Full opinion text
FINDINGS OF FACT & CONCLUSIONS OF LAW SINGAL, Chief Judge. This matter came before the Court for the first phase of a bifurcated trial on Plaintiff City of Bangor’s (“City”) claims under both the Resource Conservation and Recovery Act (“RCRA”), 42 U.S.C. § 6972(a)(1)(B), and the Comprehensive Environmental Response, Compensation, and Liability Act (“CERCLA”), 42 U.S.C. § 9607. Notably, Defendant Citizens Communications Company (“Citizens”) has asserted counterclaims against the City under both CERCLA, 42 U.S.C. § 9613(f)(1), and RCRA, 42 U.S.C. § 6972(a)(1)(B). The Court received evidence over the course of twelve trial days in September 2005. Following these trial days, the Court received additional evidence in the form of exhibits, stipulations and one trial deposition. The Court closed the evidentiary phase of this bench trial on October 6, 2005. The Court then provided the parties with an opportunity to file closing briefs and proposed findings of fact and conclusions of law. After receiving these submissions and the responses thereto, the Court held a closing oral argument on December 28, 2005. At issue in this case is an approximately ten acre section of the Penobscot River, known as Dunnett’s Cove, which the City alleges is environmentally contaminated with tar. According to the City, the sole source of this tar is a manufactured gas plant that operated in Bangor from approximately 1852 until at least 1963 (the “Bangor MGP”). The City claims that the Bangor MGP disposed of tar-laden waste-water through the Old Stone Sewer, which discharged directly into Dunnett’s Cove from approximately the mid-1800s until 1967. At this first phase trial, the focus was on whether the preponderance of the evidence supported the City’s factual allegations regarding the tar deposit in Dunnett’s Cove and whether Citizens was, in fact, liable for the alleged tar deposit under either CERCLA or RCRA. In addition to the initial question of liability, the Court’s bifurcated trial plan for this matter contemplated that if, in fact, the Court determined that Citizens was liable under CERCLA, it would also resolve the question of equitable allocation as well as the issues raised by Citizens’ counterclaims under CERCLA and RCRA. In accordance with Federal Rule of Civil Procedure 52(a), the Court now makes the following findings of fact and conclusions of law: I.FINDINGS OF FACT A. The Parties 1. Plaintiff City of Bangor (the “City”) 1. The City is a municipality organized under the laws of the State of Maine. 2. Since 1996, the City has owned certain shoreline property abutting Dunnett’s Cove. This property was formerly owned by the Maine Central Railroad Company and operated as a railyard. (Stipulation # 39 (Docket # 559); Exs. 402, 739.) 3. The City also owns property on the northern end of Dunnett’s Cove on which coal docks once were located. (Ex. 402.) 4. The City’s current ownership interests include the inter-tidal area of Dun-nett’s Cove. (See Rec. Decision (Docket #291) at 14-17; Order Affirming Rec. Decision (Docket # 356).) 5. For the entire period relevant to this case, the City has maintained and operated a system of public drains and sewers for the benefit of the residents and businesses located in the City. (Tr. 1323-24,1343-63; Ex. 843 at 79-81.) 2. Defendant Citizens Communications Company (“Citizens”) 6. Citizens is a corporation organized under the laws of Delaware with a principal place of business in Stamford, Connecticut. 7. Prior to 2000, Citizens Communications Company was known as Citizens Utilities Company. (Stipulation # 9 (Docket # 559).) 8. In 1948, Citizens Utilities Company merged with the Bangor Gas Company and thereby became the owner of the Bangor MGP. (Stipulation # 8 (Docket # 559).) 9. On January 15, 1963, Citizens sold and transferred the Bangor MGP, along with all of its customers and records, to the North American Utility Construction Corporation and the Maine Utility Gas Company. (Ex. 988; Stipulation # 13 (Docket # 559); Tr. 2354.) B. Background Findings With Respect to Tar & Polycyclic Aromatic Hydrocarbons (“PAHs”) 10. PAHs are a combination of chemicals found in the environment that in high levels can be hazardous to humans. In this case, PAHs are the constituents of concern that are driving the cleanup of the Dunnett’s Cove site. (Tr. 1069,1140,1541, 2224.) 11. PAHs are significant constituents of both pyrogenic and petrogenic materials. (Tr. 960.) 12. Petrogenic is a general term used to describe materials produced naturally in the earth, such as crude oil and coal as well as products made with crude oil or coal. (Tr. 904; 957.) 13. Pyrogenic is a term that refers to materials produced at high temperatures with no oxygen. (Tr. 904.) Coal tar and petroleum are pyrogenic materials. 14. When examined visually, materials such as asphalt, creosote, and coal can be mistaken for tar. (Tr. 1486-91.) In other words, even a trained eye cannot definitively identify a material as petrogenic, pyrogenic or, more specifically, as “tar” based purely on visual inspection. (Tr. 904-05,1482.) 15. However, petrogenic and pyrogenic materials have substantially different chemical compositions and can be distinguished from one another via chemical analysis. (Tr. 925-29.) 16. Coal tar and petroleum tar are also chemically distinguishable from one another. (Ex. 389 Slide 6.) 17. Both petroleum tar and coal tar are slightly denser than water. However, petroleum tar is less dense than coal tar, which makes it more likely to form a water emulsion. (Tr. 2164-66.) 18. Tar is generally considered a nonaqueous phase liquid (“NAPL”) that does not mix with water. (Tr. 669.) 19. If tar is cooled below 100-140 degrees Fahrenheit, it becomes viscous and sticky and generally stiffens. Once this happens, tar will no longer float. (Tr. 1950-51.) 20. In general, tar contained in a water emulsion is more buoyant than tar not in such an emulsion. The buoyancy of such a tar-water emulsion is increased when there is only a small amount of tar entrained in a large amount of water. (Tr. 2165-66.) 21. Under certain conditions, NAPLs can travel up through the water column to the surface. In the case of a tar NAPL, this process usually involves a bubble of methane gas trapped within the tar NAPL, which usually occurs under warmer conditions. Once the NAPL reaches the surface, the bubble breaks causing a phenomenon referred to as a “bleb” or “blebbing.” What remains of the tar NAPL will then spread across the surface of the water creating a sheen. This combination of blebbing and sheening is a method by which the PAHs found in tar can move from the bottom of the water column to the surface. Once on the surface, the PAH-containing tar can ultimately come to stick to other objects on or in the water. (Tr. 158-67; Exs. 353-358.) 22. The term “background” level is used to refer to the level of chemicals, such as PAHs found in a sample of sediment or water that is deemed to be not impacted by contamination. This “background” level is then considered as the baseline against which contaminated samples are compared. 23. In urban areas, it is common to find PAH levels ranging from 10 to 120 parts per millions (“ppm”) (AKA milligrams per kilogram). Levels within this range are commonly referred to as “urban background” and are thought to be the result of various urban living conditions, such as runoff from streets and parking lots or residue from commonly used household items. (Tr. 463, 2234.) 