## Facts

- A bridge project in Philadelphia used a contracting chain in which Groves served as the concrete placement subcontractor and Warner supplied ready-mixed concrete under a supply contract.
- Warner agreed to supply roughly 35,000 cubic yards of concrete at an estimated delivery rate of 40 cubic yards per hour at times specified by Groves.
- The project suffered delays from several strikes, and Groves also complained that Warner frequently made nonconforming or late deliveries that forced schedule adjustments and increased labor costs, including overtime.
- On July 9, 1970, the first concrete deck pour produced a defective panel. The trial court found the defect resulted from both Warner’s defective concrete and Groves’ inadequate workmanship, and it awarded Groves only a portion of the removal-and-replacement costs.
- In 1972, Groves investigated using Trap Rock as an alternative supplier. Initially Trap Rock was not certified for state work and would have charged more.
- On June 21, 1972, the state halted construction because of concerns about Warner’s performance; work resumed June 26 after a conference and Warner’s assurances, but performance remained erratic.
- On July 11, 1972, Trap Rock became certified and agreed to match Warner’s price. Groves nonetheless continued using Warner exclusively through completion in October 1972.
- After a bench trial, the district court entered judgment for Groves for $35,401.28 but limited “delay damages,” reasoning Groves had a duty to mitigate by using Trap Rock as a supplemental supplier once it became available.

## Issues

1. Whether the district court clearly erred in allocating only part of the July 9, 1970 defective-pour costs to Warner where multiple causes contributed to the loss.
2. Whether the district court applied an overly rigid mitigation rule by cutting off delay damages after July 11–12, 1972 based on a supposed obligation to add Trap Rock as a supplemental supplier.

## Decision

- The Third Circuit affirmed the judgment in most respects but reversed in part and remanded because the district court construed mitigation too narrowly.
- The court affirmed the district court’s allocation of damages for the July 9, 1970 defective panel, emphasizing the plaintiff’s burden to prove what portion of loss was proximately caused by the supplier’s breach rather than other factors.
- On mitigation, the court agreed that an injured party must take reasonable steps to reduce loss, but held that continued reliance on an unsatisfactory performer can be reasonable where switching or splitting performance may create additional risks and costs.
- The court remanded for recalculation of delay damages under a reasonableness-based mitigation analysis rather than a fixed cut-off date tied solely to the availability of an alternative supplier.

## Legal Principles

- A plaintiff seeking contract damages must prove proximate causation and quantify loss attributable to the breach; when loss cannot be separated from other causes, recovery may be denied for the inseparable portion.
- When both parties’ conduct contributes to a construction defect, a factfinder may allocate responsibility, and appellate review is deferential to supported factual findings.
- The duty to mitigate requires reasonable care, not measures that are speculative, unusually burdensome, or likely to increase total loss.
- The existence of an alternative supplier does not automatically require substitution or supplementation; mitigation must be assessed in context, including operational disruption, timing, and foreseeable risks.
- In some construction settings, continuing with an unsatisfactory contractor or supplier may be a reasonable mitigation choice if changing performers would likely create additional losses.

## Conclusion

The Third Circuit largely upheld the trial court’s fact-bound damage determinations, including shared-causation allocation for the defective first pour, but held that mitigation cannot be applied mechanically; it remanded for reconsideration of post–July 1972 delay damages under a context-specific reasonableness standard.


S.J. Groves & Sons Co. v. Warner Co., 576 F.2d 524 (3d Cir. 1978)