The city of Los Angeles soon will start a major sewer infrastructure improvement program after El Nino flooding forced the hand of the regional water quality control board.
A cease and desist order from the board will cause the city to spend almost $378 million over the next five years, almost half of the $767.4 million total amount the city expects to spend on wastewater capital improvement projects during the period.
Torrential rain caused by El Nino weather patterns led to several wet weather spills in the sewer system that runs through the city. The pipes, many more than 70 years old, were very corroded and had structurally deteriorated. As a consequence of the overflows, the board mandated a special repair program.
"It is very similar to a regular contract, but this is a mandated sentence, sort of. If we dont get it done within the time allotment, the city gets assessed liquidated damages. Its a very expensive proposition if we fail to meet the timeline," said Wayne Savaria, Division Engineer for the Collection Systems Engineering Division.
The Cease & Desist Order Program will take at least five years. Most of the money from the wastewater treatment plant program, formerly the lions share of the budgeting, is being diverted now to the collection systems side.
Large projects planned in Los Angeles include the East Central Interceptor Sewer (ECIS), which will cost approximately $215 million and take about three years. The tunnel sewer will be 8 to 12 feet in diameter and 11 miles long. It will be a major backbone - a collection point for many sewers in the area. This project is in the final design phase and hopefully will be started in January 2001, according to Baron Miya, Assistant Division Engineer.
"Our major consideration with building a project like this is not so much the design - the design is fairly simple. Its the acquisition of right of ways and properties and dealing with the communities. Thats where a lot of the time is spent on a project of this scope," Savaria said.
Many of the citys sewers are 70 years old and made of rows of bricks arranged in a semicircle over a flat bottom of reinforced cast-in-place concrete. The cavity around the tunnel was filled with wood lagging, and it is falling apart. This is causing collapses.
The North Outfall Sewer (NOS), which goes all the way through the city, is about 35 miles long. The 60 to 70-year-old sewer will benefit from many of the projects included in the Cease & Desist Order Program, since they can take on some of the volume carried by the old line. The NOS line will be rehabbed starting in fiscal year 2003/2004.
The NorthEast Interceptor Sewer, to be replaced starting in late 2001, is expected to cost the city $150 million. This 6-8 ft. diameter sewer is about 9 miles long and runs parallel to the NOS sewer. When it is completed, it will create relief for the NOS sewer. Four other sewer rehab projects combined will cost approximately $117,426,000.
Over the next five years, L.A. also plans to spend $256,966,000 on collection system sewer repair, $179.2 million on pumping plants, $72,173,000 on a cement sewer replacement program, $7.5 million on emergency sewer repairs, and $35 million on an accelerated sewer repair program.
The schedule will be very compressed because of the mandatory nature of the projects. ECIS will start first, but the projects will be overlapping for the next five years.
Bids are currently being accepted on two smaller projects, Eastern Relief Sewer and North Hollywood Relief Sewer Unit 1. Specifications include the option of microtunnelling vs. open trenching, Miya said.
