Where buildings, sidewalks and streets are closely related, or where the streets themselves are historically significant, a trench down the middle of a 300-year-old cobblestone lane causes problems. At first blush, then, trenchless rehabilitation appears ideal for towns that depend on history and appearances because trenchless rehabilitation doesn’t disturb the part of a town’s social fabric related to historic structures or activity on the surface. Are there other reasons for this belief, though?

Freedmen’s Town: A Case Study in Houston

In 2007, Freedmen’s Town, TX -- immediately west of midtown Houston — was in crisis mode. The city of Houston wanted to award a contract for open-cut water and sewer rehabilitation on lines that lay beneath its red brick streets.

Freedmen’s Town began in 1866, as former slaves moving from plantations to the east entered Houston’s 4th Ward and began to construct homes. Its streets were paved with red bricks handmade and laid by the original settlers. By the early 20th century, the collection of shanties became a thriving community of more than 1,000.

The 4th Ward ceased to be in 1906, when Houston dissolved its ward-based organization, but Freedman’s Town remained, faced with the problems of the latter part of the 20th century. As the threat of gentrification became reality, demolition claimed 72 percent of the community, but the remaining 28 percent – along with the red brick streets – gained listing in the National Register of Historic Places. (1)

When workers began the open-cut project under the original contract’s terms, the Freedman’s Town Preservation had the work with hours. (2) The Houston mayor, Sylvester Turner, said he had not authorized the projects continuation under the original terms and he would investigate other methods to achieve the same goal.(4)

High Social Cost of Open Trenches

Cities such as Boston, Seattle, Charleston and Savannah have cobblestone streets. Not only will open cut construction require the removal of the cobblestones – some of which lain undisturbed for more than 300 years – but replacement of the original stones is difficult and costly. Installing new, replacement cobblestone pavers can cost as much as $70 per square foot and destroys the historic character of the street surface. Exclusive of the other costs of the rehab project, replacement of the cobblestones on a street not more than 20 feet wide and 250 feet long would cost about $350,000.

Please don’t Disturb the Tourists

Another social cost alleviated by trenchless construction is loss of tourist dollars. Historic towns derive much of their operating cost from the presence of tourists. In the South, for example, Savannah, GA, had about 13 million tourists in 2013, representing an annual income of $2.29 billion dollars. (4) Although no extant studies pertain to loss of tourism-related money because of sewer and water line rehabilitation, it’s a logical conclusion that open-cut operations can, and will, affect tourist reactions. This makes trenchless rehabilitation the optimum choice for sewer line repair and construction in historic towns.