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Abarca, Raul Valencia, et al v. Franklin County Water District

January 5, 2011


The opinion of the court was delivered by: Oliver W. Wanger United States District Judge



This lawsuit arises out of a now-closed cooling tower manufacturing facility (the "BAC site") that pressure treated wood and was operated by entities formerly owned by the BAC Defendants ("BAC").*fn1 Plaintiffs, current or former residents of residential neighborhoods ("Beachwood") near the BAC Site,*fn2 allege that two contaminants from the BAC Site migrated from the treating area via groundwater, surface water, surface soil, private well, and air pathways to locations where plaintiffs were exposed to them.*fn3 Also named as defendants are various municipalities, water districts, and developers, including the Franklin County Water District, Merced Irrigation District, the City and County of Merced, and the Meadowbrook Water District.*fn4

Before the court for decision is BAC Defendants' motion to summarily adjudicate Plaintiffs' tenth, twelfth, thirteenth, and fourteenth causes of action. According to Defendants, Plaintiffs have failed to present any admissible evidence of actual exposure to contaminants from the BAC site, via any pathway, which was required under "Phase 1" of the Court's "Order Modifying Scheduling Conference Order." (Doc. 540.) The first phase of discovery was to focus on "whether contaminants from the former [] BAC Site, Franklin County Water District or the April 2006 Flood have ever reached any location where plaintiffs could have been exposed to them, and if so, when such contaminants arrived, how such contaminants arrived at the location, how long they were present, and at what levels they were present." (Id. at 1:14-1:28.) By this motion, the BAC Defendants assert that Plaintiffs have not met their "Phase 1" or "general exposure" burden, entitling them to partial summary judgment.

Plaintiffs opposed the motion on July 1, 2010, submitting over 3,000 pages of documentation and 168 exhibits. Plaintiffs' opposition is founded on their claim that they have presented "substantial evidence" in the form of expert opinion and analysis to show that contaminants migrated from the BAC facility to Plaintiffs' homes and/or properties. Plaintiffs further argue that the BAC Defendants' motions to exclude certain expert testimony fail because their criticisms go to its weight, not its admissibility.

Oral argument on the BAC Defendants' motions was held on October 6, 7, 13, 14, and 15, 2010, during which the parties presented argument and evidence relevant to the Phase 1 pathway exposure issues. The parties were permitted to introduce expert testimony on key scientific issues, namely the methodologies and assumptions used to model contamination via the groundwater and air pathways. The testifying experts were examined by counsel for Plaintiffs and Defendants, as well as the Court.*fn5

On October 22 and November 1, 2010, the parties were advised the Court intended to appoint independent experts under Fed. R. Evid. 706 to assist in the understanding and resolving the complex scientific disputes over groundwater and air modeling. The analysis included determining concentration levels of hexavalent chromium and/or arsenic in Meadowbrook Well No. 2 and surrounding areas (i.e., monitor networks and private wells), as well as the assumptions/calculations underlying the air model. The Fed. R. Evid. 706 Experts were appointed on October, 26. 2010 (Kenneth D. Schmidt, Ph.D. - groundwater) and November 1, 2010 (Chatten Cowherd Jr., Ph.D. and Richard Countess, Ph.D. - air).*fn6 The parties and the Court jointly prepared a list of questions for the experts, which were transmitted to the experts in early November. The independent expert reports were submitted to the Court on November 22, 2010.*fn7

The Fed. R. Evid. 706 experts were examined by the Court and parties on December 2, 3, and 15, 2010. Rebuttal testimony was permitted on a limited basis.*fn8

The Rule 56 motions were submitted for decision following summation arguments on December 28 and 29, 2010.


The facts underlying this case are summarized in the Court's previous Memorandum Decisions in this case, filed on November 13, 2008, May 18, 2009, and July 15, 2009, in brief:*fn10 approximately 2,100 Plaintiffs seek damages relating to two occurrences: (1) an April 2006 flood; and (2) alleged long-term contamination released from the former site of a cooling tower manufacturing facility operated by entities formerly owned by the BAC Defendants. The now-closed facility, which is the alleged source of contamination, is located in Merced, California, approximately 1,600 feet southwest from Meadowbrook Well No. 2 ("MWC-2"), which was the primary well supplying domestic water to the Beachwood community, until it was taken out of service in March 2008. Plaintiffs allege that MWC-2, which was operated by the Meadowbrook Water District, was contaminated by hexavelant chromium and total chromium in the well and from the aquifer, which drew on the contaminated plume during times of high water production, and exposed Plaintiffs to contaminants.*fn11

It is further alleged that the remaining defendants contributed to Plaintiffs' exposure to carcinogens and/or toxins based on their operation of a nearby drainage system (City and County of Merced), a collection system and ponds (Franklin County Water District), and an irrigation canal (Merced Irrigation District).*fn12 According to Plaintiffs, these municipalities and water districts were "direct participants" in the contamination based on their location and significance to the local community's water supply.

A. History and Remediation of BAC Site From 1969 until 1984, the BAC Site housed a cooling tower manufacturing facility and BAC-Pritchard, Inc., the operator/owner, used pressure-treated wood to make cooling tower frames.*fn13 The wood was treated in an on-site cylindrical vessel (retort), using two different solutions. Specifically, from 1969 until 1980, the wood was treated with a solution of chromium, copper, and arsenic ("CCA"). In 1980, BAC-Pritchard stopped using arsenic and instead used a solution of acid, copper, and chromium ("ACC"). BAC-Pritchard ceased treating wood at the site in May 1991 and the facility was closed in early 1994.*fn14

The BAC Defendants acknowledge that elevated levels of hexavelant chromium and arsenic were discovered at the BAC Site as early as 1986. That same year, BAC Defendants hired an environmental consultant to investigate and implement a number of remedial measures associated with contamination at the Site. The retained consultant found elevated levels of hexavelant chromium and arsenic in the soil at the BAC Site. Subsequent consultants found hexavelant chromium and arsenic in groundwater beneath the Site and in a stormwater pond located on the southeastern portion of the Site.*fn15

In 1991, IT Corporation, a remediation consultant hired by Merck and Amsted, completed a "clean closure" of the storm water pond. The closure involved excavating contaminated soil from the pond and disposing of it at a landfill under the supervision of the California Department of Toxic Substances Control ("DTSC"). In 1993 and 1994, IT Corp., under the supervision of the Regional Water Quality Control Board ("RWQCB"), installed a pump-and-treat groundwater remediation system to control migration of contaminants beneath and off of the Site and to remove hexavelant chromium and arsenic from groundwater. IT Corp. continued to expand and modify the groundwater treatment system through 2005.

In 1994, as part of the cleanup efforts, IT Corp. prepared a health risk assessment for the BAC Site. According to BAC Defendants, the health risk assessment employed "conservative exposure assumptions" to protect public health and was premised on the fact that no further remediation would take place. Based on these assumptions, IT Corp. determined that contamination at the Site created a cancer risk of two in one million (ratio of 2:1,000,000). The BAC Defendants assert that the DTSC employs a ratio of one in one million (1:1,000,000) to determine whether additional remediation should be performed.*fn16

IT Corp.'s risk assessment did not evaluate the risk posed by the Site in the past (pre-1994), but looked prospectively at the future risk the Site might create if no further remediation was performed. IT Corp.'s risk assessment determined that if soils in the area of the former pressure-treating system were excavated or capped, that would "effectively eliminate the exposure pathways (and subsequent risk)." In 1996, IT Corp. completed excavation of contaminated soil from the area of the former pressure-treating system and installed a four-inch thick asphalt cap over the entire area. The BAC Defendants maintain that the excavation and cap "effectively eliminated the risks identified in the 1994 risk assessment."