24. Runoff from paved and sealed surfaces is a major source of PAHs in urban sediments. (Tr.2055-56.) 25. In this case, a baseline sample taken one mile upstream from Dunnett’s Cove (BGSED-1) was found to have a PAH concentration of 538 parts per million, which actually reflects “substantial PAH contamination” in this upstream area of the Penobscot River. (Tr. 1020.) 26. If the PAH levels in Dunnett’s Cove were within the levels of “urban background,” there would be arguably be no need to cleanup the Cove. However, the sampling completed clearly shows that areas of Dunnett’s Cove have PAH levels that far exceed “urban background” levels. (See, e.g., Ex. 365) (C-56 (17,400 ppm)), Ex. 366 & 366A (C-24-SA (13,180 ppm), C-57 (18,000 ppm), C-58 (25,000 ppm)), Ex. 506 (HARB-3 (109,000 ppm), HARB-4 (97,000 ppm), HARB-21 (162,000 ppm), HASH-7 (541,000 ppm), HAC-114, SI (20,-200 ppm), BP-S3 (103,000 ppm), BP-S4 (110,000 ppm), BP-S5 (132,000 ppm), BP-87 (120,000 ppm), BP-S9 (115,000 ppm).) 27. According to the geologic principle of superposition, it is generally the case that materials deposited first are found layered beneath materials that are deposited more recently. (Tr. 320-21; 1015.) C. The History of the Bangor Manufactured Gas Plant, (the “Bangor MGP”) 1. The Corporate History and Ownership of the Bangor MGP Site 28. In 1850, Chapter 410 of the Private and Special Laws of Maine granted a charter to the Bangor Gas Light Company under which the company’s capital stock was to be “applied exclusively to the manufacture and distribution of gas for the purpose of lighting the city of Bangor.” (Ex. 45A; Stipulation # 6 (Docket # 559).) 29. In 1852, the Bangor Gas Light Company built a manufactured gas plant in Bangor, Maine near the intersection of Main Street and Patten Street (the “Bangor MGP”). (Stipulation # 10 (Docket # 559).) 30. The Bangor Gas Light Company merged with the Penobscot Valley Gas Corporation in 1941 thereby forming a corporation named the Bangor Gas Company. (Stipulation # 7 (Docket # 559).) 31. The Bangor Gas Company was the owner responsible for the operations of the Bangor MGP from 1852 to November 29, 1948. (Stipulation # 11 (Docket # 559).) 32. As a result of the merger of Bangor Gas Company and Citizens Utilities Company on November 29, 1948, Citizens became the owner of the Bangor MGP. Citizens owned the Bangor MGP from November 29, 1948 to January 15, 1963. (Stipulation # s 8 & 12 (Docket # 559).) 33. In early 1963, Citizens sold the entire Bangor MGP, including the business records, facilities, customers and contracts to North American Utility and Maine Utility Gas Company. (Ex. 988; Tr. 2350-52.) 34. From January 15, 1963 until May 17, 1978, the Bangor MGP was owned by Maine Utility Gas Company (“Maine Utility Gas”). (Stipulation # 13 (Docket # 559).) 35. On May 17, 1978, the City acquired what remained of the Bangor MGP and the site on which the Bangor MGP had operated. (Stipulation # 14 (Docket # 559); Tr. 2246.) 36. In or around 1979 or 1980, the City demolished the remaining equipment and fixtures at the site of the Bangor MGP. (Stipulation # 15 (Docket # 559).) 37. In 1996, the Maine DEP certified the completion of the cleanup of the Bangor MGP site and determined that the developers of the site could move forward with plans to develop the site for commercial use. (Ex. 898.) In conjunction with this determination, the City sold a portion of the Bangor MGP site to a development company that constructed a Shaw’s Supermarket, which now operates on the site. (Ex. 402; Tr. 2256.) 38. The City continues to own another portion of the Bangor MGP site, which is now operated as a park and commonly known as the Second Street Park. (Ex. 402.) 2. The Operational History 39. Prior to the establishment of electric energy, manufactured gas plants, including the Bangor MGP, were an important utility that provided manufactured gas, which served as an energy source for lighting as well as cooking and heating. (Tr. 664-65.) 40. From approximately 1852 until 1949, the Bangor MGP manufactured gas from coal. (Stipulation # 24 (Docket # 559); Tr.1947.) This process (hereinafter, the “coal gas process”) created coal tar as a by-product. 41. When the Bangor MGP began its operations, it had a single gas holder (“Holder 1”). (Stipulation # 18 (Docket # 559).) 42. In approximately 1854, a second gas holder (“Holder 2”) was installed at the Bangor MGP. (Stipulation # 19 (Docket # 559).) 43. A third gas holder (“Holder 3”) was later installed in approximately 1897. (Stipulation # 20 (Docket # 559).) 44. In 1901, a fourth gas holder (“Holder 4”) was installed at the Bangor MGP. (Stipulation # 21 (Docket # 559).) 45. The process of manufacturing gas also produced tar that many MGPs sold separately for profit. In order to sell tar, the Bangor MGP would have needed to have a place to settle the tar out of the water used in the gas manufacturing process. (Tr.1954-56.) 46. By approximately 1908, Holder 1 had been converted into a tar well that was used to separate tar from water. (Stipulation # 22 (Docket # 559); Tr. 709-10.) 47. There is no direct evidence that the Bangor MGP had specific equipment devoted to tar separation prior to the conversion of Holder 1 in 1908, although there is evidence of tar sales prior to this date. (Tr. 709-11; 756.) 48. In approximately 1912, a tar separator was installed at the Bangor MGP. (Stipulation # 23 (Docket # 559).) 49. From approximately 1932 until 1949, the Bangor MGP used a carbureted water gas (“CWG”) process to manufacture gas in addition to the coal gas process that had been used since 1852. (Stipulation # 25 (Docket # 559); Tr.1947.) The CWG process generated petroleum tar. (Tr. 2153.) 50. In 1940, a property valuation of the Bangor Gas Company was performed for the Public Utilities Commission. This valuation listed both “sewer piping” and “purification equipment” among the property found on the Bangor MGP site as of that year. (Ex. 83 at MID00712.) 51. By 1941, there is evidence that the Bangor MGP had a tar dehydrator on site. A tar dehydrator would have been used to break the tar water emulsion that was more commonly created during the CWG process. (Tr. 729.) 52. From approximately 1949 until the end of 1963, the Bangor MGP used an oil gas process to manufacture gas. (Stipulation # 26 (Docket # 559); Tr.1947.) The oil gas process also generated petroleum tar. (Tr. 2153.) 53. The Bangor MGP’s conversion to the oil gas process involved unique and innovative conversion of existing equipment. This unique conversion brought many engineers to the Bangor MGP in search of understanding and possibly replicating the conversion. (Tr. 698-99.) 54. In the 1950s, Bangor residents complained to the City Council about “unbearable” odors emanating from the Bangor MGP and from their own sewer connections. (Exs. 23, 24 & 25.) 55. In response to these complaints, the local manager of the Bangor MGP said the company was already investigating ways to eliminate the odors, but noted that “the problem of sewer odors is only a problem of the company’s insofar as the gas plant effluent is contributory.” (Ex. 24.) 56. Ultimately, the Citizens Utility Company, which was then running the Bangor MGP, proposed constructing “a special 1,400 foot six-inch sewer from the plant to the Penobscot River” which would “carry away the waste” that was “thought to be the source of the odor.” Citizens agreed to provide the pipe for this project if the City would provide the installation. (Ex. 25.) There is no evidence that this project was actually undertaken. 