### HRS DOCUMENTATION RECORD COVER SHEET

Name of Site: PCE Southeast Contamination

EPA ID No.: NEN000706200

Contact Persons

EPA Contact : Michelle Quick , EPA Region 7 NPL Coordinator Brian Mitchell, EPA Nebraska State Coordinator U.S. Environmental Protection Agency, Region 7

Site Investigation: U.S. Environmental Protection Agency Nebraska Department of Natural Resources

Documentation Record: Kumud Pyaku ryal, Tetra Tech , Inc.

Pathways, Components, or Threats Not Scored

N o releases or impacts to surface water or air have been documented. T he surface water and air migration pathways and t he soil exposure pathway were not scored because these pathways would not affectthe NPL decision.1 

### HRS DOCUMENTATION RECORD

Name of Site: PCE Southeast Contamination EPA Region: 7 Date Prepared: Dec ember 2013 Street Address of Site*: I ntersection of 5 th Street and Lincoln Avenue. City, County, State , Zip : York, York County, Nebraska, 68467 General Location in the State: The site is located in York, near the cente r of York County in southeast Nebraska ( York South (USGS 1969b) (F igure 1; Ref. 3, pp. 1 ).
Topographic Map: The location of the site is shown on the York South Quadrangle, U.S. Geological Survey, 7.5-Minute Series Topographic Map (Ref. 3, p. 1).

Latitude *: 40o 51’ 34.54 ” North (Ref. 3, p. 1)
Longitude*: 97 o 34 ’ 50.21 ” West (Ref. 3, p. 1)
The latitude and longitude listed above specify the approximate location of the center of the ground water plume, located on the north side of the West Nobes Road (Road 12) between Blackburn Avenue and South Delaware Street. It is an area -wide ground water plume with no identified source

.

Scores Ground Water Migration Pathway 86.67 Surface Water Migration Pathway 0 Soil Exposure Pathway 0 Air Migration Pathway 0 HRS SITE SCORE 43.33

Note:

*The street address , coordinates, and contaminant locations presented in this HRS documentation record identify the general area the site is locat ed. They represent one or more locations EPA consider s to be part of the site based on the screening information EPA used to eval uate the site for NPL listing. EPA lists national priorities among the known “releases or threatened releases” of hazardous substances; thus, the focus is on the release, not precisely delineated boundaries. A site is defined as where a hazardous substance has been “deposited, stored, disposed or placed, or has otherwise come to be located.” Generally, HRS scoring and the subsequent listing of a release merely represent the initial determination that a certain area may need to be addressed under the Compre hensive Environmental Response, Compensation, and Liability Act ( CERCLA ). Accordingly, EPA contemplates that the preliminary description of facility boundaries at the time of scoring will be refined as more information is developed
as to where the contami nation has come to be located

.2 WORKSHEET FOR COMPUTING HRS SITE SCORE

S S 2
1. Ground Water Migration Pathway Score (S gw ) (from Table 3-1, line 13) 86.67 7,511.68

2a. Surface Water Overland/Flood Migration Component (from Table 4-1, line 30) 0.00

2b. Ground Water to Surface Water Migration Component (from Table 4- 25, line 28) 0.00

2c. Surface Water Migration Pathway Score (S sw ) Enter the larger of lines 2a and 2b as the pathway score. 0.00 0.00

3. Soil Exposure Pathway Score (S s ) (from Table 5-1, line 22) 0.00 0.00

4. Air Migration Pathway Score (S a ) (from Table 6-1, line 12) 0.00 0.00

5. Total of S gw 2 + S sw 2 + S s 2 + S a 2 7,511.68
6. HRS Site Score Divide the value on line 5 by 4 and take the square root 43.333 TABLE 3 -1.

− GROUND WATER MIGRATION PATHWAY SCORESHEET

Factor Categories and Factors Maximum Value Value Assigned Likelihood of Release to an Aquifer: 1. Observed Release: 550 550 2. Potential to Release: 2a. Containment 10 Not Scored 2b. Net Precipitation 10 Not Scored 2c. Depth to Aquifer 5 Not Scored 2d. Travel Time 35 Not Scored 2e. Potential to Release [lines 2a x (2b + 2c + 2d)] 500 Not Scored 3. Likelihood of Release (higher of lines 1 and 2e) 550 550 Waste Characteristics: 4. Toxicity/Mobility a 1,000 5. Hazardous Waste Quantity a 100 6. Waste Characteristics 100 18 Targets: 7. Nearest Well 50 50 8. Population: 8a. Level I Concentrations b 225.00 8b. Level II Concentrations b 427.25 8c. Potential Contamination b Not Scored 8d. Population (lines 8a + 8b + 8c) b 652.25 9. Resources 5 Not Scored 10. Wellhead Protection Area 20 20 11. Targets (lines 7 + 8d + 9 + 10) b 722.25 GROUND WATER MIGRATION SOURCE FOR AN AQUIFER 12. Aquifer Source [(lines 3 x 6 x 11)/82,500] c 100 86.67 GROUND WATER MIGRATION PATHWAY SCORE 13. Pathway Score (S gw ), (highest value from line 12 for all aquifers evaluated) c 100 86.67

Notes:

a Maximum value applies to waste characteristics category b Maximum value not applicable

c Do not round to nearest integer4 FIGURE 1. –G ROUND W ATER SAMPLING RESULTS MAP5 FIGURE 2. –4- MILE RADIUS MAP6 REFERENCES

Reference Number Description of the Reference

1 U.S. Environmental Protection Agency (EPA). Hazard Ranking System, Final Rule. 55 FR 51533. December 14, 1990. 1 page. On

