Upstream of dam

Upstream of dam

The Alternatives Project is located on the Mumford River in the Town of Northbridge, Village of Whitinsville, Massachusetts.  The Mumford River is a tributary of the Blackstone River with a watershed of about 335 square miles in Massachusetts and 258 square miles in Rhode Island. Land use within the Blackstone River Basin is primarily forest and residential. The area around the project was historically comprised of industrial and urban development. The Town of Northbridge, home to the historic Whitinsville Historic District and corresponding mill complex, surrounds the Mumford River and the proposed project site. Elements of the historic mill and forge building complex remain in the project vicinity.

Project Name Alternatives
LIHI Certificate Number 50
LIHI Effective and Expiration Dates January 19, 2015
January 19, 2020
Owner Alternatives Unlimited
State Massachusetts
Location Located on the Mumford River in the Town of Northbridge, Village of Whitinsville, Massachusetts.
Installed Capacity
Average Annual Generation
Facility Type Run-of-river
FERC No. 12608

The Project Dam is called the Ring Shop Dam.  The dam drains approximately 48 square miles with an average annual flow of 44 cfs.  It impounds 2 acres and stores 16 acre-feet at proposed pool elevation of 285.1.  Without the flashboards (at pool elevation 282.6), approximately 1.3 acres are impounded or approximately 700-linear feet.  The height of the dam from its toe to the top of its abutment is 15.5-feet.  The spillway height is 9.5 feet and the normal hydraulic head on the structure, with 30-inches of flashboards installed, is 12-feet.

The Project consists of a 93.5-foot concrete ogee spillway, a waste gate, and two inlet structures located at the north and south ends of the spillway.  The ogee crest is fitted with sockets to accommodate 2½ inch pipes, 30-inches tall on three-foot centerlines.  The crest is designed to be fitted with 30-inch tall flashboards.  The crest elevation is 282.6 (282.0 msl original datum). The deeded water rights allowed the impoundment to be raised to 285.1 (284.5 msl original datum) with the flashboards installed.

The dam was originally constructed to impound and convey the waters of the Mumford River to the shops of the Whitinsville Machine Works constructed on both banks of the river.  Both intakes are now abandoned.  The turbine generator sets for the northern intake were removed in the 1980s when the shop was converted to an assisted living facility.  At that time, the intake canal was sealed off and the hydro power was abandoned.  The Machine Works Shop is now occupied by Cotton Mill Apartments, an assisted living complex on the downstream side of Douglas Road.

The southern intake was abandoned at the turn of the century.  It consists of a silted forebay, which leads up to a wooden headgate.  This gate is located beneath the lower Alternatives Building.  The top of the headgate is visible in the silt and has slid sideways.  Under prior conditions, the water was conveyed through a short five-foot diameter stub penstock to a turbine casing located beneath the same building.  An existing tailrace conveyed the water back to the Mumford River just upstream of the southerly abutment of the Douglas Street Bridge.

The original timber crib dam was destroyed in a 1938 flood and was replaced in its entirety in 1941 with a concrete gravity structure.  It was originally proposed to reconstruct the existing southern forebay, intake gate, discharge pit and tailrace and install the turbine in the approximate location of the former hydro equipment.  However, due to the deterioration of the existing hydro-infrastructure, the turbine was installed outside the building, on the south side of the dam, just downstream of the flood-gate opening.  The power unit is one (1) 47 kW Leroy Somers Tube Turbine, which has a hydraulic capacity of 70 cfs.  The expected plant factor is 82%.  It is anticipated that all generated electricity would be utilized by Alternative’s facility, except during low power demand, when net metering will occur.  Massachusetts Electric Company provides transmission at the site.

The Project is to be operated strictly “Run-of-River” and the outflow will equal inflow. No “Peaking” or “Ponding” will occur.  The unit will be equipped with a pond leveling device to accurately match the turbine discharge with flow conditions.  The units will drop “off-line” and the turbine gates will close automatically should flows drop too low for efficient operation.  Further, all minimum stream flows will be maintained as required by the agencies.  The units will be semi-automatic; they will be started up and put “online” manually and will shut down under all fault or low flow conditions.  The Trashrack provided is a 20-foot long (1/4-inch x 3-inch flat stock), with clear spacing of 3/4-inch and 45º angle to flow as designated by the U.S. Department of the Interior and MA Department of Fish and Wildlife.

downsream of dam

Downsream of dam

Looking Northeast and downstream

Looking Northeast and downstream

Certification History

December 14, 2015: LIHI Executive Director Michael J. Sale, using authority delegated from the LIHI Governing Board, has certified that the Alternatives Hydroelectric Project (FERC No. P-12608) continues to satisfy the LIHI Certification Criteria. A Preliminary Decision was announced on November 8, 2015, and a 30-day appeal period was open through December 8, 2015. No requests for appeal were received.

The effective certification date for the Alternatives Project is January 19, 2015 for a five (5) year term, which will expire on January 19, 2020.

The reviewer’s report can be found in the Files section below.

July 10, 2015: The Alternatives Hydroelectric project has been granted an extension of the current certificate term. The new expiration date is December 31, 2015. See ExtensionLetter_20150709 for explanation below.

June 23, 2015: The Low Impact Hydropower Institute received a comment letter from Caleb Slater, of the Massachusetts Division of Fisheries and Wildlife, in support of the recertification of the Alternatives project. The letter can be read in the Files section below.

May 18, 2015: The Low Impact Hydropower Institute received a complete application for a new term of Low Impact Certification for the Alternatives Hydroelectric project on May 18, 2015.  The application materials can be found below in the Files section.

April 9, 2015:  The Alternatives Hydroelectric Project has been granted a six month extension of the current certification term.  The new expiration date is July 18, 2015.  See April 2015 Letter Extending Term and Explaining Recertification below.

April 21, 2010: The Alternatives Hydroelectric Project has been certified as low impact for a five year term, effective January 19, 2010 and expiring January 19, 2015.

January 19, 2010: Alternatives Unlimited has submitted an application to LIHI for certification of the Alternatives Hydroelectric Project. Comments concerning the certification of the project can be submitted up until March 19, 2010.


Files: