Full opinion text
POOLER, District Judge. TABLE OF CONTENTS Introduction.333 Procedural Background.334 Findings of Fact.334 I.Layout of the Site and History of Its Ownership-334 II.Subsurface Conditions. ...335 III.History of Solvent Loss During Norton’s Stewardship ...336 A. Norton’s Solvent Usage .336 B. Solvent Related Complaints and Responses.336 IV. Nashua’s Purchase of the Plant.338 V. Norton’s Solvent Usage After the Sale.339 VI. Nashua’s Tenure.339 A. Solvent Usage.339 B. Nashua’s Leaks and Spills.340 VII.The Investigative Process.,... 341 A. The B-l Boring. 341 B. EPA Notification.341 C. The Limited Cooperative Investigation.342 D. The Dunn-Rust Investigation.342 VIII. Causation.345 A. Nashua’s Contributions to Site Contamination.345 B. Norton’s Contribution to Site Contamination.346 1. The Bear-Tex Premises.346 2. The 1960s Leaks.346 Application of the Law to the Facts.350 I. CERCLA.350 A. Section 107 Claims.350 B. Section 113(f)(1) Claims .351 II. RCRA Claims.355 A. Propriety of a RCRA Claim.356 B. Imminent Danger.356 C. Cost Recovery Under RCRA.357 D. Injunctive Relief.358 E. Attorney’s Fees.359 Conclusions of Law.359 Appendix I- — P-245: Sample Locations and Areas of Potential Releases.I Appendix II — P-246: Ground Water Analytical Results.II Appendix III — P-247: Sewer Analytical Results.Ill Appendix IV- — P-248: Soil and Soil Gas Analytical Results.IV Appendix V — P-250: Map of the Site and its Neighbors .V Appendix VI— Frequently Used Abbreviations.VI DECISION AFTER TRIAL INTRODUCTION Plaintiff Nashua Corporation (“Nashua”) owns and operates a pressure-sensitive tape manufacturing facility in Watervliet, New York. From the 1930s until 1974, defendant Norton Company (“Norton”) owned and operated the tape-manufacturing facility. In the mid 1960s, Norton’s underground solvent transfer lines leaked, causing massive toluene and tolusol contamination. After discovering the spill, Norton replaced the underground lines and made clean-up efforts. However, pollution from solvents of the type Norton used persists in the soil and groundwater under the Nashua plant. Nashua claims that the pollution results directly from Norton’s leaking pipelines and its later sloppy housekeeping in a portion of the property it leased back from Nashua after the sale (the “Bear-Tex Premises”). Norton argues that (1) the current contamination could not have resulted from its releases; (2) various spills and emissions during Nashua’s ownership of the Plant caused the pollution; and (3) even assuming Norton caused some or all of the contamination, it is not liable for Nashua’s response costs because they are unreasonable and do not comply with governing law. After weighing the evidence submitted at trial and considering the parties’ post-trial submissions, I conclude — for reasons discussed in detail below — that Norton must bear 90% of Nashua’s response and clean-up costs. PROCEDURAL BACKGROUND On August 31, 1989, the United States Environmental Protection Agency (“EPA”) issued notice letters to both Nashua and Norton regarding their potential liability under the Comprehensive Environmental Response, Compensation and Liability Act, 42 U.S.C. § 9601 et. seq. (“CERCLA”). P-23. After initial cooperative investigation and negotiation, Nashua and Norton disagreed on the appropriate division of clean-up costs, causing Nashua to file this lawsuit on December 14, 1990. Nashua sought recovery pursuant to CERCLA and made a New York common law nuisance claim. See Dkt. No. 1. In April, 1994, this court (McCurn, J) granted partial summary judgment rejecting Norton’s claim that Nashua assumed liability for all the claims asserted in its complaint when it purchased the Site. See Nashua Corp. v. Norton Co., 1994 WL 144251 (N.D.N.Y. Apr.18, 1994). In February 1995, Nashua amended its complaint to add a citizen suit claim under the Resource Conservation and Recovery Act, 42 U.S.C. § 6901 et. seq. (“RCRA”). See Dkt. No. 108. On June 19, 1995, with trial scheduled to start on September 12, 1995, Norton moved for partial summary judgment dismissing Nashua’s claim for diminished property value based on nuisance. I directed the parties to proceed to trial on the liability issues and informed them that I would issue a decision on the permissibility of diminished value damages prior to any diminished value damages phase. The CERCLA/RCRA phase of the trial took place October 10 through October 25, 1995; December 5 through December 6, 1995; December 8, 1995, through December 15, 1995; February 12 through February 14, 1996; March 4 through March 6, 1996; and May 21 through May 22, 1996. On April 15, 1997, I issued a memorandum-decision and order dismissing Nashua’s private nuisance claims as they related to spills at the Nashua Plant but allowing Nashua to proceed on public nuisance claims and private nuisance claims stemming from alleged polluting activities by Norton at the Bear-Tex Premises adjacent to the Nashua operation. See Nashua Corp. v. Norton Co., 1997 WL 204904 (N.D.N.Y. Apr.15, 1997). The parties made their final post-trial submissions on August 5, 1997. My findings of fact, analysis, and conclusions of law follow. Many of the findings of fact are based on stipulation or largely uncontroverted evidence. Where a serious credibility dispute exists, I will discuss my reasons for crediting the evidence offered by one party over that offered by the other either immediately or in my discussion of the expert opinions. FINDINGS OF FACT I. Layout of the Site and History of Its Ownership From the 1930s to 1974, Norton owned and operated two manufacturing facilities, known as Plant 1 and Plant 2 in Water-vliet. St. A-l; see also P-235. In Plant 2, the more western of the two, Norton manufactured coated abrasives such as sandpaper. Norton manufactured pressure sensitive adhesive tape in Plant 1. St. A-2, A-8. The parties refer to the interconnected buildings of Plant 1 and the adjacent property as the “Site.” St. A-5. In 1974, Nashua purchased Norton’s tape manufacturing division including interconnected buildings 56, 56A, 58, 59, 60 and 61 in Plant 1 and adjacent land. St. A5, A7. Nashua then sold Building 56, the most northwestern of its buildings to Norton, which leased it to Donald Stone. St. A-7, P235. Around the same time, Nashua leased the northern half of Building 61, which occupies most of the northern portion of the Nashua plant to Norton. St. A-8. Norton used its portion of Building 61 for its Bear-Tex production line. St. A-8. Norton discontinued the Bear-Tex operation on December 20, 1989, and removed all its equipment from the site by March 30,1990. St. A-12, A-13. Two tank farms are situated to the north of Building 61 and near the north property line. St. A-14, P-245, Appendix 1. Tank Farm No. 1, the eastern of the two, consists of four 20,000 gallon storage tanks and two 10,000 gallon storage tanks. St. B-15; P-245, Appendix I. Tank Farm No. 2 has two 20,000 gallon storage tanks. P-245, Appendix I. A quonset hut (“Quonset Hut No. 2”) is located to the west of Tank Farm No. 1 near the north property boundary. Id. Other locations that figure in determining responsibility for contamination at the Site today are the filter room at the eastern edge of the Nashua plant, the solvent recovery room slightly to the southeast of the filter room, and certain roof vents in Building 58. Id. The twenty-two acre Nashua Site is bounded by Norton Company to the west and residential areas to the east and