United States Court of Appeals

For the Eighth Circuit

___________________________

No. 18-3357

___________________________

Green Plains Otter Tail, LLC

lllllllllllllllllllllPlaintiff - Appellant

v.

Pro-Environmental, Inc.

lllllllllllllllllllllDefendant - Appellee

 ____________

Appeal from United States District Court

for the District of Minnesota

 ____________

 Submitted: November 12, 2019

Filed: March 20, 2020

____________

Before COLLOTON, WOLLMAN, and BENTON, Circuit Judges.

____________

BENTON, Circuit Judge.

Green Plains Otter Tail, LLC owns and operates an ethanol production facility. 

In 2014, an explosion and fire extensively damaged it. Green Plains sued ProEnvironmental, Inc. for negligence and products liability, alleging defective design

and failure to adequately instruct and warn users. The district court granted summary
judgment to PEI. Green Plains appeals. Having jurisdiction under 28 U.S.C. § 1291,

this court affirms in part, reverses in part, and remands. 

I.

Green Plains produces ethanol in Fergus Falls, Minnesota. Producing ethanol

makes pollutants. These pollutants are burned off in a regenerative thermal oxidizer

(RTO). Dampers control the flow of vapors in and out of the RTO’s chambers. 

These dampers are powered by a hydraulic pump unit (HPU). In an emergency, the

RTO should (1) close to keep unprocessed vapors out and (2) release the vapors

already inside into the atmosphere. Both functions require hydraulic pressure (1) to

close the input damper, and (2) to open the release damper.

 

The HPU has an accumulator that supplies hydraulic fluid for the RTO’s

regular cycles. If a hydraulic pump within the HPU fails, the accumulator should

force its fluid back into the system, moving the dampers to safe positions. In order

to operate, the accumulator must be recharged with nitrogen. 

The HPU’s hydraulic pump is connected to the other parts of the HPU by

couplings. In 2014, a coupling failed, causing a loss of hydraulic pressure to the

HPU. Several alarms sounded. Green Plains’s staff discovered that the dampers did

not move to safe positions. An hour later, an explosion damaged the RTO, other

equipment, and buildings. 

The RTO’s dampers could move to safe positions only if the accumulator was

sufficiently precharged. Post-explosion investigations showed almost no precharge

of the HPU’s accumulator. The HPU manual that PEI gave Green Plains said:

The accumulator is precharged at time of commissioning to

a predetermined pressure with inert nitrogen. A charging

-2-
and gauging assembly should periodically be attached to

the accumulator charge port to check the accumulator

precharge, and should be recharged as needed using only

dry, inert nitrogen. These operations should be performed

with the system off, and all hydraulic pressure relieved

from the system. 

The manual added: “It is suggested that a check be made a week after installation,

and thereafter once a month.” A label on the HPU unit warned, in all capital letters,

that failure to follow directions can cause malfunctions leading to death, personal

injury, and property damage. The label directed users to a website with instructions. 

Green Plains never checked the level of precharge, or recharged the nitrogen, during

the six years between the RTO’s commissioning and the explosion, nor did Green

Plains keep on-site the parts to check the precharge.

Green Plains sued PEI in 2016, alleging negligence and products liability for 

defective design of the RTO, and inadequate warnings of the importance of the

accumulator. The district court granted summary judgment to PEI, ruling that Green

Plains’s lack of maintenance was a superseding cause negating PEI’sliability for any

design defect, and that the design was not unreasonably dangerous. The court also

granted summary judgment on Green Plains’s failure-to-warn claim, stressing the

absence of evidence in the record that employees read the warnings in the manuals. 

Green Plains Otter Tail, LLC v. Pro-Environmental, Inc., 349 F. Supp. 3d 768, 780

(D. Minn. 2018).

Minnesota law governs this diversity action. Lamoureux v. MPSC, Inc., 849

F.3d 737, 739 (8th Cir. 2017). This court reviews de novo the grant of summary

judgment. Thompson v. Hirano Tecseed Co., Ltd., 456 F.3d 805, 808 (8th Cir.

2006). Summary judgment is proper if there are no genuine issues of material fact

and the moving party is entitled to judgment as a matter of law. Fed. R. Civ. P.

56(c). “Where the record taken as a whole could not lead a rational trier of fact to

-3-
find for the nonmoving party, there is no genuine issue for trial.” Torgerson v. City

of Rochester, 643 F.3d 1031, 1042 (8th Cir. 2011) (en banc), citing Matsushita Elec.