57. In 1956, the City Council ordered the City Engineer to investigate and recommend a way to correct “the gas odors that now infiltrate and contaminate the private property connected to [the Davis Brook Sewer] in the vicinity of the Bangor MGP.” (Ex. 92.) 58. The City’s 1956 Annual Report described the installation of “a large running trap” in the Davis Brook Sewer. According to the Report, the trap “was installed in the Citizens Utilities Company yard in order to form a trap above the waste outlet from the gas works operation in an effort to eliminate the odors of the waste from the gas plant penetrating the whole sewer system above it.” The Report noted that there had been “very few complaints about odors from the sewer” after the completion of this project. (Ex. 94 at BGRG0000628; Tr. 1350-52.) 59. In 1964, a stark generator process was installed at the Bangor MGP. Because this process ultimately was not economically efficient, propane air was installed in 1965. 60. One former foreman at the Bangor MGP, “Coke” Jordan, reported to the MDEP that the Bangor MGP did, at one point, have a drain pipe that connected an underground settling tank to the Davis Brook Sewer. According to Mr. Jordan, after the Bangor MGP added a baffled cement wash tank in or around 1951-1952, this drain pipe was disconnected. (Ex. 103.) 61. There is no direct evidence proving the Bangor MGP was connected to the Davis Brook Sewer. (Tr. 463-64, 1360-61, 1374-75,1378-79.) 3. The Wastewater & the Tar 62. All three of the processes for manufacturing gas at the Bangor MGP (i.e., the coal gas process, the CWG process and the oil gas process) produced wastewater. (Exs. 378; 379; 380; 586; 587 & 588.) 63. Although some MGPs operated without discharging any of their wastewa-ter (Tr. 852; 1957-58), the preponderance of the evidence suggests that for at least some of its operating history, the operations at the Bangor MGP required the discharge of some wastewater. (Tr. 1833 (explaining that each MGP site must be examined “in context”).) 64. Generally, manufactured gas plants recycled at least some of their wastewater. (Tr. 846; 862-63.) In plants utilizing the coal gas process, recycled wastewater was used for quenching and ammonia recovery. (Tr.1954-57.) In plants utilizing the CWG process, recycled wastewater was still used for quenching. And, in plants utilizing the oil gas process, hot wastewa-ter was recycled from the tar separator. (Tr. 665-66; Exs. 378; 379; 380; 586; 587 & 588.) Only wastewater that was not recycled would need to be discharged. 65. The process by which hot coal tar is extracted from wastewater did not change significantly from the 1800s to the 1980s. Thus, it stands to reason that the amount of tar actually extracted is not significantly different and one could reasonably use tar extraction figures from the 1980s to estimate tar extraction rates using the same process at an earlier time. (Tr.1995-96.) 66. The manufacturing process at the Bangor MGP would have produced a relatively small amount of wastewater equivalent to “a household faucet cracked open a little bit” (Shifrin) or about “[0].7 gallons a minute.” (Middleton) (Tr. 856; 1971.) 67. Overall, Dr. Shifrin, an expert for the City, estimates that the total wastewa-ter discharge from the Bangor MGP during its entire operational history totaled somewhere between 7 to 70 million gallons. (Tr. 805.) 68. Utilizing a variety of sources, Dr. Shifrin has estimated that the Bangor MGP produced a total of 8 million gallons of tar during its operational history. (Tr. 798-99; Ex. 384.) However, Dr. Shifrin also believes that ninety-nine percent of the tar was ultimately separated from the wastewater leaving only approximately 80,-000 gallons of tar (one percent of the eight million gallons) entrained in the wastewa-ter. (Tr. 800; 805-809.) 69. Dr. Middleton, Citizen’s expert, broke down his estimates for both waste-water produced and the tar concentration of that wastewater based on the process that was utilized to manufacture gas at the Bangor MGP: a.For the coal gas process, Dr. Middleton assumed the concentration of tar in the wastewater discharged from the Bangor MGP was 130 milligrams per liter. Based on this estimated concentration and estimated wastewater of 34.2 million gallons, Dr. Middleton concluded that only 3,705 gallons of tar were contained in the wastewater produced by the Bangor MGP during 98 years of operation as a coal gas plant. (Tr.1959-60; 1994-96.) b. For the CWG process that was utilized at the Bangor MGP from approximately 1932 until 1948, Dr. Middleton assumed an estimated tar concentration of 268 milligrams per liter. Dr. Middleton testified that the CWG process produced between 300,000 and 1.4 million gallons of wastewater, which would have contained between 40 and 331 gallons of tarry matter. (Tr.1965-68.) c. For the oil gas process that was utilized at the Bangor MGP beginning around 1950, Dr. Middleton similarly assumed an estimated tar concentration of 268 milligrams per liter. He testified that the oil gas process produced somewhere in the range of 1.1 million to 4.3 million gallons of wastewater. Thus, Dr. Middleton estimated that this wastewa-ter contained between 264 and 1056 gallons of tar. (Tr.1971-72.) Based on the combination of these figures, Dr. Middleton opined that the total wastewater production at the Bangor MGP would have been less than 40 million gallons and this wastewater would have contained between 304 and 5,092 gallons of tar. (Tr.1972.) 70. However, these figures do not account for the recycling of wastewater at the Bangor MGP. At trial, Dr. Middleton opined that the total wastewater discharged from the Bangor MGP ranged somewhere from zero to 34.2 million gallons. The low end of this estimate assumes that the Bangor MGP recycled and reused all of its wastewater for quenching or ammonia use. (Tr.1958.) 71. The evidence presented at trial simply does not support finding that the Bangor MGP recycled 100 percent of its wastewater for its entire operational history. (Tr. 806-07,1993-94.) 72. Having considered and reviewed the opinions of both Dr. Shifrin and Dr. Middleton as well as all of the other relevant evidence presented, the preponderance of the evidence suggests that the total wastewater discharge from the Bangor MGP for all of its years of operation was at least 7 million gallons (Dr. Shifrin’s low estimate) but less than 34.2 million gallons (Dr. Middleton’s high estimate). 73. With respect to that amount of tar entrained in this discharged wastewater, the Court finds Dr. Middleton’s more detailed and substantiated estimate of the tar entrained in the discharged wastewater to be more reliable and accurate. Thus, in accordance with Dr. Middleton’s expert opinion, the Court finds that the amount of tar discharged in the Bangor MGP’s wastewater was likely no more than 5,092 gallons. 74. The Court’s decision to credit Dr. Middleton’s estimated quantities of discharged tar is further supported by Dr. Middleton’s credible testimony that it is unlikely that large quantities of tar could have actually flowed through the Old Stone Sewer since the cooler underground conditions would have caused large quantities of tar to stiffen and stick to the walls and floor of the sewer. (Tr.1975-76, 1984.) 