south. P-235. The northern boundary is marked by a New York Central Railroad track. P-235; St. A-6. Another residential neighborhood known as Maplewood and consisting of Alden, Craig, and Archibald Streets and Lansing Avenue from south to north, Route 32 to the east, and a railroad track to the west lies to the north of the railroad track. P-235; P-250, Appendix Y. II. Subsurface Conditions The land underlying the Nashua Plant is heterogeneous and contains rubble, sand, gravel, and finely pored materials such as silt and clay. Pockets of finely pored materials can be found within larger deposits of sand and gravel. TT at 2695, 2976; P-198. I base these conclusions on a trial exhibit, P-249, created by Nashua that depicts a geological cross-section of the lands at the north of the site underlying Quonset Hut No. 2 and the two tank farms as well as on trial testimony. TT at 1935-36; P-249. Nashua’s expert geologist created trial exhibit P-249 after examining boring logs that described soil types at the many locations where Nashua’s consulting firm drilled into the soil for various purposes. Where no actual borings had been made, the geologist estimated soil type based on the nearest borings and general principles. Groundwater saturates much of the subsurface environment. P-198 at 7. The zone of saturation, known as the water table, is found at varying depths below the surface. Id. The water table fluctuates vertically in response to seasonal cycles and storms. Id. In addition, water flow direction varies over time. Although the ground water flows predominantly to the north and northeast, it includes, at least at times, a south or southwesterly component. Several storm sewers run under the plant, converge, and ultimately flow eastward into a municipal storm sewer. Id. These sewers include leaking clay pipe and corrugated metal pipe. Id. Two main west-east sewers cross the former location of the underground solvent lines. P-246, Appendix II. There are also sanitary sewers underneath the Site III. History of Solvent Loss During Norton’s Stewardship A. Norton’s Solvent Usage Each of the six tanks in Tank Farm No.l, which were installed by Norton in the mid-1950s, had a connection to an underground line that transferred solvent from the tanks to various manufacturing facilities within the plant. St. B-17, 22, 24; P-3, ¶ 79. Both Norton and Nashua — at various times — stored the solvents toluene and tolusol in the 20,000 gallon tanks and methyl ethyl ketone (“MEK”) in the 10,000 gallon tanks. St. B-20-21. Tolusol is a combination of toluene and heptane. St. G-88. Norton used each of these solvents in its tape manufacturing process. St. B-20-B-26. A seventh pipeline led from a solvent recovery operation to Tank Farm No. 1. St. B-23. In 1961 or 1962, Norton installed a solvent recovery operation. St. D-47. Prior to that time, Norton emitted all of the solvent in vapor phase to the air. Hoyt Dep. Tr. at 10. In addition, Norton discharged decanter water from the solvent recovery lines to the storm sewer. Muller Dep. Tr. at 61,176. Former Norton employees, who became Nashua employees in 1974, testified concerning the volume of Norton’s purchases of solvent. Arthur LaBreque had responsibility for either the requisition or procurement of solvents for Norton during the following periods of time: November 1969 to December 1972 and December 1973 to March 1974. TT at 231-235. He estimated that Norton purchased three to four tank trucks a week of solvent between November 1969 and late 1972 and that each truck load contained between 6500 and 6800 gallons of solvent. TT at 283-85. James Susko worked in quality control at Norton from the mid 1950s until 1972 or 1973. Susko Dep. Tr. at 5-8. He testified that Norton used toluene and tolusol as solvents and that Norton purchased between two and three tank loads of solvent a week. Id. at 20-21. Assuming conservatively that Norton purchased an average of two and a half tank loads of solvent a week during the late 1960s and that each load contained 6650 gallons of solvent, Norton’s average annual solvent consumption approximated 865,000 gallons. B. Solvent Related Complaints and Responses Beginning in the mid 1960s, Town of Colonie employee Thomas Burke responded to odor complaints in the Maple-wood neighborhood north of the Site. Burke noted “a strong chemical odor in the manholes along Alden St.,” the street closest to the Site and a weaker form of the same odor in Alden St. residences. TT at 133,136. When Burke actually entered manholes in the sewers, the odors quickly made him dizzy. TT at 145. He also smelled a weaker chemical odor in the manhole on Craig St., to the north of Alden and stronger odors in the 3rd Avenue and 27th St. area to the east of the Site. TT at 145-47. Burke continued to respond to complaints in the Alden St. neighborhood until 1975. TT at 143. Early in 1967, Norton received a complaint from Mutual Coal Co., located to the east of the Site, of a strong odor of solvent in its wash room. P-21; TT at 130; P-235. In response, Norton tested the decanter condensate water in its solvent recovery system and found that it contained 1% alcohol and an undetermined amount of toluene. P-21 at 4. In November 1968, The Town of Colonie Fire Department and Albany County Health Department responded to complaints of solvent fumes in sanitary and storm sewers along Alden St. P-18, P-19; P-94. Using an explosion meter to determine solvent concentration in manholes in both sewer systems, workers consistently found solvent fumes at explosive levels as far north as Alden St. P-19; P-94. During Norton's own investigation, employees witnessed solvent leaking into a sanitary system manhole at Alden St. P-19. Norton confirmed the presence of toluene and tolusol in water from the sewers. P-18. At some time prior to February 6, 1969, Norton conducted a “material balance study ... to determine if the amount of solvent received and recovered was the same as that which was used.” Id. “Within the accuracy of the metering devices ... there was no evidence of solvent loss.” Id. However, in November, 1969, at the request of Norton’s accounting department, Arthur LaBreque investigated a $60,000 variance between solvent purchased by Norton from July 1968 to July 1969 and verifiable inventory. TT at 286-89. LaB-reque found that Norton consistently lost about a tanker truck load of solvent a week. Id. Again using a figure of 6,650 gallons for a tanker truck load, the annual loss would have been almost 346,000 gallons. At first Norton Personnel assumed that the escaped solvent came from the solvent recovery system decanter and installed a heat exchanger and water tower to flash the solvent out of the decanter effluent before it entered the sewer system. P-19. On January 15, 1969, Wilbur E. Kidder, Norton’s industrial relations manager, wrote to Town of Colonie Chief Fire Inspector Howard C. Wilson to advise him of these steps but conceded that “there are still some puzzling factors such as the presence of toluene in the lines clear up in Craig Street, upstream from any drains in our plant.” P-15. Kidder assured Wilson that Norton would pressure test its underground solvent lines. Id. On January 22, 1969, Kidder advised Wilbur that the pressure tests revealed “that one of our tolusol lines was leaking.” P-16. In a subsequent internal memo dated February 6, 1969, R.L. Muller of the Engineering Department advised that three of the lines were porous and would