RFP S2025-9258 St. Vrain River Pedestrian Bridge Design.pdf

REQUEST FOR PROPOSAL AND CONTRACT DOCUMENTS

FOR

St. Vrain River Pedestrian Bridge Design S2025-9258

9950 Park Avenue Firestone, Colorado 80504

September 3, 2025

TABLE OF CONTENTS

REQUEST FOR PROPOSAL INVITATION

PROJECT DESCRIPTION

AGREEMENT FOR PROFESSIONAL SERVICES

EXHIBIT A: SCOPE OF SERVICES

EXHIBIT B: FEASIBILITY STUDY

REQUEST FOR PROPOSAL INVITATION

Sealed Proposals be received by the Town of Firestone (the “Town”) at the office of the Town Clerk, 9950 Park Avenue, Firestone, Colorado 80504, until 2:00 pm local time, September 19, 2025, for the St. Vrain River Pedestrian Bridge Design (S2025-9258)

Selection and Performance Schedule: The following is the anticipated schedule of events for the RFP process September 3, 2025 Issue Request for Proposal September 12, 2025 12:00 pm (MDT) Deadline for submitting questions September 15, 2025 Response to questions posted September 19, 2025 2:00 pm (MDT) Proposal submittal deadline October 2025 Notice of Intent to Award October 2025 Board Approval of Contract

Submit Proposal To:

Town of Firestone ATTN: Town Clerk 9950 Park Avenue Firestone, CO 80504

There will be no formal bid opening for these proposals.

All proposals must be sealed with the following marked on the outside:

Proposal ENCLOSED for St. Vrain River Pedestrian Bridge Design (S2025-9258)

Proposals received after the date and time indicated and/or proposals that are not prepared and filed in accordance with the terms and conditions of the Request for Proposal will not be considered for evaluation.

A summary of the work for which the Proposal is requested consists of:

The Town of Firestone wants to construct a pedestrian bridge over the St. Vrain Creek in Firestone, CO. The selected engineer will provide planning, design, permitting, and bid-phase services necessary to deliver a complete set of construction documents suitable for competitive bidding and construction.

Project Manager Information: Questions related to this Proposal should be emailed to Kiran Bhusal, PE, at kbhusal@firestoneco.gov by 12:00 pm local time on September 12, 2025. All emailed questions will be sent with the subject line:

St. Vrain River Pedestrian Bridge Design (S2025-9258)

All answers to questions received will be sent in a formal addendum (if needed) by September 15, 2025.

NOTE: A sample Agreement for Professional Services is attached with additional General Terms and Conditions

The Town of Firestone is an Equal Opportunity Employer.

Dated this day of September 3, 2025.

TOWN OF FIRESTONE, COLORADO

PROJECT DESCRIPTION

Scope of Work: The awarded Consultant shall provide applicable services consisting of, but not limited to, the following:

The Town of Firestone intends to design and construct a new pedestrian bridge over the St. Vrain Creek to improve the non-motorized connectivity, enhance the public safety, and expand access to the Town’s trail and transportation network. The bridge will provide an important link between the neighborhood, parks, and regional trail corridors, supporting the Town’s long-term vision for mobility and recreation.

In 2024, SEH completed a feasibility study evaluating alternative crossing locations for the pedestrian bridge. The study analyzed potential sites based on constructability, environmental impacts, cost, and long-term maintenance considerations. The study’s findings and the recommended crossing location are provided in Exhibit B. The selected consultant will advance the project based on the feasibility study recommendations and through coordination with the Town.

The project is anticipated to include all tasks necessary to advance the preferred alternative through design and construction, including project management, site investigation and data collection, environmental assessment, Right-of-way evaluation, preliminary and final design, permitting and agency coordination, bid phase guidance, and construction phase services.

The Town’s goal is to deliver a safe, durable, and context-sensitive pedestrian crossing that minimizes environmental impacts, meets regulatory requirements, and provides long-term value to the community.

See Exhibit A for the Scope of Work and associated deliverables.

See Exhibit B for the Feasibility Study.

Submittal and Evaluation Criteria: Four (4) Hard copies and an electronic version of the Proposal must be submitted. Emailed proposals will not be accepted. The Town will make no reimbursement for any proposal preparation or delivery costs incurred.

In order to simplify the review process and obtain the maximum degree of comparability, the Proposal must follow the outline described below, and at a minimum, contain the required information. Respondents are encouraged to include additional relevant information. Respondents must also include a signature page with the company name, address, phone number, contact name, authorized signature, and date.

Experience

1. Understanding of the project

2. Ability to perform all aspects of the project

3. Relevant recent experience in comparable projects

4. List of clients (3) for whom similar work has been done. Include a contact name and phone number

5. Experience working with similar-sized municipalities

Qualifications

1. Key project staff and resumes

2. Ability to meet schedules within budget

3. Company resources

Fees

The Proposal shall include a fee proposal with the following information in a separate sealed envelope:

1. A not-to-exceed fee for each phase of the Scope of Work

2. Man-hour allocation and the dollar value of the time for each phase of the Scope of Work. A subtotal of man-hours and fees for each phase and category shall be provided

3. All anticipated expense items

4. An hourly rate fee schedule.

Selection Process

The Town’s selection committee will evaluate all proposals received based on qualifications and approach. Upon review, the committee may prepare a short list of companies. Sealed proposals will be evaluated for those short-listed companies, and negotiations (if necessary) will begin with the chosen Contractor.

