New Powerhouse

The Holtwood Project is located on the Lower Susquehanna River at approximately River Mile 25 in Lancaster and York Counties in south-central Pennsylvania as shown in Figure 1.  The Project is situated approximately seven miles north of the Pennsylvania/Maryland border, and is one of five hydroelectric projects located along the lower Susquehanna River.  Four of these projects are mainstem dam projects and one (Muddy Run) is a pumped storage station that uses the Conowingo Pond as its lower storage pond.  Moving from downstream to upstream, these Susquehanna River hydroelectric projects are: Conowingo, Muddy Run Pumped Storage Project, Holtwood, Safe Harbor, and York Haven.

Project Name Holtwood
LIHI Certificate Number 116
LIHI Effective and Expiration Dates January 20, 2014
January 20, 2022
Owner PPL Holtwood, LLC
State Pennsylvania
Location Located on the Lower Susquehanna River at approximately River Mile 25, in Lancaster and York counties in south-central Pennsylvania.
Installed Capacity 252 MW
Average Annual Generation From October 2006 through September 2011, 590,043,642 kWh
Facility Type
FERC No. 1881

The Holtwood dam is an overflow-type structure that consists of a 2,392 ft long by 55 ft high, low hazard, concrete gravity dam with a spillway crest at El. 165.0’.  The top of the dam is raised to an effective elevation of 169.75 ft via the use of wooden flashboards and inflatable rubber dam sections.  The dam forms an approximately 8-mile long reservoir, Lake Aldred, with a surface area of approximately 2,600 acres at maximum water level.  A skimmer wall located on the upstream side of the forebay protects the powerhouse from debris.  The forebay is being expanded and the skimmer wall is being replaced as part of the redevelopment project.

Downstream of the dam, a diversion wall connects the western side of the original powerhouse to a long, narrow river island known as Piney Island, and effectively separates the tailrace from the remainder of the Susquehanna River.  Along the western shore of Piney Island, another narrow channel is formed between Piney Island on the east and a series of smaller islands on the west; this channel is referred to as Piney Channel.  Excavation in both the tailrace and Piney Channel is underway to reduce backpressure on the generating units and also to improve fish passage.  The remainder of the Susquehanna River bed is referred to as the spillway.

The Project powerhouses, including the original powerhouse constructed between 1905 and 1910 as well as the new powerhouse that is currently undergoing construction, are located on the east side of the river along the Lancaster County shoreline.  The original powerhouse contains ten similarly-sized vertical Francis turbines, with a total combined hydraulic capacity of 31,500 cfs.  The original powerhouse also contained two smaller, and retired, exciter units; PPL Holtwood, LLC is replacing those with two 1.18-MW vertical Francis turbine generator units as part of the redevelopment.  The new powerhouse will contain two 40.3-MW vertical Kaplan turbine generating units with a combined hydraulic capacity of 30,500 cfs.  All water entering the powerhouse goes to the tailrace with the exception of the westernmost generating unit in the original powerhouse, Unit 1.  PPL Holtwood, LLC has rerouted its draft tube so that it flows into Piney Channel.

The fish passage facilities at Holtwood include a tailrace lift with two entrances and a spillway lift for upstream passage, and a pipe built at the west side of the powerhouse for downstream fish passage and debris sluicing.  The two upstream lifts have their own fish handling systems that sluice fish into a common flume through which fish swim into Lake Aldred.  The lifts or “hoppers” raise the water (and fish) entering the facility about 50 feet to the level of the forebay.  Fish swim through the flume and enter the lake outside the plant skimmer wall.  PPL Holtwood, LLC is reconfiguring the existing fish lift to improve migratory fish passage.

At the western end of the dam is a non-functional fish ladder that was constructed in 1914.  At that time fish passage technology was immature and the facility was never successful in passing American shad.  The facility was abandoned in place around 1920.  PPL Holtwood, LLC is installing new whitewater features immediately below this area.

