spill area on property east of the former landfill • 300 block of West Railroad Street • Property just east of the US Highway 26 • A commercial/light manufacturing area south of the UPRR tracks and west of

U.S. Highway 26. This area is south of Riverdale Road, north of River Road, and on either side of South Spruce Street

• 500 block of West 1st Street • Southeast corner of the intersection of West D Street and West 2nd Street • 400 block of West 2nd Street

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4. Release or threatened release into the environment of a hazardous substance, or pollutant or contaminant.

The primary contaminant of concern (COC) at this Site is TCE. TCE is designated in 40 CFR § 302.4 as a hazardous substance, as defined by section 101(14) of the CERCLA, and has been detected in the sub-slab soil gas and indoor air inside buildings at the Site.

The EPA has documented TCE concentrations in sub-slab soil gas, and in the indoor air above RALs. Concentrations ofTCE as high as 86.9 µg/m3 have been found in indoor air samples collected at the Site. Concentrations ofTCE as high as 402 µg/m3 have been found in the sub-slab soil gas samples collected at the Site.

5. National Priority List (NPL) status

The Site is listed on the NPL. PRP-lead remedial actions began as early as 1992, and are continuing.

6. Maps, pictures and other graphic representations

Figure 1 is the site location map. Figure 2 is a map showing the groundwater contamination plume.

B. Other Actions to Date

1. Previou.s actions

• 1989 - Nebraska Department of Health (NDOH) first detected VOCs in five of the nine municipal wells serving the City of Ogallala

• 1989-1990 - NDOH initiated a soil gas investigation to identify potential sources of the groundwater contamination

• 1992 - The site was proposed for inclusion on the NPL • 1992 - The ASC and OEMI locations were identified as sources of

contamination • 1993 - The NDOH issued an Administrative Order to the City of Ogallala

mandating that the City's public drinking water source comply with the EPA maximum contaminate levels (MCL) set forth in the Safe Drinking Water Act. The City complied by installing a new well field north of town, and the Administrative Order was no longer in effect as of February 23, 1996

• 1994 - The Site was listed on the NPL • 1994 - ASC implemented a voluntary cleanup action • 1996 - The EPA conducted a Remedial Investigation (RI) at the site • 1999 - The EPA issued a ROD for the Site • 2004 - The EPA conducted additional soil and groundwater investigation at the

Site • 2005 - The PRPs completed a treatability study using in-situ chemical oxidation

to determine if this technology would address the "hot spots" that remained in groundwater. They also installed additional groundwater monitoring wells

• 2009-Following the EPA review of the November 2008 Draft Ground Water Report, the EPA requested that the PRPs take additional response actions

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• 2010-The Nebraska Department of Environmental Quality (NDEQ) conducted an abbreviated preliminary assessment (AP A) at the Schmidt Motors facility

• 2011 - The EPA performed a Site Investigation (SI) at the Schmidt Motors facility, and east of the ASC facility

• 2011 -The PRPs performed Ogallala Formation plume delineation and focused screening level source investigations

2. Current actions

During the PRP-lead remedial action at the Ogallala Groundwater OUl site, the Region 7 Superfund Remedial Program conducted vapor intrusion sampling pursuant to issues and recommendations which had arisen during the previous five-year review signed September 22, 2016. The EPA conducted vapor intrusion sampling during November 2016, February 2017, and April 2017 at 20 properties within the area of the groundwater contamination plume. As a result of this sampling, elevated levels of chlorinated VOCs, including TCE, associated with the soil and groundwater contamination of Ogallal~ OUl, were found in the sub-slab soil gas and inside buildings. Three of the properties had analytical results above the EPA RALs for TCE. These properties are located within the TCE groundwater plume. Therefore, vapor mitigation systems need to be installed in these three properties.

C. State and Local Authorities' Roles

1. State and local actions to date

In 1989, the NDOH detected VOCs in five of the nine municipal wells serving the city of Ogallala. Following the initial detections of chlorinated solvents in Ogallala's municipal well field, the state initiated a soil gas investigation to identify potential sources of the groundwater contamination. The soil gas investigation identified a number of potential sources of the chlorinated solvent plume, as well as several sites that were addressed by the state leaking underground storage tank program. The soil gas survey concluded that the sources of groundwater contamination were at or near the following facilities which would become part of OUl: ASC, Helmuth Cleaners, OEMI, and the former TRW /Goodall facility.