- line address: http://www.epa.gov/superfund/sites/npl/hrsres/

. A complete copy of the HRS can be obtained at the Regional docket upon request. 2 EPA. Superfund Chemical Data Matrix. January 2004 (March 2012 update). Excerpt. 5 pages. [Note: A complete copy of SCDM is available at http://www.epa.gov/superfund/sites/npl/hrsres/tools/scdm.htm ]. 3 U.S. Department of Interior Geological Survey (USGS). 1969. York South, Nebraska Quadrangle, Missouri, 7.5-Minute Series (topographic) (1969). 1 page. 4 Tetra Tech, Inc. (Tetra Tech). 2012. Removal Site Evaluation/Site Inspection Report for Southeast York Groundwater Site, York, York County, Nebraska. February 16. 397 pages. 5 Tetra Tech, Inc. (Tetra Tech). 2012. Integrated Site Assessment Report for York Tetrachloroethene (PCE) Site, York, York County, Nebraska. February 14. 199 pages

. 6 Seagull Environmental Technologies, Inc. (SETI)

. 2011 . Removal Site Evaluation/Site Inspection Report for Southeast York Groundwater Site, York, York County, Nebraska. February 16. 397 pages. 7 U.S. Geologic Survey (USGS). 2007. Hydrogeologic Setting and Ground

- Water Flow Simulations of the Eastern High Plains Regional Study Area, Nebraska . 32 pages. 8 NDHHS. 2013. Ground water sample result for PWS Well # 77

- 3, from September 6, 2005; September 8, 2009; and September 29, 2011 . On

- line address: http://sdwis

dhhs.ne.gov . Accessed on May 10, 2013. 9 pages. 9 U.S. Geologic Survey ( USGS ) . 2008. Hydrogeology, Chemical Characteristics, and Transport Processes in the Zone of Contribution of a Public-Supply Well in York, Nebraska. Scientific Investigations Report 2008 -5050. 165 pages. 10 U.S. Census Bureau. 2 010. Quickfacts Website. Accessed on March 27, 2013. On

- line address: http://quickfacts.census.gov/qfd/ . 2 pages. 11 Tetra Tech. 2013. Figure 1: Ground Water Sampling Results Map. Revised o n August 5

. 1 page

. 12 Tetra Tech. 2013. Figure 2: 4

- Mile Target Distance Limit (TDL). Revised o n August 5

. 1 page

. 13 EPA. 1992 . EPA Method 8260B, Revision 4 .0. August. 43 pages. 14 Tetra Tech EM, Inc. (Tetra Tech). 2011. The Quality Assurance Project Plan for Removal Site Evaluation/Site Inspection at the Southeast York Groundwater site, York, York County, Nebraska. Contract No. EP- S7 -06-01, Task Order No. 0222

. May 20 . 31 pages. 15 USGS. 2008. Simulations of Ground

- Water Flow, Transport, Age, and Particle Tracking near York, Nebraska, for a study of Transport of Anthropogenic and Natural Contaminants (TANC) to Public Water Wells. 58 pages. 16 EPA. 2013. Envirofacts Database. On

- line Address: https://oaspub.epa.gov/enviro/

. Accessed on August 2. 4 pages. 17 NDHSS . 2013. Drinking Water Branch

– Drinking Water Watch Database. On

- line Address: http://sdwis -dhhs.ne.gov:8000/DWW/ . Accessed on August 5. 3 pages. 18 Nebraska Department of Environmental Quality (NDEQ). 1999. Ground Water Section. Wellhead Protection Program. Wellhead Protection Area Map. 2 pages.7 SITE SUMMARY

The PCE Southeast Contamination site is a ground water plume with no identified source resulting from multiple possible sources associated with past and present commercial and industrial operations near the
intersection of North Lincoln Avenue and 5 th Street in York, Nebraska (see Figures 1 and 2 ; 16, pp. 1-4).
North Lincoln Avenue is the east

- west division for city streets; 5th Street is near the central portion of the City of York, Nebraska. The approximate geographic coordinates for the PCE Southeast Contamination plume site are 40o 51’ 34.54 ” North and 97o 34’ 50.21 ” West, which is nor th of the York Municipal Well # 77-4, located on the north side of West Nobes Road (Road 12) between Blackburn Avenue and South Delaware Street (Figures 1 and 2).

The site is composed of documented releases of hazardous substances, consisting of the vola tile organic compounds (VOCs) tetrachloroethene (PCE) and trichloroethylene (TCE) into ground water, and detected
in wells associated with the local public drinking water supply and private residences (Ref. 5, pp. 5-6; 23, p. 165; Section 2.2.1 of th is Haz ard Ranking System [HRS] documentation record). The driving factor
for the HRS site score is drinking water targets that are subject to actual contamination. Recent EPA site investigations have documented VOCs in private drinking water wells at concentrations that exceeded the Cancer Risk (CR) screening concentrations and Maximum Contaminant Levels (MCL) (Ref. 2, p. 5). In addition, a public water well (well 77 -4) sample collected by the U.S. Geological Survey (USGS) for its published 2008 Scientific Investigation Report documented PCE in the well at a concentration of 4.56 μg/L (Ref. 9, pp. 21, 133).8 2.2 SOURCE CHARACTERIZATION

E PA has conducted several investigations at this site since January of 2010. To date, EPA conducted an
Abbreviated Preliminary Assessment dated January 19, 2010 , a Site Inspection / Removal Site Evaluation dated February 16, 2012 , and an Integrated Site Assessment dated February 14, 2012 in order to
determine the concentrations and extent of contamination, and identify possible source areas.

