Multi-Million Dollar Sewer Rehab Program In New Orleans.
The ambitious rehabilitation program was developed after the federal government filed suit against the City of New Orleans, the Sewerage and Water Board of New Orleans (S&WB) and the State of Louisiana, alleging violations of the Clean Water Act. Ultimately, an agreement was reached with the Department of Justice and the Environmental Protection Agency (EPA) that allowed the Sewerage and Water Board (S&WB) of New Orleans to go forward with the EPA-approved SSERP to prevent discharges and overflows from the sewage system. The resulting consent decree for the City of New Orleans, mandated numerous changes, including:
* increased preventative maintenance of the sewage system;
* sealing or closing cross connections between sanitary sewerage and the drainage system; and,
* increasing training and public education.
To ensure that the city's most pressing problems were addressed first, the city's 86-mile service area was divided into 10 separate basins. The decree set subsequent due dates for completion of collection system evaluations and remedial measures in each respective basin. The order of basin studies and plans of remedial action is part of the criterion approved by the EPA as well, and establishes the sequence, consistent with the condition and needs of each basin. The order of priority is based on a worst case basis, except for the Lakeview and the Central Business District (CDB) basins, since studies were initiated by the S&WB prior to entering into the decree.
Funding for all SSERP projects will come from three sources: Federal funds, via an EPA grant of $100 million; S&WB matching funds of $81 million, and other S&WB funds of $19 million. The S&WB has a commitment from the U.S. Congress for $26.5 million in federal funds for the first three years of the program. The board will be working with New Orleans Mayor Marc H. Morial's Office of Environmental Affairs, the area's Congressional delegation and the White House to obtain the remaining $73 million in sewerage funding over the next seven years.
Managing the program
Montgomery Watson Engineers of New Orleans became involved in the city's sewer evaluation and rehab program in October 1996, after the company won a contract from the S&WB to implement the SSERP effort. Montgomery Watson Vice President Ernest Upton, P.E., said the contract covers the city's entire collection system, made up of 1,304 miles of laterals and trunk sewers, ranging in size from 8 inches to 7 feet in diameter, as well as 83 pump stations and 100 miles of force mains.
Contract terms call for Montgomery Watson to develop a computerized collection model to be used in the development of the collection system evaluation studies and remedial actions. Where possible, state -of-the-art trenchless methods are to be used for sewer repairs. Other responsibilities include managing the sub-consultants, charged with the design work on the project, and overall project management.
According to Upton, each respective basin will undergo an extensive sewer system evaluation survey, conducted by an outside consultant. The survey evaluations include smoke and dye testing, flow and rainfall monitoring, manhole inspections and surveys, and televising approximately 35 percent of the system. Sonar technology is being employed to determine the condition of surcharged sewer lines.
"Based on survey results, Montgomery Watson will determine how to fix the defects and develop construction contracts (through our sub-consultants) to get the contracts out for bid," he explained.
So far, sewer evaluation surveys have been completed in the Lakeview and Gentilly basins located adjacent to Lake Ponchartrain, the Central Business District and the city's famous French Quarter. As to surveys in the remaining seven basins, these will be conducted at a rate of one per year, with the final survey scheduled for completion in 2005. "Actual construction and remedial work in the respective basins will not be completed until 2011, so construction will be ongoing until then," Upton said.
Like most cities, New Orleans has tremendous problems with groundwater inflow and infiltration. This situation is complicated by the topography of the city, much of which is below sea level, making drainage and wastewater collection and treatment especially challenging. Every drop of rain that falls in the area must be pumped out in order for the city to remain dry. Consequently, multiple breaks have occurred in underground piping, causing the sanitary system to be overwhelmed by storm water flows.
This is evidenced by the conditions of the city's existing piping infrastructure. Upton noted that a variety of pipe materials are in place throughout the East Bank area. "We're dealing with everything from concrete to clay pipe, which are the two most predominant, although some PVC exists in areas where new gravity sewer line installations have taken place."
The Montgomery Watson spokesman said that from a corrosion standpoint the clay pipe has held up very well. At the same time, most of it is old and made up primarily of single strength Terracotta, versus the newer double strength version. "A lot of cracking and broken joints have been observed, which is typical of older clay pipe in areas where soils shift continually," he explained.
Conversely, the concrete pipe in the system was found to be suffering from severe corrosion issues, typical of concrete pipe that was in vogue 20 to 30 years ago. Upton pointed out that it's not uncommon to see an area where an entire section of the pipe has deteriorated to a point that only a hole remains in the ground. "Given these conditions, I'm surprised we haven't seen a far greater number of these areas collapse," he said.
First phase construction
In discussing current construction activity, Upton said that contractors started work in the Lakeview basin in October 1998. A good portion of these contracts cover televising 170,000 feet of existing sewer line, rehabilitating 1,900 manholes and completing 35,000 feet of trenchless rehabilitation of sewer lines. "As you can see, we are primarily focusing on manhole rehabilitation at this time. This involves anywhere from complete replacement to cementitious liners, point repairs and simply the raising of lids to match adjacent ground levels."
