Restoring Ballinger Lake Dam in Medford Lakes, NJ

Medford Lakes is a borough in Burlington County, New Jersey that consists of 22 lakes, and more than 10% of the homes there are log cabins. Located just 25 miles east of Philadelphia, within the New Jersey Pinelands Commission Management Area, the Borough is overseen by the Medford Lakes Colony (MLC), a homeowners association that manages social events and recreation activities for the community and also manages its “Lake Restoration Fund.” All homeowners in the community contribute to the Fund, which is used to manage and monitor lake water quality and maintain water control structures like dams and culverts.

Medford Lakes and its surrounding neighborhoods contain approximately 60 dams. The MLC retained Princeton Hydro to provide various engineering services for multiple dam structures throughout the Borough, including periodic visual inspections, dam breach and inundation analysis, and maintenance and repair work.

Ballinger Lake, located at the intersection of Lenape Trail and Stokes Road, contains a dam that is registered as a Class I – High Hazard Dam with NJDEP Division of Dam Safety. Immediately downstream from the dam is Main Street Medford Lakes, a congested portion of the Medford Lakes Borough.

The dam, originally constructed in the 1920s, is an earthen embankment dam with a clay core. Between 2000 – 2001, a reconstruction project took place that included the creation of both a primary and auxiliary spillway and a concrete culvert. The primary spillway consists of a concrete drop box and culvert that passes through the embankment. The auxiliary spillway, armored with articulated concrete block, is a low point on the embankment along Stokes Road.

In 2008, the Ballinger Lake Dam was inspected by Princeton Hydro and the NJDEP, Division of Dam Safety. The results of these inspections revealed considerable seepage at one of the concrete joints within the concrete culvert, a non-compliant trash rack assembly, a distressed gate valve assembly, and unstable downstream conditions.

Under Princeton Hydro’s direction, the lake was lowered to reduce the hydraulic load on the dam and to facilitate the required remediation and repairs. Princeton Hydro provided full turn-key engineering services that encompassed the development of the engineering documents and plans and preparation of all the permitting requirements (NJDEP Dam Safety, Pinelands Commission Certificate of Filing (CoF), NJDEP Dam Safety Emergency Permit, Burlington County Soil Conservation Erosion and Sediment Control, and NPDES permits). Our team also prepared the contractor bid specifications and provided construction oversight and management throughout the course of the repairs.

Throughout this process, Princeton Hydro completed multiple studies to characterize the hydraulic, hydrologic, structural, stability, geotechnical, and groundwater conditions at the dam under pre and post-repair conditions. The team eliminated the leakage and brought the dam back into compliance.  In 2019, MLC contracted Princeton Hydro to perform additional maintenance and improvements to the Ballinger Lake Dam spillway, outfall, and sluice gate.

The scope of work for the 2019 engineering and construction project included the following:

  • Replacement of the failed sluice gate structure
  • Installation of a baffled culvert extension on the downstream side of the existing culvert
  • Regrading of the downstream embankment to a shallower, uniform 3H:1V slope
  • Regrading of the levee crest to a uniform elevation
  • Riprap armament of the downstream channel
  • Various repairs to joints and spalls within the existing concrete dropbox and culvert structures.

The photo above, taken on September 23, 2019 by Princeton Hydro, shows a view of the lowered lake level and pumping intake hose.

Construction began on September 19, 2019 with the lowering of Ballinger Lake to facilitate the work within the existing dropbox structure. The lake lowering process was performed by a 6-inch centrifugal pump, which discharged water into the downstream channel. The photo above, taken on September 23, 2019, shows a view of the lowered lake level and pumping intake hose. After the lake was lowered below the dropbox crest, all of the concrete was power washed and work began to waterproof and repair all of the joints within the culvert.

The above photo, taken on October 17, 2019 by Princeton Hydro, shows the riprap being removed from the stream bed prior to pouring the flowable fill concrete mud mat.

In October, the team began removing portions of the existing stream bed riprap in preparation for pouring a flowable fill-based mud mat to level the foundation of the culvert extension. The area was dewatered with a submersible pump, with the discharge filtered through a sediment bag and directed back into the downstream channel at a point upstream of the installed turbidity barrier. The above photo, taken on October 17, 2019, shows the riprap being removed from the streambed prior to pouring the flowable fill concrete mud mat.

The above photo taken by Princeton Hydro shows the grate being prepared for the installation of the sluice gate valve operating mechanism.

The installation of the sluice gate valve support structure began in November 2019. Princeton Hydro oversaw the process to ensure the installation was being completed according to the design drawings and NJDEP Dam Safety regulations. The above photo taken by Princeton Hydro shows the grate being prepared for the installation of the sluice gate valve operating mechanism.

Photo taken on December 5, 2019 by Princeton Hydro showing the soil erosion mat being installed.

In December 2019, the team completed a topsoil application, seeding, and soil erosion matting installation to all disturbed areas of the site. All areas disturbed by construction activities (approximately 6,400 square feet) were graded to pre-construction conditions. The topsoil was applied to these areas and hand-raked to re-establish the original grades. The area was then seeded with perennial ryegrass, fertilized, and covered with a soil erosion mat. The above photo, taken on December 5, 2019, shows the soil mat being installed.

Following the final site inspection performed by Princeton Hydro in April 2020, we completed the Ballinger Lake Dam Spillway & Sluice Gate Improvements Closeout Report and presented it to MLC. The report confirmed that the site was considered stabilized in accordance with the approved project plans, the Standards for Soil Erosion and Sediment Control in New Jersey, and all NJDEP Bureau of Dam Safety requirements.

Princeton Hydro has designed, permitted, and overseen the reconstruction, repair, and removal of dozens of small and large dams in the Northeast. Click below to read about an emergency repair we completed on the Lake Wauwauskashe Dam. A concerning blockage developed in Lake Wauwauskashe Dam’s spillway and water was backing up at the upstream outlet structure causing a number of issues and potential hazards. Medford Lakes Colony, Princeton Hydro, and other project partners employed innovative solutions that lead to a successful emergency repair.

Creative, Timely Solutions Lead to Successful Dam Repair in Medford Lakes

To learn more about our dam and barrier engineering services, visit bit.ly/DamBarrier.

 

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.