The attached sample Professional Services Agreement will be used by the Town as the contract document for the work. By submitting a Proposal, you accept the terms of this Agreement as stated. Any deviations from this Agreement must be requested in your submitted Proposal.

AGREEMENT FOR PROFESSIONAL SERVICES

THIS AGREEMENT FOR PROFESSIONAL SERVICES (the "Agreement") is made and entered into this _____ day of ____________, 202 (the "Effective Date"), by and between the TOWN OF FIRESTONE, a Colorado municipal corporation with an address of 9950 Park Avenue, Firestone, Colorado 80504 (the "Town"), and an independent Consultant with a principal place of business at , Colorado ("Consultant ") (each a "Party" and collectively the "Parties").

WHEREAS, the Town requires professional services; and

WHEREAS, Consultant has held itself out to the Town as having the requisite expertise and experience to perform the required professional services.

NOW, THEREFORE, for the consideration hereinafter set forth, the receipt and sufficiency of which are hereby acknowledged, the Parties agree as follows:

I. SCOPE OF SERVICES

A. Consultant shall furnish all labor and materials required for the complete and prompt execution and performance of all duties, obligations, and responsibilities which are described or reasonably implied from the Scope of Services set forth in Exhibit A, attached hereto and incorporated herein by this reference and known as: St. Vrain River Pedestrian Bridge Design (S2025-9258).

B. A change in the Scope of Services shall not be effective unless authorized as an amendment to this Agreement. If Consultant proceeds without such written authorization, Consultant shall be deemed to have waived any claim for additional compensation, including a claim based on the theory of unjust enrichment, quantum merit or implied contract. Except as expressly provided herein, no agent, employee, or representative of the Town is authorized to modify any term of this Agreement, either directly or implied by a course of action.

II. TERM AND TERMINATION

A. This Agreement shall commence on the Effective Date and shall continue until Consultant completes the Scope of Services to the satisfaction of the Town or until terminated as provided herein.

B. Either Party may terminate this Agreement upon 30 days advance written notice. The Town shall pay Consultant for all work previously authorized and completed prior to the date of termination. If, however, Consultant has substantially or materially breached this Agreement, the Town shall have any remedy or right of set-off available at law and equity.

III. COMPENSATION

In consideration for the completion of the Scope of Services by the Consultant, the Town shall pay Consultant . This amount shall include all fees, costs, and expenses incurred by the Consultant, and no additional amounts shall be paid by the Town for such fees, costs, and expenses. Consultant may submit periodic invoices, which shall be paid by the Town within 30 days of receipt.

IV. PROFESSIONAL RESPONSIBILITY

A. Consultant hereby warrants that it is qualified to assume the responsibilities and render the services described herein and has all requisite corporate authority and professional licenses in good standing, required by law. The work performed by Consultant shall be in accordance with generally accepted professional practices and the level of competency presently maintained by other practicing professional firms in the same or similar type of work in the applicable community. The work and services to be performed by the Consultant hereunder shall be done in compliance with applicable laws, ordinances, rules, and regulations.

B. The Town's review, approval, or acceptance of, or payment for any services shall not be construed to operate as a waiver of any rights under this Agreement or of any cause of action arising out of the performance of this Agreement.

C. Because the Town has hired Consultant for its professional expertise, Consultant agrees not to employ Sub-Consultants to perform any work except as expressly set forth in the Scope of Services.

V. OWNERSHIP

Any materials, items, and work specified in the Scope of Services, and any and all related documentation and materials provided or developed by the Consultant shall be exclusively owned by the Town. Consultant expressly acknowledges and agrees that all work performed under the Scope of Services constitutes a "work made for hire." To the extent, if at all, that it does not constitute a "work made for hire," Consultant hereby transfers, sells, and assigns to the Town all of its rights, title, and interest in such work.

The Town may, with respect to all or any portion of such work, use, publish, display, reproduce, distribute, destroy, alter, retouch, modify, adapt, translate, or change such work without providing notice to or receiving consent from Consultant.

If the Town reuses or makes any modification to Consultant's designs, documents, or work product without the prior written authorization of the Consultant, the Town agrees, to the fullest extent permitted by law, to release the Consultant, its officers, directors, employees, and sub-consultants from all claims and causes of action arising from such uses, and shall indemnify and hold them harmless from all costs and expenses, including the cost of defense, related to claims and causes of action to the extent such costs and expenses arising from the Town's modification or reuse of the documents.

The Town expressly acknowledges and agrees that the documents and data to be provided by Consultant under the Agreement may contain certain design details, features, and concepts from the Consultant's own practice detail library, which collectively may form portions of the design for the Project, but which separately, are, and shall remain, the sole and exclusive property of Consultant. Nothing herein shall be construed as a limitation on the Consultant's right to re-use such component design details, features, and concepts on other projects, in other contexts, or for other clients.

VI. INDEPENDENT CONSULTANT

Consultant is an independent Consultant. Notwithstanding any other provision of this Agreement, all personnel assigned by Consultant to perform work under the terms of this Agreement shall be, and remain at all times, employees or agents of Consultant for all purposes. Consultant shall make no representation that it is a Town employee for any purposes.