On February 2, 1993, NDOH issued an Administrative Order to the city of Ogallala mandating that the city's public drinking water source comply with the MCLs. The city complied by installing a new well field north of town, and the Administrative Order was no longer in effect as of February 23, 1996.

The ASC implemented a voluntary cleanup action through the NDEQ in 1994 with installation and operation of a groundwater extraction and treatment system.

In November 2010, the NDEQ conducted an APA at the Schmidt Motors facility. Based on its observations and findings during the AP A, the NDEQ recommended an SI, including collection of environmental samples, to determine whether Schmidt Motors was a source contributing to the VOC plume associated with the Ogallala Groundwater Contamination site, OUl.

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2. Potential for continued State/local response

The EPA has determined that a fund-lead removal action at the Ogallala Groundwater QUI Site is warranted with the EPA as the lead agency. The NDEQ is supportive of the EPA responding to this threat using the EP A's removal authority.

III. THREATS TO PUBLIC HEALTH OR WELFARE OR THE ENVIRONMENT, AND STATUTORY AND REGULATORY AUTHORITIES

A. Threats to Public Health or Welfare

TCE and its degradation products are hazardous substances as defined in section 101 ( 14) of CERCLA and as designated in 40 CFR § 302.4. TCE has been detected in sub-slab soil gas and/or indoor air samples at the Site at levels that exceed the EPA's RALs. Concentrations ofTCE as high as 86.9 µg/m3 have been found in the indoor air samples collected at the Site. Concentrations ofTCE as high as 402 µg/m3 have been found in the sub-slab soil gas samples collected at the Site.

The EPA has classified TCE as "carcinogenic to humans" by all routes of exposure. This conclusion is based on convincing evidence of a causal association between TCE exposure in humans and kidney cancer. The human evidence of carcinogenicity from epidemiologic studies ofTCE exposure is strong for non-Hodgkin lymphoma (NHL), but less convincing than for kidney cancer, and more limited for liver and biliary tract cancer. The available epidemiologic studies also provide more limited evidence of an association between TCE exposure and other types of cancer, including bladder, esophageal, prostate, cervical, breast, and childhood leukemia. Sufficient evidence supports a mutagenic mode of action for kidney tumors, but not the other cancer types. Adverse non-cancer health effects associated with TCE inhalation exposure include hepatic, renal, neurological, immunological, reproductive, and developmental effects. The most sensitive observed adverse effects are autoimmune disease following chronic exposure in adults and heart defects following exposure during early pregnancy, followed by nephrotoxicity (kidney effects) following chronic exposure in adults.

Where the EPA determines, based on the factors set forth in 40 CFR § 300.415(b )(2), that there is a threat to public health or welfare or the environment, the lead agency may take any appropriate removal action to abate, prevent, minimize, stabilize, mitigate or eliminate the release or threat of release. The factors in 40 CFR § 300.415(b )(2) that apply to this Site are:

40 CFR §300.415(b)(2)(i)- Actual or potential exposure to nearby human populations, animals, or the food chain from hazardous substances, or pollutants, or contaminants.

TCE has been detected at elevated concentrations in sub-slab soil gas and/or indoor air samples at three properties located at the Site.

Vapor intrusion occurs when vapors of sufficient toxicity and volatility emanating from contaminated soil and/or groundwater migrate through the vadose zone into overlying structures. Site associated VOCs, which include TCE, produce vapors that can enter buildings through preferential pathways (cracks, utility corridors, etc.) in the foundation or into a basement with a dirt floor, concrete slab or crawl space.

TCE is a hazardous substance as set forth in CERCLA § 101(14) and as designated at 40 CFR § 302.4. The EPA sub-slab soil gas and indoor air sampling results indicate that the TCE vapors are

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migrating into buildings. Three buildings have been identified as having TCE above RALs in sub-slab soil gas and/or indoor air.

40 CFR § 300.415(b)(2(vii) - The availability of other appropriate federal or state response mechanisms to respond to the release.

The state has requested that the EPA respond to this release. There are no other known appropriate federal or state response mechanisms available to respond to this release.

IV. ENDANGERMENT DETERMINATION

Actual or threatened releases of hazardous substances from the Site may present an imminent and substantial endangerment to public health, or welfare, or the environment. The EPA conducted vapor intrusion sampling during November 2016, February 2017, and April 2017 at 20 properties within the area of the groundwater contamination plume. As a result of this sampling effort, levels ofTCE above RALs, associated with the soil and groundwater contamination of Ogallala OUl, were found in the sub­slab soil gas and/or indoor air in three properties located at the site.

