East Branch Dam Safety Initiative

Aerial view of East Branch Dam

 

 

 

 

 

Project Manager: Terry Durbin

> PROJECT DESCRIPTION

East Branch Dam is one of 16 flood control reservoirs within the Pittsburgh District that provides for flood risk reduction within the Upper Ohio River basin.  Flood control, water quality control, fish/wildlife, and recreation are all operating and authorized purposes at East Branch Dam; however, storage is only allocated for flood control and water quality control.  When not operating for flood control, East Branch Dam maintains a required temperature-flow schedule downstream on the Clarion River.   

East Branch Dam is located on the Clarion River approximately six miles northeast of Johnsonburg, Pennsylvania, and is the only project along the Clarion River main stem reservoir system. The reservoir created by the dam, East Branch Clarion River Lake, has a surface area of 1,160 acres under normal operating conditions. The drainage area of the Clarion River basin above East Branch Dam is approximately 72 square miles. 

> PROJECT STATUS  99 % Complete

 - Completed dam safety investigation into seepage-related concerns (2008)

 - Implemented interim risk reduction measures (2008)

 - Completed Dam Safety Modification Study - Assessed multiple permanent repair strategies (2010)

 - Completed design of full depth and length cutoff wall

 - Awarded $132.5 million Cutoff Wall contract (2014)

 - Accepted Cutoff Wall construction (2020)

 - Removed interim risk reduction measures (2020)

 - Return to normal reservoir and campground operating conditions (2021)

> PROJECT AUTHORIZATIONS

 - Flood Control Act of 1938 (P.L. 75-761)

 - The estimated total project cost is $280 million

> PROJECT MISSIONS

 - Flood Control        - Fish/Wildlife

 - Recreation             - Water Quality

> PROJECT BENEFITS

 - Public benefits for flood control, recreation and other purposes total $56.9 million annually

 

Documents for Public Review

Documents

Finding of No Significant Impact (FONSI) - Repair Plan
Environmental Assessment - Repair Plan

Finding of No Significant Impact (FONSI) - Interim Risk Reduction Measures
Environmental Assessment - Interim Pool
Appendix A: PA Fish & Boat Commission Study
Appendix B: PADEP NPDES Model Study
Appendix C: ERDC Temperature Model
Appendix D: Socio Economic Recreation
Appendix E: Correspondence

Summary of Public Comments

East Branch Dam Safety Initiative

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DATE OF QUESTION   QUESTION RESPONSE 
04/20/2020

Has the repair project on the East Branch Dam in Elk County, Pennsylvania been completed?

No, the repair project is not complete, however, a major project milestone was reached in March 2020 with the completion and acceptance of a concrete cutoff wall over 2,000 feet long and up to 250 feet deep.  Currently, efforts to remove the concrete work platform, replace the stone protection on the upstream face of the dam, and post construction evaluations of the repair are underway.  It is our expectation that East Branch Lake may return to normal operating conditions by the summer of 2021, weather dependent.  Our number one priority remains our commitment to public safety.

02/20/2020

I have recently heard that the fish population in East Branch Lake has taken a major hit. Is there any plans to re-introduce species to the lake when it is back at adequate levels?

The East Branch Lake fishery is strong. The Pennsylvania Fish and Boat Commission has undertaken efforts to establish the relative health of, and enhance, fisheries within the lake during the construction project. These efforts included gill-net surveys conducted in 2016 that demonstrated high and diverse productivity across various speciation and annual stocking events for multiple species. The result is that the in-lake fishery has demonstrated excellent variability and quality, and should continue to provide for a high-quality recreational fishing experience going forward.