VII. INSURANCE

A. Consultant agrees to procure and maintain, at its own cost, a policy or policies of insurance sufficient to insure against all liability, claims, demands, and other obligations assumed by Consultant pursuant to this Agreement. At a minimum, Consultant shall procure and maintain, and shall cause any Sub- Consultant to procure and maintain, the insurance coverages listed below, with forms and insurers acceptable to the Town.

1. Worker's Compensation insurance as required by law.

2. Commercial General Liability insurance with minimum combined single limits of $1,000,000 for each occurrence and $2,000,000 general aggregate. The policy shall be applicable to all premises and operations and shall include coverage for bodily injury, broad form property damage, personal injury (including coverage for contractual and employee acts), blanket contractual, products, and completed operations. The policy shall contain a severability of interests provision, and shall include the Town and the Town's officers, employees, and Consultants as additional insureds. No additional insured endorsement shall contain any exclusion for bodily injury or property damage arising from completed operations.

3. Professional liability insurance with minimum limits of $1,000,000 each claim and $2,000,000 general aggregate.

B. Such insurance shall be in addition to any other insurance requirements imposed by law.

The coverages afforded under the policies shall not be canceled, terminated, or materially changed without at least 30 days prior written notice to the Town. In the case of any claims-made policy, the necessary retroactive dates and extended reporting periods shall be procured to maintain such continuous coverage.

Any insurance carried by the Town, its officers, its employees or its Consultants shall be excess and not contributory insurance to that provided by Consultant. Consultant shall be solely responsible for any deductible losses under any policy.

C. Consultant shall provide to the Town a certificate of insurance as evidence that the required policies are in full force and effect. The certificate shall identify this Agreement.

VIII. INDEMNIFICATION

A. Consultant agrees to indemnify and hold harmless the Town and its officers, insurers, volunteers, representative, agents, employees, heirs and assigns from and against all claims, liability, damages, losses, expenses and demands, including attorney fees, on account of injury, loss, or damage, including without limitation claims arising from bodily injury, personal injury, sickness, disease, death, property loss or damage, or any other loss of any kind whatsoever, which arise out of or are in any manner connected with this Agreement if such injury, loss, or damage is caused in whole or in part by, the act, omission, error, professional error, mistake, negligence, or other fault of Consultant, any Sub-Consultant of Consultant, or any officer, employee, representative, or agent of Consultant, or which arise out of a worker's compensation claim of any employee of Consultant or of any employee of any Sub-Consultant of Consultant. Consultant's liability under this indemnification provision shall be to the fullest extent of, but shall not exceed, that amount represented by the degree or percentage of negligence or fault attributable to Consultant, any Sub-Consultant of Consultant, or any officer, employee, representative, or agent of Consultant or of any Sub-Consultant of Consultant.

B. If Consultant is providing architectural, engineering, surveying or other design services under this Agreement, the extent of Consultant's obligation to indemnify and hold harmless the Town may be determined only after Consultant's liability or fault has been determined by adjudication, alternative dispute resolution or otherwise resolved by mutual Agreement between the Parties, as provided by C.R.S. § 13-50.5- 102(8)(c).

IX. WORKER WITHOUT AUTHORIZATION

A. Certification. By entering into this Agreement, Consultant hereby certifies that, at the time of this certification, it does not knowingly employ or contract with a worker without authorization, as that term is defined in C.R.S. § 8-17.5-101(9), as amended, who will perform work under this Agreement and that Consultant will participate in either the E-Verify Program administered by the United States Department of Homeland Security and Social Security Administration or the Department Program administered by the Colorado Department of Labor and Employment to confirm the employment eligibility of all employees who are newly hired to perform work under this Agreement.

B. Prohibited Acts. Consultant shall not knowingly employ or contract with a worker without authorization, as that term is defined in C.R.S. § 8-17.5-101(9), as amended, to perform work under this Agreement, or enter into a contract with a Sub-Consultant that fails to certify to Consultant that the Sub- Consultant shall not knowingly employ or contract with a worker without authorization, as that term is defined in C.R.S. § 8-17.5-101(9), as amended, to perform work under this Agreement.

C. Verification.

1. If Consultant has employees, Consultant has confirmed the employment eligibility of all employees who are newly hired to perform work under this Agreement through participation in either the E-Verify Program or the Department Program.

2. Consultant shall not use the E-Verify Program or Department Program procedures to undertake pre-employment screening of job applicants while this Agreement is being performed.

3. If Consultant obtains actual knowledge that a Sub-Consultant performing work under this Agreement knowingly employs or contracts with a worker without authorization, as that term is defined in C.R.S. § 8-17.5-101(9), as amended, who is performing work under this Agreement, Consultant shall: notify the Sub-Consultant and the Town within 3 days that Consultant has actual knowledge that the Sub-Consultant is employing or contracting with a worker without authorization, as that term is defined in C.R.S. § 8-17.5-101(9), as amended, who is performing work under this Agreement; and terminate the subcontract with the Sub-Consultant if within 3 days of receiving the notice required pursuant to subsection 3 hereof, the Sub-Consultant does not stop employing or contracting with the worker without authorization who is performing work under this Agreement;

except that Consultant shall not terminate the subcontract if during such 3 days the Sub-Consultant provides information to establish that the Sub-Consultant has not knowingly employed or contracted with a worker without authorization, as that term is defined in C.R.S. § 8-17.5-101(9), as amended, who is performing work under this Agreement.

