Sanitary and Drainage System Rehabilitation

Laconia, New Hampshire

Client: New Hampshire Department of Corrections


  • Bidding
  • Construction Administration
  • Construction Observation
  • Design
  • Evaluation
  • Trenchless Pipe Rehabilitation

Project Summary

The New Hampshire Department of Corrections (NHDOC) was under an Administrative Order from the U.S. EPA in response to findings of high bacteria (E. coli) counts and resulting beach closings in nearby Lake Winnisquam. It was assumed that the sanitary sewer system at the Laconia correctional facility was the source of the bacteria due the age and condition of the sewer and drainage system since it was constructed the late 1800’s and early 1900’s.

Based on extensive study and evaluation, Hoyle Tanner concluded that stormwater runoff from the facility grounds and not the sewer system was the source of the bacteria entering the lake. Our investigations included internal television inspection of sewer and drainage lines, dyed water testing, smoke testing, flooding and runoff simulation. Our findings and conclusions were fully supported by the New Hampshire Department of Environmental Services (NHDES).

Despite the findings, the NHDOC elected to rehabilitate the existing sewer and drainage lines due to the age and poor condition of the pipes and structures in an effort to maintain full function of the correctional facility. Trenchless technology using cured-in-place pipe lining (CIPPL) and grout sealing of pipe joints and manholes was selected in order to minimize disruption to the facilities from construction operations. One of the bidders for construction of the project proposed the use of fold-and-form pipe lining technology (trenchless) as an alternative to the CIPPL trenchless technology. After evaluation, this alternative was approved by Hoyle Tanner and the NHDOC and was successfully implemented.

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