Additional remediation at the BAC Site was performed in the mid to late-2000's by Arcadis, Inc., an environmental consulting firm to the BAC Defendants, which was paid $17 million to complete the cleanup of the BAC Site. This included excavation of the contaminated soil beneath the asphalt cap installed in 1996. Once the soil was removed, Arcadis re-paved the exposed soil. Arcadis also treated the groundwater with methanol to convert the hexavelant chromium to the more benign trivalent chromium. T h e groundwater treatment is expected to be completed within a few years, at which point the BAC Site will be monitored by the RWQCB until its final closure.

BAC Defendants assert that they have spent approximately $39 million remediating the BAC Site.

B. RWQCB Involvement - 2007

In 2007, the RWQCB announced the availability for public review of a revised cleanup plan for the BAC Site.*fn17 According to the BAC Defendants, the RWQCB solicited comments from the community and held an informational meeting to discuss the status of the BAC Site remediation. Following the public comment period, in May 2007, the RWQCB published a "fact sheet" regarding remediation of the Site, which purportedly expressed the RWQCB's opinion that contaminants "posed no health risk to residents in the vicinity of the Site." The BAC Defendants assert that the RWQCB's "fact sheet" expressed several additional opinions re: the BAC Site:

1. Groundwater supply wells in the vicinity of the Site have been tested and have not been impacted facility; by the pollution associated with the former BAC

2. Impacted groundwater is not being used for drinking water supply; and

3. The Site is currently not a threat to public health.

(Doc. 677-2 at 7:4-7:7.)

C. 2009 RWQCB Briefing to Senator Dianne Feinstein On January 15, 2009, the RWQCB provided a "briefing paper" on the BAC Site in response to an inquiry by Senator Diane Feinstein. (Doc. 725-4.) The brief "provide[d] a description of the environmental conditions at the site, as well as a summary of the regulatory actions and cleanup responses taken at the site to address hexavalent chromium contamination." (Id.) In the brief, the RWQCB summarized its regulatory involvement, which commenced in 1987, and concluded that "[b]ased upon a thorough review of all of the data currently in the Central Valley Water Board's files, Board staff believe that the public is not being exposed to harmful levels of hazardous substances originating from the BAC site."*fn18

Key details of the RWQCB's briefing are summarized as follows:

* In 1989, the Board determined that sediments in a storm water pond at the BAC site were contaminated with hexavalent chromium. The Board required the BAC Defendants to excavate the pond and further indicates that the BAC Defendants' remedial actions remediate the pond area. Storm water monitoring were effective in reducing total chromium levels in the storm water that was discharged from the site to drinking water of 50 ppb. below California's MCL for total chromium in

* In 1992, the U.S. EPA conducted an investigation to the federal Superfund law ("CERCLA"). Based on its determine if the site warranted actions pursuant to remedial action under CERCLA was required because it evaluation, the EPA recommended that no further found no hazardous substances were detected in designated water intakes or fisheries within 15 drinking water wells or private wells and no Defendants' cleanup activities through public miles. RWQCB notified residents of the BAC notices and a fact sheet. * In 1993, under the regulatory oversight of the was installed. The RWQCB, a groundwater monitoring extraction system 1994 and was regulated pursuant to a permit issued system commenced operations in active in January 2009 and has extracted and treated by the Central Valley Water Board. The system was 5,400 pounds of hexavelant chromium from that water. over 2,200 gallons of water. It has removed over * Merck installed a network of 65 monitoring wells that are used to measure the extent of hexavelant chromium review, conducted by pollution in the groundwater. A thorough Board staff, of the sampling and analyses results form the monitoring well site has not impacted drinking water supply wells in network has determined that pollution from the BAC the vicinity of the BAC site. Testing of the water levels are consistent with background levels for the supply wells indicate that hexavelant chromium area.*fn19

* In 2000, RWQCB staff reviewed and concurred with the BAC Defendants' reports, which indicated that no originating from the BAC site. domestic supply wells were impacted by pollution * RWQCB staff believes storm water discharges from the site since the cleanup of the pond occurred in 1991 the public of hazardous contaminants because: (1) do not present a significant risk for exposure to wood significant treating sources operations of hexavelant ceased chromium in 1991; to have (2) all [and] been the are site;not(3)exposed the soils and sediment in storm water edrainage liminatedfrom hexavelant storm water chromium pond havethat beenwere excavated and disposed contaminated with consistently been below the drinking water standard off site; (4)total chromium concentrations have for total chromium. (Doc. 725-4 at pgs. 2-3.)

The RWQCB's briefing contained a detailed review of the groundwater pollution and cleanup at the BAC Site: the ground surface. Hexavalent chromium has seeped Groundwater at the site is located about 40 feet below area of release with the flow of the groundwater, which into the groundwater, which has migrated away from the is generally to the north. Seasonal migration of contamination to south, beneath a small portion of the Beachwood neighborhood has also occurred [...] regions of the groundwater due to the occurrence of a The contamination has remained confined to the upper clay layer at about 90 to 100 feet below the ground surface. The clay layer has helped to prevent the migration of as the drinking water supply for the local community. contaminants to deeper levels that serve The two nearby drinking water supply wells owned by the Meadowbrook Water Company, which provided water to the groundwater zones. The closest well to the BAC site, Beachwood neighborhood, take water from deeper MWC-4, draws water from a depth 210 feet below the ground surface and is below the clay layer. To ensure water supply, the well is sealed with cement grout to shallow groundwater is not pumped into the drinking MWC-2, takes it water from more than 140 feet below the 200 feet below ground surface. A second supply well, ground, but the well is older and the depth of the seal against shallow groundwater entering the well is unknown. MWC-2 is no longer in service. Monitoring and the two supply wells indicate that the plume has wells emplaced between the hexavalent chromium plume not reached the location of the supply wells in groundwater situated above and below the clay layer.

been tested a number of time and hexavalent chromium The community's drinking wells, MWC-2 and MWC-4, have levels in the wells are within the expected background concentration range for hexavalent chromium.

(Id. at pgs. 7-8.)

The RWQCB attached a table summary of water supply well data for hexavalent chromium from public water supply systems near the Beachwood neighborhood, specifically, Meadowbrook Water Company, the City of Atwater and Winton Water District.*fn20 All of the Meadowbrook wells tested within background levels, including MWC-2 and MWC-4. The RWQCB noted: "For comparison purposes, a number of supply wells for the City of Los Banos, located approximately 25 miles southwest of the site, contain higher levels of hexavalent chromium [than the three closest public water supply systems]."

In its "closing observations," the RWQCB stated that "the public is not currently being exposed to harmful substances originating from the BAC Site," and that the cleanup actions "appear reasonable under the circumstances and the cleanup is proceeding in a satisfactory manner." (Id. at pg. 12.)

