### COVER SHEET

SITE NAME: Iowa

- Nebraska Light & Power Co

EPA ID No. NED986373678

Contact Persons

EPA Contact : Preston Law U.S. Environmental Protection Agency (EPA), Region 7 11201 Renner Blvd. Lenexa, Kansas 66219 (913) 551

- 7 0 97

Documentation Record: David Zimmermann, Tetra Tech START

Pathways, Components, or Threats Not Scored

The air migration pathway, soil exposure pathway, and surface water migration pathway were not scored as part of this Hazard Ranking System (HRS) e valuation. These pathways or components were not included because a release to these media does not significantly affect the overall site score and because the ground water migration pathway alone produces an overall site score well above the minimum
requ ired for the site to qualify for inclusion on the National Priorities List (NPL). These pathways are of concern to EPA and may be evaluated during future investigations.

### 1 HRS DOCUMENTATION RECORD

Name of Site: Iowa

- Nebraska Light & Power Co

EPA Region: 7

Date Prepared: September , 2015

Street Address of Site * : 102

- 104 South 7 th 

### Street (Ref. 33)

City, County, State , ZIP : Norfolk, Madison County , Nebraska , 68701 (Ref. 33)

General Location in the State: The site is located in the northeastern portion of Nebraska, about 115 miles northwest of the Omaha metropolitan area (Ref. 5, p. 5) (Figure 1).

Topographic Map: The location of the INL&P Site is shown on the Norfolk, Nebraska, Quadrangle, U.S. Geological Survey, 7.5

- Minute Series Topographic Map (Ref. 3).

Latitude: 42 o 

### 01' 56.28 " N. (Ref. 4)

Longitude: 97 o 

### 25' 01.30 " W. (Ref. 4)

The latitude and longitude listed above is the approximate geographic location as measured from within the area of contaminated soil (Source 1) , specifically within the gas holder on the facility property (Ref. 4 ; Figure 2 of this HRS document ation record ).

Scores

Ground Water Migration Pathway 81. 60 Surface Water Migration Pathway Not scored Soil Exposure Pathway Not scored Air Migration Pathway Not scored

HRS SITE SCORE 40. 80

* The street address, coordinates, and contaminant locations presented in this HRS documentation record identify the general area the site is located. They represent one or more locations EPA considers to be part of the site based on the screening informat ion EPA used to evaluate 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 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 address ed under the Comprehensive Environmental Response, Compensation, and Liability Act. 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 t he contamination has come to be located.

### 2 W ORKSHEET 

### F OR 

### C OMPUTING 

### HRS S ITE 

### S CORE 

### S S 2



### 1. Ground Water Migration Pathway Score (S gw 

### ) 81. 60 6,6 58.56

2a. Surface Wa ter Overland/Flood Migration Component (from Table 4

- 1, line 30) Not Scored

2b. Ground Water to Surface Water Migration Component (from Table 4

- 25, line 28) Not Scored

2c. Surface Water Migration Pathway Score (S sw 

### ) Enter the larger of lines 2a and 2 b as the pathway score. Not Scored

3. Soil Exposure Pathway Score (S s 

### ) (from Table 5

- 1, line 22) Not Scored

4. Air Migration Pathway Score (S a 

### ) (from Table 6

- 1, line 12) Not Scored

5. Total of S gw 2 

### + S sw 2 

### + S s 2 

### + S a 2 

### 6,6 58

. 56

6. HRS Site Score Divide the value on line 5 by 4 and take the square root 40. 80

### 3 HRS T ABLE 

### 3

- 1

– G ROUND 

### W ATER 

### M IGRATION 

### P ATHWAY 

### S CORESHEET 

### I OWA



### - N EBRASKA 

### L IGHT 

### & P OWER 

### S ITE



### Factor Categories and Factors Maximum Value Value Assigned Likelihood of Release to an Aquif er: 1. Observed Release

................................ ................................ .................. 550 550 2. Potential to Release: 2a. Containment

................................ ................................ ................... 2b. Net Precipitation

................................ ................................ ............. 2c. Depth to Aquifer

................................ ................................ ............ 2d. Travel Time

................................ ................................ .................... 2e. Potential to Release [lines 2a(2b + 2c + 2d)]

................................ . 10 10 5 35 500 NE NE NE NE NE 3. Likelihood of Release (higher of lines 1 and 2e)

................................ .. 550 550

Waste Characteristics: 4. Toxicity/Mobility

................................ ................................ .................. a 10

, 000 5. Hazardous Waste Quantity

................................ ................................ ... a 10 6. Waste Characteristics

................................ ................................ ............ 100 18

Targets: 7. Nearest Well

................................ ................................ ......................... 50 18 8. Population: 8a. Level I Concentrations

................................ ................................ ... 8b. Level II Concentrations

................................ ................................ .. 8c. Potential Contamination

................................ ................................ . 8d. Population (lines 8a + 8b + 8c)

................................ ...................... b b b b Not Scored Not Scored 637 637 9. Resources

................................ ................................ .............................. 5 5 10. Wellhead Protection Area

................................ ................................ ..... 20 20 11. Targets (lines 7 + 8d + 9 + 10)

................................ ............................. b 68 0

Ground Water Migration Sc ore for an Aquifer: 12. Aquifer Score [(lines 3 x 6 x 11)/82,500] c 

### 100 81. 60

Ground Water Migration Pathway Score:
13. Pathway Score (S gw 

### ), (highest value from line 12 for all aquifers evaluated) 100 81. 60

a Maximum value applies to waste characteris tics category b Maximum value not applicable

c Do not round to nearest integer NE Not Evaluated

### 4

### 5 REFERENCES

Reference Number Description of the Reference 1. U.S. Environmental Protection Agency (EPA). Hazard Ranking System (HRS): Final Rule. Titl e 40 of the Code of Federal Regulations (CFR), Part 300; Federal Register

, Volume 55, No. 241. Excerpt. On

- Line Address: http://www.epa.gov/superfund/sites/npl/hrsres/rule/hrs rule.pdf . December 14, 1990. One
page.

2. EPA. Superfund Chemical Data Matrix (SCDM). Excerpt. (Note: A complete copy of SCDM is available at On

- Line Address: http://epa.gov/s uperfund/sites/npl/hrsres/tools/scdm.htm ). June 20 14

. 25 pages.

3. U.S. Geological Survey (USGS). Norfolk (1976), Hoskins (1976), Madison (1976), Enola (1976). One sheet modified by Tetra Tech to show distance rings and municipal well locations.

4. Tetra Tech Inc. (Tetra Tech). Project Note Regarding Latitude and Longitude for the Iowa

- Nebraska Light and Power (INL&P). Prepared by David Zimmermann

, Program Manager

. July 14, 2015

. One page.

5. Tetra Tech. Expanded Site Inspection Report for the Iowa

- Nebraska Light & Power Company Site. Task Order Number 013. March 30, 2001. 237 pages.

6. Ecology and Environment, Inc. (E&E). “Preliminary Assessment of Former Coal Gasification Site.” EPA Region 7 Field Investigation Team, TDD F

- 07

- 9007

- 013, Overland Park, Kansas. December 11, 1990. 14 pages.

7. HDR Engineering, Inc. “Site Investigation Report Former CENTEL, Inc., Manufactured Gas Plant Site, Norfolk, Nebraska.” October 1992. 175 pages.

8. CDM Federal Programs Corporation. “Site Status Determination and Review of Site Investigation Results as Conducted by HDR Engineering for Minnegasco Iowa/Nebraska Light and Power Company Norfolk, Nebraska

. ” Performed under EPA C ontract 6 8

- W9

- 0021, Work Assignment Number 013

- 79ZZ. April 12, 19 93. 26 pages.

9. Brown’s Directory of American Gas Companies, Selected Records for the Subject Site from 1907 through 1957

. 36 pages.

10. State of Nebraska . “Well Logs for Municipal and Irrigation Wells in the Norfolk, Nebraska Area.” Well Registrati on Numbers, G

- 29258, G

- 29259, G

- 49057, G

- 49058, G

49312, G

- 49313, G

- 59331, G

- 70112, G

- 70113, G

- 70114, G

- 70115, G

- 70116, G

- 7308, and G

- 72272. Multiple dates. 95 pages.

11. U. S. Department of Agriculture, Soil Conservation Service. 1984. “Soil Survey of Madison County, Nebraska.” 1984. Excerpt. 11 pages.

12. U.S. Census Bureau. “ Norfolk (city) QuickFacts from the US Census Bureau ,” Accessed on March 25, 2015. On

- Line Address: http://quickfacts.census.gov/qfd/states/31/3134615.html

. Two pages.

### 6 Reference Number Description of the Reference

13. E&E. “Quality Assurance Project Plan for the Expanded Site Inspection Phase I at the Iowa

- Nebraska Light and Power Company Site, Norfolk, Nebraska.” TDD S07

- 9903

- 026, Overland Park, Kansas. February 14, 2000. 82 pages.

14. Reference Number Reserved.

15. E&E. Memorandum with attachments: “Trip Report for Expanded Site Inspection/Remedial Investigation (ESI/RI) Field Work at the Iowa

- Nebraska Light and Power Site, Norfolk , Nebraska.” TDD S07

- 9903

- 026. April 26, 2000. 10 pages.

16. Nebraska Health and Human S ervices ( N HHS) Drinking Water Branch Water System details for the City of Norfolk Water System, Water System Number NE3111910. Accessed on 3/26/2015

. Three page s.

17. NHHS Safe Drinking Information System. Public Water System Facilities and Public Water System Facilit ies Detail for the City of Norfolk Water System, Public Water System ID NE3111910. Accessed on September 27, 2004. 16 pages.

18. Brogden, R obert E., F. Butler Shaffer, and Richard A . Engberg. “Water Resources of Pierce County, Nebraska.” Nebraska Water Survey Paper Number 41. February 1976. Six pages.

19. Edison Electric Institute. “Handbook on Manufactured Gas Plant Sites.” Prepared for Utility Solid Waste Activities Group, Superfund Committee. Cover page, and portions of Chapter 3. September 1984. 32 pages.

20. E&E. Memorandum with attachments: “Trip Report for Site Reconnaissance: Iowa

Nebraska Light and Power Co. Site, Norf olk, Nebraska.” TDD S07

- 9903

- 026. December 30, 1999. Seven pages.

21. State of Nebraska Well Registration System. Database printout of registered wells in Madison County, Nebraska, for Township 23 North, Range 1 West; and Township 24 North Range 1 We st. Dated July 18, 1990. Five pages.

22. Reference Number Reserved.

23. Reference Number Reserved.

24. Education Support Services, Nebraska Department of Education. “Statistics and Facts about Nebraska Schools

, 2013

- 2014.” July 2015

. 10 pages excerpted

. Full report can be found at the found at the following Online Address: http://drs.education.ne.gov/quickfacts/Pages/DistrictandSchoolInformation.aspx?RootFol der=%2Fquickfacts%2FDistric t%20and%20School%20Information%2FStatistics%20and %20Facts%20about%20Nebraska%20Schools&FolderCTID=0x012000308E78E48EF70 A4A969441D8F8732146&View={687391D6

- 980C

- 4AEA

- BA91

- FEF54153E36D}

25. NHHS Safe Drinking Water Branch . Water System Facility Detail W ater System Facility

### 7 Reference Number Description of the Reference Detail for the City of Norfolk Water System, Water System ID Number NE3111910. Accessed on July 29, 2015

. 66 pages.

26. 201 3 Nebraska Higher Education Progress Report. Appendix 1. March 14. . On

- Line Address for full report : http://www.ccpe.state.ne.us/publicdoc/ccpe/reports/progressReport/2012/default.asp

. 9 pages (excerpted and numbered)

.

27. City of Norfolk Nebra ska Water Division Homepage. Water System Overview. Accessed on August 1 7 , 2010. On

- Line Address : http://www.ci.norfolk.ne.us/water/

. One page.

28. Nebraska Department of Natural Resources, Registere d Ground Water Wells Data Retrieval. Search for all wells in Township 24 North, Range 1 West. Processed November 28, 2001. 65 pages.

29. State of Nebraska Source Water Assessment Program. Undated

. The program document can be found at the following On

- Line Address: http://deq.ne.gov/NDEQProg.nsf/OnWeb/SWAP

. 39 page s

.

30. Terracon (Terracon)

. “ Preliminary Subsurface Assessment Report, Unknown

- Norfolk City Wells. Prepared for the Nebr aska Department of Environmental Quality. UG No. 031398

- DB

- 130 0 . May 13, 1998. ” Selected Figures

. Seven pages.

31. Nebraska Department of Environmental Quality (NDEQ)

- Ground Water Unit, Wellhead Protection Program. Letter from Bryant Reynolds, Com pliance Specialist NDEQ to David Zimmermann, Tetra Tech EM Inc., regarding wellhead protection info rmation with attached wellhead protection maps for community systems in and around Norfolk, Madison County, Nebraska. July 28, 2004. Nine pages.

32. NHHS Safe Drinking Water Information System. Water System Details for the Norfolk Regional Center, Public Water System Number NE3111901; Madison County SID #5, Water System Number NE3111912 ; Madison County SID #3

- Sunny Meadow , Water System Number NE3111909; Covid i en (former Kendal Company) , Water System Number NE3150471; and Sleepy Hollow Acres Water System Number NE3111918. Accessed on July 30

, 20 15

. Nine pages.

33. EPA. CERCLIS. Accessed on August 17, 2010. On

- Line Address : http://oaspub.epa.gov/enviro/cerclis_web.report?pgm_sys_id=NED986373678

. Two
pages.

34. Black and Veatch. “Engineering Evaluation/Cost Evaluation (EECA) Site Characterization Report. Iow a

- Nebraska Light and Power Site (Norfolk Former Manufactured Gas Plant Site). Prepared for Centel Corporation.” March 2010. 650
pages.

35. Northeast Community College, Norfolk Campus. Accessed on August 17, 2010. On

Line Address : http://www.northeast.edu/Norfolk/

. One page.

### 8 Reference Number Description of the Reference 36. Tetra Tech Inc . Project Note Regarding Population Verification for Schools and Public Water System in Norfolk, Nebraska. Prepared by David Zimmermann

, Project Manager

. August 21, 2015

. One page

.

37. Black and Veatch. “ EE / CA Investigation Field Sampling Plan. Iowa

- Nebraska Light and Power. Prepared for Centel Corporation. ” June 2007. 56 pages.

38. Black and Veatch. “ Quality Assurance Project Plan. Prepa red for Centel Corporation. ” June 2007. 38 pages.

39. EPA. “ Administrative Settlement and Agreement and Order on Consent for Engineering Evaluation/Cost Analysis. In the Matter of Iowa

- Nebraska Light & Power Site, Norfolk, Madison County, Nebraska, Aquila, Inc., and Centel Corporation, Respondents. ” April 5, 2007. 56 pages.

40. EPA. “ Memorandum Regarding Iowa

- Nebraska Light and Power Manufactured Gas Plant Site, Norfolk, Madison County, Nebraska (SSID NO. A778), Administrative Settlement Agre ement and Order on Consent for Engineering Evaluation and Cost Analysis. ” From Barbara L. Peterson, Assistant Regional Counsel. To Cecilia Tapia, Director, Superfund Division. April 3, 2007. Two pages.

41. NHHS Drinking Water Branch Water System Fa cilities Detail for the City of Norfolk Water System, Water System Number NE3111910. Accessed on August 17, 2010. Two
pages.

42. Agency for Toxic Substances and Disease Registry (ATSDR). Polycyclic Aromatic Hydrocarbons (PAHs): Public Health Stat e ment . August 1995. Accessed on July 14, 2010. On

- Line Address : http://www.atsdr.cdc.gov/PHS/PHS.asp?id=120&tid=25

. Seven pages.

43. Tetra Tech. Record of Telephone Conversation Regard ing the City of Norfolk Water Supply System. To Alicia Shultz, HRS Specialist. From Dennis Watts, Water Supervisor. July 28, 2010. Six pages.

44. EPA. “ Using Qualified Data to Document an Observed Release and Observed Contamination. EPA 540

- F

- 94

- 028, OSWER 9285.7

- 14FS, PB94

- 963311. ” November 1996. 1 8 pages.

45. EPA. HRS Analytical Results Supplement. ASR Number: 539. August 25, 2010. 208
pages.

46. Black and Veatch. “Soil Removal Summary Report. Norfolk, Nebraska, Former Manufactur ed Gas Plant Site . Prepared for Centel Corporation.” May 2015. 873 pages.

47. Tetra Tech. Project Note Regarding Population Verification for Large Employers Served by City of Norfolk Public Water System, Norfolk, Nebraska. Prepared by Jenna Mead, T etra Tech, Inc. August 27, 2015. One page.

### 9 Reference Number Description of the Reference 48. Nebraska Public Power District. Community “Fast Facts” Profiles, Norfolk, Nebraska. 2012. Accessed on August 27, 2015. On- Line Address: http://econdevtools.nppd.com/aedc/fastfacts.asp?city=Norfolk . 11 pages.

### 10 SITE DESCRIPTION

The Iowa

- Nebraska Light & Power Co (INL & P) site consists of a contaminated soil source resulting from forme r gas manufacturing operations and an associated observed release of hazardous substances to shallow ground water as documented in monitoring wells (see sections 2.2 and 3.1.1 of the HRS documentation record). The primary targets scored for the site are mu nicipal and community wells subject to potential contamination and located within 4 miles of the source (see section 3.3.2.4).

INL&P is located in downtown Norfolk, Madison County, Nebraska. The INL&P facility is located on a city block west of 7 th 

### Stree t between Norfolk and Madison Avenues and includes the alley running east

west between 7 th 

### and 8 th 

### Streets. INL&P is roughly divided into two sections: the east ern portion north of the alley, as well as the northeast ern portion of the area south of the al ley (BH Parcel), is currently owned b y Black Hills (BH) ; and the remaining south ern portion of the property (NPPD Parcel)

, owned by Nebraska Public Power District (NPPD) ( Ref s

. 34, p p . 7 , 71, 72 ) ( s ee Figure 1). T he Norfolk Light and Fuel Com pany Manufact ured Gas Plant was constructed between 1903 and 1909. A water gas process was used to manufacture gas. The Central West Service Company purchased INL&P in 1927. In 1931, INL&P purchased the property and switched to a carbureted water gas process. In Fe bruary 1945, the property was purchased by the Central Electric and Gas Company, but ceased operations before the end of the decade (Ref s . 6, p. 3 ; 34, p. 8 ). In 1941

, NPPD acquired the property from Central Electric and Gas Company, excluding those porti ons of the property where manufactured gas plant ( MGP ) operations were conducted

, which includes the BH Parcel (Ref. 34, pp. 8

, 9 ). Minnegasco, Inc.

, purchased the BH parcel in 1976 and sold the northern portion to the People’s Natural Gas Company (subseq uently known as UtiliCorp United and Aquila) (Refs. 6, p. 3; 34, p p

. 8, 9)

. Black Hills purchased certain assets of Aquila, including the BH Parcel, in 2008 (Ref. 34, p. 9).

Some of the waste resulting from the production of the manufactured gas, inclu ding coal tar

, was sold. Some wastes were disposed of at the facility (Ref. 39, p. 7). Coal tar is primarily composed of polycyclic aromatic hydrocarbons (PAHs) , phenolic compounds, light aromatic compounds, various inorganics and various sulfides (Ref s

. 8, p. 9; 3 9, pp. 6, 7). In December 1990, Ecology and Environment, Inc. (E&E)

, conducted a p reliminary a ssessment (PA) at INL&P to assess potential sources of contamination. The PA provided site

- related background information, estimates of possible wast e quantities produced, and a summary of nearby targets. No samples were collected as part of the PA (Ref. 6 , pp. 1 to 4 ). The PA postulated that PAH and cyanide waste may have been disposed of to the ground (Ref. 6, p. 8). Specific waste disposal practi ces at the former facility are unknown (Ref. 8, p. 9). Sampling of soil near former facility operating units and ground water in the vicinity of the property has documented the release of hazardous substances to the environment as described below and thro ughout this HRS documentation record.

In June 1992, HDR Engineering Inc. (HDR) of Omaha, Nebraska

, conducted a s ite i nvestigation (SI) of INL&P for Minnegasco, Inc. Eighteen soil samples were collected from six soil borings, and four ground water samples were collected from three monitoring wells installed during field operations. The six borings referred to as NOR

- 101 through NOR

- 106, were located near former facility features to investigate the possibility that releases of associated wastes to soil ha d occurred in the past (Ref. 7, pp. 7, 8). Both ground water and subsurface soil samples were found to contain PAH, aromatic volatile organics, and metals (Ref. 7 , pp. 9, 10, 23, 30, 47, 88, 134 and Appendix H [Laboratory Reports] ). M aximum concentration s of some PAHs detected in soil samples include naphthalene up to 1,400 milligrams per kilogram ( mg/kg ) , 2

- methylnaphthalene up to 860 mg/kg, acenaphthene up to 340 mg/kg, phenanthrene up to 520 mg/kg, and pyrene up to 200 mg/kg . M aximum concentrations of volatile organic compounds (VOC) detected in soil samples include acetone up to 2.50 mg/kg

, benzene up to 18 mg/kg

, ethylbenzene up to 70 mg/kg

, toluene up to 16 mg/kg

, and xylene (total) up to 47 mg/kg (Ref. 7, p. 23 and Appendix H ). M aximum concentrati on s of PAHs detected in ground water samples include

### 11 acenaphthene up to 0.550 milligrams per liter ( mg / L ) ; fluoranthene up to 0.210 mg/L; fluorene up to 0.310 mg/ L ; 2

- methylnap h thalene up to 2.70 mg/L; naphthalene up to 9.20 mg/L; phenanthrene up to 0.900 mg/L; and pyrene up to 0.320 mg/L . Maximum concentrations of VOCs detected in ground water samples include benzene up to 3.20 mg/L

, ethylbenzene up to 2.20 mg/L

, toluene up to 1.90 mg/L

, and xylene up to 2.40 mg/L ( Ref. 7, p. 30 and Appendix H ).

