CVPS Files for LIHI Certification for Middlebury Lower and Weybridge Hydro Projects
Middlebury Lower - east and west dams
Portland, Maine (February 6, 2012) – The Low Impact Hydropower Institute (LIHI) announced today that Central Vermont Public Service (“CVPS” or“Applicant”) has submitted an application for certification of the Middlebury Lower (“Middlebury”) and Weybridge Hydroelectric Projects (“Weybridge”).
The Middlebury Lower Project is located on the Lower Falls of the Otter Creek roughly one mile downstream from Middlebury village in the towns of Middlebury and Weybridge, in Addison County, Vermont. The impoundment extends almost 1.0 mile upstream to the Upper Falls at the center of Middlebury Village. The Sutherland Falls Project (FERC No. 2558) is located approximately 37 miles upstream, and the Beldens Project is located approximately 4 miles downstream.
Two concrete gravity dams impound the east and west river channels that diverge around a small island. The dam is 30 feet high and 478 feet long, with two ogee spillway sections, a 123-foot long western spillway section, and a 260-foot long eastern spillway section. The reservoir impounds 16 acres, with a normal water surface elevation of 314.5 feet above mean sea level (msl). The intake canal is 400 feet long, 40 feet wide, and controlled by a gate structure containing two 23-foot wide, 13-foot high gates.
The powerhouse is located at the downstream end of the intake canal, and equipped with steel trashracks having a 1.75 inch clear spacing. Three Francis turbine units provide a total installed capacity of 2.25 MW. Generator leads and transformers connect the Project to the interconnected transmission/distribution system at the switchyard located 100 feet east of the powerhouse.
Middlebury Lower Powerhouse
The Middlebury Lower Project is operated as a run-of-river facility. The impoundment elevation typically fluctuates not more than 1 inch from the crest elevation of 314.5 feet during normal operation, and water generally spills over the crest of the dam. Project operation relies upon inflows from upstream developments and the 628 square miles of the Otter Creek drainage basin.
The Weybridge Project is situated at the head of a rock-walled gorge where the Otter Creek cascades around a small island, the Weybridge Project is located in the towns of Weybridge and New Haven. The Project forms a compact cluster of buildings and structures around the divided falls at the upstream end of an island. The riverbank corridor within the Project follows the impoundment about 1.5 miles upstream to Huntington Falls (part of Otter Creek Hydro FERC No.2558), and reaches miles downstream from the powerhouse falls. The Vergennes Project (FERC No.2674) is located approximately 12 miles downstream.
The Project consists of a concrete gravity dam with integral powerhouse, a 62-acre impoundment, transmission facilities and appurtenant facilities. The dam is 30 feet high and 302.6 feet long with two spillway sections: a 150-foot long west spillway section, topped with a 6-foot high hinged steel flashboard, and abutted by a 20-foot wide and 10-foot high taintor gate; and a 116-foot long east spillway section topped with an automatically-inflated rubber weir. The reservoir is 1.5 miles long, impounding 62 acres with a normal water surface elevation of 174.3 feet msl.
Weybridge Aerial
The powerhouse is integral with the dam and has an intake with 3-inch steel trashracks. There is one vertical Kaplan turbine generator with an installed capacity of 3.0 MW. Appropriate generator leads and transformers connect the Project to the interconnected transmission and distribution system at the switchyard located about 100 feet from the powerhouse.
The Project operates as a daily cycling facility during normal and low flow conditions. cycling is suspended from April 1 to June 15 to protect fish spawning. The Project operates in a run-of-river mode when flows exceed its hydraulic capacity of 1,600 cubic feet per second. A diversion structure extends from the downstream end of the dam at Rock Island to another small island at the entrance to the bypass channel, and around another island (Wyman Island), reapportioning the flow in the bypassed (west) and tailrace (east) channels. The diversion structure includes a control weir with stop log slots at the downstream end, at the entrance to the west channel. A 15-foot wide by 3.5-foot high notch in the control weir passes water from the pool formed by the control weir and the diversion structure, downstream into the west channel around Wyman Island.
Public Comments
We encourage public comments on this application. Specifically, we are interested in knowing whether you think this Project meets our LIHI criteria. Review the program and criteria in greater detail and then review the Project’s application. Comments that are directly tied to specific LIHI criteria (flows, water quality, fish passage, etc) will be most helpful, but all comments will be considered. Comments may be submitted to the Institute by e-mail at info@lowimpacthydro.org; or by mail addressed to LIHI, 34 Providence Street, Portland, ME, 04103. Comments must be received at the Institute on or before April 6, 2012 Eastern time to be considered. All comments will be posted to the web site and the applicant will have an opportunity to respond. Any response will also be posted.