D. Plaintiffs' Response to BAC Site History/Remediation Plaintiffs do not specifically dispute the BAC Defendants' recitation of the BAC Site history, including the remediation and RWQCB involvement, rather they take issue with the testing data used to support the BAC Defendants' motions. In particular, Plaintiffs argue that the data from the monitoring wells and MWC-2 Well is unreliable and/or inaccurate for the following reasons, among others: (1) the monitoring wells are too shallow; (2) the use of "selective" and/or "interval sampling"; and (3) the "honor system" employed by the Meadowbrook Water District lacks the necessary formalities to assure accurate records. Based on these factors, Plaintiffs' groundwater modeler, Mr. Douglas Bartlett, allegedly excluded portions of the sampling data from his modeling and analyses. The exclusion, if any, of the MWC-2 and monitoring well testing data is heavily disputed among the parties and forms the basis for BAC Defendants' motion to exclude Bartlett's expert testimony and model.

Plaintiffs also allege that several public entities, including the RWCQB and Defendants Meadowbrook Water District, Merced Irrigation District, and Merced County conspired with the BAC Defendants to: avoid collecting data from the MWC-2 Well, hide documents from third parties, and conceal the true danger/risk of the contaminants at or near the BAC Site. In particular, Plaintiffs contend that the BAC Defendants "conceal[ed] from the Regional Board [RWCQB] and plaintiffs [] the Arcadis groundwater modeling findings concerning the impact of MWC-2 on the contaminated plume." Plaintiffs further allege: "The draft report addressing [Arcadis'] model which was to be submitted to the Regional Board in December of 2007, was altered by Merck by deleting references to the findings of the model and by deleting a graphic illustration of contaminants flowing from the BAC directly into MWC-2."


On March 8, 2007, Plaintiffs commenced this civil action against the current public entity defendants, alleging property damage caused by the April 2006 flood. (Doc. 1.) On September 13, 2007, in the second amended complaint, Plaintiffs named Merck & Co., Inc., Amsted Industries, Inc., Baltimore Aircoil Company, and Track Four, Inc. as Defendants in this action. (Doc. 35.) The operative complaint, the eighth amended complaint, was filed by Plaintiffs on March 26, 2010. (Doc. 633.) The eighth amended complaint alleges ten claims against the BAC Defendants: (1) violation of 42 U.S.C. 6972(a)(1) [RCRA]; (2) violation of 42 U.S.C. 6972(a)(1)(b) [RCRA]; violation of 33 U.S.C. 1311(a) [CWA]; (4) violation of 33 U.S.C. 1342(a) and (b) [CWA]; (5) negligence; (6) trespass; (7) nuisance; (8) wrongful death; (9) fraud and deceit; and (10) civil conspiracy.

On March 23, 2009, BAC Defendants filed a "Motion for Case Management Order Re: Exposure" to "compel plaintiffs to make a prima facie showing of exposure." (Doc. 355.) The motion was denied on July 6, 2009, however, on August 12, 2009, the Court established a multi-phase trial plan in which case-wide exposure issues were to be tried first ("Phase 1"), before general medical causation ("Phase 2") and plaintiff-specific exposure and causation ("Phase 3"). The August 12, 2009 "Order Modifying Scheduling Conference Order" provides, in relevant part:

Discovery and expert disclosures shall be conducted in exposure; that is, whether contaminants from the phases. Phase 1 shall focus on the issue of general the April 2006 Flood have ever reached any location former [] BAC Site, Franklin County Water District or where plaintiffs could have been exposed to them, and if so, when such contaminants arrived, how such were present, and at what levels they were present. contaminants arrived at the location, how long they (Doc. 540 at 1:14-1:28.)

On June 1, 2010, BAC Defendants moved for partial summary judgment on Plaintiffs' state law tort claims for personal injury and property damages, i.e., Plaintiffs' claims for negligence (Claim X), trespass (Claim XII), nuisance (Claim XIII), and wrongful death (Claim XIV).*fn21 (Doc. 677.) According to Defendants, Plaintiffs have failed to produce evidence sufficient to show that any plaintiff was exposed to contaminants allegedly released from the former BAC Site located in Merced, California. BAC Defendants argue that since there is no contamination evidence, there is no genuine issue of material fact on the threshold issue of causation.

In support of their motion, BAC Defendants submit: (1) a Memorandum of Points and Authorities ("Memorandum"); (2) a Statement of Undisputed Facts in Support of its Motion; (3) the declarations of attorney R. Morgan Gilhuly and experts Scott Fendorf, Daniel B. Stephens, John L. Wilson, and Paolo Zannetti; and (4) separate motions to exclude the testimony of Plaintiffs' groundwater expert, Douglas Bartlett, and air expert, Camille Sears.

Plaintiffs opposed the motion on July 1, 2010, submitting over 3,000 pages of documentation and 168 exhibits.*fn22 Plaintiffs oppose summary judgment on grounds that they have "substantial evidence" supporting their contention that "contaminants from the BAC facility have historically migrated from the [BAC] facility via groundwater, surface water and air pathways to locations were exposed to them and at levels which could cause harm." In particular, Plaintiffs argue that Sears and Bartlett's expert testimony is admissible and creates "competing expert opinions as to the migration of the contaminants from the BAC facility." According to Plaintiffs, Sears and Bartlett's expert opinions, by themselves, are sufficient to withstand a Rule 56 challenge.*fn23

BAC Defendants filed their reply briefs on August 13, 2010.*fn24 (Docs. 834 & 835.)


Summary judgment/adjudication is appropriate when "the pleadings, the discovery and disclosure materials on file, and any affidavits show that there is no genuine issue as to any material fact and that the movant is entitled to judgment as a matter of law." Fed. R. Civ. P. 56(c). The movant "always bears the initial responsibility of informing the district court of the basis for its motion, and identifying those portions of the pleadings, depositions, answers to interrogatories, and admissions on file, together with the affidavits, if any, which it believes demonstrate the absence of a genuine issue of material fact." Celotex Corp. v. Catrett, 477 U.S. 317, 323, 106 S. Ct. 2548, 91 L. Ed. 2d 265 (1986) (internal quotation marks omitted).

Where the movant will have the burden of proof on an issue at trial, it must "affirmatively demonstrate that no reasonable trier of fact could find other than for the moving party." Soremekun v. Thrifty Payless, Inc., 509 F.3d 978, 984 (9th Cir. 2007). With respect to an issue as to which the non-moving party will have the burden of proof, the movant "can prevail merely by pointing out that there is an absence of evidence to support the nonmoving party's case." Soremekun, 509 F.3d at 984.

When a motion for summary judgment is properly made and supported, the non-movant cannot defeat the motion by resting upon the allegations or denials of its own pleading, rather the "non-moving party must set forth, by affidavit or as otherwise provided in Rule 56, 'specific facts showing that there is a genuine issue for trial.'" Soremekun, 509 F.3d at 984. (quoting Anderson v. Liberty Lobby, Inc., 477 U.S. 242, 250, 106 S. Ct. 2505, 91 L. Ed. 2d 202 (1986)). "A non-movant's bald assertions or a mere scintilla of evidence in his favor are both insufficient to withstand summary judgment." FTC v. Stefanchik, 559 F.3d 924, 929 (9th Cir. 2009). "[A] non-movant must show a genuine issue of material fact by presenting affirmative evidence from which a jury could find in his favor." Id. (emphasis in original). "[S]ummary judgment will not lie if [a] dispute about a material fact is 'genuine,' that is, if the evidence is such that a reasonable jury could return a verdict for the nonmoving party." Anderson, 477 U.S. at 248. In determining whether a genuine dispute exists, a district court does not make credibility determinations; rather, the "evidence of the non-movant is to be believed, and all justifiable inferences are to be drawn in his favor." Id. at 255.