Indus. Co. v. Zenith Radio Corp., 475 U.S. 574, 587 (1986). 

II.

Under Minnesota law, a products liability claim for defective design requires:

(1) the product was in a defective condition unreasonably dangerous for its intended

use; (2) the defect existed when it left the manufacturer’s control; and (3) the defect

was the proximate cause of the injury sustained. Adams v. Toyota Motor Corp., 867

F.3d 903, 916-17 (8th Cir. 2017), citing Bilotta v. Kelley Co., 346 N.W.2d 616, 623

n.3 (Minn. 1984). A manufacturer has a duty to design its product to avoid an

unreasonable risk of harm when the product is used as intended or in an unintended

yet reasonably foreseeable manner. Id. at 621. “Whether a product is defective is

generally a question of fact; only where reasonable minds cannot differ does the

question become one of law.” Thompson, 456 F.3d at 809 (applying Minnesota law).

“Minnesota merges negligence and strict liability claimsinto a single products

liability theory, which employs a reasonable-care balancing test to determine whether

a product is defective.” Id. “To determine whether there is enough evidence to

submit the claim to a jury, the court must balance the ‘the likelihood of harm, and the

gravity of harm if it happens, against the burden of the precaution which would be

effective to avoid the harm.’” Young v. Pollock Eng’g Grp., Inc., 428 F.3d 786, 789

(8th Cir. 2005), citing Bilotta, 346 N.W.2d at 621. 

“An important factor in this balancing test isthe availability of a feasible, safer

alternative design.” Id. To demonstrate that the product is unreasonably dangerous,

“the plaintiff ordinarily has the burden of showing the existence of an alternative

design that was safer.” Kallio v. Ford Motor Co., 407 N.W.2d 92, 96 (Minn. 1987). 

-4-
If the manufacturer presents evidence to dispute the product is unreasonably

dangerous “the trier of fact will resolve the ‘unreasonably dangerous’ issue.” Id. 

Green Plains insists that the RTO’s design was defective and unreasonably

dangerous, emphasizing that the dampers use hydraulic pressure for movement, while

other potential designs, like compressed air or weighted dampers, could move the

dampers without a precharged accumulator. Green Plainsintroduced evidence of the

existence of alternative designs that are safer. 

Green Plains points to deposition testimony of the owner of a company that

designs ethanol production plants, where dampers move by compressed air, not

hydraulics. According to him, in a compressed-air system, dampers have an

automatic fail position and can fail “open” with a loss of pressure. Green Plains also

points to the testimony of its chief boiler engineer that after the explosion, Green

Plains added weights to the dampers so that if the hydraulics failed, employees could

manually open the dampers.

PEI counters that the RTO design was consistent with industry standards, and

that Green Plains’s expert never tested the alternative designs. The district court

ruled, “PEI’s design struck an acceptable balance among competing factors and was

not unreasonably dangerous.” Green Plains, 349 F. Supp. 3d at 775-76. 

While a manufacturer’s compliance with industry standards can be evidence

of a reasonable design, it “is not conclusive proof on the question of whether a

manufacturer exercised reasonable care.” Zimprich v. Stratford Homes, Inc., 453

N.W.2d 557, 560 (Minn. App. 1990), citing Schmidt v. Beninga, 173 N.W.2d 401,

408 (Minn. 1970). Here, Green Plains’s experts did not need to test the alternatives

to prove their feasibility, because they were successfully in use. See Young, 428 F.3d

at 790. “Credibility determinations, the weighing of the evidence, and the drawing

of legitimate inferences from the facts are jury functions, not those of a judge.” 

-5-
Torgerson, 643 F.3d at 1042, citingReeves v. Sanderson Plumbing Prods., Inc., 530

U.S. 133, 150 (2000). In Minnesota, “the jury ultimately decides whether the

[product is] unreasonably dangerous.” Young, 428 F.3d at 791. 

Because reasonable minds could differ about whether the RTO was defective,

Green Plains submitted sufficient evidence of a defective design to survive summary

judgment. 

III.

It is undisputed that if the accumulator had been recharged, the explosion

would not have happened. PEI argues that the lack of recharging is a superseding

cause that cuts off liability for any alleged defect. The district court was

“unconvinced that any alleged defect was the proximate cause of the fire and

explosion.” Green Plains, 349 F. Supp. 3d at 776. It ruled that “Green Plains’ own

lack of maintenance was a superseding cause that broke any causal connection

between an alleged design defect and the fire and explosion.” Id.

Proximate cause is generally a question of fact for the jury. Lubbers v.