D. Duty to Comply with Investigations. Consultant shall comply with any reasonable request by the Colorado Department of Labor and Employment made in the course of an investigation conducted pursuant to C.R.S. § 8-17.5-102(5)(a) to ensure that Consultant is complying with the terms of this Agreement.

X. CHANGE ORDERS

A. A Change Order is a written instrument issued after execution of the Agreement signed by

Town and Contractor, stating their Agreement, as applicable, upon all of the following:

a. The scope of the change in the Work;

b. The amount of the adjustment to the Contract Price; and

c. The extent of the adjustment to the Contract Times(s).

B. All changes in the Work authorized by applicable Change Order shall be performed under the applicable conditions of the Contract Documents. Town and Contractor shall negotiate in good faith and as expeditiously as possible the appropriate adjustment such changes.

XI. MISCELLANEOUS

A. Governing Law and Venue. This Agreement shall be governed by the laws of the State of Colorado, and any legal action concerning the provisions hereof shall be brought in Weld County, Colorado.

B. No Waiver. Delays in enforcement or the waiver of any one or more defaults or breaches of this Agreement by the Town shall not constitute a waiver of any of the other terms or obligation of this Agreement.

C. Integration. This Agreement constitutes the entire Agreement between the Parties, superseding all prior oral or written communications.

D. Third Parties. There are no intended third-party beneficiaries to this Agreement.

E. Notice. Any notice under this Agreement shall be in writing, and shall be deemed sufficient when directly presented or sent pre-paid, first class United States Mail to the Party at the address set forth on the first page of this Agreement.

F. Severability. If any provision of this Agreement is found by a court of competent jurisdiction to be unlawful or unenforceable for any reason, the remaining provisions hereof shall remain in full force and effect.

G. Modification. This Agreement may only be modified upon written Agreement of the Parties.

H. Assignment. Neither this Agreement nor any of the rights or obligations of the Parties shall be assigned by either Party without the written consent of the other.

I. Governmental Immunity. The Town and its officers, attorneys and employees, are relying on, and do not waive or intend to waive by any provision of this Agreement, the monetary limitations or any other rights, immunities or protections provided by the Colorado Governmental Immunity Act, C.R.S. § 24- 10-101, et seq., as amended, or otherwise available to the Town and its officers, attorneys or employees.

J. Rights and Remedies. The rights and remedies of the Town under this Agreement are in addition to any other rights and remedies provided by law. The expiration of this Agreement shall in no way limit the Town's legal or equitable remedies, or the period in which such remedies may be asserted, for work negligently or defectively performed.

K. Subject to Annual Appropriation. Consistent with Article X, § 20 of the Colorado Constitution, any financial obligation of the Town not performed during the current fiscal year is subject to annual appropriation, shall extend only to monies currently appropriated, and shall not constitute a mandatory charge, requirement, debt or liability beyond the current fiscal year.

L. Representative Authority. Each person signing this Agreement represents and warrants that he or she is duly authorized and has the legal capacity to execute the Agreement.

IN WITNESS WHEREOF, the Parties have executed this Agreement as of the Effective Date.

TOWN OF FIRESTONE, COLORADO

Don Conyac, Mayor

ATTEST:

, Town Clerk

APPROVED AS TO FORM:

William P. Hayashi, Town Attorney

CONSULTANT

By: ________________________________

EXHIBIT A: SCOPE OF SERVICES

The Town is seeking professional engineering services for the design of a new pedestrian bridge and associated improvements over the St. Vrain Creek in Firestone, Colorado. The selected Engineer will provide planning, design, permitting, and bid-phase services necessary to deliver a complete set of construction documents suitable for competitive bidding and construction. The Engineer shall provide all necessary engineering, surveying, environmental, and related services to design the pedestrian bridge and associated improvements. The design shall address site conditions, accessibility, constructability, and long-term maintenance considerations.

Specific Services

A. Project Management

Serve as the primary point of contact with the Town.

Develop and maintain a project work plan, schedule, and budget.

Conduct regular progress meetings and prepare meeting minutes.

Provide monthly status reports summarizing progress, issues, and upcoming work.

B. Site Investigation & Data Collection

Perform topographic and boundary survey of the project area.

Collect utility information and identify potential conflicts.

Review geotechnical data; perform additional subsurface investigations if needed.

Conduct hydraulic/hydrology assessment if the bridge spans a waterway.

Document environmental conditions and constraints (wetlands, floodplains, habitat, cultural resources).

C. Environmental Assessment

Conduct an environmental review consistent with NEPA or state/local requirements.

Assess potential impacts on wetlands, water quality, wildlife habitat, threatened/endangered species, and cultural/historic resources.

Prepare environmental documentation and technical reports.

Coordinate with federal, state, and local agencies as required.

Recommend avoidance, minimization, or mitigation measures for environmental impacts.

D. Right-of-Way (ROW) Evaluation

Identify existing ROW and property ownership within the project limits.

