Northern Intermediate High (NIH) Pipeline

Massachusetts Water Resources Authority (MWRA)

Woburn, Reading, Wakefield, and Stoneham, MA

Stephens Associates Consulting Engineers (SA) served as geotechnical engineer for this 6.8-mile buried water main pipeline project including 3- and 4-ft. diameter pipe. The pipeline provides water system redundancy to MWRA's Northern Intermediate High service area from Spot Pond and the historic Gillis Pump Station, and allow the existing pipeline to be taken out of service for inspection and repairs.

SA performed geologic and geotechnical data review, a phased subsurface exploration program consisting of 87 borings with geotechnical soil and rock laboratory testing, and prepared several geotechnical reports with evaluation of geotechnical conditions and pipeline design and construction recommendations.

Significant geotechnical issues included extensive shallow rock to be excavated, shallow groundwater requiring dewatering, organic/liquefiable soils, nearby geologic faults, and construction considerations associated with numerous sensitive buried utilities and proximity to existing dams.