The Sugar River No. 1 Hydro Dam consists of a 175-ft long and 16-ft high Ambursen-type slab and buttress concrete dam with 2-ft flashboards and is operated as a run-of-the-river facility. Following a request from FERC, the Sugar River Hydroelectric Power Company engaged D&K to complete an Emergency Action Plan for this facility. Staff visited the site to evaluate existing conditions and operational requirements of the dam; reviewed existing inundation mapping and breach analysis; completed an Emergency Action Plan and coordinated with the Owner and FERC; and conducted a phone call-level verification test of the Notification Flowchart. Based on this test and owner comments, D&K completed and submitted a final EAP.
Dam Safety and Surveillance Monitoring Plan (DSSMP), Enel Green Power
D&K updated the Dam Safety and Surveillance Monitoring Plan (DSSMP) for a 390kW 30-ft-high run-of-the-river hydroelectric dam (FERC No. 5261-VT). D&K reviewed the existing DSSMP for the facility; participated in a site visit with facility staff to complete the revised first quarter checklist; and reviewed existing data including FERC correspondence, plans, Dam Safety and Surveillance Monitoring Reports, Potential Failure Mode Analysis report, FERC Part 12 inspection data, and Supporting Technical Information Documents.
Low Level Outlet Repair, Enel Green Power
DuBois & King designed structural repairs to the existing low level outlet structure at the Hoague-Sprague/EHC Hydro Plant (FERC No. 4337-NH) on the Contoocook River to return the structure to a sound and watertight condition. The low level outlet structure is adjacent to the right abutment of an existing rock filled timber crib dam. D&K’s scope of work for this project includes a visit to the site, providing preliminary design, incorporating the owner and FERC’s comments on the design, and completing a final design package suitable for bidding and construction.
Dam Safety and Surveillance Monitoring Reports (DSSMR), Enel Green Power
DuBois & King prepared Dam Safety and Surveillance Monitoring Reports (DSSMRs) for four hydroelectric projects in Barnet (FERC No. 5702-VT), Newbury (FERC No. 5261-VT), and Sheldon Springs (FERC No. 7186-VT), Vermont; and Woodsville (FERC No. 5307-NH), New Hampshire. D&K reviewed available drawings and data for each project, visited the project sites, completed quarterly inspection checklists in accordance with Dam Safety and Surveillance Monitoring Plans (DSSMPs) and prepared a DSSMR for each facility.
Bolton Falls Penstock Condition Assessment
DuBois & King provided a FERC-level inspection and condition assessment report of the existing penstocks at the Green Mountain Power Bolton Falls Hydroelectric Facility located on the Winooski River. The facility consists of an intake structure, two 10-ft diameter welded steel penstocks encased in concrete, two horizontally mounted tube turbines with fixed blades, two generator units, a powerhouse, and a tailrace structure.
The penstocks were visually inspected from the intake structure to the beginning of the scroll case; the combined length of both penstocks is 264 lf. Inspection consisted of visual observations, a visual coating survey, shell thickness readings using an ultrasonic thickness gage, and shell soundings. Portions of the penstocks were inspected using rope access due to a 33 degree inclined section.
A condition assessment report was prepared subsequent to the inspection. This report documented the inspection activities and provided a summary of collected field data, stress analysis calculations, and recommendations.