not hold pressure. P-18 at 2. Muller requested approval to replace all the solvent lines “in order to prevent a reoccurrence of this hazardous condition which could have resulted in legal action by The Town of Colonie or the Albany County Department of Health, or in a sewer explosion if the vapor were ignited.” Id. He further noted: “After the completion of this project, there will be no underground solvent lines in the plant which will preclude the possibility of future sewer contamination from this source. The piping will all be over the roof where by a visual inspection even the slightest leak can be detected and repaired.” Id. Norton sealed off the underground solvent transfer pipelines, abandoned them in place, and installed overhead lines. St. E-69. In late summer 1969 — after the underground pipelines had been removed — solvent fumes ignited, blowing off storm sewer manhole covers inside and outside the northeast corner of Building 61 (at the northeast corner of the Nashua Plant). LaValley Dep. Tr. at 27-28; Mulheren Dep. Tr. at 174-75; Hoyt Dep. Tr. at 127; P-19. Norton excavated a section of the pipe inside Building 61 and found several inches of solvent floating on the water table under the building. P-19. Workers dug a test pit, dropped a hose into it, and pumped the liquid, a mixture of solvent and water, continuously until the pit was empty. St. E-79. Initially, workers repeated this process daily, and the amount of solvent in the pit decreased over time. St. E-81-82. This pit remained open from September 1969 to December 1970. P-19. When the workers stopped seeing any solvent at all, they let the pit stand for a week or so and then closed it. Muller Dep. Tr. at 99. About 3200 gallons of solvent, which Norton identified as tolusol, were recovered. P-19. During the pumping process, Muller observed “that whenever there was an accidental spill of solvent at the tank farm, a corresponding increase in the thickness of the solvent layer would take place inside Bldg. 61 within 24 hours.” P-19. To control this problem, Norton constructed a sealed concrete dyke around the storage tank farm and set up a procedure for pumping out the dyke when a spill occurred. Id. Norton also excavated two other test pits — one to the west and one to the east of Tank Farm No. 1 — and excavated them to the water table. St. E-70. Employees found solvent floating on the water only in the east test pit. St. E-71-7S. The company left the east test pit open for two to three months and pumped water and solvent from it. St. E-74-75. In 1971, The Albany County Sewer District (“ACSD”) and Town of Colonie began to construct new sewer lines in the Maple-wood neighborhood along Alden Street and Route 32. St. F-85, P-235; TT at 85. C.T. Male Associates, Inc. (“C.T.Male”) was the engineer of record. TT. at 86. A subcontractor drilled a bore pit at a jog in the sewer underneath the railroad tracks, almost directly north of Tank Farm No. 2, and northwest of the former solvent recovery lines and Tank Farm No. 1. P-235, TT at 88. In the course of this excavation, the workers noted an odd odor in the bore pit. TT at 93. Soil excavated from the pit had the same odor. TT at 98. When the excavation was completed and workers attempted to cut a hole in some sheathing, sparks from an acetylene torch caused a fire on the water. TT at 93. The substance causing the odor and the fire also caused employees who inhaled it for substantial periods of time to become lightheaded. TT at 95-96. CT Male’s supervising engineer, Thomas Vroman, observed a substance floating on the top of the water. TT at 97. On Monday, November 22, 1971, men working in the sewer found the bodies of two other workers in the bore pit. TT at 92. Autopsies established that the two men, who had been missing since Friday, November 18, 1971, had toluene in their blood, brains, and lungs. P-49; P-50. The autopsies did not reveal any other toxic substance. Id. The contractors returned to the job site shortly after discovering the bodies and continued to encounter solvent in the groundwater east of the boring pit, north of the railroad track and just south of Alden Street. TT at 102-105. Fire investigators found that toluene in manholes in the interceptor was at an explosive level. P-57; P-58. When the contractors attempted to weld a pipe to be used to carry a sewer pipe across Route 32 at Alden Street, the sewer ditch again caught fire. TT at 104-05. Some attempts were made to remove solvent from the sewer ditch, but the record does not indicate their effectiveness. TT at 105-06; P-65-66. All that is known is that by January 3, 1972, two hundred gallons of toluene had been collected. P-94. IV. Nashua’s Purchase of the Plant Nashua purchased the pressure-sensitive tape manufacturing division from Norton on February 24, 1974. St. A-7. Norton did not disclose the leaks from the solvent recovery line or the resulting contamination and deaths at the time of the sale. TT at 571-75, 603. Nevertheless, Norton argues that Nashua should have known about the leaks because (1) Nashua, which already used solvents in some of its other operations and thus knew of their dangerous propensities, had access to all of Norton’s business records prior to sale; (2) Nashua hired most of Norton’s employees; and (3) Nashua employees conducted a physical inspection of the premises to assess safety and environmental issues, TT at 608; Potter Dep. Tr. at 68; D-120. In addition, the evidence establishes that Nashua knew that some solvent was escaping into the air because solvent recovery systems at the time were only about 85% to 90% efficient and certain emissions were not picked up in the solvent recovery system. Potter Dep. Tr. at 65-66. I con-elude that although Nashua should have been and probably was aware that solvents likely contaminated the Site to some extent, no credible evidence supports the conclusion that Nashua either should have known or did know about the massive leaks in the 1960s. V. Norton’s Solvent Usage After the Sale Norton leased Building 61 for its Bear-Tex Operation, in which it continued to use solvents including methyl isobutyl ketone (“MIBK”), xylene, and toluene and tolusol in small amounts. O’Brien Dep. Tr. of 7/22/94 at 162-64; P-27; P-38; TTat875-76, 2090. Norton dumped certain of these solvents including MIBK in the Bear-Tex sump pit. TT at 868-69. MIBK and toluene were found in the sanitary sewer effluent downstream from the Beartex sump pit. P-195 at 3. Norton also spilled solvents on pavement outside Building 61. P-27; O’Brien Dep. Tr. of 8/12/94 at 113. Norton replaced this area of pavement in September 1989 because of the deterioration caused by the spills. O’Brien Dep Tr. of 8/12/94 at 108-13. Soil samples in the area replaced contained MIBK. P-198 at 18, TT at 2090, 2144. VI. Nashua’s Tenure A. Solvent Usage The parties agree that Nashua initially used both toluene and tolusol in its tape manufacturing process but disagree as to when Nashua stopped using tolusol. St. G-87, 89. Norton contends that Nashua used tolusol or hepsol, another solvent that contains both heptane and toluene, until at least 1989. Norton FOF 60. Norton relies on (1) Nashua’s 1982 and 1984 certificates to operate an air contamination source, which list heptane as a contaminant, D-17, D-23, D-24, D-25, D-26; (2) Nashua’s waste data sheet dated February 20, 1986, which lists toluene and heptane as constituents of adhesive waste, D-22; (3) an industrial chemical