The Newton Falls Hydroelectric Project consists of two developments (Upper Newton Falls and Lower Newton Falls), which are located on the Oswegatchie River in the Town of Clifton, St. Lawrence County, New York. The Project is located approximately 98 miles upstream of the river’s confluence with the St. Lawrence River. The Oswegatchie River has seventeen hydroelectric projects along its length. Cranberry Lake is the principal storage facility in the Oswegatchie River basin. The Cranberry Lake Dam is located approximately 12 miles upstream of Newton Falls.
|Project Name||Newton Falls|
|LIHI Certificate Number||32|
|LIHI Effective and
|November 2, 2012
November 2, 2017
|Owner||Erie Boulevard Hydropower, L.P.|
|Location||Located on the Oswegatchie River in the town of Clifton, St. Lawrence County, New York.|
|Installed Capacity||Total: 2.22 MW
Upper Newton Falls: 1.54 MW
Lower Newton Falls: 680 KW
|Average Annual Generation||11,699,400 KWh|
|Facility Type||Upper Newton: Peaking and/or load following mode
Lower Newton: Run-of-river
Upper Newton Falls Development
The project includes a concrete gravity dam with a total length of approximately 600 feet and a maximum height of 50 feet. Components of the dam are a south non-overflow section, a post tension anchored uncontrolled concrete ogee gravity section, a four bay flood gate structure with slide gates (also post-tension anchored), an intake, and a north non-overflow section. Water is conveyed from the dam to the powerhouse via a 1,200-foot-long penstock. Along the penstock is a surge tank located upstream of the penstock trifurcation into the powerhouse.
The Upper Dam is a concrete gravity structure with a total length of approximately 600 feet and a maximum height of 50 feet. The south non-overflow section is approximately 114 feet long and forms the left abutment of the dam. The north non-overflow section is a low concrete gravity section, approximately 315 feet long, and forms the right abutment of the dam. The south nonoverflow section was refurbished in 1989 with extensive concrete repair and the construction of a new 5.0 foot high concrete parapet wall to protect the adjacent downstream backfill. The Upper Dam spillway, intake and floodgate structures are described below.
There is an overflow spillway and a flood gate structure at the project, described as follows: The Upper Dam spillway is an uncontrolled concrete ogee gravity section approximately 59 feet long with a height of 21 feet. The fixed crest elevation is 1421.0 feet mean sea level (MSL) and is licensed for 3.0-foot-high (maximum) flashboards. The upper dam spillway was rehabilitated in 1989 with the installation of post-tensioned anchors to provide additional stability and extensive concrete repair of exposed concrete surfaces.
The Upper Dam floodgate structure is a four-bay concrete gravity structure measuring approximately 42 feet by 18.5 feet with a height of 17 feet. Slide gate openings are 7 feet high by 8 feet wide with a typical invert elevation of 1410 feet MSL. This structure was refurbished in 1989 with extensive concrete repair and the installation of post-tensioned anchors to provide additional stability.
The intake is a reinforced concrete gravity structure measuring approximately 36 feet by 45 feet with a maximum height of 25 feet. The intake diverts water to the powerhouse via a penstock.
The penstock is a 9-foot-inside-diameter, 1,200-foot-long steel-banded wood-stave penstock with timber cradles on timber mud sills. The penstock was replaced in 1985. There is a surge tank on the penstock just upstream of the powerhouse. The surge tank is a riveted steel differential tank structure located upstream of the penstock trifurcation into the powerhouse. Repairs made in 1985 included replacement of the surge tank bowl (lower skin plate) and painting of the entire surge tank.
The upper powerhouse consists of a reinforced concrete substructure and brick superstructure. The powerhouse measurements are approximately 49 feet by 26 feet with a maximum height of 45 feet. Three Leffel Type “Z” turbines are housed in the powerhouse.
The development is licensed to operate in a peaking and/or load following mode with a 1-foot maximum drawdown allowed. A seasonal drawdown of 0.5-foot is required from May 1 – July 15. Generally, however, Upper Newton Falls is operated within a tenth of a foot or two of normal full reservoir elevation, although licensed for a foot of drawdown. If the pond is drawn down a foot, it may take considerable time to refill the reservoir, which could impact the base flow requirement downstream of the Lower Development (that is why it is generally limited to a fluctuation of only 0.1 foot or so). The spillway facilities for the upper dam consist of an ogee- shaped concrete gravity overflow section and four flood gates. The spillway overflow section is normally topped with flashboards. During normal conditions, flow is also discharged through a 9-foot diameter penstock leading to the powerhouse. Flows passing through the penstock were disregarded in the flood analysis. There is a downstream fish passage outlet at the right end of the spillway that passes a minimum of 20 cfs on a continuous basis.