02/11/2020 I heard a rumor there was a problem with the construction of the cutoff wall.  Is there a problem, and if so, how will it affect the raising of the lake back to normal levels?  Is the project safe? During normal quality-control procedures, the Corps discovered two areas of the cutoff wall that did not meet contract requirements.  There are no associated safety concerns; however, the contractor is required to remediate these areas and is in the process of doing so.  We are hosting a public meeting on the evening of Monday, March 2, 2020, at the Johnsonburg High School and plan to share information about when we expect to allow the lake to return to the normal operating conditions (normal pool elevations). 
 05/01/2017 We hear that the contract has been extended, is this true?  The Army Corps has extended the grouting program currently underway to ensure proper treatment of the foundation rock in preparation for installation of a full-depth seepage cutoff wall. The wall will consist of a minimum 18-inch-wide continuous vertical concrete cutoff wall approximately 2,300 feet long with an approximate maximum depth of 250 feet through the existing embankment dam into bedrock. Completion of the cutoff wall and follow on verification of the repair will allow the Corps to operate the dam at full capacity and restore the reservoir to its regular water levels. The additional work is expected to extend the dam safety project for an additional 7 months. The most recent estimated completion date of the seepage cutoff wall construction is early 2020. The Army Corps and the contractor are working to identify and implement efficiencies in sequencing of the work that will reduce the construction schedule.
 05/01/2017 Is it true that the contractor is demobilizing?  Project subcontractors demobilize as they complete their individual contract fulfillment. However the primary contractor is not demobilizing and continues to manage the project. 
  Recently, we have had many questions from concerned citizens about the historically low lake levels at East Branch Clarion River Lake. Our water management section provides the following information in response. You may also Like our Facebook site and view a video update from our Water Management Section.  

Currently, East Branch Dam Lake pool has been low. This year, the lake reached its highest pool on May 30, and since then there has been only seven days that the inflow has been greater or equal to the outflow. Every other day, the district has had to draw from the lake storage to meet its downstream flow requirement at Johnsonburg. When comparing East Branch to other lakes in the area, the Allegheny Reservoir is also low, however, it will likely reach winter pool several weeks ahead of schedule due to a lack of inflow needed to meet its downstream flow schedule. Tionesta Lake is not low because it does not have a downstream flow requirement. Other smaller non-Corps lakes in the area may still have their pool levels if recreation is their primary mission and do not have downstream flow targets to maintain.

   QUESTION RESPONSE 
  The contractor is drilling holes into the existing dam and filling them with grout. There is an area of seepage near the base of the dam where a "bus sized void" is present. I would like to know when core drilling into this void / seepage area is scheduled to take place.  I believe you're referring to the void that was detected in 1957 after muddy flows were observed downstream of the dam. Engineers at the time investigated the situation as it could have been an indication of internal erosion and a serious condition that could lead to dam failure if unaddressed. A 'bus-sized void" was detected at the time and an aggressive grouting effort was undertaken to fill the void and address any other areas in question.  

Based upon on a risk assessment in 2009, USACE determined this dam to be a high risk dam primarily due to the risks associated with re-initiation of internal erosion at or near an embankment void grouted during a 1957 internal erosion event. It was determined that the unknown condition of that repair and the potential for similar seepage events required the implementation of a dam safety initiative that in part required additional grouting and the installation of a cutoff wall through the earthen dam. Since early this year, the government's contractor has been drilling and grouting the rock underneath the dam to fill any voids and fissures in the rock prior to installation of the cutoff wall. The grouting work is ongoing at this time, including critical areas such as the previously repaired site. 

If you want to learn more about the East Branch Dam Safety Initiative, please visit http://www.lrp.usace.army.mil/Missions/Planning-Programs-Project-Management/Key-Projects/East-Branch-Dam-Repair/ and/or feel free to contact our office at any time if you have additional questions.
  QUESTION   
  I just heard today that work has been suspended on this project. I would like to know if this is true and, if so, why?  No, work has not been suspended. 
  QUESTION   
  I'm hearing that construction contract is shutting down.  Is there any truth to that?   Bencor our construction contractor is not shutting down.  Drilling and grouting work continues this summer across the dam in the embankment and foundation.  Once the grouting is satisfactorily completed the contractor is required to complete demonstration sections of the cutoff wall.   Once the cutoff wall demonstrations are satisfactorily completed then the remainder of the cutoff wall can be completed. 
  QUESTION RESPONSE
  Any truth to the QUESTION that the repair would take several years to finish?

