City Council is asked to approve Amendment No. 1 to the City's professional engineering services contract with HDR Engineering (HDR) for W.O. 19-21, WRF Influent Lift Station in the amount of $649,400.  HDR was selected to evaluate, design, bid and perform construction inspection and administration services for this project in April 2019.  The initial contract for $115,700 was approved by Council through the siting evaluation and preliminary design phase only.  HDR has completed this evaluation and preliminary design and staff is ready to move forward on the remaining project design, bidding and construction phases.

During the siting evaluation and preliminary project design, HDR and City staff studied the backwater condition upstream and at the WRF Headworks and determined that the best location for the new lift station is on the south side of the new Siphon Headbox located just south of Alkali Creek.  Other findings and recommendations reached at the conclusion of preliminary design and contained in the Scope of Work for completion under Amendment No. 1 include:

• sizing pumps initially for 40 MGD incoming flow, expandable to 80 MGD,
• allowing gravity flow into the WRF Headworks when the lift station is not operating,
• allowing the lift station to be intermittently or continuously operated,
• design to allow future interceptors to enter the lift station at lower elevations with improved pipe slopes,
• include a building with heat and ventilation over the pump motors and electrical gear as a bid alternate, and
• include a pump in the Headworks Inlet Box to flush the Heights Interceptor and In-Plant Sewer as a bid alternate.

City Council may:

• Approve Contract Amendment No. 1 with HDR Engineering, or;
• Disapprove Contract Amendment No. 1 with 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 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 original professional services contract amount is $115,700.  Proposed Amendment No. 1 in the amount of $649,400 would increase the total contract amount to $765,100.  There are adequate wastewater funds budgeted in FY20 for this project.

Staff recommends that Council approve Amendment No. 1 to the City's professional engineering services contract with HDR Engineering for W.O. 19-21 in the amount of $649,400.