Staff recommends the City Council award a contract for W.O. 25-18: Grand Avenue Trunk Main Extension and Arnold Drain Detention, to DOWL in the amount of $445,387.

W.O. 25-18: Grand Avenue Trunk Main Extension and Arnold Drain Detention, is a project that was identified during the Stormwater Utility development process that will further improve the City's stormwater infrastructure by designing and ultimately constructing a necessary capital project on Billings' West End.  This project was identified in the FY 25 CIP.  The project will mitigate existing flooding and provide additional capacity for growth west of the Arnold Drain.

This project has two major components.  The first project component is to extend the drainage infrastructure located at the intersection of Grand Avenue and Shiloh Road to the east and make a connection to the Arnold Drain. This pipe is needed for future runoff contribution to the system once Grand Avenue and local roads west of Shiloh Road are improved.  

The second project component will construct regional stormwater detention within and adjacent to the Arnold Drain to detain and meter peak runoff flows entering the undersized downstream conveyance system.  This project component solves an immediate need for greater detention within the Arnold Drain's drainage basin to alleviate current flooding that occurs in the subdivisions south of Broadwater Avenue near the Arnold Drain's intake structure located at Broadwater and 30th Street West.  The Arnold Drain intake structure was recently upgraded to help reduce debris clogging impacts; however, previously the Arnold Drain was piped east of 30th Street West and the pipe is not of sufficient size to handle current flows within the Arnold Drain and future runoff contributions that will enter the Arnold Drain from Grand Avenue west of Shiloh Road and any additional land development occurring with the Arnold Drain drainage basin.  By creating a regional detention facility, the City can better manage current flooding issues and be well positioned to accept runoff from future road and land development.  Further, adding stormwater storage upstream allows the use of existing piping downstream without costly upsizing and replacement of pipe through existing neighborhoods.           

This contract includes design and bidding services for both the pipe extension and regional storage project components.  It is anticipated that a future contract amendment for construction administration services will be presented to Council once the projects are bid for construction and construction schedules are known. 

DOWL was selected for this project using the proposal process.  Seven other proposals were received from AE2S, HDR, Horrocks, IMEG, KLJ, Morrison-Maierle, and Sanbell.  The selection was based on project team and availability; project approach; and firm qualifications and experience as related to project needs.

City Council may:

• Approve W.O. 25-18: Grand Avenue Trunk Main Extension and Arnold Drain Detention, to DOWL in the amount of $445,387; or;
• Not approve the contract. If the contract is not awarded, further development and construction of this project will be delayed and current flooding risks will remain.

Design of this stormwater capital project was budgeted in FY25 using Stormwater Funds in the amount of $1,300,000.  There are adequate funds to award this contract. Remaining funds will be used for the contract amendment for construction administration.