A. Introduction

Defendants move for summary judgment on Plaintiffs' negligence, trespass, nuisance, and wrongful death causes of action. Defendants' claim there is no evidence of exposure via any pathway, i.e., groundwater, private domestic wells, surface water, air, or soil. Plaintiffs oppose each facet of Defendants' motion, arguing that their expert evidence clearly shows that "contaminants from the BAC have historically migrated from the facility via groundwater, surface water, and air pathways to locations were plaintiffs were exposed to them and at levels which could cause harm." (Doc. 792 at 1:6-1:9.)

The substance of the parties' briefing, more than 5,000 pages of argument and expert/scientific reports, focuses on two pathways, groundwater and air. As to these pathways, Plaintiffs support their Phase 1 exposure burden with the testimony of Douglas Bartlett, groundwater hydrologist (groundwater modeler), and Camille Sears, meteorologist (air modeler). Defendants move to exclude these expert opinions and testimony pursuant to Federal Rule of Evidence 702 and two United States Supreme Court cases, Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579 and Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999). In particular, Defendants challenge Bartlett and Sears' expert testimony on grounds that it cannot pass Daubert's "gatekeeping" requirement.

B. Daubert Legal Standard

Rule 702 governs the admissibility of expert testimony. Pursuant to Rule 702, a witness qualified as an expert in "scientific ... knowledge" may testify thereto if: "(1) the testimony is based upon sufficient facts or data; (2) the testimony is the product of reliable principles and methods; and (3) the witness has applied the principles and methods to the facts of the case." Fed. R. Evid. 702.

The trial court acts as a gatekeeper to the admission of expert scientific testimony under Rule 702. Daubert, 509 U.S. at 579-580. The court must conduct a preliminary assessment to "ensure that any and all scientific testimony or evidence admitted is not only relevant but reliable." Id. at 589. This two-step assessment requires consideration of whether (1) the reasoning or methodology underlying the testimony is scientifically valid (the reliability prong); and (2) whether the reasoning or methodology properly can be applied to the facts in issue (the relevancy prong). Id. at 592-93; Kennedy v. Collagen Corp., 161 F.3d 1226, 1228 (9th Cir. 1998).

Reliable testimony must be grounded in the methods and procedures of science and signify something beyond "subjective belief or unsupported speculation." Daubert, 509 U.S. at 590. The inferences or assertions drawn by the expert must be derived by the scientific method. Id. In essence, the court must determine whether the expert's work product amounts to "'good science.'" Daubert v. Merrell Dow Pharms., Inc., 43 F.3d 1311, 1315 (9th Cir. 1995) ("Daubert II") (quoting Daubert, 509 U.S. at 593). In Daubert, the Supreme Court outlined factors relevant to the reliability prong, including: (1) whether the theory can be and has been tested; (2) whether it has been subjected to peer review; (3) the known or potential rate of error; and (4) whether the theory or methodology employed is generally accepted in the relevant scientific community. Daubert, 509 U.S. at 593-94. The Supreme Court emphasized the "flexible" nature of this inquiry. Id. at 594. As later confirmed in Kumho Tire Co. v. Carmichael, 526 U.S. 137 (1999): "Daubert's list of specific factors neither necessarily nor exclusively applies to all experts or in every case. Rather the law grants a district court the same broad latitude when it decides how to determine reliability as [the court] enjoys in respect to its ultimate reliability determination." Id. at 141-42.

The relevancy, or "fit," prong requires that the testimony be "relevant to the task at hand, ... i.e., that it logically advances a material aspect of the proposing party's case." Daubert II, 43 F.3d at 1315 (quoting Daubert, 509 U.S. at 597). Relevancy requires opinions that would assist the trier of fact in reaching a conclusion necessary to the case. See Kennedy, 161 F.3d at 1230.

The Daubert analysis focuses on the principles and methodology underlying an expert's testimony, not on the expert's conclusions. Daubert, 509 U.S. at 595. However, the Supreme Court has cautioned that "conclusions and methodology are not entirely distinct from one another." General Elec. v. Joiner, 522 U.S. 136, 146 (1997).

As such, "[a] court may conclude that there is simply too great an analytical gap between the data and the opinion proffered." Id. Nothing in either Daubert or the Federal Rules of Evidence requires the admission of opinion evidence connected to existing data "only by the ipse dixit of the expert." Id.

C. Pathway # 1 - Air

Plaintiffs allege that soil contaminated with hexavelant chromium and/or arsenic was transported to their homes or properties via wind and other airborne pathways. To satisfy their Phase 1 burden on the air pathway, Plaintiffs submit: (1) the expert testimony of air modeler Camille Sears (air exposure for the years 1969-1993); and (2) a 1994 Risk Assessment completed by IT Corp (air exposure post-1993 years).

Defendants contend that summary judgment is appropriate with respect to any air pathway because Plaintiffs' expert's testimony is inadmissible under Daubert. Specifically, Defendants move to exclude Ms. Sears' testimony on grounds that: (1) she is not qualified to perform soil calculations; (2) her entire emission scenario is flawed and lacks scientific reliability; and (3) her input parameters are scientifically unsound. As to the Risk Assessment, Defendants assert that it has no evidentiary value because "it was based on a hypothetical scenario that never occurred , and it does not purport to accurately calculate actual exposure or risks." (Doc. 677-2 at 23:18-23:19.) To support their Daubert motion, Defendants rely on the declaration and testimony of Dr. Paulo Zanetti, an air modeler, and Dr. Scott Fendorf, a chemist. Both these experts opine that Ms. Sears' model is scientifically unreliable.

Plaintiffs rejoin that Ms. Sears has performed similar soil calculations in modeling air dispersion, her emission scenario is well-accepted in the air modeling community and the dispute over her input parameters bear on the weight of the opinion rather than on its admissibility.

1. Fed. R. Evid. 706

Based on the extent of the dispute between the parties' experts and the complexity of the scientific issues presented by air modeling, the Court retained two independent experts, Chatten Cowherd Jr., Ph.D. and Richard Countess, Ph.D., under Fed. R. Evid. 706, to assist in the understanding and analyzing the air pathway dispute.*fn25 Drs. Countess and Cowherd prepared a joint expert report, submitted on November 22, 2010. (Doc. 942.) The joint independent expert report and the opinions contained therein are discussed in the context of Defendants' criticisms of the air model.

2. Supplemental Briefing & Fed. R. Evid. 706 Experts The parties filed supplement briefing concerning the air expert reports on November 29, 2010. The supplemental arguments mirror those advanced in the parties' earlier briefing, however, Plaintiffs reiterate that "the FRE 706 reports serve only to confirm the grave concerns plaintiffs have repeatedly expressed to this Court related to these Daubert proceedings." Plaintiffs contend that the Court "may be tempted to act as a trier of fact by weighing the relative strengths and weaknesses of factual and scientific assumptions made by the experts."*fn26 They further assert that the air model disagreements "go to the weight of their opinions, and not their admissibility."

Defendants rejoin that the 706 expert reports "confirm[] that Plaintiffs' groundwater and air models contain serious methodological flaws, including faulty assumptions unsupported by science or facts, and are not reliable." Responding to Plaintiffs' "weight" arguments, Defendants assert that if Ms. Sears' expert report is either unreliable or irrelevant, it is inadmissible.*fn27

An inadmissible report cannot create a disputed issue of fact. BAC Defendants also include a string citation to a number of federal cases holding that, under Daubert, an expert opinion cannot be "based on assumptions of fact without evidentiary support, or on speculative or conjectural factors."