2.2.1 SOURCE IDENTIFICATION

Name of source: - Southeast York Area Ground Water Plume (with no identified source)
Number of sources : - 1 Source Type : - Contaminated ground water plume Description and Location of Sources (with reference to a map of the site): Figure 1

Source 1 encompasses an area of VOC -contaminated ground water – with PCE as the primary
contaminant of concern but also TCE – including a public supply well , numerous private domestic drinking water supply wells , monitoring wells, and temporary wells in the York area ( Refs. 4, pp.67-68).
I t is not possible to identify and associate the ground water plume with any specific source(s) of the
contamination at this time . Therefore, the source has been identified as a ground water plume with no
identifiable source.

The site consists of a PCE and TCE contaminated ground water plume , which are contaminants commonly associated with local historical industrial and commercial use. Analytical results have
identified e levated levels of these contaminants in ground water; however, the extent of contamination has not been fully characterized (Ref. 4, pp. 21-27, 46-47, 69; 6, p. 18). The estimated center location of operations that resulted in the contaminated plume is annotated on the York, Nebraska U.S. Geological Survey 7.5-minute quadrangle maps ( Ref. 3; 1).

In 2010, an Abbreviated Preliminary Assessment ( APA ) was conducted by EPA

. Private wells at four
residences had PCE levels exceeding health

- based benchmarks (Ref. 6, pp. 11-12). The more recent EPA
CERCLA assessment s associated with the site are the 2012 RSE/SI and 2012 Integrated Site Assessment (ISA) Report. Combined investigations from EPA indicated an area

- wide ground water pl ume and some soil contaminatio n, which are associated with local industrial and commercial operations (Ref. 4, p. 6, 8, 14 5, pp. 6, 7). During the RSE/SI, PCE (ranging from 6.1 to 46 μg/L) was identified in six private wells, all exceeding the MCL. TCE was also detected the same six wells, with concentrations ranging from 0.89 to 8.0 μg/L. One well, which also contained a PCE concentration of 21μg/L, was across the street from
the location where TCE had exceeded the MCL in 2010 (Ref. 4, pp. 26-27). During the ISA, PCE and its9 degra dation products TCE, ci s -1,2-DCE, and vinyl chloride were detected in temporary well (TW) ground water samples collected near and downgradient of former dry cleaners or laundries operating near W.
5 th Street and N. Lincoln Avenue. PCE was detected at a maximum concentration of 280 μg/L in the ground water sample collected at 31 to 35 feet bgs at TW-20, located near the southeast (downgradient) corner of the former dry cleaners property at 423 N. Lincoln Avenue. The sample from 46 to 50 feet bgs
at TW -20 contained 16 μg/L of PCE. PCE was also detected at 5.3 μg/L in the 31 - to 35-foot bgs sample
from TW -21, and at 73 μg/L in the 31- to 35-foot bgs sample from TW- 27. These sample locations were
about 150 feet west- northwest and 160 feet northwest of TW -2 0, respectively (Ref. 5, pp. 15-20, 40).

EPA has performed studies in attempt to characteriz e the extent of the ground water contamination and
has identified multiple possible industrial and commercial sources

. Elevated levels of PCE and TCE have
been d etected in drinking water wells on multiple occasions between 2010 and 2012 (Ref. 4, p. 6, 8, 14; 5, pp. 6, 7).

HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

The ground water plume source hazardous substances are those hazardous substances for which an

o bserved release has been established. The contaminant s of concern associated with the site used for scoring purposes are PCE and TCE . The results presented below from historical ground water sampling

events document elevated levels of PCE and TCE at the site.

Background Levels
Public Supply Well
Nebraska Department of Health and Human Services (NDHHS) data for public water supply well 77 -3,
located upgradient and about 1.5 miles northwest of public water supply well 77 -4, indicate no VOCs in 77-3 when sampled on September 6, 2005, September 8, 2008, and August 29, 2011 (8, pp. 1-9; 13, p. 33 ). Well 77 -3 is not downgradient of possible sources; therefore it was selected as an appropriate background sample for co mparing release samples collected from the public water supply (Ref. 5, pp. 25-26; 7, p. 25).10 Table 1: Source Background Samples for Municipal Well Samples Laboratory Sample Number Well ID Dates Collected Analyte Concentration (μg/L) MDL (μg/L) Well Depth (ft bgs) Screened Intervals

(ft bgs) References P28022

- 169 York PWS 77 -3 a 09/06/2005 PCE TCE 0.5 U 0.5 U 0.14 0.19 292 150

- 205 272

- 292 Ref. 4, p. 48; 8, pp. 1 -9 ; 13, p. 33 P34394

- 167 09/08/2008 PCE TCE 0.5 U 0.5 U 0.14 0.19 117905 08/29/2011 PCE TCE 0.5 U 0.5 U 0.14 0.19

Notes:
* Because these samples were analyzed using EPA Method 524.2, the MDLs are provided. As per the method, MDLs are sufficient to detect analytes at the required levels according to the Safe Drinking Water Act regulations (Ref. 13, pp. 15

- 16 ).

a See Figure s 1 and 2 for location of sample included in Table 1. ID Identification μg/L micrograms per liter U The analyte was not detected (the value next to “U” in the concentration column represen ts the method detection limit) ft bgs feet below ground surface