V. PROPOSED ACTIONS AND ESTIMATED COSTS

A. Proposed Actions

1. Proposed action description

The EPA sub-slab soil gas and indoor air sampling results indicate that TCE vapors have migrated into buildings at the Site.

To mitigate threats posed by the presence ofTCE in sub-slab soil gas vapor and indoor air at the Site the following action are proposed: design and install vapor mitigation systems in the three buildings identified as having TCE concentrations above the RALs; develop and implement a vapor mitigation system performance sample plan to confirm that the EPA indoor health standards are achieved for TCE following installation of vapor mitigation systems. Once the vapor mitigation systems are installed, the EPA Region 7 Superfund Removal Program will collect confirmation indoor air samples to ensure that the systems are working properly. Upon receipt of confirmation samples, showing the vapor mitigation systems are working properly, the system operation and maintenance, including any additional confirmation sampling, will be turned over to the EPA Region 7 Superfund Remedial Program. Mitigation activities may include: installation of a sub-slab depressurization system; sealing cracks in walls and floors of the basements; sealing or fixing drains that could provide a pathway for vapor intrusion; and installation of barrier systems, which could include floor sealant, poly sheeting, etc.

2. Contribution to remedial performance

The Site is listed on the NPL. It is expected that the removal action provided for herein will contribute to remedial performance, and will not adversely affect any future remedial performance for the Site.

3. Applicable or Relevant and Appropriate Requirements (ARARs)

Section 300.415(j) of the NCP provides that removal actions shall, to the extent

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practicable considering the exigencies of the situation, attain ARARs under federal environmental or state environmental facility siting laws.

Federal

• 16 U.S.C. § 470 et seq.: National Historic Preservation Act of 1966 • 29 CFR Part 1910: Occupational Safety and Health Standards: General Industry • 40 CFR Part 63: National Emission Standards for Hazardous Air Pollutants

ARARs were formally requested from the state of Nebraska on June 6, 2017 and will be addressed during this action to the extent practicable.

4. Project Schedule

This time-critical response action will begin immediately upon approval of this Action Memorandum. It is anticipated that the project will be completed by winter 2017.

B. Estimated Costs

The costs associated with this removal action are estimated as follows:

Extramural cost"s: Removal Costs Contingency (20 percent) Removal Project Ceiling

$50,000 $10,000 $60,000

EPA direct and indirect costs, although cost recoverable, do not count toward the Removal Ceiling for this removal action. Refer to the enforcement section for breakout of these costs.

VII. EXPECTED CHANGE IN THE SITUATION SHOULD ACTION BE DELAYED OR NOT TAKEN

Delayed action will result in a continued threat to public health or welfare or the environment.

VIII. OUTSTANDING POLICY ISSUES

None.

IX. ENFORCEMENT

See the Confidential Enforcement Addendum for this Site. For NCP consistency purposes, it is not a part of this Action Memorandum. The total EPA costs for this removal action based on full cost accounting practices are estimated to be $95,197.

Direct Extramural Costs Direct Intramural Costs EPA Indirect ( 49 .21 % ) Total Project Costs

$60,000 $ 3,801 $31,396 $95,197

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Direct costs include direct extramural and direct intramural costs. Indirect costs are calculated based on an estimated indirect cost rate expressed as a percentage of site-specific direct costs, consistent with the full cost-accounting methodology effective October 2, 2000. These estimates do not include prejudgment interest, do not take into account other enforcement costs, including Department of Justice costs, and may be adjusted during the course of a removal action. The estimates are for illustrative purposes only and their use is not intended to create any rights for responsible parties. Neither the lack of a total cost estimate nor deviation of actual total costs from this estimate will affect the United States' right to recovery.

X. RECOMMENDATION

This decision document represents the selected removal action for the Ogallala Groundwater OUl Site, in Ogallala Nebraska, developed in accordance with CERCLA, as amended, and is not inconsistent with the NCP. This decision is based on the administrative record for the Site.

Conditions at the Site meet NCP § 300.415(b) criteria for a removal action, and I recommend your approval of this proposed project. The removal project ceiling, if approved will be $60,000. This amount comes from the Regional Removal Allowance.

Approved:

Mary~ erson, Director Superfund Division

Attachments: 1. Site location map 2. Map showing the groundwater contamination plume 3. Enforcement Addendum

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