The Westwego City Council is expected to approve changes Monday night to city ordinances that govern hazardous materials stored at industrial facilities.

The changes won’t have any practical effect on materials at existing facilities but instead stem from the realization that Westwego’s regulations weren’t as comprehensive as they should be, officials said.

Mayor John Shaddinger said adopting the same definition of hazardous materials that Jefferson Parish uses is good policy that will keep residents safe.

The changes have been in the works for a couple of months, but the council had to hold off on acting at its June meeting because of a timing issue: One of the three alterations was only up for introduction, not adoption, and representatives from companies with plants in the city, along with several council members, said that only partially rewriting the laws — even for just 30 days — could create liability issues.

The first of the three changes inserts the parish’s definition of hazardous materials — including oils, pesticides, asbestos, radioactive waste and other materials — into the city’s fire protection ordinance.

The second puts the term “hazardous materials” into the city’s planning and zoning ordinance in place of what are now defined only as “petroleum products.”

The third change — the one that caused the delay last month — involves tweaking the section of the planning and zoning rules on facilities with nonconforming uses.

The changes have their roots in the city’s discovery last year that Blackwater Midstream LLC had been storing 20 products at its 26-acre terminal on River Road that were not allowed under the city’s laws.

Blackwater said it was following state Department of Transportation and Development guidelines, which don’t consider the materials to be combustible, but the city was using National Fire Protection Association guidelines, which do.

The city ended up giving Blackwater an exemption for materials that were already there, provided it moved them farther away from homes and put in a new fire-suppression system, which is underway.

It was during this process that the city decided to take a look at all its ordinances relating to hazardous materials and bring them in line with the parish’s.

The discussions between Blackwater officials and council members have been contentious at times, but the city and the company are in agreement about the changes expected to be made Monday at 6 p.m. at City Hall on Avenue A.

Follow Chad Calder on Twitter, @Chad_Calder.