Anderson, 539 N.W.2d 398, 402 (Minn. 1995). However, “where reasonable minds

can arrive at only one conclusion, proximate cause is a question of law.” Id. In a

proximate-cause analysis, Minnesota courts look to whether an injury “follows in an

unbroken sequence, without an intervening efficient cause, from the original

negligent act.” DeLuna v. Mower Cty., 936 F.3d 711, 717 (8th Cir. 2019), citing

Dellwo v. Pearson, 107 N.W.2d 859, 861 (Minn. 1961). A superseding event breaks

the chain of causation and “prevents the original negligent actor frombeing liable for

the final injury.” Wartnick v. Moss & Barnett, 490 N.W.2d 108, 113 (Minn. 1992).

-6-
An intervening act is a superseding cause if four elements are met:

(1) its harmful effects must have occurred after the original

negligence; (2) it must not have been brought about by the

original negligence; (3) it must have actively worked to

bring about a result which would not otherwise have

followed from the original negligence; and (4) it must not

have been reasonably foreseeable by the original

wrongdoer. 

Canada ex rel. Landy v. McCarthy, 567 N.W.2d 496, 507 (Minn. 1997). “A

defendant isliable, despite an intervening cause, if the cause is foreseeable.” Bilotta,

346 N.W.2d at 625. An injury is not reasonably foreseeable as a matter of law when

the undisputed facts, considered together, establish that the connection between

defendant’s conduct and the plaintiff’s injury was too attenuated. Montemayor v.

Sebright Prods., Inc., 898 N.W.2d 623, 629 (Minn. 2017). “[C]omparative

negligence does not automatically foreclose [the manufacturer’s] potential liability

for defective design and warnings. Rather, if reasonable minds could disagree as to

whether [the purchaser’s] negligence was reasonably foreseeable to [the

manufacturer], summary judgment must be denied.” Id. at 632.

The Supreme Court of Minnesota approvessubmitting to the jury a wide range

of superseding causes, including removing a detachable safety device, not heeding

the manufacturer’s warnings against unclogging a machine with the power connected,

and violating occupational safety regulations. Id. at 630-31, citing Germann v. F.L.

Smithe Mach. Co., 395 N.W.2d 922, 925 (Minn. 1986); Bilotta, 346 N.W.2d at 625;

Parks v. Allis-Chalmers Corp., 289 N.W.2d 456, 458-59 (Minn. 1979). This court,

applying Minnesota law, upheld a jury verdict because the manufacturer could

reasonably foresee the failure to pass along a machine’s operating manual, and the 

unfamiliarity of a trainer with the machine’s operating manual. See Bursch v.

Beardsley & Piper, 971 F.2d 108, 112 (8th Cir. 1992). This court held: “As to

machine maintenance, [the manufacturer]reasonably could have foreseen that[users]

-7-
would not maintain the machine in the strict manner recommended in the operating

manual.” Id.

PEI argues, as the district court ruled, that never recharging the accumulator

was a superseding cause because “it is unforeseeable that Green Plains would fail to

maintain its equipment.” Green Plains, 349 F. Supp. 3d at 776. True, Green Plains

did no maintenance on the accumulator despite the manual’s suggestion to check the

accumulator a week after installation and thereafter once a month. But, in order to

check the level of precharge in the accumulator, the machine had to be powered off,

fluid drained, and a charging and gauging assembly attached. Reasonable minds

could disagree whether PEI could foresee that a companywould view the “suggested”

maintenance as mandatory, or would ignore it due to the effort required. See Parks,

289 N.W.2d at 459 (“The jury could find that defendant knew, or in the exercise of

reasonable care should have known, that some users would leave the power

connected while unclogging because that would furnishmechanical assistance,saving

time and effort.”), approved in Montemayor, 898 N.W.2d at 630.

Under Minnesota law, PEI was not entitled to summary judgment on proximate

causation. 

IV.

Green Plains arguesthat PEI did not adequately warn that a failure to recharge

could cause an explosion. A failure-to-warn claim requires that: (1) PEI had a duty

to warn; (2) PEI breached that duty by providing an inadequate warning; and (3)

PEI’s inadequate warning caused Green Plains’s damages. See Kapps v. Biosense

Webster, Inc., 813 F. Supp. 2d 1128, 1155 (D. Minn. 2011), citing Balder v. Haley,

399 N.W.2d 77, 81 (Minn. 1987). “[A] supplier has a duty to warn end users of a

dangerous product if it isreasonably foreseeable that an injury could occur in its use.”