 

Yes, the proposed repair will take several years to design and build; if all goes as currently planned, especially receiving appropriate funding, we project a completion date of 2018. This is an optimal estimate, potentially impacted by many variables including: funding, selected repair plan, weather.

 

  QUESTION RESPONSE
  Would it require the draining of the lake?

 

No. Constructing the cut-off wall is not expected to reqire draining the lake.

  QUESTION RESPONSE
  When will we know the status of the lake?

 

The next public meeting is scheduled for April 11, 2013 at 7 p.m. at Johnsonburg High School. An updated dam safety status report will be added to the East Branch home page and dam safety page.

 

  QUESTION RESPONSE
  Does it need repair and if so, when will the repairs take place?

 

The repair of the dam was approved in Oct. 2010. An internal cut-off wall has been approved to repair the dam. Construction could start as early as fall 2013. 

  QUESTION RESPONSE
  I have heard that the dam needs to be drained for safety issues, but you are not doing so because of pressure from the Domtar Mill.

 

The decision to lower the reservoir, and to what level was based solely on public safety. Dam safety professionals within the Corps of Engineers determined that implementation of specific risk reduction measures, including our current pool restriction, would allow safe operation of the dam while investigations are undertaken at the site. We are working closely with the Domtar Mill, DCNR, PA Fish & Boat Commission and other stakeholders to ensure we reduce the impacts of this necessary dam safety investigation; however, life safety is our number one priority and will be paramount in directing our current and future actions.

 

  QUESTION RESPONSE
 

Is kayaking permitted on East Branch Lake?

Yes, kayaking is allowed on the lake. Also, both the federal and the state Instanter boat launches are open for hand- and trailer-carried boats. The launch fees for have been waived.

 

 

  QUESTION RESPONSE
 

How much water is there?

The amount of water in East Branch Lake varies through the year. The amount of water in a lake or reservoir is usually measured in acre-feet. One acre-foot is enough water to cover an acre of land one foot deep. At the historic normal summer pool, elevation 1670, East Branch Lake contained 64,000 acre-feet of water. As currently operated the lake contains 44,000 acre-feet of water at the interim summer pool, elevation 1650. The amount of water will drop to about 15,000 acre-feet by late fall. (For perspective, one acre-foot of water is equivalent to 325,900 gallons.)

For water level equivalents, visit: http://www.irwd.com/MediaInfo/water_equivalents.php

 

  QUESTION RESPONSE
  If the dam were to break, how long would it take for Wilcox, Johnsonburg and Ridgway to be flooded.  Even though you say it won't break, how long do you estimate that we, living in Ridgway would have before it hit us?

To be most cautious in emergency planning, we base our calculations on the worst case scenario of the lake being completely filled and a rapidly occurring breach in the dam. In reality, conditions are very unlikely to be so extreme. In over fifty years of operation, the East Branch Lake has yet to be filled to capacity. Even during the record Hurricane Agnes event in 1972 the lake level was over 12 feet below maximum pool and twenty-one feet below the top of the dam. In addition, the dam is inspected and monitored closely for advance indications of developing problems. During a serious seepage-related incident in 1957, observation of unusual seepage conditions allowed ample time to take action to prevent a failure.

Based on our emergency action plan reflecting the worst case scenario, Johnsonburg, seven miles downstream of the dam, would see the first flood water arrive two hours after a breach. The peak flood would occur 30 minutes later. At Ridgway, 15 miles downstream of the dam, the first flood water would arrive three hours after a breach, and the peak flood would occur in three hours and 30 minutes. The town of Wilcox is not in the path of flooding because it is located well upstream in the valley of the West Branch, a different fork of the Clarion River.