3. Testimony/Model of Camille Sears (1969-1993) Plaintiffs designated Sears as an air pathways expert who will opine on whether Plaintiffs' homes were exposed to significantly elevated air concentrations of hexavalent chromium and arsenic.*fn28

Sears' declaration specifies she has worked in the air quality field since January 1982, following her graduation from the University of California at Davis (M.S. and B.S. degrees in atmospheric science). Prior to forming her own consulting firm in 1992, Sears worked as a private air consultant/scientist (Dames & Moore, URS Consultants) and Air Toxics Program Coordinator (Santa Barbara Air Pollution Control District). Sears has been a testifying expert for twenty years, since 1990, and provided air modeling testimony in California Dept. of Toxic Substances Control v. Interstate Non-Ferrous Corp., No. 97-CV-5016-OWW-LJO, an environmental contamination case involving, among other things, the alleged air dispersion of dioxin-containing ash released from incendiary operations at a smelting site in Mojave, California.

According to her expert reports, declarations, and testimony, Sears' followed a three-step process. First, she calculated air concentrations and surface deposition of hexavelant chromium and arsenic resulting from the BAC site based on "widely-accepted air dispersion modeling techniques." Second, she input these calculations into an air flow model endorsed by the U.S. Environmental Protection Agency called AERMOD to determine if Beachwood residents were exposed to particulates from fugitive dust emissions sources at the former BAC site. Third, she provided opinions re: whether, from 1969 to 1993, areas surrounding the BAC facility were exposed to elevated air concentrations of arsenic and hexavelant chromium.

Sears built her model by extrapolating data from chromium at the BAC site, in a treating solution that was released to the ground at the retort area where it entered the soil, and that this exposed solution in and on the soil was later disturbed by forklifts driving on the site. She offered the following opinions of exposures caused by the BAC facility wood storage area emissions:

* During the period 1969 through 1993, areas significantly elevated air concentrations of surrounding the BAC facility were exposed to hexavalent chromium;

* During 1969, and the period 1991 through 1993, areas surrounding the BAC facility were exposed to elevated air concentrations of through 1990; hexavalent chromium, but not as high as 1970

* During the period 1969 through 1983, areas surrounding the BAC facility were exposed to significantly elevated air concentrations of arsenic;

* During 1969, and the period 1981 through 1983, exposed to elevated air concentrations of areas surrounding the BAC facility were arsenic, but not as high as 1970 through 1980;

* During the period 1969 through 1983, areas increased arsenic surface deposition levels; surrounding the BAC facility were exposed to

* During the period 1969 through 1993, areas surrounding the BAC facility were exposed to deposition levels. increased hexavalent chromium surface (Doc. 781 at 5:21-6:9.)

Defendants move to exclude these opinions because her testimony rests on a number of unsupported assumptions about the chemical and physical properties of soils at the Site during the relevant time period (1969-1993). According to Defendants, Sears is unqualified to make these assumptions because she "is an atmospheric scientist and meteorologist, not an expert in chemistry, geology, geochemistry, or soil science." In addition, as part of her calculation of fugitive emissions, Sears allegedly employed an improper EPA emission technique, namely the paved road emission scenario (AP-42, § 13.2.1). The flawed assumptions, enumerated below, relate solely to Sears' "emission rate" calculations:

1. Valence - Sears assumes that all of the chromium that dropped from treated wood at the BAC site was hexavalent chromium;

2. Particle Size - She assumes the contaminated dust was comprised of particles that were less than 10 microns in diameter, making them small enough to blow off the site; and

3. Accumulation - She assumes that one year's worth of drippage accumulated and remained on the surface of the site, in the form of dust that is 90 percent pure (900,000 parts per million) chromium and arsenic.

Defendants contend that these assumptions are demonstrably false and Sears does not have the expertise to make them. To support their Daubert motion, Defendants rely on the declaration and testimony of Dr. Paulo Zanetti, an air modeler, and Dr. Scott Fendorf, a chemist. Dr. Zanetti disputes Sears' use of the EPA's "paved road" emission scenario and, critically, the assumption that drippage would accumulate and remain on the surface of the wood storage area in the form of dust at a concentration of 900,000 parts per million. Dr. Fendorf opines that chromium does not drip off only in hexavalent state and, assuming it did, the chromium particles would be at least 100, not 10, microns in size.

Sears responds first to Defendants' claims that she is unqualified to calculate fugitive dust emissions from a wood processing facility:

dust emissions from a wood treating facility, the While this is the first time I have calculated fugitive principles involved are no different than any other have calculated air emissions of hexavalent chromium paved surface fugitive dust source. Furthermore, I dozens of times - from cooling towers, annealing coatings (including primers and pigmented - paints), operations, chrome plating and anodizing, surface welding operations and cold fire combustion. I also from combustion sources, fugitive dust and mining have experience calculating air emissions of arsenic -activities.

(Doc. 785 at ¶ 15.)

On October 7, 2010, the second day of Daubert hearings, Sears testified that while she lacks formal "soil science" training, she has calculated air emissions in a number of environmental contamination cases and teaches a class in chemistry:

First of all, I heard [defense counsel] say that I had no education in chemistry or geology or soil science. That's number of chemistry courses and I've been involved in a -- that's never anything that I've said. I have taken a chemistry to air toxic students through the UCSB number of soil analyses over the years. I've taught extension as part of my air toxics class. I never said it's correct for [defense counsel] to say so.

I had no education in chemistry. And I don't believe Over the last 30 years, which is the time that I've been use of chemistry on a weekly basis. It's part of the job doing these types of analyses, I've been involved in the geologist, soil scientist or geochemist to calculate air experience. You don't need to be a chemist or a emissions from basically soil releases or surface releases of dust. expert on this issue, I don't believe has ever calculated On the contrary, Dr. Fendorf, who they offer as their air emissions, or at least I did not see any of his emissions. qualifications stating that he has ever calculated air (RT, Oct. 7, 2010, 257:7-257:25.)

Ms. Sears detailed her experience calculating fugitive air emissions during counsel's direct examination on October 13, 2010. Ms. Sears' air emission experience, which is quite extensive and includes review of industrial sites and hexavalent chromium, rules out any characterization of her as "unqualified" in the field of calculating air emissions:

Q. emissions?

Ms. Sears, are you qualified to calculate air

A. Yes, I believe so.

Q. And why do you feel that you're qualified to do that?

A. Well, first, I want to correct -- or give my viewpoint to calculate air emissions. We heard testimony last on the issue of whether a meteorologist is qualified week that Ms. Sears is a meteorologist and atmospheric scientist and therefore she's not qualified to First of all, meteorologists, atmospheric scientists, calculate air emissions. I believe that's untrue. we need to take all the chemistry, all the physics that basically any engineer would take. And basically calculating air emissions in 1983. I was hired by the the rest of it is real world experience. I started Santa Barbara county air pollution control district as emissions, not only for permitting purpose, but also an air pollution engineer. And my job was to calculate for fee calculations. Our district became a fee based entity, which the fees were generated by the amount of emissions that companies emitted.

And during that time, when I was at the air pollution control district, not only did I calculate emissions for a number of different sources, I also had to or EETs for many sources for which we never calculated develop what we called emission estimating techniques, emissions before.