survey from September 1984 listing toluene and tolusol as hazardous waste, D-68; (4) a hazardous materials report from December 1984 listing toluene and tolusol, D-69; and (5) Nashua’s interrogatory responses 65 and 66 concerning stack and fugitive emissions, P-203. Defendant also relies on Louis Ethier’s testimony that, to the best of his recollection, Nashua bought a heptane blend until at least 1989, Ethier Dep. Tr. at 27-29, and deposition testimony from Ralph Hoyt that Nashua used tolusol in 1984, Hoyt. Dep. Tr. at 121. At another point, however, Hoyt testified that Nashua used tolusol for only three or four years after it began operations in 1974. TT at 53. Some of the cited documents do not support Norton’s position. For instance, the reference to tolusol vapors in D68 is limited to the period from 1961 to December 31, 1981. D-68 at 4. And, the cited interrogatory responses refer to toluene only. However, in 1984, Nashua did report that it had 7500 gallons of tolusol on the premises. D-69 at 2. Moreover, Nashua requested permission from DEC to operate an air contamination source in 1982 and 1984 and listed heptane as a contaminant. D-17, D-23, D-24, D-25, D-26. Nashua claims that its use of heptane ended in late 1981 or early 1982. Nashua FOF 59. It relies in part on requisition sheets that show no purchases of heptane, tolusol, hepsol and RMT 825 and 825A (forms of hepsol) after 1981. P-112, P-112A, P-117A. In addition, Nashua’s technical director during the late 1970’s and 1980’s, Paul Sartoris, testified that Nashua stopped using heptane for economic reasons around 1980. TT at 412-414. Arthur LaBrecque, who ordered Nashua’s raw materials, testified that Nashua last purchased tolusol in February 1981 and last purchased Hepsol in August 1981. TT at 232, 273-276. Finally, Rick Lawton, who became Nashua’s manager of regulatory affairs in 1989, explained that when he renewed Nashua’s permits in 1990, he found they were inaccurate in that they listed pollutants including heptane that Nashua no longer emitted. TT at 855-56. He therefore corrected the DEC printout and sent it back. TT at 856. The more credible documentary and almost all the testimonial evidence supports Nashua’s claim that it stopped purchasing and using tolusol and heptane in the very early 1980s although it continued to store tolusol thereafter. The witness who testified to Nashua usage after 1981 contradicted himself, and the witness who testified to purchases after 1981 was contradicted both by the documentary evidence and by the other witnesses. Although the permitting applications constitute some evidence that Nashua used heptane and/or tolusol after 1981, they are outweighed by the other evidence of record and were explained, at least in part, by Lawton’s testimony. B. Nashua’s Leaks and Spills The evidence established several leaks and spills during Nashua’s operation of the Site. In 1983, a mechanical failure in the decanting area caused approximately 700 gallons of toluene to discharge to the sewer line leading to the Albany County Sewage Treatment plant. Moore Dep. Tr. at 21. Another such incident two or three years later resulted in a discharge of between 900 and 1288 gallons of toluene into the sewer system. Id.; Compare D-81 with D-234. After the second problem, Nashua agreed to corrective measures and to routine inspections by the sewer district. In 1985, toluene being transferred from one tank to another in Tank Farm No. 1 overflowed. TT at 1528. A machinist notified plant managers including James Sus-ko, and they immediately shut the pump down. Id. Susko went to the scene and observed solvent sliding down the outside of the tank and into the concrete bermed area. Id Within the next hour, Nashua pumped about 350 gallons of water and solvent from the bermed area. TT at 1528, 1534. Susko testified that he did not observe solvent on the ground or any place other than inside the berm and that the overflow pipe was too small to enable the solvent to escape the berm. Susko Dep. Tr. at 79-80, 198. Other spills from the tank farm also flowed into the concrete basin beneath the tanks. Ethier Dep. Tr. at 61. On examination in 1992, the concrete basin was pock marked and cracked, contained epoxy patches that had delami-nated, and had standing water and solvent in it. TT at 1072-86, 1125; D-136-38. However the record does not indicate how deep the cracks were, and the presence of standing water suggests that the basin did not leak. In April 1986, a backflush solvent release in the filter room inside the plant caused approximately 450 to 700 gallons of solvent (90% toluene and 10% solids), to drain onto the six-inch concrete floor of the filter room. Moore Dep. Tr. at 46-47, D-232. Most of the spilled material evaporated, but Nashua conceded that “it is possible that a small quantity of material leaked into a storm sewer drain and found its way to the Hudson River.” D-232. However “[a] water sample ... taken at the storm sewer discharge point and in-house testing found no toluene contamination.” D-232. Some of the toluene drained onto an asphalt area outside the filter room. Moore Dep. Tr. at 98-99. Nashua removed the contaminated asphalt. Id. at 112. Malfunctions in the solvent recovery system during Nashua’s ownership sometimes pumped solvent to the roof of the Solvent Recovery Room. Ethier Dep. Tr. at 72-76. Solvents reaching the roof ordinarily were bermed with Speedy-Dry, an absorbent, and left to evaporate, but on one occasion about 15-20 gallons escaped to an adjacent alley. Id. at 74-75. Nashua employees put Speedy Dry on this spill and left it to evaporate. Id. at 75-76. In addition, certain portions of the floor in the recovery room deteriorated from solvent that dripped on it. D-129. Sometimes solvent was pumped out into the roadway adjacent to the Solvent Recovery System. Ethier Dep. Tr. at 72. Norton identifies the solvent recovery decanter as another potential source of contamination. After water from the solvent recovery decanter went through the air stripper, Nashua discharged it to the sanitary sewer, which flows off Site and ultimately to the Albany County Sewer District. Susko Dep. Tr. at 126-27. Nashua also produced both stack and fugitive emissions of toluene. P-203, Interrogatory Responses 65, 66. Finally, Norton identified Nashua’s storage practices as a potential source of a release to the subsurface environment. Various historical documents demonstrate a certain sloppiness on Nashua’s part in storing chemicals in and around Quonset Hut No. 2. See D-10 (April 18, 1986, memo stating that “several” of the approximately 500 “empty” drums stored mainly outside the quonset hut “had a small quantity of product left in the drum”); D-11A (September 10, 1986, hazardous waste meeting minutes stating that although “overall condition of hazardous waste accumulation and storage was very good,” the drums in Quonset Hut No. 2 were in questionable condition); D-45 (internal memo dated May 13, 1986, noting storage of “numerous drums, pails, etc. of resins, solvents, oils, and unknowns throughout the plant); D-46 (internal memo dated April 22, 1987, noting that empty drums had been stored in the quonset hut on their sides and were leaking onto the floor”); D-65-66 (inspection log and checklist showing one leaking drum outside Quonset Hut No. 2); D-229B (March 11, 1986, inspection log noting, “40+ drums, open, seeping saturant on ground outside hut .... 