Private Wells
A dedicated background sample (Sample Number 5432-10) was collected by EPA in August 2011 and analyzed for VOCs (Ref. 4, pp. 26, 69). The sample listed in Table 2 was collected from private well and

serve s as a background for comparison to other private wells at the site. The background residential well

was selected from an area that is generally upgradient and away from the contaminated wells ( Ref. 4, p. 69). Although well construction information is not available, most of the residential wells that met the observed release criteria are expected to draw drinking water from the same aquifer interval (Ref. 4, p. 47). The background sample was collected using the same sampling plan as release samples associated
with Analytical Services Request ( ASR ) 5432 (Ref. 4, pp. 1, 23-27, 14, pp. 1, 8-9, ).11 Table 2: Source Background Samples for Private Well Samples

Laboratory Sample ID 1 , 2 Sampling Date or Analyzed Date Hazardous Substance Hazardous Substance Concentration (μg/L) Method Detection

Limit Well Depth (ft bgs) References

5432

- 10 08/10/11 PCE 0.5 U 0.14 Unknown Ref. 4, pp. 123, 175, 299, 308

- 309 TCE 0.5 U 0.19 Unknown

Notes:

1 This sample was analyzed for VOCs using EPA Region 7 Method 3230.09, which meets the requirements of EPA Method 524.2 (Ref 14, p. 8). The MDLs are provided. As per the method, MDLs are sufficient to detect analytes at the required levels according to the Safe Drinking Water Act regulations (Ref. 13, pp. 15

- 16). 2 See Figure s 1 and 2 for the location of sample included in the table. ID Identification μg/L micrograms per liter U The analyte was not detected (the value next to “U” in the concentration column represents the method detection limit) ft bgs feet below ground surface

Contaminated Samples
The ground water pathway source hazardous substances are those hazardous substances for which an
observed release was established wi thin the evaluated aquifer. PCE was detected in public water supply
well 77 -4 on two known occasions since 2004 (Ref. 9, pp. 23, 133).

As noted earlier, of a total of seven residential ground water well samples collected by EPA in support of
the York RSE/SI , 5 (71 percent) contained PCE above the MCL of 5 μg/L . In addition, one private well sample (5349-1) collected in April 2011 in support of the EPA ISA and four private well samples (5105-3, 5105-17, 5105-18, and 5105-19 ) collected near the intersec tion of Road N and Road 12 (E. Nobes Road) in November 2010 in support the EPA APA contained PCE concentrations above MCL. Because the most immediate health threat is deemed to be contaminated ground water used for drinking,
EPA has planned supply of alte rnative water to residents with private wells contaminated with VOCs at concentrations above regulatory action levels (Ref. 5, pp. 196-197).12 Table 3: Contaminated Wells

Laboratory Sample Number C Sampling Date or Analyzed Date Hazardous Substance Hazardous Substance Concentration (μg/L) Method Detection

Limit a (μg/L) Well Depth (ft bgs) Reference Study PWS Well, Depth 48.8 meters 06/17/2004 PCE 2.38 See Notes a 141

– 200 b Ref. 9, pp. 23, 133 Study PWS Well, Depth 51.8 meters 06/17/2004 PCE 4.56 See Notes a Ref. 9, pp. 23, 133 5349

- 1 04/26/2011 PCE TCE 46 4.9 0.14 0.19 Unknown Ref. 5, pp. 39, 67

- 68, 116, 120, 5432

- 1 08/09/2011 PCE TCE 6.1 2.0 0.14 0.19 Unknown Ref. 4, pp. 26, 69, 124, 166, 299, 304

- 305 5432

- 2 08/09/2011 PCE TCE 21 8.0 0.14 0.19 Unknown Ref. 4, pp. 26, 69, 124, 167, 299, 304

- 305 5432

- 3 08/09/2011 PCE TCE 8.2 0.89 0.14 0.19 Unknown Ref. 4, pp. 26, 69, 124, 168, 299, 304

- 305 5432

- 4 08/09/2011 PCE TCE 11 1.5 0.14 0.19 Unknown Ref. 4, pp. 26, 69, 124, 169, 299, 304

- 305 5432

- 9 08/10/2011 PCE TCE 12 3.8 0.14 0.19 Unknown Ref. 4, pp. 26, 69, 124, 174, 299, 308

- 309 5105

- 1 10/11/2010 PCE TCE 0.59 0.50 U 0.14 0.19 Unknown Ref. 6, pp. 9, 42, 75

- 76 5105

- 3 10/11/2010 PCE TCE 12 5.9 0.14 0.19 Unknown Ref. 6, pp. 9, 44, 75

- 76 5105

- 17 10/13/2010 PCE TCE 30 0.88 0.14 0.19 Unknown Ref. 6, pp. 10, 58 5105

- 18 10/13/2010 PCE TCE 22 1.4 0.14 0.19 Unknown Ref. 6, pp. 10, 59 5105

- 19 10/13/2010 PCE TCE 22 2.1 0.14 0.19 Unknown Ref. 6, pp. 10, 60

Notes:

a This sample was analyzed for VOCs using EPA Region 7 Method 3230.09, which meets the requirements of EPA Method 524.2 (Ref 14, p. 8). The MDLs are provided. As per the method, MDLs are sufficient to detect analytes at the required levels according to the Safe Drinking Water Act regulations (Ref. 13, pp. 15

- 16). b In June 2004, USGS collected ground water samples for various intervals within the screened interval (140

- 200 feet bgs) at the PWS Study Well (identified by its location as well 77 -4) . Samples were collected using a 1

- inch

- diameter bladder pump lowered through a 1.5

- inch polyvinyl chloride (PVC) pipe that had been installed to 140 feet bgs. USGS samples were identified by the pump depth and assumed to represent water from that depth and below. This data was published as a Scientific Investigations Report (2008

