Goose Pasture Tarn Dam Project

The Goose Pasture Tarn Dam is owned and operated by the Town of Breckenridge.  The water within the Tarn is owned by the Town of Breckenridge.  The land around the Tarn is privately owned.  The Town of Blue River residents have recreational rights to use the Tarn.

In spring of 2021, the Town of Breckenridge will begin the process of replacing the existing dam.  The Town of Blue River is working with the Town of Breckenridge to ensure residents are informed of all work being conducted and to address questions and concerns.  For complete information on the Tarn Dam project please visit the link below.

https://www.townofbreckenridgegptd.com/timelines-construction

 

 

Goose Pasture Tarn Dam Rehabilitation

Project Update – 4/7/2022

Two-Week Construction Look-Ahead (April 7-April 21, 2022):

  • The Contractor is continuing to construct drilling access for Sonic drill to install de-watering wells around the stilling basing. 
  •  The Contractor will continue to bypass reservoir inflows into the 96-inch bypass pipeline.  The reservoir Elevation will slowly increase from 9865 to 9875, when the inflows will pass through the 96-inch bypass pipeline without a bypass pump.  
  • The Contractor will continue forming, installing rebar, and pouring concrete into an excavation at the crest of the dam for the crest cutoff wall.
  • The dewatering well subcontractor will continue to install the dewatering system for the stilling basing construction.
  • The temporary shoring wall subcontractor will mobilize to the site to continue shoring wall construction along the left side of the existing RCC emergency spillway and stilling basin.

Reservoir Levels and Groundwater Level Monitoring

  • The Town of Breckenridge has installed 6 temporary monitoring wells around the reservoir within 350 feet of the reservoir edge to monitor changes in groundwater levels before, during, and after the drawdown periods. Groundwater levels in some wells has fluctuated in response reservoir drawdown and refilling.  A plot showing groundwater elevations in these wells and the reservoir surface elevation, and a map showing the well locations can both be found in the “Reservoir and Groundwater Levels” section of this website. Information about projected impacts to residential water wells can be found in the “Private Well Info” section of this website. Currently no readings are being taken due to ice/snow covering the well access points.
  • The Town and Contractor have dropped the water level in the Tarn to allow for the current phase of the rehabilitation.

Reservoir Neighbor Outreach and Assistance

  • The Town has identified those neighbors with the greatest possibility of experiencing a disruption of well water supply during the drawdown based on their proximity to the reservoir and the depth of their wells. Letters, flyers, emails, and phone calls went out to those neighbors last season to acquaint them with the measures the Town has prepared to assist them with their water supply if necessary.
  • The construction dewatering wells may impact local groundwater levels around the dam.  Neighbors who may be affected have already been contacted by the Town.
  • There is a smaller possibility that additional properties located within 350 feet of the reservoir may experience a disruption in their well water supply during the drawdown period. If you experience a disruption in your well water supply, please contact the Town at 970-453-3170 or breckenridgegptd@townofbreckenridge.com.

 

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For Immediate Release:                                                                                                                             

April 1, 2021

 

 

Contact:      

James Phelps, Public Works Director, jamesp@townofbreckenridge.com

Haley Littleton, Communications, haleyl@townofbreckenridge.com

 

Town of Breckenridge begins Rehabilitation Construction on Goose Pasture Tarn Dam

The Town of Breckenridge is beginning a three-year project that is focused on rehabilitating the Goose Pasture Tarn Dam (GPTD) in Blue River.  The rehabilitation, which primarily includes replacement of two existing spillways with a single larger spillway, is intended to improve the safety and long-term operation of the dam. This project is planned for joint funding by FEMA, the State of Colorado, and the Town of Breckenridge. Moltz Constructors, Inc was recently selected as the general contractor for the project. Construction is planned to start in April 2021 and be completed by the fall of 2023.

The Goose Pasture Tarn Dam is a 57-foot high zoned earthen dam located on the Blue River, 2 miles south of Breckenridge. It was constructed in 1965 and has been owned and operated by the Town of Breckenridge since 1970. An emergency spillway was constructed in 1990 to provide additional spillway capacity above that provided by the concrete service spillway included as part of the original dam. This dam provides water to the Gary Roberts Water Treatment Plant serving residents of Breckenridge.

It is one of 429 Colorado dams classified as “High Hazard” based on estimated consequences if the dam were to fail and is not on the condition of the dam (2018 National Inventory of Dams, US Army Corps of Engineers). In 2016, safety issues with the use of the concrete service spillway during high flows were identified. The Town of Breckenridge took immediate steps to ensure the safety of the dam. Colorado Dam Safety imposed a reservoir storage restriction, lowering the water level that could be stored in the reservoir by 4 feet to a safer level, and restricted flows down the service spillway. The Town Public Works staff regularly monitors dam conditions through visual observation, and a series of monitoring wells (aka piezometers) and drains. Colorado Dam Safety personnel and engineers working for the Town inspect the dam on a yearly basis. The reservoir will be kept at the restricted level imposed by Colorado Dam Safety until a new spillway has been constructed. A plan to safely divert river flows around the dam during construction will be implemented. A recently updated emergency action plan for quickly addressing any unanticipated dam safety issues, was developed jointly by the Town, W. W. Wheeler & Associates, Colorado Dam Safety, and Summit County Emergency Management.

Planned Rehabilitation will include:

  • Replacement of the existing service spillway and emergency spillway with a single overtopping concrete spillway.

  • A 2.6foot increase in the height of the dam crest for flood protection only (the increase will not result in additional reservoir storage capacity).

  • Construction of a new drainage system designed to safety control seepage through the dam.

  • Lining of the 54-year old outlet conduit to protect against outlet leaks that could impact dam safety.

“This is an incredibly important project for public safety in Breckenridge, and we’re eager to get to work on it,” comments James Phelps, Public Works Director, “Public safety is our number one goal, and we’re glad that, despite the pandemic, we’ve been able to resume the planned rehabilitation of this key piece of water infrastructure. We’re also pleased to have assistance from FEMA for this large scale project.”

The estimated construction cost, excluding engineering and permitting, is approximately $20 Million. The Town has been selected by FEMA for funding ($10 million) under the Pre-Disaster Mitigation Grant program for the rehabilitation project, contingent on satisfying FEMA requirements.

​The GPTD reservoir water level will be lowered for both this year and next year’s construction seasons.  The reservoir lowering may have an impact on the residential wells in close  proximity to the reservoir. The Town has installed monitoring wells as one measure to evaluate potential impacts by tracking fluctuations in groundwater levels adjacent to the reservoir.  The Town will continue to perform assessments and will enact additional measures to reduce those impacts whenever possible. The Town has also contacted residents around the reservoir and is working with the Town of Blue River to manage and mitigate impacts. Recreational use of the reservoir is prohibited during the project.

Residents and homeowners can find updated construction timelines, notices, and information at the project website, www.townofbreckenridgegptd.com. For a thorough overview of the dam project, resources can be found here: FAQ for surrounding residents and FAQ for general public. If the public has any questions regarding the project and any potential impacts like traffic, construction, and water, please email breckenridgegptd@townofbreckenridge.com. Residents who would like to sign up for a monthly newsletter regarding the construction can email this address to be subscribed.

 

 

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Tarn Dam Project April 2022

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