200 + drums (partially filled) of hard latex outside”); D-229C (inspection log dated March 26, 1986 stating that waste latex drums were stored outside Quonset Hut No. 2). Much of the hazardous waste stored in drums including latex, junk adhesive, banbury waste, stripper waste, waste oils, oily filters and rags, and floor cleaning and debris contained toluene, ordinarily in extremely low concentrations. D-89 (list of waste streams); TT at 1409-15. Nashua closed Quonset Hut No. 2 in June 1988. P-130; P-131 at 2. VII. The Investigative Process A The B-l Boring In 1988, Nashua wished to erect a calcium carbonate storage silo. St. H-95. To determine the suitability of the proposed area for a storage silo, Empire Soils conducted a geotechnical investigation. Id. The company drilled a test boring (Empire B-l) at the northwest corner of Tank Farm I and east of Tank Farm II and Quonset Hut No. 2. St. H-96; P-235. At a depth of ten feet, Empire Soils encountered groundwater, smelled a solvent odor, and found a 13-inch thick layer of solvent floating — within a hollow stem augur — on the top of the water table. St. H-97-98; D-169 at 2; P-153. A Nashua analytic chemist analyzed a sample from the boring and found that the majority of the sample was toluene with some heptane. Ellett Dep. Tr. at 8, 19, 22. Nashua did not report these results to EPA or the New York State Department of Environmental Conservation (“DEC”). TT at 476-79, 516-17. Nashua’s in-house counsel, Arthur Lyman, explained that he believed no new spill had occurred and that the contamination resulted from Norton’s 1969 spill. TT at 516-17. Lyman did contact Hank Jackson, Norton’s in-house lawyer, who told Lyman that all appropriate authorities had been contacted at the time of the 1969 spill. TT at 517-19. B. EPA Notification On August 31, 1989, EPA notified Norton and Nashua of their potential CERC-HA liability for contamination outside Building 61. P-157; TT at 520-21. EPA took this action after Stone Management, a property owner to the west of Building 61, complained of an odor or discoloration in storm water at its facility. TT at 520-21; O’Brien Dep. Tr. of 7/22/94 at 153-154. Prior to issuing the notices, EPA and DEC, which became the lead agency in the investigation, had limited sampling results suggesting the presence of volatile organics, metals, and petroleum hydrocarbons in the storm water and/or storm water sediment. P-160 at 7. C. The Limited Cooperative Investigation Norton and Nashua jointly hired ERM Northeast, an environmental engineering firm, to conduct an investigation of the Site. O’Brien Dep. Tr. of 7/22/94 at 154. ERM’s October 24,1989, final report found three areas of potential contamination— the solvent recovery room in Building 59, the Bear-Tex Premises, and the tank farms (with particular reference to the 1960s leaks). P-162 at 5-9-5-11. ERM recommended further investigation of subsurface conditions in areas surrounding Building 61, the solvent recovery area, and the tank farms. Id. at 7-3. On March 5, 1990, Nashua demanded that Norton assume the costs of Site investigation and clean up. P-231. Norton offered to split the cost of the clean-up equally, but Nashua declined. P-231; D-269; TT at 1230-32. D. The Dunn-Rust Investigation In October 1989, Nashua retained Dunn Geoscience (“Dunn”), which later became RUST Environmental & Infrastructure, Inc. (“RUST”) (collectively, “Dunn/ RUST”), to conduct further site investigations. TT at 845-46, 1429. Dunn/RUST, in consultation with DEC officials, amended the ERM work plan. TT at 1429-30, 1768. Frank Williams, Dunn’s Senior Project Manager and a Nashua expert at trial, outlined the scope of the subsequent investigation. Based on ERM’s work and its own, Dunn/RUST identified several areas of potential release of solvents including the two tank farms, Quonset Hut No. 2, the Bear-Tex sump and doorway spill areas, the filter room, the solvent recovery area, roof vents in Building 58, and the former underground solvent transfer lines, which ran from the tank farms into Building 61. P-245. The company then planned sampling to address these potential release areas. TT at 1815-16. In essence, Dunn/ RUST looked for the presence of solvents at locations close to areas from which the solvent might have migrated into the subsurface environment. The principal solvents at issue — toluene and tolusol — are both non-aqueous phase liquids (“NAPLs”), or liquids that are immiscible in water. They are also light non-aqueous phase liquids (“LNAPLs”) or lighter than water liquids that tend to float on top of the water table. TT at 3113; P-198 at 7-8. In their earliest soil testing, Dunn/ RUST personnel drilled test borings (“TB”) one through seven along the northern and eastern borders of the Site, and, with one exception, found low levels of toluene. TT at 1834; P-248, Appendix IV. At TB-5, located at the north of the property to the immediate west of Tank Farm No.l and northwest of the former solvent recovery lines, the researchers “observed a sheen on the soil which was indicative of a nonaqueous-phase liquid (“NAPL”) ... in the area of the water table roughly about 8 to 10 feet below surface.” TT at 1834. Laboratory testing showed that the sample had “very elevated levels of heptane and toluene relative to the other borings at this location.” Id.; see also P-248, Appendix IV. Dunn/RUST also performed an initial round of groundwater testing using five wells that rimmed the perimeter of the plant. None of these wells — DGC-1 at the southwestern corner of the site; DGC-4, the most northwestern of the wells, located slightly to the west of Quonset Hut No. 2; DGC-5, also at the northern edge of the plant and slightly to the east of Tank Farm No. 1; DGC-3 on the eastern side of the plant slightly northeast of the filter room and also northeast of the solvent recovery room; and DGC-2, southeast of the solvent recovery room — had measurable toluene or heptane in samples drawn in December 1989. P-246, Appendix II; TT at 1885. The researchers were surprised by these results because TB-5 had such a high level of toluene that they anticipated significant results at all locations down gradient of that boring. TT at 1835. Dunn/RUST also received early storm sewer analytical results for manhole 3, located south of Quonset Hut No. 2 and the two tank farms, roughly equidistant from tank farms 1 and 2; manhole 12 in Building 61, southeast of the Bear-Tex Sump and doorway and west of the former solvent transfer line; and manhole 6, east and south of the solvent recovery room and east and north of the filter room. P-247, Appendix III; TT at 1835-36. Dunn/ RUST found no or very little toluene and heptane in the water from each of these locations. There were higher levels of the two chemicals (and other NAPLs) in the sediment because NAPLs have a greater affinity for soil than water. TT at 1836. Early analytical results for MH-FC and MH-1, both located on the sanitary sewer trending south from the Bear-Tex Premises, “were significantly different,” showing “some toluene” and “quite a few other chemicals” such as “MIBG, methyl isobu-tyl butane, MEK, methyl ethyl ketone; styrene, and in one instance some 1.4 diehlorobenzene.” TT at 1836; P-247, Appendix III. After receiving these early results, Dunn/RUST submitted a report to DEC and, in consultation with DEC, agreed on additional work. TT at 1837. The new work included a soil gas survey in the vicinity of TB-5 to determine how far the contamination had