Q. Let me ask you just on this subject. What types of emissions did you calculate when you were with the Santa Barbara County Air Pollution Control District?

A. I was just about to answer that. Thanks. The types of emissions I would calculate were generally by the --early '80s, the only thing we dealt with would have I'll do it by type of pollutant. Originally in the been called c pollutants for riteria air which there were pollutants. And those are standards. For example, nitrogen dioxide, sulphur ambient air quality dioxide, carbon monoxide, lead and particulate matter were the ones where we would calculate emissions.

volatile organic compounds as well. Later in the '80s, And for ozone, we would calculate emissions of when air toxics, we also called non-criteria pollutants became the focus of regulation, we had to calculate air emissions of essentially all the toxic the district. And those would include oil and gas chemicals that you can think of from every source in processing facilities, excuse me, medical device manufacturers, diatomaceous earth mining facilities, operations. There were no end to the different types we had Casmalia class one landfill. We had mining of sources that we had There's several hundred different facilities I was to calculate emissions from. responsible for calculating air emissions.

Q. And give us an example as to how you did calculate the emissions at that time.

A. Well, I -- I could think of a lot of them. However, the type of emissions that -- the type of sources that we would generally deal with for air toxics, you might had offshore and on shore components, stationary and think of as an oil and gas processing facility. And we mobile sources. So we had to identify all the emission quantify them using emission calculation methods. sources for all the different pollutants and then Sometimes we did source testing. And other times, like I said, we have to use what we call emission air toxics, none of these emission factors existed. We factors. And again, for many of these sources, for had to develop them. And I was on the committee for the State of California, the criterion guidelines emission estimating techniques or EETs for air toxics. regulation committee, which established a number of

Q. And how many cases have you testified in either a courtroom like this or in state court or an administrative hearing, wherein you have rendered emissions, Ms. Sears? opinions and testimony on the calculation of air

A. About 15 cases. And I outlined them in my opposition where I've actually calculated emissions that went declaration. So about 15 cases where I testified and into my model.

Q. And what experience do you have in calculating air emissions of hexavalent chromium?

A. Over the years, probably starting in the late '80s, I calculated air emissions of hexavalent chromium dozens of times from cooling towers, where zinc chromate was added as an -- vis-a-vis an anti-corrosion compound. anodizing and chrome plating operations, both hard Calculated hexavalent chromium emissions from chrome chrome and soft chrome. And also from sparging, which is air injection into chrome plating operations.

Q. here, what experience do you have in evaluating the Now, in terms of the central valley of California impact of hexavalent chromium in the air here in the central valley of California? Which is where the BAC plant is located.

A. Okay.

Q. Former BAC plant.

A. I'll answer that. But I also want to say I've also surface coating operations, such as spray painting and calculated hex chrome emissions from a number of aircraft refurbishing and that type of thing. Certain coatings, zinc chromate, strontium chromate, lead chromate have hexavalent chromium in the formulation. Now, as far as the Central Valley goes, I have calculated emissions from cooling towers. This was from a case where the emissions were in the past. And emissions. And then I modeled these emissions and we calculated -- or I calculated hexavalent chrome calculated the air concentrations. And then we were also involved in looking at the background levels of hexavalent chromium in the central valley, basically I've had quite a bit of experience looking at the data in the '90s. Because that's when we had data. And so from the hexavalent chrome in the air from Stockton, Resources Board was collecting this data in the 1990s. Modesto, Fresno, Bakersfield, the site where the Air

Q. What experience -- there was some mention last week by background in regard to the chemistry of air [defense counsel] about your background or lack of pollutants. Do you remember that testimony?

A. I do.

Q. What is your experience in regard to the chemistry of air pollutants, Ms. Sears?

A. Well, again, I want to say that, again, I'm a meteorologist, and I would never say I'm a chemist, but I would never say I don't have any education in it, though, is on the job training in the last 30 chemistry. I do. And -- but I -- and again, a lot of years since I graduated with a masters from UC Davis. And essentially what you have to think of is that when you need to know something about the chemistry of you're looking at air toxics, toxic air pollutants, these chemicals. You know, chlorinated alkanes, different things come into play as well as the chlorinated alkines, valence of metals, all these formation. All these are issues that we have to deal reactivity of volatile organic compounds in ozone with consistently in the air pollution field. And so the chemistry, but not having to be a chemist to do it's a matter of needing to know certain details of so.

Q. So let me ask this more specifically. What is your subject of understanding the chemistry of air education, training and background in regard to the pollutants?

A. a chemist, but I've t

Well, I've taken the basic, you know, again, I'm not sophomore chemistry classes. And essentially I was an aken the basic freshman, atmospheric physicist in -- at Davis, that was my Davis. And so we dealt a lot with the issues of specialty. I wasn't an air modeling student at UC would deal with individual compounds as well. And electricity, magnetism, electromagnetic issues, that again, after I graduated and became working in the air toxics field, I had to ref know, go back into dealing withal canes, al keens, al resh my memory and, you all these kinds, air mat I can hydrocarbons and so forth and how I'm not a chemist, but I'm compounds relate to each other. So again, chemistry either. not a completely ignorant

Q. In the opinions that you have rendered in other cases and in other courts, subject of chemistry in regard to air pollutants? have your opinions included the

A. Yes. I can give you some examples.

Q. Why don't you do that.

A. One case that I was working on, it was a federal court dealt with soil case. It was Akee versus Dow, it was in Hawaii. It fumigants. And the soil fumigants from 1946 to -- 1946 to 2001. I calculated air were applied to pineapple fields on the island of Oahu ethylene emissions from volatilization of Dibromochloropropane, 1,2-dichloropropane, and epichlorohydrin from 319 dibromide, 1,3-trichloropropene, pineapple fields for 56 years. And, of course, the didn't file any motions to exclude any testimony, they defendants' experts challenged everything I did. They just disagreed with me [....] (RT, Oct. 13, 2010, 560:12-567:4.)

Camille Sears is qualified to offer the testimony about how to calculate fugitive air emissions from a former wood-treatment facility. She has substantial experience in the air emission field, having calculated air emission rates for over twenty years in and around Northern and Central California. Sears has calculated fugitive air emissions for public and private employers and has experience with industrial sites and a variety of harmful pollutants, including hexavelant chromium. By education and experience, Ms. Sears is qualified to opine on air emissions, analysis and modeling in this case and her calculations can be challenged through cross-examination and presentation of contrary evidence. See Robinson v. GEICO General Ins. Co., 447 F.3d 1096, 1106 (8th Cir. 2006)("Gaps in an expert witness's qualifications or knowledge generally go to the weight of the witness's testimony, not its admissibility.").

