Environmental officials have cleared Croda Inc.'s ethylene oxide unit at Atlas Point on the Delaware River to reopen, just in time for the first anniversary of the Nov. 25, 2018, toxic gas leak that shut Delaware Memorial Bridge traffic between New Jersey to Delaware and snarled homebound Thanksgiving travelers on I-95 and other roads for seven hours.

“We have given Croda the go-ahead to start up,” said Joanna Wilson, a spokesperson for the Delaware Department of Natural Resources and Environmental Control. “Croda is looking to begin the process of getting back online this week, but they have indicated it will take a while before the plant is fully operational.”

The unit can produce two tons of the useful, volatile, carcinogenic hydrocarbon per hour. The U.K.-based Croda built the plant at its 82-year-old Atlas Point complex in 2017-18. Its contractors hired hundreds of construction workers to install technology previously used at plants in India and China.

Firefighters sprayed 700,000 gallons of water to dispel 2.3 tons of leaked ethylene oxide plus byproduct 1,4 dioxane; the Delaware River and Bay Authority closed the bridge as a precaution while emergency crews tested for exposure.

The week after the accident, Croda blamed the shutdown on a failed gasket installed by contractors during construction, and began replacing other gaskets to guard against more leaks. The company and local fire officials originally said no one was hurt in the accident, later acknowledging that five workers sought medical observation. The federal Occupational Safety and Health Administration and state agencies imposed more than $500,000 in fines and penalties on Croda for operating the plant without proper inspection, failure to train workers adequately, and other failures leading up to the leak.

The reopening was approved last week, according to a statement by Shawn M. Garvin, the Delaware Department of Natural Resources and Environmental Control secretary. The department said Croda had taken all steps demanded by the state: an internal investigation report, plus analyses of leak hazards, fire systems, training in fire management, plant operation and emergency response, pipe connections between Croda and local fire departments, and a safety review.

Croda also added automated valves to isolate and purge toxic chemicals; 26 new ethylene oxide gas detectors; and eight more closed-circuit TV cameras, and “upgraded its vapor suppression capabilities.” State and county emergency officials also prevailed on the company to add emergency sirens to supplement automated phone notices and other emergency warnings, by Jan. 31. DNREC and other state and local agencies met with neighbors in December and August to review Croda’s steps.

Croda built the facility at its plant as a new source of ethylene oxide after a fire shut Croda’s former supplier at Sunoco’s Marcus Hook works and forced Croda to ship the volatile chemical by rail from Texas, with higher costs and contamination risk. The new facility makes ethylene oxide from ethanol -- the common hydrocarbon that makes people drunk and is safer to ship.

The plant, which employs 250, has remained open during repairs and testing, with raw materials again shipped from the Houston area. Ethylene oxide and other chemicals are used to make surfactants -- emulsifying (mixing) agents that help keep oil and water together, and are used in products from face cream and toothpaste to paints, antifreezes and detergents, as well as in the processed foods, gas-and-oil, and other basic industries.

Though it was initially controversial -- New Castle County officials had preferred a new port development for that location, which has been overtaken by suburban development since the twin bridges connecting Delaware to the New Jersey Turnpike opened in the 1940s -- Croda’s investment was touted by state officials as a sign of renewal for the aging chemical industry along the Delaware River, where outdated oil, steel, chemical, and rail-equipment plants have closed in the last few decades as U.S. companies preferred to invest in lower-cost areas.

Croda originally said it would spend $170 million on the new plant, including $2.9 million in state aid. But plans for some of the structures on site were reduced in scale, according to state records, and Croda has not confirmed what it actually spent.