75. In light of the fact that the Bangor MGP and all of its records were destroyed long before this litigation was commenced, it is simply not possible to reach a more specific conclusion regarding the exact amount of wastewater discharge or the concentration of tar that was present in that discharge. 76. There remains the question of whether tar entrained in the wastewater discharged from the Bangor MGP via the Old Stone Sewer would have, in fact, come to rest on the floor of Dunnett’s Cove. Dr. Middleton opined that the conditions in the Cove might not have been favorable to the settling out of tarry particles suspended in water and that perhaps such tarry particles would have been carried out of Dun-nett’s Cove with the help of the tides and the fast moving river currents. (Tr.1990-93.) Although this testimony is credible, it is also more likely true than not that the river conditions at the outfall of the Old Stone Sewer were at various time conducive to allowing tarry particles to settle out and come to rest on the floor of Dunnett’s Cove. 77. During its operational history, the Bangor MGP sold recaptured tar for profit. There is evidence of recaptured tar being sold as early as 1870. (Tr. 710, 1956.) In fact, during the time that Citizens owned and operated the Bangor MGP, tar sales were an important part of the revenue raised via operation of the Bangor MGP. (Tr. 1448-49.) 78. There is evidence that one of the entities that purchased tar produced at the Bangor MGP was the City. (Tr. 1332.) 79. Based on the preponderance of the circumstantial evidence, it appears that during its operational history the Bangor MGP discharged its tar-laden wastewater into Dunnett’s Cove via the Davis Brook Sewer. 4. The Closedown of the Bangor MGP and Remediation of the Site 80. In the mid-to-late 1960s, Maine Utility Gas suspended operations of the Bangor MGP and essentially vacated the premises. The buildings and fixtures that were left behind on the site became generally blighted. Among the problems at the blighted site, an October 1978 inspection noted “remnants of two large oil storage tanks” with one tank appearing to hold about four feet of water and the other appearing to hold oil. (Ex. 929.) 81. In 1978, the City acquired the Bangor MGP site and then oversaw the demolition and rehabilitation of the site. (Tr. 1371, 2246.) 82. During the demolition, a tank containing over 400,000 gallons of tar-entrained wastewater was unexpectedly found at the site. (Tr. 1372-73, 2250.) 83. The City’s rehabilitation of the Bangor MGP site did not remove all of the tar and tar-like material from the site. (Tr. 2251.) 84. In 1980, the Maine Department of Environmental Protection (“MDEP”) conducted a field investigation of the Bangor MGP site in connection with the City’s dismantling of the remaining fixtures and equipment. This investigation failed to locate any connection between the site and the Davis Brook Sewer. (Tr. 1048; 1374; 2135-37; Exs. 103 & 1026.) 85. The City’s clean-up of the Bangor MGP site was done pursuant to a Voluntary Remedial Action Plan (“VRAP”) approved by the MDEP. (Tr. 1832, 2279.) Through its VRAP program, MDEP allows applicants to work cooperatively with MDEP to cleanup contaminated sites on a voluntary basis in exchange for future protection from MDEP enforcement actions. (Tr. 106-07.) See also 38 M.R.S.A. § 343-E. 86. In or around the late 1980s or early 1990s, the City hired a contractor to install a parking lot with catch basins at the Bangor MGP site. (Tr. 2129.) 87. During this parking lot installation, the contractor encountered two areas that appeared contaminated with liquid tar-like materials. In one location, which was supposed to be the location of a catch basin, the contractor encountered tar-like material that appeared to be over 4 feet deep. In the other location, the tar-like material appeared to ooze out of the ground. Although the City was notified of this discovery, no additional cleanup of these observed tar-like materials was done. (Tr. 2130-32; Ex. 1125.) 88. By letter dated August 18, 1995, the EPA announced that it would not list the Bangor MGP on the National Priorities List of sites in need of environmental cleanup. The EPA reached this conclusion after consulting with MDEP regarding the VRAP for the site. Based in part on the representation that residual contaminants at the Bangor MGP site were not affecting drinking water or being actively discharged into the Penobscot River, the EPA concluded that “residual contaminants present at the [Bangor MGP] site do not pose a significant threat to human health or the environment.” (Ex. 779.) C. The History and Operation of the Davis Brook Sewer & the Old Stone Sewer 89. Prior to the construction of the Davis Brook Sewer, a stream known as Davis Brook flowed along the present day course of the Davis Brook Sewer. (Tr. 1386-87.) 90. In the early 1800s, residents and businesses likely used Davis Brook as an open sewer. (Tr. 1386-87.) 91. Davis Brook ran through the site on which the Bangor MGP was constructed. (Ex. 54.) 92. In June 1852, the City of Bangor gave conditional approval to the Bangor MGP requiring, in relevant part, that the Bangor Gas Light Company “construct and maintain and use a covered drain, extending from their works to the Penob-scot River to below [the] low water mark, of sufficient capacity to carry off all the residuum of filth of said works.” (Ex. 51; Stipulation # 30 (Docket # 559).) 93. Notwithstanding this requirement, in 1860, the Bangor Gas Light Company petitioned the City to construct a public sewer from the vicinity of Bangor Gas Works to the Penobscot River. On July 9, 1860, the City approved the petition deeming it “necessary for public convenience and health.” (Ex. 62 at BGR 5830.) 94. Thereafter, the City contracted for the construction of such a public sewer, which came to be known as the Davis Brook Sewer. (Stipulation # 31 (Docket # 559); Ex. 54.) The lower portion of this sewer line leading into the Penobscot River is also known as “the Old Stone Sewer.” 95. Although the ordinances of the City from the late 1800s contemplated that anyone utilizing a public drain or municipal sewer would be required to pay an assessment (Exs. 1090 & 1093), there is at least one city record suggesting that the Bangor Gas Light Company was not required to pay such an assessment in the late 1800s since the record indicated that Bangor Gas Light Company had “no sewer.” (Ex. 775.) 96. In 1888, the City made some extensive repairs to the Davis Brook Sewer at the Bangor MGP site. The Bangor Gas Company paid half the cost of this repair work. (Ex. 72 at BGRG 0000630.) 97. In a letter dated February 21, 1901, the then-President of the Bangor Gas Light Company complained to the City Council regarding two separate incidents in which the sewer had burst, resulting in water damage to the Bangor MGP property. In this letter, Bangor Gas Light Company claimed that the City had “overtaxed” its “private drain” by connecting “a large territory” of the City to the drain and asked that the City make other arrangements for this sewage rather than “turning it into [the Bangor Gas Light Company’s] private drain.” (Ex. 77 at BGR0000536.) 98. In 1929, the portion of the Davis Brook Sewer that passed beneath the site of the Bangor MGP was relocated to accommodate expansion of the MGP. Bangor Gas Light Company paid a portion of the costs for this relocation. (Stipulation # s 32 & 33 (Docket # 559).) 