Determine ROW needs for bridge approaches, access ramps, and construction staging.

Prepare ROW maps and legal descriptions, as necessary.

Provide technical support for easement acquisition or property negotiations (acquisitions to be performed by the Town).

Coordinate with utility providers to confirm ROW or easement needs for utility adjustments.

E. Preliminary Design

Develop alternative bridge concepts (e.g., prefabricated truss, concrete girder, suspension, or timber) suitable for site conditions and Town goals.

Prepare cost estimates and life-cycle comparisons for each alternative.

Conduct coordination with Town staff to evaluate aesthetics, accessibility, and maintenance needs.

Prepare and present a preferred alternative recommendation for approval.

F. Final Design & Construction Documents

Prepare detailed design drawings, specifications, and the engineer’s cost estimate for the approved alternative, including:

Bridge superstructure and substructure design Foundations and geotechnical recommendations Approach ramps, sidewalks, and ADA-compliant access Guardrails, handrails, fencing, and safety features Lighting, utilities, or architectural enhancements (if applicable) Erosion control and stormwater management measures

Incorporate constructability and durability considerations.

Coordinate with utility providers for relocations or protections.

Submit preliminary (60%), Final (90%), and As-Advertised (100%) design packages for

Town review.

E. Permitting & Agency Coordination

Prepare and submit permit applications as required, which may include:

U.S. Army Corps of Engineers (if spanning a regulated waterway) State Department of Transportation (if adjacent to or over a roadway) Floodplain Development Permit Environmental clearances (wetlands, wildlife, cultural, etc.)

Coordinate with applicable agencies and respond to review comments.

F. Bid Phase Services

Prepare final bid documents (plans, specifications, and cost estimate).

Assist the Town with advertising for bids and responding to bidder questions.

Prepare addenda as necessary.

Assist in bid evaluation and recommendation for award.

G. Construction Phase Services

Provide shop drawing/submittal review.

Respond to RFIs and issue design clarifications.

Perform periodic site visits to observe construction progress.

Review change orders and pay applications for conformance with design intent.

Attend final inspection and review as-built drawings.

H. Deliverables

Project work plan and schedule.

Survey-based mapping and geotechnical report.

Alternatives analysis and recommendation memorandum.

Preliminary 60%, Final 90%, and As-Advertised 100% design packages (plans, specifications, cost estimates).

Permit applications and supporting documents.

Final bid documents (sealed plans, specifications, cost estimate).

Bid-phase support documents (addenda, bid tabulation, award recommendation).

Construction support documentation and final project closeout report.

I. Additional Services

Additional services beyond those specifically outlined in this Scope of Services. Such services will be performed only upon written authorization by the Town.

Engineers | Architects | Planners | Scientists

Short Elliott Hendrickson Inc., 2000 South Colorado Boulevard, Suite 6000, Colorado Center Tower One, Denver, CO 80222-7938

720.540.6800 | 800.490.4966 | 888.908.8166 fax | sehinc.com

SEH is 100% employee-owned | Affirmative Action–Equal Opportunity Employer

FEASIBILITY STUDY REPORT

TO: Nate Haasis, PE

FROM: Parsa Kolahi, PE

DATE: February 28, 2025

RE: St. Vrain Pedestrian Bridge Feasibility Study Report

SEH No. FIREC 178250

Dear Mr. Haasis:

1. Executive Summary

The Town of Firestone (“Town”) requested Short Elliott Hendrickson, Inc. (“SEH”) to provide a feasibility study for a new pedestrian bridge crossing over the St. Vrain Creek in Firestone, Colorado. The report assesses three alternative crossing locations, considering factors such as existing site conditions, trail systems, proposed bridge design, hydrology and hydraulics, environmental and utility impacts, and construction costs. The engineer’s recommendation is presented in Section 8 of this report.

Figure 1 Project Vicinity Map

KBhusal Text Box

EXHIBIT B

St Vrain Pedestrian Bridge Feasibility Study Report February 28, 2025

Engineers | Architects | Planners | Scientists

Short Elliott Hendrickson Inc., 2000 South Colorado Boulevard, Suite 6000, Colorado Center Tower One, Denver, CO 80222-7938

720.540.6800 | 800.490.4966 | 888.908.8166 fax | sehinc.com

SEH is 100% employee-owned | Affirmative Action–Equal Opportunity Employer

2. Existing Site Conditions

On May 7, 2024, the project team and Town staff visited the project site. The site visit attendees included the following:

Julie Pasillas Town of Firestone Director of Water and Community Resources

Nate Haasis, PE Town of Firestone Town Engineer

Chuck Bradt Town of Firestone Parks Division Manager

Parsa Kolahi, PE SEH Bridge Engineer, Project Manager

Wayne Howard, PE SEH Client Service Manager

Darcy Tiglas Tiglas Ecological Services Biologist

During this visit, data and pictures were collected to support the feasibility study. The following information is based on the site visit as well as a desktop investigation.

A drop structure is located adjacent to the I-25 frontage road bridge. This structure is constructed of grouted riprap and extends the entire width of the creek.

A large area on the north riverbank is protected by rock riprap with a width ranging from 20 ft to 100 ft, narrowing towards the east.