spread and some additional water levels in the monitoring wells. TT at 1838. Dunn hoped to establish the direction of ground water flow through the water levels. Id. The soil gas survey involved “collecting small amounts of the air ... in the soil ... about two or three feet below the surface” and analyzing it in a field gas chromato-graph. T-1843-44. Although the field gas chromatograph allows for immediate results, it has limitations in identifying specific NAPLs. TT at 1850-51. Therefore, Dunn/RUST used it principally to identify the total concentration of volatile organic compounds (“VOCs”) in any particular sample. TT at 1851. VOCs include volatile solvents such as heptane and toluene. TT at 1720. In addition, the type of soil influences the ability of the ground to deliver air to the field gas chromatograph, with air being more easily extracted from loose soil such as gravel than from tight soil. TT at 1852-53. Consequently one cannot conclude that contamination is not present at a particular site from negative results at that location. June 1990 soil gas testing focused on the area around the TB-5 boring, the area below Building 61’s concrete floor, an area just east of manhole MH-1 along the sanitary sewer line, and bedding adjacent to the storm sewer line east of manhole MH-5. TT at 1855-56. High levels of VOCs near the northern property line and surrounding TB 5 concerned DEC representative Margaret O’Brien, so she asked Dunn/RUST to take measurements “off the property to the north of the facility along the railroad tracks.” TT at 1855. Dunn/RUST took four additional samples north of the railroad tracks and off the Site and did not find contamination. In general, Dunn/RUST found elevated levels of VOCS “in the general area around the tank farm and just to the south of it.” TT at 1856; P-248, Appendix IV. However, there were also some negative results in this area. Id. There were very low readings or non-detectible readings at the points outside the manholes where contamination had been detected. TT at 1858. In mid July 1990, discovery of contamination in Building 58 interrupted the planned testing. TT at 1858; P-248, Appendix IV. Under Frank Williams’ observation, Dunn/RUST’s geotechnical department conducted geotechnical borings. TT at 1859-60. Dunn/RUST made the first borings, shown on P-245 as B-l, B-2, and B-6, in the southwest area of Building 58. TT at 1859, P-245, Appendix I. Northwest of this area, they dug borings B-3 through B-5. Dunn/RUST discovered contaminated soil at B-l and extremely elevated levels of VOCS at B-3. TT at 1861. As it turned out, B-l was contaminated with a very old fuel oil. TT at 1862. However, the results from B-3 “indicate[d] very elevated concentrations of heptane and toluene.” TT at 1864; P-248, Appendix IV. Later soil gas samples in the area also indicated high levels of VOCS. TT at 1865, P-248, Appendix IV. Dunn/RUST reported all these results to DEC and during the remainder of the summer formulated an additional work plan. TT at 1866. After reaching agreement with DEC on the plan, Dunn/RUST implemented it in October 1990. TT at 1867. Pursuant to the plan, the company installed three new monitoring wells in the vicinity of TB-5: DGC-6 inside Building 61, just west of the former solvent transfer line; DGC-7, just west of Tank Farm-1; and DGC-8, just north of Tank Farm 1. TT at 1868; P-246. Dunn/RUST also took a deep soil boring just north of the Bear-tex Sump and Doorway spills. Id. Finally, the company installed wells DGC-9 and DGC-10 toward the northeast of the property to monitor PCB-contamination for a matter unrelated to the toluene/heptane investigation. Id. Groundwater sampling conducted in November 1990 revealed elevated concentrations of toluene in each of the new wells (DGC-6, DGC-7, and DGC-8) installed around TB-5. P-246, Appendix II; TT at 1870. Dunn/RUST also sampled all the pre-existing wells as well as DGC-9 and DGC-10 and found no evidence of toluene or heptane in these wells. Id. Williams testified that although the analytical results at DGC-7 did not show detectable levels, heptane likely was present in the groundwater because it was present in the adjacent soil. TT at 1882-83. He indicated that “[mjolecules of heptane are constantly leaving the adsorbed phase [in the soil] and dissolving into the groundwater and they are constantly going from the dissolved phase in groundwater back to the adsorbed phase .... There is an equilibrium established there.” Id. Williams also believed that DGC-8 contained heptane at the time of the 1990 tests based on later tests performed by Dr. Joseph Co-meau. TT at 1885-86; see below at 22-23. Dunn/RUST reported the results of this round of testing to DEC in January 1991. TT at 1886. Thereafter, there was a hiatus in investigatory activity while Dunn/ RUST assessed the relative appropriateness of the RCRA and CERCLA programs for the Site. TT at 1888. Dunn/ RUST evaluated the work that would be required under each program, estimated its cost, and evaluated clean up standards. TT at 1890. On June 4, 1993, Dunn/RUST sent Luanne Whitbeck; O’Brien’s successor at DEC, a plan for work under the RCRA program. P-179; TT at 1892. DEC requested a more definitive work plan but approved the concept of the RCRA plan. TT at 1896-97; P-178. Dunn/RUST completed the work plan in November 1993 and transmitted it to Norton. TT at 1901-03. The record does not indicate that Norton objected to the proposed work plan. In December 1993, Norton’s consultant, Eder Associates, conducted groundwater sampling and gave Dunn/RUST splits of their samples. Toluene was detected at DGC-6 and DGC-7. TT at 1921-22; P-246, Appendix II. DEC gave Dunn/RUST comments on their work plan on December 29, 1993. TT at 1923. In April 1994, Dunn/RUST submitted the revisions that DEC requested along with a work safety plan. TT at 1923-24. DEC responded with additional comments and requests for information in August of 1994. TT at 1925. In late October 1994, DEC requested more information, TT at 1928; P-191, which Dunn/ RUST supplied on January 20, 1995. TT at 1929; P-195. In August 1995, Dr. Joseph Comeau tested groundwater from DGC-8, using a more sophisticated methodology than had been used previously, and found both toluene and heptane. TT at 1932; P-196; P-246. Comeau performed Ms analysis to test the validity of Williams’ opinion that heptane present in the ground water at DGC-8 evaded detection under the less sophisticated analytical protocol. TT at 640-43. VIII. Causation In assessing the cause of the contamination found at the Site today, I rely on the analytical data from the Site, the geology of the Site, and the expert testimony. Because each party stipulated to the other party’s experts’ qualifications, St. C-6, and Norton stipulated to the validity of Dunn/ RUST’s analytical data except for the August 1995 results from DGC-8 and all data from DGC-1, I will review the experts’ credentials only briefly. Frank Williams and Dr. Gerald Lauer testified for Nashua. Williams, a geologist, has substantial experience in site investigations including work on the Love Canal. TT at 1681-1688. Lauer is a limnologist who also has extensive site investigation experience and is knowledgeable concerning the effect of water supply contaminants on water supplies. TT at 2656-2674. Norton’s experts were William Warrren and Dr. Olin Braids. Warren, a hydro geologist, has been performing site investigations since 1984. TT at 