99. From the mid-1800s into the 1960s, the Davis Brook Sewer, like many other sewers, emptied without treatment into the Penobscot River. (Stipulation # 34 (Docket # 559); Tr. 1349.) 100. Over time, the City connected street drains and additional sewer lines, including the Sanford Brook sewer, into the Old Stone Sewer. Thus, the Old Stone Sewer was used to carry wastewater generated in a portion of the City. (Stipulation # 38 (Docket # 559); Tr. 1342; 1344-49; Ex. 485.) 101. At its height, the Old Stone Sewer serviced a drainage area of approximately 300 acres. (Tr. 1344-45, 1630; Ex. 418D.) 102. Above the area of the Bangor MGP, the Davis Brook Sewer was generally constructed of actual pipes or brick and mortar. However, in the area between Main Street and the outlet into Dunnett’s Cove, the floor of the Old Stone Sewer appears to be the natural stream bed of Davis Brook with additional rocks added to the sides and granite slabs on top to create a stone sewer “pipe.” (Tr. 1387-88; 1412; Ex. 485.) 103. In 1959 and 1960, the City received two complaint letters from a local attorney, Edward Conquest, regarding the Davis Brook Sewer and Old Stone Sewer. (Exs. 918 & 919.) In these letters, Mr. Conquest complained that these sewers were overtaxed and not being adequately maintained. Both letters noted separate incidents in which the sewers backed up in storms causing flooding and damage to area homes and buildings. (Id.) 104. By the 1960s, the City, like many other communities, began to recognize that sewer systems that simply collected and then discharged that untreated wastewater into nearby bodies of water produced “atrocious odors” and significant adverse impacts on the environment. (Tr. 1357-58; Exs. 1314-15.) The City began revamping its sewer system to address these problems. 105. In 1962, the City redirected a portion of the Davis Brook Sewer thereby terminating the flow in an upper portion of the Old Stone Sewer. (Tr. 1354-55, 1632, 1636-38; Ex. 415D.) Thus, there is a section of the Old Stone Sewer that has not received any flow since 1962. 106. In 1967, as part of the City’s plans to end the direct discharge of sewage into the Penobscot River, the City constructed a diversion weir and interceptor pipe in the Old Stone Sewer above the high tide mark. As a result of this project, waste-water was directed to the City’s newly constructed wastewater treatment plant. (Stipulation # s 35 & 43 (Docket # s 559 & 564); Tr. 872,1324,1346-49.) 107. As a result of this diversion weir construction, wastewater no longer flowed down the section of the Old Stone Sewer that extended from approximately Main Street to Dunnett’s Cove, except for limited periods of high flow conditions. (Stipulation # s 36 & 43 (Docket # s 559 & 564); Tr. 1348-49.) 108. In 1992, the City made some additional improvements to the diversion weir. (Tr. 1359-60.) 109. In or around 1999, the City constructed the combined sewer overflow (“CSO”) structure. (Tr. 1638, 2271; Ex. 1314.) 110. Today, the outfall of the Old Stone Sewer appears quiet (since there is no longer any discharge) and the immediate outfall appears covered with fairly clean sediment. (Tr. 1518.) 111. Within the Old Stone Sewer there remains an area of tidal influence that stretches from the outfall up approximately 600 feet. (Tr. 1422-23; Exs. 415D & 485.) This area continues to receive inflow from the Penobscot River during periods of high tide. 112. Today, above the area of tidal influence there is no visible tar in the Old Stone Sewer. (Tr. 1405, 1419, 1423-24, 1633-34.) 113. Within the Old Stone Sewer’s area of tidal influence there are varying degrees of visible tar-like material. (Tr. 1424-46; Ex. 485.) It is likely that some of this material is the result of tar blebs being carried from the Cove into the Old Stone Sewer during periods of high tide. (Tr. 211; 345-62.) 114. Some of the sampling done in the Old Stone Sewer detected elevated levels of PAHs, including some very high levels of PAHs (e.g., SUB OSS 4 (14,700 ppm), HAOSS-6A (11,100 ppm), HAOSS-270 (14,000 ppm)). (Ex. 506.) 115. Evidence of tar and elevated PAH levels was found beneath the floor of the Sewer above the area of tidal influence. (Tr. 367-374; Ex. 373.) This recent sampling from under the cobbles of the Old Stone Sewer detected both coal tar and petroleum tar. (Tr. 1419; Exs. 368, 390, 506 & 530.) 116. At trial, Citizens attempted to prove that the tar found beneath the cobbles of the Old Stone Sewer was the result of tar being used to cement together the cobblestone floor of the Old Stone Sewer. (Tr. 211-12; Ex. 772.) Although there is evidence that coal tar was, in fact, used as a pitch filler during paving operations in the early 1900s, there is no evidence that coal tar was, in fact, used as a pitch filler in the construction of the Old Stone Sewer. (Id.) Moreover, there was no evidence that petroleum tar was used as pitch filler generally or that it was specifically used in the construction or maintenance of the walls and floor of the Old Stone Sewer. 117. Thus, to the extent that samples taken from above the area of tidal influence within the Old Stone Sewer were ultimately found to contain petroleum tar, the most likely explanation for this petroleum tar is that it was contained in materials that were discharged into the Old Stone Sewer. (Tr. 1001, 2153-55; Exs. 506 & 507.) 118. Similarly, on the record presented, it is more likely that coal tar found in samples taken from the Old Stone Sewer is the result of discharges into the Sewer rather than materials used to construct the sewer. 119. To the extent tar was found beneath the cobbles of the Old Stone Sewer, it is certainly possible and even probable that some of this tar came to rest below the Old Stone Sewer as a result of some other preferential pathway. Despite this evidence of other preferential pathways that might account for the tar beneath the floor of the Old Stone Sewer, the preponderance of the evidence also supports finding that tar was discharged into and traveled through the Old Stone Sewer. (Tr. 1419, 2229-30.) 120. Although the City has sought to disavow its ownership of the Davis Brook Sewer in the context of this trial, it is clear that the City is the current owner of the Davis Brook Sewer as well as the now defunct Old Stone Sewer. (Tr. 1324; 1380-82,1395.) 121. Moreover, having considered all of the evidence offered at trial, the Court finds that the City owned relevant portions of the Davis Brook Sewer and Old Stone Sewer during the time that the Bangor MGP discharged tar-laden wastewater into the sewer. (Tr. 1345; Ex. 879,1090.) 122. In fact, via its various repairs and improvements to the Sewer, the City undoubtedly arranged for the continued discharge of tar-laden wastewater and assisted in the discharge of this tar-laden wastewater into Dunnett’s Cove. (Tr. 1324.) D. The Environmental Investigation of the Dunnett’s Cove Contamination & the Procedural History of this Litigation 123. In addition to being subjected to seasonal changes, the area of the Penob-scot River known as Dunnett’s Cove has also been affected by man-made changes over the last 150 years, including dredging as well as the building and subsequent breaching of upstream dams. (Tr. 1866-1868.) 124. A 1980 MDEP investigation documented a “pool of coal tar found in the river” but concluded that the contamination was “separate from [the Bangor MGP] site” because MDEP could find “few links between the site and the river.” At that time, the MDEP appeared to suggest that there might have been a connection between the Bangor MGP and the River via a sewer line but they noted that “[t]he sewer line across the street possessed only a low level # 2 fuel contamination common to sewer systems.” (Tr. 2141; Ex. 899.) 