Authorizing a Contract Amendment 1 with WHKS, in the amount of $79,620 for final design of the Silver Lake Sediment Removal and Dam Modification - Project No. J4889.

The action before Council is a request to approve Amendment No. 1 to the engineering services contract with WHKS for the Silver Lake Sediment Removal and Dam Modification – Project No. J4889. The amendment is associated with additional engineering and design work required as the City worked through the state and federal regulatory review and permitting process. The additional work included hydraulic modeling, plan revisions and submittals, technical documentation, review meetings, and ongoing coordination with the DNR, U.S. Army Corps of Engineers (USACE), and other review agencies.

In 2024, Council reviewed the proposed 30% project design and approved an engineering services contract with WHKS to complete the final design and assist the City with advertising the project for bids following completion of the design. The original scope of services was developed based on the anticipated regulatory review process, including information provided by the DNR during pre-permit application meetings.

As the project progressed, significantly more coordination with the DNR was required than originally anticipated. The DNR permit application was submitted on July 17, 2025, and the DNR confirmed the application was complete on March 11, 2026. The City and WHKS continued technical coordination throughout the review process, including hydraulic modeling and evaluation of fish passage through the rock arch rapids, flow conditions and coordination with the adjacent wave pools, the north shore trail, and the south and east shoreline improvements. The project also required permits from the U.S. Army Corps of Engineers (USACE) and Minnesota Pollution Control Agency (MPCA). The City obtained the required MPCA permits in February 2026 and all required USACE permits by early July 2026.

The regulatory review resulted in several design refinements which were presented to Council at a July 2025 Council Study Session. The refinements included moving the rock arch rapids farther downstream and adding a stilling basin to address downstream scour and preserve additional lake area. The north shore trail location, elevation, and construction were modified to address DNR and adjacent property owner comments and improve structural stability during flooding. The design also considered restoring the east shoreline to a more historic configuration and adding open water. As the review continued, the City and WHKS refined the hydraulic model and evaluated the number and width of the rapids, rock placement, pool construction materials and methods, and flow conditions. The north shore trail and south green/recreational space were evaluated in relation to the Ordinary High Water Level, periodic flooding, and trail stability. The east shoreline improvements were also evaluated to optimize vegetation, aquatic habitat, and wildlife habitat.

These additional regulatory requirements resulted in engineering services beyond the original WHKS contract scope. DNR requests for design changes and model modifications required updates to plans and hydraulic models to be prepared and resubmitted for review. The project hydraulic model is extensive and can require most of a day to run and generate output for evaluation. WHKS also prepared additional documentation requested by the DNR and USACE, including a design memorandum for the wave pools, documentation regarding public input and the need for the trail, pedestrian and traffic accident information for the area surrounding the park, additional trail alternative analyses, two-dimensional flow renderings to evaluate flow distribution, and written responses to ongoing agency comments and requests. This additional work was necessary to address agency review comments, document the design, and advance the project through the permitting process.

The extended review and design coordination have helped address the technical requirements of the project and coordinate the flood control, recreational, aquatic habitat, and fish passage objectives. The DNR has stated that it is prepared to issue the permit and is completing the final administrative process, with permit issuance currently targeted for October 2, 2026. If the permit is not issued by that date, the DNR has indicated it will provide an updated status letter and anticipated issuance date.

WHKS has submitted Amendment No. 1 to address the additional design modeling, plan revisions and submittals, technical documentation, review meetings, and coordination with the regulatory agencies. The amendment is included in the Council packet.

Staff have reviewed Amendment No. 1 and confirm that the additional services identified in the amendment were required and completed as part of the extended regulatory review and permitting process. The amendment reflects the additional engineering work necessary to advance the project through the DNR and federal permitting requirements and complete the final project design and bid documents.  The design amendment is a 10% increase to the original final design contract of $793,385.00. 

The requested action is consistent with City procedures for amending professional services contracts when project-related work extends beyond the scope of services originally anticipated in the contract. In this case, the additional services were directly related to the Silver Lake project and were necessary to address permitting requirements, refine project components, and ensure the final project design meets the expectations established through supporting City plans and prior Council actions.

The additional work also supports project components identified in the 2012 Bicycle Master Plan, the 2015-16 Park System Plan, and the 2022-23 Silver Lake Master Plan. The north shore trail is identified in these planning documents, while the Silver Lake Master Plan also contemplated the eventual modification of the dam and identified potential future uses for areas of the park that would be affected by the modification. The additional professional services helped advance these established project objectives and obtain the necessary regulatory approvals.

Legislative Actions:

January 20, 2016: Council Meeting - Professional Services Agreement with WHKS for sediment removal- Project No. J4889 approved.

December 4, 2017: Council Meeting - Professional Services Agreement with WHKS for final design of Phase 1 sediment removal for S. Fork Zumbro River - Project No. J4889 approved.

March 19, 2018: Council Meeting - Amendment 1 to the Professional Services Agreement with WHKS for feasibility study and preliminary analysis of Silver Lake pedestrian improvements, Silver Lake Dam modifications, and sediment removal - Project No. J4889 approved.

August 19, 2019: Council Meeting - Amendment 2 to the Professional Services Agreement with WHKS for the completion of the Concept Design of Silver Lake pedestrian improvements, Silver Lake Dam modification, and sediment removal - Project No. J4889 approved.

November 2, 2019: Council Meeting - 2020 Legislative Priorities, which included Silver Lake Dam Modifications and Improvements - Project No. J7889 approved.

November 30, 2020: Study Session - Concept Design or Silver Lake pedestrian improvements, Silver Lake Dam modification, and sediment removal - Project No. J4889.

December 14, 2020: Council Meeting - Concept Design for Silver Lake pedestrian improvements, Silver Lake Dam modification, and sediment removal - Project No. J4889 approved.

January 4, 2021: Council Meeting - 2021 Legislative Priorities, which included Silver Lake Dam Modifications and Improvements - Project No. J7889 approved.

April 5, 2021: Council Meeting - Negative Declaration Decision Environmental Assessment Worksheet - Project No. J4889 approved.

October 4, 2021: Council Meeting - 2022 Legislative Priorities, which included Silver Lake Dam Modifications and Improvements - Project No. J7889 approved.

June 17, 2024: Council Meeting- Engineering Services Contract, Construction Bidding, and Negotiation of Grant Funding Agreement for the Silver Lake Sediment Removal and Dam Modification - Project No. J4889 approved.

November 18, 2024: Council Meeting - Execution of a grant agreement with the State of Minnesota, acting through it's Commissioner of Natural Resources approved.

July 28, 2025- Study Session- Update on project design.

Community Engagement:

March 27, 2019: Open House for Silver Lake Pedestrian Improvements and Silver Lake Dam Modifications.

March 27, 2019: Polco Survey placed on the City website for Silver Lake Pedestrian Improvements and Silver Lake Dam Modifications.

October 24, 2020 - November 25, 2020: Virtual Open House and Polco Survey for draft Concept Design. April 6, 2022: Public meeting held at DSIC building.

June 5, 2024: Public Informational meeting held at RCTC Heinz Center.

June 10, 2024: Public Informational meeting held virtually.

Summer of 2024: Individual discussions related to the proposed north trail layout and restoration options with the residents whose properties will be directly impacted by construction.

February 4, 2026: Presentation to Izaak Walton League.

Silver Lake Sediment Removal and Revitalization is included in the 2024-2029 Flood Control Capital Improvement Program, Map #11 (J-4889) and Map #12. Project design funding is from Flood Control Reserves.

No alternative actions are suggested at this time.