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| The Sewerage System Upgrades |
| Upgrade Overview |
The Sewerage and Water Board (S&WB) of New Orleans began a major
rehabilitation and capacity upgrade of its aging sewage collection system in
1996, following a public hearing to obtain citizen input on the plan.
Like
most of the nation's major metropolitan areas, New Orleans' underground water
and sewer systems are at least 40 years old and, in many cases, up to 100 years
old. Factors common to this area, such as unstable soil conditions and large
numbers of tree roots, contribute to a higher-than-normal number of breaks and
deterioration of the sewer pipes.
At the public meeting, the S&WB's
staff and consultants provided details of the now $600 million multi-year
program to the public, environmental, preservation and neighborhood groups,
elected officials and the news media.
The SSERP, or the Sewer System
Evaluation and Rehabilitation Program, was eventually incorporated into the
consent decree the S&WB signed with the EPA in 1998. At that time,
timetables and deadlines were established for the work in each district.
The
S&WB selected Montgomery Watson Harza (MWH), a global leader in large
capital program management, to serve as SSERP program manager. MWH's program
management experience includes planning and management of design and
construction of extensive sewer rehabilitation-related projects in Houston,
Baton Rouge, Miami and San Francisco.
In addition, the S&WB sought out
EPA Federal grants to support the program totaling approximately $100 million
over 10 years. The $100 million has been authorized by Congress. To date the
Sewerage and Water Board has received $38.8 million in Federal Funds.
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| Rebuilding New Orleans' Underground |
Currently, the sewage collection system services an area of approximately 86 square miles
and a population of approximately 497,000. It consists of over 1,600 miles of
gravity collection and trunk sewers ranging in size from 8 inches to 84 inches
in diameter and over 100 miles of force mains ranging in size from 6 inches to
72 inches in diameter. There are 83 pump stations which help convey wastewater
to the City's two wastewater treatment plants, one on the East Bank and one on
the West Bank (Algiers) of the Mississippi River with a combined capacity of 132
million gallons per day (mgd).
The SSERP program will rehabilitate this
wastewater system using state-of-the-art trenchless and traditional methods. The
trenchless methods allow for rehabilitation of buried pipe and manholes without
the need for excavation and the disturbance to residents that it causes.
The
project is divided into ten districts. Each year, one of these districts will
undergo a system evaluation survey that will result in an estimated $12 to $47
million in sewer structural rehabilitation needs. This comprehensive study
includes smoke and dyed water testing, flow and rainfall monitoring, manhole
inspections and surveys, and closed circuit televising (CCTV) of approximately
35 percent of the system. Sonar technology is also employed to determine the
condition of sewer lines that cannot be de-watered.
In fact, SSERP engineers
developed a computerized decision model to automatically determine a
cost-effective rehabilitation method from encoded CCTV data. Engineers record
detail sewer data for each study area -- such as location, size and current
conditions -- using a closed-circuit television recording device. That data is
electronically transferred to the computer decision model, where algorithms
determine efficient repair methods based on existing conditions and the
S&WB's rehabilitation strategy. This process has helped reduce design time
and costs so more dollars can be utilized for rehabilitation measures.
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| Early Efforts Completed On-time and Within
Budget |
So far, sewer evaluation surveys have been completed in the
Lakeview and Gentilly districts located adjacent to Lake Pontchartrain, Uptown,
Lower Ninth Ward, Carrollton, and in the Central Business District, Warehouse
District and French Quarter (CBD/WD/FQ) areas. Survey efforts in the New Orleans
East district were initiated in early 2003.
The Lakeview area district sewer
structural rehabilitation was completed at the end of 2001. These efforts
included manhole rehabilitation, gravity sewer pipe lining, excavated point
repairs and replacement, resulting in the rehabilitation of some 2,000 manholes
and over 163,000 feet of sewer line.
Marcia St. Martin, interim executive
director of the Sewerage & Water Board, explained: "We've learned a lot
during the rehabilitation of this first district. Our contractors and suppliers
need to offer speed and versatility to support this massive job in the
turnaround that we need to support the stringent EPA guidelines."
In addition
to the Lakeview area, construction activity in the Central Business
District/French Quarter district is well underway. Work in this area includes
cleaning and televising over 300,000 feet of sewer line, rehabilitating some 650
manholes and nearly 70,000 feet of sewer line.
Contractors are rehabilitating
aging sanitary sewer manholes through the addition of lightweight cementitious
lining, replacing frames and covers, installing flexible corbel seals, and
simply raising of covers to match adjacent ground levels. These adjustments are
very extensive due to New Orleans' dynamic soil conditions.