Upton is quick to point out that a complete review of the survey results obtained in the three basins has not been fully evaluated. "There will be additional contract awards in these areas after we've had an opportunity to fully analyze the data," he said
Specialized contractor, Video Industrial Services of Birmingham, AL, completed work in June to inspect 170,000 feet of existing sewer line. Company President John Kulbitskas said crews relied on Closed Circuit TV (CCTV) to examine the interior of sewer lines for breaks and possible sources of ground water infiltration.
"Prior to deploying the camera, each line is cleaned with a washing system made up of a 2,000 psi high pressure pump that produces 125 gpm of water to move debris out of the line and into the manhole for removal," he explained. "In this we can be certain debris or other obstructions will not prevent the camera from passing through the line."
He noted that once the line is secure the camera, mounted on a self-propelled tractor, is inserted into the pipe through the manhole. A lens on the camera pans from side-to-side and rotates 360 degrees to detect defects inside the pipe. At the same time, the images collected are recorded on video tape, along with a computer generated log of the problems detected. All the data collected is then turned over to Montgomery Watson.
In addition to the video work, two Louisiana-based contractors are completing rehab work on 1,900 manholes.
D&O Contractors of Kenner, LA, is 95 percent complete with work under a $1.1 million contract to rehabilitate 700 manholes. Project Manager Dan Wagner said crews had primarily relied on Permacast MS 10,000 cementitious liners for this work.
Prior to the installation, each manhole is cleaned with a 5,000 psi hot water pressure wash and steam. Next, the Permacast coating is applied through a spray process. "This is aerated and sprayed onto the wall until it reaches a 5/8-inch thickness," he said. "Crews then add a trowel finish, completing the cementitious lining process."
On top of that, Wagner adds, the seal from the lining on the wall to the metal casting received a Ring Seal epoxy coating. The purpose of the epoxy is to allow the castings to move up and down, expanding and contracting with the movement of the street while remaining water tight within the manhole wall structure, which is stationary and expands at a different rate.
Feucht and Sons of Eunice, LA, began work in June on a $1.5 million contract to rehabilitate 1,100 manholes in the Lakeview basin. This work will include cementitious linings, point repairs, corbel sealing, and correcting manhole lid elevations. The contract is due to be completed by January.
Boh Bros. Construction Co., LLC, of New Orleans, was the low bidder on two separate contracts, valued at $4 million, for work in the Lakeview basin. Boh Bros. Technical Director Marlin Gonzales said crews arrived in May and are currently focusing on point repairs. "There is also a significant number of house connections that will be rehabilitated using traditional digging methods, some 35,000 feet of pre-line video, sight video work and several blocks of sewer line that will be replaced using conventional methods," he said.
The next order of business will be to tackle 35,000 feet of trenchless pipeline reconstruction work on the project. This, Gonzales says, is a major undertaking due to the short time requirements of the contracts. "We've done several projects of this magnitude, in Baton Rouge, using the fold-n-form U-Liner product. That experience will be very useful in completing the Lakeview project on time," he added.
Boh Bros., who is a part owner in National Envirotech Group L.L.C., will be using the National Liner cured-in-place pipe (CIPP) method for the sewer rehab work in the Lakeview basin. National Liner has been installed in approximately one million feet of pipe throughout the United States. The method uses polyester felt, impregnated with resin that is inverted into the damaged pipe with water, then cured-in-place with hot water to the shape of the host pipe. After the new pipe has cured, lateral lines may be reopened with a remote-controlled robotic cutter.
In addition to the construction activity, design work is under way to rehab 600 manholes and 60,000 feet of sewer line in the Central Business and Gentilly District.
As to future contract lettings, Upton indicated that from this point on contracts would be put out for bid annually on rehab work in different parts of the city. Upcoming construction contacts will include Phase 2-sewer rehabilitation in the Lakeview basin that is based on the results of 170,000 feet of CCTV work recently completed. These contracts are expected to bid later this year. Also expected to bid late this year are the Central Business District manhole and sewer rehabilitation projects described earlier. Design rehabilitation efforts will also begin this year with construction contracts ready for bidding in late 2000.
Collection System Remedial Construc- End Evaluation Action tion Construc- Basin Studies Plan Start tion Lakeview -- -- 12.15.98 12.14.01 Central Business 4.1:98 11.1.98 1.1.01 12.31.05 District Gentilly 4.1.99 11.1.99 1.1.02 12.31.04 Uptown 4.1.00 11.100 1.1.03 12.31.05 Mid-City 4.1.01 11.1.01 1.1.04 12.31.06 Ninth Ward 4.1.02 11.1.02 1.1.05 12.31.07 Carrollton 4.1.03 11.1.03 1.1.06 12.31.08 New Orleans 4.1.04 11.1.04 1.1.07 12.31.09 East Southshore 4.1.05 11.1.05 1.1.08 12.31.10 Algiers 4.1.06 11.1.06 1.1.09 12.31.11
For more information circle these numbers:
CIPP 237 Manhole rehab 238 Civil engineering 239 CCTV 240
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|Comment:||Multi-Million Dollar Sewer Rehab Program In New Orleans.|
|Date:||Jul 1, 1999|
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