- 5050) by the USGS (Ref. 9 , pp. 133)

c See Figure s 1 and 2 for location of samples included in Table 3. PWS Public Water Supply μg/L micrograms per liter ft bgs feet below ground surface USGS Unites States Department of the Interior, U.S. Geological Survey13 3.0.1 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Table 4: Containment Factor Value

Containment Description Containment Factor Value Reference Gas release to air Not Scored NA Particulate release to air Not Scored NA The containment factor value for the ground water migration pathway was evaluated for “All Sources” for evidence of hazardous substance migration from source area (i.e, source area includes source and any associated containment structures). The source is a ground water plume. The plume is defined as an area of contamination released to ground water and detected in ground water samples. Applicable containment factor value was determined based on existing analytical evidence of hazardous substances in ground water samples from private and public wells. Therefore, the highest ground water migration pathway containment factor value of 10 was assigned to Source Number 1 as specified in Table 3

- 2 of the HRS (R ef. 1, Section 3.1.2.1). 10 Ref. 7, pp. 46

- 48, 30

- 32; 5, pp. 30

- 32; 6, pp. 8- 9, 20

Release via overland migration and/or flood. Not Scored NA14 2.2.3 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 H azardous Constituent Quantity
The hazardous constituent quantity for Source No. 1 could not be adequately determined according to the HRS requirements; that is, the total mass of all CERCLA hazardous substances in the source is not known
and cannot be estimated with reasonable confiden ce [Ref. 1, Section 2.4.2.1.1 ]. There are insufficient historical and current data (Manifests, PRP records, State records, permits, waste concentration data, etc.) available to adequately calculate the total mass of all CERCLA hazardous substances in the source and the associated releases from the source. Therefore, there is insufficient information to evaluate the associated releases from the source to calculate the hazardous constituent quantity for Source No. 1 with
reasonable confidence. Hazardous Co nstituent Quantity Value: Not Scored

2.4.2.1.2 Hazardous Wastestream Quantity
The hazardous wastestream quantity for Source No. 1 could not be adequately determined according to the HRS requirements; that is, the total mass of all hazardous wastestreams and CERCLA pollutants and contaminants in the source is not known and cannot be estimated with reasonable confidence [Ref. 1,
Section 2.4.2.1.2 ]. There are insufficient historical and current data (Manifests, PRP records, State records, permits, etc.) available to a dequately calculate the total mass of all hazardous wastestreams and CERCLA pollutants and contaminants in the source and the associated releases from the source. Therefore, there is insufficient information to evaluate the associated releases from the so urce to calculate the hazardous wastestream quantity for Source No. 1 with reasonable confidence. Hazardous Wastestream Quantity Value: Not Scored

2.4.2.1.3 Volume
For the migration pathways, the source is assigned a value for volume using the appropriate Tier C equation from Table 2-5 (Ref. 1, Section 2.4.2.1.3). Because the extent of the ground water plume is unknown, the volume for the ground water plume will be designated as unknown, but contaminated ground water samples are present , so the quantity is greater than zero.

Volume: >0

2.4.2.1.4 

### Area
The area measure (Tier D) is not evaluated for source type “other” (Ref. 1, Table 2 -5).

Area: 015 2.4.2.1.5 Sou rce Hazardous Waste Quantity Value
Highest assigned value assigned from Table 2 -5: >016 Table 5: S ummary of Source Descriptions

Source No. Source Hazardous Waste Quantity Value Source Hazardous Constituent

Quantity Complete? (Y/N) Containment Factor Value by Pathway Ground Water (GW) (Table

3- 2) Surface Water (SW) Air

Overland/flood

(Table 4- 2) GW to SW (Table

3- 2) Gas (Table

6- 3) Particulate (Table

6- 9) 1 >0 No 10 Not Scored Not Scored Not Scored Not Scored

Other Possible Sources
There are many possible sources resulting from various operations such as dry cleaners ( who o ften use tetrachloroethene [PCE]) and metal degreasing operations ( who often use PCE or TCE)(Ref. 4, pp. 6-7; 5, pp. 5-6; 16, pp. 1-4). E arliest documented dry cleaning operation in the site area dates back to 1948 . A
list of known operations and facilities are d iscussed further in subsequent paragraphs

.
A dry cleaner (Deluxe Cleaners) is located at 609 N. Lincoln Avenue in downtown York. Historical city directories indicate this dry cleaners has been at this address since at least 1948 (oldest City directory available at the York Public Library). This address was shown as a storefront on 1933 and 1946 Sanborn

maps (Ref. 4, pp. 386-387) . Review of historical Sanborn Fire Insurance Maps and York city directories indicated that laundries, steam laundries, or dry cleaners were formerly located at 107 E. 6 th Street (Foster Cleaners/Valet Cleaners, c. 1948 -1961), 116 W. 7 th Street (York Laundry and Dry Cleaners,

c. 1960-1970), and 827 N. Lincoln Avenue (H&H Cleaners and Shirt Launderers, c. 1984-1991) (Ref. 4, pp. 39-42, 383-397). PCE was identified in a soil sample collected from 1 -3 feet bgs at SB 4, located north of (behind) a former dry cleaner building at 107 E. 6th Street in downtown York (Ref. 4, pp. 13-14).