In Mar ch 2001, Tetra Tech EM Inc. prepared an e xpanded s ite i nspection (ESI) report for INL&P based on field activities performed by E&E in March 2000 (Refs. 5; 15 , p. 1 ). During the ESI field work, 62 soil, 20 direct push technology ground water, five municipa l well, four private well, and one on

- facility monitoring well samples were collected and analyzed using the Superfund Technical Assistance and Response Team (START) mobile laboratory. Further, 32 soil samples, 15 direct push ground water samples, all the potable municipal and private well samples, and the on

- facility monitoring well samples were submitted to the U.S. Environmental Protection Agency (EPA) Region 7 laboratory for confirmation analys i s (Ref. 5, p. 13). Results from the EPA Region 7 laborat ory analysis of on

- facility subsurface soil samples documented the following PAH s at the indicated maximum concentrations: acenaphthene (240 mg/kg) ; anthracene (33 mg/kg) ; benzo(a)anthracene (2.8 mg/kg) ; benzo(a)pyrene (2.3 mg/kg) ; benzo(b)fluoranthene ( 3.0 mg/kg) ; benzo(g,h,i)perylene (0.94 mg/kg) ; benzo(k)fluoranthene (2.5 mg/kg) ; chrysene (2.9 mg/kg) ; fluoranthene (140 J mg/kg ) ; fluorene (130 mg/kg) ; indeno(1,2,3

- cd)pyrene (1.2 mg/kg) ; 2

- methylnaphthalene (410 mg/kg) ; naphthalene (600 mg/kg) ; phenanth rene (500 mg/kg) ; and pyrene (220 mg/kg) (Ref. 5, pp. 171, 180, 181, 183, 184). In addition, the following aromatic VOCs and their maximum concentrations were reported in on

- facility soil samples: benzene (39 mg/kg), ethylbenzene (91 mg/kg), toluene (14 m g/kg), and total xylenes (130 mg/kg) (Ref. 5, pp. 165, 178, 179, 182). The majority of these contaminants were also detected in on

- facility ground water samples. One sample from an on

- facility fixed monitoring well containe d 11,455 micrograms per liter ( μ g/L) total PAH and 710 μ g/L total aromatic hydrocarbons

, including 250 μg/L of benzene (Ref. 5, pp. 35, 36, 158

- 160).

During the ESI, 10 ground water wells were sampled and analyzed for low detection limit VOC s, metals, cyanide, and semivolatile orga nic compound s (SVOC) . Specifically, five downgradient municipal wells (municipal wells 1 through 5) located approximately 0.25 mile from the INL&P , and an upgradient municipal well (municipal well 10), two shallow private domestic wells, a food processing well, and the Norfolk Rescue Mission well were sampled. Benzene was found in all five nearby municipal wells at concentrations ranging from 0.14 to 3.8 μg/L (Ref s . 5, p p . 36 , 130, 149, 155 ; 15, pp. 6, 9, 10 ). Two of the municipal wells have been closed because of the benzene contamination (Ref. 5, pp. 11, 12, 31) . The C ity of Norfolk operates a total of 11 municipal wells that serve the entire population (Ref. 5, p

. 31). Based on further investigations

, the likely source of the benzene contamination fo und in the municipal wells is a leaking underground storage tank site that is currently undergoing remediation through a state program (Ref. 34, p p . 12, 13, 74, 98

– 100 , 111

– 112 ).

In April of 2007, Aquila, Inc. and Centel Corporation entered into an Administrative Settlement Agreement and Order on Consent for Engineering Evaluation/Cost Analysis (EE/CA) with the U.S. Environmental Protection Agency (Ref. 39, p. 1)

.

An EE/CA field investigation was conducted in November and December 2007, June and Ju ly 2009, and January 2010. The field investigation included advancing soil, electrical conductivity (EC), laser

- induced fluorescence (LIF), and ground water probes; advancing soil borings; installing and developing monitoring wells; measuring ground water elevations; collecting samples of environmental media; and surveying. Sampling included collecting subsurface soil and ground water samples from direct

- push probes and ground water samples from newly installed monitoring wells. A subsurface soil sample was also collected and submitted for geotechnical analysis. These field activities were designed to gather data to better define and characterize the subsurface geology and site hydrogeology and the approximate extent

### 12 of soil, dense nonaqueous phase liqui d (DNAPL), and dissolved

- phase ground water contamination at INL&P (Ref. 34, p. 14).

Eleven soil probes (SP

- 01 through SP

- 11) were advanced and subsurface soil samples collected for chemical analysis to supplement the existing EPA analytical data suitab le for use in a baseline risk assessment. The samples were collected to define the approximate extent of soil contamination in the unsaturated zone (Ref. 34, p p . 15 , 76 ). Fourteen ground water probes were advanced at INL&P

, and three samples were collect ed from each probe (Ref. 34, p p

. 17 , 75 ). Monitoring wells were installed in soil borings . Two nested monitoring wells were installed at each location to monitor the upper and lower portions of the surficial aquifer (Ref. 34, p p . 18 , 56, 75, 341

- 354 )

. The soil and ground water samples confirm the release of VOC s and PAHs from former MGP operations to soil and ground water (Ref. 34,
pp. 46, 47, 59, 60 , and Appendices J [pp. 440

- 453] and K [pp. 454

- 541] ).

Between November 2013 and June 2014 removal ac tivities occurred at the site as required by the Administrative Settlement Agreement and Order on Consent for Removal Action established with the EPA. Contaminated soil and highly concentrated residuals (source material) were excavated, consolidated, and transported off the property for disposal at the Butler County Landfill. (Ref. 46, p. 4) Soil was excavated to depths ranging from 2.5 to 17 feet below ground surface across the majority of the property . The entire Northern portion of the property and th e western 2/3 of the southern portion of the property were excavated to the ground water table, approximately 16 to 17 feet below ground surface (Ref. 46, p p

. 4, 29). Approximately 10,425 tons of contaminated soil/small debris were excavated and transport ed to the Butler County Landfill (Ref. 46, p. 4) . The extent of soil removed is presented on Figure s 3

- 1 and 3

- 2 of the soil removal summary report (Ref, 46, p p

. 37, 38). Following soil removal, confirmation soil samples were collected from the base and w alls of the excavation to evaluate residual soil contamination (Ref. 46, pp. 4, 37, 38). In the final wall confirmation samples, benzo(a) anthracene, benzo(a)pyrene, benzo(b)fluoranthene and indeno(1,2,3

- cd)pyrene remained at concentrations exceeding clea nup levels in two or more samples (Ref. 46, p. 28). In the base samples, nine collected from 2 to 10 feet bgs exceeded the benzo(a) p yrene cleanup level (Ref. 46 , p. 31 )

. The residents in the area surrounding INL&P, including the City of Norfolk, obtain drinking water supplies from ground water drawn from the alluvium and Niobrara chalk aquifer underlying INL&P and the surrounding area (Refs. 3; 10, pp. 1

- 11 , 34, 35; 11, pp. 3, 9; 17; 27; 41; 43). As documented in Table 2 6 of this HRS documentation rec ord, more than 35, 900 persons obtain drinking water from the alluvium and Niobrara chalk aquifer. A l s o as documented in Table 2 6 of this HRS documentation record, one of the City of Norfolk’s supply wells is located within the 0.25 to 0.50 target distance categories of INL&P. This well is one of the 11 wells that supplies drinking water to more than 34, 397 residents

, students and workers

, as documented in Section 3.3.2.4 of this HRS documentation record.

### Source No: 1

13 Source Characterization 2.2 SOURCE CHARACTERIZATION

2.2.1 SOURCE IDE NTIFICATION

Name of source: Contaminated Soil associated with Facility Operations

Number of source: 1

Source Type : Contaminated Soil

Description and Location of Source (with reference to a map of the site):

Source 1 consists of contaminated soil asso ciated with the past production of manufactured gas. The facility produced coal gas from 1902 until 1948 using a water

- gas process (Ref. 39, p. 6). Generators produced a combustible gas using coke, steam, and oil products (Ref. 39, p. 6). As the gas cool ed through the production process, coal tar would fall from suspension in the gas and become a waste product (Ref. 39, p. 6). A scrubber was used to condense the gas (Ref. 39, p. 6). Coal tar was ultimately separated from the condensate water (Ref. 39, p . 6). Purifier boxes were used to remove sulfides and cyanides from the cool gas. Iron oxides were mixed with fluffing material (primarily wood chips, sawdust and corncobs) in the purifier boxes to provide for additional removal of water vapor and coal t ar with the associated hydrogen sulfide and cyanide (Ref. 39, p. 6). After the gas was manufactured, it was stored in
gas holders. Coal tar residuals were also present in the gas holders (Ref. 39, p. 6)

. Some of the waste resulting from the production of the manufactured gas, including coal tar, was sold. Some wastes were disposed of at the facility (Ref. 39, p. 7). Coal tar is primarily composed of polycyclic aromatic hydrocarbons, phenolic compounds, light aromatic compounds, various inorganics and various sulfides (Ref. 39, pp. 6, 7). In December 1990, Ecology and Environment, Inc. (E&E), completed a preliminary assessment (PA) at INL&P to assess potential sources of contamination. The PA provided site

- related background information, estimates of possible waste quantities produced, and a summary of nearby targets. No samples were collected as part of the PA (Ref. 6, pp. 1 to 4). The PA postulated that PAH and cyanide waste may have been disposed of to the ground (Ref. 6, p. 8). In June 1992, HDR Engineering Inc. (HDR) of Omaha, Nebraska, conducted a site investigation (SI) of INL&P for Minnegasco, Inc. (Ref. 7, pp. 1, 47, 88, 134)

. Eighteen soil samples were collected from six soil borings, and four ground water samples were collected from three monitoring wells installed during field operations (Ref. 7, pp. 7, 8, 47, 88, 134 ) . The six borings referred to as NOR

- 101 through NOR

- 106, were located near former facility features to investigate the possibility that releases of associated wastes
to so il had occurred in the past (Ref. 7, pp. 7, 8). PAHs were det ected in soil samples from borings NOR

101, NOR

- 102, NOR

- 103, NOR

- 104, NOR

- 105 and NOR

- 106 consistent with coal tar. (Ref. 7, p. 23 )

Two sampling events have occurred at INL&P that are used to characterize this source. A nalytical results for s oil sample s from the 2000 ESI and the 2007 soil sampling conducted as part of an EE/CA were used
to identify residual contamination in soil from processes associated with the production of manufactured
gas (Refs. 13, pp. 17

- 19, 24 ; 34, pp. 6, 14, 15 , 16 ). During the ESI , soil samples were collected at or near the following former MGP features: gas purifiers, condenser, scrubber, generator, and various 10,000

- cubic

- foot gas holders as well as additional locations to the south to define the approximate extent of contamination (Ref s . 5, p. 17 ; 7, pp . 7, 8 ). The text below provides additional information on the history of the property and various investigations. It also introduces the results of the soil s ampling. Soil sample locations are presented on Figure 2.

### Source No: 1

14 Source Characterization During the ESI, 32 soil samples were submitted to the EPA Region 7 laboratory for analys i s . Results from the EPA Region 7 laboratory analysis of subsurface soil samples documented the following PAH s at the indicated maximum concentrations: acenaphthene (240 milligrams per kilogram [ mg/kg ] ) ; anthracene (33 mg/kg) ; benzo(a)anthracene (2.8 mg/kg) ; benzo(a)pyrene (2.3 mg/kg) ; benzo(b)fluoranthene (3.0 mg/kg) ; benzo(g,h,i)perylene (0.94 mg/kg) ; ben zo(k)fluoranthene (2.5 mg/kg) ; chrysene (2.9 mg/kg) ; fluoranthene (140 J mg/kg ) ; fluorene (130 mg/kg) ; indeno(1,2,3

- cd)pyrene (1.2 mg/kg ); 2

- methylnaphthalene (410 mg/kg) ; naphthalene (600 mg/kg) ; phenanthrene (500 mg/kg) ; and pyrene (220 mg/kg) (Ref. 5, pp. 171, 180, 181, 183, 184). In addition, the following aromatic VOC s, and their maximum concentrations

, were reported in soil samples: benzene (39 mg/kg), ethylbenzene (91 mg/kg), toluene (14 mg/kg), and total xylenes (130 mg/kg) (Ref. 5, pp. 165, 178, 179, 182).

Between November 2013 and June 2014 removal activities occurred as required by the Administrative Settlement Agreement and Order on Consent for Removal Action established with the EPA. Contaminated soil and highly concentrated residuals (sour ce material) were excavated, consolidated, and transported off the property for disposal (Ref. 46, p. 4)

. Soil was excavated to depths ranging from 2.5 to 17 feet below ground surface across the majority of the property (Ref. 46, p. 4, 29) . Approximately 10,425 tons of contaminated soil/small debris were excavated and transported to the Butler County Landfill. The extent of soil removed is presented on Figure s 3

- 1 and 3

- 2 of the soil removal summary report (Ref, 46, p p

. 37, 38). Following soil removal, c onfirmation soil samples were collected from the base and walls of the excavation to evaluate residual soil contamination (Ref. 46, pp. 4, 37, 38). In the final wall confirmation samples, benzo(a) anthracene, benzo(a)pyrene, benzo(b)fluoranthene and inden o(1,2,3

- cd)pyrene remained at concentrations exceeding cleanup levels in two or more samples (Ref. 46, p. 28) , documenting that contamination still remains in site soils. In addition, releases from the

source to shallow ground water were not addressed as p art of the removal activities

.

### Source No: 1

15 Source Characterization

### Source No: 1

16 Source Characterization 2.2.2 HAZARDOUS SUBSTANCES ASSOCIATED WITH THE SOURCE

The hazardous substances associated with the area of contaminated soil ( Source 1 ) at INL&P are identified using analytical data for soil from the 2000 ESI and the 2007 EE/CA. The analytical data used to characterize Source 1 are described separately in the sections below.

200 0 Expanded Site Inspection Soil Samples :

ESI field activities occurred between March 19 and 25, 200 0

, and were completed in accordance wit h the site

- specific q uality a ssurance p roject p lan ( QAPP ) (Ref s . 5, p p

. 1, 13 ; 13 ). During the ESI field work, 62 soil samples were collected and analyzed using the mobile laboratory in accordance with the START Mobile Laboratory Program (MLP) QAPP (Ref. 5, pp. 13, 205

- 209) . Thirty

- two confirmatory soil samples were submitted to the EPA Region 7 laboratory for confirmation analysis (Ref. 5, pp. 13, 130, 131). Appendi ces B and C of Reference 5 provide cop ies of the field sheets, and analytical data for so il samples collected (Ref. 5, p p

. 85

- 118, 130 , 131, 163

- 165, 171

- 194 ). Samples collected by START were analyzed by the EPA Region 7 laboratory under analytical services request (ASR) number 539, activity number TJC13 (Ref. 5, pp. 128

- 131). The laborator y analyzed the samples in accordance with EPA Region 7 Standard Operating Procedure ( SOP ) 1640.1A, EPA Region 7 Laboratory QAPP (Ref. 13, p. 29). SVOC s were analyzed in accordance the EPA Region 7 SOP 3230.2B for extraction and analysis of water and solid s for SVOC s dated February 1995. The VOC s were analyzed in accordance with EPA Region 7 SOP 3230.1C, Gas Chromatography/Mass Spectrometry ( GC/MS ) Analysis for VOCs

, dated October 1993 . The metals were analyzed in accordance EPA Region 7 SOP 3122.2B, anal ysis for metals by TJA ICAP 61, April 1995 (Ref. 13, p. 31). The ASR for the sample analysis is provided on page 80 of Reference 13. The data were validated in accordance with procedures outlined in Section 6.5 of the QAPP (Refs. 13, p. 34; 5, p. 132)

. T he chain

- of custody form s for the samples collected during the ESI and sent to the EPA Region 7 laboratory are provided as Appendix B of Reference 5, pages 124 to 127. The logbook notes documenting sampling are provided as Appendix D of Reference 5 , pages 211

- 237

. A modified grid system was established in the southern portion of the INL&P property to identify possible soil contamination from MGP operations. Surface and subsurface soil samples were collected within the grid. S oil sampling locations o n the northern portion of the property were biased toward MGP features, such as gas holders (Ref. 5, pp. 13, 14).

T he lithology of each borehole and sample depth were noted d uring the soil sampling to characterize the soil and near

- surface lithology. The visual inspection

, organic vapor analyzer readings of the borehole material

, and initial field analytical data were used to select the depths of samples collection across the study area . Based on those data and observations, soil samples generally were c ollected within the intervals from 0 to 4 feet below ground surface (bgs), 7 to 11 feet bgs, and 13 to 16 feet bgs (Ref. 5, p. 14).

The locations of the soil samples on the property are shown in Figure 3

- 1, page 17, of Reference 5. Sampling locations o ff of the facility , including the background soil sampling locations, are shown in Figure 3

- 2, page 18, of Reference 5. Reference 15 summarizes the ESI field activities.

200 0 Expanded Site Inspection

- Background Concentrations:

During the ESI, seve n designated background samples were collected at various depths (from 0 to 2 inches to 13 to 14 feet bgs ) from a single direct push technology borehole location designated as GP

- 8. (Ref. 5, pp. 23, 131)

. All of these samples were analyzed by the EPA Regi on 7 laboratory (Ref. 5, p p . 14

- 16, 110

- 116 ). Th e location of the background sample is approximately three city blocks northwest and upgradient of the facility (Ref. 5, p. 18). The locations of the background and release samples are shown

### Source No: 1

17 Source Characterization in Figure 3

- 2, page 18, of Reference 5. The background and release samples were collected during the

same period of time using the same sampling procedures (Ref. 5, p. 13), were analyzed using the same analytical methods (Ref. 5, p p. 14, 13 0

- 132 ), and were collected fro m the same soil association (Refs. 5, p. 18; 11, pp. 9

- 11). In addition to the soil samples collected from GP

- 8, several other soil samples collected from the facility were analyzed and did not contain hazardous substances including SB

- 1, located north o f the former facility and SB

- 28 located west of the former facility and north of a transformer yard (Ref. 5, pp 15, 17).

As documented in Tables 1 and 3 below , the ESI background and release samples were collected from the

same relative depths. Field she ets were used to document sample locations

, collection times

, and dates

. Field sheets are referenced in Table 1 and 3

. Table 1 provides a summary of background soil samples and sampling dates. Table 2 summarizes the concentrations of hazardous substance s detected in the background soil samples.

