Plaster Reservoir Open Space Management Plan

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The City and County of Broomfield staff are working to develop a management plan for Plaster Reservoir. The plan will include on-going maintenance recommendations, near-term capital improvement project recommendations (within next 10 years), and identification of any long term capital improvement projects.

Plaster Reservoir, a key feature of Broomfield’s open space holdings and is adjacent to the Broadlands Golf Course, is located within the Quail Creek Drainage Basin, northeast of the intersection of Lowell Boulevard and West 136th Avenue. The primary objectives for Plaster Reservoir are to provide stormwater detention, wildlife habitat, public trail corridors and aesthetic value for Broomfield residents, the adjacent neighborhood and golf course patrons.

Previous Work

In 2012 ICON Engineering, Inc. completed a reservoir dredging assessment for Plaster Reservoir to determine if dredging was required or recommended for water quality and/or flood control, and to establish a prioritized capital improvement program for reservoir dredging. This assessment determined that from a flood storage perspective, dredging was not necessary at the time. The assessment also noted that the large amount of cattails to the west of the open water was creating a near stagnant flow along Quail Creek directly upstream of the reservoir. This issue, in addition to other factors (such as fertilizer runoff from the adjacent golf course) have likely contributed to periodic odor issues.

The Current Project

The City and County of Broomfield, through a competitive RFP process, has hired SMITH Environmental and Engineering to develop a reservoir management plan for Plaster Reservoir. This management plan will provide guidance to the City on how to approach the maintenance of Plaster Reservoir in order to maintain flood attenuation capacity, enhance and support ecosystem health, preserve public trail access, maintain wildlife education experiences and manage and reduce odor issues both over the short and long term.

Beginning in September 2020, SMITH will be working with City staff over the next six months, to develop a management plan which will include on-going maintenance recommendations, near-term capital improvement project recommendations (within next 10 years), and identification of any long term capital improvement projects. The management plan will objectively prioritize management activities and make recommendations on how to implement said activities based on cost, feasibility and expected effectiveness.

The final management plan report will include clear and concise, yet detailed, rationale for all findings and recommendations, including key assumptions and any data gaps. It will include easy to understand decision making tools (e.g., flow chart, decision matrix, etc.) based on a variety of factors (i.e., anticipated level of benefit, technical feasibility, cost effectiveness, etc.).

The view from the south bank of Plaster Reservoir.

The City and County of Broomfield staff are working to develop a management plan for Plaster Reservoir. The plan will include on-going maintenance recommendations, near-term capital improvement project recommendations (within next 10 years), and identification of any long term capital improvement projects.

Plaster Reservoir, a key feature of Broomfield’s open space holdings and is adjacent to the Broadlands Golf Course, is located within the Quail Creek Drainage Basin, northeast of the intersection of Lowell Boulevard and West 136th Avenue. The primary objectives for Plaster Reservoir are to provide stormwater detention, wildlife habitat, public trail corridors and aesthetic value for Broomfield residents, the adjacent neighborhood and golf course patrons.

Previous Work

In 2012 ICON Engineering, Inc. completed a reservoir dredging assessment for Plaster Reservoir to determine if dredging was required or recommended for water quality and/or flood control, and to establish a prioritized capital improvement program for reservoir dredging. This assessment determined that from a flood storage perspective, dredging was not necessary at the time. The assessment also noted that the large amount of cattails to the west of the open water was creating a near stagnant flow along Quail Creek directly upstream of the reservoir. This issue, in addition to other factors (such as fertilizer runoff from the adjacent golf course) have likely contributed to periodic odor issues.

The Current Project

The City and County of Broomfield, through a competitive RFP process, has hired SMITH Environmental and Engineering to develop a reservoir management plan for Plaster Reservoir. This management plan will provide guidance to the City on how to approach the maintenance of Plaster Reservoir in order to maintain flood attenuation capacity, enhance and support ecosystem health, preserve public trail access, maintain wildlife education experiences and manage and reduce odor issues both over the short and long term.

Beginning in September 2020, SMITH will be working with City staff over the next six months, to develop a management plan which will include on-going maintenance recommendations, near-term capital improvement project recommendations (within next 10 years), and identification of any long term capital improvement projects. The management plan will objectively prioritize management activities and make recommendations on how to implement said activities based on cost, feasibility and expected effectiveness.

The final management plan report will include clear and concise, yet detailed, rationale for all findings and recommendations, including key assumptions and any data gaps. It will include easy to understand decision making tools (e.g., flow chart, decision matrix, etc.) based on a variety of factors (i.e., anticipated level of benefit, technical feasibility, cost effectiveness, etc.).

