Making Way for More Power
Public Service of New Hampshire (PSNH) had plans for the design and construction of a new 45,000 square foot, 115-kV transmission substation adjacent to an existing substation. An existing access road through the new substation area had to be relocated to maintain continuous access to PSNH’s generation coal yard. A 10-foot grade difference between the two substations, and the relocated access road, required approximately 11,000 cubic yards of material removal and handling. It also required construction of an approximate 430-foot-long retaining wall.
Exploration & Cost Savings Get Underway
As part of this project, Tighe & Bond conducted a combined geotechnical and environmental subsurface exploration program. Based on the results of the environmental assessment and evaluation of soil management options, the site design was altered to raise the foot print of the substation, minimizing the volume of soil required to be managed offsite, resulting in a $500K project savings.
Geotechnical services included a preliminary assessment of the subsurface conditions and suitability of the site for the new substation. We also provided final evaluations and recommendations for foundation support of new transmission equipment and structures, as well as the retaining wall and relocated access road. Geotechnical implications on site design and construction were identified, and incorporated into the project construction documents.
Our scope of services included site design, local and state permitting services, wetland delineation services, preliminary and final geotechnical evaluations, soil pre-characterization and soil management. Other services included preparation of construction drawings and specifications, as well as a stormwater pollution prevention plan (SWPPP).