TO: Mayor and Members of City Council
THRU: Kelly Strickland, Assistant City Manager
FROM: Sheila Thomas-Ambat, Public Services Director
DATE: January 26, 2026
RE:Title
Approval of Professional Service Contract Execution Recommendation for $1,827,735 for the design of the Arran Lake West Dam Overtopping Protection Project Title
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COUNCIL DISTRICT(S):
Council District(s)
6
b
Relationship To Strategic Plan:
Goal 1: Safe and Secure Community
Goal 3: High Quality Built Environment
Goal 4: Desirable Place to Live, Work and Recreate
Executive Summary:
Council is asked to authorize the execution of an engineering services contract in the amount of $1,827,735 for the design of the Arran Lakes West Dam (ALWD) Overtopping Protection Project.
This qualification-based selection of Hazen and Sawyer will utilize the City’s On-Call Professional Engineering Services for Stormwater Systems Design and Construction Administration.
Background:
In December 2021, Council directed staff to begin the design of two projects identified in the Beaver Creek 3 Watershed Study: the Rhemish Drive Drainage Improvements and the Rockford Drive Drainage Improvements.
Both projects are currently under design. As part of the design process, staff use hydraulic modeling to predict changes in stormwater surface elevations downstream of the project sites under various storm conditions. Staff evaluates downstream impacts to the extent the models indicate any measurable increase in water surface elevations attributable to the proposed infrastructure.
Results from this analysis may require modifications to the proposed project designs, including potential property acquisition or condemnation. One such trigger occurs when modeling shows a reduction in downstream “level of service,” meaning increased stormwater volume or velocity negatively impacts the performance of existing downstream stormwater infrastructure.
Both the Rockford Drive and Rhemish Drive projects discharge into Beaver Creek Tributary B (BCTB). Downstream of BCTB is the Arran Lakes West Dam (CUMBE-067), a privately owned, “high hazard” dam with a City-maintained roadway overtopping the dam.
While modeling indicates that the proposed drainage improvements do not reduce the existing level of service of the dam, the depth and frequency of roadway overtopping may change slightly. As a result, staff conducted both an impact evaluation and a detention evaluation, considering localized and regional detention alternatives.
The comparative analysis of localized versus regional detention concluded that overtopping protection of the Arran Lakes West Dam represents the most direct, effective, and economical solution to address potential flow changes. Overtopping protection directly safeguards the facility and is largely independent of future changes to secondary drainage systems.
At the August 5, 2024 Council Work Session, Council directed staff to proceed with project development and design of the Arran Lakes West Dam Overtopping Protection Project.
Issues/Analysis:
In October 2024, Hazen began providing preliminary engineering services in support of Council’s direction to advance project development. The Preliminary Engineering Report was completed in late 2025.
The scope of this services contract is to provide detailed design for the Arran Lakes West Dam rehabilitation work.
Budget Impact:
There is no impact to the General Fund. Budget for the design services of this project was included in Council’s adopted FY26 budget utilizing Stormwater Enterprise Funds.
Options:
1. Authorize execution of an engineering service contract for professional services in the amount of $1,827,735 for the design of the Arran Lakes West Dam (ALWD) Overtopping Protection Project to the consulting firm Hazen & Sawyer.
2. Do not authorize the execution of an engineering service contract for professional services in the amount of $1,827,735 for the design of the Arran Lakes West Dam (ALWD) Overtopping Protection Project to the consulting firm Hazen & Sawyer and provide further direction to staff.
Recommended Action::Recommended Action
Authorize the execution of an engineering service contract for professional services in the amount of $1,827,735 for the design of the Arran Lakes West Dam (ALWD) Overtopping Protection Project to the consulting firm Hazen & Sawyer.
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Attachments:
ALWD Rehab WA