Sanborn Fire Insurance Maps for 1933 and 1946 (updated 1933 map) indicate that a dry cleaner was also located at the western part of the lot at 423 N. Lincoln Avenue; a storefront building faced Lincoln Avenue at the eastern portion of the lot (Ref. 4, pp. 384, 386-387). These Sanborn maps indicate t hat buried solvent tanks were located along the alley west of the property. A 1915 Sanborn map indicates the western building was for “clothes cleaning” and the eastern storefront was for a tailor. Review of the York telephone directories at the York Pub lic Library indicated that Blair Cleaners (formerly Olson Cleaners) was located at that address in 1948 (Ref. 4, pp. 12-13). The next available directory (1963) indicated a jewelry store was located at the address. Various jewelry stores were listed at the address through 1990 (Ref. 4, pp. 13) . The storefront building is currently a law office, and the area where the western building had been located is gravel covered. A movie theatre is to the north; private parking lots
are located to the south and ac ross the alley to the west. A gas station had been previously located at the17 northwest parking lot (southeast corner of W. 6 th Street and N. Platte Avenue). The 1963 York city directory indicated an Econowash Laundromat was located at 508 N. Platte Avenu e (north of the former gas station). This former laundromat, currently part of Chances R restaurant, may have had coin-operated dry cleaning machines (Ref. 4, pp. 12-13).

A list of EPA

- regulated facilit ies in the Envirofacts database is presented as Ref erence 16.18 3.0 GROUND WATER MIGRATION PATHWAY

3.0.1 GENERAL CONSIDERATIONS
The site is situated in the High Plains aquifer area of Nebraska where Quaternary and undivided Tertiary units are present. Quaternary alluvial deposits of the High Plains aquifer p rovide ground water to wells in the area. This aquifer consists of fluvial sands, gravels, silts, and clays . The uppermost layer consists of unsaturated loess having a maximum thickness of about 88 feet in the York area. Below that is a
maximum of about 140 feet of sand and gravel, with some lenses of silt and clay. The following paragraphs present a summary of the stratigraphy described by USGS and information for two deep USGS monitoring wells in the southern York area. USGS investigations in this are a are discussed below.

Ground Water Migration Pathway Description

The upper portion of the aquifer has an average thickness of 68 feet and a maximum thickness of 140 feet

. It underlies loess and is composed of sand and gravel, with some lenses of silt and clay. The water table occurs near the top of these sands and gravels. Typically, silts and clays and finer sands and gravels increase with depth in this layer (Ref. 7 p 9). This portion of the aquifer has a hydraulic conductivity of approximately 136 feet /day ( Ref 7, p p 1 1, 13 ).

Below t he sand and gravel is a silt deposit which acts as a sem i-confining layer. Below the silt deposit is a clayey glacial till that is water bearing and producible. Below the c layey glacial till is another silt layer
which acts as a semi

- confining layer. Below the silt layer is about 80 feet of fine - to medium-grained sand, with minor amounts of gravel. Nearly all PWS wells and many irrigation wells in the area are fully

scree ned across this sand and the hydraulic conductivity of this sand is approximately 65 feet/day Underlying this sand aquifer is a layer consisting of about 105 feet of silts and clays with some
interbedded sands (Ref. 7, pp. 9-14). While this aquifer consists of many layers, evidence of contamination migration (as discussed below via leaky boreholes (Ref. 15 p. 35)), and ground water sample results demonstrate that any semi -confining or confining layers present are not functioning competent or impermea ble barriers to ground water/contaminant flow in the site vicinity; thus the aquifer beneath the site is, for HRS scoring purposes, considered equivalent to a single interconnected aquifer system (Ref. 1, Section 3.0.1.2.2).

USGS installed monitoring wells in the various aquifer layers as part of its investigation s into ground

water flow and contamination in the York area (Ref. 15, pp1-58). These monitoring wells were sampled for VOCs several times between 2003 and 2005, and a number of wells contained PCE and TCE (Ref. 15, pp. 133-165 ). Monitoring well FP1 -63, located adjacent to PWS well 77 -4, contained PCE (0.42 μg/L),19 TCE (0.27 μg/L), and cis -1,2-DCE (0.16 μg/L) in samples from 242- 247 feet bgs —the lower portion of the aquifer (Ref. 9, p.133)

.

USGS al so collected ground water samples every 10 feet within the screened interval ( 140 -200 feet bgs )
at PWS well 77 -4 . Samples were collected using a 1 -inch-diameter bladder pump lowered through a 1.5-inch polyvinyl chloride (PVC) pipe plac ed to the top of the screen at 140 feet bgs (Ref. 9, p. 29)

. USGS detected PCE, TCE, and cis -1,2- DCE at all five depths; however, the highest concentrations of PCE (4.56 μg/L) , TCE (3.2 μg/L) , and cis -1,2-DCE (1.81 μg/L) were detected in the ground water sample from 170 feet bgs (Ref. 9, p. 133).

Based on isotope s in the samples, USGS concluded that the ground water entering the deeper portion of
PWS well 77

- 4 well screen derived from the upper portion of the aquifer. Because isotopes from samples
collected from the upper portion of the screened interval did not match those in the lower, USGS
concluded that the flow from the u pper portion of the aquifer was not through the well bore for PWS well 77-4, but was likely occurring from downward leakage through well bores or annular spaces of irrigation, commercial, or older supply wells that penetrated both these layers ( Ref. 9, p. 16 ). USGS identified
numerous wells and test holes in the York area that were leakin g (Ref. 15 p. 35). Further, there are no known discontinuities that transect the entire 4 mile Target Distance Limit (TDL).20 3.1 LIKELIHOOD OF RELEASE

3.1.1 O BSERVED RELEASE
Aquifer Being Evaluated: Interconnected Aquifer

Chemical Analysis
Establishing an observed release by chemical analysis requires analytical evidence of a hazardous substance or substances in the media significantly above background level. If the background concentration is not detected (or is less than the detection limit), an observed release is established when the sample result equals or exceeds the detection limit (Ref. 1, p. 51589). None of the background samples exhibited any detectable concentration of PCE or TCE. Numerous ground water samples
collected from public and private drinking water wells have been found to contain VOCs, particularly
PCE and TCE . Tables 1 and 2, and Table 3 in the Source Identification Section 2.2.1 depict the background and release samples used to document an observed release by chemical analysis . Based on the background well and release well sample results presented in the Hazardous Substances Associated with the Source section tables, observed release criteria have been met.