TABLE 1 ESI BACKGROUND SOIL SAMPLES

Sample Identification (depth) Laboratory Sample Number Sample Medium Date Reference

GP

- 8 (0

- 2") 226 Soil 3/24/00 5, pp. 18, 59, 110, 126, 131, 229, 233

GP

- 8 (1

- 2') 227 Soi l 3/23/00 5, pp. 18, 59, 111, 126, 131, 229

GP

- 8 (3

- 4') 228 Soil 3/23/00 5, pp. 18, 59, 112, 126, 131, 229

GP

- 8 (4

- 7') 229 Soil 3/23/00 5, pp. 18, 59, 113, 126, 131, 229

GP

- 8 (8

- 10') 230 Soil 3/23/00 5, pp. 18, 59, 114, 126, 131, 229

GP

- 8 (11

- 13') 231 Soil 3/23/00 5, pp. 18, 59, 115, 126, 131, 229

GP

- 8 (13

- 14') 232 Soil 3/23/00 5, pp. 18, 59, 116, 126, 131, 229

SB

- 1 (11

- 13’) 211 Soil 3/21/00 5, pp. 17, 95, 124, 130

SB

- 28 (13

- 14’) 216 Soil 3/22/00 5, pp. 17, 100, 124, 130

Notes:

" Inches

' Feet GP Ge oprobe

### Source No: 1

18 Source Characterization TABLE 2 ESI BACKGROUND SOIL CONCENTRATIONS

Hazardous Substance Sample Identification (sample depth) Laboratory Sample Number Hazardous Substance Concentration (μg/kg) Sample Quantitation Limit (SQL)* (μg/kg) Reference 5 Reference 45 Acenaphthene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 186 p. 1 86 p. 189 p. 189 p. 189 p. 189 p. 192 p. 174 p. 180 p. 170 p. 173 p. 176 p. 179 p. 182 p. 185 p. 188 p. 126 p. 140 Anthracene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 22 8 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 186 p. 186 p. 189 p. 189 p. 189 p. 189 p. 192 p. 174 p. 180 p. 170 p. 173 p. 176 p. 179 p. 182 p. 185 p. 188 p. 126 p. 140 Benz o (a) anth racene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 1 86 p. 186 p. 189 p. 189 p. 189 p. 189 p. 192 p. 174 p. 180 p. 170 p. 173 p. 176 p. 179 p. 182 p. 185 p. 188 p. 126 p. 141 Benzo(a)
pyrene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’ ) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 186 p. 186 p. 189 p. 189 p. 189 p. 189 p. 192 p. 174 p. 180 p. 170 p. 173 p. 176 p. 179 p. 182 p. 185 p. 188 p. 126 p. 141 B enzo(b) fluoranthene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 52 0 440 450 p. 186 p. 186 p. 189 p. 189 p. 189 p. 189 p. 192 p. 174 p. 180 p. 170 p. 173 p. 176 p. 179 p. 182 p. 185 p. 188 p. 126 p. 141

### Source No: 1

19 Source Characterization TABLE 2 ESI BACKGROUND SOIL CONCENTRATIONS

Hazardous Substance Sample Identification (sample depth) Laboratory Sample Number Hazardous Substance Concentration (μg/kg) Sample Quantitation Limit (SQL)* (μg/kg) Reference 5 Reference 45 Benzo(g,h,i) perylene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (1 1

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 186 p. 186 p. 189 p. 189 p. 189 p. 189 p. 192 p. 174 p. 180 p. 170 p. 173 p. 176 p. 179 p. 182 p. 185
p. 188 p. 126 p. 141 Benzo(k) fluoranthene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 40 0 450 450 450 470 520 440 450 p. 186 p. 186 p. 189 p. 189 p. 189 p. 189 p. 192 p. 174 p. 180 p. 170 p. 173 p. 176 p. 179 p. 182 p. 185 p. 188 p. 126 p. 141 Chrysene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 170 p. 173 p. 176 p. 179 p. 182
p. 185 p. 188 p. 126 p. 141 Fluoranthene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 171 p. 174 p. 177 p. 180 p. 183 p. 186 p. 188 p. 126 p. 141 Fluorene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') S B

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 171 p. 174 p. 177 p. 180 p. 183 p. 1 85 p. 188 p. 126 p. 141

### Source No: 1

20 Source Characterization TABLE 2 ESI BACKGROUND SOIL CONCENTRATIONS

Hazardous Substance Sample Identification (sample depth) Laboratory Sample Number Hazardous Substance Concentration (μg/kg) Sample Quantitation Limit (SQL)* (μg/kg) Reference 5 Reference 45 Indeno(1,2,3

- cd)pyrene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 171 p. 174 p. 177 p. 180 p. 183 p. 186 p. 189 p. 127 p. 141 2

- Methyl

naphthalene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 1 3') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 171 p. 174 p. 17 7 p. 180 p. 183 p. 186 p. 189 p. 127 p. 141 Naphthalene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 44 0 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 171 p. 174 p. 177 p. 180 p. 183 p. 186 p. 189 p. 127 p. 141 Phenanthrene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 440 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 171 p. 174 p. 1 77 p. 180 p. 183 p. 186 p. 189 p. 127 p. 142 Pyrene GP

- 8 (0

- 2") GP

- 8 (1

- 2') GP

- 8 (3

- 4') GP

- 8 (4

- 7') GP

- 8 (8

- 10') GP

- 8 (11

- 13') GP

- 8 (13

- 14') SB

- 1 (11

- 13’) SB

- 28 (13

- 14’) 226 227 228 229 230 231 232 211 216 410 U 400 U 450 U 450 U 450 U 470 U 520 U 400 U 450 U 410 400 450 450 450 470 520 440 450 p. 187 p. 187 p. 190 p. 190 p. 190 p. 190 p. 193 p. 175 p. 181 p. 171 p. 174 p. 177 p. 180 p. 183 p. 186 p. 189 p. 127 p. 142

### Source No: 1

21 Source Characterization TABLE 2 ESI BACKGROUND SOIL CONCENTRATIONS

Hazardous Sample Sample Laboratory Substance Quantitation Hazardous Identification Sample Concentration Limit (SQL)* Substance (sample depth) Number (μg/kg) (μg/kg) Reference 5 Reference 45
Notes: * The SQL is the laboratory's contract required quantitation limit (CRQL), for a nalyses performed by CLP, or the laboratory's reporting limit (RL), for other laboratories, for that analyte with any di lution factor, volume adjustment, or percent solids for that sample analysis taken into account (Ref. 45, p. 1)

. " Inches ' Feet μg/kg M icrograms per kilogram or parts per billion GP Geoprobe U Not detected at or above the reporting limit shown (Ref. 5, p. 129)



### 2000 Expanded Site Inspection - Source Samples:

Soil samples collected from INL&P that contained concentrations of hazardous substances that are at concentrations significantly above background concentrations are presented in Table 3 below. These samples were identified as soil borings with the sample identification starting with “SB” and were collected using a direct push tech nology rig (Refs. 13, pp. 18, 19; 15, pp. 1, 3). The concentrations of hazardous substances detected in the source samples are summarized in Table 4.

TABLE 3 ESI SUMMARY OF SOURCE 1 SAMPLES

Sample Identification Laboratory Sample Number Sample Medium Date Reference

SB

- 18 (1

- 2') 221 Soil 03/22/00 5, pp. 17, 105, 124, 131

SB

- 19 (1

- 2') 223 Soil 03/22/00 5, pp. 17, 107, 125, 131

SB

- 22 (3

- 4') 218 Soil 03/21 /00 5, pp. 17, 102, 124, 130

SB

- 22 (16

- 18') 214 Soil 03/21/00 5, pp. 17, 98, 124, 130

SB

- 23 (3

- 4' ) 219 Soil 03/21/00 5, pp. 17, 103, 124, 131

SB

- 23 (7

- 11') 217 Soil 03/21/00 5, pp. 17, 101, 124, 130

SB

- 5 (4

- 7') 202 Soil 03/21/00 5, pp. 17, 86, 124, 130

SB

- 5 (11

- 13’) 203 Soil 03/21/00 5, pp. 17, 87

, 124, 13 0

SB

- 3 (8

- 10 ') 206 Soil 03/21/00 5, pp. 17 , 90, 124, 130

SB

- 3 (13

- 16') 205 Soil 03/21/00 5, pp. 17, 89, 124, 130

SB

- 25 (13

- 14') 213 Soil 03/22/00 5, pp. 17, 97, 124, 130

SB

- 2 (13

- 17') 212 Soil 03/21/00 5, pp. 17, 96, 124, 130

SB

- 6 (14

- 16') 209 Soil 03/22/00 5, pp. 17, 93, 124, 130

Notes: ' Fe et SB Soil boring

### Sourc e No: 1

22 Source Characterization TABLE 4 ESI SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample Identification (sample depth) Laboratory Sample Number Background Sample A (see Table 2) Background Conc. B (see Table 2) (μg/ kg ) Hazardous Substance

Conc. (μg/kg) Sa mple Quantitation Limit (SQL)* (μg/k g) Ref. 5 Ref. 45 Acenaphthene SB

- 22 (3

- 4') SB

- 22 (16

- 18') SB

- 23 (3

- 4') SB

- 23 (7

- 11') SB

- 5 (4

- 7') SB

- 3 (8

- 10) SB

- 3 (13

- 16') SB

- 2 (13

- 17') SB

- 6 (14

- 16') 218 214 219 217 202 206 205 212 209 GP

- 8 (3

- 4’) GP

- 8 (13

- 14’)

GP

- 8 ( 3

- 4’) GP

- 8 (8

- 10’) GP

- 8 (4

- 7’) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) 450 U 520 U 450 U 450 U 450 U 450 U 520 U 520 U 520 U 84,000 180,000 13,000 240,000

4,100 78,000 42,000 38,000 54,000 54,000 120,000

8,800 120,000

1,700 25,000 13,000 13, 000 26,000 p. 180 p. 177 p. 180 p. 180 p. 163 p. 171 p. 171 p. 177 p. 174 p. 146 p. 135 p. 149 p. 143 p. 101 p. 113 p. 110 p. 129 p. 120 Anthracene SB

- 23 (3

- 4') SB

- 5 (4

- 7') SB

- 3 (8

- 10) SB

- 3 (13

- 16') SB

- 2 (13

- 17') 219 202 206 205 212 GP

- 8 (3

- 4’) GP

- 8 (4

- 7’ ) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) 450 U 450 U 450 U 520 U 520 U 9,800 1,900 33,000 20,000 15,000 8,800 1,700 25,000 13,000 13,000 p. 180 p. 163 p. 171 p. 171 p. 177 p. 149 p. 101 p. 113 p. 110 p. 129 Benz o (a) anthracene SB

- 18 (1

- 2') SB

- 19 (1

- 2') 221 223 GP

- 8 (1

- 2’) GP

- 8 (1

- 2’) 400 U 400 U 2,800 790 1,700 510 p. 183 p. 183 p. 155 p. 161 Benzo(a) P yrene SB

- 18 (1

- 2') SB

- 19 (1

- 2') 221 223 GP

- 8 (1

- 2’) GP

- 8 (1

- 2’) 400 U 400 U 2,300 1,100 1,700 510 p. 183 p. 183 p. 155 p. 161 Benzo(b) fluoranthene SB

- 1 8 (1

- 2') SB

- 19 (1

- 2') 221 223 GP

- 8 (1

- 2’) GP

- 8 (1

- 2’) 400 U 400 U 3,000 2,400 1,700 510 p. 183 p. 183 p. 155 p. 161 Benzo(g,h,i) perylene SB

- 19 (1

- 2') 223 GP

- 8 (1

- 2’) 400 U 940 510 p. 183 p. 161

Benzo(k) fluoranthene SB

- 19 (1

- 2') 223 GP

- 8 (1

- 2’) 400 U 2, 500 510 p. 183 p. 161

Chrysene SB

- 18 (1

- 2') 221 GP

- 8 (1

- 2’) 400 U 2,900 1,700 p. 184 p. 156 Fluoranthene SB

- 18 (1

- 2') SB

- 23 (3

- 4') 221 219 GP

- 8 (1

- 2’) GP

- 8 (3

- 4’) 400 U 450 U 6,900 12,000 1,700 8,800 p. 184 p. 181 p. 156 p. 150 Fluorene SB

- 22 (3

- 4') SB

- 23 (3

- 4') SB

- 23 (7

- 11') SB

- 5 (4

- 7') SB

- 3 (8

- 10) SB

- 3 (13

- 16') SB

- 2 (13

- 17') 218 219 217 202 206 205 212 GP

- 8 (1

- 2’) GP

- 8 (3

- 4’) GP

- 8 (8

- 10’) GP

- 8 (4

- 7’) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) 400 U 450 U 450 U 450 U 450 U 520 U 520 U 57,000 10,000 130,0 00

1,900 29,000 18,000 13,000 54,000 8,800 120,000

1,700 25,000 13,000 13,000 p. 181 p. 181 p. 181 p. 164 p. 172 p. 172 p. 178 p. 147 p. 150 p. 144 p. 102 p. 114 p. 111 p. 129

2

- Methyl

naphthalene SB

- 19 (1

- 2') SB

- 22 (3

- 4') SB

- 22 (16

- 18') SB

- 23 (3

- 4') SB

- 23 (7

- 11') SB

- 25 (13

- 14') SB

- 5 (4

- 7') SB

- 3 (8

- 10) SB

- 3 (13

- 16') SB

- 2 (13

- 17') SB

- 6 (14

- 16') 223 218 214 219 217 213 202 206 205 212 209 GP

- 8 (1

- 2’) GP

- 8 (3

- 4’) GP

- 8 (13

- 14’)

GP

- 8 (3

- 4’) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’)

GP

- 8 (4

- 7’) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) 400 U 450 U 520 U 450 U 450 U 520 U 450 U 450 U 520 U 520 U 520 U 610 63,000 390,000 36,000 410,000 13,000 3,200 130,000 45,000 47,000 100,000 510 54,000 120,000

8,800 120,000

1,800 1,700 25,000 13,000 13,000 26,000 p. 184 p. 181
p. 178 p. 181 p. 181 p. 178 p. 164 p. 172 p. 172 p. 178 p. 175 p. 162 p. 147 p. 135 p. 150 p. 144 p. 133 p. 102 p. 114 p. 111 p. 130 p. 121 Indeno(1,2,3

- cd)pyrene SB

- 19 (1

- 2') 223 GP

- 8 (1

- 2’) 400 U 1,200 510 p. 184 p. 162

### Sourc e No: 1

TABLE 4 ESI SOURCE 1 SOIL CONCENTRATIONS

23 Source Characterization Hazardous Substance Sample Identification (sample depth) Laboratory Sample Number Background
A Sample (see Table 2) Background
B Conc. (see Table 2) (μg/ kg ) Hazardous Substance

Conc. (μg/kg) Sa mple Quantitation Limit (SQL)* (μg/k g) Ref. 5 Ref. 45 Naphthalene SB

- 22 (16

- 18') SB

- 23 (3

- 4') SB

- 23 (7

- 11') SB

- 25 (13

- 14') SB

- 5 (4

- 7') SB

- 3 (8

- 10) SB

- 3 (13

- 16') SB

- 2 (13

- 17') SB

- 6 (14

- 16') 214 219 217 213 202 206 205 212 209 GP

- 8 (13

- 14’) GP

- 8 (3

- 4’) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’)

GP

- 8 (4

- 7’) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’ ) 520 U 450 U 450 U 520 U 450 U 450 U 520 U 520 U 520 U 570,000 41,000 600,000

5,100 11,000 170,000 70,000 61,000 130,000 120,000 8,800 120,000

1,800 1,700 25,000 13,000 13,000 26,000 p. 178 p. 181 p. 181 p. 178 p. 164 p. 172 p. 172 p. 178 p. 175 p. 136
p. 150 p. 144 p. 133 p. 102 p. 114 p. 111 p. 130 p. 121 Phenanthrene SB

- 18 (1

- 2') SB

- 19 (1

- 2') SB

- 22 (3

- 4') SB

- 22 (16

- 18') SB

- 23 (3

- 4') SB

- 23 (7

- 11') SB

- 5 (4

- 7') SB

- 3 (8

- 10) SB

- 3 (13

- 16') SB

- 2 (13

- 17') SB

- 6 (14

- 16') 221 223 218 214 219 217 202 206 205 212 2 09 GP

- 8 (1

- 2’) GP

- 8 (1

- 2’) GP

- 8 (3

- 4’) GP

- 8 (13

- 14’)

GP

- 8 (3

- 4’) GP

- 8 (3

- 4’) GP

- 8 (4

- 7) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) 400 U 400 U 450 U 520 U 450 U 450 U 450 U 450 U 520 U 520 U 520 U 8,200 850 170,000 350,000 37,000 500,000

6,800 140,000 80,000 66,000 87,000 1,700 510 54,000 120,000

8,800 120,000

1,700 25,000 13,000 13,000 26,000 p. 184 p. 184 p. 181 p. 178 p. 181 p. 181 p. 164 p. 172 p. 172 p. 178 p. 175 p. 156 p. 162 p. 148 p. 136 p. 150 p. 145 p. 102 p. 114 p. 111 p. 130 p. 121 Pyrene SB

- 18 (1

- 2') SB

- 19 (1

- 2') SB

- 22 (16

- 18') SB

- 23 (7

- 11') SB

- 5 (4

- 7') SB

- 3 (8

- 10) SB

- 3 (13

- 16') SB

- 2 (13

- 17') SB

- 6 (14

- 16') 221 223 214 217 202 206 205 212 209 GP

- 8 (1

- 2’) GP

- 8 (1

- 2’) GP

- 8 (13

- 14’)

GP

- 8 (3

- 4’) GP

- 8 (4

- 7) GP

- 8 (8

- 10’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) GP

- 8 (13

- 14’) 400 U 400 U 520 U 450 U 450 U 450 U 520 U 520 U 520 U 6,000 1,100 140,000 220,000

2,400 57,000 31,000 29,000 31,000 1,700 510 120,000 120,000

1,700 25,000 13,000 13,000 26,000 p. 184 p. 184 p. 178 p. 181 p. 164 p. 172 p. 172 p. 178 p. 175 p. 156 p. 162 p. 136 p. 145 p. 102 p. 114 p. 111 p. 130 p. 121
Notes: * The SQL is the laboratory's contract required quantitation limit (CRQL), for analyses performed by CLP, or the laboratory's reporting limit (RL), for other laboratories, for t hat analyte with any dilution factor, volume adjustment, or percent solids for that sample analysis taken into account (Ref. 45, p. 1)

. A The background sample used for each source sample is the background sample collected at the same depth as the source sample. For source samples collected at the depths of 7 and 11 feet below ground surface, samples GP

- 8 (4

- 7’), GP

- 8 (8

- 10’), or GP

- 8 (11

- 13’) could be used to establish background levels. As shown in Table 2 of this HRS documentation record, samples SB

- 1 (11 -13’) or SB

- 28 (13

- 14’) could also be presented as they did not contain PAH compounds. The deepest background samples collected were at 13 to 14 feet bgs. Therefore, the background sample collected at 13 to 14 feet bgs was used as background for all s oil samples collected at depths greater than 13 feet. Note that background contaminant levels are presented to show the relative increase of facility

- related contaminants over background.
B The concentration i n parenthesis is the detection limit as documented in Table 2 of this HRS documentation record

. ' Feet μg/L Micrograms per kilogram or parts per billion Conc. Concentration U Not detected at or above the reporting limit shown (Ref. 5, p. 129) Ref. Reference


### Also as part of the ESI field work, soil s amples were analyzed in the field u sing the mobile laboratory (Ref. 5, p. 13). Soil samples were analyzed for PAH compounds including naphthalene, benzo(a)anthracene, benzo(b)fluoranthene / benzo(k)fluoranthene, and benzo(a)pyrene were analyzed using the solid phase microextraction (SPME) methodology (Ref. 5, p. 203).

### Sourc e No: 1

24 Source Characterization Engineering Evaluation/Cost Analysis December 2007 Soil Sampling :

The EE/CA s ite c haracterization r eport for INL&P documents the field activities performed during the EE/CA investigation c onducted between November 2007 and January 2010. The EE/CA was conducted by an environmental consultant for Centel Corporation and Black Hills Corporation in accordance with the EPA Administrative Settlement Agreement and Order on Consent Docked No. CERCL A

- 07

- 2006

- 0159 (Ref s . 34, p. 6; 39). The analytical data for soil samples from the EE/CA are used to characterize Source 1 , area of contaminated soil.

The EE/CA field activities were completed as specified in the w ork p lan, t echnical m emorandum 1, and f ield s ampling p lan (Ref s . 37; 38; 40). Deviations from the planned work are summarized in Table 2

- 1

, page 55 of Reference 34. The field investigation included advancing soil borings

, collecting soil samples, and surveying sampling locations. Sampling i ncluded collecting subsurface soil from direct

- push probes for chemical analysis. These field activities were designed to gather data to better define the approximate extent of soil contamination at INL&P (Ref. 34, p. 14).

During historical investigatio ns, extensive soil probing and sampling shallow unsaturated soil was completed. However, the investigations did not completely define the approximate vertical extent of soil contamination. Therefore, additional investigation of subsurface soils was conduc ted during the EE/CA

. In December 2007, 11 soil probes (SP

- 01 through SP

- 11) were advanced and subsurface soil samples collected for chemical analysis to supplement the existing EPA analytical data suitable for use in a baseline risk assessment (Ref. 34, pp. 14, 15) . The soil samples delineated the approximate extent of soil contamination in the unsaturated zone. The locations of the probes are shown on Figure 2

- 2

, page 76 of Reference 34

, and soil probe logs are in Appendix C at page 276 of Reference 34 (Ref. 34, pp. 14, 15). According to the logs, the soil samples were collected in November and December 2007 (Ref. 34, pp. 276 to 294).

Soil probes were advanced with a hydraulic direct

- push probing unit. All probes were sampled continuously and logge d by a geologist to allow for accurate determination of stratigraphy and to screen for contamination. Photoionization detector (PID) field screening results are included on the logs (Ref. 34, p p . 15 , 277

- 315 ).

Soil samples collected from probes SP

- 01 t hrough SP

- 09 were submitted for chemical analysis of PAHs by SW

- 846 Method 8270

- Selective Ion Monitoring ( SIM ) , VOCs by SW

- 846 Method 8260B, and arsenic by SW

- 846 Method 6010B. The samples were collected from the zone that was the most visibly contaminate d or that exhibited the highest PID reading in the 1 to 6 foot, 6 to 12 foot, and 12 to 18 foot bgs intervals. T he soil samples were collected from the midpoint of the interval i f visible contamination was not present or the soil exhibited no PID reading in the sample interval . A duplicate sample was collected from probe SP

- 1 from 8.5 to 10.0 feet bgs

, and a matrix spike/matrix spike duplicate (MS/MSD) sample w as collected from probe SP

- 3 from 8.0 to 8.6 feet bgs. No soil samples were collected from s o il probe s SP

- 10 and SP

- 11 for chemical analysis (Ref. 34, pp. 15, 16).