The view from the south bank of Plaster Reservoir.

  • Open Space and Trails Advisory Committee Meeting October 28, 2021 Responses to Questions related to the Plaster Reservoir Open Space Management Plan

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  • October 2021 - Plaster Reservoir Management Plan Update

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    In 2020, Broomfield engaged Smith Environmental and Engineering (SMITH) to develop a reservoir management plan that outlined an approach to the maintenance of Plaster Reservoir. The impetus for the project was the odor complaints that Parks and Open Space & Trails had received in the past from residents who live around the reservoir.

    The management plan consisted of three phases: Data Gathering, Public Engagement and Development of Recommendations. The Data Gathering phase consisted of field measurements of flood storage capacity, an assessment of ecosystem health through the observation of vegetation and wildlife as well as the review of water quality data, and the observation of existing passive recreation opportunities. The Public Engagement phase included a public open house, and two presentations to the Open Space and Trails Advisory Committee (OSTAC) for their review and input.

    Finally, the Development of Recommendations phase was divided into four improvement type categories: flood capacity, ecological, water quality, and passive recreation recommendations. These recommendations were divided into three phases. Phase 1 issues were deemed high priority and were planned to be addressed beginning in 2021, Phase 2 issues could be completed when staff and budget allowed, and Phase 3 issues were noted to be implemented only after reservoir dredging, if this was deemed necessary. Recommendations are summarized in the table below:


    Recommendation

    Phase

    FC1 – Update Floodplain Analysis

    Phase 1: Pursue if recommendation FC2 does not move forward.

    FC2 – Dredge to Existing Capacity

    Phase 1: flood capacity impact is uncertain, but the issue may be significant.

    FC3 – Regular Sediment and Capacity Analysis

    Phase 3: routine bathymetry and LIDAR analysis was just completed in 2020.

    E1 – Vegetating the North Shoreline

    Phase 3: would provide ecological benefit, but the riprap is currently functioning for erosion control

    E2 – Shrub Plantings

    Phase 3: action would enhance local ecosystem, but may be disrupted by dredging

    E3 – Seedling Plugs in

    Saline Areas

    Phase 3: action would enhance local ecosystem, but may be disrupted by dredging

    E4 – Turtle Basking

    Platform

    Phase 2: action would enhance local ecosystem and could be easily moved or removed to accommodate dredging

    E5 – Bee Boxes

    Phase 2: action would enhance local ecosystem and would not interfere with other activities

    E6 – Osprey Platform

    Phase 3: best implemented after dredging to avoid seasonal disturbance restrictions on nesting raptors

    E7 – Cattail Management

    Phase 1: identified by the public as a high priority issue

    WQ1 – Annual Monitoring Program

    Phase 1: provides critical baseline data and should be resumed in spring 2021

    WQ2 – Algae and Aquatic Weed Treatment

    Phase 1: issue identified by the public, annual assessments and treatments as needed should be scheduled

    WQ3 – Phosphorus

    Sampling

    Phase 2: identifying the source of the elevated phosphorus will allow targeted management, if necessary

    R1 – Educational Signage

    Phase 3: permanent placement recommended after dredging activities


    After completion of the Plaster Reservoir Management Plan, SMITH, the management plan consultant, was subsequently asked to provide a scope of work to begin to address Recommendation FC2 for Broomfield to better understand the scale of excavation being recommended (and associated costs) and to better understand some of the externalities that would be associated with the construction. This scope of work included:

    • Detailed topographic survey and recalculation of the existing flood storage capacity,

    • Alternatives analysis evaluating the possibilities for construction access,

    • Preliminary excavation plan to meet live storage capacity requirements,

    • Opinion of probable construction cost,

    • The 100-year inundation areas pre- and post-excavation,

    • Visual inspection of outlet structure and report by a structural engineer, and

    • A hydraulic analysis of existing and proposed conditions.


    Broomfield conducted an internal review of the above listed items and determined that moving forward with excavation of the reservoir at this time was not in the best interest of the community for the following reasons:

    • Without additional modeling, benefits of increased flood storage capacity are unclear,

    • Based on the current hydraulic/hydrologic model, no surrounding structures would be inundated in the current condition, so no benefit to structures immediately surrounding the reservoir would be achieved,

    • Disruption to surrounding residents for excavation activities would be significant, with an estimated 1,200 to 1,400 truck trips during construction,

    • Excavation was estimated to cost between $1.2 and $1.5 million, and

    • Ecological disruption would be significant, and would require extensive restoration, likely over several years to re-establish pre-construction conditions.


