Problem

Ecotone LLC , an environmental construction management firm, was working a term contract in Baltimore County, Maryland. They needed to rehabilitate 96 linear feet of corrugated metal pipe. The challenge was that the twin 72” pipes passed under a county road that accesses an apartment community’s main office, and beneath the swimming pool amenity for the entire community. The pipes had suffered extreme deterioration from prolonged exposure to constant running creek water. They now evidenced advanced deterioration and small voids, creating pipe failure concerns.

The single point of access to the main offices, ruled out the traditional dig-and-replace method as a viable option, due to potential life safety impact with limited access by fire and emergency medical services. Open cut was also ruled out because an existing playground directly adjacent to this site presented dangers to children there. Unfortunately, this latter concern also ruled out several potential trenchless methods.

Solution

Pleasants Construction, Inc., won the project, bid as a $250,000 cured-in-place-pipe (CIPP) lining job using the Alphaliner 1800H UV-cured liner system. There were two segments of 72-in. CMP, each 48 ft. long, to be lined.

Logistics challenges included that the creek ravine containing the pipes was located between the roadway and a CSX railway track. This culvert area was protected by a fence and was overgrown with weeds. This situation required some cut-in of a temporary work area for equipment and the liner crate, plus crew access. The crew also had to create an area to build their sandbag weir and to accommodate diversion for bypass pumping. Though an excessive rain event occurred the afternoon/evening before the install, no issues or delays were caused by the storm, thanks to proper site precautions taken by the crews.

The installer was able to meticulously clean and televise the pipes in preparation for the lining process. They spent the first day performing a televised line inspection and bringing in their hydro-vac truck to pressure wash and clean out the pipes. A second day was spent clearing debris and prepping the pipe’s interior surface. During preparation, crews were diligent in the safety of the general public and community, which showed curiosity about the ongoing work.

The weight of these resin-impregnated liners required a 40-ton crane to lift the liner crates off the truck and assist in setting them down in the crews’ work area. Crews successfully pulled the Alphaliner product into place, and introduced air into the liner for expansion into the failing host pipe. With less than 8% elongation, the Alphaliner glass reinforced pipe product was a perfect solution for this project. Using the Reline America REE4000 Curing Unit, the liner was successfully cured in place without any impact to the surrounding community or existing creek flows.

Each pipe required a full day for installation and curing. A second day allowed for quality control testing and site remediation back to its former state. Throughout this process, bypass pumping was provided by the construction manager.

Within 48 hours of crews arriving on-site, the pipes were rehabilitated and returned to service without any trenches or open-cut excavation.

Result

Possible structural concerns, now and in the future, have been eliminated with the installation of the Alphaliner 1800H structural liner. Due to the success of the project with such limited disruption to the community, the local municipality has been utilizing UV GRP lining on a number of problematic lines throughout other parts of the county, as well as the continued use in corrections to stormwater assets and failing outflow lines.