All results received from the analytical laboratory for samples collected during the EE/CA were reviewed

, evaluated , and validated. Data validation reports are included as Appendix O of the EE/CA report (Ref. 34 pp. 59 6

- 650 )

. Data were evaluated using EPA’s Functional Guidelines for Evaluating Organics/Inorganics Analyses (EPA 1999

, 1994) (Ref. 34, p. 27). Reference 38 provides the work plan followed for sample validation.

Visible contamination, odors, or PID readings identified during probing or well installation were recorded on the logs presented in Appendix D of Reference 34. Figure 2

- 2 on page 76 of Reference 34 shows the soil probe locations. Table 4

- 1 page 58 of Reference 34 summarizes the field observations recorded ( such

### Sourc e No: 1

25 Source Characterization as visible tar, tar odors, and VOCs detected by the PID) during soil probing. A summary of Table 4

- 1 is provided in Table 5 of this HRS documentation record. Indications of contamination were present in all soil probes except in probe P

- 10

, which was advanced along 5th Street, approximately two blocks east of INL&P (Ref. 34, p p . 28 , 58 ).

TABLE 5 OBSERVATONS OF CONTAMINATION IN SOIL PROBES ENGINEERING EVALUTION/COST EVALUTION

Sample Identification Odors PID Reading G reater than 1 ppm Observations Reference
SP

- 01 Tar odor entire depth. Range from 11.9 to 1,724 ppm from 0.5 to

19 feet bgs. Peak reading at 16 feet bgs. Tar coating on sampling sleeve/sample tar coated from 10 to 16 feet bgs . T a r saturate d from 15.2 to 15.8 feet bgs

. Sand tar coated from 18.7 to 20 feet bgs

. 34, p p

. 58, 277

SP

- 02 Faint tar odor from 0.5 to 5 feet

bgs . Tar odor from 5 to 12 feet bgs

. Range from 8.8 to 634 ppm from 0.5 to 17 feet bgs. Peak reading at 13 feet bgs. Tar coa ted from 13.6 to 16 feet bgs

. 34, p p

. 58, 278

SP

- 03 Strong tar odor from 10 to 20 feet bgs

. Range from 8.7 to 649 ppm from 4 to 17 feet bgs. Peak reading at 127 feet bgs. Tar coated from 16.6 to 20 feet bgs

. 34, p p

. 58, 279

SP

- 04 Tar odor from 5 to 10 f eet bgs

. Range from 12.1 to 295 ppm from 0.5 to 19 feet bgs. Peak reading at 19 feet bgs. Tar coated from 12.6 to 12.9 feet bgs

. Sampling sleeve had a tar smear from 18 to 20 feet bgs

. 34, p p

. 58, 280

SP

- 05 Strong tar odor from 5 to 21 feet bgs . Petro l eum odor from 35 to

46 feet bgs

. Range from 5.9 to 1,503 ppm from 0.5 to

54 feet bgs . Peak reading at 18 feet bgs. Visible tar from 7 to 10 feet bgs . Tar coated from 10 to 17.7 feet bgs in clay. Tar coated from 20 to 21 feet

bgs in sand. Tar staining b egins grading out at 27 feet bgs . Tar stained from 35 to 35.5 feet bgs

. 34, pp. 58, 281, 282

SP

- 06 Petroleum odor at 8 feet bgs

. Range from 1.1 to 175 ppm from 9 to 31 feet bgs . Peak reading at 18 feet bgs. Petroleum saturated 24.7 feet bgs

. Petroleum coated seam from 27 to 27.1 feet bgs and 27.7 to 27.8 feet bgs

. 34, pp. 58, 283, 284

SP

- 07 None recorded. Range from 40.2 to 271 ppm from 0.5 to 5 feet bgs . Peak reading at 5 feet bgs

. Tar saturated from 5 to 7 feet bgs

. 34, p p. 58, 286

### Sourc e No: 1

26 Source Characterization TABLE 5 (Conti nued) OBSERVATONS OF CONTAMINATION IN SOIL PROBES ENGINEERING EVALUTION/COST EVALUTION

Sample Identification Odors PID Reading greater than 1 ppm Observations Reference
SP

- 08 Tar odor from 18 to 19.2 feet bgs

. Strong tar od or at 25.6 feet bgs . Faint

ga s odor above

glacial till. Range from 1.1 to 92.6 ppm from 7 to 32 feet bgs . Peak reading at 25 feet bgs. Tar stained at 25.6 feet bgs and from 27 to 27.8 feet bgs

. 34, pp. 58, 287, 288

SP

- 09 None. None

. None. Probe refusal at 7 feet bgs

. 34, p p. 58, 289

SP

- 10 None. PID measurements less than 1 ppm throughout probe. No contamination evident 34, p p. 58, 290 , 291, 292 SP

- 11 Petroleum odor at 16.7 to 17.9 feet bgs

, p etroleum odor

from 20.3 to 21.3 feet bgs

. Range from 1.0 to 19 ppm from 18 to 21 feet bg s . Peak reading at 18 feet bgs. Black staining from 16.7 to 17.9 and 20.3 to 21.3 feet bgs

. 34, p p. 58, 293

Notes: bgs Below ground surface PID Photoionization detector
ppm P arts per million



### Engineering Evaluation/Cost Analysis

- Background and Release Concentrations:

The background concentrations for soil sample s from 2000 were used to supplement background concentrations for the soil samples collected in 2007 during the EE/CA soil investigation. These locations collected during the ESI documented a n absence of contamination at locations away from the

source. Documentation on the background soil samples from the ESI is provided in Tables 1 and 2 of this HRS documentation record. Additionally, Table 5

- 2

, page 66 of Reference 34 provides background

c oncentrations for PAH s from various publications. No off

- property soil samples were collected as part of the EE/CA, rather all samples were located on the facility (Ref. 34, p. 76). However, one location (SP

08) sampled during the EE/CA was located outsi de the historic structure footprint at the former MGP (Ref. 34, p. 76). This sample contained significantly lower concentrations of PAH compounds when
compare d to samples collected near or within areas where historic structures were located (Ref. 34, pp. 59, 76). The results for two samples collected from SP

- 08 are presented in Table 7 below.

### Sourc e No: 1

27 Source Characterization TABLE 6 EE/CA BACKGROUND SOIL SAMPLES

Sample Identification (feet below ground surface) Laboratory Sample Number Sample Medium Date Reference

SP

- 8 (5

- 6) 6032085 007 Soil 11/30/2007 34, p. 287, 621

SP

- 8 (7

- 8) 6032085008 Soil 11/30/2007 34, p. 287, 621



### TABLE 7 EE/CA BACKGROUND SOIL CONCENTRATIONS

Hazardous Substance Sample Identification (sample depth) Laboratory Sample Number Hazardous Substance Concentration ( mg /kg) Method Det e ction Limit (MDL) ( mg /kg) Reference 34 Acenaphthene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 ND ND 0.0013 0.00024 p. 449

Acenaphthylene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.0641 ND 0.0026 0.00048 p. 449

Anthracene SP

- 8 (5

- 6 ) SP

- 8 (7

- 8) 6032085007 6032085008 0.0723 0.0020 0.0032 0.00061 p. 449

Benz o (a)anthracene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.232 ND 0.0026 0.00048 p. 449

Benzo(a)pyrene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.134 ND 0.0038 0.00073 p. 449

Benzo(b)fluoranthene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.422 ND 0.0045 0.00085 p. 449

Benzo(g,h,i)perylene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.113 ND 0.0026 0.00048 p. 449

Chrysene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.202 N D 0.0019 0.00036 p p. 449 , 450

Fluoranthene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.321 ND 0.0045 0.00085 pp. 449, 450

Fluorene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 ND ND 0.0019 0.00036 pp. 449, 450

Indeno(1,2,3

- cd)pyrene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.112 ND 0.0038 0.00073 pp. 449, 450

Naphthalene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.214 ND 0.0019 0.00036 pp. 449, 450

Phenanthrene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.548 0.0100 0.0038 0.00073 pp. 449, 450

Pyrene SP

- 8 (5

- 6) SP

- 8 (7

- 8) 6032085007 6032085008 0.35 ND 0.0032 0.00061 pp. 449, 450

Notes:

* The SQL is the laboratory's method d etection limit (MDL) (Ref. 34 , p p

. 449, 450 )

.

" Inches

' Feet μg/kg Micrograms per kilogram or parts per billion GP Geopro be



### Twenty

- two subsurface soil samples were collected from the nine soil probes advanced on facility during the EE/CA field investigation. The sampling locations are shown in Reference 34, page 75. The complete analytical data are presented in Appendix J of Reference 34. Soil samples collected from

### Sourc e No: 1

28 Source Characterization INL&P with hazardous substances that are used in delineating the approximate extent of source 1 are summarized in Table 8

, and the locations are shown on Figure 2 of this HRS documentation record (Ref. 1, Sec tion 2.3). The concentrations of hazardous substances detected in the source samples are summarized in Table 9 of this HRS documentation record

. V isible contamination (waste) was observed in the soil samples (see Table 5 in this HRS documentation record) . The soil samples were collected from biased locations, w h ere former MGP structures were located and known to have contained hazardous substances (Ref. 34, Figure 2

- 2, p. 76). The hazardous substances detected in the source samples such as PAHs are not naturally occurring but are created from a variety of anthropogenic activities (Ref. 42).

TABLE 8 

### ENGINEERING EVALUTION/COST ANALYSIS SUMMARY OF SOURCE 1 SAMPLES

- 2007

Sample Identification (feet b elow ground surface ) * Laboratory Sample Number Sample Medium Date Reference

SP

- 1 (4

- 5) SP01S0104

- 05P 6032561010 Soil 12/06/2007 34, p. 277 , 637

SP

- 1 (8.5

- 10) SP01S0208.5

- 10P 6032561011 Soil 12/06/2007 34, p. 277, 637

SP

- 1 (15

- 16) SP01S0315

- 15P 6032561012 Soil 12/06/2007 34, p. 277, 637

SP

- 2 (4

- 5) SP02S010 4

- 05P 6032561014 Soil 12/06/2007 34, p. 278, 637

SP

- 2 (9

- 10) SP02S0209

- 10P 6032561015 Soil 12/06/2007 34, p. 278, 637

SP

- 3 (4.5

- 5.5) SP03S0104.5

- 05.5P 6032561017 Soil 12/06/2007 34, p. 279, 637

SP

- 3 (8

- 8.6) SP03S0208

- 08.6P 6032561018 Soil 12/06/2007 34, p. 279, 638

SP

- 3 (12

- 13) SP03S0312

- 13P 6032561019 Soil 12/06/2007 34, p. 279, 638

SP

- 4 (12.5

- 13 .4 ) SP04S0112.5

- 13.4P 6032561005 Soil 12/05/2007 34, p. 280, 637

SP

- 5 ( 2.5

- 3.5 ) SP05S0102.5

- 03.5P 6032561007 Soil 12/06/2007 34, p. 281, 637

SP

- 5 ( 8

- 9 ) SP05 S0208

- 09P 6032561008 Soil 12/06/2007 34, p. 281, 637

SP

- 5 ( 11

- 12 ) SP05S03 11

- 12P 6032561009 Soil 12/06/2007 34, p. 281, 637

SP

- 6 (3

- 4) SP06S0103

- 04P 6032085004 Soil 11/28/2007 34, p. 283, 621

SP

- 6 (9

- 10) SP06S0109

- 10P 6032085005 Soil 11/28/2007 34, p. 28 3, 621

SP

- 7 (5

- 6) SP07S0105

- 06P 6032561006 Soil 12/06/2007 34, p. 286, 637

### Sourc e No: 1

29 Source Characterization Sample Identification (feet b elow ground surface ) * Laboratory Sample Number Sample Medium Date Reference

SP

- 9 (3

- 4) SP09SO103

- 04P 6032085009 Soil 11/30/2007 34, p. 289, 622

Notes: * The SP

- X designation is used for displaying the sample on figures and in tables. The longer sample d esignation is how the sample is named on boring logs and in the data validation reports. SP Soil probe

### Sourc e No: 1

30 Source Characterization TABLE 9 ENGINEERING EVALUTION/COST ANALYSIS 2007 SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample Identification ( ft bgs) A Background Sample (ft bgs ) B Background Concentration ( MDL mg / kg ) C Hazardous Substance Concentration (mg/kg) Method Detection Limit (MDL) (mg/kg) Reference 34 Acenaphthene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (9

- 10) SP

- 2 (1 2

- 12.5) SP

- 3 (8

- 8.6) SP

- 3 (12

- 13) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.470) ND (0.450) ND (0.470) ND (0.450) ND (0. 00024 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) ND (0.0013) ND (0.450) 13 40.4 92.4 2.06 1.9 1.93 0.577 13.8 31.8 17.4 32.3 143 18.7 18.3 628 0.542 0.0246 0.0241 0.126 0.0024 0. 0024 0.0024 0. 0026 0. 122 0. 119 0.0266 0.025 0.121 0.125 0.0121

2.99 0. 0 011 p. 441 p. 441 p. 442 p. 443 p. 443 p. 444 p. 445 p. 445 p. 445 p. 4 46 p. 446 p. 447 p. 447 p. 448 p. 448 p. 450 Acenaphthylene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 3 (4.5

- 5.5) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (4

- 7) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.450) ND (0. 00048 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.0641 (0.0026) 6.34 8.46 19. 7 1.1 2.94 15.2 3.59 5.31 21 2.61 2.62 215 0.0492 0.0482 0.253 0.0049 0.244 0.237 0.0532 0.0501 0.241 0.25 0.0243

5.98 p. 441 p. 442 p. 442 p. 444 p. 445 p. 445 p. 446 p. 446 p. 447 p. 447 p. 448 p. 449

### Sourc e No: 1

31 Source Characterization TABLE 9 (Continued) ENGINEERING EVALUTION/COST ANA LYSIS 2007 SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample I dentification ( ft bgs ) A Background Sample ( ft bgs ) B Background Concentration ( MDL mg / kg ) C Hazardous Substance Concentration (mg/kg) Method Detection Limit (MDL) (mg/kg) Reference 34
Ant hracene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (9

- 10) SP

- 2 (12

- 12.5) SP

- 3 (8

- 8.6) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.470) ND (0.450) ND (0.450) 0.0020 (0.00061) ND (0.470) ND (0.450) ND (0.450 ) ND (0 .470) ND (0.450) 0.0723 (0.0032)

ND (0.450) 7.41 45.5 38.7 0.82 0.72 0.801 14.6 77.2 6.79 11.8 49.3 8.69 10.9 332 0.73 0.0615 0.612 0.316 0.006 0.0061 0.0061 0.305 0.297 0.0665 0.0626 0.301 0.312 0.0303

7.48 0.0028 p. 441 p. 441 p. 442 p. 443 p. 443 p. 444 p. 445 p. 445 p. 446 p. 446 p. 447 p. 447 p. 448 p. 449 p. 450 Benz o (a) anthracene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (9

- 10) SP

- 3 (4.5

- 5.5) SP

- 3 (8

- 8.6) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) S P

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (8

- 10) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.450) ND (0.450) ND (0.450) ND (0. 00048 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.232 (0.0026)

ND (0.450) 4.87 12.7 18.7 0.62 0.728 0.601 4.62 43.5

5 6.39 29.5 2.6 8.2 206 1.72 0.0492 0. 0482 0.253 0.0048 0. 0049 0.0049 0.244 0.237 0.0532 0.0501 0.24 1 0.25 0.0243

5 .98 0.0022 p. 441 p. 442 p. 442 p. 443 p. 444 p. 444 p. 445 p. 445 p. 446 p. 446 p. 447 p. 447 p. 448 p. 449 p. 450

### Sourc e No: 1

32 Source Characterization TABLE 9 (Continued) ENGINEERING EVALUTION/COST ANALYSIS 2007 SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample Ide ntification ( ft bgs ) A Background Sample ( ft bgs ) B Background Concentration ( MLD mg / kg ) C Hazardous Substance Concentration (mg/kg) Method Detection Limit (MDL) (mg/kg) Reference 34 Benzo(a)
pyrene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 3 (4.5

- 5.5) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (4

- 7) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.450) ND (0. 00073 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.134 (0.0038)

ND (0.450) 2.21 5.33 9.39 0.918

2.6 26.6 2.93 3.42 15.7 2.55 6.18 114

1 0.0738 0.0724 0.379 0.0073 0.366 0.356 0.0798 0.0751 0.362 0.375 0.0364

8

. 89 0.0033 p. 441 p. 442 p. 442 p. 444 p. 445 p. 446 p. 446 p. 446 p. 447 p. 447 p. 448 p. 449 p. 450 Benzo(b) fluoranthene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 3 (4.5

- 5.5) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (4

- 7) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.450) ND (0. 00085 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.422 (0.0045)

ND (0.450) 2.86 7.16 12.2 1.72 4.51 38.2 4.2 5.11 21.7 2.75 9.47 174 2.25 0.0862 0.0844 0.443 0.0085 0.427 0.416 0.0931 0.0876 0.422 0.437 0.0425

10.5 0.0039 p. 441 p. 442 p. 442 p. 444 p. 445
p. 446 p. 446 p. 446 p. 447 p. 447 p. 448 p. 449 p. 450

### Sourc e No: 1

33 Source Characterization TABLE 9 (Continued) ENGINEERING EVALUTION/COST ANALYSIS 2007 SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample Identification ( ft bgs ) A Background Sample ( ft bgs ) B Background Concentration ( MDL mg / kg ) C Hazardous Substance Concentration (mg/kg) Method Detection Limit (MDL) (mg/kg) Reference 34 Benzo(g,h,i) perylene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 3 (4.5

- 5.5) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12 .5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (3

- 4) SP

- 6 (9

- 10) SP

- 7 (5

- 6) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (4

- 7) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) SP

- 08 (5

- 6) ND (0.450) ND (0.450 ) ND (0.520) ND (0.450) ND (0.450) ND (0. 00048 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) ND (0.450) 0.113 (0.0026) 1.22 1.87 4.68 0.708 2.14 12.1 1.32 1.51 6.17 0.946 0.0025

3.24 79.2 0.0492 0.0482 0.253 0.0049 0.244 0.237 0.0532 0.0501 0.241 0.25 0.02 1 0.0243

5.98 p. 441 p. 442 p. 442 p. 444 p. 445 p. 446 p. 446 p. 446 p. 447 p. 447 p. 448
p . 448 p. 449 Chrysene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 3 (4.5

- 5.5) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12 ) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (4

- 7) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.450) ND (0. 00036 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.202 (0.0019 )

ND (0.450) 3.82 9.70 16.3 0.914 3.94 31.8 3.96 5.1 22.9 2.83 6.68 160 1.29 0.0369 0.0362

0.19 0.0036 0.183 0.178 0.0399 0.0376 0.181 0.187 0.0182

4.49 0.0017 p. 441 p. 442 p. 442 p. 44 4 p. 445 p. 446 p. 446 p. 446 p. 447 p. 447 p. 448 p. 449 p. 450

### Sourc e No: 1

34 Source Characterization TABLE 9 (Continued) ENGINEERING EVALUTION/COST ANALYSIS 2007 SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample Identification ( ft bgs ) A Background Sample ( ft bgs ) B Background Conce ntration ( MDL mg / kg ) C Hazardous Substance Concentration (mg/kg) Method Detection Limit (MDL) (mg/kg) Reference 34
Fluoranthene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (4

- 5) SP

- 2 (12

- 12.5) SP

- 3 (4.5

- 5.5) SP

- 3 (8

- 8.6) SP

- 3 (12

- 13) SP

- 4 (7

- 8) SP

- 4 (12.5

- 1 3 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (4

- 7) GP

- 8 (11

- 13) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (11

- 13) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (3

- 4) SP

- 08 (5

- 6) ND (0.450 ) ND (0.450) ND (0.520) ND (0.450) ND (0.470) ND (0.450) ND (0.450) ND (0.470) ND (0. 00085 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.321 (0.0045) 7.25 17.4 31.5 0.0234 0.477 0.667 0.997 0.335

87 8.44 10.7 46.8 5.36 16.5 298 0.0862 0.0844 0. 443 0.00069 0.0086 0.0085 0.0085 0.0092 0.416 0.0931 0.0876 0.422 0.437 0.0425

10.5 p. 441 p. 442 p. 442
p. 443 p. 443 p. 444 p. 444 p. 445 p. 446 p. 446
p. 447 p. 447 p. 447 p. 448 p. 449 Fluorene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (9

- 10) SP

- 2 ( 12

- 12.5) SP

- 3 (8

- 8.6) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.470) ND (0.450) ND (0.450) ND (0. 00036 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) ND (0. 0019 ) 12.1 30.6 55.9 1.45 1.05 1.52 12.7 69.9 9.90 16.3 70 11.1 13. 2 484 0.0369 0.0362

0.19 0.0036 0.0037 0.0037 0.183 0.178 0.0399 0.0376 0.181 0.187 0.0182

4.49 p. 441 p. 442 p. 442 p. 443 p. 443 p. 444 p. 445 p. 446 p. 446 p. 447 p. 447 p. 447 p. 448 p. 449

### Sourc e No: 1

35 Source Characterization TABLE 9 (Continued) ENGINEERING EVALUTION/COST ANALYSIS 200 7 SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample Identification ( ft bgs ) A Background Sample ( ft bgs ) B Background Concentration ( MDL mg / kg ) C Hazardous Substance Concentration (mg/kg) Method Detection Limit (MDL) (mg/kg) Reference 34 Indeno(1,2,3

