Residents along Saw Mill Creek in Allegheny County sued Keystone Plating LLC for private nuisance, negligence, and trespass. They allege that after a 2024 expansion, oily runoff and metallic odors appeared after storms, fish died in the creek, and outdoor use of their yards became unpleasant. Keystone operates under a state discharge permit and says its outfalls stayed within limits. The company blames a cracked municipal storm sewer and decades of upstream industrial contamination. Plaintiffs seek remediation costs, property-value loss, and injunctive relief.
Creek water sampling results
Plaintiff samples after three storms show elevated nickel and chromium downstream of Keystone outfall K-3. Keystone split samples from dry-weather days show concentrations below permit limits. Sampling timing is heavily disputed. Trial use: Supports contamination near Keystone outfall, but storm timing and split-sample differences leave source and representativeness disputed. Foundation: The sponsoring expert should explain qualifications, source data, method, assumptions, and whether the opinion reliably fits the disputed issue. Cross-examination focus: Sampling Reliability FRE 702.
State discharge permit and monitoring reports
Keystone monthly discharge monitoring reports show no permit exceedances in 2024. Plaintiffs argue the permit does not authorize nuisance and does not capture storm surges. Trial use: Shows regulatory compliance, while plaintiffs can argue permit compliance does not defeat nuisance or storm-event contamination claims. Foundation: A custodian, author, recipient, or investigator should authenticate when it was made, how it was preserved, and how it connects to the disputed event. Cross-examination focus: Legal Relevance Dispute.
Drone video after July storm
Drone footage taken by a resident shows cloudy water leaving the area of outfall K-3 into Saw Mill Creek. Keystone says the video cannot identify the source and was filmed after public storm drains overflowed. Trial use: Visualizes cloudy discharge after a storm, but source identification and storm-drain overflow give Keystone authentication and causation attacks. Foundation: A custodian, author, recipient, or investigator should authenticate when it was made, how it was preserved, and how it connects to the disputed event. Cross-examination focus: Authentication FRE 901; Foundation Issue.
Municipal storm sewer repair file
Borough records show a cracked storm sewer 400 yards upstream, repaired in September 2024. Keystone argues it carried road contaminants into the creek. Plaintiffs note sampling spikes are highest below Keystone, not above it. Trial use: Provides an alternative upstream contamination source, while downstream concentration patterns let plaintiffs contest that explanation. Foundation: A custodian, author, recipient, or investigator should authenticate when it was made, how it was preserved, and how it connects to the disputed event. Cross-examination focus: Causation Dispute.
Real estate appraisal report
Plaintiff appraiser estimates a 12% stigma reduction for creek-facing homes. Defense appraiser says market data show no statistically significant discount compared with similar nearby homes. Trial use: Measures alleged property stigma damages, but dueling market analyses make valuation and causation open to expert challenge. Foundation: The sponsoring expert should explain qualifications, source data, method, assumptions, and whether the opinion reliably fits the disputed issue. Cross-examination focus: Expert Methodology FRE 702.
Nora Feldman (homeowner plaintiff)
Lives 200 feet from Saw Mill Creek downstream of Keystone
After the plant expansion, the creek smelled metallic after storms and we saw dead fish twice. We stopped letting our kids play near the water. I reported the cloudy discharge because it came from the plant side.
Graham Pike (Keystone plant manager)
Operations manager responsible for permit compliance
Keystone monitors its discharge and stayed within permit limits. We invested in containment during the expansion. The creek has legacy contamination and the borough sewer was cracked upstream, which explains storm-related problems.
Dr. Priya Raman (environmental engineer)
Plaintiff expert in industrial hydrology and contaminant transport
The pattern of nickel and chromium spikes downstream of K-3 after storms is consistent with runoff from a metal finishing operation. Upstream samples and storm sewer records do not explain the magnitude of downstream increases.
Industrial Runoff Nuisance — Pittsburgh, PA
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