3024-25. Braids, whose academic background is in soil chemistry, has investigated areas of hazardous waste contamination since the early 1970s. TT at 3553, 3557. A. Nashua’s Contributions to Site Contamination Braids conceded that all but one of Nashua’s spills and leaks could not account for the contamination found in Williams’ investigation. TT at 4009-10. The sole exception to Braids’ concession was the mid-1980s tank farm overflow. Because Warren made similar concessions, TT at 3402-03 (knows of no Nashua releases between 1990 and 1993), 3412 (filter room spill would not have led to significant subsurface contamination), 3416-17 (spills from solvent recovery area could not have accounted for contamination at B-3, DGC-6, DGC-7, DGC-9 or TB-5), 3417-18 (no experience that would lead him to believe fugitive or stack emissions caused contamination of site), 3388-89 (Norton attorney’s representation that Warren has nothing to offer concerning cause of contamination other than hydro geological conditions) and Nashua’s experts testified persuasively that for several reasons, Nashua’s spills and leaks did not cause the contamination found on the Site, TT 2073-2135 (Williams); TT 2780-2791 (Lauer), the only controverted potential release into the subsurface environment is the mid 1980s tank farm overflow. Braids’ claim that the tank farm overflow could have caused the contamination detected at the Site rests on his assumption that solvent came out in a trajectory and “some” escaped the berm. TT at 3870-71. This speculation contradicts the competent evidence in the record. Susko testified that he observed no solvent on the ground and that the size of the overflow pipe was calculated to keep solvent from overflowing the berm. I therefore find that Nashua’s identified spills and leaks did not contribute to the identified contamination at the Site. However, Braids also testified that the contamination likely was attributable to an aggregate of small unreported spills on Nashua’s watch. Although Braids could not identify a leak or spill during Nashua’s tenure that (a) contained heptane or (b) could have caused the contamination identified at the site, it was his experience from other facilities that leaks and spills sufficient to cause the contamination at issue here often went unreported. TT at 3873. Braids’ testimony concerning unreported spills is speculative and unrelated to any foundation concerning Nashua employees’ work habits or reporting practices. I therefore reject it as insufficient to support a finding that any Nashua spill, leak, or poor housekeeping practice caused the contamination that Dunn/RUST identified at the site and find that Nashua is not responsible for the identified contamination on site. I do find, however, that Nashua is jointly responsible with Norton for a potential area' of contamination under the solvent recovery room. Williams conceded that chronic dripping of organic condensate in the plumbing of the solvent recovery room during the Nashua and Norton eras probably contributed to some solvent contamination in the top inch or two of soil immediately beneath the solvent recovery room. TT at 2111-13, 2143. B. Norton’s Contribution to Site Contamination 1. The Bear-Tex Premises Williams and Lauer testified that Norton’s practices at the Bear-Tex premises caused contamination immediately outside the Bear-Tex Premises and in the sewer line leading south from the premises. TT at 2090-92, 2750-51. Norton did not controvert this testimony and did not submit any proposed findings of fact concerning the Bear-Tex Premises. I therefore find that Norton is responsible for contamination in these areas. 2. The 1960s Leaks Norton concedes that the 1960s leaks occurred but hotly disputes the persistence of solvent from those leaks at the levels and in the locations revealed by Dunn/RUST’s testing. In assessing the likelihood of persistence of the 1960s contamination into the 1990s and beyond, I examine first the extent of the leaks. Williams characterized the leaks as massive relying on the following facts. Leakage from three lines persisted at least from the first complaints of solvent odor in the Maplewood area in 1966 until Norton’s removal of the lines in January 1969. TT at 2004, 2009. This leakage was continuous because centrifugal pumps remained on at all times. TT at 2010-12. Moreover, solvent spread over a large area. TT at 2015-24. Finally, according to Williams, LaBrecque’s testimony showed a loss of 200,000 gallons of solvent in a six month period. TT at 2044-45. Lauer used a different methodology to determine the extent of the leaks. He estimated two different areas that the spill may have covered by (1) hypothesizing a circle with a radius extending alternatively from the southern and northern ends of the solvent transfer line to Craig St., (2) assuming that the average thickness of mobile LNAPL was half an inch within that circle, (3) making'certain assumptions concerning soil porosity based on the geological data in the record, and (4) assuming that certain areas of the circle would not be saturated because of the prevailing water flow in the area. TT at 2738-40. Assuming that the leaks occurred at the northern ends of the solvent transfer lines, Lauer estimated that the mobile LNAPL in the site to have been approximately 94,000 gallons and the residual LNAPL to have been approximately 408,000 gallons. TT at 2747. Lauer testified that larger amounts of LNAPL would have remained in the soil and groundwater if the leaks occurred at the southern end of the lines or the whole circle was saturated. TT at 2738-2746. Although Braids maintained that he did not need to know how far the LNAPL spread to determine whether the remaining contamination at the Site resulted from Norton’s leaks, TT at 3671, he estimated the spill at between 26,400 gallons at the low end and a million gallons at the high end, TT at 4011. Braids’ figures referred to the amount of LNAPL in the ground at any one time, not the entire volume of the spill. TT at 4012. Braids did not explain his methodology at trial. I find, based on the LaBrecque testimony concerning the large amount of solvent unaccounted for in a very short period of time, the duration of the leaks, and the spread of the solvent, that the leak was indeed massive and almost certainly exceeded 500,000 gallons. The parties also agree that a portion of the mobile LNAPL left the Site and surrounding areas via the storm sewers, the 1969 recovery pits, the sewer interceptor trench, and the 1971 recovery efforts. The difference here is one of emphasis. Braids testified that the west-east trending storm sewers and regional ground flow were extremely effective in removing mobile LNAPL from the site. TT at 3671-72; see also P-200 at 7-8; D-311. Lauer, however, pointed out that (1) there is little factual data to confirm that LNAPL entered the sewers continuously or at many locations; (2) much of the solvent obviously escaped the influence of the storm sewers because it could not have reached both the Maple-wood area and former Test Pit E in Building 61 between the two sewer lines without crossing one or both of the storm sewers; (3) while the storm sewers were above the water table, solvents could not have leaked into them; and (4) at least a portion of the storm sewer, which Lauer observed, was made of steel rather than clay and thus was less subject to infiltration, TT at 2712-13. Braids also placed more emphasis on the 