- c d) p yrene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 3 (4.5

- 5.5) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 6 (9

- 10) SP

- 7 (5

- 6) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (4

- 7) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (8

- 10) SP

- 08 (5

- 6) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.450) ND (0. 00073 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.450) 0.112 (0.0038) 0.795 1.82 3.26 0.603 1.36 10.6 1.1 1.29 6.11 2.8 47.8 0.0738 0.0724 0.379 0.0073 0.366 0.356 0.0798 0.0751 0.362 0.0364

8.98 p. 441 p. 442 p. 442 p. 444 p. 445 p. 446 p. 446 p. 447 p. 447 p. 448 p. 449 Naphthalene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (9

- 10) SP

- 2 (12

- 12.5) SP

- 3 (4.5

- 5.5) SP

- 3 (8

- 8.6) SP

- 3 (12

- 13) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.470) ND (0.450) ND (0.450) ND (0.470) ND (0.450) ND (0. 00036 )

ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.214 (0.0019)

ND (0.450) 24.6 77.1 373 6.87 9.02 0.932 7.28 3 .42 45.7 493 55.2 89.9 385 79.4 11.8 1

, 950 2.63 0.0369 0. 0 362

0.19 0.0036 0.0037 0.0036 0.0037 0.0039 0.183 0.178 0.0399 0.0376 0.181 0.187 0.0182

4.49 0.0017 p. 441 p. 442 p. 442 p. 443 p. 444 p. 444 p. 444 p. 445 p. 445 p. 446 p. 446 p. 447 p. 447 p. 447 p. 448 p. 449 p. 450

### Sourc e No: 1

36 Source Characterization TABLE 9 (Continued) ENGINEERING EVALUTION/COST ANALYSIS 2007 SOURCE 1 SOIL CONCENTRATIONS

Hazardous Substance Sample Identification ( ft bgs ) A Background Sample ( ft bgs) B Background Concentration ( MDL mg / kg ) C Hazardous Substance C oncentration (mg/kg) Method Detection Limit (MDL) (mg/kg) Reference 34
Phenanthrene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (9

- 10) SP

- 2 (12

- 12.5) SP

- 3 (4.5

- 5.5) SP

- 3 (8

- 8.6) SP

- 3 (12

- 13) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9 ) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.470) ND (0.450) ND (0.450) ND (0.470) ND (0.450) 0.0100 (0.00073) ND (0.470) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.548 (0.0038)

ND (0.450) 31.4 81.7 177 3.88 3.12 0.767 3.71 1.47 43.5 331 34.9 53.5 221 24.9 42.7 1

, 230 4.09 0.0738 0.0724 0.379 0.0072 0.0073 0.0073 0.0073 0.0079 0.366 0.356 0.0798 0.0751 0.362 0.375 0.0364

8.98 0.0033 p. 441 p. 442 p. 442 p. 443 p. 444 p. 444 p. 444 p. 445 p. 445 p. 446 p. 446 p. 447 p. 447 p. 447 p. 448 p. 449 p. 450 Py rene SP

- 1 (4

- 5) SP

- 1 (8.5

- 10) SP

- 1 (15

- 16) SP

- 2 (9

- 10) SP

- 2 (12

- 12.5) SP

- 3 (4.5

- 5.5) SP

- 3 (8

- 8.6) SP

- 4 (2

- 2.5) SP

- 4 (7

- 8) SP

- 4 (12.5

- 13 .4 ) SP

- 5 (2.5

- 3.5) SP

- 5 (8

- 9) SP

- 5 (11

- 12) SP

- 6 (9

- 10) SP

- 7 (5

- 6) SP

- 9 (3

- 4) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (13

- 14) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (4

- 7) GP

- 8 (8

- 10) GP

- 8 (3

- 4) SP

- 08 (7

- 8) GP

- 8 (11

- 13) GP

- 8 (3

- 4) GP

- 8 (8

- 10) GP

- 8 (11

- 13) GP

- 8 (8

- 10) SP

- 08 (5

- 6) GP

- 8 (3

- 4) ND (0.450) ND (0.450) ND (0.520) ND (0.450) ND (0.470) ND (0.450) ND (0.450) ND (0.450) ND (0. 00061 )

ND (0.47 0) ND (0.450) ND (0.450 ) ND (0.470) ND (0.450) 0.35 (0.0032) ND (0.450) 10.7 34 44.3 1.55 0.775 1.94 1.4 15.7 105 10.8 15.1 67.3 8.34 20.4 449 2.37 0.0615 0.0603 0.316 0.006 0.0061 0.0061 0.0061 0.305 0.297 0.0665 0.0626 0.301 0.312 0.0303

7.48 0.0028 p. 4 41 p. 442 p. 442 p. 443 p. 444 p. 444 p. 444 p. 445 p. 446 p. 446 p. 447 p. 447 p. 447 p. 448 p. 449 p. 450
Notes:
A The sample identifications are different on the figures, in the text of the report, and on the sample data sheets. The figures and text p rovide only the soil probe sample location, such as SB

- 1 (Ref. 34, pp. 58, 76) . The soil probe sample identification on the sample data sheets is given as the sample location, such as SP01, followed by a sample number, such as SP01 01 , followed by the samp le depth, such as SP0101 04

- 05

. The sample identification in the above table provide s the soil probe location, such as SB

- 1 for example , followed by the sample depth in feet in parenthesis, for example SB

- 1 (4

- 5).
B Background sample documentation for ESI samples collected in 2000 is provided in Table 1.
C Background sample concentration documentation for ESI samples collected in 2000 is provided in Table 2. The values in Table 2 were presented in micrograms per kilogram (μg/kg) and are displayed in this t able as milligrams per kilogram (mg/kg) for consistency. To convert micrograms to milligrams, one must divide micrograms by 1,000 .

m g/kg Milli grams per kilogram bgs Below ground surface ft Feet MDL Method detection limit ND Not d etected SP Sampling point GP Geoprobe point

### Sourc e No: 1

37 Source Characterization 2.2.3 HAZARDOUS SUBSTANCES AVAILABLE TO A PATHWAY

Containment values are based on an observed release from source area to ground water and the absence of any documented containment features. Much of the subsurface soil contamination is covered by buildings or gravel or concrete pavement (Ref 34, p. 47)

. The containment factor values for Source 1 are provided in Table 10

.

TABLE 10 CONTAINMENT SOURCE 1

Containment Description Containment Factor Value Reference s
Gas release to air: Not scored

Particulate release to air: Not scored

Release to ground water: Monitoring well samples provide evidence of hazardous substance migration from the source area, and none of the following is known to be present

, nor were documented by deep so il borings, at the source: liner, maintained engineered cover, functioning and maintained run

- on control system and runoff management system, or functioning leachate collection and removal system immediately above a liner. The depth to water at the site r anges from 10.6 to 13.8 feet below the top of monitoring well casings (Ref. 34, p. 57) . Potential dense non

- aqueous phase liquids (DNAPL) were found from approximately 8 to 34.5 feet below ground surface in the vicinity of source 1 (Ref. 34, pp. 36, 91). The tool used to detect DNAPL was designed specifically to detect tar in the subsurface (Ref. 34, p. 17). This suggests DNAPL tar is present below the water table. 10 5, pp. 18, 20, 27, 28 , 33, 34, 35 ; 34, p p. 58 , 60, 86, 88, 91 , 277

- 294

Release through overland migration: Not scored

### Hazardous Waste Quantity Sourc e No: 1

38 Source Characterization 2.4.2 HAZARDOUS WASTE QUANTITY

2.4.2.1.1 Hazardous Constituent Quantity

The hazardous constituent quantity for Source 1 could not be adequately determined according to the HRS requirements; that is, the total ma ss of all Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) hazardous substances in the source is not known and cannot be estimated with reasonable confidence [Ref. 1, pp. 51590

- 51591 (Section 2.4.2.1.1)]. There are insufficie nt historical and current data (Manifests, PRP records, State records, Permits, Waste concentration data, etc.) available to adequately calculate the total or partial mass of all CERCLA hazardous substances in the source and the associated releases from th e 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 Constituent Quantity Assigned Value: Not scor ed

2.4.2.1.2 Hazardous Wastestream Value

The hazardous wastestream quantity for Source 1 could not be adequately determined according to the HRS requirements; that is, the mass of the hazardous wastestreams and CERCLA pollutants and contaminants in the s ource and releases from the source is not known and cannot be estimated with reasonable confidence [Ref. 1, pp. 51591 (Section 2.4.2.1.2)]. There are insufficient historical and current data (Manifests, PRP records, State records, permits, etc.) available to adequately calculate the total or partial 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 releas es from the source to calculate the hazardous wastestream quantity for Source No. 1 with reasonable confidence. Hazardous Wastestream Quantity Assigned Value: Not scored

2.4.2.1.3 Volume

The information available is not sufficient to adequately support e valuation of the volume for Source 1 as the full depth of contami nation was not determined by sampling. Volume Assigned Value: 0 (Ref. 1, Section 2.4.2.1.3).

2.4.2.1.4 Area

As documented in Tables 4 and 9 of this HRS documentation record, soil sample s collected from Source 1 revealed the presence of numerous PAH compounds at concentrations above background levels

, documenting an area of soil contamination. Table 5 of this HRS documentation record summarizes observations of contaminated soil. Prior t o the November 2013 and June 2014 removal activities

, t he area of contaminated soil was estimated to be 12, 447 square feet

, as shown on Figure 2 of this HRS documentation record and using the samples summarized in Tables 4 and 9 of this HRS documentation

r ecord.

Because contaminated soils were excavated during the November 2013 and June 2014 removal activities in accordance with the Administrative Settlement Agreement and Order on Consent for Removal Action (Ref. 46, pp. 4, 9, 28, 37, 38 ), a conservative value of unknown, but greater than 0 is assigned as the Source 1 area assigned value to account for an unknown amount of soil contamination remaining at the source, as well as releases from the source to s hallow ground water that were not addressed as par t of the removal activities.

Area of S ource (ft 2 

### ): Unknown, but >0

### Hazardous Waste Quantity Sourc e No: 1

39 Source Characterization Equation for Assigning Value (Table 2

- 5): A/34,000 Area Assigned Value: >0

2.2.4.3 Source Hazardous Waste Quantity Value

The source hazardous waste quantity value is assigned the value for area of contaminated soil.

Highest assigned value assigned from Table 2

- 5: >0

### 40 Source Characterization Table 11 provides a summary of the Source 1 hazardous waste quantity factor value and containment factor values.

TABLE 11 SUMMARY OF SOURCE DESCRIPTIONS

Source Num ber Source Hazardous Waste Quantity

Value Source Hazardous Constituent

Quantity Complete? (Y/N) Containment Factor Value by Pathway

GW (Table 3

- 2) SW Air

Overland/flood

(Table 4

- 2) GW to SW (Table 3

- 2) Gas (Table 6

- 3) Particulate (Table 6

- 9)

1 

### >0 N 10 NS NS NS NS

Notes: GW = Ground water NS = Not scored SW = Surface water



### Description of Other Possible Sources

There are no other known source areas at the INL&P facility

.

### 41 GW

- General 3.0 GROUND WATER MIGRATION PATHWAY

3.0.1 GENERAL CONSIDERATIONS

Si te Geology

The EE/CA completed for INL&P included a n investigation of ground water and site geology. Electrical conductivity ( EC) probing was conducted to delineate the lithology of the subsurface of INL&P . EC probing is able to distinguish fine

- grained from coarse

- grained unconsolidated material that may indicate preferential pathways for contaminant migration. The probes were intended to be advanced to bedrock; however, bedrock was not encountered before refusal within glacial till. The depth to till is between 14.6 and 31.1 feet bgs (Ref. 34, p. 15).

The geology at INL&P is described in the EE/CA as follows: Alluvium and glacial till underlay INL&P. The upper portion of the alluvium consists mostly of stiff, low plasticity sandy or silty clay. Th e lower portion of the alluvium is composed of a medium

- to course

- grained sand with a few discontinuous clay lenses. One particular clay lens is present within the sand layer underneath a portion of INL&P at approximately 26 feet bgs. This clay lens was identified in EC probes EC

- 9 and EC

- 3 and was also observed in the soil boring for monitoring well MW

- 2B. The probes and monitoring well locations are shown in Figure 2

- 1

, page 75 of Reference 34. However, the lens was not identified in any other EC
pro be or soil boring , which indicat es the lens is not continuous throughout INL&P. Underlying the alluvium is glacial till composed mostly of very stiff sandy or silty clay. S oft, sandy clay was encountered below the sandy alluvium a t monitoring well MW

- 3B

. This material was distinctly different than the glacial till encountered at all of the other monitoring well locations. Based on the response of probe EC

- 02, it appears this material is approximately 8 feet thick. Because of the high clay content, this material is likely not a preferential pathway and does not alter the general site conceptual model (Ref. 34, p. 23). Geologic cross sections developed from boring and EC logs are shown on Figures 3

- 1, page 77, and 3

- 2, page 78 of Reference 34.

Geo tech nical testing conducted as part of the EE/CA indicates that the bulk density and hydraulic conductivity of the shallow soil at the facility as determined from a sample collected from 5 to 7 feet bgs using American Society for Testing and Materials ( A ST M ) M ethod D5084

- 00 was lean clay with an average hydraulic conductivity of 3.73 x 10 - 5 

### centimeters per second (cm/sec) and a bulk density of 95.6 pounds per cubic f oo t (Ref. 34, p. 24). The laboratory data sheet associated with the geotechnical testing is loc ated in Appendix I (page 438) of Reference 34.

Ground water levels were measured in all the IN L& P monitoring wells during the EE/CA field investigation in July 2009. The depth to ground water at each well relative to the top of casing and the correspondi ng ground water elevation are presented in Table 3

- 1

, page 57 of Reference 34. The ground
water levels were used to generate potentiometric surface maps for water levels measured from both the “A” and “B” wells, Figure 3

- 3

, page 79 of Reference 34

, and Fi gure 3

- 4

, page 80 of Reference 34. These maps indicate an east/southeast direction of ground water flow in the surficial aquifer across INL&P . The water levels indicate a negligible vertical gradient at wells MW

- 1A/B, MW

- 4A/B, and MW

- 6A/B. There is a sl ight upward gradient at wells MW

- 2A/B and MW

- 3A/B, indicating that the screened intervals are separated by a less permeable layer. This thin clay layer was observed and recorded in the boring logs. A slight downward gradient exists at wells MW

- 5A/B and M W

- 7A/B, which are the two southernmost wells. A downward gradient is typical of an area of recharge within the aquifer and indicates downward flow (Ref. 34, p. 26).

The EE/CA included a slug test data evaluation to calculate hydraulic conductivity. Cal culated hydraulic conductivity ranges from 1.41 x 10 - 3 

### cm/sec in well MW

- 1A to 2.11 x 10 - 1 

### cm/sec in well MW

- 5B. The

### 42 GW

- General average hydraulic conductivity of the upper portion of the alluvial sand is 9.18 x 10 - 3 

### cm/sec and 1.56 x 10 - 2 

### cm/sec for the lower portio n of the alluvial sand . The horizontal flow velocities were calculated to be 45 feet per year in the upper portion of the alluvial sand and 86 feet per year in the lower portion of the alluvial sand (Ref. 34, p. 26)

. The slug test and ground water calcul ation sheets are presented in Appendix H (page 386) of Reference 34.

Ground Water Migration Pathway Description

Aquifer/Stratum 1 (uppermost): Surficial Alluvial Deposits

The soils at INL&P are classified as Muir silty clay loam. These soils are nearly level (0 to 1 percent slopes) on low stream terraces. The Muir silty clay loams are well drained, have surface runoff classified as slow, and have moderate permeability. These soils formed from silty alluvium in the flood plain of the Elkhorn River (Ref . 11, pp. 7, 9, 10, 11).

Norfolk is located on the alluvial plains of the Elkhorn River and its tributary, the North Fork of the Elkhorn River (Refs. 3; 11, p. 9). The unconsolidated materials underlying Norfolk consist of Quaternary age stream alluvium (sand, gravel, and silty clay) deposited by the Elkhorn River and North Fork of the Elkhorn River (Ref. 11, p. 3). Static water level measured during the ESI conducted in 2000 was approximately 14 feet bgs (Ref. 5, pp. 57, 58). The northwestern portion o f Norfolk is underlain by glacial till and loess deposits, creating gently sloping to steep hills (Ref. 11, pp. 3, 9, 11). The unconsolidated materials are of Quaternary age and have an approximate thickness of 40 to 5 0 feet in the North Fork Elkhorn Rive r flood plain (Refs. 3; 10, pp. 34, 35; 11, p. 3). The alluvial and glacial deposits form a surficial aquifer, from which nearby private wells and municipal wells near the West Water Treatment Plant draw potable water supplies . The primary sources of gro und water in Madison County are the sands and gravels of the surficial alluvial deposits that overlie the bedrock through most of the county. W ell depths i n the Elkhorn Valley commonly range from 50 to 150 feet. Depths to water generally range from 10 to 20 feet near the Elkhorn River to as much as 50 feet along the valley sides. In the upland

, as much as 200 feet of loess and till may overlie the sand and gravel of the surficial alluvial deposits . Wells depths in the uplands generally range from 175 to 300 feet and water levels generally range from 75 to 175 feet (Ref. 11, p. 3).

Aquifer/Stratum 2 ( lowest ): Niobrara Chalk

The unconsolidated sands and gravels of the surficial alluvial deposits are underlain by Cretaceous age Niobrara chalk (Ref s . 11, p. 3 ; 10, pp. 12, 35 ). This unit is estimated to be from 100 to 200 feet thick and consists of marine chalky shale and chalk that is light

- to medium

- gray and yellow (Ref. 18, pp. 3, 4). Ground water is derived from open fractures , crevices, and solutio n cavities within the chalk , and the water withdrawn from the chalk is replaced by recharge from the overlying unconsolidated surficial alluvial deposits (Refs. 18, p. 3; 11, p. 4). The Niobrara chalk is not extensively used for water supplies (Ref. 11, p . 4). The unconsolidated sands and gravels of the surficial alluvial deposits and the chalk formation are considered interconnected and will be evaluated as one hydrologic unit. Municipal well logs for G

- 49313 (west), G

- 70116 (east) indicate that sands d irectly over lie chalk rock or are separated by a thin (less than three

- feet

- thick) stringer of clay (Refs. 10, pp. 12, 34, 35 , 87, 88, 93 ) A generalized stratigraphic column of the local geology is presented as Figure 5

- 1 in the ESI report (Ref. 5, p. 30). Table 1 2 provides a summary of aquifers evaluated at the site.

As shown in R eference 3, all target wells within the four mile target distance limit are within the broad alluvial floodplains of the North Fork Elkhorn River and the Elkhorn River. There are no known geologic features that completely transect the surficial alluvial deposits and Niobrara Chalk formation.

### 43 GW

- General TABLE 1 2 SUMMARY OF AQUIFER(S) BEING EVALUATED

Aquifer Number Aquifer Name Is Aquifer Interconnected with Upper Aquifer within 2 mi les? (Y/N/NA) Is Aquifer Continuous within 4

- mile TDL? (Yes/No) Is Aquifer Karst? (Yes/No)

1 Surficial Alluvial Deposits (Alluvium) Not applicable Yes No

2 Niobrara Chalk Yes Yes No

### 44 GW

– Likelihood of Release 3.1 LIKELIHOOD OF RELEASE

3.1.1 OBSERVED RELEASE

Direct Observat ion

Soil borings collected from the facility contained tar. The depth to water at the site ranges from 10.6 to 13.8 feet below the top of monitoring well casings (Ref. 34, p. 57). Potential dense non

- aqueous phase liquids (DNAPL) were found from approxim ately 8 to 34.5 feet below ground surface in the vicinity of S ource 1 (Ref. 34, pp. 36, 91). The tool used to detect DNAPL was designed specifically to detect tar in the subsurface (Ref. 34, p. 17). This suggests DNAPL tar is present below the water tabl e.

Chemical Analysis

Establishing an observed release by chemical analysis requires analytical evidence of a hazardous substance in the medi um at a concentration significantly above the background level. If the background concentration is not detected ( or is less than the detection limit), an observed release is established when the sample measurement equals or exceeds its own sample quantitation limit (SQL) and that of the background sample. If the SQL cannot be established, the EPA contract

- required q uantitation limit (CRQL) is used in place of the SQL for sample s analy z e d under the EPA Contract Laboratory Program (CLP), or the detection limit for sample not analy z e d under the EPA CLP (Ref. 1, Section 2.3, Table 2

- 3). All hazardous substances listed i n the ground water observed release tables meet these criteria.

Basis for Chemical Analysis:

Data collected during the ESI and the EE/CA ground water investigation from on

- facility monitoring wells and temporary monitoring wells document an observed rel ease by chemical analysis to the interconnected shallow surficial alluvial deposits (alluvium) and Cretaceous age Niobrara chalk aquifer systems (Refs. 5; 34, p. 85). The data from the ESI and EE/CA investigations used to document an observed release to t he interconnected shallow surficial alluvial deposits and Cretaceous age Niobrara chalk systems are discussed in the sections below. This aquifer system will be referred to as the interconnected alluvium and Niobrara chalk aquifer system

.

