At the public meeting this Wednesday on the Soapstone Valley sewer rehabilitation project, at least one member of the community will be asking the National Park Service and DC Water if the work has to be so invasive.
As described on page 6 of Appendix E, Statement of Findings:
Approximately 6,100 [linear feet] of sanitary sewer pipe infrastructure within the Soapstone Valley sewer system would be rehabilitated using trenchless technology…. Cured-in-Place Pipe (CIPP) is a trenchless rehabilitation technology that involves the insertion of a resin-impregnated felt lining inside the existing, or host, pipe. This lining is then cured in place using either water or steam…. With this technology, most construction activity occurs at existing manholes. Given the site constraints in the study area, construction of access paths to certain manholes would be necessary.
The Statement of Findings goes on to state that paths will be required for heavy equipment access. They will be 16 feet wide, but at some locations, the paths will be wider than 20 feet to allow for maneuvering the equipment.
Marjorie Share, a member of the ANC 3F Parks & Trails Committee, is particularly concerned about the heavy equipment pathways and the resulting loss of as many as 371 trees. (See page 26 of the the environmental assessment, “Impacts of Alternative 2”)
She knew there had to be a better way. She started digging and came across Ultraviolet Cured-in-Place Piping (UV CIPP), or UV curing. This technology does not require the heavy equipment that the steam and hot water curing method does, and thus has a much smaller footprint in hard-to-reach areas like Soapstone Valley. It can also also be a cheaper technology. It is more expensive to do the clearing for the heavy equipment that the steam and hot water method requires.
UV curing was the method used to reline a sewer main in Medicine Lake, Minnesota. The project was led by SEH, an employee-owned engineering, architectural, environmental and planning company in Minnesota that works on infrastructure projects.
Share contacted Dave Hutton of SEH for more information. I was invited to join the conversation.
Hutton told us UV curing technology has been used in the states for about 10 years and in Europe, about 20 years after it was developed in Germany. It has taken a lot longer for the U.S. to embrace this as a go-to trenchless (which means not digging up pipes to replace them) technology.
Hutton said the Medicine Lake project involved sewers situated between the lake and people’s homes, “so it would have been pretty much impossible to get the steam/hot water equipment back to the manholes,” Hutton said. “The UV cure method and equipment was a great solution to line the sewers in this very difficult conditions. It was the first UV cure liner used for a City in Minnesota and I was very impressed with the technology and process and would definitely consider using it again with the right project and circumstances.”
J.C. Dillon of Peoria, Illinois was the contractor SEH used for the Medicine Lake project. Hutton told us there about 10 companies around the country that do this work.
The public meeting on the Soapstone project will be held on Wednesday, June 26th, 6 to 8 p.m. at the Forest Hills of DC Assembly Hall (4901 Connecticut Avenue). Marjorie Share and others will be eager to hear whether UV curing or other new technologies could be used in the Soapstone Valley.