City Council is asked to award a professional engineering services agreement to HDR Engineering for all phases of the W.O. 19-21:  WRF Influent Lift Station Project to include evaluating siting options, designing, bidding and performing construction inspection and administration services for a plant influent lift station.  Project scoping and fees through the siting evaluation and preliminary design phase in the amount of $115,700 are under current consideration.  Project scoping and fees for the remaining project phases will be presented to City Council through future contract amendment proposals.

Since the 1940s, process water surface elevations through the preliminary and primary treatment facilities at the WRF cause a backwater condition at the headworks and into the upstream raw sewer interceptors. Increased flows from community growth and construction of headworks upgrades has exacerbated the backwater effect--particularly over the past 10 to 15 years. This backwater effect has significantly reduced the capacity of the 60, 48 and 36-inch raw sewer interceptors feeding the headworks and has led to the accumulation of hundreds of cubic yards settled solid material in the interceptors that is costly to remove.
 
With this siting evaluation and preliminary design of the WRF Lift Station project, HDR would:

• analyze and define the backwater condition upstream and at the WRF headworks,
• include an assessment of options for siting and constructing a lift station to relieve the backwater effect in each of the three interceptors entering the headworks,
• complete an alternatives analysis on each of the potential lift station sites which includes performance comparisons and construction and O&M cost estimates, and
• Prepare a preliminary design report recommending the most cost effective option to successfully address the reduction in capacity and backwater effects in the three interceptors and the solids deposition problem in the 60 and 48-inch interceptors.

HDR was selected for this project based on City staff review of project proposals submitted by prequalified firms. Morrison-Maierle, and DOWL/CDM Smith were the other firms considered for the project.

City Council may:

• Approve an award of the engineering contract to HDR Engineering, or;
• Disapprove an award of the contract to HDR Engineering. If this project is not completed, the problem of reduced interceptor capacity and of solids settling in the sanitary sewer interceptors upstream of the WRF will continue to get worse. Decreasing interceptor capacity along with the increase in population-driven plant flows are of particular concern. The cost to solve the problem and clean the interceptors in the future also will increase.

The W.O. 19-21:  WRF Influent Lift Station Project is in the amount of $115,700 and will use budgeted FY19 wastewater funds.

Staff recommends that Council approve a professional engineering services contract with HDR Engineering in the amount of $115,700 for W.O. 19-21, WRF Influent Lift Station.