An observed r elease by chemical analysis also is supported by the 1992 sampling conducted by HDR Engineering, Inc. During the 1992 sampling, three monitoring wells (MW

- 101, MW

- 104, and MW

- 106) were sampled and analyzed for VOCs, SVOCs, metals, and cyanides (Ref. 7, pp

. 7, 18, 30, 45, 47 , 58

- 74 ). However, this investigation is not used to document an observed release to the aquifer because the data are more than 1 5 years old.

Expanded Site Inspection: Observed Release by Chemical Analysis :

As documented in the sec tions below, the data collected during the ESI documents an observed release to the interconnected alluvium and Niobrara chalk aquifer systems by extensive distribution of clean background temporary monitoring wells screened in the same aquifer at simila r depths as the release wells (Ref. 5, pp. 19, 56

- 64, 68

- 72, 130 )

. The ESI field activities were conducted by E&E between March 19 and 25, 2000

, and were completed in accordance with the site

- specific QAPP (Refs. 5, p. 13; 13). During the ESI field work, 2 0 ground water samples were collected and analyzed using the mobile laboratory in accordance with the START MLP QAPP. F ourteen DPT ground water confirmatory samples were submitted to the EPA Region 7 laboratory for confirmation analysis (Ref. 5, pp. 13, 1 8, 19, 56

- 64, 68

- 72, 83, 130

, 206

- 209). All municipal well samples and private well samples were submitted for analysis (Ref. 5, p p . 13 , 130 ). Appendi ces B and C of Reference 5 provide a copy of the chain

- of

custody form , field sheets, and analytical d ata (Ref. 5, p p

. 55

- 2 10 ). Samples collected by START were analyzed by the EPA Region 7 laboratory under ASR number 539, activity number TJC13 (Ref. 5, pp.

### 45 GW

– Likelihood of Release 128

, 131). The laboratory analyzed the samples in accordance with EPA Region 7 SOP 1640.1A, EPA R egion 7 Laboratory Quality Assurance Project Plan (Ref. 13, p. 29). SVOC s were analyzed in accordance the EPA Region 7 SOP 3230.2B for extraction and analysis of water and solids for SVOC

, dated February 1995. VOC s were analyzed in accordance with EPA Re gion 7 SOP 3230.1C, GC/MS Analysis for VOCs

, dated October 1993. The metals were analyzed in accordance the EPA Region 7 SOP 3122.2B, analysis for metals by TJA ICAP 61, April 1995 (Ref. 13, p. 31). The data were validated in accordance with procedures o utlined i n Section 6.5 of Reference 13 (Ref. 13, p. 34 ) . The chain

- of custody form for the samples collected during the ESI and sent to the EPA Region 7 laboratory is provided as Appendix B of Reference 5, pages 124 to 127. The logbook notes documenting s ampling are provided as Appendix D (page 211) of Reference 5.

During the ESI, ground water samples were collected from six municipal wells (wells 1 through 5, and 10), and four private or commercial wells (Ref. 15, p p

. 1, 2, 9). All samples from privat e and municipal wells were analyzed by the EPA Region 7 laboratory for drinking water VOCs (Ref s

. 5, p p. 128, 130, 132, 149, 155, 160; 15, p p. 2, 9). In addition, ground water samples were collected fr om temporary monitoring wells. Twenty locations were sampled from a 4

- foot

- long screen at depths of either 18 to 22, 29 to 33, 33 to 37, or 36 to 40 feet bgs (Ref. 15, pp. 2, 6). A ground water sample was collected a t each location and analyzed by an on

- site field laboratory for benzene and target PAH compo unds including naphthalene, benzo(a)anthracene, benzo(b) fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene (Ref. 15, p. 2). Fourteen samples from 12 of these locations were also submitted to the EPA Region 7 laboratory for confirmation analysis (Ref. 15, p. 9). A ground water sample was also collected from monitoring well PG

- 1. It is believed that this well is the same as well MW

- 101 that was installed and sampled as part of the 1992 investigation (Refs. 15, pp. 2, 6, 9; 13, p. 20; 7, p. 7). The oth er two monitoring wells installed previously could not be located during the ESI (Ref. 5, p. 19).

### 46 GW

– Likelihood of Release Expanded Site Inspection Background Concentrations:

During the ESI, background concentrations in temporary monitoring wells are represented by wells GP

- 4, GP

- 5, GP

- 8, GP

- 11, and GP

- 30. As shown on Figure 3

- 2 of the ESI report, wells GP

- 4, GP

- 5, and GP

- 8 are all located west

- northwest of INL&P (Ref. 5, p. 18). GP

- 11 is located northeast and GP

- 30 is located south (Ref. 5, p. 18). Temporary wells GP

- 4, GP

- 5, GP

- 11, and GP

- 30 were screened at a depth of 18 to 22 feet bgs and w ell GP

- 8 was screened at a depth of 33 to 37 feet bgs (Ref. 5, pp. 57, 58, 59, 70, 72). The temporary wells were not surveyed ; therefore, an elevation of the screened interval is not p rovided. The field sheets documenting the sample collection date and time are provided in Appendix B of Reference 5 ( Ref. 5, p. 55) . Appendix B also provides the chain

- of

- custody records for the background samples.

These wells were chosen as backgroun d wells because the y are upgradient or in some cases side gradient of Source 1 (Ref s . 15, Figure 2 , p. 6 ; 5, pp. 18, 19, 21, 29, 31, 41; 34, pp. 79, 80 ). Temporary wells GP

- 4, GP

- 5, GP

- 11, GP

- 8, and GP

- 30 are located approximately, 0.06, 0.04, 0.14, 0.19 a nd 0.04 mile upgradient /cross

- gradient from Source 1

, respectively. (See Figure 2 of this HRS documentation record; Ref. 15, p. 6) The ground water samples collected from the background and release wells were collected from similar depths in the aquifer ( screened intervals)

, as documented in Tables 13 and 1 5 below

. The field sheets rather than logbooks were used to document sample collection time and locations in Tables 13 and 1 5

. The samples were collected during the same time frame using the same sampl e collection procedures and analytical methods (Ref. 5 , p p . 19 , 21 ). The construction details for the background monitoring wells are provided in Table 1 3 below

. Table 1 4 below summarizes the concentrations of hazardous substances detected in the backgro und wells. The samples were assigned laboratory sample numbers on the chain

- of

- custody form (Ref. 5, pp. 124

- 127 ; 15, pp. 9, 10) . The laboratory sample numbers are used on the analytical data sheets to identify the sample.

TABLE 1 3 2000 EXPANDED SIT E INSPECTION BACKGROUND MONITORING WELL CONSTRUCTION DETAILS

Sample Identification Laboratory Sample Identification Screened Interval (ft bgs) Date Reference

GP

- 4 2 18

- 22 3/22/00 5, pp. 57, 130
GP

- 5 3 18

- 22 3/22/00 5, pp. 58, 130
GP

- 11 15 18

- 22 3 /25/00 5, pp. 70, 130
GP

- 30 17 18

- 22 3/25/00 5, pp. 72, 130, 234
GP

- 8 4 33

- 37 3/24/00 5, pp. 59, 130, 216, 229, 233

Notes: bgs Below ground surface ft Feet GP Geoprobe

### 47 GW

– Likelihood of Release TABLE 14

2000 EXPANDED SITE INSPECTION BACKGROUND CONCENTRATIONS

Sample Identi fication Hazardous Substance Concentration ( μ g/L) Sample Quantitation Limit ( μ g/L) Reference s

GP

- 4 (Laboratory Sample 2) Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(g,h,i)perylene Benzo(k)fluoranthen e Chrysene Fluoranthene Fluorene Indeno(1,2,3

- c,d)pyrene 2

- Methylnaphthalene Naphthalene Phenanthrene Pyrene 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 5, pp. 57, 124, 130, 133, 134 , 135 ; 45, pp. 4, 5

GP

- 5 (Laboratory Sample 3) Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(g,h,i)perylene Benzo(k)fluoranthene Chrysene Fluoranthene Fluorene Indeno(1,2,3

- c,d)pyrene 2

- Methylnaphthalene Naphthalene Phenanthrene Pyrene 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 5, pp. 58, 124, 130 , 133, 134; 45, pp. 7, 8

### 48 GW

– Likelihood of Release TABLE 14

2000 EXPANDED SITE INSPECTION BACKGROUND CONCENTRATIONS

Sample Identi fication Hazardous Substance Concentration ( μ g/L) Sample Quantitation Limit ( μ g/L) Reference s

GP

- 11 (Laboratory Sample 15) Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(g,h,i)perylene Benzo(k)fluoranthene Chrysene Fluoranthene Fluorene Indeno(1,2,3

- c,d)pyrene 2

- Methylna phthalene Naphthalene Phenanthrene Pyrene 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 5, pp. 70, 127, 130, 143, 144, 217; 45, p. 41, 42

GP

- 30 (Laboratory Sample 17) Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(g,h,i)perylene Benzo(k)fluoranthene Chrysene Fluoranthene Fluorene Indeno(1,2,3

- c,d)pyrene 2

- Methylnaphthalene Naphthalene Phenant hrene Pyrene 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 5, pp. 72, 130, 147, 148; 45, pp. 47, 48

### 49 GW

– Likelihood of Release TABLE 14

2000 EXPANDED SITE INSPECTION BACKGROUND CONCENTRATIONS

Sample Identi fication Hazardous Substance Concentration ( μ g/L) Sample Quantitation Limit ( μ g/L) Reference s

GP

- 8 (Laboratory Sample 4) Acenaphthene A cenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(g,h,i)perylene Benzo(k)fluoranthene Chrysene Fluoranthene Fluorene Indeno(1,2,3

- c,d)pyrene 2

- Methylnaphthalene Naphthalene Phenanthrene Pyrene 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 U 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 5, pp. 59, 130, 133, 134; 45, pp. 10, 11

Notes: GP Geoprobe ground water sample ND Not detected μg/L M icrograms per lite r U Not detected at or above the reportable level shown (Ref. 5, p. 129).

### 50 GW

– Likelihood of Release 2000 Expanded Site Inspection

- Contaminated Samples:

During the ESI, releases of hazardous constituents related to INL&P were reported in municipal, monitoring

, and temporary mon itoring wells

, all located hydrologically downgradient of INL&P

. During the ESI, temporary and permanent monitoring well samples were analyzed for low detection limit VOCs, dissolved metals, total cyanid e, and SVOCs (Ref. 15, p. 9). Samples from private and municipal wells were analyzed for drinking water VOCs, ethylene dibromide (EDB), dibromochloropropane (DBCP), total and dissolved metals, total cyanide, SVOCs, and PAHs (Ref. 15, p. 9). The temporary monitoring wells that contained elevated levels of contaminants were GP

- 3, GP

- 23, and GP

- 28. All of these wells were located east and downgradient of INL&P (see Figure 2 page 6 of Reference 15 ) (Ref. 15, p. 6). Temporary wells GP

- 23, and GP

- 28 were screened at a depth of 18 to 22 fe et bgs (Ref. 5, pp. 60 , 62). The temporary wells were not surveyed ; therefore, an elevation of the screened interval is not provided. The construction details for the release monitoring wells are provided in Table 1 5 below

. Table 1 6 below summarizes the concentrations of haz ardous substances detected in the release wells. The samples were assigned laboratory sample numbers on the chain

- of

- custody (Ref s . 5, pp. 124

- 127 ; 15, pp. 9, 10)

. Direction of g round water flow at INL&P is east

- southeast (Ref. 5, pp. 29, 31). Therefo re , the release wells are located hydrologically downgradient of Source 1

. The sample identifications are used on the analytical data sheets to identify the sample.

TABLE 1 5 2000 EXPANDED SITE INSPECTION RELEASE MONITORING WELL CONSTRUCTION DETAILS

Sample Identification Laboratory Sample Number Screened I nterval (ft bgs) Date Reference s

GP

- 3 1 20

- 24 3/21/00 15, pp. 6, 9; 5, pp. 56, 130

GP

- 23 5 18

- 22 3/24/00 15, pp. 6, 9; 5, pp. 60, 130

GP

- 28 7 18

- 22 3/24/00 15, pp. 6, 9; 5, pp. 62, 130

Not es: b gs Below ground surface f t Feet GP G eoprobe g round water sample MW Monitoring well

### 51 GW

– Likelihood of Release TABLE 16 2000 EXPANDED SITE INSPECTION RELEASE CONCENTRATIONS

Sample Identification Hazardous Substance Concentration Sample Quantitation Limit (SQL) Background Co ncentration A ( SQL) (see Table 1 4 ) Reference s Units: (μg/L)

GP

- 3 (Laboratory Sample 1) Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(b)fluoranthene Benzo(g,h,i)perylene Benzo(k)fluoranthene Chrysene Fluoranthene Fluoren e Indeno(1,2,3

- c,d)pyrene 2

- Methylnaphthalene Naphthalene Phenanthrene Pyrene 360 700 300 160 130 60 43 77 190 310 230 42 140 400 1,200 530 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND ( 2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) 5, pp. 56, 130, 133, 134; 45, pp. 1, 2

GP

- 23 ( Laboratory Sample 5) Acenaphthene Acenaphthylene Naphthalene 33 5.4 49 2.0 2.0 2.0 ND (2) ND (2) ND (2) 5, pp. 60, 130, 136, 137, 138 ; 45, pp. 13, 14

GP

- 28 (Labora tory Sample 7) Acenaphthene Acenaphthylene Anthracene Benzo(a)anthracene Benzo(a)pyrene Benzo(k)fluoranthene Chrysene Fluoranthene Fluorene 2

- Methylnaphthalene Naphthalene Phenanthrene Pyrene 290 280 85 21 25 15 25 69 130 92 690 280 97 10 10 10 10 10 10 10 10 10 10 10 10 10 ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) ND (2) 5, pp. 62, 130, 136, 137, 138; 45, pp. 19, 20, 21

Notes:
A The background concentrations and sample quantitation limits (SQL) are documented in Table 1 4 of this HRS documentation record. As documented in Table 1 4, the SQL for the semivolatile organic compounds such as acenaphthene is 2 μg/L. GP Geoprobe ground water sample ND Not d etected μg/L Micrograms per liter

### 52 GW

– Likelihood of Release Ground Water Sampling

- E ng ineering E valuation /C ost A nalysis (EE/CA)

The EE/CA field investigation occurred in November and December 2007, June and July 2009, and January 2010. The field activities were completed as specified in the w ork p lan, t echnical m emorandum 1, and f ield s am pling p lan ( Refs . 37; 38; 40 ). Table 2

- 1 outlines significant deviations to the planned work (Ref. 34, p p . 14 , 55 ).

The ground water field investigation included advancing laser

- induced fluorescence ( LIF ) and ground water probes; installing and develop ing monitoring wells; measuring ground water elevations; collecting ground water samples; and surveying. Sampling included collection of ground water samples from direct

- push probes and from newly installed monitoring wells for chemical analysis. The EE/ CA field activities were designed to gather data to better define and characterize the subsurface geology and site hydrogeology and the approximate extent of DNAPL and dissolved

- phase ground water contamination at the INL&P (Ref. 34, p. 14). Aquifer testi ng also was performed (Ref. 34, p. 16).

Fourteen ground water probes were advanced on INL&P and three samples were collected from each probe

, for a total of 42 ground water samples

, t o delineate the horizontal and approximate vertical extent of ground w ater contamination (Ref. 34, pp. 17, 29). The samples were analyzed for PAHs by SW

- 846 Method 8270

- SIM and for VOCs by SW

- 846 Method 8260B. All PAH data were reported as Level II quality data. Figure 2

- 1

, page 75 of Reference 34 shows the probe location s (Ref. 34, p. 17).

In November and December 2007

, ground water probes were advanced to refusal within the glacial till. A n attempt was made to collect a sample a t the refusal depth . If no water was present, the probe was retracted and a sample was col lected at the interface of the sand and till . The probe was then retracted to the midpoint of the sand unit or to a depth where potential DNAPL was indicated by LIF probing to collect the “intermediate” sample. The probe was retracted a third time to col lect the sample at the top of the sand unit. This procedure was used for the ground water probes advanced west of 6th Street. Although the potentiometric surface was measured at approximately 12 feet bgs, it was within a silty clay unit that did not prod uce much water. Therefore, the shallow sample was collected at the top of the sand unit (Ref s. 34, pp

. 17, 18 , 85, 277

- 294 ).

W ater was present in the till unit f or ground water probe samples collected east of 6th Street . Therefore, the “deep” sample was collected from the point of probe refusal in the till. The probe was then retracted and a sample was collected from the interface of the sand and till to evaluate whether contamination was sinking and pooling on top of the till downgradient from the s ite . The probe was again retracted to the top of the sand

, where the third, shallow sample was collected (Ref. 34, p. 18).

Monitoring wells were installed in soil borings with 81⁄2

- inch outside diameter (OD), 41⁄4

- inch inside diameter hollow stem augers. E ach boring was continuously sampled by driving 2

- foot split

- spoon samplers. The borings were logged to record stratigraphy and visible contamination and were screened for VOCs with a PID and the results recorded on the boring logs. Two nested monitoring wells were installed at each location to monitor the upper and lower portions (designated with the letters “A” and “B”) of the surficial aquifer. Table 2

- 2

, page 56 of Reference 34 lists the depth and screened interval for each newly installed well. All wells are constructed of 2

- inch OD Schedule 40 polyvinyl chloride pipe with 0.010

- inch wide factory slots. Shallow wells have 9.5

- foot screens and the deep wells have 4.8

- foot screens (Ref. 34 p. 18). Ground water samples were collected in July 2009 (Ref . 34, pp. 85, 295

– 315, 341

– 354).

The EE/CA ground water sampling investigation was performed in July 2009. All monitoring wells were purged and sampled in accordance with the QAPP (Ref. 38) using low

- flow sampling procedures. Before sampling, the wells were allowed to equilibrate with the surrounding formation and ground water level s

were measured . In addition, wells MW

- 2A and MW

- 2B were measured for light and dense nonaqueous

### 53 GW

– Likelihood of Release phase liquid. Also d uring purging, field measurements [dissolved oxyge n (DO), oxidation

- reduction potential (ORP), pH, temperature, turbidity, and specific conductivity were recorded. N o field parameters were measured f or wells where there was an oily sheen on the water (wells MW

- 2A and MW

- 2B) (Ref. 34, p. 19). The ground water sampling forms for each well are presented in Appendix G of Reference 34.

After wells were purged , ground water samples were collected from each monitoring well for chemical analys i s of VOCs by SW

- 846 Method 8260B, PAHs by SW

- 846 Method 8270

- SIM, selected total metals (arsenic, barium, cadmium, chromium, and lead) by SW

- 846 Method 6010B, and total and amenable cyanide by SM 4500CN

- E/4500CN

- G. All BTEX, PAH

, and cyanide data were reported as Level IV quality data. Existing monitoring well MW

- 104 w as not found during the EE/CA field investigation (Ref. 34, pp. 19, 20).

Fifteen ground water samples were collected from 14 ground water monitoring wells. All samples were analyzed for BTEXs, PAHs, and inorganic constituent s (arsenic, barium, cadmium, chromium, lead, and cyanide) (Ref. 34, p. 29). The analytical results from the monitoring well samples are used to document an observed release to ground water. The samples collected from the ground water probes are not used to document an observed rele ase to ground water because the ground water samples were not collected from properly installed monitoring wells. The ground water probe samples contained VOCs and PAHs (Ref. 34, pp. 3 0 , 31).

EE/CA DNAPL Delineation :

The EE/CA also included delineatio n of the approximate horizontal and vertical extent of potential DNAPL in the saturated portion of the subsurface. The delineation involved advancing 18 probes equipped with a LIF tool designed specifically to detect tar in the subsurface. The LIF tool d etects tar by emitting a laser light that causes electrons in the tar to excite and fluoresce. A sensor on the LIF tool then measures the intensity of the fluorescence to provide a qualitative result on the amount present. In general, the stronger the si gnal, the more likely tar is present. The LIF probe locations were selected based on the locations of historical MGP structures from Sanborn Maps and historical investigation results (Refs. 34, p. 17; 37, p. 8) . The locations of the LIF probes are shown on Figure 2

- 1

, page 75 of Reference 34

, and the LIF logs and data files are included in Appendix D of Reference 34. In addition, three soil probes (SP

- 5, SP

- 6, and SP

- 8) were advanced and continuously sampled and logged t o verify data obtained with the LI F probes (Ref. 34, p. 17).