 

  QUESTION RESPONSE
 

Is the lake closed?

No. The lake is not currently closed; however, in the interest of public safety, the campground and picnic area will be closed starting in 2014 through completion of construction. 

  QUESTION RESPONSE
 

Is East Branch Dam about to fail?

Public safety is the number one priority of the Corps' Dam Safety Program. Our screening process at East Branch Dam identified confirmed seepage-related issues. To reduce the risk to the public, Pittsburgh District implemented several interim risk reduction measures, including increased monitoring; 24/7 staffing; updated emergency action plans; and reduced water levels in the reservoir to relieve pressure on the dam. These and other short-term actions allow us to operate the dam to meet our public safety objective while we further investigate our concerns and pursue long-term repairs, if necessary.

  QUESTION RESPONSE
 

Is the Corps planning on draining the lake?

The Corps reviews it decision on operating the reservoir pool at least annually. The Corps will continue to operate the reservoir pool level consistent with the approved interim water control plan unless the condition of the dam changes. No further changes in reservoir operations are anticipated at this time.

  QUESTION RESPONSE
 

If the dam is unsafe, why isn't the Corps draining the lake?

The Corps has implemented risk reduction measures to ensure we are operating the dam to our safety standards. Public safety is our number one priority. Our preliminary investigations support our decision to operate the reservoir under the current interim water control plan.

History of East Branch Dam Safety Initiative

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History of East Branch Dam Safety Initiative (2006)

East Branch Dam is owned and operated by the Pittsburgh District, U.S. Army Corps of Engineers.  As part of a risk management approach to improving public safety, the Corps has classified East Branch Dam as Dam Safety Action Class (DSAC) II.  East Branch Dam is considered to have unconfirmed (potentially unsafe) issues which merit further study and analysis, largely because it has a history of seepage related problems, including a serious episode in 1957 that required lowering the lake until repairs could be made.  There have been no observed changes in seepage conditions or performance of the dam in the time since repairs were completed.  The dam functioned safely during the record pool event in 1972 resulting from Hurricane Agnes.  As a result of the DSAC II classification, the Pittsburgh District has implemented Interim Risk Reduction Measures to reduce the risk to the public.  These measures include increased monitoring, 24/7 staffing, updating emergency operation plans, reducing the water level in the reservoir to relieve pressure on the dam and stockpiling emergency materials on site.

These and other short-term actions allow us to operate the dam to meet our public safety objective while we further investigate our concerns and pursue long-term repairs, if necessary.  As we take steps to reduce risk to public safety, we recognize that recreation, water supply, hydropower and the environment may be impacted.  The Pittsburgh District staff will continue to work with our stakeholders and the public to keep them informed of the dam safety issues related to East Branch Dam.

The U.S. Army Corps of Engineers’ Dam Safety Program is critical to addressing our nation’s aging infrastructure, reducing the risks of flood and storm damage and making sure Corps owned and operated dams are operated safely and minimize risk to the public.

The Corps owns and operates 610 dams that serve a variety of purposes including navigation, flood damage reduction, water supply, irrigation, hydropower, recreation, environmental enhancement and combinations of these purposes.  The Pittsburgh District owns and operates 16 flood damage reduction dams and 23 navigation locks and dams.  As part of our responsibility in managing these dams, the Corps has a comprehensive Dam Safety Program that has public safety as its primary objective. Corps dams are routinely inspected and continually evaluated for safety in accordance with the Federal Guidelines for Dam Safety issued in 1979.

Risk management changes are being implemented in the Dam Safety Program to allow prioritization of work at the national level, thereby providing a standard strategy for the continued safety and security of our projects and the affected public.  Dam safety risk has two components:  probability of dam failure and consequences if failure were to occur.

