Toxic Gas Brings Call for Subway Work Delay : Transportation: Official urges further study of hydrogen sulfide along route to Mid-City area. MTA board is expected to consider recommendation Jan. 26.

Concerns about concentrations of toxic, highly corrosive hydrogen sulfide gas in the path of the Metro Rail subway’s planned extension into the Mid-City area have prompted transportation officials to recommend putting all work on hold, pending further study.

The recommendation, if approved, will delay construction of the 2.3-mile southern extension of the Red Line by at least nine months, officials acknowledged Wednesday.

Construction was scheduled to begin in September, with the opening of the segment planned for sometime in 2000.

“The problems we have encountered obviously are serious and demand careful study by the best experts available,” Edward McSpedon, president of the Metropolitan Transportation Authority’s Rail Construction Corp., said in a strongly worded statement urging approval of the study. “As much as we may want to begin construction of a Mid-City segment, there are times when it is more important to do it right than to do it quickly.”

McSpedon emphasized that “our first concern is for the safety of the public and of the men and women who will build and operate the subway.” He said that the reassessment would include a look at various construction and technological methods for safely tunneling in the area, and possibly changing the route.

The MTA board is expected to act on the recommendation for a nine-month study at its next meeting, Jan. 26.

MTA spokesman Bill Heard said the presence of hydrogen sulfide became known to rail officials in August, 1992. But engineers at the time believed they could use several treatment technologies to remove or neutralize the gas.

However, further probes of the site in August, 1993, led officials to conclude that the concentrations were heavy enough to warrant reconsideration of the construction plans, Heard said.

Approved in September, 1992, the $490-million Mid-City extension route is to begin at Wilshire Boulevard and Western Avenue, continuing southwest to Olympic and Crenshaw boulevards and then to Pico and San Vicente boulevards. Preliminary design of the stations and tunnels began in March and a grant for full funding by the Federal Transit Administration was received in May.