1969 and 1971 recovery efforts than did Lauer and Williams. Despite these differences in emphasis, Nashua’s experts did not controvert Braids’ bottom line conclusion that the mobile LNAPL largely had left the site by the by the mid 1970s. TT at 3671-76. I find that most of the mobile LNAPL exited the site by 1975 but that because of the duration and volume of the spill as well as the heterogenous subsurface environment which contained many soils that would tend to retain solvent, a large amount of residual LNAPL remained in the subsurface environment. In determining whether toluene and heptane present in the soil and ground water under the Site today results from the 1960s release, I must assess the effectiveness of natural processes to remove the remaining residual solvent from the site as well as the probability that the contamination remaining on site and detected in Williams’ investigation resulted from the leaking underground solvent lines. The second issue depends in part on the first because if natural processes removed all the contaminants from the site, the current contamination could not be Norton’s. However, Norton also contends that the patterns of contamination present at the site today are inconsistent with what would be expected from a massive discharge and more consistent with various unspecified housekeeping lapses on Nashua’s part. Braids testified that the residual concentration of solvent on the site dissipated in three principal ways: volatilization, which turns liquid into gas thus dissipating it; dissolution, which dissolves molecules into water and carries them away; and degradation in which bacteria “eat” the solvents. TT at 3677. Nashua’s experts conceded that dissolution would remove some of the contamination from the site although they noted that the combined effect of the two chemicals’ relatively low solubility and the lack of kinetic energy under the site would retard dissolution. TT at 2066 (Williams), 2765 (Lauer). The Nashua experts also vigorously contested the efficacy of the other two methods based on conditions at the site. They testified that (1) the pavement under the site as well as the hete-rogenous soils, which trap LNAPL, would minimize volatilization, TT at 2066 (Williams), 2764 (Lauer); (2) a lack of nutrients such as phosphorous and nitrogen necessary for bio-degradation would prevent that process, TT at 2068 (Williams); (3) because of the pavement, the subsurface environment lacks oxygen, which also is necessary for bio-degradation, TT at 2068 (Williams) and (4) the high concentration of toluene and heptane at the site initially would have been toxic to the very bacteria that feed on lower concentrations, TT at 2068 (Williams). Braids conceded volatilization would play only a small role in cleansing the site but contended that some volatilization would occur because the Site is not hermetically sealed. TT at 3684-85. Norton’s experts testified that probably there was some oxygen under the site both because rain water would bring oxygen and because the boring logs did not reflect mottling or hydrogen sulfide, which ordinarily are present in the absence of oxygen. TT at 3119-20 (Warren), 3701 (Braids). However, Warren conceded that he had no way of knowing whether there was enough oxygen to support bio-degradation and that the buildings and pavement at the site would reduce the available oxygen. TT at 3341 — 42. Braids also conceded that he did not know whether the necessary nutrients were present but believed that they were based on literature and personal experience concerning similar sites. TT at 3701. In addition to positing that the solvent it leaked dissipated long ago, Norton offers four reasons that the contamination currently at the site could not have resulted from the 1960s leakage. First, Norton’s experts contended that contamination from the 1960s could not have migrated to Boring B-3 in Building 58, southwest of the former solvent transfer lines, because that location is up gradient on the water table from the point of release “and you would not have that type of movement up that distance up gradient at this site.” TT at 3503 (Warren), 3749 (Braids). Second, they testified that if the solvent contamination found in the 1990s resulted from the 1960s release, one would expect to find similar readings of contaminants nearby. TT at 3108-09 (Warren), 3734-35 (Braids). Third, Braids also testified that solvent levels in the wells would not vary as drastically from reading to reading if they resulted from the 1960s release. TT at 3741-45. Finally, Braids contended that the relative toluene and heptane concentrations at DGC-8 were inconsistent with those that could be expected from a tolusol leak although he also acknowledged that if both toluene and tolusol.leaked, one would find different ratios of the two materials and that the ratio of toluene and heptane at TB-5 approximated those of tolusol. TT at 3900-01. In concluding that the contamination of boring B-3 by the 1960s release is inconsistent with the water table gradient, Braids and Warren relied on Warren’s belief that the water table tilted predominantly to the east and northeast and had no component of flow to the south or southwest at any point south- of the southernmost of the two west-east storm sewer lines that traverse the former solvent recovery lines. TT at 3078, 3084. Warren, in turn, did not consider 1990 data from DGC-1, located in the southwest corner of the Site, that tended to show a south/southwesterly flow because, in his opinion, (1) the DGC-1 1990 data was anomalous and (2) the filter on DGC-1 might well have been clogged with silt. TT at 3095, 3310. Warren also acknowledged that he had reviewed maps of areas adjoining the site which showed water flows different from north/north-east, but that he did not consider them because he knew nothing about the conditions under which they were created. TT at 3177-79, 3184. Williams and Lauer strongly differed with Norton’s experts’ claim that the isolated findings of contamination and/or the fluctuating levels of contamination indicated that the contamination could not have resulted from the leaking solvent transfer lines. Both testified that isolated hot spots were consistent with the way the contamination spread, because a massive spill such as this one would spread through the heterogenous soils of the Site via ganglia, with the solvent preferring the more porous soils. TT at 2142-43, 2736-37. Lauer also testified that differences in results for the wells on different sampling occasions was typical. TT at 2772-73. Because the proof does not conclusively establish certain Site conditions — e.g. how much oxygen, nitrogen and phosphorous are present under the Site — I cannot conclusively determine how rapidly natural processes have reduced or will reduce the contamination to non-detectable levels. Nevertheless, I conclude for three principal reasons that natural processes had not reduced contamination to undetectable levels by the early to mid 1990s when Nashua conducted its investigation. First, although all of the experts testifying had experience with contamination by solvents, none testified to personal familiarity with a site where a spill as large as this one disappeared within thirty years. Instead, the testimony on actual sites tended to show solvents such as heptane and toluene persisting for decades. See TT at 2671-74 (Lauer description of Nepera Chemical Manufacturing site in Harr