In 2005, 2006 and 2007 the Corps of Engineers performed Screening Portfolio Risk Analysis that considered performance and consequence of failure (risk-informed screening) to prioritize approximately one-third of Corps-owned and operated dams nationwide that were perceived to have the highest risk.  All 16 Pittsburgh District flood damage reduction dams and four of our 23 navigation dams were screened as of 2007.  The Corps of Engineers goal is to screen the remainder of the portfolio by the end of Fiscal Year 2009.

The Corps of Engineers instituted a Dam Safety Action Classification System intended to provide consistent and systematic guidelines for appropriate actions to address the dam safety issues and deficiencies.  Corps dams are placed into five Dam Safety Action Classes (DSAC) based on their individual dam safety risk considered as probability of failure and potential failure consequences.  DSAC I is the rating assigned for the highest risk dams, and DSAC V are dams which are considered safe and in compliance with current criteria.  Consequences considered include lives lost, economic, environmental and other impacts.

The Corps of Engineers has identified six DSAC I flood damage reduction projects based on the risk analysis screenings to date.  None of Pittsburgh District’s flood damage reduction dams were identified as DSAC I, and one flood damage reduction dam, East Branch Dam, was identified as DSAC II.

East Branch Dam is located on the East Branch Clarion River in Elk County, Pennsylvania.  Construction began in June 1948 and was completed in October 1952.  Impoundment of water began in November 1950 with full operation in June 1952.  Normal summer pool is elevation 1670.  The pool of record is elevation 1685.6, reached on June 24, 1972 as a result of Hurricane Agnes.  This pool level was .6 feet above the spillway crest elevation and was the only time the spillway carried flow.  The dam functioned safely during this event.

The dam is a rolled earth fill embankment with outlet works located at the right abutment and an emergency spillway located in the left abutment.  The embankment is 1,725 feet long and has a height of 184 feet.  The width is 20 feet at the top of the dam with a maximum width of 1,115 feet at the base.  The project purposes are reduction of flood stages on the Clarion River, water conservation, water quality, supplementary low-flow, recreation and conservation of fish and wildlife.

The dam experienced a serious seepage related incident in 1957.  In May, muddy water appeared at the toe of the dam near the right abutment.  The pool was drawn down a total of 110 feet in three stages and exploratory drilling was conducted.  The exploratory drilling revealed internal erosion that created a cavity in the impervious core of the embankment.  Repairs consisting of drilling and grouting sealed the cavity and surrounding area.  Grouting was completed in November 1957.  There have been no observed changes in seepage conditions or performance of the dam in the time since repairs were completed; however, the repair is now more than 50 years old.

East Branch Dam is inspected and monitored closely.  The dam is instrumented to monitor seepage, piezometric levels (internal seepage pressure) and horizontal and vertical movements of the dam crest.  The dam is staffed seven days a week, 24-hours a day and is regularly inspected by project staff as well as engineers from the Pittsburgh District Office.  Project staff inspects the dam daily during normal operating conditions and more frequently during high pool levels.  Engineers inspect the dam at least annually, with more intensive team inspections every five years through the Dam Safety Program.

East Branch Dam was screened in 2006 as part of the Screening Portfolio Risk Analysis process.  As a result of the screening assessment, the dam was classified as DSAC II.  East Branch Dam is considered to have unconfirmed (potentially unsafe) issues which merit further study and analysis.

East Branch Dam has been given priority funding to implement Interim Risk Reduction Measures and study alternatives for long-term remedial measures, if needed.  The steps following initial classification and leading to approval of long-term remediation are considered a Dam Safety Study.

Step 1.  The first step in the East Branch Dam Safety Study was to prepare an Interim Risk Reduction Measures Plan and implement the proposed measures.  Interim risk reduction measures are not long-term solutions, they are designed to minimize risk to public safety in the short-term while pursuing long-term permanent fixes. They are an important step to minimize the probability of failure and/or consequence until a permanent fix can be implemented or investigations have determined that a potential failure mode is not probable.  It is the most responsible way to manage a project’s risk to public safety.  As we take action to reduce risk to public safety, which is our first priority, we recognize that other project benefits, such as recreation, water supply and water quality may be impacted.

