CORNERSTONE CHEMICAL COMPANY, Westwego, LA: NPDES LA0004367 discharge permit, effluent exceedances, inspections, penalties

CORNERSTONE CHEMICAL COMPANY, Westwego, Louisiana: Individual permit LA0004367; Administratively continued; issued June 19, 2015, term to July 31, 2020; discharges to LAKE CATAOUATCHE; Plastics, Foil, and Coated Paper Bag Manufacturing [2007].

44 of the 60 pollutants listed for NPDES LA0004367 have no violation or effluent exceedance.

• Coliform, fecal general: 2 limits, 8 violations of any kind, 8 effluent exceedances, latest July 31, 2025, largest 99,999% over the limit.
• pH: 4 limits, 8 violations of any kind, 4 effluent exceedances, latest June 30, 2025.
• Oil and grease: 3 limits, 5 violations of any kind, 4 effluent exceedances, latest July 31, 2018, largest 57% over the limit.
• BOD, 5-day, 20 deg. C: 2 limits, 3 violations of any kind, 3 effluent exceedances, latest August 31, 2023, largest 23% over the limit.
• Nitrogen, organic total [as N]: 2 limits, 3 violations of any kind, 3 effluent exceedances, latest June 30, 2020, largest 89% over the limit.
• Nitrogen, ammonia total [as N]: 3 limits, 4 violations of any kind, 2 effluent exceedances, latest October 31, 2023, largest 22% over the limit.
• Oxygen demand, chem. [high level] [COD]: 1 limit, 4 violations of any kind, 2 effluent exceedances, latest June 30, 2025, largest 77% over the limit.
• Acrylonitrile: 4 limits, 1 violation of any kind, 1 effluent exceedance, latest December 31, 2015, largest 27% over the limit.
• Solids, total suspended: 2 limits, 1 violation of any kind, 1 effluent exceedance, latest March 31, 2020, largest 111% over the limit.
• Cyanide, total [as CN]: 2 limits, 1 violation of any kind, 1 effluent exceedance, latest May 31, 2017, largest 411% over the limit.
• Copper, total [as Cu]: 2 limits, 1 violation of any kind, 1 effluent exceedance, latest March 31, 2026, largest 113% over the limit.
• pH range excursions, > 60 minutes: 1 limit, 1 violation of any kind, 1 effluent exceedance, latest February 29, 2024, largest 2,147,483,650% over the limit.
• Zinc, total [as Zn]: 2 limits, 38 violations of any kind.
• Flow, in conduit or thru treatment plant: 6 limits, 6 violations of any kind.
• Phosphorus, total [as P]: 1 limit, 2 violations of any kind.
• Oil & Grease: 0 limits, 1 violation of any kind.
• Whole effluent toxicity - retest #1: 8 limits.
• Whole effluent toxicity - retest #2: 8 limits.
• Whole Effluent Toxicity - Retest #3: 8 limits.
• Carbon tetrachloride: 4 limits.
• 1,2-Dichloroethane: 4 limits.
• Chloroform: 4 limits.
• Toluene: 4 limits.
• Benzene: 4 limits.
• Acenaphthylene: 4 limits.
• Acenaphthene: 4 limits.
• Anthracene: 4 limits.
• Benzo[b]fluoranthene: 4 limits.
• Benzo[k]fluoranthene: 4 limits.
• Benzo[a]pyrene: 4 limits.
• Chlorobenzene: 4 limits.
• Chrysene: 4 limits.
• Diethyl phthalate: 4 limits.
• Dimethyl phthalate: 4 limits.
• Ethylbenzene: 4 limits.
• Fluoranthene: 4 limits.
• Fluorene: 4 limits.
• Hexachlorobutadiene: 4 limits.
• Hexachloroethane: 4 limits.
• Methyl chloride [Chloromethane]: 4 limits.
• Methylene chloride: 4 limits.
• Nitrobenzene: 4 limits.
• Phenanthrene: 4 limits.
• Pyrene: 4 limits.
• Tetrachloroethylene: 4 limits.
• 1,1-Dichloroethane: 4 limits.
• 1,1-Dichloroethylene: 4 limits.
• 1,1,1-Trichloroethane: 4 limits.
• 1,1,2-Trichloroethane: 4 limits.
• Benzo[a]anthracene: 4 limits.
• 1,2-Dichlorobenzene: 4 limits.
• 1,2-Dichloropropane: 4 limits.
• trans-1,2-Dichloroethylene: 4 limits.
• 1,2,4-Trichlorobenzene: 4 limits.
• 1,3-Dichlorobenzene: 4 limits.
• 1,4-Dichlorobenzene: 4 limits.
• 2-Nitrophenol: 4 limits.
• 2,4-Dimethylphenol: 4 limits.
• 2,4-Dinitrophenol: 4 limits.
• 4-Nitrophenol: 4 limits.

• March 25, 2026: Letter of Violation/ Warning Letter (State).

CORNERSTONE CHEMICAL COMPANY among its neighbors

1 discharge permits are in the Old River-Intracoastal Waterway subwatershed (HUC 080801010305); LA0004367 is one. Its county: 143, 19 major; LA0004367 is major permit.