Relining on a Grand Scale
A year-long rehab project is winding down in Baltimore County, Md., which involved relining more than 38,000 ft of large diameter pipe — a project that its contractors say may be the largest cured-in-place pipe (CIPP) sanitary sewer project to date in the United States.
The $23.2 million project — called the Patapsco Interceptor and Relief Sewer Rehabilitation Project — involved four phases of bypassing and relining two aging sewer interceptors, ranging in diameter of 42 to 72 in., located along the Patapsco River in Patapsco Valley State Park, which extends along 32 miles of the river. The park is a popular destination for hiking, fishing, camping, canoeing, as well as horseback, mountain bike and ATV trails.
“We believe that this may be one of, if not the largest CIPP projects in the United States,” said Gerhardt Rodenberger, Spiniello Companies division manager-CIPP. “This project required a tremendous amount of preplanning and scheduling. We are proud to say that the project was performed on time, with an excellent worker safety record and with zero bypass system failures.”
Baltimore County has been working with and has been under a consent decree by the U.S. Environmental Protection Agency, U.S. Department of Justice and the Maryland Department of the Environment to rehabilitate its existing and relief interceptors to reduce inflow-and-infiltration into its system. Both interceptors run parallel to each other along the Patapsco River on the border of Howard and Anne Arundel counties and extend to Baltimore County’s Patapsco Pump Station. The interceptors were subject to severe groundwater infiltration and inflow from the river during high rain events, resulting in the considerable flooding, as well as damaging manholes and creating sinkholes.
“The river would actually flood over into the sewer. Some of the manholes had holes in their sides and there were some sinkholes over top of the sewers, as well as holes in the sewers,” said Rodenberger. “During flooding events, the water was just flowing right into the sewer and overwhelming their system.”
Each interceptor runs 18,000 ft. The original interceptor (now used as the Relief Interceptor), was made of concrete and clay and is a combination of 42- and 48-in. diameter pipe. The 70-year-old sewer was in poor condition, with joints open and pieces of pipe eroded away and missing. The Patapsco Interceptor is made of concrete and is a combination of 54-, 66- and 72-in. diameter pipe. Constructed during the 1980s, this pipe had sustained severe joint issues during its lifespan. The project also included the rehabilitation of 75 brick manholes that had deteriorated over the years.
The Baltimore County Department of Public Works retained URS Corp. to assess and evaluate the current structural condition of these interceptors, beginning from the intersection of I-895 and I-95 to the Pump Station, and perform a hydraulic analysis of the system, as well as design the rehabilitation for the Patapsco Interceptor and Relief Sewer. CCTV inspection of the interceptors revealed that the Relief Interceptor was in multiple stages of failure, with a number of open joints and cracks existing throughout the pipe, as well as several areas of broken and missing pipe. These conditions allowed moderate to high volumes of infiltration to enter the system. The Patapsco Interceptor was in better shape but still was in need of rehabilitation.
As a result of extensive field investigations and review of applicable trenchless methods, URS recommended CIPP lining of the pipes. URS also recommended complete interior and exterior rehabilitation of the manholes along the route, including raising the manholes above flood level and installing new watertight frames and covers.
The investigation and design activities proved to be challenging due to the project site’s remoteness and the permitting process. Permits had to be negotiated and acquired from sources such as the U.S. Army Corps of Engineers, Maryland Department of the Environment, CSX, AMTRAK, U.S. Fish and Wild Life Services, among others. Permits also included restrictions on Spiniello to allow resident bald eagles to nest in the park undisturbed.
“After the county approved the design recommendations, we proceeded with the design phase, which proved to be a long and challenging one,” said Pedro Ramirez, P.E., URS Corp. “Numerous agencies have jurisdiction over the project area. In all, 18 permits needed to be secured and very close coordination was needed to get all the agencies to approve the permits.”
URS faced several challenges in the design of this project, with the biggest being the extreme remoteness of the project site. Aside from the accessibility, URS also had to address the site being located in an environmentally sensitive wetlands area, as well as the heavy overgrowth that had built up over the years. Also, there was a 2,000-lf section of pipe that was virtually inaccessible due to a low railroad overpass at one end and a creek at the other.
All these challenges had to be resolved and reconciled in the design process to protect the wetlands, gain access to the interceptors and construct bypass stations to keep flow going to the pump station for the project’s duration. Pre-planning would be a critical component of success for whichever contractor was awarded this project.
The project was put out to bid in August 2008, with four major players in large diameter CIPP work submitting bids. Spiniello Companies was awarded the project a month later. Spiniello is a contracting company that prides itself on being one of the leading large diameter CIPP companies in the United States, being able to handle whatever the project calls for and completing it on time. When company officials saw the project details, they knew they could more than handle the strict schedule and project parameters.
“Spiniello Companies has been around since 1922 and we do all sorts of rehab work, such as CIPP, sliplining, pipebursting, as well as CIPP of potable watermains and the traditional cement mortar lining of water mains,” Rodenberger said. “As a general contractor, we like to handle most of the work, if not all of it, by ourselves. For this project, we realized after reviewing the site and project challenges that the best way for us to succeed was to do the entire project ourselves, instead of subcontracting portions of it.”
One of the primary design concerns was gaining access to the site. URS had to design the project in such a way that the remote access and the strict permit restrictions wouldn’t impede the contractor’s progress. One of the design features URS came up with to protect the designated wetland area was the use of reusable wooden mats to build access roads. Additional permitting requirements limited the width of the access roads to 16 ft; the wooden mat road design allowed the contractor to meet this requirement while safely allowing the heavy construction equipment and materials to be transported to and from the site.