The Pittsburgh District has implemented, or will implement, the following Interim Risk Reduction Measures for East Branch Dam:

  • Operate at a reduced operating pool level
  • Update the existing dam safety emergency action plan
  • Conduct emergency exercises
  • Provide 24/7 staffing
  • Update inundation mapping
  • Enhance inspection and monitoring
  • Pre-position contracts and stockpile materials
  • Improve reliability of the outlet gates and machinery
  • Perform a more detailed risk assessment

A key interim risk reduction measure is to operate East Branch Dam at a reduced pool level.  This action will both reduce the probability of failure due to internal erosion and reduce potential consequences if a failure were to occur.

Step 2.  Preliminary Dam Safety Studies are the next step in evaluation of dam safety issues.  These studies include a more in-depth review of available data and a more detailed risk analysis of all potential failure modes in order to better define and confirm the dam safety issues.  The Dam Safety Action Classification will be reviewed and modified as appropriate.  The Interim Risk Reduction Measures will be reviewed and modified based on the detailed risk analysis.

Step 3.  Dam Safety Modification Studies will follow if justified by the confirmed dam safety issues.  Modification studies include additional data gathering, studies and detailed engineering analyses.  A full range of alternatives are evaluated with detailed cost estimates as well as assessments of other impacts.  Modification studies will lead to a decision document with a comparison of alternatives and a recommended plan.

Public safety is the number one priority of the U.S. Army Corps of Engineers.  The primary objective of our Dam Safety Program is to maintain public safety by making sure the dams we own and operate are safe and risks to the public are minimized.

An integral part of the Corps of Engineers Dam Safety Program is its risk-informed screening process, Screening Portfolio Risk Analysis. The Corps is focusing on projects with the most compelling dam safety issues first, as identified by this risk-informed screening process.

Screening Portfolio Risk Analysis screened dams are classified based upon confirmed or unconfirmed dam safety issues, the combination of life or economic consequences should failure occur and the probability of failure.  This enables the Corps to prioritize dam safety actions to correct deficiencies, which includes interim risk reduction measures to be undertaken while further investigations are conducted and/or remedial actions are implemented.

East Branch Dam has a history of seepage related problems, including a serious episode in 1957 that required draining the lake until repairs could be made.  There have been no observed changes in seepage conditions or performance of the dam in the time since repairs were completed.  The dam functioned safely during the record pool event in 1972.

Our screening and classification of East Branch Dam identified this project as having unconfirmed (potentially unsafe) issues which merit further analysis and evaluation.  We are taking a number of interim risk reduction measures in order to reduce the probability and consequences of dam failure while long term remedial measures are pursued.  As a key interim risk reduction measure the dam will be operated at a reduced pool level.

Interim risk reduction measures are not long term solutions.  They are designed to buy down or minimize risk to public safety in the short-term while pursuing long-term permanent modifications to a dam.  They are an important step to minimize the probability of failure and/or consequence until a permanent fix can be implemented or investigations have determined that a potential failure mode is not probable.

East Branch Dam has received priority for further studies to better define and confirm the dam safety issues. Through this process, the Corps will determine whether or not the dam is in need of repairs and evaluate alternatives for permanent repair.  The process of evaluation is expected to take about two years.  We will continue to work with our stakeholders to keep them informed of the dam safety issues related to East Branch Dam.

The Pittsburgh District operates and maintains East Branch Dam in such a way as to minimize risk to the public. East Branch Dam is inspected and monitored closely.  The dam is staffed seven days a week, 24 hours per day and is regularly inspected by project staff as well as engineers from the Pittsburgh District Office.