Probes LIF

- 01, LIF

- 03, LIF

- 06, LIF

- 07, LIF

- 08, and LIF

- 09 were advanced near historic al MGP
structures. As shown in Table 4

- 6

, page 63 of Reference 34, these probes indicate potential DNAPL from approximately 8 to 34.5 feet bgs . No DNAPL was identified below approximately 25 feet in the probes advanced south of the alley that bisect s INL&P

, likely a result of the presence of the clay lens identified during EC probing and previously discussed. However, probes LIF

- 02, LIF

- 04, LI F

- 14, and LIF

- 15, east of INL&P , indicate potential DNAPL below 25 feet. Probes LIF

- 02, LIF

- 04, LIF

- 14, and LIF

- 15 are located approximately 60 feet, 112 feet, 130 feet, and 135 feet from Source 1 (Figure 2 of this HRS documentation record; Ref. 34, p. 75 )

. This finding suggests that the clay layer is not continuous east of 7th Street. T he thickness of the potential DNAPL indicated by the LIF probes decreases significantly east of INL&P . No DNAPL was indicated in probes LIF

- 05, LIF

- 10, LIF

- 11, LIF

- 12, LI F

- 13, LIF

- 16, LIF

17, or LIF

- 18

, indicat ing that DNAPL has not migrated downgradient of these locations and is confined
to INL&P (Ref. 34, pp. 36, 37). The LIF logs are presented in Appendix C of Reference 34.

The approximate extent of DNAPL contaminati on as of 2009 is shown in Figure 4

- 11

, page 91 of Reference 34.

### 54 GW

– Likelihood of Release Background Concentrations:

E ach monitoring well was installed as nested pairs one well screened in the shallow and one screened in the deeper portions of the alluvium d uring the 2009 EE/CA ground water investigation . Monitoring wells screened in the shallow portion of the alluvium were assigned the prefix A

, and the monitoring wells screened in the deeper portion have the prefix B. Well MW

- 1A is the background well for the shallow portion of the alluvium

, and MW

- 1B is the background well for the deep portion of the alluvium. The locations of the monitoring wells are shown in Reference 34

, Figure 2

- 1 page 75. These wells were chosen as background because the y are upgradient of Source 1 (R ef. 34, Figure 3

- 3, p. 79 and Figure 3

- 4, p. 80). The ground water samples from the background and release wells were collected from similar depths in the aquifer (screened intervals)

, as documented in Table 1 7 below . The samples were collected during th e same time frame using the same sample collection procedures and analytical method (Ref s . 34, p. 19; 37; 38). The construction details for both the background and the release monitoring wells are provided in Table 1 7 below.

The concentrations of hazar dous substances detected in the background wells are summarized in Table 1 8 for the wells screened in the shallow portion of the aquifer and in Table 1 9 for the wells screened in the deeper portion of the aquifer.

### 55 GW

– Likelihood of Release TABLE 1 7 EE/CA MONITORING WELL DEPTH A ND SCREENED INTERVAL

Monitoring Well A Sample Date Total Depth Screened Interval TOC Elevation Depth to Water Ground Water Elevation Reference 34 (ft bgs) (ft bgs) (ft above msl) (msl) (ft btoc) (msl)
MW

- 1A 07/08/2009 20.2 10.3

– 19.8 1502.9

– 15 1 2 .4 15 22.35 10.62 1511.73 pp. 56, 57, 295 , 341, 372 MW

- 1B 07/08/2009 28.0 23

– 27.8 1495.0

– 1499.8 1522.31 10.60 1511.71 pp. 56, 57, 296, 297 , 342, 373 MW

- 2A 07/07/2009 26.4 16.5

– 26 1495.9

- 1505.4 1521.43 11.41 1510.02 pp. 56, 57, 298 , 343, 374 MW

- 2B 07/07/20 09 34.5 29.5

– 34.3 1487.9

– 1492.7 1521.55 11.41 1510.14 pp. 56, 57, 299, 300 , 344, 375 MW

- 3A 07/06/2009 26.1 16.2

– 2 5.7 1498.1

– 1507.6 1523.00 13.73 1509.27 pp. 56, 57, 301 , 345, 376 MW

- 3B 07/06/2009 38.0 32.8

– 37.6 1486.2

– 1491.0 1523.48 13.67 1509.81 p p. 56, 57, 302, 303 , 346, 377 MW

- 4A 07/07/2009 25.0 15.1

– 24.6 1499.1

– 1508.6 1523.22 13.73 1509.49 pp. 56, 57, 304 , 347, 378 MW

- 4B 07/07/2009 33.0 28

– 32.8 1490.8

– 1495.6 1523.23 1 3 .72 1509.51 pp. 56, 57, 305, 306 , 348, 378 MW

- 5A 07/07/2009 20.3 10.4

– 1 9.9 1502.9

– 1512.4 1522.40 13.77 1508.63 pp. 56, 57, 307 , 349, 380 MW

- 5B 07/07/2009 35.6 30.6

– 35.4 1487.4

– 1492.2 1522.34 13.80 1508.54 pp. 56, 57, 308, 309 , 350, 381 MW

- 6A 07/07/2009 23.2 13.3

– 22.8 1498.0

– 1507.5 1520.54 12.75 1507.79 pp. 56, 57, 310 , 351, 382 MW

- 6B 07/07/2009 32.3 27.3

– 32.1 1488.7

– 1493.5 1520.51 12.71 1507.80 pp. 56, 57, 311, 312 , 352, 383 MW

- 7A 07/07/2009 23.1 13.2

– 22.7 1496.8

– 1506.3 1519.17 11.76 1507.41 pp. 56, 57, 313 , 353, 384 MW

- 7B 07/07/2009 32.5 27.5

– 32.3 1487.2

– 1492 .0 1519.11 11.84 1507.27 pp. 56, 57, 314, 315 , 354, 385
Notes:
A Wells designated with an “A” monitor ground water within the upper portion of the surficial aquifer. Wells designated with a “B” monitor ground water at the b ase of the surficial aquifer. MW

- 1A is the background well for wells screened in the shall ow portion of the alluvium

, and well MW

- 1B is the background well for wells screened in the deeper portion of the alluvium. bgs B elow ground surface btoc Below top of casing ft Feet msl M ean sea level MW Monitoring well TOC T op of casing

### 56 GW

– Likelihood of Release TABLE 1 8 EE / CA BACKGROUND CONENTRATION

– SHALLOW GROUND WATER

Sample Identification Laboratory Sample Identification Hazardous Substance Concentration (μg/L) Method Detection

Limit (μg/L) Reference 34
MW

- 1A MW1AWOP1P Benzo(a)pyrene ND 0.051 p. 544 MW

- 1A MW1AWOP1P Benzo(b)fl u oranthene ND 0.051 p. 544 MW

- 1A MW1AWOP1P Benzo(g,h,i)perylene ND 0.051 p. 544 MW

- 1A MW1AWOP1P Dibenzo(a,h)anthracene ND 0.051 p. 544 MW

- 1A MW1AWOP1P Fluoranthene 0.12 0.051 p. 544 MW

- 1A MW1AWOP1P Phenanthrene ND 0.051 p. 544
Notes

< Analyte was not detected at or above the method detection limit, which is presented. MW Monitoring well μg/L Microgram per liter ND Analyte was not detected at or above the method detection limit (Ref. 34 , p. 60)



### TABLE 1 9 EE / CA BACKGROUND CONENTRATION

– DEEP GROUND WATER

Sample Identification Laboratory Sample Identification Hazardous Substance Concentration (μg/L) Method Detection Limit (μg/L) Reference 34

MW

- 1B MW1BWOP1P Acenaphthene ND 0.05 p. 546 M W

- 1B MW1BWOP1P Acenaphthylene ND 0.05 p. 546 MW

- 1B MW1BWOP1P Benzo(a)anthracene ND 0.05 p. 546 MW

- 1B MW1BWOP1P Benzo(a)pyrene ND 0.05 p. 546 MW

- 1B MW1BWOP1P Benzo(b)fl u oranthene ND 0.05 p. 546 MW

- 1B MW1BWOP1P Benzo(g,h,i)perylene ND 0.05 p. 546 MW

- 1B MW1BWOP1P Benzo(k) f luoranthene ND 0.05 p. 546 MW

- 1B MW1BWOP1P Fluoranthene 0.087 0.05 p. 547 MW

- 1B MW1BWOP1P Naphthalene 0.13 0.05 p. 547 MW

- 1B MW1BWOP1P Phenanthrene ND 0.05 p. 547

Notes:

< Analyte was not detected at or above the method detection lim it, which is presented. MW Monitoring well μg/L Microgram per liter ND Analyte was not detected at or above the method detection limit (Ref. 34, p. 60)

### 57 GW

– Likelihood of Release Release Concentrations:

The concentrations of hazardous substances that meet the criteria for document ing an observed release to ground water are summarized in Table 20 for wells screened in the shallow portion of the alluvium and in Table 21 for wells in the deep portion of the alluvium. Tar

- saturated sand was encountered in the soil boring retrieved from well MW

- 2B (Ref. 34, pp. 299, 300). Tar was encountered in the boring from well MW

- 6B (Ref. 34, p. 311).

TABLE 20 EE/CA RELEASE CONENTRATION

– SHALLOW GROUND WATER (Background Monitoring Well MW

- 1A)

Sample Identification Hazardous Substance Concentrat ions (adjusted concentration) (μg/L) Method Detection Limit (μg/L) Background Concentration (μg/L) (see Table 18 ) Reference 34
MW

- 2A MW

- 6A Benzo(a)pyrene 1.4 0.090 0.052 0.051 <0.051 p. 550
p. 568 MW

- 2A MW

- 6A Benzo(b)fl u oranthene 1.4 0.10 0.052 0.051 <0. 051 p. 550
p. 568 MW

- 2A Benzo(g,h,i)perylene 0.57 0.052 <0.051 p. 550 MW

- 2A Dibenzo(a,h)anthracene 0.12 0.052 <0.051 p. 551 MW

- 2A MW

- 3A MW

- 4A MW

- 6A MW

- 7A Fluoranthene 10.9 1.6 3.8 0.80 0.58 0.052 0.051 0.054 0.051 0.05 0.12 p. 551
p. 555
p. 559
p. 568
p

. 572 MW

- 2A MW

- 3A MW

- 4A MW

- 6A Phenanthrene 37.6J (3.76) 11.7 37.1J (3.71) 3.2 0.052 0.051 0.054 0.051 <0.051 p. 551
p. 555
p. 559
p. 568
Note s : MW

- 1A is the background well for these wells. The background and release wells are screened in the shallow portion of the alluvium. The ground water samples with estimated concentrations (J laboratory data qualified) are adjusted according to the EPA fact sheet Using Qualified Data to Document an Observed Release and Observed Contamination, Reference 44. The concentrations are divided by the adjustment factor value because the bias i s unknown (Ref. 44, p. 8). The adjustment factors are benzene 1.64 and phenanthrene 10 (Ref. 44, pp. 11, 14, 15). The concentration in parenthesis is the adjusted concentrations

. < Analyte was not detected at or above the method detection limit, which is presented. ( ) Adjusted concentration (Ref. 44) J Estimated concentration (Ref. 34, pp. 60, 615) , the concentration in parenthesis is the adjusted concentration (Ref. 44). MW Mo nitoring well μg/L Microgram per liter

### 58 GW

– Likelihood of Release TABLE 21 EE/CA RELEASE CONENTRATION

– DEEP GROUND WATER (Background Monitoring Well MW

- 1B)

Sample Identification Hazardous Substance Concentrations (adjusted concentration) (μg/L) Method Detection Limit (μg/L) Backg round Concentration (μg/L) (see Table 19 ) Reference 34
MW

- 2B MW

- 4B MW

- 5B MW

- 7B Acenaphthene 30.3J (8.34) 86.3J (23.77) 0.81 77.8J (21.43) 0.052 0.054 0.053 0.052 <0.05 p. 553 p. 561 p. 566 p. 574 MW

- 2B MW

- 3B MW

- 4B MW

- 5B MW

- 7B Acenaphthylene 20.8 1.6 4.5 0.055

3.8 0.052 0.052 0.054 0.053 0.052 <0.05 p. 553 p. 557 p. 561 p. 566 p. 574 MW

- 2B Benzo(a)anthracene 0.45 0.052 <0.05 p. 553 MW

- 2B Benzo(a)pyrene 0.18 0.052 <0.05 p. 553 MW

- 2B Benzo(b)fl u oranthene 0.19 0.052 <0.05 p. 553 MW

- 2B Benzo(g,h,i)perylene 0.073 0.052 <0.05 p. 553 MW

- 2B MW

- 3B MW

- 4B MW

- 7B Fluoranthene 9.5 0.37 2.8 0.61 0.052 0.052 0.054 0.052 0.087 p. 553 p. 557 p. 561 p. 574 MW

- 2B MW

- 4 B MW

- 7B Naphthalene 5.4 48.9J (4.89) 19.1 0.052 0. 05 4 0.052 0.13 p. 553 p. 5 61 p. 574 MW

- 2B MW

- 3B MW

- 4B MW

- 5B MW

- 7B Phenanthrene 42.5 1.3 38.9J (3.89) 0.41 21.2J (2.12) 0.052 0.052 0.054 0.053 0.052 <0.05 p. 553 p. 557 p. 561 p. 566 p. 574
Notes: MW

- 1B is the background well for these monitoring wells. The background and release wells are screened in the d eep portion of the alluvium. The ground water samples with estimated concentrations (J laboratory data qualified) are adjusted according to the EPA fact sheet Using Qualified Data to Document an Observed Release and Observed Contamination, Reference 44. The concentrations are divided by the adjustment factor value because the bias in unknown (Ref. 44, p. 8). The adjustment factors are acenaphth ene 3.63 ; naphthalene 10; and phenanthrene 10 (Ref. 44, pp. 14

, 1 5 ).

< Analyte was not detected at or above the method detection limit, which is presented. ( ) Adjusted concentration (Ref. 44) J Estimated concentration (Ref. 34, pp. 60, 615 )

, the concentration in parenthesis is the adjusted concentration (Ref. 44). MW Monitoring well μg/L Microgram per liter

### 59 GW

– Likelihood of Release Attri bution

The Iowa

- Nebraska Light and Power Company operated under numerous names in Norfolk, Nebraska, from about 1907 through the mid

- to late

- 19 40 s (Refs. 6, p. 3; 8, pp. 8, 9; 9. During this time

, the facility operated as a manufactured gas plant (Ref. 7, pp. 3, 5). Operations at the facility used fossil fuel (coal and oil) as a feedstock to produce a combustible gaseous product that was used for lighting and heating (Refs. 8, p. 9; 9, pp. 3

- 5). The manufacturing process generated several byproducts including tars, sludges, tar liquors and ammonia liquor, spent iron oxide ash, slag, and clinkers (Ref. 19, p p . 3

- 32). The coal tars are comp o sed of polycyclic aromatic hydrocarbons ( PAHs ) , phenolic compounds, light aromatic compounds, and small quanti ties of inorganic constituent s (Refs. 8, pp. 9, 11; 19, pp. 9 through 14 ). In the early years from 1900 to 1924, the facility used a Tenney and Springer process (Ref. 9, pp. 2

- 24 ). Between 1926 and 1930

, the process was described as water gas (Ref. 9, pp. 25

- 29 ). Between 1932 and 1935

, the process was described as carbureted water gas (Ref. 9, pp. 30

- 33 ).

Generators produced a combustible gas using coke, steam, and oil products (Ref. 39, p. 6). As the gas cooled through the production process, c oal tar would fall from suspension in the gas and become a waste product (Ref. 39, p. 6). A scrubber was used to condense the gas (Ref. 39, p. 6). Coal tar was ultimately separated from the condensate water (Ref. 39, p. 6). Purifier boxes were used to r emove sulfides and cyanides from the cool gas. Iron oxides were mixed with fluffing material (primarily wood chips, sawdust and corncobs) in the purifier boxes to provide for additional removal of water vapor and coal tar with the associated hydrogen sulf ide and cyanide (Ref. 39, p. 6). After the gas was manufactured, it was stored in gas holders. Coal tar residuals were also present in the gas holders (Ref. 39, p. 6)

. Some of the waste resulting from the production of the manufactured gas, including c oal tar, was sold. Some wastes were disposed of at the facility (Ref. 39, p. 7). Coal tar is primarily composed of PAHs

, phenolic compounds, light aromatic compounds, various inorganics and various sulfides (Ref. 39, pp. 6, 7). In December 1990, Ecology and Environment, Inc. (E&E), completed a preliminary assessment (PA) at INL&P to assess potential sources of contamination. The PA provided site

- related background information, estimates of possible waste quantities produced, and a summary of nearby targ ets (Ref. 6, pp. 1 to 4). The PA postulated that PAH and cyanide waste may have been disposed of to the ground (Ref. 6, p. 8). In June 1992, HDR Engineering Inc. (HDR) of Omaha, Nebraska, conducted a site investigation (SI) of INL&P for Minnegasco, Inc. Eighteen soil samples were collected from six soil borings, and four ground water samples were collected from three monitoring wells installed during field operations. The six borings referred to as NOR

- 101 through NOR

- 106, were located near former facil ity features to investigate the possibility that releases of associated wastes to soil had occurred in the past (Ref. 7, pp. 6, 7, 8). As documented in S ection 2 of this HRS documentation record, soil samples collected at the facility contained elevated c oncentrations of the same constituents as were reported in ground water samples collected from on

- site monitoring wells and temporary monitoring wells. Background wells did not indicate other potential sources of coal tar related hazardous constituents in the immediate site vicinity. There are no other known source areas at the INL&P facility

. The EE/CA described 29 leaking underground storage tank sites within 0.5 mile of the facility and 16 underground storage tanks within 0.25 mile (Ref. 34, pp. 12, 13

, 98, 99, 100). These leaking underground storage tanks may be contributing petroleum related constituents to area. Ground water flow is to the east, south east (Ref. 34, pp. 79, 80, 85

- 88). Most of the USTs and/or LUST sites are located downgradient of both the source and temporary wells used to establish the observed release and/or are located upgradient of background samples used in the scoring (Ref. 34, p. 105 ; Figure 2 of this HRS documentation record ).

Evidence of releases from the former MGP op erations to ground water is evidenced in the presence of DNAPL in ground water underlying and downgradient of the contaminated soil source

, as documented in

### 60 GW

– Likelihood of Release the EE/CA ground water investigation ( Ref. 34, pp. 36, 37 ). The approximate extent of DNAPL
contam ination is shown in Figure 4

- 11

, page 91 of Reference 34.

Hazardous Substances Released

Acenaphthene Benzo(a)pyrene Chrysene 2

- Methylnaphthalene Acenaphthylene Benzo(b)fluoranthene Fluorene Naphthalene Anthracene Benzo(g,h,i)perylene Fluoranthene Phena nthrene Benzo(a)anthracene Benzo(k)fluoranthene Indeno(1,2,3

- c,d)pyrene Pyrene

Ground Water Observed Release Factor Value: 550

### 61 GW

– Wast e Characteristics 3.2 WASTE CHARACTERISTICS

3.2.1 Toxicity/Mobility

Table 2 2 summarizes the toxicity and mobility values and combined f actor value for the hazardous substances associated with Source 1. All hazardous substances listed in Table 2 2 have been documented in either soil or ground water samples from S ource 1. These hazardous substances were detected at concentrations significa ntly exceeding background levels.

TABLE 2 2 TOXICITY/MOBILITY FACTOR VALUES

Hazardous Substance Source Number Toxicity Factor Value Mobility Factor Value* Does Hazardous Substance Meet Observed Release?** Toxicity/ Mobility Factor Value (Ref. 1, Table 3

- 9) Reference Acenaphthene 1 10 1* Yes 10 2, p. 3 Acenaphthylene 1 1 1* Yes 1 2, p. 3
Anthracene 1 10 1* Yes 10 2, p. 3 Benzo(a)anthracene 1 1,000 1* Yes 1,000 2, p. 3 Benzo(a)pyrene 1 10,000 1* Yes 10,000 2, p. 4 Benzo(b)fluoranthene + 1

--- 1* Yes

-- - 2, p. 4 Benzo(g,h,i)perylene 1 0 1* Yes 0 2, p. 4 Benzo(k)fluoranthene 1 100 1* Yes 100 2, p. 4 Chrysene 1 10 1* Yes 10 2, p. 5
Fluoranthene ** * 1 100 1* Yes 100 2, p. 4
Fluorene 1 100 1* Yes 100 2, p. 7 Indeno(1,2,3

- c,d)pyrene 1 1,000 1* Yes 1,000 2, p. 9
2

- Methylnaphthalene 1 1,000 1* Yes 1,000 2, p. 9 Naphthalene 1 1,000 1* Yes 1,000 2, p. 9
Phenanthrene 1 1 1* Yes 1 2, p. 10 Pyrene 1 100 1* Yes 100 2, p. 10
Notes:

* Liquid, non

- karst mobility factor value used, or if substance was found in an observed release to ground water
, then a mobility factor value of 1 is assigned (Ref. 1, Sec. 3.2.1.2).

** See section 3.1.1 of this HRS documentation record

*** This compound is listed as it s synonym benzo(j,k)fluorene in Reference 2

+ Compound not li sted in Reference 2



### Benzo(a)pyrene is the hazardous substances with the highest toxicity and mobility factor value

, of 10,000.

Toxicity/Mobility Factor Value: 1x10 4 

### (Ref. 1, Table 3

- 9)

### 62 GW

– Wast e Characteristics 3.2.2 Hazardous Waste Quantity

Table 2 3 provides a summary of t he source hazardous waste quantity values.