Figure 2 Existing drop structure located adjacent to the frontage road bridge - Looking SE

Engineers | Architects | Planners | Scientists

Short Elliott Hendrickson Inc., 2000 South Colorado Boulevard, Suite 6000, Colorado Center Tower One, Denver, CO 80222-7938

720.540.6800 | 800.490.4966 | 888.908.8166 fax | sehinc.com

SEH is 100% employee-owned | Affirmative Action–Equal Opportunity Employer

In September 2013, Longmont experienced a significant flood event. The flooding along the St. Vrain Creek displaced many residents and affected personal property, businesses, and public spaces. It caused extensive damage to the city's infrastructure and the St. Vrain Greenway trail system. The riprap is believed to have been installed following the 2013 flood event to provide erosion and scour protection. Small sections of the riprap at the base of the riverbank appear to have been displaced. However, the remaining sections that were visible above the water surface appear to be in good condition and remain stable.

Figure 3 Aerial project map showing the approximate aera of existing riprap and drop structure

Figure 4 Condition of the existing rock riprap along the north creek bank

Engineers | Architects | Planners | Scientists

Short Elliott Hendrickson Inc., 2000 South Colorado Boulevard, Suite 6000, Colorado Center Tower One, Denver, CO 80222-7938

720.540.6800 | 800.490.4966 | 888.908.8166 fax | sehinc.com

SEH is 100% employee-owned | Affirmative Action–Equal Opportunity Employer

The north bank of the creek has a consistent horizontal and vertical profile. It is primarily stabilized by riprap, enhancing its stability. In contrast, the south bank exhibits more variability in its horizontal and vertical profiles and has a denser vegetation cover compared to the north bank. This makes the south bank's terrain potentially more challenging for construction activities and requiring more earthwork.

2.1. Trail Systems

There are two trail systems within the project area: a gravel trail system on the north side and The Weld

Legacy Trail, a concrete trail system on the south side of the creek. The gravel trail on the north side connects to a concrete trail on the north side of Peninsula Park. The Weld Lagacy Trail crosses under I-25 bridges and connects to the St. Vrain State Park Trails, west of the highway.

There is a pedestrian bridge on the Weld Legacy Trail about 1500 ft east of the frontage road bridge. The structure is a weathering steel truss bridge with concrete deck and timber handrails, designed and fabricated by CONTECH in February 2021 (as seen on the plaque on the bridge).

3. Proposed Bridge

The proposed bridge configuration aims to connect sections of the multi-use trail, accommodating pedestrian and bicycle traffic, so that the frontage road does not have to be used to cross the river. The clear width of bridge is assumed to be 10 ft, providing accessibility for maintenance vehicles.

The final design of all bridge components should follow the bridge loading recommendations outlined in

CDOT Design Manuals and AASHTO LRFD Guide Specification for the Design of Pedestrian Bridges.

Construction the bridge with adequate freeboard over the design flood elevation is required, especially given the area's history of significant flooding events.

3.1. Structure Type

Through communication with the Town, the prefabricated steel truss bridge has been selected due to its numerous advantages. Economically, it is a favorable option as it allows for off-site fabrication and quick on-site assembly, significantly shortening the construction period compared to conventional girder or slab bridges. The use of weathering steel ensures that the bridge will blend harmoniously with the natural environment. Furthermore, the proposed bridge design will match the existing pedestrian bridge on the

Weld Legacy Trail, maintaining regional continuity and aesthetic coherence.

3.2. Bridge Location Alternatives

SEH proposed several options for the location of the crossing. Through communication with the Town, three location alternatives were selected for this study. The alternatives are numbered from west (adjacent to the

Figure 5 Existing pedestrian bridge on the Weld Legacy Trail

Engineers | Architects | Planners | Scientists

Short Elliott Hendrickson Inc., 2000 South Colorado Boulevard, Suite 6000, Colorado Center Tower One, Denver, CO 80222-7938

720.540.6800 | 800.490.4966 | 888.908.8166 fax | sehinc.com

SEH is 100% employee-owned | Affirmative Action–Equal Opportunity Employer frontage road bridge) to east. Below are descriptions for each alternative. An option of widening the existing frontage road bridge to accommodate pedestrian/cyclist use was considered, but not moved forward as a viable option due to the complexity and durability concerns for modifying an existing bridge.

The three proposed alternatives provide different benefits and challenges in terms of construction complexity, environmental impact, and user experience. An overview of all three alternatives, along with individual plan and profile drawings, are included in the attachments.

➢ Alternative 1

This location is the closest to the Interstate Highway 25. As mentioned earlier in this report, a drop structure is located just to the east of the frontage road bridge introducing several complications for the proposed pedestrian bridge. The drop structure could create turbulent flow conditions, increasing the risk of erosion and potential damage to the bridge supports. Additionally, it would likely necessitate more complex and costly engineering solutions to ensure the stability and longevity of the pedestrian bridge. The proximity to the existing I-25 frontage road bridge can limit the space for construction activities. The proximity to the highway also brings significant noise from vehicles decreasing the user experience and making this option less desirable for a pedestrian bridge crossing.

➢ Alternative 2

Alternative 2 is located further to the east and towards the downstream area from the Interstate Highway

25 bridges and the drop structure. This location takes advantage of the natural characteristics of the site, where the stream is less turbulent. As the project site is situated within a high-risk flood zone, generally, positioning the bridge further downstream reduces the complexities associated with turbulent flow conditions and potential erosion risks. Consequently, this alternative presents a more favorable option compared to Alternative 1.