125. A 1980 dive survey of the Dun-nett’s Cove area observed “hardened ... tar like substance” on the river bottom that “extended about thirty yards out from shore at the low tide mark.” (Ex. 1098; Tr. 2142.) The divers also observed “an area of what appeared to be more recent material” that “was more viscous and had a brighter, glassier shine.” (Id.) At that time, the divers were unable to locate a source of this contamination, which was reportedly causing “pancake size sheens.” (Id.) 126. In 1993, the MDEP once again began investigating possible tar contamination in Dunnett’s Cove. This investigation included sampling of sediments in the Cove. (Tr. 1038-39.) 127. In 1996, as a result of its investigation of tar tanks once located on the Maine Central Railroad, MDEP concluded that there was no active migration of coal tar from the railroad property into the Penobscot River and that the “the coal tar present in the river is from direct historical placement, possibly through the use of pipelines present along the embankment of the river.” (Ex. 1041 at DEP0004.) 128. Although the MDEP’s investigation of the Cove contamination proceeded slowly, the City was interested in expediting the cleanup of Dunnett’s Cove as part of its larger plan to redevelop the Bangor waterfront. The City’s plans included potentially building an amphitheater on the shore of Dunnett’s Cove. (Tr. 1364, 1071-72; Exs. 641, 617 & 900.) 129. In June 1999, the City hired RMT, Inc. (“RMT”) to investigate whether the Bangor MGP was the source of the tar contamination in Dunnett’s Cove. (Tr. 46-48; Ex. 670.) 130. The City hired RMT in conjunction with its decision to retain Attorney Laseter, who, in the Fall of 1998, had approached the City about the possibility of bringing claims against previous owners and operators of the Bangor MGP. (Tr. 435-40; Tr. 2298-99.) 131. Based on the evidence presented at trial, it is clear that since the City’s investigation of the Dunnett’s Cove contamination began in 1999, this investigation has focused on tying the Cove contamination to the Bangor MGP and, as a result, did not adequately explore and consider other sources. (Tr. 47, 121-23, 451-58, 471, 502-09, 607-08, 1134-35, 1137-38, 1642-43; Exs. 1256,1293 & 1336.) 132. In his first visit to Dunnett’s Cove in June 1999, Eugene McLinn, a hydro-geologist from RMT and the City’s lead investigator, saw multiple tar deposits in the Cove area and also noted that there appeared to be multiple drains and outfalls along the shore of the Dunnett’s Cove. Nonetheless, he did not undertake to test each of these outfalls. (Tr. 440^45; Ex. 1285.) 133. In 1999, RMT did conduct initial sediment sampling in the Old Stone Sewer. This initial testing yielded PAH levels that were consistent with urban background. (Tr. 462-63, 489,1641) 134. In late August or early September 1999, Attorney Laseter telephoned L. Russell Mitten, an attorney for Citizens, and told Attorney Mitten that he represented the City and that the City had claims against Citizens for its earlier operation of the Bangor MGP. At the time, Mitten was not even aware that Citizens had ever had any operations in Maine. (Tr. 2352-54.) 135. The City demolished the Bangor MGP site almost twenty years prior to Citizens receiving any notice of the City’s claims. (Tr. 2352-53.) 136. In 2000, the City and RMT asked the MDEP to provide comments on a proposed sampling plan that it intended to use to characterize the size and shape of the tar contamination in Dunnett’s Cove. (Tr. 1043-44.) 137. By July 2001, RMT had first delineated the extent of the Dunnett’s Cove tar contamination as a large “tar plume” that began at the outfall of the Old Stone Sewer and gradually extended down the Cove. (Tr. 177, 1533-34; Ex. 371 Fig. 5.) 138. In August 2001, the City entered into a Memorandum of Agreement (“MOA”) with the MDEP under which the MDEP agreed to reimburse the City for fifty percent of the costs incurred in the continuing investigation of the Dunnett’s Cove contamination with the State paying up to $250,000. (Stipulation # 40 (Docket # 559); Ex. 336.) 139. The MOA was amended in 2003. Pursuant to this amendment, the MDEP agreed to provide an additional $70,000 of funding for the investigation. (Stipulation # 41 (Docket # 559); Ex. 337.) 140. The MOA under which the State and City jointly funded RMT’s investigation of the Dunnett’s Cove site did not comply with the usual MDEP procedures for subcontracting an environmental investigation. (Exs. 612 & 613; Tr. 1066-67.) Under this unique funding mechanism, RMT essentially became the MDEP’s lead investigator of the Dunnett’s Cove site although RMT had been selected by the City and the City planned to use RMT as its main expert witness in this case. (Tr. 478,1066.) 141. On November 22, 2002, the City commenced the present case against Citizens. (See generally Compl. (Docket #D.) 142. In 2003, Citizens approached MDEP and asked that its experts, Haley & Aldrich, be allowed to assist RMT with the MDEP investigation of the Dunnett’s Cove site. Although Citizens offered to pay for the assistance provided by Haley & Aldrich, MDEP ultimately decided not to retain Haley & Aldrich and allowed RMT to continue the State’s investigation of the Dunnett’s Cove site alone. (Tr. 1545-47; 2355-56; Ex. 650.) 143. It is clear that the City exerted pressure on MDEP in order to maintain funding and obtain favorable MDEP action on the Dunnett’s Cove site, including having the site designated pursuant to Maine’s Uncontrolled Hazardous Substance Site Law. (Exs. 637, 656, 658, 664, 665; Tr. 1076-77.) 144. MDEP issued a seven page document, dated March 3, 2004, which designated the tar deposit in Dunnett’s Cove as an Uncontrolled Hazardous Substance Site pursuant to Maine’s Uncontrolled Hazardous Substance Site Law, 38 M.R.S.A. § 1364(4). (the “Designation”) (Ex. 348; Tr. 1081.) 145. The Designation substantially relies upon RMT’s investigation of the Dun-nett’s Cove site and is a result of the City’s collaboration with the MDEP. (Exs. 612, 613, 625, 627, 629, 632, 634, 635, 645, 646, 656; 1295). 146. It is unlikely that the MDEP would have issued the Designation when it did absent the City’s efforts to expedite MDEP action on the Dunnett’s Cove site. (Tr.1925-30; Exs. 658, 664.) 147. In conducting its own field investigation during discovery, Citizens’ experts, Haley & Aldrich, encountered various roadblocks and a general lack of cooperation from the City and its lead investigators, RMT. These roadblocks included the City requiring that Haley & Aldrich field investigators sign liability releases before being allowed to enter the Davis Brook Sewer. (Tr. 1395, 1548-50.) There is no evidence that the City’s experts were required to sign similar releases in connection with their field work. 148. In 2004, the City and Citizens agreed to jointly hire an expert, Blasland, Bouck & Lee, Inc. (“BBL”), to determine what would be involved in remedying the hazard posed by the tar deposit and high concentrations of PAHs found in Dunnett’s Cove. (Nov. 2, 2004 Joint Mem. at 1-2 (Docket # 417).) 149. This joint effort resulted in the parties’ joint submission of a final feasibility study to MDEP, which the MDEP conditionally approved on August 17, 2005. (Stipulation # 42 (Docket # 559); Tr. 1066; Aug. 18, 2005 Joint Status Report (Docket # 509).) 