D&O
Contractors, Inc. of Kenner, Louisiana, was charged with rehabilitating nearly
1,200 of these manholes in the Lakeview area district, relying on lightweight
cementitious liner to complete the job. SSERP engineers selected cementitious
liners because the application and installation are effective, straightforward
and relatively quick. The rehabilitation effort for another 800 manholes in the
Lakeview district was completed by E.B. Feucht and Sons of Eunice,
Louisiana.
Prior to the installation, each manhole is cleaned with a minimum
3500 pounds per square inch (psi) hot water pressure wash and steam. Next, the
lining is applied through a spray process and troweled smooth. Then crews apply
a flexible urethane coating to seal the lining on the wall to the metal casting.
This seal allows expansion and contraction while remaining water tight within
the manhole wall structure, which is stationary and expands at a different rate
than the metal casting.
In terms of gravity sewer pipe rehabilitation, the
job is much larger.
Crews from Boh Brothers Construction Co., LLC, of New
Orleans, Insituform Technologies, Inc. of Hammond, Louisiana, and Fleming
Construction Company of Metairie, Louisiana, as of May 2003, have completed
cured-in-place manhole-to-manhole lining of over 200,000 lineal feet of existing
sanitary sewer (8-inch to 30-inch diameter) as part of the contracts awarded
through the SSERP program.
The SSERP projects began in May 1999 and,
according to contract guidelines, required the teams to meet interim milestones
during the project timeline. Failure to complete the designated rehabilitation
or reconstruction activities may have resulted in significant monetary
penalties. All contracts for sewer rehabilitation performed under the SSERP have
met all required milestones resulting in no penalties for non-compliance. The
majority of the effort is focused on trenchless pipeline reconstruction but also
includes excavated point repairs, the rehabilitation of service laterals, site
video work and the conventional excavated replacement.
Much of the
trenchless pipeline reconstruction will be accomplished using a polyester felt
liner impregnated with resin and inverted into the damaged pipe with water, then
cured in place with hot water to the shape of the host pipe. During the
installation process, the resin is forced into cracks, joints and other
irregularities of the host pipe to form a mechanical lock between the host pipe
and the liner that holds them firmly in place. After the new pipe has cured,
service lateral lines will be reopened with a remote-controlled robotic cutter.
Additional contracts for the rehabilitation of the remaining 40,000 lineal
feet of existing sewers to be rehabilitated in the Central Business District
will be completed by the end of 2005.
Sewer design and structural
rehabilitation activities in the Gentilly area began in July 2001. The
rehabilitation work in this area includes rehabilitating some 1,600 manholes and
163,000 feet of sewer line. The contracts are being performed by D&O
Contractors, Boh Brothers Construction, and Wallace C. Drennan of New Orleans,
Louisiana, and Roland Pugh Construction Birmingham, Alabama.
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| The Sewer Rehabilitation Future |
Surveys in the remaining districts will be conducted at a rate of one per
year, with the final survey scheduled for completion in 2006. In addition,
planning is ongoing for numerous capacity related projects, which will provide
for improved hydraulic capacity to pump stations and force mains. Actual
construction and remedial work in the nine districts on the East Bank must be
completed by 2010, according to consent decree requirements.
Thus far, the
Sewerage and Water Board and its contractors have met the tight consent decree
timeline for the initial phases of the project--most ahead of schedule. In
addition, the traffic delays along several major avenues were cut in half by the
use of trenchless technology.
At this time, discussions of future funding
options are underway by the S&WB, its financial advisors and bond counsel.
The future of SSERP, naturally, depends on the availability of funds to complete
the projects and complete them in accordance with EPA deadlines to avoid large
fines of up to $15,000 per day.
The S&WB has kept the public informed of
the SSERP projects through billing inserts, its website, news releases, media
briefings, public hearings and meetings, special neighborhood meetings and
participation in meetings scheduled by the Mayor or councilpersons.
Because
of the high visibility of smoke and dyed water testing and televising of the
sewer lines, the S&WB schedules special demonstrations of the tests prior to
work beginning. Invited to the demonstrations are area residents, neighborhood
and civic associations, environmental groups, elected officials and the
media.
To date, over $93 million has been expended for work identified under
the SSERP. In addition, the following inspection and rehabilitation efforts have
been completed so far:
* 5.1 million feet of sanitary sewer pipe have been
inspected;
* Over 291,000 feet of sewer pipe have been rehabilitated;
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Over 19,200 sewer manholes have been inspected; and
* Over 2,600 sewer
manholes have been rehabilitated. |
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