“The intent of the project was to preserve as much of the natural habitat as possible and utilizing wooden mats would prevent any damage to the wetland grounds,” said Rodenberger. “Before we could construct the access roads, we had to clear out the brush and small trees.”
The wooden access road consisted of laying down stone filter fabric and woodchip bedding and then the portable wooden mats, which were 6 in. thick, 8 ft long and 15 ft wide. Each mat weighed 3,000 lbs. “Instead of building the entire road at once, we decided to build the road as we were going, always staying ahead of ourselves,” Rodenberger said. “As the train of our lining operation is moving down toward the next phase, we would pick up the mats behind us and use them in the next phase.”
“During the construction phase, I would say that the most challenging aspects of the project were the tight deadline, which necessitated round-the-clock work both onsite and at the liner production plant and the bypass of the existing flows, as the system carries a peak wet-weather flow of over 70 million gallons a day,” Ramirez said.
URS designed the 38,000 ft of CIPP work to be done in four phases, each necessitating construction of a bypass station that would handle the simultaneous diversion and bypass of 80 million gallons a day (MGD) of sewage flow during the project’s duration. Considering the length of the project, the bypass was to be installed, operated and moved downstream during the four phases, similar to the access road construction. Also, access to traditional water sources was next to impossible due to the site’s remoteness. URS’ answer to this challenge was to secure permits to use water from the Patapsco River for construction-related activities, such as cleaning and liner inversion.
“Each bypass was roughly 6,000 lf long. Since the project had two parallel lines, we were able to divert roughly 30 MGD into one system, while bypass pumping 50 MGD aboveground,” said Rodenberger. “This bypass pumping and diversion required a lot of coordination and planning between all of us to make sure that everyone could work in the proper environment at the times needed. The lining and manhole rehab of inverts had to be done dry while the manhole risers and cleaning could be done with flow. It was critical to provide everyone what they needed, all within a work zone laid out within the bypass phase and temporary road phase.”
To handle the bypass, Spiniello utilized six Godwin Pumps CD400M 18-in. Dri-Prime pumps and three of Godwin’s CD300M Dri-Prime 12-in. pumps. Rodenberger said that Spiniello had planned to handle the bypass work itself — from setup to monitoring to moving the equipment to the next phase. However, due to the pace the project needed to maintain and the amount of work involved (including fusing two sections of 14,000 ft of 24-in and 18-in HDPE), Spiniello re-evaluated its plans and decided to bring Godwin personnel into the project to handle the relocation of the bypass system.
“With the vast amount of HDPE that needed to be fused and given the workload on our crews for this project with the access roads, lining and site restoration, as well as several other projects across the country, it just made sense,” Rodenberger said. “That way, they could assist with moving and setting up the bypass system to each phase while we were lining and restoring. It would help compress the schedule.”
The CIPP runs were divided into four phases, with each phase taking approximately eight to 10 weeks, depending on how many inversions were needed. Phase I involved 9,000 ft (4,300 ft of 48-in. and 4,600 ft of 54-in.), with the longest shot being 1,700 ft. Phase II involved 10,200 ft (5,500 ft of 42-in. and 4,600 ft of 66-in.), Phase III involved 8,900 ft (1,530 ft of 42-in., 3,200 ft of 48-in. and 4,200 ft of 66-in.) and Phase IV involved 9,500 ft (3,800 ft of 48-in., 5,500 ft of 66-in. and 240 ft of 72-in.).
Spiniello manufactures its own liners at its Ambridge, Pa., facility from the raw felt sheets supplied by Applied Felts. “Spiniello has been manufacturing its own liners for more than 18 years. We knew that having complete control of the build process would ensure that we could deliver liners to the site on time, while maintaining deliveries to our other crews around the country,” Rodenberger said.
The liners were loaded on a flatbed and delivered directly to the site. The liner was then fed onto a conveyor belt at the manhole and the resin (supplied by AOC) was pumped directly into it; the liner was then inverted into the pipe. Once installed, the boiler trucks were brought in and, using hot water, the liner was cured. “The size of the pipes in this system resulted in the liners being too heavy to be safely transported so all of the liners were wetted out onsite, making as many multiple pipe segment runs as possible. Segments of more than 1,700 lf of pipe were routinely lined,” Rodenberger said.
The manholes were rehabbed, using Sauereisen products, right along with the lining, with 75 done in total. Spiniello’s work was pretty much completed by October 2009, with just a small section of 72-in. pipe still to be rehabbed after rehab work to the pump station is finished.
“Baltimore County should see a huge reduction of inflow because of this project — between the relining and manhole rehab, this pretty much locks up this area,” Rodenberger said.
For Baltimore County, this project marked a number of firsts — size, scope, cost and onsite wetout. “We’ve done sewer relining before, but it’s all been much smaller diameters, usually 8 to 16 in.,” said Vincent Kicas, chief of the division of construction contract administration with the Baltimore County Department of Public Works. “The size of this project was huge for the county to undertake. It’s also the first [CIPP] project we’ve had where they have done the impregnation of the liner onsite.”
Kicas added that Baltimore County is more than pleased with the project’s outcome. “It went great and everything got done on time,” he said. “Spiniello was a great company to work with.”
Sharon M. Bueno is managing editor of Trenchless Technology.