150. The City has incurred approximately $1,000,000 in documented costs during the course of its investigation of the tar contamination in Dunnett’s Cove. (Ex. 128.) 151. Citizens has incurred a total of $1,331,185.36 in documented costs during the course of its investigation of the tar contamination in Dunnett’s Cove. This investigation was undertaken in connection with the discovery done by Citizens during the course of this case. (Ex. 996.) 152. As of July 9, 2005, Blasland, Bouck & Lee, Inc. (“BBL”) has also jointly billed Citizens and the City for a total of $511,127.11. The parties’ work with BBL culminated in the submission of the Joint Final Feasibility Study to MDEP in July 2005. Per an agreement between the parties, each side has paid for half of BBL’s costs. (Tr. 2381-82; Ex. 1024A.) E. The Current Status of Dunnett’s Cove 153. Dunnett’s Cove is a ten acre area within the Penobscot River. The Penobscot River is a dynamic river with a large tidal range. (Tr. 498,1866.) 154. Within the area of Dunnett’s Cove the average tidal fluctuation is approximately 13 feet. (Tr. 526, 1623.) There is generally a strong downstream flow during the ebb tide and a relatively little upstream flow during peak flood tide. (Ex. 500.) 155. Within Dunnett’s Cove, there is a shallow area along the shore that is quiescent, meaning it is not subject to the flow velocity generally found in the main channel of the Penobscot River. However, outside this shallow area, most of Dunnett’s Cove actually has a river flow velocity that is similar to that found in the main channel. (Tr. 1862,1913.) 156. The submerged portions of Dun-nett’s Cove that comprise the “facility” at issue in this case are owned by the State of Maine. (Stipulation # 4 (Docket # 559); Ex. 348 at ¶ 5.) See 42 U.S.C. § 9601(9); 12 M.R.S.A. §§ 1801(9) & 1862. The inter-tidal zone portion of Dunnett’s Cove that is also part of the facility in this case is owned by the City. See 12 M.R.S.A. § 573. 157. Some of the sediments in Dun-nett’s Cove contain elevated levels of PAHs. (Stipulation # 1 (Docket # 559).) At least some of these PAHs are from tar. (Stipulation # 2 (Docket # 559).) 158. Samples taken from Dunnett’s Cove have been identified as containing coal tar, petroleum tar and, in some cases, both. Asphalt has also been found in some samples. (See, e.g., Ex. A to Docket # 631, Ex. 506.) 159. Since the 1960s, there have been anecdotal reports of tar residue appearing as both sheens and blebs in Dunnett’s Cove. (Tr. 640, 1375; Ex. 275 at HAR16788; Ex. 1041 at DEP00003; Ex. 923.) 160. The most active areas of sheening and blebbing are located in the northern end of Dunnett’s Cove near the outfall of the Old Stone Sewer. (Tr. 386, 1511-12, 1792.) On the floor of the Cove below the areas on the surface where sheening and blebbing have been regularly observed, there is tar that has a more oil-like appearance. This non-hardened, oil-like tar covers an area that is less than a half acre. (Tr. 1792-93.) 1. The Northern Portion of Dunnett’s Cove (aka the Bulkhead Area) 161. In the northern end of Dunnett’s Cove, a recently-constructed steel bulkhead intersects with a granite bulkhead. (Tr. 1366; Ex. 444.) 162. This granite bulkhead was at one time the location of the Maine Central Railroad wharf. (Tr. 1505.) 163. The investigations conducted in conjunction with this case have documented significant amounts of tar both on and in-between the granite bulkhead stones. (Tr. 1505-13; 446-49; Ex. 444.) Sampling of the tar found in this location was completed and the samples typed as petroleum tar. (Tr. 1507,1509,1512-14.) 164. The steel bulkhead that is now found in the northern end of Dunnett’s Cove was constructed in 2001. This steel bulkhead was erected in front of a preexisting timber bulkhead. (Tr. 596, 600; Exs. 444, 900.) 165. The timber bulkhead had essentially failed by 1999. The timbers were highly weathered and there had been subsistence of the soils behind the bulkhead. In fact, for some period of time prior to the completion of the steel bulkhead, it appears that the soils behind the timber bulkhead were sloughing off into the River due to the effect of both the general flow of the river and the ebb and flow of the tides. (Tr. 594-95, 599, 1582; Exs. 689 at BGRS0000151 & 900.) 166. Multiple investigations have documented the existence of tar-like materials in the soils behind this area of the bulkhead. (Exs. 502, 689 & 900.) 167. In fact, two borings that Haley & Aldrich were allowed to install in the area behind the bulkhead documented coal and coal tar in the soils. (Tr. 1597-98; Exs. 506 (HATTN-1 & HATTN 2).) However, these same samples had relatively low levels of PAHs. (Ex. 506.) 168. During a 2005 excavation of an area less than ten feet behind the steel bulkhead, the contractor encountered a layer of material that was later determined to be coal tar. Sampling of this layer detected some of the very highest levels of PAHs found during any of the testing done in connection with this case, including one sample with a PAH concentration of over 200,000 parts per million. (Tr. 596-600, 1598-1600, 2061-62; Exs. 502, 991D.) 169. In this northern portion of the Cove, there is also evidence of tar contamination on the banks of the Cove with some documented “tar flows” that begin above the high tide mark. (Tr. 1515-16.) 170. Within the northern portion of Dunnett’s Cove, one can find examples of almost every kind of tar deposit, including oil-like viscous tar, as well as hard tar deposits that are both flat and raised in the shape of “Hershey’s Kisses.” (Tr. 1564-67; 1569-70.) One can also see areas that do not appear to be impacted by tar contamination. (Tr. 1568 & 1570.) 2. The Outfall of the Old Stone Sewer 171. In many, if not most, of the sediment cores taken from the Old Stone Sewer outfall area within Dunnett’s Cove, there is a pattern of petroleum tar layered over coal tar. (Tr. 321, 2215-16; Ex. 372.) However, there are sediment cores that do not follow this pattern. (Exs. 372 (e.g., HAC-106, HAC-110, HAC-111), 530-D, 506, 507; Tr.2050-51.) 172. Coal tar was identified as the bottom most tar type in almost ninety percent of the sediment cores taken from the area surrounding the Old Stone Sewer outfall. (Tr. 2215-16; Ex. 372.) 173. Based on the layering found in multiple sediment cores and the principle of super position, it is more likely than not that coal tar was deposited on the floor of Dunnett’s Cove near the sewer outfall followed by a deposit of petroleum tar. (Tr. 308.) 174. A 2003 field investigation of Dun-nett’s Cove documented both petroleum tar and asphalt on the shore of Dunnett’s Cove above the high tide mark. (Tr. 1519-23,1668-72; Ex. 506.) 175. Of approximately twenty samples sent for chemical testing by the City, eight to ten samples tested negative for NAPLs. Twelve of the samples tested positive for NAPLs and were found to have high levels of PAHs. (Ex. 389, slide 2; Tr. 991-92.) 176. Sampling of the sediments collected from near the outfall of the Old Stone Sewer contained both coal tar and petroleum tar, but not asphalt. (Tr. 83; 1672-73; 2178.) 177. The tar contamination is thickest near the outfall of the Sewer as well as more continuous as compared to the contamination found downstream in the southern end of Dunnett’s Cove. (Tr. 147, 173, 190, 296.) 