The Plight of Aging Dams, and One Solution

As dams age, the danger to life and property around them increases. If they were to suddenly fail and flood downstream communities and infrastructure, there would be serious loss of property and life. More and more, dam removal has become the best option for property owners who no longer want or can no longer afford the rising cost of maintenance and repair work required to maintain such a complex structure.

The Courier-Post recently published this Commentary piece titled, “The Plight of Aging Dams, and One Solution”, which was written by Princeton Hydro’s Vice President and Principal Engineer Geoffrey M. Goll:

Many of our nation’s dams, while originally intended to provide benefits for mills, water supply and energy generation, are severely aged and unmaintained. Nearly 20,000 of the dams on the Army Corps of Engineers’ National Inventory of Dams – which doesn’t even include many dams that are not inventoried or known about – were built in the 1960s. With expected lifespans of 50 years, these dams have reached their limit. And by 2020, 70 percent of all dams will be over 50 years old. Like roads and bridges, dams also require upkeep, maintenance and eventually removal or rehabilitation.

As dams age, the danger to life and property around them increases. If they were to suddenly fail and flood downstream communities and infrastructure, there would be loss of property and life. The Association of State Dam Safety Officials, the professional organization for dam safety engineering professionals and regulators, estimates there would need to be a $21 billion investment to repair just 2,000 deficient, high-hazard dams. More and more, the removal of dams has become an option for owners who no longer want or no longer can afford the rising cost of maintenance and repair work required to maintain such a complex structure.

For dams like this, removal benefits local economies, and eliminates threats to people and property in local communities. There are also many byproduct benefits, including restoring fish migration routes, improving water quality, restoring floodplain functions and values, and increasing biodiversity.

On Sept. 8, we had the honor of meeting the Secretary of the Interior Sally Jewell during a visit of our Hughesville Dam removal project on the Musconetcong River, located in northwestern New Jersey. This project exemplifies the successes that can be achieved through public-private partnerships, including local communities, state and federal agencies, nongovernmental organizations, and private commercial entities. This is the fifth dam removed on the Musconetcong River by a coalition of stakeholders, led by the Musconetcong Watershed Association. The Department of the Interior (specifically, the U.S. Fish and Wildlife Service) provided funding to remove this very old, out-of-compliance dam.

The success of these partnerships is due to the unique strengths that each organization brings to the table. This project achieved the removal of a flood and safety hazard, and will restore additional river miles for migratory fish, improve water quality by removing the heat sink of the reservoir, and provide additional safe passage for recreation along the river.

It is easy to see why Secretary Jewell chose this site to visit, but the old and outdated dam at Hughesville is far from alone. Across the nation, we need to remove dams like this at a much larger scale – aging dams that no longer are of value to us, but increase the danger to those who live downstream. If we can build on this momentum and start to address the issue of dam safety compliance on a national scale, we can address these threats to American’s safety and strengthen local economies.

The Westtown Dam and Lake Restoration Project is Now Complete!

westtown-0720161456Princeton Hydro is proud to announce the completion of the Westtown dam restoration and dredging project. For the past 10 years, Princeton Hydro has been working with the Westtown School on dam safety compliance and lake restoration and is the engineer-of-record for the restoration of the Westtown dam and lake.

Westtown School, a hallmark of the Westtown Lake community, initially contracted Princeton Hydro to complete dam inspections and assess the lake in terms of its environmental health and the need for dredging. The completion of this project is a testament to the School’s commitment to its mission of “inspiring and preparing its graduates to be stewards and leaders of a better world”. The School leads by example through practicing dam safety compliance and working to restore the lake for future generations.

westtown-img_2438For the dam, Princeton Hydro completed periodic visual inspections, dam breach and inundation analysis, the preparation of an Emergency Action Plan (EAP), and the Operations and Maintenance Manual.

For rehabilitation, Princeton Hydro designed the dam to be able to pass the 100-year flood event via a completely new drop spillway and outfall barrel, and the construction of an auxiliary/emergency cast-in-place stepped spillway. As part of the rehabilitation of the dam, Princeton Hydro surveyed and designed the dredging of 56,000 cubic yards of sediment, the rehabilitation of the lake’s sedimentation forebay and spillway, and the enlargement of a culvert on Westtown Road, immediately downstream of the dam. The culvert replacement was required due to the closure of two secondary outlets on the dam and corresponding culverts below Westtown Road.

westtown-0713161041aThis project also required a variety of permits, including a Chester County soil erosion and sediment control plan approval, a Dam Safety construction permit, a PADEP General Permit 11 for the road crossing, and a US Army Corps of Engineers Individual Permit in compliance with the Federal Clean Water Act.

Additionally, Princeton Hydro successfully navigated interests for two species of concern: the bog turtle (federal and state listed) habitat and red-bellied turtle (state listed) populations.

Following design and permitting, Princeton Hydro provided construction documentation and administration, including the review of shop drawings, monitoring soil compaction, inspecting concrete pours and collecting concrete test cylinders for break tests (ACI certified engineers), completing monthly progress reports, reviewing payment requests and change orders, and attend bi-weekly project meetings with the client. Flyway Excavating, the contractor for the project, worked seamlessly with the School and Princeton Hydro to accomplish the overall goals of the design.

The Westtown project is an excellent example of Princeton Hydro’s turnkey engineering, permitting, and construction administration services. Please contact us if you have a similar project you need assistance with or have questions about.

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*Photos courtesy of Flyway Excavating.