➢ Alternative 3

This alternative is the furthest from the highway, making it more desirable for a pedestrian crossing in terms of noise reduction. An additional advantage is the presence of an existing trail on the north side that connects the bridge directly to a subdivision north of the lakes. The bridge crossing at this location is slightly shorter than the other two alternatives, yet it requires more earthwork and a longer concrete trail connection to the Weld Legacy Trail on the south. Hydraulically, this is the most favorable option, offering the largest freeboard and the least potential for scour.

In terms of environmental impact, a preliminary evaluation suggests that this location offers the least environmental impact out of all alternatives.

4. Bridge Hydrology and Hydraulics

4.1. Flood Hazard

The project site is located in a FEMA flood Zone AE area defined as Special Flood Hazard zone with known base flood elevation (BFE). The site does have a regulated floodway. The project area is included in map panel 08123C1890F effective September 26, 2024. A Firm Map of the area is included in the attachments.

4.2. Hydrology

St. Vrain River at the location of the project is a natural channel with relatively defined stream alignment with minimal braiding or meander. The stream bed is rocky with sand and silt deposits. The riverbanks adjacent to the proposed design alternatives are vegetated with shrubs and grass with adjacent commercial development beyond that.

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➢ Flow Data

Flow data for the project was obtained from the existing model provided by Weld County completed by

AECOM in 2017. The 100-year flow was selected as the design flow for the study per Weld County

Engineering and Construction Criteria (WCECC) manual and CDOT BDM.

The HEC-RAS model boundary conditions obtained from the existing model for St. Vrain can be found in the table below.

Location 100-Year Peak Flow (cfs) 100-Year Downstream WSE (XS 1005)

St. Vrain Ped Bridge 24,171 4823.78 ft

The existing model provided by the county operates as an unsteady flow model with lateral structures parallel to the project area causing maximum flows to vary across cross sections. The proposed modeling for the pedestrian bridge alternatives accounts for the varying flows by implementing flow changes at cross sections to reflect conditions in the existing model. The total flow at each cross section can be found in the tables below.

4.3. Hydraulic Modeling

➢ Criteria

The Weld County Engineering and Construction Criteria (WCECC) manual and CDOT Bridge Design

Manual (BDM) were consulted as the major sources of design criteria. The pedestrian bridge alternatives are located in FEMA Zone AE. For CDOT criteria for scour analysis and countermeasure design, the 100-year and 500-year events were evaluated to determine necessary scour protection.

➢ Assumptions

Assumptions for modeling the proposed alternatives included using the 100-year flow values and WSE information for St. Vrain River from the existing model provided by the client.

➢ Methodology

The study was conducted using HEC-RAS 6.3.1. The software was used to analyze the existing conditions and analyze proposed alternatives to select the best option for the proposed bridge.

Cross-Section 100-Year Peak Flow (cfs)

XS 5890 24171

XS 5499 24170

XS 4963 24169

XS 4437 16821

XS 3851 15137

XS 3274 16101

Cross-Section 100-Year Peak Flow (cfs)

XS 2807 15148

XS 2341 11105

XS 1846 9585

XS 1408 9570

XS 1005 10830

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The existing model provided by the client was updated using LiDAR to model the existing channel and subsequent pedestrian bridge alternatives. The field survey encompassed the channel and surrounding terrain for approximately 2,000 feet upstream and 2,000 feet downstream of the crossing. Manning’s n values were chosen using tables 8.1 and 8.2 of the CDOT BDM.

Several bridge span alternatives were analyzed to determine the most economical design. Additional cross sections were also added to the proposed modeling to more accurately portray the proposed bridge alternatives.

The proposed bridge alternatives were modeled to determine freeboard during the 100-year flooding event.

The existing channel bottom profile would be maintained along the effected reach. The HEC-RAS summary table can also be found in the attachments.

➢ Results

Water surface elevations for each bridge span alternative were compared to determine the impacts of various span opening widths on the water surface profile of the river and flow velocities. The lower chord of the proposed structures is positioned at the maximum feasible elevation without resulting in excessively steep or extended trail ramps leading to the bridge.

Alternative 3 (furthest downstream along the river) provides the most freeboard compared to the other alternatives. A summary of the hydraulic data results can be found in the table below.

Alternative

Option

Downstream

Velocity

(ft/s)

Upstream

Velocity

(ft/s)

US Water

Surface

Elevation

Low

Chord

Elevation

Freeboard

(ft)

Alternative 1 7.75 6.52 4836.06 4832.50 -3.58

Alternative 2 15.11 10.72 4834.16 4832.50 -1.66

Alternative 3 10.01 7.75 4829.04 4832.50 3.46

➢ Scour Protection

The 100-year and 500-year scenarios were evaluated to determine the highest velocity on the proposed bridge alternatives and were selected to be used for countermeasures design of the existing bridge. HEC-

23 (FHWA-NHI-09-112, 2009) Design Guideline 14 at 100-year scenario was used to determine 15” D50 riprap with 30” thickness would be required at the maximum width of 16’ from the toe of the abutment for

Alternatives 1. Alternative 2 at the 500-year scenario was used to determine 24” D50 riprap at 48” thickness with same abutment parameters as Alternative 1. Alternative 3 at the 500-year scenario was used to determine 18” D50 riprap at 36” thickness with same abutment parameters as Alternative 1. The estimated volume of riprap recommended to protect the proposed alternatives are as follows in the table below. Scour countermeasure calculations can be found in the attachments.