Gray v. Badger Mining Corp., 676 N.W.2d 268, 274 (Minn. 2004). This duty

-8-
extends to “all reasonably foreseeable users.” Hauenstein v. Loctite Corp., 347

N.W.2d 272, 275 (Minn. 1984). Whether a duty exists “is a legal issue for court

resolution.” Germann, 395 N.W.2d at 924. 

Here, PEI had a duty to warn Green Plains, a foreseeable user, of the dangers

of the RTO failing and exploding. The issues are whether the warnings were

adequate, and if inadequate, whether they caused the explosion. 

“To be legally adequate, a warning should (1) attract the attention of those that

the product could harm; (2) explain the mechanism and mode of injury; and (3)

provide instructions on ways to safely use the product to avoid injury.” Glorvigen

v. Cirrus Design Corp., 816 N.W.2d 572, 582 (Minn. 2012). “In any theory of

productsliability, the plaintiff mustshow a causal link between the alleged defect and

the injury.” Rients v. Int’l Harvester Co., 346 N.W.2d 359, 362 (Minn. App. 1984). 

Here, PEI gave Green Plains an RTO manual. It specifically warns, “Periodic

cleaning and maintenance of equipment is required. Failure to do so may cause the

equipment to malfunction with the potential for fire and explosion hazards.” The

“Maintenance” section of the manual also warns, with a cartoon “bomb” icon:

PERIODIC CLEANING AND MAINTENANCE OF

EQUIPMENT IS REQUIRED. FAILURE TO

UNDERTAKE SUCH ACTION MAY CAUSE

EQUIPMENT DAMAGE, IMPROPER FUNCTION, OR

THE CREATION OF AN EXPLOSIVE HAZARD.

PEI also gave Green Plains an HPU manual. It has instructions on the

maintenance of the accumulator, including how to check the precharge. This manual

warns:

It is imperative that personnel involved in the installation,

service, and operation of the power unit be familiar with

-9-
how the equipment is to be used. They should be aware of

the limitations of the system and its component parts; and

have knowledge of good hydraulic practices in terms of

safety, installation, and maintenance.

Green Plains argues that these warnings are inadequate because they do not

give adequate instruction for safe use, explain the injury from a failure to maintain

equipment, or provide instructions how to safely use the accumulator. Green Plains

asserts it did not know the importance of recharging the accumulator and that the

consequences were not sufficiently apparent. 

To the contrary, a warning label on the accumulator, under an all capital letters

“WARNING!”, says: “Failure to read and follow these directions can cause rapidly

discharging gas and/or hydraulic fluid which can result in death, personal injury and

property damage.” The label directs the reader to instructions in the product catalog

or on a website. The website, with detailed instructions, instructsreadersto check the

accumulator once per month. Also on the label is an instruction to “follow the above

mentioned bulletin for all servicing, including precharging and maintenance.” 

There must be a causal relationship between the failure to warn and the injury. 

Balder, 399 N.W.2d at 81-82 (finding no causation as a matter of law when a mother

and son disregarded verbal warnings and “[t]here is no reason to believe that a

warning label would have done anything more to impress [him] or his mother”). See

also Hauenstein, 347 N.W.2d at 276 (if the injured plaintiff would not have acted any

differently had there been warning, manufacturer’s failure to warn is not cause of

injury). 

“Absent a reading of the warning, there is no causal link between the alleged

defect and the injury.” J&W Enters., Inc. v. Econ. Sales, Inc., 486 N.W.2d 179, 181

(Minn. App. 1992). “[A]n issue as to the adequacy of a warning necessarily

-10-
presupposes that the operator has read the warning.” Johnson v. Niagara Mach. &

Tool Works, 666 F.2d 1223, 1225 (8th Cir. 1981) (applying Minnesota law).

The Chief Boiler Engineer at Green Plains testified he glanced through the

manuals, but did not read them cover to cover. He testified he understood the role of

the accumulator and knew that the accumulator’s precharge needed to be checked. 

He also acknowledged he was not aware that the HPU manual discusses checking the

accumulator precharge. The warning label on the accumulator specifically says to

followinstructionsfor precharging andmaintenance. Additional warnings would not

have changed the behavior of Green Plains. 

The district court properly granted summary judgment on the failure-to-warn

claim.

* * * * * * *

The judgment as to failure-to-warn is affirmed. The judgment as to defectivedesign isreversed, and the case remanded for further proceedings consistent with this

opinion. 

______________________________

-11-