Certification Benefits

The Holtwood certification achieves LIHI’s dual goals of energy and environmental benefits, with an estimated average annual generation of 1,014 GWh of clean and renewable electricity, plus these environmental enhancements:

  • improved releases downstream of the dam for aquatic habitat enhancement, attraction of upstream-migrating fish, and recreational uses;
  • new fishways for upstream fish passage and downstream fish protection;
  • extensive monitoring of flows, water quality, and fish movements, with results to be made accessible and understandable to all stakeholders on an annual basis and used in a standards-based adaptive management program to measure and improve project performance over the next decade or more;
  • active management of endangered species and other sensitive species in the project area, including bald eagle, osprey, great blue heron, and plants; and
  • enhanced whitewater boating access and facilities that did not previously exist.

 

Existing Powerhouse and Dam

Certification History

June 23, 2014: The Holtwood Hydroelectric Project is certified as low impact for an eight year term, effective January 20, 2014 and expiring January 20, 2022.

The Holtwood Hydroelectric Project certification includes two (2) non-standard conditions, as follows:

 

  1. In its annual compliance statement to LIHI, PPL-Holtwood shall provide LIHI with a copy of the Fish Passage Technical Advisory Committee Report, developed in accordance with FERC License, Article 55, which describes the status of all fish passage and protection efforts over the prior year. PPL shall summarize the latest interactions with state and federal fish management agencies concerning this report and confirm via email that the agencies agree that these monitoring efforts show sufficient progress toward the goals specified in the PA DEP Water Quality Certification, Section III, entitled Fish Passage. If established FOP goals are not being achieved, PPL shall propose solutions and implement those consistent with the PA DEP Water Quality Certification. In 2018 at the completion of Tier 1 monitoring, LIHI shall evaluate overall progress on upstream fish passage and protection for compliance with the PA DEP Water Quality certification and the FERC Operating License. LIHI certification may either be suspended or terminated if the state and federal fish management agencies do not agree that sufficient, long-term progress is being made in actual fish passage. This decision would be at the sole discretion of LIHI.
  2. PPL-Holtwood maintains Minimum Stream Flow (MSF) Operating Procedures and Requirements, in accordance with the PA DEP Water Quality Certification, Section IV. PPL Holtwood shall work to establish improved information sharing and understanding of on-going monitoring results for flows, water quality, and fish passage at their facility and others along the lower Susquehanna River, as requested and to the extent possible. Temporal resolution of data shall be sufficient to resolve subdaily fluctuations (e.g., hourly or instantaneous) in each Holtwood dam release and upstream reservoir elevations. This reporting work will begin with development of a draft plan for an annual “Integrated Monitoring Report (IMR) for Flows and Fish Passage” that will focus on existing environmental monitoring activities. The purposes of this new, annual IMR will be to synthesize monitoring results for the previous year at Holtwood in a format compatible with results from other FERC licensed projects on the river, promote understanding among relevant stakeholders, and provide easy access to Holtwood’s monitoring data. The IMR may be implemented either in an annual meeting (virtual or in-person) or a paper report, or both. The IMR will include evaluation of progress made relative to flow and fish goals established for the river. If agencies believe this IMR would be redundant with other reporting requirements already in place under FERC licenses, then PPL-Holtwood may explain how the IMR purposes will be achieved by means other than a new IMR and may propose dropping this LIHI condition, as long as monitoring data is being fully shared and better understanding of fish passage issues is being promoted.A draft plan for the IMR will be circulated to LIHI and to the U.S. Fish & Wildife Service, the PA Fish & Boat Commission, and the MD Department of Natural Resources within 60 days of LIHI certification for review and comment. The draft IMR plan will summarize current reporting requirements under the amended license and explain how monitoring data will be made electronically accessible to resource agency and LIHI staff, if so requested. Within 120 days of LIHI certification, the final plan for an annual IMR will be distributed to LIHI and the agencies, including response to comments received on the draft. The IMR will then be produced annually. Holtwood will report back to LIHI annually on the results of discussions and comments on the IMR in their annual compliance report for LIHI certification.

March 20, 2014: Public comment period on application closed.

January 20, 2014: PPL Holtwood, LLC submitted an application for certification of the Holtwood Project; comment period opened.


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