December 10, 2018: The Low Impact Hydropower Institute has received a complete application for Low Impact Certification of the Pownal Hydroelectric Project (FERC No. 6795, exempt). The Project is located on the Hoosic River in the in the town of Pownal, Bennington County, Vermont.
LIHI is seeking public comment on this application. Specifically, we are interested in knowing whether you think the Project meets the LIHI Low Impact Certification Criteria, as revised in the 2nd Edition Handbook. Please review the program and criteria in LIHI’s revised Handbook and then review the Project’s application materials below.
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 email@example.com with “Pownal Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 329 Massachusetts Avenue, Suite 2, Lexington, MA 02420. Comments must be received on or before 5 pm Eastern time on February 8, 2019 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.
The Pownal Hydroelectric Project (Project) is located at the former Pownal Tannery Plant on the Hoosic River in Bennington County, Town of Pownal, Village of North Pownal, Vermont along State Route 346. The Town of Pownal is located in the southwestern most region of the State of Vermont approximately 30 miles from the New York State boarder and the watershed extends into Massachusetts. The Project is located at river mile 38.6.
|Owner||Hoosic River Hydro|
|Location||River mile 38.6 on the Hoosic River|
|Installed Capacity||0.491 MW|
|Average Annual Generation||3,200 MWh|
|Facility Type||Run of river|
|FERC No.||6795 (exempt)|
The Pownal Project includes a single vertical turbine which produces a maximum output of 491 kW and the Project operates in instantaneous run-of-river mode with no ponding or storage. A minimum flow of 56 cfs is maintained in the bypass reach and ramping rates of 0.1% per second (21 cfs/minute) are maintained. Ninety percent of instantaneous flow is released downstream during impoundment refills if the impoundment is drawn down below 516.6 MSL.
Significant project features include a concrete overflow spillway with flashboards, an intake canal, forebay, a 93-foot-long penstock, powerhouse and tailrace. The dam consists primarily of an ogee gravity overflow structure built in 1955. The dam is 153 feet long, has a maximum height of 18 feet and a crest elevation of 513.91 feet MSL. The dam operates with 2.5 feet of flashboards and crest gate combination with a normal water surface elevation of 516.60 feet MSL. The impounded area extends approximately 2.5 miles upstream of the dam creating a reservoir with a normal storage capacity of 490 acre-feet and a surface area of 77 acres.
At the right abutment of the dam, there is an intake canal (40-foot-long concrete overflow section). The canal is 20 feet wide and approximately 18 feet deep relative to the crest of the dam. A 93-foot-long, 8-foot-diameter penstock conveys water from the forebay to the powerhouse. The wood frame powerhouse includes a Wasserkraft turbine and Hitzinger induction generator pair with a capacity of 491 kW at 20.5 feet of gross head. The power at the turbine shaft is 700 HP. The maximum hydraulic capacity of the unit is 350 cfs. The turbine flow ranges from 66 to 350 cfs, but the current environmental requirements stipulate a low-end flow of 110 cfs. The Project received a FERC exemption and a Water Quality Certificate (WQC) in 1983. Following issuance of these documents, the project was constructed; however, in 1988 operations ceased due to a catastrophic equipment failure. The Town of Pownal, Vermont acquired the rights and FERC exemption for the site through involuntary acquisition due to non-payment of taxes. In 2013, Hoosic River Hydro (HRH) entered an agreement with the Town to revitalize the hydropower. On March 6th, 2014 FERC recognized HRH as acting agent for the Exemptee under an Option Agreement with the Town. HRH has since exercised that Option to lease and operate the Plant and, effective March 29, 2018, is now the Exemptee for the Plant.
The site is enrolled in both the EPA Superfund Program and the EPA Brownfields Program due to historical contamination. The Superfund program focused on land-based contamination and the Brownfields program focused on wetlands-based contamination at the Project. The primary remediation efforts related to the hydropower development focused on PCB-contaminated sediment upstream of the dam. As of 2017, all contaminated sediment that would be mobilized by the operation of the Project has been properly removed from the site or mitigated with close oversight from VTDEC and US EPA.