    Broomfield has requested instead that the Mile High Flood District (MHFD) add the Quail Creek and Plaster Reservoir Floodplain and Open Space Areas to their Five-year Master Drainage Plan (MDP) Studies list to develop appropriate maintenance activities and schedules as well as re-evaluate tributary area and floodplain extents. This approach allows for greater collaboration, coordination, and potential cost-sharing with communities located downstream. The strategy also brings the project into the overall MHFD master planning efforts.

    Broomfield staff has determined that with no dredging planned in the foreseeable future, all other recommendations may be evaluated for programming into Parks and Open Space & Trails maintenance activities, subject to available budgets. The City and County of Broomfield has developed a draft operations plan for Plaster Reservoir that will be presented to OSTAC on October 28, 2021 for their review and comment.

  • Open Space and Trails Advisory Committee Meeting: February 25 Presentation

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    At the Thursday, February 25, 2021 Open Space and Trails Advisory Committee (OSTAC) meeting, there will be a brief presentation of the FINAL Plaster Reservoir Open Space Management Plan (Appendix). The meeting begins at 6:00 p.m. We hope you can join us! Please see the OSTAC Agenda HERE. The FINAL Plan is the first item on the OSTAC business agenda. Information on how to join the OSTAC meeting virtually is located at the top of the agenda.

  • Open Space and Trails Advisory Committee Meeting: January 28 Presentation

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    At the Thursday, January 28, 2021 Open Space and Trails Advisory Committee (OSTAC) meeting, there will be the opportunity for both OSTAC committee members and citizens to comment on the DRAFT Plaster Reservoir Open Space Management Plan (Appendix). The meeting begins at 6:00 p.m. We hope you can join us! Please see the OSTAC Agenda HERE. The DRAFT Plan is the first item on the OSTAC Agenda business agenda. Information on how to join the OSTAC meeting virtually is located at the top of the OSTAC Agenda.

  • OSTAC Presentation: October 22

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    On October 22, OSTAC heard a PRESENTATION on the Plaster Reservoir Open Space Management Plan's preliminary findings and recommendations. Key initial recommendations include:

    • Updating the drainage report as the sedimentation analysis indicates that the reservoir's storage capacity has decreased;
    • Managing cattails;
    • Adding native vegetation along the edges of the reservoir;
    • Placing wildlife habitat features such as bird/bat boxes; and
    • Providing educational signage.


    Staff is already pursuing additional floodplain analysis, and dredging is likely in the future pending the results of the floodplain analysis. OSTAC was supportive of the research. A draft report will be presented to OSTAC on January 28, 2021.

  • Update: October 8 Open House

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    On October 8, an outdoor open house was held at Plaster Reservoir Open Space on a stunning fall evening from 4:30 to 6:30 p.m. Over 50 residents joined staff for an informal and socially distanced event to learn more about the Plaster Reservoir management plan. Staff provided information tents at the southeast corner of the reservoir. Residents were asked to complete a self-guided tour of the reservoir and then fill out a short survey. Click the self-guided tour, and please take the survey. Please be sure to submit your survey by October 31, 2020. Residents' comments about the site and technical research will be used to develop a maintenance plan that will maintain flood capacity, enhance ecosystem health, preserve trail access, maintain wildlife education experiences, and identify capital improvement projects to further these project goals. The Open Space and Trails Advisory Committee (OSTAC) will be updated on the project at its October 22 meeting. The OSTAC meeting agenda will be posted by October 17 here. This is a virtual meeting and the agenda will have the link to join the meeting.

  • Self Guided Walking Tour & Survey

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    Can't make the Open House? Take a Self Guided Walking Tour HERE.

    The City and County of Broomfield and Smith Environmental & Engineering are working together to develop a management plan for Plaster Reservoir Open Space, and we want YOU to be involved! Click HERE to take our survey before November 1st.


  • Open House October 8, 4:30-6:30pm

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    JOIN US FOR AN OPEN HOUSE AT PLASTER RESERVOIR!

    Please join us for an informal and socially distanced open house to learn more about the Plaster Reservoir management plan being developed by the City and County of Broomfield with the expertise of SMITH Environmental & Engineering.

    DATE: October 8, 2020

    TIME: 4:30 - 6:30 PM

    LOCATION: South Side of Plaster Reservoir (look for the tents)

    PARKING: If you are driving to this event, you may park in the west parking lot at Legacy High School.

    For the health and safety of the community, Broomfield staff respectfully requests that members of the community interested in attending the open house please wear a mask to help prevent the spread of Covid-19. Click HERE for Symptoms Chart & Quarantine Isolation Guidance.

Page last updated: 18 Oct 2022, 05:01 PM