Defendants take an overly-narrow view of the degree of expertise necessary to calculate fugitive air emissions in the context of air modeling. An air modeler, who is also an experienced atmospheric scientist and meteorologist, does not need to have a "sub-specialty" or advanced degree in chemistry or soil science before that person has sufficient qualifications to perform air emissions. Defendants cite no authority for such a proposition. Rather, Rule 702 only requires that an expert possess "knowledge, skill, experience, training, or education" sufficient to "assist" the trier of fact, which is "satisfied where expert testimony advances the trier of fact's understanding to any degree." See Ms.Lauria v. Nat'l R.R. Passenger Corp., 145 F.3d 593, 598 (3rd Cir. 1998) (holding trial court abused its discretion by excluding testimony simply because the trial court did not deem proposed expert to be the best qualified or because proposed expert did not have the specialization that the trial court considered most appropriate); see also United States v. Newmont USA Ltd., No. CV-05-020-JLQ, 2007 WL 4856859, at 2 (E.D. Wash Nov. 16, 2007) (in a mining enterprise case, holding that although the expert "is a historian, as opposed to an expert in the specific areas of 'corporate organization' is not disqualifying in this case, as his background appears to provide sufficient expertise upon which his opinions, as a general matter, are based."). Ms. Sears has engaged in the field of air modeling and analysis as a regulator and expert for over twenty years. She has worked on sites that have toxic dust emissions. She satisfies Rule 702's foundational standards and her testimony will assist the trier of fact.*fn29

Defendants next argue that Ms. Sears' entire emission scenario is flawed and lacks scientific reliability. According to Dr. Zanetti, Ms. Sears' flawed methodology begins and ends with her use of the "paved road" or "parking lot" emission scenario, AP-42 § 13.2.1. Dr. Zanetti opines that there is no scientific basis to model the paved portions at the BAC Site because they do not qualify as "roads." Rather, according to Dr. Zanetti, the proper emission scenario in this case is the EPA equation for unpaved surfaces. The selection of AP-42 as an emission scenario was fully developed during defense counsel's direct examination of Dr. Zanetti on October 14, 2010:

A: herself, my understanding, she developed this new

In Ms. Sears' scenario, she did all the work by theory, she developed emission rates, she applied the Certainly she has the AERMOD model. She applied the AP-42 equations. equation and to use it. The problem is is this the capability to select an AP-42 correct lacking the mathematical skills to use those methodology? It's not a question of her equations, the question is is the equation or the methodology appropriate [...] understand, my reading of Ms. Sears' work in this I tried to summarize in a way that is easy to case. And in particular, the emission scenario. So brief description. there are seven points. And I can start giving a

Q. Okay. Before you do that, if you would, please, "emission scenario." explain to us all what you mean by the phrase

A. An air pollution model is a computer program that and the meteorology. requires basically two main inputs. The emissions

Q. The emission?

A. The meteorology, like the wind speed, the wind direction, the temperature. So these are the two main will be the conce inputs. Emission and meteorology. And the results ntration data in the community. So collect. There the meteorological data are generally easy to States providing meteorological data, like wind are airports all over the United generally this is not a big speed, wind direction that we can collect easily. So task. But the emission enormous consequences in air pollution modeling calculation is often a major task and that has application because if the emissions are incorrect, the concentration will be incorrect in the same proportional amount.

Q. Okay. So emission scenario refers in the BAC case to what?

A. from paved surface in the wood storage area. So task In Ms. Sears' theory, she is considering emissions number one is my the period '69 to 1993, she assumes that contaminated description of her work, that for arsenic and chromium 6, is dripping from the treated liquid, liquid contaminated with heavy metals, drip over -- or this paved surface of the wood wood in the wood storage area and this liquid will storage area. That's step number one. (RT, Oct. 14, 2010, 703:8-707:2.)

Dr. Zanetti argued that there was insufficient "road traffic" at the wood treatment area to support Ms. Sears' selection of the emission scenario for paved roads. He also argued that AP-42 explicitly states that the AP-42 formula should not be applied to "stop and go" traffic:

A: And she is using the AP formulas for road traffic.

And this formula has been used many, many times [...] so this formula has been used by hundreds of times all over the world. It's a simple formula.

Q. But it's used for, you said, road traffic?

A. Road traffic. And my comment is that, first of all, I is no road. look at the picture of the wood storage area. There

Q. Okay.

A. First of all. Second, there is a picture of, in the a road with traffic. And no forklifts in the traffic, AP-42 document, which I have in my files, and it shows of course. This formula is designed for calculating think I ever seen, and I don't think Ms. Sears has emissions from traffic, not for forklifts. I don't cited one literature study where this formula has been applied to forklifts. And in order to apply to assumption that are inherent in the development of forklifts, you need really to stretch enormously the this formula.

The most important one is the speed. The formulas was developed for ve speed, average, between 10 miles per hour up to 60 hicles that travel with an average miles per hour, if I remember correctly. But 10 is the have an average speed of 10miles per hour. It's stop main one. There is no way you can claim a forklifts and go. It's --Q. Does AP-42 apply to stop and go traffic?

A. applied, the formula should not be applied for stop No. It explicitly say, the formula that Ms. Sears

AP-42 for forklifts. And again, the most important and go traffic. So it is very questionable, the use of thing, there is no literature support for doing that. I haven't found one single study.

(RT, Oct. 14, 2010, 715:15-717:1.)

During counsel's re-direct examination on October 14, 2010, the fourth day of Daubert hearings, Ms. Sears testified that AP-42 is appropriate in these circumstances given the lack of an emission scenario for forklift use at industrial sites:

A: Now, I think it's important process that I used to calculate the air emissions to describe that -- the from the fugitive dust, the treated wood storage called AP 42, which is number 42 in an air pollution area. I used an EPA factor. It's from a document document series prepared by US EPA. And it's a used to calculate air emissions from various types of compilation of emission factors. Which are techniques activities.

And in this case, Section 13.2.1 deals with fugitive technique that can be used to any paved road or dust from paved roads or parking lots. It's a parking lot. There's nothing unique about fugitive dust coming off a paved surface area at a wood treatment plant or a treated wood storage area paved surface. It's the same technique.

And I used that same technique scores and scores and scores of times. I've used it for refineries, I've used it for oil and gas processing facilities, for plants. The list goes on. I've done it scores and steel mills, for quarries, or battery recycling scores of times. And there is a very simple, I think, a very simple determination based on my experience that it would also apply to this facility.

Q. You mean the type of surface from which fugitive dust would be sitting upon and then emitted through some type of activity?

A. surface dust on the surface of the soil. That then Right. What happens is that you have an amount of disruption by vehicular tires, mainly. And the can be released into the air due to mechanical vehicle doesn't vehicle that matters. matter, it's the weight of the

The fact that Ms. Sears used a different algorithm to calculate fugitive air emissions than Dr. Zanetti does not render her unqualified nor does it suggest her emissions scenario is invalid. Rather, based on the current record, her emissions scenario is relevant, admissible, and can be challenged through cross-examination and presentation of contrary evidence. In this Circuit, an expert's decision to use one form of scientific methodology over another goes to the expert's credibility rather than the admissibility of the testimony. See, e.g., United States v. Garcia, 7 F.3d 885, 889-90 (9th Cir. 1993). This is such a case.

In addition, the Fed. R. Evid. 706 air experts, Drs. Countess and Cowherd, agree that there is a scientific basis to use AP-42 as an emission factor equation in this case. The relevant portion of the joint expert report provides, in relevant part:

We believe that Sears has made reasonable scientific judgment in selecting the paved road equation to project associated with applicability problems (low speed, "stop emissions from forklift traffic in the TWSA. The errors and go" motion) are probably small compared with errors analysis as detailed below. If a separate equation were and uncertainties associated with other items in her available for application would be advisable to use it. to stop and go activity, it

(Doc. 942, pg. 12.)