Lower Newton Falls Development
The project includes 350-foot long, 24-foot high concrete gravity dam topped with flashboards (licensed for 3-foot), a 9-acre reservoir with a gross storage of 115 acre-feet, 300-foot bypass reach, and a one unit powerhouse with a total rated output of 680 KW at a net head of 22 feet. The normal full reservoir level is 1,374 feet (with 1.5 foot high flashboards). Components of the dam, from left to right, facing downstream, are a left embankment/corewall section, an ogee spillway with flashboards, a forebay wall, an integral powerhouse/intake, and a concrete retaining wall retaining the access/parking lot fill.
The dam is 350 feet long, and consists of a left embankment/corewall section, an ogee spillway with flashboards, a forebay an integral powerhouse/intake, and a concrete retaining wall retaining the access/parking lot fill. These components of the dam are described in more detail below.
The spillway is a concrete gravity ogee section with an overall length of 120 feet, and a maximum height of about 24 feet (28-feet to the top of the non-overflow ends of the structure). The crest is mounted with 1.5 foot high timber flashboards resulting in a top elevation of 1374 feet. The fixed crest is at elevation 1372.5 feet. It is noted that the development is licensed for 3-foot flashboards, which would allow for a full reservoir elevation of 1,375.5 feet. At the left end of the spillway is a 6-foot by 6-foot square low level outlet, controlled by a lift gate with a manual operator at the crest. The manual operator is powered by a portable drill and gasoline electric generator pair. The spillway concrete was rehabilitated in 1996.
The left embankment/corewall structure is a soil backfilled corewall structure with a length of about 125 feet and a top elevation of about 1,376.5. In 1996, a toe drain consisting of two longitudinal perforated pipes and a blanket drain were installed to remedy seepage at the toe. The forebay wall is located to the right of the spillway and serves as a training wall for the intake. It is about 80 feet long with a top elevation of 1,376.5 feet. A three foot square sluice gate with an invert elevation of 1361.5 feet exists in the forebay wall, controlled by a lift gate with a manual operator at the crest. The manual operator is powered by a portable drill and gasoline electric generator pair.
A concrete gravity retaining wall that retains the driveway to the powerhouse exists to the right of the intake, and serves as a training wall for the intake. The wall is about 88 feet long with a top elevation of approximately (estimated) 1,378 feet.
The intake is integral with the upstream face of the powerhouse. The intake structure is a reinforced concrete structure approximately 20 feet wide by 15 feet high. The intake has three bays controlled by three vertical screw stem lift gates which were rehabilitated in 2005. The screw stem hoists (one per gate) are electric. The trashracks have a clear spacing of 1 inch.
There are no penstocks or flumes at the project. The powerhouse and intake are integral structures.
The powerhouse has a concrete substructure and a brick superstructure. The powerhouse substructure sidewalls/foundation and buttresses were rehabilitated in 2006. It is a reinforced concrete structure with measurements of 30 feet by 50 feet. A single Leffel Type “Z” turbine is housed in the powerhouse. The generator unit has a rated capacity of 680 KW and operates under 22 feet of head.
The development is licensed to operate in a run of river mode with a 0.3-foot maximum drawdown below the flashboards. The top of the flashboards is elevation 1374 feet, the normal full reservoir level. The spillway overflow section is normally topped with flashboards. During normal conditions, flow is also discharged through the intake, into a passage leading to the powerhouse. Per the current license, a minimum flow of 100 cfs or inflow, whichever is less, is maintained in the Oswegatchie River below the Lower Development. This minimum flow of 100 cfs is achieved through one of two methods. The turbine in the Lower Development requires a minimum flow of approximately 146 cfs. Therefore, when there is enough flow to keep the generating unit on line, the water is passed through the unit. However, when the flow falls below the minimum turbine flow, the required flow is passed over the spillway.
December 29, 2012: The Newton Falls Project has been recertified as low impact for a second five year term, effective November 2, 2012 and expiring November 2, 2017.
February 29, 2008: The Newton Falls Project has been certified as low impact for a five year term, effective November 2, 2007 and expiring November 2, 2012.
November 1, 2007: Brookfield Power has submitted an application for certification of the Newton Falls Hydroelectric Project.