Attribution
The PCE Southeast Contamination site area has had numerous commercial and industrial operations that currently and historically have handled PCE and TCE . Nine such locations were identified during the 2010 APA conducted by EPA (Ref. 6, pp. 5-6).

The PCE Southeast contamination was entered into the C ERCLIS in May 2010, after an EPA
Pre

- CERCLIS Site Screening report had identified the potential for contamination from industries in the area ( Ref. 4, pp 6-7). The Pre

- CERCLIS sampling identified VOCs - including PCE and TCE - in five private wells

. Thes e wells were located within 0.25 mile north or south of E. Nobes Road, between
S. Iowa Avenue in southeastern York and Road N, located about 0.75 mile east of the York city limits.
The wells associated with another site, the York PCE site , are about 0.4-1 .4 miles east of the contaminated wells associated with the Southeast York Groundwater site. The investigation areas for the two sites overlapped along E. Nobes Road (Road 12). Figure 2 in Appendix A of Reference 4 presents an overview of these approximate site areas (Ref. 4, p. 67).

PCE is commonly used as a dry cleaning solvent or in metal degreasing, and contamination at both sites likely derived from the same general area —commercial or industrial areas of York, located about 0.5 to
2 miles northwest ( upgradient). TCE is also commonly used in metal degreasing but is also a common21 daughter product of PCE degradation; cis -1,2 -DCE and vinyl chloride are common daughter products from degradation of TCE.

EPA requested START to conduct investigations at bo th sites. Because similar PCE concentrations were detected at both the sites, it was uncertain whether the ground water contamination was attributable to releases from multiple sources, multiple releases from a single source area, or a combination of the two.

In April 2011, START collected ground water samples from additional private wells near the York PCE site, including one in the area where the two site investigations overlap. Because of the similarity of the York PCE site to the Southeast York Groundwater site, direct-push technology (DPT) investi gations to identify the source areas for the ground water plumes were combined under the Southeast York
Groundwater site. Comparison of results between the York PCE site and the PCE Southeast Contamination site indicate that the plume associated with the former site does not contain TCE, whereas the latter site contains pronounced TCE concentrations alongside PCE (Ref. 4, pp. 15, 21-23). On this basis, the two sites are considered separate and the PCE Southeast site is the subject of this HRS
documentation record.

Hazardous Substances Released : PCE, TCE

Ground Water Observed Release Factor Value: 550

3.1.2 POTENTIAL TO RELEASE

Not Evaluated

.22 3.2 WASTE CHARACTERISTICS

3.2.1 T OXICITY/MOBILITY

Table 7: Toxicity/Mobility Factor Table

Hazardous Substance Source No. Toxicity Factor Value Mobility Factor Value 1 Does Haz. Substance Meet Observed Release? (Y/N) Toxicity/ Mobility (Table 3

- 9) Reference PCE TCE 1 1 100 1,000 1 1 Yes Yes 100 1,000 2, p p

. 2

- 3 2, pp. 4

- 5

Notes:
1. As per HRS Section 3.2.1.2 (Ref. 1, p. 51681), a mobility factor of 1 is assigned to each hazardous substance that meets the criteria for an observed release by chemical analysis.
Toxicity/Mobility Factor Value: 1,000 (Ref. 1, Table 3- 9)

3.2.2 HAZARDOUS WASTE QUANTITY

Table 8: Source Hazardous Waste Quantity
Source No. Source Type Source Hazardous Waste Quantity 1 Ground Water Plume with no identified Source > 0, but unknown

The HRS states that if the hazardous constituent quantity is not adequately determined for one or more

sou rces then assign a factor value of 100 if any target for that migration pathway is subject to Level I or Level II (Ref. 1, Section 2.4.2.2). As there are Level I targets for this pathway (see Section 3.3 of this document), 10 0 will be assigned as the hazardous waste quantity factor value.

Sum of Values: > 0 Hazardous Waste Quantity Factor Value: 100 (Ref. 1, Table 2-6

3.2.3 WASTE CHARACTERISTICS FACTOR CATEGORY VALUE
As specified in the HRS (Ref. 1, Section 3.2.3), the Hazardous Waste Quantity Factor Value of 100 is multiplied by the highest toxicity/mobility value of 1,000 for TCE, resulting in a product of 100,000 (1.0E+05). Based on this product, a waste characteristics factor value (WCFV) of 18 is assigned from
Table 2 -7 of the HRS (Ref., Section 2.4.3.1).

Toxicity/Mobility Factor Value: 1,000 Hazardous Waste Quantity Factor Value: 100
Toxicity/Mobility Factor Value X Hazardous Waste Quantity Factor Value: 100,000 Waste Characteristics Factor Category Value: 18 (Table 2- 7)23 3.3 TARGETS

3.3.1 N EAREST WELL
The following well contains contamination that mee ts the observed release criteria, and the PCE
concentration is above the health -based benchmark of 5 μg/L (MCL/MCLG) (See Section 3.1.1 of this document; Refs. 1, Table 2-3, 3-10; 2, p. 9).