TABLE 2 3 SUMMARY OF SOURCE HAZARDOUS WASTE QUANTITY VALUES

Source Number Source Type Source Hazardous Waste Quantity
1 Contaminated Soil 

### >0

Sum of Values: >0

In accordance with Section 2.4.2.2, a minimum value of 10 was used for the Hazardous Waste Quantity Factor Value because Hazardous Constituent Quantity has not been adequately determined for Source 1

, and none of the targets for the ground water pathway is subject to Level I or Level II concentrations (Ref. 1, Sec. 2.4.2.2).

Hazardous Waste Quantity Factor Value: 10 (Ref. 1, Section 2.4.2.2)

3.2.3 Waste Characteristics Factor Category Value

Toxicity/Mobility Factor Value: 10,000 Hazardous Waste Quantity Factor Value: 10

Toxicity/Mobility Fact or Value × Hazardous Waste Quantity Factor Value: 100,000 or 1 × 10 5



### Waste Characteristics Factor Category Value: 18 (Ref. 1, Table 2

- 7)

### 63 GW

– Targets 3.3 TARGETS

The public water supplies for the City of Norfolk are provided by the City of Norfolk public water s upply system consisting of two water treatment plants supplied by two well fields. The two fields have a total of 1 1 active wells (Ref s . 17, pp. 1, 2 ; 27; 41; 43 ). The water treatment plants are referred to as the east and west water treatment plants (Re f s . 17, p. 1; 41, p. 1). Wells serving the west water treatment plant range in depth from 5 0 to 65 feet below ground surface (Ref. 17, pp. 1

- 8, 14). The last right

- hand column of Reference 17, pages 1 and 2, identif ies the plant that receives the flow from the supply wells. N umber 001 indicates the east water treatment plant (facility number 001) and number 002 indicates the west water treatment plant (facility number 002) (Ref. 1 7, pp. 1, 2). Wells serving the east water treatment plant range in dept h from 101 to 120 feet below ground surface (Ref. 17, pp. 2, 11

- 13). Wells serving the west water treatment plant are screened in unconsolidated sands and gravel (Ref. 10, pp. 1

– 12 , 40

- 48, 62, 63 ). A boring log for a well serving the east water treat ment plant indicates that the well is finished as an uncased and unscreened hole in chalk formation (Ref. 10, pp. 34, 35).

Eight municipal wells (wells 681, 682, 692, 691, 752, 751, 921

, and 20031) are associated with the west treatment plant, and three wells (wells 281, 471

, and 551) are associated with the east treatment plant (Ref s

. 17

, p p

. 1, 2 ; 43, pp. 3, 4 ). Two other municipal wells (wells 291 and 301) formerly were associated with the east treatment plant and have been taken out of service becau se of contamination thought to be associated with a leaking underground storage tank (LUST) (Refs. 43, p p. 1, 2 , 3 ; 20, p. 2; 34, pp. 12, 13, 7 4, 98

- 100 ; 10, pp. 18, 22). Municipal 291 is currently being used as a remediation well, and municipal well 30 1 was idled because of benzene co ntamination (Ref s . 20, p. 2 ; 43, p. 1 ). According to the City Water superintendent, there are 9,352 service connections (Ref. 36). A ccording to the City Water superintendent, the population served is 24,210 (Refs. 12, p. 1; 36). The City also sells water to two subdivisions outside the city limit, the Eastern Heights, subdivision where water is provided to about 80 homes and the Suburban Acres subdivision where the city provided water to about 30 homes (Ref. 36). In total t he city provide s water to a city and subdivision population of 24,472 (Ref. 36)

. Table 24 presents information for the C ity of Norfolk municipal wells.

TABLE 2 4 CITY OF NORFOLK WATER SUPPLY WELLS

State Registration

Number Other Identifier Status, Water Treatment Plant Served Location Township, Range, Section Total Depth (feet) Screen depth ( feet bgs ) Capacity (gpm) Date Drilled Reference s

G

- 029258 68

- 1 (681) Well 7 Active, West 24N, 2W, 25ad 50.67 30'8"

- 50'8" 750 03/09/68 17, pp. 1, 3; 10, pp. 1, 2

G

- 029259 68

- 2 (682) Well 1 Active, West 24N, 2W, 25ad 59 29

– 59 1,000 03/12/68 17, pp. 1, 4; 10, pp. 3, 4

G

- 049057 69

- 2 (692) Well 9 Active, West 24N, 1W, 30cb 57 27

– 57 1,000 10/30/69 17, pp. 2, 5; 10, pp. 5

- 7; 21, p. 4

G

- 049058 69

- 1 (691) Active, West 24N, 1W, 30cb 57 27

– 57 1,000 10 /2 9 / 69 17, pp. 2, 6; 10, pp. 8, 9;
G

- 049312 75

- 2 (752) Active, West 24N, 1W, 30cd 55.5 20

– 56 1,000 04/18/75 17, pp. 2, 7; 10, pp. 10, 11

, 61 ;

21, p. 4

### 64 GW

– Targets TABLE 2 4 (Continued) CITY OF NORFOLK WATER SUPPLY WELLS

State Registration

Number Other Identifier Status, Water Treatment Plant Served Location Township, Range, Section Total Depth (feet) Screen depth ( feet bgs ) Capacity (gpm) Date Drilled Reference s

G

- 049313 75

- 1 (751) Well 10 Active, West 24N, 1W, 30ca 55.5

– Unknown 1,000 04/24/75 17, pp. 2, 8; 10, pp. 12, 13; 21, p. 4

G

- 070112 21

- 1 (291) Well 1 Inactive, East 24N, 1W, 26bb 130 Not Reported 930 08/29/29 17, pp. 2, 9; 10, pp. 18

- 21; 21, p. 4

G

- 070113 30

- 2 (301) Well 2 Inactive, East 24N, 1W, 26bb 127 Not Re ported 860 10/14/30 17, pp. 2, 10; 10, pp. 22

- 25; 21, p. 4
G

- 070114 26

- 3 (281) Well 3 Active, East 24N, 1W, 26bb 94 (120) Not Reported 520 08/21/28 17, pp. 2, 11; 10, pp. 26

- 29; 21, p. 4
G

- 070115 47

- 4 (471) Well 4 Active, East 24N, 1W, 26bb 101 Not Reported 670 10/11/47 17, pp. 2, 12; 10, pp. 30

- 33; 21, p. 4
G

- 070116 54

- 1 (551) Well 5 Active, East 24N, 1W, 26bb* 117 45

– 117 1

, 220 02/05/55 17, pp. 2, 13; 10, pp. 34, 35; 21, p. 4
G

- 074818 (921) (Well 12) Active, West 24N, 1W, 31 65 40

– 60 800 03 /04/92 17, pp. 2, 14 ; 10, pp. 40, 41, 42,

47, 48
G

- 122246 (20031) Active, West 24N, 1W, 31 69. 5 60

– 67 4,000 08/17/02 17, pp. 2, 15 ; 10, p p

.

62

, 63

Notes:

* The well registration form indicates the well is in section 27 (Ref. 10, p. 34). The wells loca tion in section 27 is substantiated by the off

- site sample location map in the ESI (Ref. 5, p. 18) and by other consultants work in Norfolk (Ref s . 30, pp. 2

– 7 ; 31, p. 2 ). bgs Below ground surface
gpm G allons per minute



### In addition to the city population served, the Norfolk public water supply also serves the primary and secondary schools of the Norfolk p ublic school system (Refs. 22; 2 5 , pp. 13, 17, 18, 19, 20, 23, 24, 28, 31, 41, 47, 48, 50, 51, 53, 54, 58, 59, 60 , 61, 66 ). (Note: Reference 25 provide s the sampling points [SP] for the City of Norfolk distribution system. ) According to on

- line data from 2013

- 2014, t he Norfolk school district has a student enrollment of 4,162 stud ents and 2 70 staff (Ref. 24, pp. 3, 5 )

. Current information for students, faculty and staff indicates a population of 4,814 (Ref. 36). The system also serves the Norfolk Catholic Schools

, with a 2013

- 2014 enrollment of 639 students and a staff of 4 0 (Refs. 24, p. 4, 6 ; 25, p p

. 1 2 , 27, 49, 58, 60 )

. Current staff and student pop ulation is 669 (Ref. 36). The system serves St. Paul Lutheran Elementary school ( 2013

- 2014 enrollment of 98 students and 4 staff ) (Refs. 24,

### 65 GW

– Targets p. 8 ; 25, p. 10 ). Current staff and student population is 154 (Ref. 36). In addition

, the following post

seconda ry education institutions are served by the system : the Northeast Community College (enrollment of 5, 035 ) (Ref s . 2 5 , p. 20 ; 26, p. 9 ). The student population presented for Northeast Community college also includes several satellite campuses. Current stud ent enrollment for the Norfolk campus is 2,954, and faculty and staff is 1,100 for a total of 4,054 (Ref. 36). Northeast Community College is identified as Tech College in Reference 25. The college is located in the City of Norfolk and is served by the City of Norfolk public water supply system ( Ref. 35 )

. In total, the system serves at least 34, 163 residents and student s and staff in the C ity of Norfolk. This number represents the city and two subdivision populations served by the system (24, 472 ) and t he sum of the students and staff provided above (Ref. 36 )

. According to the city, water from the east and west treatment plants is part of a common distribution system. The combined pumping capacity for the system is 10,000 gallons per minute (Ref s . 27 ; 43, p. 1 ). Based on the well capacities presented in T able 2 4 above , no one well contributes more than 40 percent of the total demand to the system ; therefore , the population served by each well is apportioned equally among the 11 active wells

, for a po pulation per well of 3, 1 05 (Ref. 1, Section 3.3.2). All 11 wells were considered eligible. The two closed wells were not considered. It should be noted that the capacities listed for the wells in Table 24 were reported on well registration forms complete d at the time of installation and may not correspond to the actual current pumping rates of the wells (Ref. 27)

. Other public drinking water supply wells serve the area outside of the City of Norfolk. Information obtained from the well logs for those w ells is summarized in Table 2 5 below

. These wells are shown on Reference 3. As shown on Reference 3, a ll wells are located within the same alluvial floodplain as the city of Norfolk wells. A review of the well logs provided in Reference 10 show s that th e drinking water supply wells within a 4 mile radius of INL&P are completed or screened within alluvium, the alluvium and chalk, or chalk. Because ground water moves freely between the alluvium and chalk, the ground water within both of these formations i s evaluated as a single hydrologic unit, the interconnected alluvium and Niobrara chalk aquifer system , as documented earlier in the HRS documentation record. Therefore, the populations served by each of the public water supply wells obtain drinking water supplies from the interconnected alluvium and Niobrara chalk aquifer system . The populations served by each well are summarized in Section 3. 3

. 2 .4

, Table 2 7

.

TABLE 2 5 PUBLIC WATER SUPPLIES WITHIN 4 MILES OF SOURCE 1

(EXCLUDING THE CITY OF NORFOLK SUPP LY WELLS)

Owner State Registration Number Other Identifier Total Depth Screen depth ( feet bgs ) Capacity (gpm) Date Drilled Reference Norfolk Regional Center G

- 068492 Well #5 94 feet 3 inches 69

- 94 390 06/11/1956 10, pp. 64, 66

Norfolk Regional Center G

- 068493 Well #7 66 feet 50

- 66 470 08/31/1967 10, pp. 68, 70

Norfolk Regional Center G

- 068494 Well #6 56 feet 40

- 56 520 08/29/1967 10, pp. 72, 74, 75

Madison County SID#3 G

- 073538 Well 681 90 feet 38

- 90 75 09/28/1968 10, pp. 76, 78, 79

Madison Cou nty SID#3 G

- 043601 Well 751 96 feet 60

- 96 500 12/19/1974 10, pp. 80, 82

Sherwood Medical (currently Covidien) G

- 102698 Well 621 69 feet 59

- 69 350 05/1962 10, pp. 83, 84, 85, 86, 87, 88

### 66 GW – Targets TABLE 2 5 PUBLIC WATER SUPPLIES WITHIN 4 MILES OF SOURCE 1

(EXCLUDING THE CITY OF NORFOLK SUPP LY WELLS)

Screen State Registration Other Total depth Capacity Date Owner Number Identifier Depth ( feet bgs ) (gpm) Drilled Reference
Sherwood Medical G- 102699 Well 751 70 feet 5 3 - 67 100 11/1975 10, pp. 89, 90, (currently Covidien) 91, 92, 93 Sleepy Hollow Acres G

- 119312

-- NA NA 20 1996 10, p. 94
Notes: bgs Below ground surface
gpm Gallons per minute NA Not available



### 3.3.1 Nearest Well

The closest drinking water well to the INL&P is Norfol k municipal well 5 , registration number G0700116 (Ref . 15, p. 6). Reference 30 page 2 clearly shows that city water well 5 is located between First and Second Street and Norfolk avenue and Madison Avenue. This well was measured at 2,530 feet or 0. 48 mile east of the Source 1 (Ref s. 3; 30, p. 2 29 ).

Well ID: Municipal Well 5 Level of Contamination (I, II, or potential): Potential If potential contamination, distance from the source in miles: The Norfolk Municipal well 5 is located between 1 st 

### and 2 nd 

### Streets and Norfolk and Madison Avenues (Ref. 15, p. 6). The location of the well is more precisely shown on figures from a 1998 preliminary subsurface assessment report prepared for the Nebraska Department of Environmental Quality (Ref. 30, pp. 2 - 7). The distance from this well to sample location SB- 3 at the east ern edge of the INL&P is 2,530 feet or 0.48 mile (Ref. 29). In accordance with Section 3.3.1 and Table 3-11 of the HRS rule, a nearest well factor value of 18 is assigned (Ref. 1, Section 3.3.1).

Nearest Well Factor Value: 18 (Ref. 1, Table 3 -11)

### 67 GW

– Targets 3.3.2 POPULATION

3.3.2.1 Level of Contamination

No Level I or Level II concentrations attributable to the site have been documented at this time.

3.3.2.2 Level I Concentrations

Not Scor ed.

3.3.2.3 Level II Concentrations

Not scored.

3.3.2.4 Potential Contamination

The public water supply system for the City of Norfolk includes 11 active permanent municipal wells (Ref s . 17, pp. 1, 2 ; 27; 41 ). These wells are reported to range in depth from 50 to 130 feet bgs (Ref. 17, pp. 3

- 14). The city has two water treatment facilities referred to as the east and west treatment plants (Ref s . 17, p. 1 ; 41, p. 1 ). Eight municipal wells (wells 681, 682, 692, 691, 752, 751, 921

, and 20031) are associated with the west treatment plant, and three wells (wells 281, 471 and 551) are associated with the east treatment plant (Ref. 17, pp. 1, 2). Two other municipal wells (wells 291 and 301) formerly were associated with the east treatment plant and have been taken out of service because of contamination thought to be associated with a LUST (Refs. 17, p. 2; 20, p. 2; 10, pp. 18, 22 ; 34, pp. 12, 13, 74, 98

– 100; 43 ). Municipal well 1 is currently being used as a remediation well, and municipal well 2 was idled because of benzene c ontamination (Ref. 20, p. 2). The municipal water supply serves the entire population of Norfolk (Ref. 12, p. 1 ). According to the City Water superintendent, the population served is 24,210 (Refs. 12, p. 1; 36). The City al so sells water to two subdivisions outside the city limit, the Eastern Heights, subdivision where water is provided to about 80 homes and the Suburban Acres subdivision where the city provided water to about 30 homes (Ref. 36). In total the city provided w ater to 24,472 people (Ref. 36)

.

In addition to the city population served, the Norfolk public water supply also serves the primary and secondary schools of the Norfolk public school system (Refs. 22; 25, pp. 13, 17, 18, 19, 20, 23

, 24, 28, 31, 41, 47 , 48, 49, 50, 51, 53, 54, 58, 59, 60 , 61, 66 ). (Note: Reference 25 provides the sampling points [SP] for the City of Norfolk distribution system. According to on

- line data from 2013

- 2014, t he Norfolk school district has a student enrollment of 4,162 stud ents and 2 70 staff (Ref. 24, pp. 3, 5 ). Current information for students, faculty and staff indicates a population of 4,814 (Ref. 36). The system also serves the Norfolk Catholic Schools, with an enrollment of 639 students and a staff of 4 0 (Refs. 24, p. 4, 6 ; 25, p p

. 1 2 , 27, 49, 58, 60 ). Current staff and student population is 669 (Ref. 36). The system serves St. Paul Lutheran Elementary school ( 2013

- 2014 enrollment of 98 students and 4 staff ) (Refs. 24, p. 8 ; 25, p. 10). Current staff and student pop ulation is 154 (Ref. 36). In addition, the following post

- secondary education institutions are served by the system: the Northeast Community College (enrollment of 5, 035 ) (Refs. 25, p. 20; 26, p. 9 ). The student population presented for Northeast Communi ty college also includes several satellite campuses. Current student enrollment for the Norfolk campus is 2,954, and faculty and staff is 1,100 for a total of 4,054 (Ref. 36). Northeast Community College is identified as Tech College in Reference 25. Th e college is located in the City of Norfolk that is served by the City of Norfolk public water supply system (Ref. 35). In total, the system serves at least 34, 163 residents and student s and staff in the City of Norfolk. This number represents the city a nd two subdivision population s served by the system (24, 472 ) and the sum of the students and staff provided above (Ref. 36 ).

### 68 GW

– Targets According to the city, water from the east and west treatment plants is part of a common distribution system. The combined pump ing capacity for the system is 10,000 gallons per minute (Ref. 27). Based on the well capacities presented in Table 2 4 in Section 3.3, no one well contributes more than 40 percent of the total demand to the system ; therefore

, the population served by each well is apportioned equally among the 11 active wells

, for a population per well of 3, 1 05 (Ref. 1, Section 3.3.2). This population is entered into Table 26 below for each Norfolk well. All 11 wells were considered eligible. The two closed wells were n ot considered.

In addition to the City of Norfolk wells

, there are numerous other community water supplies within the 4

- mile radius of the INL&P facility. The locations of the wells serving these wa ter supplies are documented in R eference 31 and are sho wn on R eference 3. The populatio ns served by these systems

come from Reference 32. Because all wells for each of these system s fall within the same distance ring, apportionment of population has not been determined

. In addition to the populations includ ed in this scoring, there are numerous additional worker populations present within the City of Norfolk community (Refs. 4 7, 4 8).

### 69 GW

– Targets TABLE 2 6 POPULATIONS SERVED BY GROUND WATER
Distance Category

(miles) Well (Well Registration Number) Population Reference Distance

- Weighted Population Value (Ref. 1, Table 3

- 12)

0

- 1⁄4 None Known

1⁄4

- 1⁄2 Norfolk Municipal Wells Well #5 (G

- 070116) Total 1⁄4

- 1⁄2 3, 1 05 3, 1 05 1, Section 3.3.2.4; 3; 31, p. 2 3,233

1⁄2

- 1 Norfolk Municipal Wells Well #3 (G

- 070114) Well #4 (G

- 07 0115)

Total 1⁄2

- 1 3, 1 05 3, 1 05

6, 2 10 1, Section 3.3.2.4; 3 ; 31, p. 2 1, 669
1

– 2 Norfolk Regional Center Well #5 (G

- 068492) Well #7 (G

- 068493) Well #6 (G

- 068494) Madison Co. SID No. 5

Well 022 Well 021

Total 1

- 2 158 158 158

65 65

604 1, S ection 3.3.2.4; 3; 31, pp. 5, 6; 32, pp. 1

- 4

94

2

– 3 Madison Co. SID No. 3 Well 681 (G

- 073538) Well 751 (G

- 043601) Kendall (Covidien) Company

Well 3 (G

- 102698) Well 6 (G

- 102699) Total 2

- 3 187 188

215 215 805 1, Section 3.3.2.4; 3; 31, pp. 7, 8; 32, pp. 5

- 8

68

3

– 4 Norfolk Municipal Wells Well 681 (G

- 029258) Well 682 (G

- 029259) Well 692 (G

- 049057) Well 691 (G

- 049058) Well 752 (G

- 049312) Well 751 (G

- 049313) Well 921 (G

- 074818) Well 20031 (G

- 122246) Sleepy Hollow Acres

Well 21 (G

- 119312) Total 3

- 4 3, 1 05 3, 1 05 3, 1 05 3, 1 05 3, 1 05 3, 1 05 3, 1 05 3, 1 05

120 2 4,960 1, Section 3.3.2.4; 3; 31, pp. 3, 9; 32, p. 9

1,306

Sum of the Distance

- Weighted Population Values: 6,370



### Sum of Distance

- Weighted Population Values: 6,370 Sum of Dis tance

- Weighted Population Values/10: 637 (Ref. 1, Section 3.3.2.4)

Potential Contamination Factor Value: 637

### 70 GW

– Targets 3.3.3 RESOURCES

Ground water within the target distance limit is used for irrigation and commercial food preparation (Refs. 5, p. 224; 28, p p. 16, 24, 25, 59, 66; 10 pp. 36

- 39). The pages cited on R eference 28 indicate irrigation wells irrigate at least five acres of land.

Resources Factor Value: 5

3.3.4 WELLHEAD PROTECTION AREA

Observed ground water contamination lies within the Stat e of Nebraska Department of Environmental Quality

- designated wellhead protection area for the east well field (Ref. 31, p. 2). The wellhead protection program is approved by EPA (Ref. 29 , p. 8 ).

Wellhead Protection Area Factor Value: 20 (Ref. 1, Sec tion 3.3.4)