Alternative Option D50 Volume (cubic yards)

Alternative 1 15” 63

Alternative 2 24” 90

Alternative 3 18” 65

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5. Bridge Alternative Decision Matrix

Several key factors, as explained in Sections 5.1 through 5.8 below, are evaluated for each alternative and summarized in a Bridge Alternative Decision Matrix presented in the attachments. This matrix compares the bridge alternatives proposed in this report and utilizes a ranking system to inform the decision-making process. A weight is assigned to each factor based on its importance and an overall weighted score is calculated for bridge alternative comparison.

5.1. Construction Costs

Construction costs include all expenses associated with construction, including mobilization, materials, labor, engineering services during construction, temporary trail traffic control, erosion control, utility relocations, and right-of-way and easement services.

➢ Erosion Control Costs

Erosion control costs associated with bridge construction over a waterway vary depending on the project scope. The primary factors influencing cost include the earthwork along the riverbanks, the length of disturbed banks, and chosen control measures. Sediment fences, silt curtains, and anchored geotextiles are common best practices. In some cases, more specialized techniques like bioengineering with native vegetation or rock riprap may be necessary, further influencing the overall erosion control budget. Additional considerations may be necessary for work in channel including temporary cofferdams to isolate the construction area from the creek flow. These factors necessitate a detailed project design and cost estimation to determine the most appropriate and cost-effective erosion control strategy.

➢ Mobilization Costs

Mobilization costs encompass the preliminary expenses incurred by the contractor to prepare for bridge construction. This includes the transportation and setup of necessary equipment, materials, and temporary facilities at the site. Additionally, mobilization costs account for the initial deployment of labor for site preparation, permitting, and logistical planning. These non-construction activities are essential for initiating the project but are separate from the bridge construction itself.

For cost assessment purposes in this report, erosion control and mobilization costs are assumed as percentages of the total construction cost. Refer to Cost Comparison table in the attachments for additional information.

5.2. ROW Impacts

Right of Way (ROW) impacts refer to the effects of bridge construction on the land required for the project.

This includes acquiring easements and property, which may result in additional costs and potentially displacing existing land uses. The analysis of ROW impacts assesses the extent of land acquisition needed, the impact on adjacent properties, and the estimated associated costs for obtaining the necessary rights of way. Ensuring minimal disruption to property owners and maintaining compliance with regulatory requirements are key objectives in this evaluation.

5.3. Hydraulic Impacts

Potential hydraulic impacts and recommended mitigation measures are discussed in more detail in section

4 of this report.

5.4. Environmental Impacts

An environmental assessment report prepared by Tiglas Ecological Services (“Tiglas”) evaluated the three potential crossing locations, with the easternmost location having the least environmental impact.

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Key environmental permitting considerations include the need for a Wetland Delineation and Wetland

Finding Report, a 404-Wetland Permit, and Pre-Construction Notification. Evaluations for sensitive species and potential impacts on small fish under Senate Bill 40 are likely required, along with an Initial Site

Assessment for hazardous materials, a noxious plant survey, and measures to protect birds-of-prey and migratory birds. No significant historic or cultural resources were found, and an environmental justice memorandum should assess impacts on disadvantaged populations. Mitigation measures, such as on-site mitigation or purchasing wetland banking credits, should be implemented if impact thresholds are exceeded.

Refer to the attachments for the complete report and further details.

5.5. Utility Impacts

SEH researched several utility records depicting the existing utilities in the vicinity of the proposed crossing locations. Through a desktop review of the records and field observations, the following utilities were identified within or near the anticipated construction footprint:

➢ Oil and Gas

• Black Hills Energy-Weld County

• Magellan Midstream Partners LP

• Occidental/Kerr McGee Prod

• Midstream/Kerr McGee-Gas

• Midstream/Kerr McGee--Oil

➢ Electric

• Occidental/Kerr McGee-Elec

• Town of Firestone

• United Power, Inc.

• Zayo Bandwidth

➢ Fiber

• CDOT Fiber Optic Backbone

• Occidental/Kerr McGee-Fib

• Town of Firestone

• Zayo Bandwidth

➢ Water

• Central Colorado H20 Conservation

• Central Weld County Water District

• Little Thompson Water

• Town of Firestone

➢ Other

• Sewer - Central Colorado H20 Conservation; St Vrain Sanitation District; Town of Firestone

• Irrigation - Town of Firestone

The approximate locations of the above utilities are shown in the Bridge Location Alternatives exhibit in the attachments.

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5.6. Constructability

Constructability refers to the ease and efficiency with which a construction project can be built.

Constructability involves considering factors such as site conditions and constraints, material availability, construction methods, and potential obstacles to streamline the construction process and minimize delays, costs, and risks.

5.7. Trail Traffic Control

Trail Traffic Control during construction is crucial to ensure the safety and…