Well ID: 5105-17 Level of Contamination (I, II, or potential): I

Nearest Well Factor Value: 50 (Ref. 1, Table 3-11; Section 3.1.1 of this document)

3.3.2 POPULATION

3.3.2.1 Level of Contamination

3.3.2.2 Level I Targets (concentrations associated wi th Level I targets are presented in Section 3.1.1 of this document )
A Level I sample is defined as a drinking water sample with concentration of a hazardous substance such

as PCE and TCE that meets the criterion of an observed release at or above the hazardous substance’s drinking water benchmark (Ref. 1, Section 2.5.1). Health-based benchmarks for the ground water migration pathway include the maximum contaminant level (MCL), the cancer risk screening concentration (CRSC), and the Non Cancer Risk screening concentration (NCRSC) (Ref. 1, Table 3-10). The EPA has set the following health

- based benchmarks for TCE and PCE :

• For PCE , MCL is 5 μg/L , CRSC is 32 μg/L , and NCRSC is 94 μg/L (Ref. 2, pp, 2, 3 ).

• For TCE, MCL is 5 μg/L , CRSC is 1.0 μg/L , and NCRSC is 7.8 μg/L (Ref. 2, pp, 4, 5)
The following targets obtain drinking water from wells that contained one or more analytes at
concentrations that meet the observed release criteria and are above health

- based benchmarks (Ref. 1,
Table 2 -3, Table 3-10, and Section 3.1.1).24 Table 9: Level I Samples and Targets Laboratory Sample Number 2 Hazardous Substance Hazardous Substance Concentration (μg/L) Population Served 1 Aquifer Reference 5349

- 1 PCE TCE 46 4.9 2.25 1 Ref. 5, pp. 39, 67

- 68, 116, 120; 10, pp. 1

- 2 5432

- 1 PCE TCE 6.1 2.0 2.25 1 Ref. 4, pp. 26, 69, 124, 166, 299, 304

- 305; 10, pp. 1

- 2 5432

- 2 PCE TCE 21 8.0 2.25 1 Ref. 4, pp. 26, 69, 124, 167, 299, 304

- 305; 10, pp. 1

- 2 5432

- 3 PCE TCE 8.2 0.89 2.25 1 Ref. 4, pp. 26, 69, 124, 168, 299, 304

- 305; 10, pp. 1

- 2 5432

- 4 PCE TCE 11 1.5 2.25 1 Ref. 4, pp. 26, 69, 124, 169, 299, 304

- 305; 10, pp. 1

- 2 5432

- 9 PCE TCE 12 3.8 2.25 1 Ref. 4, pp. 26, 69, 124, 174, 299, 308

- 309; 10, pp. 1

- 2 5105

- 3 PCE TCE 12 5.9 2.25 1 Ref. 6, pp. 9, 44, 75

- 76; 10, pp. 1-2 5105

- 17 PCE TCE 30 0.88 2.25 1 Ref. 6, pp. 10, 5; 10, pp. 1

- 28 5105

- 18 PCE TCE 22 1.4 2.25 1 Ref. 6, pp. 10, 59; 10, pp. 1

- 2 5105

- 19 PCE TCE 22 2.1 2.25 1 Ref. 6, pp. 10, 60; 10, pp. 1

- 2

Notes:

1 The average persons per household for the City of York, Nebraska has been used (Ref. 10, pp. 1

- 2)

. 2 See Figure s 1 and 2 for location of samples included in Table 9. μg/L Micrograms per liter Sum of Population Served by Level I Wells: 22.5

Sum of Population Served by Level I Wells: 22.5 Sum of Population Served by Level I Wells x 10: 225.00 Level I Concentrations Factor Value: 225.00

3.3.2.3 Level II Targets (concentrations associated with Level II targets are presented in Section 3.1.1)
The following targets obtain drinking water from wells that contained one or more analytes at
concentrations that meet the observed release criteria and are not above an HRS health

- based benchmark (Ref. 1, Table 2

- 3, Table 3 -10, and Section 3.1.1).25 Tabl e 10: Level II Samples and Targets

Sample ID Number or Well Number Hazardous Substance Hazar d Substance Concentration (μg/L) Population Served Aquifer Reference 77

- 4 PCE 4.56 425 a 2 Ref. 9, pp. 23, 133 ; 17, pp. 1

- 2 5105

- 1 PCE TCE 0.59 0.50 U 2.25 b 1 Ref. 6, pp. 9, 42, 75

- 76; 10, pp. 1

- 2

Notes:

a Based on a population of 8,081 served by 19 active PWS wells (denoted as “A” in the referenced database), a population of 425 was assigned to each well. The two emergency use wells are included in the 19 act ive wells (Ref. 4, p. 50; 17, p. 2 -3 ). b The average persons per household for the City of York, Nebraska has been used (Ref. 10, pp. 1 -2).

c See Figure s 1 and 2 for location of samples included in Table 10. ID Identification Sum of Population Served by Level II Wells: 427.25

Sum of Population Served by Level I I Wells: 427.25 Sum of Populat ion Served by Level II Wells x 1 : 427.25 Level I I Concentrations Factor Value: 427.25

3.3.2.4 Potential Contamination

Not Scored

.

3.3.3 RESOURCES

Not Scored

.

3.3.4 WELLHEAD PROTECTION AREA
A designated Wellhead Protection Area for the York public water supply system has been mapped within
the 4- mile target distance limit (Ref. 18, pp. 1-2). The maps provided in Reference 18 are based on the
Wellhead Protection Area Based on 20- year Time -of- Travel. In accordance with Section 3.3.4 of
R eference 1, because a source with a ground water containment factor value greater than 0 lies within or above the designated Wellhead Protection Area, a value of 20 is assigned and entered below and on line
10 of HRS Table 3-1.

Wellhead Protection Area Factor Value: 20