Los Angeles Reaches 1 Million Ft of Sewer Using Trenchless Methods
June 29, 2011The City of Los Angeles recently completed 1 million ft of sewer that has been constructed or rehabilitated using trenchless technologies.
The City has an aggressive sewer rehabilitation program to manage effectively and renew its 6,700-mile wastewater sewer system. Always pursuing new, better technologies to protect the City’s aging infrastructure as a valuable resource, the City has embraced trenchless sewer construction methods. These trenchless techniques are easier on the community while also minimizing costs and environmental impacts.
“Angelenos spend a lot of time driving, and traffic in this City is legendary. Our engineers recognized this challenge and found a way to keep people moving while also accomplishing the important work of renewing the sewer system. I applaud staff for this innovative thinking and am excited that Los Angeles is first in reaching this 1 million-ft milestone,” said city engineer Gary Lee Moore.
“Renewing our world-class wastewater system is essential to the Bureau of Sanitaton’s mission of protecting public health and the environment,” said Bureau of Sanitation Director Enrique C. Zaldivar. “Trenchless construction methods offer a win-win because we are able to get the work done with fewer impacts to our partners in the community.”
The City has carried out its mandate to protect the health and safety of its residents while also avoiding more than a million feet of trench, thereby reducing traffic impacts and inconvenience to adjacent homes and businesses. Also, trenchless methods of sewer repair are often less expensive than traditional sewer replacement. Since the launch of trenchless methods more than 15 years ago, the City has saved more than $80 million in construction costs. Traditional open-cut sewer rehabilitation costs approximately $125 per lf and trenchless methods average about $30 per lf.
Especially in these difficult budget times, that savings is vital to the program’s success. Various trenchless methods have been used to install new sewers, including tunneling, microtunneling and horizontal directional drilling. Trenchless methods also have been used to rehabilitate existing sewers, including sliplining with circular pipe segments, non-circular pipe segments, and high density polyethylene pipe; lining pipes with cured in place liners, fold and form liners; and casting concrete-supported PVC corrosion resistant liners in place.
Because the City is at the forefront of this trenchless trend, other agencies nationwide and abroad have sought information about the results Los Angeles is seeing. The City has implemented leading edge methods and has worked with manufacturers to develop techniques to rehabilitate large, non-circular sewers, live and in place.
Trenchless methods have been used to rehabilitate existing sewers from 6 to 120 in. in size, and to install new sewers up to 150 in. in diameter. Materials that have been used in either new construction or rehabilitation include vinylester resin cured-in-place pipe, HDPE slipliner, fold-and-form, PVC cast in place liner and fiberglass reinforced pipe.
In order to produce the plans needed to carry out this work, the City has been creative in developing and copyrighting a proprietary software package, SMARTS (Sewer Management Automated Repair Tracking System) program. SMARTS is used to prepare plans for the Secondary Sewer Renewal Program that rehabilitates an average of 60 miles of 8- and 16-in. pipe each year. This program produces a reduced format design and bidding package, usually with no drawings, that significantly reduces the cost and time of preparing plans and specifications. This program employs state-of-the-art GIS technology, electronic vault plan retrieval, and sewer video to bring all of the necessary information for the design of sewer rehabilitation projects to the engineer’s desktop.
The City of Los Angeles will continue to explore more efficient techniques of managing its wastewater system, and trenchless methods certainly will continue to be an effective means of achieving that end. Stakeholders can make or break any construction project, so trenchless technologies go a long way in securing public support by limiting project duration, traffic impacts and other community disruptions. It only helps that these methods also offer budget savings and environmental benefits as well.
The Department of Public Works is the second largest municipal agency in the City, focused on essential needs for a better quality of life and environmental protection. The department is responsible for construction, renovation and operation of public facilities and infrastructure including: municipal buildings and treatment facilities; streets, street lights, and the urban forest; bridges and sidewalks; sewers, catch basins and storm drains; recycling and integrated solid waste management.