Contrary to Defendants' contentions, the application of the "paved road" emission scenario was within Ms. Sears' realm of expertise as an air modeler and meteorologist. She has selected emission scenarios and calculated fugitive emissions for over twenty years. Ms. Sears has the expertise to use scientific judgment that AP-42 was the most accurate emission scenario for the former-BAC Site. This is especially true given the lack of a scientific algorithm designed explicitly for the types of industrial use and emission estimates required in this case. Dr. Zanetti's contention that only "unpaved surfaces" at the BAC site can be modeled is unreasonable given the 706 experts' contrary opinions. He offers no alternative to his unpaved model, citing only the "lack of scientific literature" to support Ms. Sears' AP-42 emission scenario.*fn30

The review of Sears and Zanetti's expert reports and deposition/hearing testimony, as well as the opinion of the Court's Fed. R. Evid. 706 experts, demonstrate that although the use of AP-42 to calculate fugitive emissions from the wood storage area of the former-BAC Site is sharply disputed, a disagreement over methodology is left to the adversary process and the trier of fact. The methodology here is not comparable to that found unreliable in In re Voluntary Purchasing Groups, Inc. Litigation, 2000 WL 1842779 (N.D. Tex. 2000), a case excluding an air modeler's expert testimony under Rule 702 and Daubert.

Defendants' remaining arguments focus on the total mass calculation and the input parameters of Sears' model, i.e., drippage accumulation, the particle size, valence/purity of the contaminant and silt loading values. However, several of these inputs are functions Dr. Agardy's total mass calculation, which is not challenged and admissible:*fn31

and arsenic at the former BAC wood storage area, I Rather than estimate the amount of hexavalent chromium calculated the amount of elemental material contributing to silt loading (in grams per square meter) based on Dr. Agardy's drippage calculations. Dr. Agardy's [...] [Dr. Agardy's] drippage calculations were calculations are not subject of a motion to exclude conservative because they were limited to the chromium levels found in treated wood storage area soils. These [hexavalent levels could only have result from drippage of the Cr VI subsequently entered the soil. My calculation did not chromium] from treated wood that take into account the amount of contaminants that never entered the soil.

(Doc. 785, C. Sears Decl., at ¶ 50.)

The majority of Dr. Agardy's opinions are proper as they relate to the use of chemicals and chromium at the BAC site. These figures were a basis for Sears' model and are properly supported by Agardy's qualifications and expert reports. However, in his "new" declarations, (Docs. 782 & 955), Agardy opines on subject matter outside of his expertise: chemistry. Agardy is not qualified to opine on the conversion rates between Chromium III and Chromium VI.

A review of his declaration reveals that Agardy simply quotes from several leading chemistry treatises and hornbooks, without establishing his own expertise to do so. Agardy's opinions on the chromium conversion are questionable. He is, however, qualified to opine on the total chromium mass at the former-BAC Site.

The final dispute concerns the scientific reliability of Sears' input parameters: the drippage accumulation; the silt loading values;*fn32 the valence/purity of the contaminant;*fn33 and the particle size (10 microns v. 100 microns). Sears contends that her input parameters conform with well-recognized scientific principles. She asserts that the input parameter calculations are based on her scientific knowledge, experience and familiarity with air modeling, as well as a review and analysis of historical information at the BAC Site, Dr. Agardy's chromium drippage calculations, USEPA air pollution emission factors for paved roads, environmental and wind data from the site, and a review of pictures of the BAC Site and industrial vehicles used at the site. Defendants rejoin that these four input parameters lack scientific reliability and are inadmissible to generate a factual dispute.

Drs. Countess and Cowherd's Fed. R. Evid. 706 expert report provides a starting point to analyze the dispute over the input parameters. The Fed. R. Evid. 706 expert opinions are reproduced below, contrasted with the Daubert testimony of Ms. Sears. The expert report and opinions of Drs. Countess and Cowherd cast considerable doubt on Ms. Sears' silt loading, valence, accumulation and particle size inputs. Under Rule 702 and Daubert, however, the proper analysis is not whether some of the inputs can be questioned, but whether Sears' testimony is relevant and reliable, and whether the methods and principles upon which she has relied in forming her opinion have a sound basis in science. In this case, a comparison of the relevant expert opinions demonstrates a reasonable scientific dispute over input parameters and scientific principles.

First, Drs. Countess and Cowherd's independent expert report characterizes Sears' silt loading value as "seriously flawed":

flawed. There is no prece Sears's assumptions about silt loading are seriously silt loading is comprised almost e dent for assuming that the [hexavelant chromium] and arsenic. Sears should have ntirely of Cr and arsenic pentaoxide as well as (at the very least) based her estimates of silt loading on chromium trioxide particles in the silt size range. deterioration of the asphalt pavement that would produce (Doc. 942, pg. 15.)

On December 2, 2010, on direct examination, Sears explained that her silt loading values comported with "standard modeling practices":*fn34

Q. With respect to the assumptions and the input believe that the technique, the assumptions with respect to silt loading, why do you the assumptions you utilized were in keeping with method you used and generally accepted standards and principles?

A. Again, the silt loading values that I used were based on Dr. Agardy 's drip calculations. Which I believe he performed correctly. And I talked to him about them. There was just no black box that was handed to communication. The generally accepted standard and me the day I ran the model. We had a lot of approach is to use a steady state value. Even when you're modeling short - term air exposures. I've been power plant permit applications, steel plant, pig iron reviewing dozens, like I said, of these coal fired state value. And I'll give another example. plant applications and they all use the same steady I recently was asked by the California Attorney proposition 65 case. The issue was hexavalent General's office to help them review potential chromium and arsenic from fugitive dust at the Lehigh Cement Plant in Cupertino. They wanted to know had filed a 60 day notice of requirements to warn whether they should intervene because some citizens under Proposition 65.

So they asked me to look at it. The producer of this consultant to Merck in other matters in this case. report was a AMEC Geomatrix, which has been a about. They -- even t

And they did the exact same approach that I'm talking site, they didn't measure the silt loading. They hough there was an existing the average for a cement plant. They could have estimated it. They estimated what it would be based on measured it.

But the key point is that they used a steady state value for the life of the 70 years. And that's generally accepted scientific exposure assessment to run standards and practice for silt loading. You don't vary it. To do so would be beyond that, to do so unnecessary standard. Unnecessary because we're would be holding me to basically unprecedented and calculating long-term average emission rates.

(Rough RT, Dec. 2, 2010, 173:14-175:1.)

With respect to the "accumulation" factor the Fed. R. Evid. 706 experts provide, in relevant part:

Sears's assumption of a one-year accumulation period is unreasonable because it assumes that no losses such as runoff from the paved surface due during that period. Because of the solubility of the to rainfall occur contaminants in original form, any precipitation would undoubtedly cause the contamination to wash off the into the soil below the paved surface, so that the paved surface and/or penetrate the thin layer of asphalt equilibrium time would be much shorter, especially during the rainy season. Our review of Merced Municipal Exhibit A-17, Folder Q) indicates that the wettest Airport precipitation records from 1948 to 2006 (Court month with at least 0.01 in. of precipitation. During months are November through April with 5-10 days per this six-month period there are 3-6 days per month with at least 0.1 in. of precipitation, and an average of one The driest months are May through October with an day per month with at least 0.5 in. of precipitation. average of one day per month with at least 0.01 in of precipitation. Thus, we conclude that a more reasonable months for the six-month period May through October, and accumulation period would range from one month to six a maximum of several weeks for the six-month period November through April.

(Doc. 942, pg. 17.)

Although the one-year accumulation rate is allegedly unreasonable, Sears testified at the Daubert hearings that her figure was an "average" and that ...

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