178. The tar in this area is not hardened as it is in some other areas of the Cove. (Tr. 492.) 3. The Southern Portion of Dunnett’s Cove 179. Haley & Aldrich documented four deposits of tar-like material that appeared to be flowing down the riverbanks on Dun-nett’s Cove in the southern area of the Cove. These flows were located in the intertidal zone and upon further observation exhibited signs of “recent” flow. (Tr. 1525-26.) 180. Near Barrett’s Paving, there are isolated puddles of tar on the floor of the southern portion of Dunnett’s Cove. (Tr. 383-85, 401, 492.) 181. Divers who observed the tar in this area described puddles of tar that varied from a foot to a couple of feet in diameter and that rose up from the floor of the Cove, in some cases approximately two feet tall. (Tr. 1559-60.) 182. A video of the dive survey in this area showed hardened tar in “Hershey’s Kiss” shapes. (Ex. 413-B; Tr. 1558-60.) Based on the shape and consistency of the “Hershey’s Kiss” deposits, it appears that the material that makes up these deposits was released on the surface and then settled to the bottom. (Tr. 1569-70, 1645.) 183. Because of the hydrodynamics of the Penobscot River generally and Dun-nett’s Cove specifically, it is unlikely that tar contamination that originated in the southern end of the Cove could have moved up into the northern end of the Cove. (Tr. 401; 2207.) 4. The Extent of the Tar Contamination in Dunnett’s Cove 184. According to Dr. Shifrin, one of the City’s trial experts, there are approximately 60,000 to 80,000 gallons of tar entrained in the sediments of Dunnett’s Cove. (Tr. 799 & Ex. 382.) 185. In 2000, Eugene McLinn, the City’s lead investigator, estimated that the amount of impacted sediment in Dunnett’s Cove was ranged from “120 to 160,000 cubic yards.” (Tr. 169.) 186. Based on the investigation undertaken by Haley and Aldrich, Wanda Ratliff, Citizen’s expert, concluded that only a quarter to a third of the sediments in Dunnett’s Cove contain tar or tar-like materials. According to Ratliff, the other two-thirds to three-quarters of the Cove are “clean.” (Tr. 1821-22; see also Tr. 1573.) 187. To the extent that the City has sought to delineate the tar contamination as a plume that begins at the outfall of the Old Stone Sewer and extends down the length of the Cove, the evidence submitted at trial does not support finding that the tar contamination1 falls exclusively within this delineated plume. (Tr. 1855, 1909; Ex. 3 Fig. 4, Exs. 371 & 530.) 188. Rather, there is evidence of tar contamination in Dunnett’s Cove that falls outside the plume. (Tr. 383-85, 1536-41, 1577-78; Exs. 405D & 506 (e.g., HARB-21, CB-175, BP-S3, BP-S4, BP-S5, BP-87, BP-S9); see also Ex. A to Docket # 631.) 189. Likewise, some areas within the delineated plume are not contaminated. (Tr. 1532-35,1821-22.) In other words, on the current record, it appears that there are areas within the ten acre delineated plume that are not releasing or threatening to release PAHs. Within the ten acre delineated plume, there are some areas that do not appear to pose any substantial and imminent risk to health or the environment. 190. At trial, Mr. McLinn, the City’s expert and source of the ten acre tar plume, acknowledged that someone “could have interpreted the data [that he used to draw the tar plume] a different way.” (Tr. 475.) In fact, Citizens’ designated expert on hydrodynamics, Dr. Swanson, testified that he did interpret the data differently. (Tr. 1854-59, 1909; Exs. 497 & 498D.) 191. There is a reasonable potential for harm to people if they were to come into contact with substantial amounts of the tar contamination found in Dunnett’ Cove. However, the only real potential for human contact with the tar contamination arises in the intertidal zone and from the bleb-bing and sheening of tar. (Tr. 1811-16.) 192. On the record presented, the possibility of any human contact and the risk of endangerment to humans or the environment is remote and de minimus in those areas of the Cove that have hardened tar deposits, which are constantly covered by water or ice and are not subject to blebbing or sheening. (Tr. 1542-43; 1818-19.) G. The Source of the Contamination in Dunnett’s Cove 193. The primary source of the hazardous levels of PAHs in Dunnett’s Cove is tar. (Stipulations # s 1-3, 28 (Docket # 559).) 194. Chemical analysis of various samples from Dunnett’s Cove tells us that there are clearly elevated levels of PAHs in parts of the Cove and that coal tar and petroleum tar are the primary materials causing these elevated PAH levels. 195. There is no one source that can explain the various types, concentrations and shapes of the PAH contamination in Dunnett’s Cove. (Tr. 1854-55, 1859-60, 1878; Ex. 506.) Rather, there are multiple potential sources for these materials. (Tr. 1024-25.) In the sections that follow, the Court makes findings related to the potential sources that were brought to the Court’s attention via the evidence presented at the first phase trial. 1. The Bangor MGP 196. Tar was a byproduct of the Bangor MGP throughout its operating life. (Stipulation # 16 (Docket # 559).) 197. Prior to 1860, it was common for many MGP plants to simply discard tar via discharge into a nearby body of water. Even after that date, some small plants, especially ones utilizing the CWG process, discharged tarry wastewater because there was too little tar to economically justify attempts at recovery. (Tr. 2220.) 198. By the early 1900s, it was generally known that wastewater from manufactured gas plants had “an oily and tarry nature” and also had a “tendency ... to deposit on the shore or banks of a stream in the form of a shiny coating” if it was simply discharged. (Ex. 75 MID00002.) However, it was also thought that this problem could be solved or at least limited via the use of various tar separation techniques. (Id.; see also Ex. 81 at MID 00648-51.) 199. The distance between the Bangor MGP and the outfall of the Old Stone Sewer is approximately 1000 feet. (Tr. 1979.) 200. The layering of coal tar beneath petroleum tar, which was found in most of the sediment cores taken in the area of the outfall of the Old Stone Sewer, is consistent with the historical operations of the Bangor MGP; namely, the Bangor MGP produced coal tar as a byproduct from approximately 1852 until 1949 and produced petroleum tar as a by-product from approximately 1932 until 1963. (Tr. 308.) 201. However, this layering is consistent not only with the type of tar that would have been found in the wastewater discharge of the Bangor MGP, but also with the type of tar that the Bangor MGP might have sold to others for use in the Bangor area. Nonetheless, there is no evidence of other regular historical discharges that could entirely explain the layering of petroleum tar over coal tar in the quantities found at the outfall of the Old Stone Sewer. 202. There was no evidence to support a finding that the Bangor MGP engaged in either intentional or unintentional episodic releases of concentrated or pure tar into Dunnett’s Cove via the Old Stone Sewer or any other means. (Tr. 1838.) 203. In fact, the credible evidence suggests that if heavy concentrations of liquid tar had been discharged into the Sewer, these discharges would have cooled, stiffened and stuck to the walls and floor of the Old Stone Sewer. (Tr.1975.) 204. However, as the Court has already found, there is no visible tar in the areas of the Old Stone Sewer that are above the area of tidal influence. (Tr.